United States Patent (19) (11) 4,148,204 Dötzer et al. 45) Apr. 10, 1979

54 PROCESS OF MECHANICALLY SHAPING 2,901,383 8/1959 Lebsanft ...... 134/7 METAL ARTICLES 3,699,013 10/1972 Miyata ...... 204/32 R 75) Inventors: Richard Dötzer; Klaus Stöger, both of FOREIGN PATENT DOCUMENTS Niremberg, Fed. Rep. of Germany 1614690 9/1970 Fed. Rep. of Germany. 73) Assignee: Siemens Aktiengesellschaft, Munich, Primary Examiner-E. M. Combs Fed. Rep. of Germany Attorney, Agent, or Firm-Kenyon & Kenyon, Reilly, (21) Appl. No.: 873,080 Carr & Chapin (22 Filed: Jan. 27, 1978 (57) ABSTRACT Articles made of ferrous, non-ferrous and light metals Related U.S. Application Data and alloys thereof, e.g., aluminum, beryllium, magne 60) Division of Ser. No. 691,707, Jun. 1, 1976, Pat. No. sium, molybdenum, steel, tantalum, titanium, tungsten, 4,101,386, which is a division of Ser. No. 300,906, Oct. vanadium and zinc and their alloys, are pretreated be 26, 1972, Pat. No. 3,969,195, which is a fore coating and surface finishing in an anhydrous, inert, continuation-in-part of Ser. No. 249,276, May 1, 1972, aprotic liquid, and subsequently electroplated with alu abandoned. minum, cadmium, indium or zinc in an aprotic organo metal, electrolyte essentially free of molecular oxygen (30) Foreign Application Priority Data and water and, optionally, additionally finished by an May 7, 1971 DE Fed. Rep. of Germany ...... 212260 odizing, chemical oxidation or diffusion. The pretreat 51) Int. Cl? ...... B21C 23/24; B21C43/00 ment may be by erosion with finely-divided abrasive 52 U.S. C...... 72/39; 29/527.2; particles suspended in such liquid and impinged upon 72/47; C25D/5/44 the surface of the article by hydraulic jetting, or with an 58 Field of Search ...... 29/527.2; 72/39, 42, aprotic liquid by the liquid-drop erosion method. Alter 72/46, 47; 204/14 N, 32 R, 33, 141.5, 145 F natively, the pretreatment may be by electrolytic action in a circuit where the article serves as the anode and is (56) References Cited immersed in an anhydrous, aprotic electrolyte. Articles U.S. PATENT DOCUMENTS so pretreated and electroplated are thereafter more readily surface-finished or mechanically shaped. 2,285,548 6/1942 Wesley ...... 204/34 2,285,549 6/1942 Wesley ...... 204/34 2,873,233 2/1959 Schnable ...... 204/32 R 2 Claims, No Drawings 4,148,204 1. 2 (4.51) specific gravity. Their quickly developing, thin PROCESS OF MECHANCALLY SHAPNG oxide coating (rutile) provides excellent corrosion pro METAL ARTICLES tection in oxidizing media. Although this oxide coating This application is a division of Ser. No. 691,707, filed can be increased in thickness through anodic oxidation, June 1, 1976, U.S. Pat. No. 4,101,386, which in turn is a 5 it has in contrast to the eloxation coating of aluminum division of Ser. No. 300,906, filed Oct. 26, 1972, U.S. (created by anodizing), a deeply violet to bluish-red Pat. No. 3,969,195, which in turn is a continuation-in color and does not possess the honeycomb structure part of Ser. No. 249,279, filed May 1, 1972, abandoned. which is inherent in the colorless eloxation layer of This invention is directed to the art of electroplating aluminum and which provides the superior penetration and surface finishing articles of metals and their alloys, O (advantageous for dyeing or staining) and solidification and more specifically is directed to pretreating the sur (sealing) properties of the eloxation coating. Also, arti face of such an article before electroplating it with cles of titanium do not attain the bright color hue and aluminum, cadmium, indium or zinc, after which it may the good electrical conductivity of aluminum. be further surface-finished, such as by anodizing, or Zinc and zinc alloys also develop oxidic protective mechanically shaped, as by drawing or stamping. 15 layers on the surface, under the effect of atmospheric The coating and surface finishing of articles made of influences, which protect the underlying metal from light metals, particularly beryllium, magnesium, alumi further corrosion. In contrast to aluminum, no methods num, titanium and zinc and their alloys, is often neces are now known for treating zinc that would permit sary, because they are relatively base metals whose reinforcing (thickening) the protective layer by anodic surfaces rapidly develop a fundamentally oxidic coating 20 oxidation or make it possible to build-up oxide layers when exposed to the atmosphere. Such an oxidic coat whose structure permits dyeing or staining. ing usually protects the underlying metal against further Coating by electroplating and surface finishing of the corrosive attacks. However, the surfaces of articles aforementioned light metals in aqueous or protic elec made of such metals properly cannot be finished or trolyte baths is greatly impeded by the very rapid devel coated in aqueous or protic media, due to the character 25 opment of oxide or hydroxide surface coating in air or istics of the metals and oxide coatings. in aqueous hydrous pretreatment and electrolyte media. Attempting to remove the oxidic coating by means of The surface coatings which are always present in aque sand blasting causes the immediate formation of a new ous media prevent or at least greatly complicate the oxide coating in relatively base, oxygen-affinitive met direct electoplating of the basic metal without proper als, due to the ambient air, and this oxide coating makes 30 pretreatment and impair the electro-crystallization, the difficult or even prevents subsequent electroplating. adherence, and the homogeneity of the additional metal This is a major disadvantage, since the excellent me added by electroplating. As a result, electroplating arti chanical properties and the low specific weight of these cles made of light metals, especially of beryllium and metals make their utilization increasingly important in magnesium, from aqueous electrolyte media remains an the construction of air-and space vehicles and automo 35 unsolved problem. Most of all, the electroplating of biles. aluminum and its alloys with other metals still causes The effect of corrosion protection depends very considerble difficulties. largely on the degree of purity of the metal, and, in It also is known that the mechanical forming of mate alloys, on the type of alloying constituents. Generally, rials by drawing, deep-drawing, extruding, pressing, the rate of corrosion will decrease as the degree of 40 embossing, stamping, squeezing, rolling, etc., can be purity of the metal increases. Alloying constituents facilitated and improved through the use of auxiliary should not be selected only with respect to their favor substances such as drawing soaps, pastes, fats, oils, lu able influence upon the corrosion behavior of the base bricants and the like, and that considerable advantages metal but, most of all, with respect to the improvement as to production and economy can be obtained through they impart to the mechanical, processing and casting 45 the choice of suitable auxiliary agents for the material characteristics of the base metal. Iron that is kept ex and the tools. tremely pure through zone pulling and suspension melt Coating of the material to be formed with metal can ing will virtually not corrode in moist air. be of advantage in the forming process. According to "Electron metal,' which is an alloy with 90% and the discussion in the paper "Technology of the Hard more of magnesium and, depending on usage, including 50 Superconductors' by H. Hillman in Zeitschrift fuer varying amounts of aluminum, zinc, manganese, copper Metallkunde, Vol. 60, No. 3, particularly at pp. 162 and and silicon, can be processed very easily by machining, 164 (1969), for instance, wire material coated with cop but quickly becomes subject to atmospheric corrosion. per shows better than 99% cold forming of a niobium The die-casting aluminum alloys which are particularly titanium alloy, which in itself is very hard and almost desirable for manufacturing, such as the alloys conven 55 brittle. tionally denominated DG AlSil0(Cu), DG AlSil2 and It has now been found that the shaping of articles DG AlSi6Cu3, cannot be finished by anodizing or, if made of ferrous, non-ferrous heavy- or light-metals can anodized, will result in an unsatisfactory quality and be facilitated considerably if the substrate metal has have an unsightly gray color. been electroplated with high-purity aluminum, zinc, Beryllium and beryllium alloys which are preferred 60 cadmium or indium. The formability of the metal is modern construction materials due to their excellent considerably improved, and at the same time its surface strength at a very low (1.86) specific weight lack a is protected and upgraded with respect to the properties dense, adhering and non-toxic surface-protection film to which are of technical