The Mechanical Properties of Hot-Pressed TiN Ceramics with Various Additives

Abstract

The effect of additives on the densification and strengthening of titanium nitride (TiN) ceramics has been described. The additives studied were oxides (Al2O3, Y2O3 and MgO), nitrides (BN, AIN and Si3N4) and carbides (SiC and B4C). The TiN compacts containing 5 and 10wt% additives were hot-pressed at 1950°C for 60min (except for Si3N4) in the ambient Ar gas of normal pressure. Additions of 10wt% Al2O3, 10wt% Y2O3 and 10wt% B4C gave the relative densities of 97.4, 96.2 and 97.7%, respectively. The mechanical and electrical properties are as follows: 10wt% B4C increased the hardness; 5wt% BN the flexural strength; 10wt% B4C or 10wt% Y2O3 the values of fracture toughness (KIC); 10wt% Al2O3 or 10wt% B4C the Young's modulus and the rigidity; 10wt% B4C the electrical conductivity. As a whole, 10wt% Al2O3, 10wt% Y2O3 and 10wt% B4C additives contributed to both densification and strengthening. The most promising additive is 10wt% B4C for TiN ceramics from the view point of relative density, mechanical and electrical properties, and prevention of grain growth.