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Pencil Hardness Measuring Coating Mechanical Properties CTT 2019 Rahul Nair Fischer Technology, Inc. 2018 1 Coating Mechanical Properties Characterization Nanoindentation Progressive Load Scratch Fischer Technology, Inc. 2018 2 Characterizing Surfaces Treated surfaces Coatings and Thin Films Composites Fischer Technology, Inc. 2018 3 Coating Mechanical Properties Characterization Fischer Technology, Inc. 2018 4 Coating Mechanical Properties Characterization H a r d n e s s I C r e e p I E l a s t i c i t y I U n i a x i a l M e c h a n i c a l R e s p o n s e I Te n s i l e S t r e n g t h and Te n s i l e S t r e s s I S t i f f n e s s in Te n s i o n - Yo u n g ’ s M o d u l u s I T h e P o i s s o n E f f e c t I S h e a r i n g S t r e s s e s and S t r a i n s S t r e s s - S t r a i n C u r v e s Thermodynamics of M e c h a n i c a l R e s p o n s e I E n t h a l p i c R e s p o n s e I E n t r o p i c R e s p o n s e I Viscoelasticity I S t i f f n e s s I K i n e m a t i c s : the S t r a i n – Displacement R e l a t i o n s I Equilibrium : the S t r e s s R e l a t i o n s I Transformation of S t r e s s e s and S t r a i n s Constitutive I Y i e l d and P l a s t i c F l o w I M u l t i a x i a l S t r e s s S t a t e s I E f f e c t of Hydrostatic P r e s s u r e I E f f e c t of Rate and Temperature I C o n t i n u u m P l a s t i c i t y I T h e Dislocation B a s i s of Y i e l d and C r e e p K i n e t i c s of C r e e p in Crystalline M a t e r i a l s I F r a c t u r e I A t o m i s t i c s of C r e e p R u p t u r e I F r a c t u r e M e c h a n i c s - the E n e r g y - B a l a n c e A p p r o a c h I the S t r e s s I n t e n s i t y A p p r o a c h I F a t i g u e Fischer Technology, Inc. 2018 5 Characterizing Surfaces Mechanical Properties of these coatings is greatly influenced by several factors i. Chemistry ii. Deposition Technique iii. Curing Procedure iv. Aging and Weathering- Thermal, Oxidative and UV v. Environmental Conditions- Temperature and Humidity Fischer Technology, Inc. 2018 6 Traditional Hardness Testing Hardness – resistance to penetration of a hard indenter Fischer Technology, Inc. 2018 7 Traditional Hardness Testing- Mohs Scale The ability of one solid to scratch another or to be scratched by another solid Austrian mineralogist Friedrich Moh, 1812 Fischer Technology, Inc. 2018 References -1. http://www.hautehorlogerie.org/en/glossary/mohs-scale-187/ 8 Traditional Hardness Testing- Pencil Hardness These alternate techniques are inexpensive Pencil hardness Handheld Hardness Testers Scratch Testers for Scratch Hardness BUT…. Fischer Technology, Inc. 2018 9 Traditional Hardness Testing- Pencil Hardness i. Study to check the variability in the standard Pencils used in Pencil hardness testing ii. Our nanoindentation tester used to measure Martens Hardness of standard Pencils iii. At higher hardness range there is inconsistency of the pencil hardness of the standard pencils iv. Even at lower hardness levels pencil hardness of standard pencils overlaps v. Additionally, more uncertainty introduced by influence from user Fischer Technology, Inc. 2018 10 Traditional Hardness Testing- Brinell Apply fixed load & Optical measure of the residual print area - Swedish engineer Johan August Brinell in 1900 Fischer Technology, Inc. 2018 References -1. http://www.precisiontestingequip.com/p1_02_3.html 2. http://en.wikipedia.org/wiki/Brinell_scale 11 Traditional Hardness Testing- Rockwell Apply fixed pre-load, Apply fixed load & Penetration depth measurement - Patented by Hugh M. Rockwell and Stanley P. Rockwell from CT in 1914 Fischer Technology, Inc. 2018 References -1. http://www.wilson-hardness.com/Products/RockwellTesters.aspx 12 Traditional Hardness Testing- Vickers & Knoop Apply fixed load & Optical measure of the residual print area - 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd in Britain Optical measurement Application of a fixed load of the indentation Fischer Technology, Inc. 2018 References -1. http://www.instron.us/wa/applications/test_types/hardness/vickers.aspx 13 Traditional Testing- E-Modulus (Young’s modulus) ideal elastic behaviour of solid states : Hooke‘s law (1676) ideal spring : tensile test (e.g. steel) F = k.x F stress : A k: spring constant k l F (l