Nanoindentation and instrumented scratching measurements on hard coatings
- National Inst. of Standards and Technology, Gaithersburg, MD (United States). Ceramics Div.
Elastic, plastic, and cracking properties of ZrO{sub 2}, a ZrO{sub 2}-metal composite, and a Ni-NiO composite, all plasma-sprayed as coatings on metallic substrates, have been studied. Data comparisons were made with bulk ZrO{sub 2}, bulk nickel, and single-crystal silicon as reference materials. A nanoindentation and scratching apparatus was used for the measurements. Three different indenter and scratching tool shapes were used: 200 {micro}m radius sphere, Vickers four-sided pyramid, and a 45{degree} wedge with a 0.5-mm radius curved edge. During indentation, over a load range of 10 mN to 1 N, continuous load versus depth data were obtained in each case to permit analysis for material hardness and elastic modulus. The loading curve data are used to calculate hardness, and the unloading curve data are used to calculate elastic modulus. The analytical models used as described and compared. An alternate method for deriving elastic modulus from the initial portion of the loading curve is described. Comparison among the results for different tool shapes will be discussed. During instrumented scratching over a similar load range, values for load, tool depth, and scratch-resisting force were continuously measured. The applied load was either held constant at one or more selected values, or linearly increased during scratching. This load variation permitted identification of critical loads for severe cracking damage of the brittle materials. Scanning electron microscope (SEM) studies were used to characterize the cracking damage. The critical load values depended on tool shape and material microstructure. The studies identified damage mechanisms in the hard coatings, and critical loads for damage initiation. Damage morphology typically involved local surface cracking, edge chipping, and plastic deformation. The relative proportions of cracking and plastic response seemed to vary with tool shape, material, and microstructure.
- OSTI ID:
- 611630
- Report Number(s):
- CONF-9412140-; ISBN 0-8031-2036-2; TRN: IM9816%%104
- Resource Relation:
- Conference: Symposium on effect of surface coatings and treatments on wear, Phoenix, AZ (United States), 7 Dec 1994; Other Information: PBD: 1996; Related Information: Is Part Of Effect of surface coatings and treatments on wear; Bahadur, S. [ed.] [Iowa State Univ., Ames, IA (United States)]; PB: 166 p.; ASTM special technical publication, 1278
- Country of Publication:
- United States
- Language:
- English
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