Wear Resistance of Ti-40Zr Alloy with TiN and ZrN Multilayer Coatings

Abstract

Production and processing of titanium alloys are expensive and its alloys show low wear resistance. Substrates of Ti-40Zr, used for orthopedic implants, were obtained from the elemental mixture of hydrogenated powders, followed by a sequence of cold uniaxial and isostatic pressing and vacuum sintering. Aiming wear resistance increase, samples were coated by physical vapor deposition using electron beam technique (EB-PVD). Multilayer coatings with three different configurations were undertaken: Ti/TiN, Ti/TiN/ZrN and Ti/TiN/ZrN/TiN. Micro-abrasive wear tests were conducted by ball-cratering, with abrasive slurry of silicon carbide (SiC). The wear craters were measured at intervals corresponding to increments in the sliding distance of approximately 14 m. Range of the normal force were between 0.35 and 0,45 N. Scanning electron microscopy was used to evaluate the wear crater and the wear mode. All experiments showed three-body abrasive wear and a reduction of one order of magnitude in wear coefficient for two coated samples: 2,58∙10-12m³(Nm)-1to substrate, 5,4∙10-13m³(Nm)-1to Ti+TiN film and 7,22∙10-13m³(Nm)-1to Ti+TiN+ZrN film. In the Ti+TiN+ZrN+TiN experiment the wear coefficient of film is nearer to the substrate, 7,58∙10-13m³(Nm)-1. The multi-layers containing ZrN presented wear coefficient higher than Ti/TiN films, possibly due to existing residual stresses.

Effect of Different ZrN Addition on Microstructure and Wear Properties of Titanium Based Coatings by Laser Cladding Technique

“…When the contents of N excess its solid solution limit, nitrides are precipitated in alloy, which can further strengthen the matrix [16], because the interface between these in situ phases and alloy matrix is coherent, which will not easily pull out during wear [17]. As it is well-known, ZrN is widely used in the coating of tool steels to improve their wear resistance [18][19][20][21][22]. For example, Floroian et al [20] and Dias et al [21] synthesized ZrN wear-resistant coating on the surface of titanium alloy to improve the corrosion resistance of the alloy matrix.…”

“…As it is well-known, ZrN is widely used in the coating of tool steels to improve their wear resistance [18][19][20][21][22]. For example, Floroian et al [20] and Dias et al [21] synthesized ZrN wear-resistant coating on the surface of titanium alloy to improve the corrosion resistance of the alloy matrix. In a previous study, Yang et al [22] indicated that ZrN powders (<12 wt.%) could fully melt and completely dissolve in TC11 alloy, which enhances the microhardness and wear resistance of coating without changing the microstructures of the substrate.…”