The effect of additives on the densification and strengthening of titanium nitride (TiN) ceramics has been described. The additives studied were oxides (Al
2O
3, Y
2O
3 and MgO), nitrides (BN, AIN and Si
3N
4) and carbides (SiC and B
4C). The TiN compacts containing 5 and 10wt% additives were hot-pressed at 1950°C for 60min (except for Si
3N
4) in the ambient Ar gas of normal pressure. Additions of 10wt% Al
2O
3, 10wt% Y
2O
3 and 10wt% B
4C gave the relative densities of 97.4, 96.2 and 97.7%, respectively. The mechanical and electrical properties are as follows: 10wt% B
4C increased the hardness; 5wt% BN the flexural strength; 10wt% B
4C or 10wt% Y
2O
3 the values of fracture toughness (
KIC); 10wt% Al
2O
3 or 10wt% B
4C the Young's modulus and the rigidity; 10wt% B
4C the electrical conductivity. As a whole, 10wt% Al
2O
3, 10wt% Y
2O
3 and 10wt% B
4C additives contributed to both densification and strengthening. The most promising additive is 10wt% B
4C for TiN ceramics from the view point of relative density, mechanical and electrical properties, and prevention of grain growth.
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