Lubrication and Anti-Rust Properties of Jeffamine-Triazole Derivative As Water-Based Lubricant Additive

Article Lubrication and Anti-Rust Properties of Jeffamine-Triazole Derivative as Water-Based Lubricant Additive

Jiabei Wang 1,2, Wenjing Hu 1,* and Jiusheng Li 1,*

1 Laboratory for Advanced Lubricating Materials, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China; [email protected] 2 University of Chinese Academy of Sciences, Beijing 100049, China * Correspondence: [email protected] (W.H.); [email protected] (J.L.)

Abstract: With the worldwide concern of environmental protection, water-based lubricants exhibit extensive potential applications due to their advantages of energy-conservation, innocuity, and competitive price. Nonetheless, the common lubricating additives currently available in the market are mainly oil-based, while multifunctional water lubricants are rare. This paper reports a sulfur- and phosphorus-free multifunctional additive with high water-solubility, which is applicable for multitype material surfaces. Speciﬁcally, through the Mannich reaction method, a Jeffamine-triazole derivative was synthesized from olyetheramine and benzotriazole. Compared with distilled water, the derivative exhibited superior friction reduction and wear resistance properties in water, with the friction reduction rate up to 72.7% and 70.2% for steel/steel and steel/aluminum contacts, respectively, when the concentration of the JD2000 is 2 wt.%. Remarkably, the wear resistance property for steel/aluminum contact is improved by 88.2%. Moreover, the additive showed corrosion inhibition on the metal surface by 75.5%. We further revealed the lubrication and anti-rust mechanisms: the

additives are adsorbed on the surfaces through nitrogen atoms, and the long-chain structure of polyether can cover the sliding surfaces, forming a stable viscoelastic ﬁlm to prevent the severe

Citation: Wang, J.; Hu, W.; Li, J. damages caused by the direct contact between rough friction pairs. Concurrently, the dense pro- Lubrication and Anti-Rust Properties tective ﬁlm can resist the corrosion of environmental media on the metal surface and delay the of Jeffamine-Triazole Derivative as metal rust. This research may provide a candidate for an ecofriendly multifunctional water-based Water-Based Lubricant Additive. lubricating additive. Coatings 2021, 11, 679. https:// doi.org/10.3390/coatings11060679 Keywords: water lubrication; multifunctional ecofriendly additive; tribological property; corrosion inhibition performance Academic Editor: Rubén González

Received: 7 May 2021 Accepted: 2 June 2021 1. Introduction Published: 4 June 2021 With the severe situation of environmental problems and the worldwide shortage

Publisher’s Note: MDPI stays neutral of oil resources [1], traditional lubricants and greases are facing serious challenges. It is with regard to jurisdictional claims in imperative to develop new strategies of realizing multifunctional “green” lubrications. As published maps and institutional afﬁl- a novel type of ecofriendly lubrication method, water lubrication exhibits a wide appli- iations. cation prospect in drilling equipment, tail bearing, metal tool processing, etc. due to its advantages of low cost, high thermal conductivity, high ﬂuidity, and environment friendli- ness [2]. However, the development of water-based lubrications is limited by the problems of low viscosity, poor lubrication performance, and serious corrosion [3]. Additionally, most lubricating additives are applicable for oil or greases, while water-based additives Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. are relatively few [4]. Commonly used water-based additives have some unavoidable This article is an open access article shortcomings. Borate, for example, has poor solubility in water and cannot play a good role distributed under the terms and in lubrication. Sulfur and phosphorus additives contain active elements, which can easily conditions of the Creative Commons cause environmental pollution, such as water eutrophication. Relevant environmental laws Attribution (CC BY) license (https:// and regulations have clearly banned the use of phosphorus compounds [5]. In addition, the creativecommons.org/licenses/by/ preparation of nano-water-soluble additives is generally complicated and costly. Therefore, 4.0/). it is very important to promote the development of water-based lubricants to obtain green

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multifunctional lubricating additives with good lubricity and anti-rust properties through a simple preparation method [6]. Water-soluble polymer additives, especially the polymers with polar groups, have gradually attracted the attention of researchers [7]. According to the principle of coordination chemistry, the polar group containing a lone pair of electrons can be combined with the empty d orbital of the metal ions through coordination bonds, forming a stable complex, thereby realizing the firm adsorption of the polymer on the rough metal surface and deposition to form multiple closely arranged molecular layers to prevent direct contact with rough surfaces [8–11]. When the friction pairs are sheared mutually, the loosely bonded outer molecules between the layers are easily cut off, realizing an effective lubrication [12]. Meanwhile, the stable adsorption of the protective film can promote the abilities of anti-rust and anti-corrosion as well. Desanker et al. [13] prepared a series of nitrogen heterocyclic friction modifiers, which can enhance surface adsorption through chelation. Relevant studies have confirmed that nitrogen-containing polar groups have outstanding performance in the adsorption of polymers and metal surfaces. Under mild rolling or sliding conditions, lubricant additives’ molecules in a formu- lated lubricant help mitigate friction and wear in the boundary lubrication regime [14]. Benzotriazole is a kind of commonly used industrial corrosion inhibitor, which can react on various metal surfaces to form an insoluble anti-rust layer and achieve corrosion inhibition effect [15]. Jeffamine with high molecular weight is commonly used as a gasoline detergent, which has excellent detergency, dispersion, demulsification, corrosion inhibition, and anti-oxidation properties. It can also remove the original CCD (deposits formed in the combustion chamber of the engine) without generating sediment itself [16]. These two common industrial machinery materials are insoluble in water at room temperature and cannot be used in the water lubrication field. Based on the above background, we used water-insoluble Jeffamine (2000) and benzotriazole as raw materials to synthesize a sulfur- and phosphorus-free water-soluble Jeffamine-triazole derivative (JD2000) through the Mannich reaction. The structure and molecular weight distribution of the additive were characterized by MALDI-TOF mass spectrometer, Fourier transform infrared spectrometer, nuclear magnetic resonance equipment, and gel permeation chromatograph. The adsorptive and anti-rust properties of the JD2000 onto metal surfaces were evaluated by water contact angle tests and iron scraps tests. Furthermore, the tribological properties of the water-based additive on different metal surfaces were investigated. To verify the adsorption of the JD2000 on metal surface, quartz crystal microbalance with dispersion was used to study the adsorption behavior. The composition and chemical state of the worn surface are important in explaining the relationship between the molecular structures and tribological properties of the additive. Therefore, X-ray photoelectron spectroscopy, white light interference method, scanning electron microscope, energy dispersive spectrometer, and MALDI-TOF mass spectrometer were used to analyze the worn traces. Based on the results of tribological experiments, adsorption behavior test, and surface analysis, we clarified that the adsorption performance of the additive on the metal surface promotes the tribological performance and the anti-rust property.

2. Materials and Methods 2.1. Materials The analytical reagents, Jeffamine D2000 and benzotriazole, were purchased from the Shanghai Titan Scientiﬁc Co., Ltd., Shanghai, China. The formaldehyde, sodium hydroxide, and sulfuric acid were purchased from the Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. To ensure easy commercialization, all of the raw materials can be obtained from the commercial market without further puriﬁcation.

2.2. Preparation of the JD2000 The JD2000 derivative were prepared via the following procedures. First, the benzotriazole (1.25 g, 10 mmol) was introduced into the sodium hydroxide solution (8 wt.%, Coatings 2021, 11, x FOR PEER REVIEW 3 of 20

2.2. Preparation of the JD2000 The JD2000 derivative were prepared via the following procedures. First, the ben- Coatings 2021, 11, 679 3 of 19 zotriazole (1.25 g, 10 mmol) was introduced into the sodium hydroxide solution (8 wt.%, 100 mL). Then, a Jeffamine D2000 (21.05 g, 10 mmol) and 37 wt.% formaldehyde solution

(0.85 g, 10 mmol) were100 mL).added Then, under a Jeffamine magnetic D2000 stirring. (21.05 g, 10 The mmol) mixture and 37 wt.%was formaldehydeheated to 90 solution °C, and the sulfuric acid(0.85 aqueous g, 10 mmol) solution were added(80 wt under.%, 8 magnetic mL) was stirring. introduced The mixture into was the heated mixture. to 90 ◦ C, The reaction continuesand thefor sulfuric10 h at acid 90 aqueous°C. Finally, solution the (80 mixture wt.%, 8 mL) was was cooled introduced to a into yellowish the mixture. ◦ diaphanous viscousThe liquid, reaction and continues the Jeffamine-triazole for 10 h at 90 C. Finally, derivatives the mixture was(JD2000) cooled towere a yellowish ob- diaphanous viscous liquid, and the Jeffamine-triazole derivatives (JD2000) were obtained. tained. The reaction Theformula reaction and formula structural and structural formula formula of the of the JD2000 JD2000 are are shownshown in in Figure Figure1. 1.

Figure 1. (a) The reactionFigure 1. (formula.a) The reaction (b) The formula. structural (b) The structural formula formula of the ofproduct. the product.

