Microstructure evolution and tribological properties of TiB2/Ni–Ta cermets

Cermets containing TiB2 and single or mixed metals were produced by conventional hot-pressing technique at 2100 °C for 1 h. Nickel, tantalum and their mixtures were used as alloying substances to enhance the density of TiB2 composites. The influence of metal addition on the microstructure and tribological properties were investigated. The addition of Ta powder greatly refined the microstructure of sintered samples. Similarly, the mixture of Ni and Ta metals hindered the grain growth of TiB2 particles during the hot-pressing while the samples were sintered up to 98% of theoretical density. The wear behaviour of the composites was assessed by ball on disk tests. The wear rate against alumina counterbody varied in the range of (5.9–21.2) × 10−6 mm3/Nm. The friction coefficient was not affected significantly by the alloying substances and only slightly increased from 0.58 for pure TiB2 to 0.67 for samples with Ta addition.