Cast microstructure and tribological properties of particulate TiC-reinforced Ni-base or stainless steel matrix composites

Abstract

Particulate TiC-reinforced nickel, 304 stainless steel and IN-100 nickel-base superalloy matrix composites were processed by precipitating the carbide during solidification of a melt of appropriate composition at various cooling rates. The microstructure and tribological properties of prepared specimens were evaluated. The microstructures of these composites can be controlled by controlling melt composition and homogeneity, as well as cooling rate. The specific wear rate decreased with increasing volume fraction of carbide and decreasing carbide particle size and spacing. For given volume fraction of carbide and carbide particle size composites with a softer matrix exhibited a higher wear rate and vice versa. The difference in wear rate among the three types of composites slightly decreased with increasing volume fraction carbide. Microhardness increased with increasing volume fraction of carbide. The friction coefficient between a diamond stylus and the polished specimen surface decreased with increasing volume fraction of carbide and decreasing particle size and spacing. For given volume fraction of carbide and carbide particle size the friction coefficient decreased with increasing matrix microhardness. For all composites a lower friction coefficient corresponded to a higher wear resistance.