interest. Shaped articles which protect then against severe corrosive attack. have been electroplated according to the invention and Titanium and titanium alloys find increasingly greater 65 which have been forced by drawing, embossing, press use in air-and space vehicles, as well as in machinery ing and stamping, as well as by sqeezing, rolling and by construction and in the chemical industry, because of explosion methods, possess the mechanically and tech their excellent mechanical properties at a relatively low nologically advantageous properties of the substrate 4,148,204 3 4. metal, such as high strength, magnetism and high elec reversal. The article is protected from exposure to mois tric conductivity, together with the particularly useful ture and oxidizing conditions after being pretreated and surface properties of the named electroplating metals, until it has been electroplated. After electroplating, the such as for instance, corrosion protection, ultrasonic article may be provided with an eloxal coating, option weldability and solderability, anodic and chemical oxi ally later stained with dye, by anodizing. Also, it may be dation, which can be combined with further possibilities surface-finished by chemical oxidation or metal diffu for surface finishing. In the case of rolling, squeezing sion techniques. and explosion forming processes, the electroplated coat (As used herein to refer to the pieces of metal being ings fulfill a function which saves and protects the sub treated in accordance, with this invention, "article' strate metal and ideally transmits forces due to work 10 refers broadly to metal (including alloys) in various hardening. stages of fabrication into an article of manufacture, and Metals, particularly ferrous and heavy metals, pro may be in the form of sheets, bars, slabs, strips, mold vided with an electroplated coating in accordance with ings, die castings, stampings, extrusions, and the like, the invention as an auxiliary forming agent can be de and assemblages of two or more pieces joined together.) formed to a greater extent than heretofore. The draw 15 It has been discovered that the surface of articles of ing properties, for instance, can be improved. Articles metals and their alloys can be electroplated with an with thinner walls can be produced, and it becomes adhesive, homogeneous and dense coating, if the sur possible to work metals which heretofore could be face of the article is first pretreated in an anhydrous, shaped only with difficulty or not at all. Because of the inert aprotic liquid and subsequently electroplated in an unusually high ductility of the above-mentioned elec 20 aprotic, organo-metal electrolyte which is substantially troplated metals, the problem of cutting and stamping devoid of water and molecular oxygen, and, optionally, edges becomes manageable, with proper design of the further surface-finished. tools, through coating and compression welding. The pretreatment according to the present invention Accordingly, it is an object of this invention to fur in aprotic organo-metal electrolyte media, free of oxy nish a process by which light metals and alloys of them 25 gen and water, produces bright light-metal surfaces, may be first pretreated to remove surface layers of free of surface films, which do not corrode, thereby oxides and/or scale and thereafter electroplated with a allowing an ideal, immediate deposition of the protec thin coating of aluminum, by which process the light tive metal upon the surface of the light metal. metal article is provided with a tightly adherent, uni When necessary, the surface treatment of the articles form layer of highly pure aluminum. 30 may be effected under the exclusion of air in an atmo Another object is to furnish a process by which light sphere of inert gas. This provides a bright surface with metals, especially beryllium, magnesium, titanium and out surface film for these metals which would otherwise zinc, may be coated with a thin coating of aluminum react in aqueous or protic media or when exposed to air, and thereafter anodized to furnish an eloxal coating on and develop oxide-hydroxide or salt-like surface films the surface thereof, 35 which would prevent further electroplating, or at least A further object it to furnish a process by which interfere therewith, and reduce or impair the adhesive metals, particularly ferrous and non-ferrous heavy met ness of the protective metal being plated onto the sur als, may be coated with a thin coating of aluminum, face. - cadmium, indium or zinc which facilitates the subse The above-mentioned electrolytic metals, which are quent mechanical shaping of the coated metal. 40 relatively soft by nature, when electroplated on the Broadly stated, in a process of electroplating with surface-treated substrate metals under oxygen- and wa aluminum, cadmium, indium or zinc, an article made of ter-free conditions are strongly adherent, with a purity a ferrous or a non-ferrous heavy- or light-metal or an of better than 99.99%. The strong bonding to the base alloy thereof, the invention is the improvement of pre material, which is necessary if the electroplated metal is treating the surface of such an article with an anhy 45 to serve as an auxiliary forming agent, is thereby as drous, aprotic liquid for the purpose of removing scale sured. Functional coatings such as, for instance, copper and exposing bright metal, and subsequently electro or nickel, may already have been applied to the sub plating the article with aluminum, cadmium, indium or strate metal to facilitate solderability. The auxiliary zinc in an aprotic electroplating electrolyte. The pre layer or electrodeposited-metal layer, respectively, can treatment is advantageously done by eroding the sur 50 also be joined to the substrate even more intimately face of said article with finely-divided abrasive particles prior to forming by a heat treatment, by virtue of diffu suspended in such anhydrous aprotic liquid, which may sion processes. Because of the considerably higher pu be, for example, a normally-liquid hydrocarbon, a halo rity of the metals electroplated on the surface of the genated hydrocarbon, a perhalogenated hydrocarbon substrate from the aprotic, oxygen- and water-free, or a silicone oil, or an appropriate mixture of them. The 55 organometallic electrolytic media, particularly advanta liquid may be impinged against the surface of the metal geous surface properties are obtained, and at the same by hydraulic jetting under high pressure, or by the time a coating is created which is valuable from the liquid drop impact erosion technique. Alternatively, the viewpoint of possible uses of the coated article. surface pretreating may be done bypassing an electrical The process may be applied to light metals, such as current through the article electrically connected to 60 aluminum, beryllium, magnesium and titanium, and to operate as the anode of the circuit, while it is immersed ferrous and non-ferrous heavy metals such as, for in in an aprotic electrolyte essentially devoid of water and stance, titanium, zirconium, hafnium, vanadium, nio molecular oxygen. Thereafter, the article is electro bium, tantalum, molybdenum, tungsten, rhenium, or in plated in an aprotic electroplating electrolyte. The elec general, materials which exhibit sufficient plasticity to troplating electrolyte optionally may be one having the 65 be worked by one of the mechanical forming processes general formula MXAlR'R''R+(m) solvent, as de mentioned above and which have sufficient electrical scribed hereinafter. The electroplating may be con conductivity or can react at their surface so that they ducted employing a pulsed current and cyclical polarity can be cathodically coated in aprotic, oxygen- and hy 4,148,204 5 6 drogen-free electrolytic media. Even though the advan the need of aqueous etching and rinsing baths and there tage of the method according to the invention is partic fore also eliminates waste water disposal problems. ularly great in connection with aluminum-plated fer The surface pretreatment according to the invention rous materials, the advantages of better formability and may also be effected through liquid-drop impact ero surface finish also exist with a coating of electroplated sion, with inert, anhydrous, aprotic liquids. Such a cadmium, zinc and indium. method is described, for example, in German Pat. No. In the following text, electroplating of aluminum 1,614,690. This embodiment of surface treatment is par onto light metals will be described illustratively. ticularly suitable for strip and sheet material for contin In a preferred embodiment of the present invention, uous operation and represents the method that is most the pretreatment is effected by hydraulic jets having 10 suitable ("best matched') to the material being treated. abrasive particles suspended in oil or other inert liquids, It is characterized by the following process steps: such as, e.g., paraffin oils, high-boiling hydrocarbons, 1. manufacturing sheets or strips of the metal to be chlorinated hydrocarbons, silicone oils, and the like. A treated, optionally wound on a reel or drum for specific system employs a light oil and corundum pow feeding into the process; der having particle sizes between about 50 and 200 15 2. pretreating the metal by liquid-drop impact erosion microns, with jet pressures between about 1 and 10 (in which the drops of liquid fall under the influ atmospheres gauge, preferably 3 to 7 atm. As a propul ence of gravity) with benzene or toluene, option sion means, the oil itself can be circulated or accelerated ally after preheating the metal; and with compressed air or an inert gas, such as nitrogen. 