2.3. Pretreatment of the Friction Pair 2.3. Pretreatment of the Friction Pair In practical use, different friction pairs often appear in different working conditions. In practical use,Due different to its high friction tensile pairs strength often and appear low cost, in steel different is used inworking buildings, conditions. infrastructure, Due to its high tensiletools, strength ships, trains, and cars, low machines, cost, steel electrical is appliances,used in buildings, and weapons. infrastructure, With the properties of low density, non-toxicity, easy recovery, electrical conductivity, and heat transfer, the tools, ships, trains, cars,recycling machines, of aluminum electric alloysal hasappliances, been shown and to provide weapons. major With economic the benefitsproper- and ties of low density, non-toxicihas been widelyty, easy used recovery, in aerospace, electrical automation, conductivity, and advanced and machinery. heat transfer, To meet the the recycling of aluminumneeds of different alloys conditionshas been and shown expand to the provide usage of the major products, economic 304 stainless benefits steel and and has been widely6061 used aluminum in aerospace, alloy substrates automation, were selected and as advanced the lower stationary machinery. block inTo the meet friction pairs. Before the friction test, steel and aluminum plates were immersed in a mixture of the needs of differentpetroleum conditions ether and (analytical expand pure, the Sinopharm usage of Chemical the products, Reagent Co., 304 Ltd., stainless Shanghai, steel China) and 6061 aluminumand alloy ethanol substrates (analytical were pure, purityselected 99%, Sinopharmas the lower Chemical stationary Reagent Co.,block Ltd., in Shanghai, the friction pairs. BeforeChina). the friction Afterwards, test, ultrasonication steel and wasaluminum performed plates in a water were bath immersed for 15 min to in remove a the surface impurities and contaminants. The surface was then blow-dried using nitrogen mixture of petroleumgas flow.ether The (analytical resulting steel pure, and aluminum Sinopharm plates Chemical were retained Reagent for tribological Co., testing.Ltd., Shanghai, China) and ethanol (analytical pure, purity 99%, Sinopharm Chemical Reagent Co., Ltd., Shanghai, 2.4.China). Friction Afterwards, and Wear Tests ultrasonication was performed in a water bath for 15 min to remove theA Bruker surface UMT-tribolab impuriti testeres and (Bruker, contaminants. Billerica, MA, USA)The wassurface used towas evaluate then the tribological performance of the additive. The tests were performed in a ball-on-block blow-dried using nitrogenconfiguration. gas Contactflow. The between resu thelting friction steel pairs and was achievedaluminum by applying plates pressurewere re- to the tained for tribologicalupper testing. running ball (8 mm in diameter, GCr15 steel, hardness of approximately 59–61 HRC) against the lower stationary block in the reciprocating mode. The variation in friction force 2.4. Friction and Wearand Tests displacement with time during the test were controlled using a computer, and the entire process was recorded. The test was under a load of 7 N at a frequency of 4 Hz at A Bruker UMT-tribolabroom temperature tester (Bruker, (25 ◦C) and Bill ambienterica, humidity MA, USA) (30.2%) was for used 30 min. to Distilled evaluate water the and tribological performancesolutions of with the different additive. concentrations The tests of thewere JD2000 performed were adopted in asa theball-on-block lubricants. All of configuration. Contactthe testsbetween were repeated the friction three times. pairs was achieved by applying pressure to the upper running ball2.5. Corrosion(8 mm in Tests diameter, GCr15 steel, hardness of approximately 59–61 HRC) against the lower Thestationary JB/T 9189-2016 block method in the was reciprocating applied to evaluate mode. the The anti-rust variation performance in fric- of the tion force and displacementJD2000. In with the experiment, time during cast iron the scraps test were of the samecontrolled quality wereusing evenly a computer, spread on the and the entire process was recorded. The test was under a load of 7 N at a frequency of 4 Hz at room temperature (25 °C) and ambient humidity (30.2%) for 30 min. Distilled water and solutions with different concentrations of the JD2000 were adopted as the lubricants. All of the tests were repeated three times.

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filter paper in two culture dishes, and the same amount of water and additive solution were removed with a dropper to evenly wet the iron scraps. After the culture dish was covered, it was kept away from light and humidity for 2 h at room temperature. After the experiment, we removed the iron scraps, rinsed the filter paper with toluene, and dried it in the air. The number and area of rust spots on the filter paper were visually checked to determine the corrosion grade of the additive.

2.6. Water Contact Angle Measurements The DSA30R interfacial rheometer (KRÜSS, Hamburg, Germany) was applied to measure the water contact angle of the additive on different metal surfaces. We ﬁrst submerged the steel plates and aluminum plates used in the tribological test in pure water with or without 2 wt.% JD2000 additive for half an hour at room temperature. The plates were rinsed with toluene and dried in the air, generating the plates for tests. The change of contact angle with time was recorded, and the adsorption rate of lubricant on metal surface was obtained.

2.7. Adsorption Behavior Test of the JD2000 on Metal Surface Q-sense 401 quartz crystal microbalance with dispersion (QCM-D, Biolinscientific, Gothenburg, Sweden) was used to investigate the adsorption behavior of the JD2000 on the metal surface. Compared with iron wafers, which are prone to chemical reactions during the pre-cleaning process and may affect test results, gold wafers can avoid such problems. At the same time, related studies showed that the adsorption behaviors of samples on these two surfaces are consistent. Hence, we adopted the metallographic wafer as the adsorption surface for testing in this study. During the process, the cleaned wafer was placed on the O ring of the QCM-D flow cell and connected to the device. Then, the dodecane solution flowed throughout it at a rate of 80 µL/min. When the ∆F and ∆D curves were stable, we established a baseline and applied the 2 wt.% JD2000 aqueous solution. After the absorption was stable, we waited another 30 min and removed the sample, which then had dodecane flow through it again for about 15 min. At the end of the experiment, the instrument was cleaned with petroleum ether, ethanol, and deionized water. All the data were real-time recorded.

2.8. Characterization of Product Structure and Investigation of Worn Surface To verify the product structure, the Fourier transform infrared (FTIR) spectra were collected using Paragon 1000 (PerkinElmer, Inc., Waltham, MA, USA) with the attenuated total reflection (ATR) attachment scanning from 4000 to 650 cm−1. Nuclear magnetic data were collected with a Bruker AVANCE III HD spectrometer (Bruker, Billerica, MA, USA) in CDCl3 with trimethylsilane as the reference. Measurements were performed with MALDI-TOF MS (Bruker autoflex III, Bruker, Billerica, MA, USA) equipped with a pulsed N2 laser (337 nm). An accelerating voltage of 20 kV was used. The Malvenpanako (Viscotek GPC/SEC, Viscotek Corp, Houston, TX, USA) was used to measure the molecular weight distribution of the additive. The Contour GT (Bruker, Billerica, MA, USA) was used to investigate the morphology (WLI) of the worn surfaces and the wear degree. Prior to the study, the plates were cleaned in an ultrasonic bath with petroleum ether for 10 min and lightly mopped with a clean tissue. To analyze the chemical composition on the worn scars, the X-ray photoelectron spectroscopy (XPS) data were obtained from thermo scientific Escalab 250xi (ESCALAB250Xi, Thermo Fisher Scientific, Waltham, MA, USA) with Al Kα radiation, and the vacuum degree of the analysis chamber was 8 × 10−10 Pa. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy were conducted on AZtec X-MaxN 80 (Oxford, Abingdon, UK), and the Raman spectra were collected using Thermo DXR 2xi (Thermo Fisher Scientific, Waltham, MA, USA) in a range from 3500 to 50 cm−1 with a 532 nm laser source. Coatings 2021, 11, x FOR PEER REVIEW 5 of 20

conducted on AZtec X-MaxN 80 (Oxford, Abingdon, UK), and the Raman spectra were collected using Thermo DXR 2xi (Thermo Fisher Scientific, Waltham, MA, USA) in a range from 3500 to 50 cm−1 with a 532 nm laser source.

3. Results Coatings 2021, 11, 679 5 of 19 3.1. Chemical Structures of the JD2000 Figure 2a shows the FTIR spectra of the JD2000. Sharp peaks near 3030 cm−1 were observed in the FTIR3. spectra Results of the JD2000, which were assigned to the stretching vibration peak of the C–H 3.1.bond Chemical of the Structures benzene of the ring. JD2000 The peaks near 1600 cm−1 were due to the −1 stretching vibration of theFigure –CH2a3 showsbond. the The FTIR stretching spectra of thevibration JD2000. Sharppeak peaksnear near1100 3030 cm cm−1 waswere observed in the FTIR spectra of the JD2000, which were assigned to the stretching vibration assigned to the N=N double bond. The strongest peak at 1170 cm−1 was the stretching peak of the C–H bond of the benzene ring. The peaks near 1600 cm−1 were due to the −1 vibration peak of thestretching C–O–C vibration single ofbond, the –CH pr3ovingbond. Thethe stretching existence vibration of the peak ether near bond 1100 cm ap-was pearing in the spectraassigned of the to JD2000. the N=N The double FTIR bond. results The strongest demonstrate peak at 1170that cm the−1 wasJD2000 the stretching was successfully producedvibration from peakbenzotriazole of the C–O–C singleand bond,formaldehyde. proving the existence Figure of 2b the ethershows bond the appearing 1H in the spectra of the JD2000. The FTIR results demonstrate that the JD2000 was successfully NMR spectra of the JD2000.produced fromThe benzotriazolechemical shif andts formaldehyde. of 7.79 and Figure 7.342 ppmb shows represent the 1H NMR the spectra hy- of drogen atoms in the benzenethe JD2000. ring, The chemical the chemical shifts of shifts 7.79 and of 7.34 4.45 ppm ppm represent represent the hydrogen the signal atoms of in the the active methylenebenzene group, ring, and the a chemical new peak shifts was of 4.45 produced. ppm represent The the peaks signal ofof the 1.0 active and methylene 3.86 ppm represent the methylgroup, and and a new methylene peak was produced. signals Theon peaksthe polyether of 1.0 and 3.86 chain. ppm represent The nuclear the methyl and methylene signals on the polyether chain. The nuclear magnetic resonance data show magnetic resonance datathat the show product that contained the product benzotriazole contained and polyether benzotriazole chains, and and the polyether target product, chains, and the targetJD2000, product, was successfullyJD2000, was obtained. successfully obtained.

