Fe-TiC/N Ceramic-Metal Composites

Abstract

A fine powder consisting of iron metal and titanium carbide or nitride can be obtained by reduction of the mineral ilmenite (FeTiO₃) with carbon under controlled atmospheres. Hot-pressing of Fe-TiC powder causes transformation of ≈ 80% of the α-Fe to Fe₃C, whereas for Fe-TiN powder the extent of transformation to Fe₃C is very minor. The densification process is controlled by the extent to which the ceramic is wetted by the metal matrix and has been found to be very different between TiN and TiC-based systems. Microstructural examination of these specimens shows retention of sharp (cubic) TiN grain boundaries in Fe-TiN whereas the TiC grains in Fe-TiC are heavily rounded. Physical property measurements for hot-pressed specimens show that density and hardness increase with temperature while porosity reduces to zero by ≈ 1330°C for Fe-TiN and ≈ 1530°C for Fe-TiC. Vickers hardness values of ≈ 1100 and ≈ 1380 are obtained for fully dense specimens of Fe-TiN and Fe-TiC respectively.