3. immersing the metal into the electrolyte bath em The abrasive particles may be corundum, silicon car ployed for electroplating. bide, glass beads, and the like. for safety reasons, the liquid-drop impact erosion is The hydrophobic liquid film which surrounds the conducted in an atmosphere of gaseous nitrogen or abrasive particles displaces air and moisture during its perhalogenated hydrocarbons. impingement upon the metal surface to be cleaned, so . The aforementioned advantages also apply to this that the abrasive particles break through the oxide sur 25 procedure. face layer within the liquid film and expose the bare A third suitable surface pretreating method is the metal surface, which is being protected by the liquid anodic removal of a thin surface layer of the light-metal film against the access of air and moisture. article in an aprotic organo-aluminum electrolyte me The pretreatment according to the method of the dium, more particularly, in electrolytes containing alu present invention is a relatively gentle mechanical treat 30 minum ethyl and/or aluminum methyl. The ethyl or ment of the surface of the article. The surface removal methyl radicals which are generated at the anode dur takes place within a range of only a few tenths to a few ing the passage of current, dissolves the light metals into microns of layer thickness. Thicker oxide and scale liquid metal alkyls (MR): layers can be removed beforehand by sand blasting or by chemical pretreatment. This is not required, how 35 ever, for newly processed greased or oiled articles. The oxide layers which also develop at room temperature on dry surfaces of light metals can also be directly re moved by hydraulic jets with abrasive particles sus 40 pended in oil. It is a particular technical advantage of this invention that greased articles can be immediately Ti+4R-TiR, subjected to the surface pretreatment described herein. The surface-finishing method of our invention, which While articles made of beryllium or aluminum may is suitable for all materials, has the following processing 45 also be anodically dissolved in aluminizing electrolyte steps, when conducted by means of hydraulic jets: media containing halides, particularly hydro-fluorides, 1. mechanical fabrication of the article; this cannot be done with articles made of magnesium or 2. pretreating the surface of the article with a hydrau zinc, because of the formation of insulating surface lic jet of an abrasive suspended in an aprotic liquid, layers of a metal halide, especially MgF2 or Zn2. Elec preferably oil; 50 trolytes suitable for effecting anodic pretreatment of 3. removing an oily or greasy film, if any be present, any of the light metals referred to herein are the tetra from the article by immersion into a suitable sol alkyl alanate-complexes which are free of halide ions, vent, such as perchloro-ethylene (sometimes de nominated PER); 4. thereafter completing the de-greasing by PER 55 vapor de-greasing; The mixed sodium potassium salts of the tetraethylala 5. promptly immersing or rinsing the article in tolu nate, which melts at 70 C, is particularly advanta ene, optionally with ultra-sonic vibration; and; geous. The sodium salt first melts at 128 C. Light metal 6. promptly immersing the article into the electrolyte articles which are anodically treated in these molten bath employed for electroplating. electrolytes and thereby pretreated with respect to their By routine experimentation varying the type and size surface, may be immersed under inert gas into the elec of the abrasive particles, the viscosity of the aprotic troplating cell, still wet with the pretreating electrolyte, liquid, and the jet pressure, suitable operating condi and electroplated with aluminum by means of cathodic tions can be obtained for each metal and each surface action. characteristic, and bare metal surfaces, free of surface 65 With articles made of beryllium and aluminum, the filing, can be obtained. anodic surface pretreatment can be carried out directly It is noteworthy that this embodiment of pretreating surfaces requires few process steps and works without in the electroplating cell and the bare metal surface can 4,148,204 7 8 be electroplated with aluminum by means of polarity R" may be the same as R, but may also be an hydride reversal. This particularly favorable embodiment of the (H-) radical or an halide (F, Cl) or other monova surface pretreatment method in an aprotic electrolyte lent negative ion (e.g., CN, N3); R" is selected from medium, free of water and oxygen, comprises the foll the same class of radicals as is R' and on any specific lowing steps: molecule of the complex, may be the same as or differ 1. vapor-degreasing with PER the article to be ent from R', and m (mols) may be in the range of 0-5. treated and draining excess liquid from its surface; Suitable solvents are, e.g., aromatic hydrocarbons, par 2. washing, or rinsing, the article with toluene, op ticularly toluene and xylene, and ethers, preferably tionally with ultra-sonic vibration; higher-boiling ethers, such as tetrahydrofuran, dipro 3. immersing the article, wet with toluene, into the 10 pyl-dibutyl ether, dioxane, etc. Electrolytes of this type electroplating bath, electrically connecting the are disclosed, for instance, in German Pat. Nos. article as the anode of the circuit, and anodically 1,200,817 and 1,236,208. The organo-aluminum electro charging it for a time, about 15 min, sufficient to lytes may be used alone, or in a mixture. In order to remove the surface film or scale, optionally with increase their conductivity, they may be diluted with concurrent movement (sometimes referred to in 15 the electroplating art as agitation) of the article; aromatic hydrocarbons, e.g., toluene. and, The upper limit of the bath temperature during elec 4. reversing polarity and electroplating aluminum troplating is determined by the thermal stability of the onto the surface of the article. electrolyte and the boiling point of the solvent if any is used. It is above 130' C. When articles comprising magnesium, zinc or tita 20 nium are treated, process steps 1 and 2 are first con Metal being coated with aluminum acquires an adhe ducted. Thereafter, the article, wet with toluene, is sive coating which is very pure and therefore bright like immersed into the molten pretreatment electrolyte bath silver, exceptionally ductile and corrosion-resistant. of 80 to 100° C. bath temperature, consisting, e.g., of a This coating is produced in the absence of oxygen and 1:1 mixture of NaAl(C2H5)4) and KAl(C2H5)4), and is moisture as well as corrosive media, and thus does not anodically stressed for a short period in order to loosen 25 contain interfering intermediate layers. The thickness of and remove the surface film and scale. Subsequently, the electroplated coating is normally in the range of the article is immersed, wet with pretreatment electro about 10 to 30 microns. Due to these advantageous lyte, directly into the aluminizing bath, under inert gas characteristics, it is called "galvanoaluminum.” Because (N2), and the cathodic aluminizing electroplating pro of its high degree of purity of at least 99.99% aluminum, cess is conducted, accompanied by electrode agitation. 