Figure 2. The (a) FTIR and (b) 1H NMR spectra of the JD2000. Figure 2. The (a) FTIR and (b) 1H NMR spectra of the JD2000. The structure of the JD2000 product was analyzed using mass spectrometry, as shown in Figure3. The peak at 2334 m/z is the derivative of Jeffamine-triazole at n = 34. The The structure ofdisparity the JD2000 of m/z betweenproduct the was adjacent analyzed peaks is using approximately mass spectrometry, 58, which represents as the shown in Figure 3. Thedifference peak ofat a2334 –C3H 6mO/ structure.z is the derivative GPC results areof shownJeffamine-triazole in the inset’s table. at Then = number34. The disparity of m/z averagebetween molecular the adjacent weight (Mn) peaks is 1055, is andapproximately the weight average 58, molecularwhich represents weight (Mw) is 2234. The degree of dispersion (Mw/Mn) is 2.117. It can be seen that the molecular weight the difference of a –C3H6O structure. GPC results are shown in the inset’s table. The of the JD2000 is concentrated around 2234, and the main degree of polymerization is 34. number average molecularThe results weight show that (Mn) the synthesized is 1055, productand the had aweight polyether average chain structure molecular and was a weight (Mw) is 2234.mixture The degree of derivatives of dispersion with different (Mw/Mn) degrees of is polymerization. 2.117. It can be seen that the molecular weight of the JD2000 is concentrated around 2234, and the main degree of polymerization is 34. The results show that the synthesized product had a polyether chain structure and was a mixture of derivatives with different degrees of polymerization.

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Figure 3. The MS spectra of the JD2000. Figure 3.3.The The MS MS spectra spectra of theof the JD2000. JD2000. 3.2. Configuration3.2. Conﬁguration and Stability and Stability Test Testof the of JD2000 the JD2000 Water-Based Water-Based System System 3.2. Configuration and Stability Test of the JD2000 Water-Based System Due Dueto the to inclusion the inclusion of various of various ions ionsand andimpurities impurities in tap in water, tap water, which which may may affect affect the tribologicalthe tribologicalDue to behavior the behavior inclusion of an of aqueous anof aqueousvarious solution, solution,ions theand water the im waterpurities used used in inthis intap thisexperiment water, experiment which was was may affect distilleddistilledthe tribologicalwater. water. The TheJD2000 behavior JD2000 was of wasintroduced an introducedaqueous into solution, intothe distilled the distilledthe waterwater water andused andultrasonically in ultrasonicallythis experiment was disperseddisperseddistilled in a water. inwater a water bath The bathfor JD2000 30 for s 30to was sobtain to obtainintroduced a uniformly a uniformly into dispersed the dispersed distilled water water solution. water solution. andIn this Inultrasonically this experiment,experiment,dispersed the inJD2000 the a JD2000water aqueous bath aqueous solutionsfor solutions30 s towith obtain with mass mass afractions uniformly fractions of 0.25, ofdispersed 0.25, 0.5, 1, 0.5, 2, 1,waterand 2, and4 wt.% solution. 4 wt.% In this werewereexperiment, prepared. prepared. As the shown As JD2000 shown in Figure aqueous in Figure 4a, the4 solutionsa, aq theueous aqueous with solutions solutions mass of fractions the of theJD2000 JD2000 of with0.25, with different 0.5, different 1, 2, and 4 wt.% concentrations were all clear and diaphanous, and they gradually became pale yellow concentrationswere prepared. were As allshown clear andin Figure diaphanous, 4a, the and aq theyueous gradually solutions became of the pale JD2000 yellow with with different with increasing concentration. To observe their solubility stabilities in water, the JD2000 increasingconcentrations concentration. were all To clear observe and their diaphanous, solubility stabilities and they in water,gradually the JD2000 became aqueous pale yellow aqueoussolutions solutions with with different different concentrations concentrations were were left for left one for month. one month. The results The results are shown are in with increasing concentration. To observe their solubility stabilities in water, the JD2000 shownFigure in 4Figureb. The 4b. JD2000 The aqueousJD2000 solutionsaqueous withsolutions different with concentrations different concentrations remained clear re- and maineddiaphanous,aqueous clear andsolutions and diaphanous, no precipitationwith different and no phenomenon precip concentrationsitation occurred. phenomenon were The left results occurred. for showone month.The that results the The JD2000 results are showstablyshown that the dissolved in JD2000 Figure in stably water,4b. Thedissolved and JD2000 the JD2000 in waaqueouster, aqueous and soluthe solutions JD2000tions with withaqueous different different solutions concentrations concentrations with re- differentweremained concentrations obtained. clear and werediaphanous, obtained. and no precipitation phenomenon occurred. The results show that the JD2000 stably dissolved in water, and the JD2000 aqueous solutions with different concentrations were obtained.

FigureFigure 4. The 4. JD2000The JD2000 aqueous aqueous solutions solutions with withdifferent different concentrations concentrations with withstanding standing time timeof: (a of:) one (a) one day; day;and ( andb) one (b) month. one month.

Figure 4. The JD2000 aqueous solutions with different concentrations with standing time of: (a) one day; and (b) one month.

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3.3. Friction Reduction and Anti-Wear Properties of the Steel Plates To test the anti-friction property of water with JD2000 concentrations ranging from 0 to 4 wt.% on the steel plates, the tribological test was conducted on the UMT-tribolab tester. The test results of the average friction coefficients (COF) of the different concentrations of the JD2000 aqueous solutions are shown in Figure 5a. It can be seen that the COF of the distilled water was 0.481. After adding the lubricant, the COF decreased obviously with increasing amounts of the additive. When the JD2000 concentration was 2 Coatingswt.%,2021, 11 the, 679 COF was 0.185 compared with the distilled water, and the anti-friction prop-7 of 19 erty was improved by 61.4%. When the concentration further increased to 4 wt.%, the COF of the system was 0.182, and the anti-friction property was improved by 62.1%. The COF reduction was 3.3.not Frictionobvious Reduction compared and Anti-Wear with the Properties case of the 2 wt.%. Steel Plates The results show that the lubrication effect of Tothe test JD2000 the anti-friction was sensitive property to of waterits concentration. with JD2000 concentrations The low concentra- ranging from 0 tion JD2000 did not toform 4 wt.% tribofilms. on the steel In plates, this the study, tribological a JD2000 test was concentration conducted on the of UMT-tribolab 2 wt.% was tester. The test results of the average friction coefﬁcients (COF) of the different concentrations of applicable for the JD2000the JD2000 to exert aqueous its solutionslubrication are shownability. in Figure5a. It can be seen that the COF of the To further analyzedistilled the watervariation was 0.481. in the After fricti addingon coefficient the lubricant, during the COF the decreased friction obviously process, with the real-time frictionincreasing coeffici amountsent curves of the of additive. the steel When plates the JD2000 lubricated concentration using was the 2 wt.%, JD2000 the COF was 0.185 compared with the distilled water, and the anti-friction property was improved aqueous solutions areby shown 61.4%. When in Figure the concentration 5b. It can further be seen increased that the to 4 friction wt.%, the coefficient COF of the system of the was distilled water was 0.182,very and unstable the anti-friction and always property fluctuated was improved at by a 62.1%. higher The value. COF reduction When wasthe not JD2000 was added, obviousthe friction compared coefficient with the case and of 2the wt.%. fluctuation The results showof the that friction the lubrication curve effect de- of creased. The averagethe friction JD2000 wascoefficient sensitive todecr its concentration.eased with Theincreasing low concentration amounts JD2000 of the did addi- not form triboﬁlms. In this study, a JD2000 concentration of 2 wt.% was applicable for the JD2000 to tions, and the stabilityexert of its the lubrication curve in ability.creased with increasing concentrations.

Figure 5. The (a) COF and (b) friction coefficient curves of frequency ramp-up reciprocation with the JD2000 concentrations Figure 5. The (a) COF and (b) friction coefficient curves of frequency ramp-up reciprocation with ranging 0–4 wt.% on the steel plates. the JD2000 concentrations ranging 0–4 wt.% on the steel plates. To further analyze the variation in the friction coefficient during the friction process, The wear conditionsthe real-time of the friction steel coefficient plates lubricated curves of the using steel platesthe JD2000 lubricated aqueous using the solu- JD2000 aqueous solutions are shown in Figure5b. It can be seen that the friction coefficient of the tions with different concentrationsdistilled water was are very shown unstable in and Figure always 6. fluctuated It can be at a seen higher that value. the When wear the scar JD2000 width and depth of thewas distilled added, the water friction were coefficient 0.36 and mm the and fluctuation 4.03 μ ofm, the respectively, friction curve decreased.being the The smallest of all the samples.average frictionWith an coefficient increase decreased of the withJD2000 increasing concentrations, amounts of the the additions, width andand the depth of the wear markstability increased of the curve gradually. increased with The increasing results show concentrations. that the water-based lub- The wear conditions of the steel plates lubricated using the JD2000 aqueous solutions ricant JD2000 had nowith anti-wear different concentrationsproperty on are the shown 304 insteel Figure plate.6. It can be seen that the wear scar width and depth of the distilled water were 0.36 mm and 4.03 µm, respectively, being the smallest of all the samples. With an increase of the JD2000 concentrations, the width and depth of the wear mark increased gradually. The results show that the water-based lubricant JD2000 had no anti-wear property on the 304 steel plate.

