Wear mechanism of composites based on titanium nitride

Abstract

UDC 621.762Electron scanning microscopy, Auger spectroscopy, and x-ray diffraction analysis are used to examine the wear mechanism of new antifriction composites based on titanium nitride during friction on steel in air without lubrication. It is established that the TiN lattice parameter decreases in friction regardless of the lubricant composition. This is due to the partial replacement of nitrogen atoms by oxygen atoms and the formation of titanium oxynitride, which substantially increases the wear resistance of materials.As loading and velocity increase, the mixed or dry frictional interaction between the sample and the counterface changes over from macro-to microlevel (molecular, atomic), causing the adhesion component of the friction force to increase [1,2]. To improve the tribological properties of materials, the adhesion component should be minimized. This may be accomplished by selecting the friction couples with low adhesion activity, developing special structure of material, and ensuring the formation of dense separating films with high adhesion strength. We showed previously [3-5] that titanium nitride and materials on its basis with a steel counterface most fully complied with these requirements. However, the nature of high wear resistance and wear mechanism of these materials still have to be examined.The objective of this paper is to examine the wear mechanism and its effect on the tribological properties of composites based on titanium nitride under dry friction on steel in air.To produce materials based on titanium nitride, components were sintered in the presence of a liquid phase (matrix materials) or presintered refractory skeletons were impregnated (skeletal materials). As a binder, 60BrO10S10-40(Cu-Ni) alloy and Ni 3 Al were used. Graphite, as a solid lubricant, was introduced into the composites to improve their tribological properties.Tribological shaft-bush tests were conducted using an MT-68 friction machine under a load of 1 MPa and at velocities no more than 25 m/sec in pair with hardened steel 65G; reference tests were performed under a load of 1 MPa and a velocity of 10 m/sec. The friction surfaces were examined with a MIM-8 microscope, SCAN-S4-10 electron microscope, JAMP-10S Auger spectral microprobe (JEOL), and DRON-UM1 diffractometer.