30 this galvano-aluminum always provides, regardless of Besides these surface pretreatment methods, one can the peculiarities of the base material of the molded bod apply methods which produce bare surfaces, free of ies and structural components, a high degree of corro surface films, in other ways and which permit a mois sion protection and a silver-bright, very decorative ture-free immersion of the article into the aluminizing appearance; hence it represents a true surface finish. bath, such as structural components freshly machined 35 This applies equally for beryllium, magnesium, titanium under oil, from solid material, that can be placed into and zinc as well as for aluminum articles. In addition, the aluminizing bath, following PER degreasing and galvano-aluminum layers have very good electrical washing in toluene. surface conductivity, superior ultrasonic weldability According to the invention, the aluminization by due to their high ductility (20 kg of force/mm2 HV; electroplating can be carried out with aprotic organo 40 equal to 200 Newton/mm2HV), and high reflectivity aluminum electrolyte media, free of molecular oxygen after burnishing or polishing. The high ductility of the and water, preferably with electrolytes containing an galvano-aluminum lends the structural components of aluminum alkyl. The use of special current and electrol high strength, hard materials, particularly beryllium, ysis conditions, particularly pulsed current with polar magnesium and titanium alloys, a good sliding surface ity reversal cycles, may have a favorable influence upon 45 the type of deposition of the electro-deposited alumi and a metal-to-metal sealability with appropriate num. The particular type of electro-crystallinity pro contact pressure. duces a dull, glare-free surface. Normally, the deposi Furthermore, the components electroplated with tion current density is in the range of 10-20 mA/cm2. aluminum have excellent properties for anodizing. This Good electro-deposition can be obtained even up to 60 50 expands the possibilities for surface finishing the gal mA/cm2. At higher current densities, an intensive vano-aluminum-coated light-metal articles to a particu movement of the cathode or of the electrolyte is prefer larly large degree. In addition to the corrosion protec able, particularly for the disipation of the Joulean heat tion resulting from the silver-bright but relatively soft which is released. galvano-aluminum plating there is also the corrosion 55 protection by the crystal-clear, transparent and wear On principle, all organoaluminum electroplating elec resistant galvano-aluminum eloxation layer which is trolytes which correspond to the following general surprisingly hard (over 4000N/mm2HV) and which formula are suitable for carrying out the method ac protects the surfaces of the article against mechanical cording to the present invention: damage. The protective layers which are produced by anodic exposure of the galvano-aluminum coating in the MX.nAllR'R''R--m solvent eloxation (anodizing) baths (which are known perse) in where M can be Na+, K+, Rb, Csor a quanternary almost any desired layer thickness, owe their particular onium ion with N, P, As or Sb as the central atom or a characteristics to the high purity of the galvano tertiary oniom ion with S, Se or Te as the central atom; aluminum. These characteristics are exceptionally crys X is preferably F- or Cl- but also Br and I, CN, 65 tal-clear transparency, high homogeneity and hardness N3 or (SO4)2; n is greater than unity, preferably 2 to of the eloxal layer, good insulating properties and heat 3; and R is always an organyl radical, preferably an conductivity, the clear-color dye-ability and stainability alkyl radical; more particularly ethyl or methyl radical; of the eloxal layers produced in GS baths, and very 4,148,204 10 good hardening (or sealing) characteristics of the gal the fabrication process mentioned above as a soft, duc vano-aluminum eloxal layers from GS and GX eloxa tile, adherent and gently force-transmitting auxiliary tion baths. agent, which makes other auxiliary substances of the In accordance with a preferred embodiment of the conventional kind unnecesprotection for the normally invention, the aluminum coated articles are anodized as less noble substrate metal, imparts higher electric con an after-treatment. When the above-indicated, specific ductivity, excellent weldability and solder-ability and requirements for the current and the electrolyte for the presents a metallic, bright and possibly brilliant decora deposition of the aluminum are adhered to, a dense and tive appearance. perfect anodic oxidation is obtained with the methods Depending on the peculiarity of the electroplated commonly used in industry. The resulting GS eloxal 10 metal applied, the following surface properties or sur layers can subsequently be dyed and solidified (sealed). face finishing possibilities can be listed in addition to the If dyeing is not desired, the solidification (sealing) is properties which are effective for forming, namely, carried out with boiling water above 95 C., or with electroplated aluminum, which is especially ductile superheated steam. from room temperature to 660 C.; The crystal-clear eloxal layers obtained when the 15 electroplated zinc, which is especially ductile from article is pretreated and electroplated according to the 80' to 160 C.; method of the present invention are characterized, par electroplated cadmium, which is especially ductile ticularly, by extreme hardness (400 kg/mm2 HV; 4000 from room temperature to 321 C.; Newton/mm2HV) and wear-resistance. They can be electroplated indium, which is especially ductile from dyed with color-clearness and be printed on. They also 20 room temperature to 156' C.; have good thermal conductivity with a high insulation where approximately the following order applies re resistance and a high corrosion-protection capability garding softness of the electroplated metals: and can readily be polished by mechanical means. In some cases, when corrosion protection is desired n>Cd Al-Zn, irrespective of the decorative surface appearance, yel 25 and the bondability to the substrate metal in the forming lowish or greenish protective layers can be produced in process (in the manner of compression or friction weld the galvano-aluminum coating by conventional chemi ing) increases from zinc to indium to cadmium to alumi cal oxidation methods, such as, for instance, the chromatizing method. In other instances, for example Due to its high purity of over 99.99%, electroplated with titanium and titanium alloys, a particularly hard aluminum exhibits a strong corrosion protection effect, titanium-aluminide layer can be produced by diffusing which can be enhanced further by anodic oxidation to in the electro-deposited aluminum layer. form eloxal layers. These can be sealed, are insulating, Some of the special characteristics of aluminum can be dyed and printed, and are extremely hard and which are responsible for its wide technical application abrasion resistant. The electroplated aluminum layer as can thus be applied on surfaces of other metal articles. 35 well as the electroplated aluminum eloxal layer makes a For example, the dyeing properties (inherent only to good adhesion base for paints and adhesives. It has a aluminum) of the layers which can be produced by silver-bright appearance, can be polished and burnished anodizing in GS baths, can be applied to other metals and has very good thermal and electrical properties, and to the gray or black eloxalized aluminum alloys. excellent ultrasonic weldability and solderability. Good The surface oxide-layers of beryllium, magnesium, tita bonding possibilities by friction and compression weld nium and zinc articles cannot be dyed. ing exist. It is highly suited for subsequent diffusion A particular advantage of the present invention lies in processes (aluminide formation). the fact that light metals and alloys, particularly beryl Electroplated zinc has a metallic, bright appearance lium and magnesium and high-alloy aluminum which and also exhibits a good corrosion protection effect, are particularly suitable for mold-casting, extrusion or 45 which can be enhanced further by chemical oxidation, die casting procedures because of their high strength for instance, by chromatizing. The zinc layer constitutes and good machinability, or their excellent workability, a good adhesion base for paints and lacquers, and is well can be provided with the excellent surface characteris suited for soldering. tics of high-purity aluminum, the galvano-aluminum Electroplated cadmium is distinguished particularly coating. A coating according to our invention provides by a good corrosion protection effect for ferrous mate not only durable corrosion protection but very often rials. It forms a useful adhesion base for paints and lac makes possible the application of these metals in tech quers and is highly suited for soldering. It is also suitable nology. Thus, for example, magnesium and magnesium for ultrasonic welding. As it is suited as a base for chro alloys could not heretofore be electroplated. mium plating, protection of the rather soft cadmium A further, very particular advantage of the invention 55 against mechanical damage being best brought about by resides in the fact that the electroplated metals exhibit a chromium plating, and at the same time, excellent pro very effective sliding and lubricating effect. Electro