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Figure 6. 6.The The surface surface curves curves and WLI and morphologies WLI morphologies on the worn disks on the lubricated worn using disks the lubric JD2000ated water using aqueous the solutions JD2000 waterwith different aqueous concentrations: solutions ( awith) 0 wt.%, different (b) 0.25 wt.%,concentrations: (c) 0.5 wt.%, ( d()a 1) wt.%,0 wt.%, (e) 2( wt.%b) 0.25 and wt.%, (f) 4 wt.%. (c) 0.5 wt.%, (d) 1

wt.%, (e) 2 wt.% and (f3.4.) 4 wt.% Friction. Reduction and Anti-Wear Properties of the Aluminum Plates Figure7a shows the COF of the different concentrations of the JD2000 aqueous so- 3.4. Friction Reductionlutions. and Anti-Wear The COF of Properties distilled water of the was Aluminum 0.361. In comparison, Plates with the addition of 0.25, Figure 7a shows0.5, the 1, 2,COF and 4of wt.% the JD2000,different the COFconcentrations decreased to 0.180,of the 0.181, JD2000 0.145, aqueous 0.129, and so- 0.205, respectively. It can be seen that, with the JD2000 concentration of 2 wt.%, the anti-friction lutions. The COF ofproperty distilled was water improved was by 0.361. 64% compared In comparison, with the distilled with the water. addition However, of when 0.25, the 0.5, 1, 2, and 4 wt.%concentration JD2000, the was COF further decreased increased to to 4 wt.%, 0.180, the 0.181, COF of the0.145, system 0.129, increased. and The0.205, results respectively. It can beshow seen that that, the lowwith JD2000 the JD concentrations2000 concentration were unable of to2 wt.%, form tribofilms, the anti-friction while a high additive concentration caused an excess of long chains in the water that generated the property was improvedaggregation by 64% complication compared and with increased the friction.distilled Therefore, water. in However, this study, the when JD2000 the with concentration was furtherconcentration increased of 2 wt.% to was4 wt.%, applicable the COF for the of JD2000 the system to exert its increased. lubrication ability.The results show that the lowTo JD2000 further analyzeconcentrations the variation were in the unable friction coefficientto form duringtribofilms, the friction while process, a high additive concentrationthe real-time caused friction an coefficient excess of curves long lubricated chains in using the the water JD2000 that aqueous generated solutions on the surface of the steel plates are shown in Figure7b. It can be seen that the friction the aggregation complicationcoefficient of and the distilled increased water friction. was very unstableTherefore, and always in this fluctuated study, atthe a higher JD2000 value. with concentration ofWhen 2 wt.% a small was amount applicable of the JD2000 for the (0.25 JD2000 and 0.5 to wt.%) exert was its introduced lubrication into theability. distilled To further analyzewater, the the variation fluctuation in and the the fricti frictionon coefficient coefficient of the during aqueous the solutions friction decreased. process, This the real-time frictioncan coefficient be attributed curves to the lubr aluminumicated plate using being the less JD2000 rigid than aqueous the steel solutions balls. During on the friction process, the rough surface directly contacted and sheared mutually under the the surface of the steelsqueezing plates action, are shown making in the Figu soft aluminumre 7b. It platecan be easily seen produce that metalthe friction debris. This coef- led to ficient of the distilledabrasive water and was adhesive very wear,unstable and the and friction always coefficient fluctuated increased at rapidly. a higher Then, value. a portion When a small amountof theof debristhe JD2000 was extruded (0.25 and from 0.5 the frictionwt.%) orbitwas andintroduced entered the into surrounding the distilled aqueous solution system, and the friction coefficient decreased accordingly. This process was water, the fluctuation and the friction coefficient of the aqueous solutions decreased. This can be attributed to the aluminum plate being less rigid than the steel balls. During the friction process, the rough surface directly contacted and sheared mutually under the squeezing action, making the soft aluminum plate easily produce metal debris. This led to abrasive and adhesive wear, and the friction coefficient increased rapidly. Then, a portion of the debris was extruded from the friction orbit and entered the surrounding aqueous solution system, and the friction coefficient decreased accordingly. This process was repeated throughout the friction testing process, making the friction curve of the distilled water and a lower concentration of the JD2000 aqueous solutions change periodically. When the concentrations of the JD2000 increased to 1 and 2 wt.%, it was observed that the friction curve had no obvious fluctuation and remained at the lowest point. The friction coefficient of the 2 wt.% JD2000 aqueous solutions was very stable and

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repeated throughout the friction testing process, making the friction curve of the distilled stayed at the lowestwater value, and showing a lower concentration that the JD2000 of the had JD2000 the aqueous best anti-friction solutions change property periodically. at 2 wt.%. When the concentrationWhen the concentrations of the JD2000 of the JD2000 was increasedincreased to 1to and 4 2wt.%, wt.%, the it was friction observed curve that the friction curve had no obvious fluctuation and remained at the lowest point. The friction resumed its periodiccoefficient fluctuation, of the 2 and wt.% JD2000the fricti aqueouson coefficient solutions was also very increased. stable and stayed It is at specu- the lowest lated that this was becausevalue, showing the appropriate that the JD2000 concentration had the best anti-friction of the JD2000 property could at 2 wt.%. well Whencover the the surface of the aluminumconcentration plates, of the JD2000 forming was increaseda stable tofriction 4 wt.%, thefilm friction and curvepreventing resumed itsthe periodic di- fluctuation, and the friction coefficient also increased. It is speculated that this was because rect contact of the roughthe appropriate surface. concentration When the am of theount JD2000 of additive could well continued cover the surface to increase, of the aluminum the thickness of the lubricationplates, forming film a stableincreased, friction filmwhich and preventingtended to the form direct an contact agglomeration of the rough surface. of molecular chains. ThisWhen led the to amount an increase of additive in the continued friction to increase,coefficient. the thickness of the lubrication film increased, which tended to form an agglomeration of molecular chains. This led to an increase in the friction coefficient.

Figure 7. The (a) COF and (b) friction coefficient curves of frequency ramp-up reciprocation with the JD2000 concentrations rangingFigure 0–4 7. wt.%The on(a) the COF aluminum and (b plates.) friction coefficient curves of frequency ramp-up reciprocation with the JD2000 concentrations ranging 0–4 wt.% on the aluminum plates. The 3D topography and the profile depth curve of the wear marks on the surface of The 3D topographythe aluminum and the plates profile after thedepth friction curve test areof shownthe wear in Figure marks8. It canon bethe clearly surface observed of that the surface of the aluminum plates was heavily worn after the distilled water friction, the aluminum plateswith after a width the of friction approximately test ar 3.1e mmshown and ain depth Figure of 92.5 8.µ Itm. can After be the clearly addition ob- of the served that the surfaceJD2000 of the lubricant, aluminum the wear plat amountes was decreased heavily significantly, worn after and the the distilled width and water depth of friction, with a widthwear of marksapproximately decreased gradually 3.1 mm with and an a increase depth in of the 92.5 JD2000 μm. addition. After the With addition the addition of the 2 wt.% JD2000 in water, the width and depth of the abrasion mark were 0.7 mm of the JD2000 lubricant,and 2.3 theµm, wear which wereamount reduced decreased by 77.4% andsignificantly, 97.5%, respectively, and the compared width with and that depth of wear marksof thedecreased distilled water,gradually greatly with improving an increase the friction in and the wear JD2000 phenomenon addition. of the With water the addition of the system.2 wt.% With JD2000 this result in water, combined the with width the real-time and depth friction of coefficient the abrasion curves, mark it can be were 0.7 mm and 2.3concluded μm, which that the were 2 wt.% reduced JD2000 water by dispersion77.4% and had the97.5%, best comprehensiverespectively, lubrication com- performance of all the samples. pared with that of the distilledThe wear volumewater, atgreatly the wear improving mark on the the aluminum friction plates and with wear different phenom- concen- enon of the water system.trations With of the this JD2000 result water co solutionsmbined after with the the tribological real-time experiment friction were coefficient calculated. curves, it can be concludedThe results that are as the shown 2 wt.% in Figure JD20009. With water an increase dispersion in the concentration had the ofbest the additive,com- the wear volume gradually decreased. It can be seen that the wear volume of the distilled prehensive lubricationwater performance was 0.034 mm 2of. With all the the additionsamples. of 2 wt.% JD2000 in the water, the wear volume of the abrasion mark was 0.004 mm2, which was reduced by 88.2% compared with that of the distilled water. Therefore, the JD2000 had an excellent anti-wear property on the aluminum plate.

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Figure 8. The surface curves and WLI morphologies on worn disks lubricated by the JD2000 water aqueous solutions with different concentrations: (a) 0 wt.%, (b) 0.25 wt.%, (c) 0.5 wt.%, (d) 1 wt.%, (e) 2 wt.% and (f) 4 wt.%.

The wear volume at the wear mark on the aluminum plates with different concentrations of the JD2000 water solutions after the tribological experiment were calculated. The results are as shown in Figure 9. With an increase in the concentration of the additive, the wear volume gradually decreased. It can be seen that the wear volume of the distilled water was 0.034 mm2. With the addition of 2 wt.% JD2000 in the water, the wear volume of the abrasion mark was 0.004 mm2, which was reduced by 88.2% compared FigureFigure 8. 8.The The surface surface curves curveswith and WLIthat and morphologiesof the WLI distilled morphologies on water. worn Therefore, disks on lubricated worn the JD2000 bydisks the JD2000had lubricated an waterexcellent aqueousby anti-wear the solutionsJD2000 property withwater on the aluminum plate. differentaqueous concentrations: solutions with (a) 0 wt.%,different (b) 0.25 concentrations: wt.%, (c) 0.5 wt.%, (a (d)) 0 1 wt.%,wt.%, (e )(b 2) wt.% 0.25 and wt.%, (f) 4 wt.%.(c) 0.5 wt.%, (d) 1 wt.%, (e) 2 wt.% and (f) 4 wt.%.

