Effects of SiC on the Microstructure, Densification, Hardness and Wear Performance of TiB2 Ceramic Matrix Composite Consolidated Via Spark Plasma Sintering

Monolithic TiB2 are known to have a good combination of densification and hardness, which are sometimes helpful but limited in application. However, their usage in service at elevated temperatures such as in thermal power plants, cutting tools, tribological purposes (mechanical seals, blast nozzles, wheel dressing tools), etc. leads to catastrophic failure. Hence, the introduction of sintering additives in the TiB2 matrix greatly influences the sinterability and properties (fracture toughness, wear resistance, etc.) of the resulting composite needed to meet the requirement for various industrial applications. In this study, the influence of SiC as sintering additives on the microstructure, densification, hardness and wear performance of TiB2 ceramic was observed. Hence, TiB2, TiB2-10wt%SiC and TiB2-20wt%SiC were sintered at 1850 degrees C for 10 min under 50 MPa. The impacts of SiC on the TiB2 were observed to improve the microstructure and correspondingly improve the densification and mechanical properties, most especially with the composite with 20wt% SiC. Combined excellent densification, hardness and fracture toughness of 99.5%, 25.5 GPa, 4.5 MPa.m(1/2) were achieved, respectively, for TiB2-20wt%SiC. Diverse in-situ phase and microstructural alterations were detected in the sintered composites. It was discovered that the in-situ phase of TiC serves as the contributing factor to the enhanced features of the composites. Moreover, the coefficient of friction and wear performance outcomes of the synthesized composites described a decreased coefficient with an enhanced wear resistance via the increasing SiC particulate. However, applying the load from 10 to 20 N increased the wear rates.