tection against corrosion is obtained. plated aluminum has a Vickers hardness of less than 200 Electroplating with indium is particularly well suited N/mm2HV and is therefore more than three times more for friction and compression welding. ductile (or softer) than gold. Contaminating lubricants It should also be emphasized that the galvano and forming additives becomes unnecessary. If materi aluminum deposition may be done in the complete ab als electroplated according to the invention with alumi sence of hydrogen. This factor is of particular impor num, zinc, cadmium or indium are used, the service life tance among the light metal metals being discussed of the tools for the drawing, pressing, embossing and here; e.g., titanium absorbs into its metal lattice hydro stamping operations is considerably increased, by up to 65 gen present in statu nascendi, thus changing its mechan 50%. ical properties in an adverse manner. The hydrogen The coating of electroplated metal therefore not only embrittlement and stress corrosion induced thereby makes possible and facilitates the mechanical forming in cannot occur in electroplated materials; this is an ex 4,148,204 11 12 tremely important advantage of the galvano-aluminum both sides with electrodeposited aluminum, zinc, cad coating. The metal deposits occurring from aqueous mium or indium. electroplating baths are almost always accompanied by Aluminum has the greatest importance among the a rather strong hydrogen evolution, which at the same electroplated metals mentioned because of its special time reduces the cathode efficiency. The galvano 5 properties and its favorable melting point of 660 C., aluminum deposition takes place without generation of and, not least, because of its low price. For this reason, hydrogen with a cathode efficiency of almost 100% of the advantages and possible applications for mechanical theoretical. forming processes and surface finishing attending the The method of the invention can be used for coating electrodeposited aluminum coating will be illustrated in or for surface finishing various molded bodies of base, 10 the following examples; the same or similar procedures oxygen-affinitive metals. Surface protection with a de are also possible with the other electroplated metals and sirable decorative appearance may be obtained; this is lead to analogous results. important particularly for components used in den The invention will be described in greater detail in tistry, electronics, in the automobile industry, as well as the following Examples: in air and space vehicles. Due to its high ductility, the 15 galvano-aluminum plating can also be used as a sliding EXAMPLE 1. and lubricating film. Furthermore, surface brightness Electro-Aluminizing of Beryllium Discs (luster) can be provided by mechanical means, as for 2 mm-thick beryllium discs of 40 mm diameter are example by buffing, or also by barrel polishing. The 20 arranged in a cathode frame consisting of titanium, fixed shiny surfaces can be protected against mechanical at the lateral edge with small dovetail pins, and con damage by subsequent anodizing. A further advantage tacted. Following PER vapor-degreasing and drying, of the high ductility of the aluminum coating is also the arrangement is placed, wetted with toluene, into the found in the bonding technique of ultrasonic welding. aluminumizing electrolyte comprising trimethyl-ben The galvano-aluminum eloxation layers make it possible 25 zylammonium-hexaethylmonochlorodialanate with an to finish the surface of handles, front panels, substrates excess of 0.2 mol of Al-triethyl, in toluene (1:3) and is and die castings. Moreover, the galvano-aluminum anodically plated at 80 C. for 15 min. with intensive eloxation layer forms an ideally adherable base on the agitation of the electrolyte media. Then the polarity is surface of the light metal articles for painting, plastic reversed and, at a current density of 11 mA/cm2, ac coating, cementing and impregnating. 30 companied by further electrolyte agitation, a galvano For continuously operating aluminizing installations, aluminum layer of about 15 micron thickness is depos for instance, for wire and strip run-through installations, ited in 90 min. The discs are removed from the aluminiz the procedures of electropolishing, known perse, (there ing cell, the adhering electrolyte is rinsed off the discs are available electrolytes for ferrous materials, non-fer with toluene, which are then briefly dipped into TRI rous metals and aluminum materials, and others) with 35 NORM 'Al' and washed in water, and thereafter dried subsequent intensive washing, water displacement (by with acetone. The galvano-aluminum coating has a means of dewatering fluids) and wetting with toluene bright fine-crystalline appearance. can also be used to advantage for producing and retain The beryllium material is coated with tightly adher ing a pure, bare surface which is also protected against ing, galvano-aluminum. The galvano-aluminum layer renewed oxidation. Particularly inferrous materials, the may be anodized, and further surface refining such as so-called surface cleaning with copper flash (less than dyeing, marking, printing, lettering, cementing, etc. 0.5 micron of copper layer) in an aqueous system, with washing and water displacement, may be employed in may be carried out. addition to the methods described above. For the or EXAMPLE 2 ganophilic beryllium, magnesium, zinc and aluminum 45 Electro-Aluminizing, Anodizing and Dyeing of materials, the surface pretreatment by anodic loading in aprotic, oxygen- and water-free organometallic, prefer Beryllium Blocks ably organo-aluminum electrolytic media, has been In a titanium cathode frame, four beryllium blocks found to be particularly suited. (6x6X 16 mm) are fixed above their square end faces The layer thickness to be chosen for the electroplated 50 with two titanium contact tips and hydraulically sur aluminum depends primarily on the intended extent of face-treated with 70 micron fine electro-corundum par deforming of the substrate metal, and secondarily on the ticles suspended in a 1:1 mixture of paraffin oil-silicone desired thickness of the eloxal layer. Also the harness or oil at a jet pressure of 6 atm. Subsequently, they are ductility, respectively, of the substrate and the speed of washed at once in a PER immersion bath, degreased in forming have an influence on the required or optimum 55 a PER vapor bath and rinsed in toluene. Wet with tolu layer thickness of the electroplated coating. ene, the beryllium blocks are lowered under dry nitro In case the electroplated coating is made; only as the gen gas into the aluminizing cell, the electrolyte of auxiliary forming agent and its presence on the surface which is NaI(C2H5)3AlFAl(C2H5)3).3.4C6H5CH3. At of the formed part is undesirable, the coating can be an electrolyte bath temperature of 95-100° C., electro removed again by mechanical, chemical or electro deposition of aluminum takes place under mechanical chemical means. cathode agitation, with a current density of about 10 By the method according to the invention, drawn, mA/cm2. After 3 hours, with a polarity reversal cycle pressed, embossed and stamped parts and parts pro of 4:1, a galvano-aluminum layer of about 30 microns duced by squeezing, rolling or explosion methods, thickness is plated on the surface of the blocks. It is which heretofore have been made preferably of light 65 highly adherent and homogeneous. The adhering elec and non-ferrous metal materials such as, for instance, trolyte is removed from the blocks by washing in tolu brass or copper, may also be made of ferrous materials. ene, blow-drying and brief immersion into TRI In particular, sections of steel strip can be coated on NORM'Al'. 