Figure 9. TheThe wear wear volume volume of the of thewater water scar scarlubricat lubricateded by the by JD2000 the JD2000 aqueous aqueous solutions solutions with dif- with differentferent concentrations concentrations on the on aluminum the aluminum plates plates measured measured usingusing the UMT the UMTtribometer. tribometer.

3.5. Anti-Corrosion and Anti-Rust Property The results of corrosion tests are shown in Figure 10. Corrosion grades were assigned according to the JB/T 9189-2016. It can be observed that, when the distilled water was used as anti-rust solution, the surface rust area of filter paper was more than 5%, which belongs to severe corrosion. When the 2 wt.% JD2000 aqueous solution was used as anti- rust solution, the surface rust area of filter paper was between 1% and 5%, belonging to moderate corrosion. Comparing the area of rust spots produced by the two kinds of anti-rust solutions, it can be seen that the addition of the JD2000 can reduce the corrosion degree by about 75.5%, which has significant anti-rust performance.

Figure 9. The wear volume of the water scar lubricated by the JD2000 aqueous solutions with different concentrations on the aluminum plates measured using the UMT tribometer.

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3.5. Anti-Corrosion and Anti-Rust Property The results of corrosion tests are shown in Figure 10. Corrosion grades were assigned according to the JB/T 9189-2016. It can be observed that, when the distilled water was used as anti-rust solution, the surface rust area of filter paper was more than 5%, which belongs to severe corrosion. When the 2 wt.% JD2000 aqueous solution was used Coatings 2021, 11, x FOR PEER REVIEW 11 of 20 as anti-rust solution, the surface rust area of filter paper was between 1% and 5%, belonging to moderate corrosion. Comparing the area of rust spots produced by the two kinds of anti-rust solutions,3.5. Anti-Corrosion it can be and seen Anti-Rust that Propertythe addition of the JD2000 can reduce the corrosion degree by aboutThe 75.5%, results whichof corrosion has significanttests are shown anti-rust in Figure performance. 10. Corrosion grades were assigned according to the JB/T 9189-2016. It can be observed that, when the distilled water was used as anti-rust solution, the surface rust area of filter paper was more than 5%, which belongs to severe corrosion. When the 2 wt.% JD2000 aqueous solution was used as anti-rust solution, the surface rust area of filter paper was between 1% and 5%, be- Coatings 2021, 11, 679 longing to moderate corrosion. Comparing the area of rust spots produced by the11 oftwo 19 kinds of anti-rust solutions, it can be seen that the addition of the JD2000 can reduce the corrosion degree by about 75.5%, which has significant anti-rust performance.

Figure 10. The results of corrosion tests with (a) distilled water and (b) 2 wt.% JD2000 as anti-rust agent.

3.6. Lubrication Mechanisms 3.6.1. Analysis of WaterFigureFigure Contact 10.10. TheThe results resultsAngle of of corrosionMeasurements corrosion tests tests with with ( aResults ()a distilled) distilled water water and and (b) ( b2 )wt.% 2 wt.% JD2000 JD2000 as anti-rust as anti- rustagent. agent. The ability to adsorb onto a metal surface is essential to the effectiveness of additives. Water contact3.6.3.6. angle LubricationLubrication measurements MechanismsMechanisms were performed to evaluate the adsorption 3.6.1. Analysis of Water Contact Angle Measurements Results behavior of polar molecules3.6.1. Analysis on ofthe Water metal Contact surface Angle (Figure Measurements 11a–d). Results The results show that The ability to adsorb onto a metal surface is essential to the effectiveness of additives. the contact angles of theThe surfaces ability to decreasedadsorb onto witha metal the surface addition is essential of the to the JD2000 effectiveness additive, of addi- Watertives. contactWater contact angle measurements angle measurements were performed were performed to evaluate to theevaluate adsorption the adsorption behavior which contained multipleofbehavior polar surface molecules of polar active molecules on the metalnitrog on surfacetheen metalatoms (Figure su rface[9]. 11 a–d). This(Figure The is 11a–d).because results The show the results that nitrogen the show contact that atoms can combine anglesthewith contact ofthe the anglesmetal surfaces ofsurface decreased the surfaces el withements, decreased the addition forming with of the a JD2000addition firm additive,adsorption of the whichJD2000 layer, contained additive, which can still existmultiple whichon the contained surfacemetal active multiplesurface nitrogen surfaceafter atoms rinsing.active [9]. nitrog This In is enthe because atoms contact [9]. the nitrogenThis angle is because atomstest, canthe combine nitrogenhy- withatoms the can metal combine surface with elements, the metal forming surface a firmelements, adsorption forming layer, a firm which adsorption can still layer, exist drophilic group of theon theJD2000 metal can surface combine after rinsing. with In water, the contact andangle the water test, the spreads hydrophilic out group on the of the which can still exist on the metal surface after rinsing. In the contact angle test, the hy- JD2000 can combine with water, and the water spreads out on the metal surface, resulting metal surface, resultingdrophilic in the group reduction of the JD2000 of contact can combine angles. with Thewater, adsorption and the water curve spreads (Figure out on the in the reduction of contact angles. The adsorption curve (Figure 11e) shows that the JD2000 11e) shows that the JD2000metal surface, lubricant resulting spreads in the reductionfaster on of the contact metal angles. surface The adsorption and forms curve a film (Figure lubricant spreads faster on the metal surface and forms a film rapidly (as illustrated in the rapidly (as illustrated11e) in showsthe inset), that the which JD2000 ve lubricantrifies thespreads conjecture faster on theof adsorptionmetal surface film.and forms a film inset), which verifies the conjecture of adsorption film. rapidly (as illustrated in the inset), which verifies the conjecture of adsorption film.

Figure 11. Aqueous contact angle goniometry dip-coated with: (a) distilled water on the steel plates; (b) 2 wt.% JD2000 on the steel plates; (c) distilled water on the aluminum plates; and ( d) 2 Figure 11. Aqueous contactwt.% angle JD2000 goniometry on the dip-coated aluminum with:plates. (a ()e distilled) The adsorption water on curves. the steel plates; (b) 2 wt.% JD2000 Figureon the steel 11. plates; Aqueous (c) distilled contact water angle on the goniometry aluminum plates; dip-coated and (d) 2 wt.% with: JD2000 (a) ondistilled the aluminum water plates. on the (e) Thesteel plates;adsorption (b) curves. 2 wt.% JD2000 on the steel plates; (c) distilled water on the aluminum plates; and (d) 2 wt.% JD2000 on the aluminum plates. (e) The adsorption curves. 3.6.2. Analysis of Adsorption Behavior Results The change in frequency (∆f) depends on the quantity of the molecules adsorbed on the surface of the wafer. It can be seen that, with the adsorption of the JD2000 on the surface, ∆f of the wafer surface increased signiﬁcantly (Figure 12a), indicating that the

adsorption rate was greater than the desorption rate; the curve was stable after 15,000 s, indicating that the absorption/desorption rate had reached equilibrium at this time. After the surface was rinsed with dodecane, the curve had no obvious change, implying that the adsorption of the JD2000 on the metal surface was highly stable. The change in energy dissipation factor (∆D) reflects the internal viscoelasticity and structural changes of the substance. When ∆D < 10−6, it means that a rigid film is formed on the surface, and when ∆D > 10−6, a viscoelastic film is formed on the surface. As shown in Figure 12b, after Coatings 2021, 11, x FOR PEER REVIEW 12 of 20

3.6.2. Analysis of Adsorption Behavior Results The change in frequency (∆f) depends on the quantity of the molecules adsorbed on the surface of the wafer. It can be seen that, with the adsorption of the JD2000 on the surface, ∆f of the wafer surface increased significantly (Figure 12a), indicating that the adsorption rate was greater than the desorption rate; the curve was stable after 15,000 s, indicating that the absorption/desorption rate had reached equilibrium at this time. After the surface was rinsed with dodecane, the curve had no obvious change, implying that the adsorption of the JD2000 on the metal surface was highly stable. The change in energy Coatings 2021, 11, 679 dissipation factor (∆D) reflects the internal viscoelasticity and structural changes of the12 of 19 substance. When ∆D < 10−6, it means that a rigid film is formed on the surface, and when ∆D > 10−6, a viscoelastic film is formed on the surface. As shown in Figure 12b, after adsorption on the surface, the elastic modulus of the JD2000 increased and far exceeded 10adsorption−6, showing on that the the surface, JD2000 the formed elastic a typical modulus visc ofoelastic the JD2000 film on increased the surface, and which far exceeded kept − 10the 6film, showing intact without that the fracture JD2000 formedunder the a typicalaction of viscoelastic experimental ﬁlm load on theand surface, provided which long-termkept the ﬁlm lubrication intact without protection fracture for the under metal thesurface. action of experimental load and provided long-term lubrication protection for the metal surface.

