Pressureless sintering and mechanical properties of titanium nitride-titanium diboride particulate ceramic composites

Titanium nitride has an attractive combination of engineering properties such as high hardness, high melting point, high corrosion resistance, and good electrical and thermal conductivity. In spite of these properties, the use of titanium nitride as a bulk ceramics has received little attention due to its poor sinterability, sensitivity of bulk properties to the processing conditions and the need for pressure-assisted sintering.; The primary objective of this research was to develop a pressureless reaction sintering process for titanium nitride using boron carbide as an additive. The resultant ceramic is a composite consisting of titanium nitride and titanium diboride as the matrix and reinforcing particulate phase, respectively. The secondary objective was to determine the role of the titanium diboride formed during sintering on the mechanical properties of the composites.; The highest sintered density obtained with a boron carbide addition of 2 ∼ 4 wt.% and at a sintering temperature of 2000°C was 95.9% of the theoretical density. The highest flexural strength was 415 MPa, the fracture toughness was 3.19 MPa × m1/2 and hardness was 12.8 GPa were obtained for composites with 6 wt.% of boron carbide addition.