4,148,204 13 14 With the same arrangement of the beryllium blocks in atmosphere to surface pre-treatment. The electrolyte the titanium frame, the anodizing process is carried out bath was molten (90-100° C) 50% NaAl(C2H5)4 and immediately thereafter at 18" C. in a GS (direct-current, 50% KAl(C2H5)4). With the electrolyte circulated by sulphuric acid) anodizing bath. Within 35 minutes, a stirring, the surface of the electron metal bars is anodi colorless, crystal-clear galvano-Al-eloxation layer of 5 cally pre-treated for 15 min. at a current density of 18 approximately 12 microns thickness grows on the sur mA/cm2, and a surface film about 2 microns thick of face. magnesium is removed, together with the oxide surface Prior to solidification of the eloxal layer in boiling layer. A nickel screen serves as the cathode. With a deionized water for about 30 minutes, a coated block is favorable arrangement of the pre-treatment bath, imme dyed in a staining solution of 5 g/liter of a dye known as O Aluminum-True-Red B3LW (available from SANDOZ diately adjacent to the aluminizing bath, the frame and AG, Basel) for 10 min. at room temperature. While the workpieces, still wet with electrolyte, can be directly uncoated beryllium blocks have a blue-grey surface lowered, under protective nitrogen gas, into the alumi color, the unstained anodized blocks, coated with a nizing cell. Otherwise, the frame and the now-metalli galvanoaluminum-eloxation layer, have a matte silver 15 cally-bare electron metal parts are rinsed with toluene bright hue. and the toluene-wetted parts are transferred to the alu In the same manner which applies to pure beryllium, minizing bath. molded articles of beryllium alloys, particularly high In an 80 C. plating electrolyte bath of NaC2H5)3Al percentage beryllium-aluminum alloys with 48 to 52% Fal(C2H5)3)4.0C6H5CH3, the parts are coated, over a beryllium content, can be coated and stained or dyed, period of 2.5 hours, with a galvano-Al layer about 25 printed-on or lettered. Suitable dyes are, for example, 20 microns thick. The process is conducted at a cathode the Aluprint dyes available from SANDOZAG, Basel. agitation rate of 6 cm/sec and 12 mA/cm2 current den sity by means of a pulse current (5:1) and 25 Hz. After EXAMPLE 3 spraying with toluene, rinsing with hot water and dip Electro-Aluminum-coating Of Cylinders Of 25 ping for a few seconds in TRINORM "Al', the alumi Magnesium Alloy nized electron bars are given an anodizing treatment in Two cylindrical pieces of 70 mm diameter and 100 a GS bath at 18 C. for 20 min. The resulting eloxation mm length consisting of magnesium alloy are attached layer, fully transparent and about 8 microns thick, is in a rotating holder of Tirods, and their surfaces treated dyed for 5 min. in a 60° C. SANDOZ staining bath with by means of pressure jets with 80 micron glass beads in 30 Al-True Gold L(2 g/l) to a gold color and is solidified PER at a jet pressure of 6 atm. After spraying with hot in boiling water for 30 min. PER and, finally, PER vapor, the still-hot parts, to gether with the rotating holder, are immediately low EXAMPLE 5 ered into the 100° C. aluminizing bath and aluminized Electro-Aluminizing, Anodizing, Printing And Dyeing between two Alanode plates (space about 15 cm) with a 35 Of Die-Cast Zinc Articles cathode movement rate of 10 cm/sec and rotation of the parts. The current source is a pulse generator which, at Toy cars (approx. 60X28X20 mm) of die-cast zinc a cathode/anode polarity reversal cycle of 4:1 (rectified alloy, e.g., DG ZnAl4 or DG ZnA14Cul, are disposed value of cathode current, 12A; of the anode current, 3 at a distance of 20 mm in a frame with two titanium (A) and 50 Hz. deposition frequency, at about hi5 V point-holders and are surface-treated by means of pres deposition voltage (amplitude height), applies an aver sure jets with electro-corundum (70 microns) in viscous age current density of about 15 mA/cm2 to the objects paraffin oil at a jet pressure of 5 atm. After washing in to be aluminized. In 2 hours of plating time, a silver PER, degreasing in PER vapor and rinsing in toluene, bright, pore-free and tightly adhering galvano the toluene-wetted frame with the cars is transferred aluminum coating about 30 microns thick is obtained on 45 under N2 gas into the aluminizing electrolyte. With the cylinder surface. The cathode frame, withdrawn in cathode agitation of 10 cm/sec, the die-cast zinc toy a dry nitrogen atmosphere from the aluminizing bath, cars are coated on their outer surfaces under the current together with the coated magnesium cylinders, is conditions stated in Example 3, resulting in an approxi sprayed with toluene and thus cleansed of the adhering mately 30 micron thick plated galvano-Al layer. electrolyte. In the same manner, any desired magnesium 50 One half of the number of Zn die-cast parts are pol materials which are frequently used because they are ished by means or barrel polishing with steel balls of 8 easy to work by casting, can be provided with an alumi mm diameter, in a rotating polyethylene barrel and, num layer, which further increases the usefulness of subsequently, anodized in a CS bath of 15 C.; the ether these light metals. half is directly subjected to anodizing without polish 55 ling. EXAMPLE 4 For carrying out the anodizing treatment, the interior Electro-Aluminizing, Anodizing and Staining Of Bars surfaces of the toy cars are coated with a masking paint Of Electron Metal, Containing 90% Or More Of that resists sulfuric acid and, thereafter, the outer area is Magnesium and Minor Amounts Of Aluminum, Zinc, coated with an elonation layer of 15 to 20 micron thick Manganese, Copper and Silicon 60 ness. The wellwashed elonation surfaces are then In a 300X500 mm titanium cathode frame of an 80 marked and printed with Alu-print "Black” color-paste liter aluminizing cell, 8 pieces of electron metal bars of (SANDOZAG, Basel) and thereafter stained for 5 min. 135X26X 16 mm, with longitudinal slots of appr. 1 mm at room temperature is a SANDOZ color bath of Al width and 0.5 mm depth, are fixed in two rows by Blue LIN (3.5 g/l) and subsequently solidified in boiling means of titanium point-contacts over the cross-sec 65 water of pH 5.5 for 30 min. tional area. After intensive PER vapor degreasing and In this manner, shiny as well as glare-free mat, wear rinsing with toluene in an ultrasonic bath, the toluene resistant, printed and stained galvano-Aleloxation layer moistened parts are subjected in a protective nitrogen surfaces are obtained. 4,148,204 15 16 triethyl, dissolved in an equal volume of toluene, at a EXAMPLE 6 cathode movement of 15 cm/sec and an aluminum Electro-Aluminizing And Anodizing Treatment of anode spacing of 5 cm with a current density of 10 Hollow Cylinders Of Malleable Aluminum Alloys mA/cm2. With the aid of threaded titanium supporting mem 5 bers, 5 columns each comprising 8 hollow cylinders (20 EXAMPLE 8 mm outside diameter, 54 mm long, 1.5 mm thick) of an Electro-Aluminizing And Masked Anodizing alumina alloy (AIZnCu 1.5 F53) are fixed upon one Treatment And Dyeing Of Aluminum Sheets another and simultaneously contacted in the frame of an 80-liter aluminum electroplating cell. In the pressure-jet O Six sheets (100x50X2 mm) of 99.5% pure aluminum, apparatus, the parts are surface-treated while being are fixed in an insulated titanium frame structure in two rotated with 6 atm. jet of micron corundum powder in rows above each other by means of Tipoint contacts, paraffin-silicone oil. The parts, freshly machined, are and simultaneously contacted. The surfaces are de delivered wetted with oil, and can be immediately greased by etching with diluted caustic soda and are treated, so that only a surface layer a few microns thick 15 given a preliminary cleaning. After vigorous rinsing in need be removed. m water, the water in removed by dipping into acetone After PER washing, PER vapor degreasing and rins and thereafter toluene, then the Ti support-structure ing in toluene under ultrasonic action (about 5 minto with the sheets, is immersed, under N2 gas, into the tal), the pretreated cylinders, wet with toluene, are electrolyte of Na(C2H5)3AlFAl(C2H3)3-3.0 toluene. placed, via an inert-gas lock, into the aluminum electro 20 In order to remove the oxide-hydroxide outer layer lyte bath. At a cathode movement of about 13 cm/sec, the aluminizing is carried out for 1.5 hours, with a that has developed through contact of the aluminum pulsed current of average current density of 12 with water, the sheets are anodically charged (i.e., elec mA/cm2 and a polarity-reversal cycle of 4:1, at 50 Hz. trically pre-treated by serving as the anode of a circuit) The galvano-Al layer thickness is about 15 microns and 25 for 10 min. The current density is 30 mA/cm2. The Ti has a fine-grained silver-bright appearance. structure is moved back and forth at 15 cm/sec; the The anodizing process is performed, after washing electrolyte (at 90) is mechanically stirred. The oxide with toluene, dipping into TRINORM "Al' and rinsing cover layer is thereby removed, together with a thin in water, in a CS bath of 18 C. for 20 min. (17.5V, 15 layer of aluminum. mA/cm2) and a crystal-clear eloxation layer of about 6 30 Immediately thereafter and in the same electrolyte, microns is obtained. The layer is solidified for 20 min. in the non-metallically-bare surfaces are coated in 55 min. superheated steam of 110° C. with a tightly-adhering galvano-Al layer about 20 mi High-purity aluminum and Raffinal, which are usu crons thick, employing polarity reversal with 20 ally the purest aluminum types technically available, are mA/cm2 average current density and the usual pulsed too soft for most technical structural applications and 35 do not have enough mechanical strength. During at current conditions (see Example 6). After washing with tempts to