Figure 12. 12. (a(a) )Frequency Frequency variation variation curve curve and and (b) (energyb) energy dissipation dissipation factor factor variation variation curve curveof the of2 the wt.%2 wt.% JD2000 JD2000 aqueous aqueous solution solution on the on themetal metal surface. surface. 3.6.3. Analysis of the Worn Surfaces of Steel Plates 3.6.3. Analysis of the Worn Surfaces of Steel Plates ToTo further investigate investigate the the we wearar surfaces surfaces of ofthe the aluminum aluminum plates, plates, the theoverall overall SEM SEM images were recorded, as shown in Figure 13. Figure 13a –a shows the surface morphol- images were recorded, as shown in Figure 13. Figure 13a11–a3 shows the surface mor- phologyogy of the of wearthe wear marks marks with with different different water water lubrication lubrication under under different different magnifications.magnifica- Figure 13b –b shows the surface morphologies of the wear marks under different magni- tions. Figure1 13b3 1–b3 shows the surface morphologies of the wear marks under different magnificationsfications with thewith 2 the wt.% 2 wt.% JD2000 JD2000 lubrication. lubrication. The The SEM SEM of the of the wear wear surface surface with with a higher a highermagnification magnification is shown is shown on the on left the side left to side give to more give detailsmore details of the wearof the surface.wear surface. When the WhenSEM images the SEM of images the wear of surfacesthe wear weresurfaces viewed were atviewed the same at the magnification, same magnification, it was clearly it wasshown clearly that theshown JD2000 that correspondedthe JD2000 corresponded to a smaller wearto a smaller volume wear compared volume with compared the distilled water.with the It distilled can be seenwater. that It can the be surfaces seen that of the the surfaces steel plates of the were steel severely plates were worn severely under the worndistilled under water the lubrication,distilled water with lubrication, obvious with grooves obvious and grooves bumps. and In addition,bumps. In tiny addi- metal tion,fragments tiny metal were fragments distributed were on thedistributed wear track. on the The wear surfaces track. were The verysurfaces coarse were because very of coarsethe experimental because of load.the experimental Direct contact load. between Direct contact the surfaces between of the the friction surfaces pairs of the resulted fric- in tionmutual pairs shearing, resulted andin mutual the friction shearing, between and the the friction rough between surfaces the made rough the surfaces surface made particles peelthe surface off. This particles in turn peel led tooff. the This wear in ofturn the led abrasive to the particles,wear of the resulting abrasive in particles, a higher frictionre- sultingcoefficient. in a higher With the friction addition coefficient. of the additive,With the addition the surface of the quality additive, was improved,the surface and qualitysmooth was surfaces improved, with noand metal smoot debris,h surfaces basically with no no metal grooves debris, and basically bumps, andno grooves only slight andscratches bumps, were and obtained. only slight In scratches addition, were the marksobtained. of the In tribofilmsaddition, the filling marks can of be the observed. tri- Thisbofilms could filling be can attributed be observed. to the This better could adsorption be attributed of the to active the better elements adsorption in the JD2000of the on the surfaces, which formed a sheared film during the friction process and avoided direct contact between the metal surfaces of the friction pair. To analyze the formation of the friction film on the steel surface under the 2 wt.% JD2000 lubrication condition, the MS of the JD2000 (Figure4) and the friction-tested steel

plates (Figure 14) were compared. When the m/z values appeared near 567 and 854, it was speculated that this molecule was a JD2000 long chain that lost C6H4N3CH2NH– and CH3–, and its degree of polymerization was 7 and 12, respectively. When the m/z value appeared near 642, the corresponding molecule was the additive long chain with a lost C6H4N3CH2NH– structure, and the degree of polymerization was 8. The results show that the chemical bonds of the JD2000 molecular long chain broke and formed long chains with different molecular weights. These would cover the worn surface and further participate in the formation of the lubricating ﬁlm, ﬁlling the wear marks. Hence, during the friction process, they would play a protective role in preventing metal debris and more serious wear. Coatings 2021, 11, x FOR PEER REVIEW 13 of 20

active elements in the JD2000 on the surfaces, which formed a sheared film during the friction process and avoided direct contact between the metal surfaces of the friction pair.

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Coatings 2021,active11, 679 elements in the JD2000 on the surfaces, which formed a sheared film during the 13 of 19 friction process and avoided direct contact between the metal surfaces of the friction pair.

Figure 13. SEM images of the wear scar on the steel surface with: (a1–a3) the distilled water; and (b1–b3) the 2 wt.% JD2000 aqueous solution.

To analyze the formation of the friction film on the steel surface under the 2 wt.% JD2000 lubrication condition, the MS of the JD2000 (Figure 4) and the friction-tested steel plates (Figure 14) were compared. When the m/z values appeared near 567 and 854, it was speculated that this molecule was a JD2000 long chain that lost C6H4N3CH2NH– and CH3–, and its degree of polymerization was 7 and 12, respectively. When the m/z value appeared near 642, the corresponding molecule was the additive long chain with a lost C6H4N3CH2NH– structure, and the degree of polymerization was 8. The results show that the chemical bonds of the JD2000 molecular long chain broke and formed long chains with different molecular weights. These would cover the worn surface and further participate in the formation of the lubricating film, filling the wear marks. Hence, during the Figure 13. SEM images of thefriction wear scar process, on the steelthey surface would with: play (a a– protectivea ) the distilled role water; in preventing and (b –b metal) the 2 debris wt.% JD2000 and more Figure 13. SEM images of the wear scar on the steel surface1 3 with: (a1–a3) the distilled1 3 water; and aqueous solution. serious wear. (b1–b3) the 2 wt.% JD2000 aqueous solution.

To analyze the formation of the friction film on the steel surface under the 2 wt.% JD2000 lubrication condition, the MS of the JD2000 (Figure 4) and the friction-tested steel plates (Figure 14) were compared. When the m/z values appeared near 567 and 854, it was speculated that this molecule was a JD2000 long chain that lost C6H4N3CH2NH– and CH3–, and its degree of polymerization was 7 and 12, respectively. When the m/z value appeared near 642, the corresponding molecule was the additive long chain with a lost C6H4N3CH2NH– structure, and the degree of polymerization was 8. The results show that the chemical bonds of the JD2000 molecular long chain broke and formed long chains with different molecular weights. These would cover the worn surface and further participate in the formation of the lubricating film, filling the wear marks. Hence, during the friction process, they would play a protective role in preventing metal debris and more serious wear. FigureFigure 14.14. TheThe MSMS spectraspectra ofof thethe friction-testedfriction-tested steelsteel platesplates lubricatedlubricated byby thethe 22 wt.%wt.% JD2000JD2000 aque-aque- ousous solution.solution.

TheThe differentdifferent element element contents contents of theof the wear we marksar marks were were obtained obtained using EDS,using as EDS, shown as inshown Table in1. ItTable can be1. It observed can be observed that, when that, the when distilled the water distilled was water used aswas the used lubricant, as the thelub- mostricant, abundant the most element abundant in theelement wear in marks the we wasar Fe,marks which was came Fe, which from thecame metal from material the metal of the friction pair and the wear debris produced during the friction process. C, Si, Cr, Ni, and Mn came from the inner material of the friction pair. When the JD2000 was introduced into the water, the worn surface containing N and O elements was derived from the JD2000, showing that the long chain JD2000 passed through the reactive elements and reacted with the metal surface. They then adhered to the surface stably and formed the protective ﬁlm. In addition, the Mn element was only produced during the process of water friction, while its existence was not detected under the JD2000 lubrication. This indicated that the friction pair under water lubrication was seriously worn, and the wear was reduced after the addition of the JD2000.

Table 1. Element contents of the friction-tested steel plate. Figure 14. The MS spectra of the friction-tested steel plates lubricated by the 2 wt.% JD2000 aqueous solution.Statistics (wt.%) C N O Si Cr Ni Mn Fe worn surfaces under distilled water 1.08 0 0 0.23 16.62 8.74 1.14 72.19 worn surfaces underThe 2different wt.% JD2000 element aqueous contents solution of 1.7 the we 7.64ar marks 3.89 were 0.58 obtained 17.16 using 6.36 EDS, 0as 62.67 shown in Table 1. It can be observed that, when the distilled water was used as the lubricant, the most abundant element in the wear marks was Fe, which came from the metal

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To further investigate the chemical composition of the tribofilms and illustrate the changes in the chemical states of the several typical elements on the worn surfaces, the composition of the wear marks on the steel plate after the friction test was analyzed using XPS. Figure 15 shows the high-resolution XPS spectra of C1s, O1s, Fe2p, and N1s. All of the XPS spectra were fitted using the Lorentzian–Gaussian method. The C1s spectra of the surface have a weak peak at 285.1 eV, which represents the C–O chemical bond. There are two new peaks in the C1s spectra of the lubricating film formed by the JD2000, and the peaks at 288.5 and 286.1 eV represent the C=O and C–C bonds of the lubricating film, respectively. These results indicate that the hydrocarbon compounds were absorbed tribo-physically on the worn surface. The peak of O1s at 531.0 eV came from the SiO2, and the additive-containing lubricant also contained NiO bonds in the friction film formed during friction. The peak of the Fe2p spectra at 708.3 eV corresponds to the binding energy of FeOOH. In addition, the binding energy peak at 705.7 and 718.8 eV correspond to Fe2p3 and Fe2p1, respectively, while the new signal peak at 76.5 eV is assigned to the Fe2O3, which was one of the components of the surface friction film. The spectra results of the N elements show that the active nitrogen elements in the additive also adsorbed on the surface of the steel plate, producing the binding energy peak of the N–O bond at 399.3 eV. Coatings 2021, 11, x FOR PEER REVIEW This made the long chain in the JD2000 bind tightly to the surface of the steel plate during 15 of 20 the friction process, and thus it played a protective role to prevent direct contact between the metal friction pairs.

FigureFigure 15. 15. TheThe XPS XPS spectraspectra of of (a )( C1s,a) C1s, (b) O1s,(b) O1s, (c) Fe2p (c) and Fe2p (d) and N1s on(d) the N1s wear on scar the of wear the steel scar ball of the steel ball lubricatedlubricated using using the 22 wt.% wt.% JD2000 JD2000 aqueous aqueous solution solu astion measured as measured using the UMTusing tribometer. the UMT tribometer.