l0 ) *100% 0 strain : l0 D k 2Dl Dl *100% l F l x 2 0 F E const. matter constant E [Nmm-2] (Young’s Modulus, 1807) Fischer Technology, Inc. 2018 14 Limitations of Traditional Hardness Testing • In applications where treated surfaces, coatings, thin films or composites are tested • shows substrate influence • indent may be too small to observe with a microscope • (Soft) imprint on elastic materials may be too small to observe with microscope • Testing big volumes of material can be time consuming • Only hardness can be calculated Coating Large Stress Base Material Field Fischer Technology, Inc. 2018 15 Principles of Nanoindentation . Apply a load (F) incrementally until a Force Actuator maximum is reached . Result: h=f(F,t) F . Martens hardness HM is calculated as a Displacement Sensor function of depth . The load decrease curve is used for the calculation of material parameters Indentation Modulus Eit, Indentation Hardness Hit Indenter . ISO14577 and ASTM E2546 Test Specimen Fischer Technology, Inc. 2018 16 Principles of Nanoindentation Apply a load (F) incrementally until a maximum is reached Result: h=f(F,t) Martens hardness HM is calculated as a function of depth The load decrease curve is used for the calculation of material parameters Indentation h=f(F,t) Modulus Eit, Indentation Hardness Hit Fischer Technology, Inc. 2018 17 Principles of Nanoindentation ideal elastic ideal plastic (rubber, spring) (modeling clay) h h elastic + plastic h F F F Fischer Technology, Inc. 2018 18 Indentation hardness : Calculation of Vicker Hardness Fmax Indentation Creep H IT ( HV H IT *0.0945 ) AP (hc ) h2 h1 CIT1 * 100 h2 Indentation modulus Unloading 2 1s hmax Martens hardness EIT 2 1 1i Er Ei Loading h, indentation depth S Er Indentation Recovery 2 AP (hc ) Fischer Technology,h2 Inc. 2018h1 CIT2 * 100 F, applied force (load) h2 19 Dynamic Nanoindentation Storage and loss moduli, loss tangent Fischer Technology, Inc. 2018 20 Advantages of Nanoindentation . Wide variety of Materials: Applies low load - Measure shallow depths . No optical measurement: no influence of the user . The instrumented indentation test yields more information than classical hardness measurements . Indentation Hardness HIT . Martens Hardness . Indentation Modulus EIT . Work Done- Elastic and Plastic . Creep CIT . Vickers and Knoop Hardness 10% . Fracture Toughness . Pop-in and Pop-out . Storage and Loss moduli . Glass Transition . Mechanical Properties Mapping Fischer Technology, Inc. 2018 21 Nanoindenter Form Factor – Base Instrument Reliable, cost-effective, user-friendly instrument to measure hardness, elastic modulus, creep and much more of coatings and bulk material Automated surface Ample load and depth range; detection for higher broad range of applications productivity Minimal sample preparation due to open layout Solid granite base with specialized vibration Compact design makes the isolation silicone feet to HM2000S an ideal tool for reduce noise all environments Fischer Technology, Inc. 2018 22 Nanoindenter Form Factor – Fully Equipped Feature-packed, user-friendly instrument to measure hardness, elastic modulus, creep and much more of coatings and bulk material Minimal sample preparation Motorized z-axis and due to large working area fully-automated surface and open layout detection for higher productivity Enhanced high resolution optical system with autofocus and Same measuring head as multiple objective turret HM2000 S Measure on smallest structures, cross-sections Custom granite structure with high precision for enhanced frame programmable xy-table stiffness and low noise Fischer Technology, Inc. 2018 23 Factors that effect Nanoindentation Advantage Cone . Protects Indenters & Speeds up Indentation . Software algorithms to auto detect surface Fischer Technology, Inc. 2018 24 Factors that effect Nanoindentation Advantage Cone . Low Thermal Drift . Low Frame Compliance Fischer Technology, Inc. 2018 25 Base Instrument Application: Automotive Paint and Clear Coats Measurement of two 80 µm thick 2K automotive repair paints • Max. indentation depth < 6.5 µm 2K automotive repair HM E IT paints Samples N/mm² GPa Mean value Sample A 42.9 1.4 Sample B 143.0 3.1 Standard deviation Sample A 1.2 0.1 Sample B 5.6 0.1 Fischer Technology, Inc.
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