machining them mechanically by drilling, toluene, dipping in TRINORM "Al' and rinsing in milling, grinding and the like, they "smear' and warp. water, drying is effected with the aid of acetone. Their use in manufacturing is limited, except for press For anodizing only a portion of the surface, the rect ing, stamping and rolling processes. Among the alumi angular faces of the aluminized sheets are covered in num alloys, such as, for example, Al-Mg, Al-Cu, Al-Si selected areas with self-sealing, acid-resisting plastic and Al-Zn alloys which, due to their high strength, foil, cut in the shape of a design with cross-pieces 5 mm good mechanical workability and plasticity through in width. The sheets are now anodized in a 15 GX hot-pressing, forging and casting, have attained substan (direct current, oxalate acid) bath for 30 min., and an tial importance in automobile, ship and airplane con 45 eloxation layer approximately 12 to 15 micron thick is truction, the minor alloy constituents and impurities, produced on the exposed surface parts and edges. After specifically, Si, Mn, Cu, Fe, Pb, cause particular diffi thorough rinsing in water, the adhesive foil is pulled off, culties during anodizing because, e.g., of reduced hard the sheets are again washed and the GX eloxation layer ness on their inherent (natural) color. As a result of the is dyes in a SANDOZ color bath Al-black MLW (10 present invention, the same high-purity galvano 50 g/1) at 60° C. for about 5 min. Finally, the eloxation aluminum electroplated coating which has the valuable layers which are dyes black are solidified in boiling characteristics described above can be electroplated water for a period of 30 min. onto such alloys. The technology of aluminum applica The surface of the thus-partially anodized sheets is tions is considerably advanced thereby. not perfectly planar, because the surface of the eloxal EXAMPLE 7 55 layer is at a higher plane than the surface of that portion Electro-Aluminizing of Die-Cast Perforated Aluminum of the galvano-aluminum layer which was under the Plates masking foil. The depressions in the surface may be In a titanium frame structure, 3 perforated plates filled in as follows. Since eloxation layers are not at (100x60x3 mm) of the aluminum alloy DG Al Sil2, tacked during the anodic surface pre-treating process in are fixedly disposed with Tipoint contacts above their the aluminizing electrolyte, but a surface layer of the narrow edges, and surface-treated in a pressure-jet ap galvano-aluminum could well be removed, the afore paratus at a jet pressure of 5 atm. with electro-corun described surface treatment can be repeated in the elec dum (SN 120) suspended in oil. The subsequent washing trolyte and, thereafter, the galvano-aluminum surface and degreasing is done as in Example 6. The toluene 65 which was under the masking foil can be thickened up moistened parts are then electroplated with aluminum to the level of the GX eloxation surface by means of for 3 hours in a 100° C. aluminizing electrolyte bath of polarity reversal by electroplating additional aluminum triethylphenyl ammonium-chloride and 2,2 aluminum thereon. 4,148,204 17 18 sisting of TialV64 alloy, are arranged in 4 columns of 8 EXAMPLE 9 pieces each, and surface pre-treated by means of pres Electro-Aluminizing Of Titanium Strip And sure jets with silicon carbide (100 microns) in FRIGEN Surface-refining By Aluminum Diffusion 113 at a jet pressure of 8 atm. Strip titanium, e.g. type CONTIMET 30 or 35, 160 Following PER washing and toluene-rinsing, the mm wide and 0.5 mm thick, is passed for surface pre wobblers are placed into the aluminizing bath and are treatment and aluminizing on both sides through a strip coated with an approximately 15 micron galvano aluminum electroplating apparatus which operates con aluminum layer, accompanied by reciprocal movement tinuously. of the frame and rotation of the columns. The surface pre-treatment of the incoming titanium 10 Subsequently, they are intensively anodized (under strip may be done by means of pressure jets with 100 conditions as described above) and dyed in a SANDOZ micron silicon carbide particles suspended in trichlor color bath of Al-Blue LLW (2 g/l) at room temperature trifluorethane (FRIGEN 113) or a higher-boiling fluo for 2.5 min. The galvano-aluminum eloxation-layer ro-hydrocarbon at a jet pressure of 10 atm. with jet surface is solidified in boiling water for 30 min. and has nozzles being directed to both sides of the strip and 15 an homogeneous, light-blue and glare free appearance. under nitrogen gas. Alternatively, it may be done by This is particularly important when a uniform, deco means of liquid-drop impact erosion with FRIGEN 113 (density of 1.58 g/ml) or a liquid perfluoro-hydrocar rative surface appearance is required for an article fabri bon of greater density. In the first case, following sur cated of aluminum alloy, brass and titanium compo face pre-treatment with FRIGEN 113, the strip is 20 ments. washed free from particles and-in both instances EXAMPLE 11 dried under nitrogen gas. The metallically-bare titanium strip then enters an aluminizing electroplating cell con Punch-Pressed Parts Of Brass Sheet Coated On Both taining a suitable electrolyte and is coated on each side Sides With Electroplated Aluminum with about a 10 micron layer of galvano aluminum at a 25 A piece of brass strip 70 mm wide and 0.5 mm thick maximum current density of 60 mA/cm2 within a pas is surface-treated by etching for 30 seconds in a phos sage time of 10 min. To realize this relatively high depo phoric-acid containing etching solution, which is com sition rate, the cathode-anode spacing is reduced to 10 mercially available, for instance, from Schering AG, as mm and the electrolyte liquid is rapidly pumped-over in TRINORM "Fe". Then it is thoroughly washed with counter current flow between the titanium strip (serv 30 water, cathodically degreased in an alkaline or cyano ing as the cathode) and both aluminum anodes. alkaline bath (commercially available as UNAR 58 or The coated strip is rinsed with toluene and dried, and Degreasing Bath NORMAL) for about 20 seconds and the galvano-aluminum, in a loosely wound state, is dif pickled in 10-percent sulfuric acid. After intensive rins fused at 600 C. to a depth 5 to 10 microns in two hours. ing with deionized water for about 1 minute, the adher The surface pre-treatment, aluminizing and diffusion 35 ing water is displaced by immersing the brass sheet strip are conducted in the absence of hydrogen. in a dewatering bath (dewatering fluid commercially By analogy, the titanium alloys which increasingly available, for instance, as HAKUDREN), and the dry gain significance in turbine and motor construction, in strip is immediately immersed in toluene, where any rocket- and reactor technology as well as in aircraft residual dewatering fluid is removed under the action of construction, can be surface-refined. In the technically 40 ultrasonic vibration. important titanium alloys, aluminum is the alloying Still wet with toluene, the brass strip then is placed in component present in the greatest amount, e.g.: the aluminizing cell and is coated at a bath temperature of 70 to 90° C. and with the electrolyte comprising one Ti Al No C-1-1 7.5-8.5% Al, TA. No 74 6.5-7.3% Al, 45 part (CH3)3(C6H5)NIC, 2.2 parts of Al(C2H5)3, and 4 Ti Al 64 5,73-6.75% Al, parts of C6HsCH3, circulated by pumping, in an inert Ti Al On Z Mn 6-2-4-2 5.5-6.9% Al, atmosphere (N2 or Ar) free of air and moisture, between Raffinal plate electrodes (electrode spacing approxi since aluminum increases the strength of the titanium. mately 10 mm). Both sides of the strip are electroplated According to the method of the invention, the usually 50 with an aluminum coating about 30 microns thick. De readily workable, unalloyed titanium types, can now be pending on the motion of the electrolyte, current densi coated with galvano-aluminum. The diffusion of alumi ties of up to 0.04 A/cm2 with only a few volts of bath num into the surfaces of the article produces particu voltage, and deposition rates of up to about 40 microns larly hard titanium-aluminum alloys. Sheets of titanium per hour can be obtained. The electroplated aluminum used for the construction of containers and for aircraft 55 layer has a very fine-grained, silver-bright appearance can thus be covered with a harder, wear-resistant sur and adheres very well to the brass strip. face which has better heat resistance. Electroplated From the brass strip, retaining ring parts with a galvano-aluminum and galvano-aluminum eloxation 10-mm deep profile of 52 mm outside diameter and 22 layers on titanium surfaces increase the protection mm inside diameter are made on a punch press in one against corrosion, particularly against salt water, and 60 operation. The electroplated aluminum withstands the provide a functional and decorative surface refining of partially complicated forming process without the for the steel-hard light metal. mation of cracks and has assumed a shiny appearance at the heavily deformed portions. At the stamping edges, EXAMPLE 10 the shaping tool has pulled down the electroplated alu Electro-Aluminizing, Anodizing And Dyeing Of 65 minum over the height of the edge, so that the brass is Titanium Ti Alloy Wobblers no longer visible. The high ductility and the good ther In a pivoted titanium frame, cylinder wobblers, pro mal conductivity of the electroplated aluminum make vided with a longitudinal 7mm diameter bore and con possible a short cycling time of the stamping operation. 