COMPOSITE MATERIALS IN THE TiN–Cr₃C₂–C–MATRIX SYSTEM

Abstract

The influence of modifying additives on the strength and tribological properties of titanium nitride composites has been examined. The lowest contact angle (25−30º) is shown by the PG12N-01 alloy, containing chromium, boron, silicon, and carbon. Relatively porousless structures can be obtained in the TiN–PG12N-01 system when chromium carbide and carbon are introduced into the composite as graphite, which contributes to the formation of TiCN, improving wetting and adhesion. Graphite, introduced additionally as an impurity, remains after sintering as a separate uniformly distributed phase integrated into the composite overall structure. In this state, graphite can successfully act as a dry lubricant, improving the operational characteristics. In addition, it activates sintering of the composite allowing it to become almost porousless. The optimum sintering temperature falls in the range 1450–1500 ºС depending on the carbon and metal matrix contents. The strength of the resultant composites was 300–500 MPa and hardness 16.1 GPa. The highest strength can be reached through an optimum combination of graphite and PG12N-01 matrix. The mechanical characteristics deteriorate when the amount of these components is higher or insufficient. The antifriction characteristics of the materials were tested by dry end friction (at a rate of 8 m/sec, 50 MPa pressure in the contact areas, and 10 km sliding path) against a 65G steel counterface with 60 HRC hardness: friction coefficient was found to be 0.27−0.3 and wear resistance 0.2 ± ± 0.02 µm/km. Thus, the developed ceramic materials have high strength and antifriction characteristics and can be used in dry friction conditions at high speeds and loads.