3.6.4. Analysis of the Worn Surfaces of Aluminum Plates To further investigate the wear surfaces of aluminum plates, the SEM images of the surface wear of the aluminum plates obtained by lubrication with distilled water and the 2 wt.% JD2000 were compared under the same test conditions. Figure 16a1–a3 shows the surface morphologies of the wear marks with the water lubrication under different magnifications. It can be seen that, under the distilled water lubrication, the surface of the aluminum plates was severely worn, and there were a large amount of wear debris and obvious cutting pits in the wear track. The surface was very rough, showing that the direct contact of the rough friction pairs caused surface particles to peel off and contribute a large amount of metal debris. This led to the deep and wide cutting pits. Figure 16b1–b3 shows the wear marks of the 2 wt.% JD2000 lubrication under different magnifications. After adding the additive, the surface of the wear marks was smooth, with no obvious metal debris particles and grooves. However, it can be observed that the surface of the aluminum plates was covered with a thin layer of film, and the spalling lubricating film fragments can be clearly seen at a large multiple. This indicated that the JD2000 reacted with the metal surface during the friction process and produced the protected film. The fragments were produced when the chemical film was sheared during the friction process, which filled in the abrasion mark, avoided direct contact with the metal surface, and played an obvious lubrication role.

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3.6.4. Analysis of the Worn Surfaces of Aluminum Plates To further investigate the wear surfaces of aluminum plates, the SEM images of the surface wear of the aluminum plates obtained by lubrication with distilled water and the 2 wt.% JD2000 were compared under the same test conditions. Figure 16a1–a3 shows the surface morphologies of the wear marks with the water lubrication under different magnifications. It can be seen that, under the distilled water lubrication, the surface of the aluminum plates was severely worn, and there were a large amount of wear debris and obvious cutting pits in the wear track. The surface was very rough, showing that the direct contact of the rough friction pairs caused surface particles to peel off and contribute a large amount of metal debris. This led to the deep and wide cutting pits. Figure 16b1–b3 shows the wear marks of the 2 wt.% JD2000 lubrication under different magnifications. After adding the additive, the surface of the wear marks was smooth, with no obvious metal debris particles and grooves. However, it can be observed that the surface of the aluminum plates was covered with a thin layer of film, and the spalling lubricating film fragments can be clearly seen at a large multiple. This indicated that the JD2000 reacted with the metal surface during the friction process and produced the protected film. The fragments were Coatings 2021, 11, x FOR PEER REVIEW produced when the chemical film was sheared during the friction process,16 of which 20 filled in the abrasion mark, avoided direct contact with the metal surface, and played an obvious lubrication role.

FigureFigure 16. The 16. SEM The images SEM ofimages the wear of the scar wear on the scar aluminum on the aluminum plates with: plates (a1–a3 )with: the distilled (a1–a3) water;the distilled and (b1 wa-–b3) the 2 wt.% JD2000ter; and aqueous (b1–b3) solution. the 2 wt.% JD2000 aqueous solution. Figure 17 shows the MS of the friction-tested aluminum plates under the 2 wt.% Figure 17 showsJD2000 the lubrication MS of the condition. friction-tested It can be aluminum seen that the plates polymer under can bethe detected 2 wt.% at the wear JD2000 lubricationplace condition. of the aluminum It can be platesseen th afterat the lubrication polymer with can thebe detected JD2000, and at the the wear results are very place of the aluminumsimilar plates to those after of thelubricatio steel plates.n with When the theJD2000,m/z values and the were results near 569are andvery 855, it was similar to those ofspeculated the steel thatplates. this When molecule the was m/z a values JD2000 were long chainnear 569 that and lost C855,6H4 Nit 3wasCH2 NH– and speculated that thisCH molecule3–, and its wa degreess a JD2000 of polymerization long chain that were lost 7 and C6 12.H4N When3CH2 theNH–m /andz value CH was3–, near 649, and its degrees ofthe polymerization corresponding were molecule 7 and was 12. the When additive the long m/z chainvalue with was the near lost 649, C6H the4N 3CH2NH– structure, and the degree of polymerization was 8. The results show that the chain of the corresponding molecule was the additive long chain with the lost C6H4N3CH2NH– JD2000 molecule broke and formed chains with different molecular weights during the structure, and the degree of polymerization was 8. The results show that the chain of the friction process. This then ﬁlled in the wear track to prevent direct contact with the uneven JD2000 molecule metalbroke surface. and formed chains with different molecular weights during the friction process. This then filled in the wear track to prevent direct contact with the uneven metal surface.

Figure 17. The MS spectra of the friction-tested aluminum plates lubricated using the 2% JD2000 aqueous solution.

The wear marks obtained by lubrication with the distilled water and 2 wt.% JD2000 under the same test conditions of the aluminum plates were analyzed using EDS, and the different element contents of the friction film were obtained. The results are shown in Table 2. When the distilled water was used as the lubricating fluid, the content of Al in the wear mark was as great as 74.2%, which is the primary component of the wear mark surface. In addition, it also contained a small amount of O and Mg, which came from the water and friction material, respectively. When the JD2000 was added into the water, the primary elements of the abrasion mark were Al, O, and C, and a portion of the C and O elements came from the JD2000. In addition, the primary composition of the friction film

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Figure 16. The SEM images of the wear scar on the aluminum plates with: (a1–a3) the distilled water; and (b1–b3) the 2 wt.% JD2000 aqueous solution.

Figure 17 shows the MS of the friction-tested aluminum plates under the 2 wt.% JD2000 lubrication condition. It can be seen that the polymer can be detected at the wear place of the aluminum plates after lubrication with the JD2000, and the results are very similar to those of the steel plates. When the m/z values were near 569 and 855, it was speculated that this molecule was a JD2000 long chain that lost C6H4N3CH2NH– and CH3–, and its degrees of polymerization were 7 and 12. When the m/z value was near 649, the corresponding molecule was the additive long chain with the lost C6H4N3CH2NH– structure, and the degree of polymerization was 8. The results show that the chain of the

Coatings 2021, 11, 679 JD2000 molecule broke and formed chains with different molecular weights during16 of the 19 friction process. This then filled in the wear track to prevent direct contact with the uneven metal surface.

Figure 17.17. TheThe MSMS spectraspectra ofof thethe friction-testedfriction-tested aluminumaluminum platesplates lubricatedlubricated usingusing thethe 2%2% JD2000JD2000 aqueousaqueous solution.solution.

The wearwear marksmarks obtainedobtained byby lubricationlubrication withwith thethe distilleddistilled waterwater andand 22 wt.%wt.% JD2000JD2000 under thethe samesame testtest conditionsconditions ofof thethe aluminumaluminum platesplates werewere analyzedanalyzed usingusing EDS,EDS, andand thethe different elementelement contentscontents ofof thethe frictionfriction filmfilm werewere obtained.obtained. The resultsresults areare shownshown inin TableTable2 2.. WhenWhen thethe distilled distilled waterwater waswas used used asas the the lubricating lubricating fluid, fluid, the the content content of of Al Al in in thethe wearwear markmark waswas asas greatgreat asas 74.2%,74.2%, whichwhich isis thethe primaryprimary componentcomponent ofof thethe wearwear markmark surface.surface. In addition, it also containedcontained aa smallsmall amountamount ofof OO andand Mg,Mg, whichwhich camecame fromfrom thethe waterwater andand frictionfriction material,material, respectively.respectively. WhenWhen thethe JD2000JD2000 waswas addedadded intointo thethe water,water, thethe primaryprimary elementselements of the abrasionabrasion mark were Al, O,O, andand C,C, andand aa portionportion ofof thethe CC andand OO elementselements camecame fromfrom thethe JD2000.JD2000. InIn addition,addition, thethe primaryprimary compositioncomposition ofof thethe frictionfriction filmfilm on the aluminum plate was the stable chemical bond, which formed due to the reaction of the O and C elements in the JD2000 with the metal surface.

Table 2. Element contents of the friction-tested aluminum plate.

Statistics (wt.%) O Mg Al C worn surfaces under distilled water 23.25 2.56 74.20 0 worn surfaces under 2 wt.% JD2000 aqueous solution 30.33 1.40 44.35 23.82

To further investigate the chemical composition of the triboﬁlms and describe the lubrication mechanism of the JD2000, the compositions of the wear marks on the aluminum plates after the friction test were analyzed using XPS. Figure 18 shows the high-resolution XPS spectra of O1s, Al2p, C1s and N1s, illustrating the changes in the chemical states of several typical elements on the worn surfaces. All the high-resolution XPS spectra were ﬁtted using the Lorentzian–Gaussian method. The Al2p and O1s spectra of the worn surfaces under the two lubrication types were analogous. The weak peaks at 74.2 eV for Al2p and Al2p signal intensity of the JD2000 were slightly stronger, which came from the reaction of the Al element with O during the friction process. The O in the JD2000 molecule promoted the formation of a more stable Al–O bond on the metal surface. The O1s spectra of both were at 531 eV, and the signal peaks at 532.8 and 532.8 eV were from Mg–O and Al–O, respectively. The peak of the JD2000 was slightly higher, which indicated that the oxygen element in the JD2000 also participated in the formation of the chemical bond. The peaks of the C1s spectra of the JD2000 at 284.6 and 285.6 eV came from the C–C and C–O bonds, respectively. The spectra of the N elements showed that the active nitrogen elements in the additive reacted with aluminum to produce the binding energy peak of the Al–N bond at 398.2 eV. This makes the long chain in the JD2000 bind tightly to the surface of the steel plate during the friction process and play a protective role in preventing direct contact between the metal friction pairs. This demonstrated that the long chain structure Coatings 2021, 11, 679 17 of 19

Coatings 2021, 11, x FOR PEER REVIEW 18 of 20 of the JD2000 molecules was part of the friction ﬁlm, which ﬁlled in the wear marks and played a protective role during the friction process.