4,148,204 19 20 By means of hydraulically jetting with glass spheres cally no rust forms. The previously shiny aluminum of about 0.1 to 0.6 mm diameter, the electroplated alu surface appears merely spotty. This, too, can be avoided minum layer can be hammered smooth and burnished by a previously applied eloxal layer of 1 to 3 micron prior to stamping. After deformation, the parts exhibit a thickness. silver-bright luster on all sides. If the stamped edges are 5 well coated with electroplated aluminum (if necessary, EXAMPLE 14 the stamped edges can also be protected with a resistant Depth Measurements For Testing The Elongation lacquer) the parts can be eloxized in a GS (d-c sulfuric Behavior Of Steel Strip Coated With Electroplated acid) bath to a thickness of about 7 microns and, if de Aluminum sired, can be printed, or stained with a clear stain in 10 boiling water for 20 minutes. From the steel strip prepared according to Example 12, coated on both sides with electroplated aluminum, EXAMPLE 12 60 mm wide and 0.15 mm thick, pieces 75 mm long are Punch-Pressed Parts Of Sheet Steel Coated On Both cut and used for the depth measurement according to Sides With Electroplated Aluminum 15 Erichsen (DIN 50101). The measurements are carried A steel strip (60 mm wide by 0.15 mm thickness and out with a sphere of 20 mm diameter. comprising 0.33% Mn, 0.07% C, 0.04% Al, 0.023% S, In all test pieces, depressions between 8.5 and 9.0 mm 0.017% P, remainder Fe) is freed on both sides from its are measured and smooth cracks without separation thin oxide or scale layer by hydraulic jetting at 6 atm. from the steel base were observed. All values therefore gauge with corundum powder (80 microns particle 20 met the specified value for deep-drawing quality of the diameter) in oil. The thin strip rests alternatingly on a steel strip. flat steel support during this process. The metallic, bare steel strip protected against re EXAMPLE 15 newed oxidation and hydration by an oil film, is cleaned Deep-Drawing Of Shells Of Cold-Rolled Strip Coated by washing in liquid perchlorethylene and degreasing in 25 With Electroplated Aluminum Or Zinc perchlorethylene vapor and is immediately placed in toluene, where residual perchlorethylene is removed by Cylindrical shells of several millimeters to several ultrasonic action. The bare strip, still wet with toluene, centimeters inside diameter are customarily pressed or is then introduced into the aluminizing cell and coated deep-drawn from brass, copper or aluminum materials. in a vigorously agitated electrolyte (one part NaF, 2 30 In order to attain greater strength of thinner walls, parts Al(C2H5)3, 3.5 parts toluene) at a bath temperature ferrous materials (steels) have also been used, but the of 80-100° C., applying a pulsed current (50 Hz, cur stronger material poses greater fabrication difficulties rent density 0.015 A/cm2, anodic-cathodic loading ra and causes more tool wear. With auxiliary forming tion of 1:5) with about 20 microns of electroplated alu agents, the deep-drawing is made considerably easier minum. A silver-bright, finely crystalline, well-adhering 35 and technical advantages can be obtained, such as im electroplated aluminum layer is obtained, which allows provement of the drawing properties of the base mate a stamping process to be performed extremely easily rial, excellent dry-lubrication film, longer tool life, elim and rapidly. ination of intermediate annealing, working with thinner Instead of the above-mentioned anhydrons surface walls, and others. pretreatment, the steel strip can also be cleaned in a 40 Metals electroplated in accordance with this inven phosphoric-acid containing bath (commercially avail tion are advantageous auxiliary forming agents, which able as TRINORM "Fe') by etching, and then pre are paritucilarly well suited, for the manufacture of treated by cathodic degreasing with copper flash (less shells by deep-drawing. For this purpose, a cold-rolled than 1 micron, preferably 0.3 to 0.5 micron of copper) in steel strip of 1 to 2 mm thickness is coated, preferably in an alkaline bath. After washing with deionized water, 45 a continuous process, with 10 to 30 microns of electro the strip is dried with a dewatering agent (Dewatering plated aluminum or zinc. The layer thickness of the Fluid, commercially available, for instance, as HAKU electroplated metal depends on the degree of forming to DREN), given an after-rinse in a toluene rinsing bath, which the substrate metal is to be subjected. The elec and the copper-preplated steel strip is aluminized by troplated aluminum layer can be applied as described in electroplating as described above. 50 From both steel strips coated with electroplated alu Examples 11 and 12. With the same surface pretreat minum, deep-profile set rings, flanged cups, hollow ment, organo-zinc onium salt-complex electrolytes are profiled parts and the like can be produced in a particu used for the application of the electroplated zinc layer, larly advantageous manner on a stamping press. as for instance, can readily be prepared in accordance with German Pat. No. 1,200,817, i.e. EXAMPLE 13 55 one part (CH3)3(C6H5CH2)NF;2.2 parts of Corrosion Behavior Of Punched And Cut Edges. In Zn(C2H5)2; Steel Strip Coated With Electroplated Aluminum 2.5 parts of C6H5CH3, or From steel strip 0.15 mm thick, made according to one part (C2H5)4NCl; 2.2 parts of Zn(C2H5)2; Example 12 and coated on both sides with electroplated 3.0 parts of C6H5CH3, or aluminum, 50X50 mm test samples are punched and one part (CH3)4N]Cl; 2.2 parts of Zn(CH3)2; provided on two opposite sides with eight cuts each, 15 4.0 parts of C6H6 mm long. The test samples are then subjected to the At electrolyte temperatures of between 60 and 100' tropical-climate test at 40 C. and 100% air humidity for C., these electrolytes have conductivity values in the 400 hours. 65 range of 102 ohm cm-1 and permit depositions As a result of the electroplating of the pre-treated employing cathode current densities of 0.005-0.02 strip, the punched and cut edges are coated so well with A/cm2 and bath voltages of 2-10 V (depending on the electroplated aluminum, i.e., covered over, that practi electrode spacing), a pure, silver-bright electroplated 4,148,204 21 22 zinc in compact form on the substrate metal surface, cated in a stamping press to make covers, parts with with good adhesion and free of hydrogen. annular grooves, shells or the like. From the electroplated aluminum- or zinc-coated Having thus described the invention, we claim: cold-rolled strip, circular discs of 20 to 25 mm diameter 1. In a process of mechanically shaping metal articles are blanked out for deep-drawing shells of 16 mm diam 5 by drawing, embossing, extrucing pressing, punching, eter and 56 mm length and are fabricated in 6 drawing. rolling, squeezing and stamping, the improvement of operations in a multiple-plunger press into the above mentioned shells, which show a smooth to shiny silver pre-treating, prior to said shaping, the surface of said bright appearance. article by impinging with an anhydream, aprotic liquid O against the surface of said article by falling drops for the EXAMPLE 16 purposes of removing scale and exposing bright metal, Stamped Parts Of Brass Sheet Coated On Both Sides and subsequently electroplating, said article with alumi With Electroplated Indium num, cadmium, indium or zinc of the highest purity in After a surface pretreatment suited for the material, a an aprotic organo-metal liquid electroplating electro brass strip of 100 mm wide and 0.3 mm thick is coated 15 lyte essentially devoid of water and molecular oxygen. in organometallic electrolytic media, such as are de 2. The process of claim 1, in which said metal article scribed in the German Pat. Nos. 1,236,208, 1,170,658, is in the form of a thin sheet or strip and electroplated at each of its broad surfaces. 1,483,344 and 1,200,817 with a thin (10 to 20 microns) k is electroplated indium layer of 10 and subsequently fabri 20

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