FigureFigure 18. 18. TheThe XPSXPS spectra spectra of (aof) O1s,(a) O1s, (b) Al2p, (b) ( cAl2p,) C1s and (c) (dC1s) N1s and on the(d) wear N1s scar on ofthe the wear aluminum scar of the alumi- numball ball lubricated lubricated using theusing 2 wt.% the JD2000 2 wt.% aqueous JD2000 solution aque asous measured solution using as themeasured UMT tribometer. using the UMT tribometer.4. Discussion Based on the presence of tribo-oxides on the worn surfaces, the essential wear mecha- 4. Discussionnism of this study was oxidative wear [17]. In the oxidative wear mechanism, the metal surfaceBased under on mild the wear presence condition of had tribo-oxides a typical single-layer on the of worn tribo-oxides. surfaces, Under the severe essential wear mechanismwear condition, of this the study multilayer was layers oxidative of tribo-oxides wear [17]. were In sheared the oxidative off from thewear surface mechanism, the during the friction process, leading to large plastic deformation. In this study, the worn metalsurface surface lubricated under by distilledmild wear water condition suffered wide had furrows a typical and severesingle-layer plastic deformation, of tribo-oxides. Under severeresulting wear in thecondition, weak XPS the signals multilayer of Fe2O3 and layers SiO2 ofon tribo-oxides the surface from were steel platessheared and off from the surfacealuminum during plates the [18 friction]. It can beprocess, speculated leading that the to multilayer large plastic tribo-oxides deformation. detached In from this study, the wornthe wornsurface surface lubricated during sliding. by distilled The addition water of thesuffered JD2000 ledwide to the furrows slight scratches and severe and plastic de- few plastic deformation, and the strong XPS signals of oxides and nitrides were detected on formation,the surface. resulting The QCM-D in testthe confirmedweak XPS the signals formation of of Fe viscoelastic2O3 and SiO film2 byon studying the surface the from steel platesadsorption and aluminum behavior of the plates JD2000 [18]. molecules It can on be metal speculated surface. The that measurement the multilayer of water tribo-oxides detachedcontact angle from further the worn confirmed surface that theduring JD2000 slid moleculesing. The can addition achieve stable of the adsorption JD2000 led to the slighton the scratches metal surface and through few plastic active nitrogendeformation, element. and The the MS strong test results XPS show signals that the of oxides and adsorption membrane contains a large number of polymers of different molecular weights. nitrides were detected on the surface. The QCM-D test confirmed the formation of vis- Therefore, combining multiple test results, the lubrication and anti-rust mechanism of the coelasticJD2000 canfilm be obtained.by studying The schematic the adsorption diagram isbehavior shown in Figureof the 19 .JD2000 It can be molecules hypothe- on metal surface.sized that The the measurement molecules of the JD2000of water can becontact adsorbed angle on the further metal surface confirmed by the active that the JD2000 moleculeselement N, can and achieve the long-chain stable molecules adsorption can wellon coverthe metal the surface surface of the through plate under active nitrogen element. The MS test results show that the adsorption membrane contains a large number of polymers of different molecular weights. Therefore, combining multiple test results, the lubrication and anti-rust mechanism of the JD2000 can be obtained. The schematic diagram is shown in Figure 19. It can be hypothesized that the molecules of the JD2000 can be adsorbed on the metal surface by the active element N, and the long-chain molecules can well cover the surface of the plate under the appropriate concentration to form a stable tribofilms and prevent direct contact with rough surfaces. In this situation, the friction state is boundary friction. The shear action appears on the lubricating film to keep the minimum friction coefficient. It also effectively reduces the occurrence of groove and abrasive wear, which can obtain a smoother surface. Therefore, compared with other water-based lubricants, the JD2000 has excellent lubrication performance. Xiangyuan Ye

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Coatings 2021, 11, x FOR PEER REVIEW 19 of 20

the appropriate concentration to form a stable tribofilms and prevent direct contact with rough surfaces. In this situation, the friction state is boundary friction. The shear action appears on the lubricating film to keep the minimum friction coefficient. It also effectively et al. [19] prepared reducesa functionalized the occurrence fluorinated of groove and graphene, abrasive wear, which which cancan obtain only a smootherreduce surface.the wear volume by 64%Therefore, compared compared with withthat other of the water-based distilled lubricants, water. The the JD2000 water has solid excellent carbon lubrica- nanotube prepared bytion Xiaowei performance. Pei Xiangyuan et al. [20] Ye etcan al. [reduce19] prepared the awear functionalized volume fluorinated and COF graphene, by which can only reduce the wear volume by 64% compared with that of the distilled water. 40% and 46%, respectively.The water At solid the carbon same nanotube time, preparedthe dense by Xiaowei protective Pei et al.film [20 ] can reduceresist the the wear corrosion of the surroundingvolume and COFmedia by 40%and and delay 46%, respectively.the corrosion At the reaction. same time, theMost dense of protective the wa- film ter-based additives havecan resist no theobvious corrosion anti-rust of the surrounding performance media and and delay even the corrosionaccelerate reaction. the cor- Most of rosion of metals. the water-based additives have no obvious anti-rust performance and even accelerate the corrosion of metals.

Figure 19. (aFigure) Lubrication 19. (a) Lubrication mechanism; mechanism; (b) corrosion (b) corrosion mechanism; mechanism; and and (c) ( anti-rustc) anti-rust mechanism. mechanism.

5. Conclusions 5. Conclusions In this study, a polyether Jeffamine-triazole derivative which can be used as a water- In this study, a basedpolyether multifunctional Jeffamine-triazole ecofriendly lubricant derivative additive which on different can be material used as surfaces a wa- was ter-based multifunctionalsynthesized, ecofriendly characterized, lubricant and investigated. additive The on following different conclusions material can surfaces be drawn. was synthesized, characterized,1. The preparation and methodinvestigated. is simple, The and thefollowing raw materials conclusions are cheap and can accessible. be drawn. The product can exert the excellent properties of raw materials without environmental pollution. Therefore, it can be used as an ecofriendly water-based additive. 1. The preparation2. methodThe JD2000 is simple, was proved and tothe be raw a multifunctional materials are additive. cheap It hasand excellent accessible. tribolog- The product can exertical propertiesthe excellent compared proper withties other of water-based raw materials lubricants. without The addition environ- of the 2 wt.% JD2000 led to a reduction of 72.7% and 70.2% in friction for steel/steel and mental pollution. Therefore,steel/aluminum it can contacts, be used respectively, as an ecofriendly relative to thewater-based distilled water, additive. and the wear 2. The JD2000 was provedvolume to ofbe the a multifunctional JD2000 reduced by 88.2%additive. for steel/aluminum It has excellent contact. tribological The test also properties comparedimproved with other the anti-rust water-base propertyd lubricants. of the JD2000 The by 75.5%,addition while of some the water-based2 wt.% JD2000 led to a reductionlubricants doof not 72.7% reduce orand even 70.2% enhance in the degreefriction of metalfor corrosion.steel/steel and 3. The adsorption behavior of the JD2000 on metal surface and the formation of vis- steel/aluminum contacts,coelastic respectively, film were confirmed relati byve adsorptionto the distilled behavior water, test and and water the contact wear angle volume of the JD2000tests. reduced Worn surface by 88.2% analysis for further steel/aluminum determined the contact. structure ofThe tribofilms, test also which improved the anti-rustwere property composed ofof nitrogen-containing the JD2000 by substances,75.5%, while metal some oxides, water-based and even polymer lubricants do not reducedeposition. or even It is speculatedenhance thatthethe degree nitrogen ofatoms metal in corrosion. the JD2000 are first adsorbed on the metal surfaces and then form tribofilms. As the third body, the tribofilms improve 3. The adsorption behaviorthe tribological of the JD2000 properties on by metal preventing surface straight and asperity the formation contact from of thevisco- sliding elastic film were confirmedsurfaces. Meanwhile, by adsorption this stable behavior viscoelastic test film canand resist water the corrosioncontact of angle the metal tests. Worn surface fromanalysis the external further environment determined and reduce the structure the corrosion of degree tribofilms, of the metal. which 4. This research can broaden the application of this Jeffamine-triazole derivative in the were composed of nitrogen-containingadditives field and validates substances, its application metal potential oxides, as and a water-based even polymer lubricating deposition. It is speculatedand anti-rust that additive the nitrogen on different atoms metal in surfaces. the JD2000 Concurrently, are first it also adsorbed provides an on the metal surfaceseffective and methodthen form for the trib preparationofilms. andAs application the third of body, an ecofriendly the tribofilms water-soluble improve the tribologicalpolymer-based properties additive. by preventing straight asperity contact from the sliding surfaces. Meanwhile, this stable viscoelastic film can resist the corrosion of the metal from the external environment and reduce the corrosion degree of the metal. 4. This research can broaden the application of this Jeffamine-triazole derivative in the additives field and validates its application potential as a water-based lubricating and anti-rust additive on different metal surfaces. Concurrently, it also provides an effective method for the preparation and application of an ecofriendly water-soluble polymer-based additive.

Author Contributions: Conceptualization, J.W. and W.H.; methodology, J.W. and W.H.; validation, J.W.; formal analysis, J.W.; investigation, J.W.; data curation, J.W.; writing—original draft preparation, J.W.; and writing—review and editing, J.W., W.H., and J.L. All authors have read and agreed to the published version of the manuscript.

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Author Contributions: Conceptualization, J.W. and W.H.; methodology, J.W. and W.H.; validation, J.W.; formal analysis, J.W.; investigation, J.W.; data curation, J.W.; writing—original draft preparation, J.W.; and writing—review and editing, J.W., W.H., and J.L. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the Youth Innovation Promotion Association, Chinese Academy of Sciences (2019288), and Shanghai Pudong New Area Science and Technology De- velopment Fund (PKJ2019-C01). Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Data is contained within the article. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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