Processing-Structure Relationships of Reactive Spark Plasma Sintered Diamond Composites

Traditional lightweight armor ceramics such as boron carbide (B4C) and silicon carbide (SiC) are used alone or together in varying amounts to create monolithic protective plates. These materials exhibit relatively small differences in hardness, flexure strength, and fracture toughness. Many of the routes taken during the synthesis of the powder and sintering of the plates using traditional ceramic processing techniques have long processing times, tend to leave asperities within the microstructure, and have unwanted secondary phases that lower the performance of these materials. In lieu of the incremental changes in the above properties, it is thought that adding diamond particulates to the ceramic matrix will dramatically improve the mechanical properties and overall performance. With the reduced cost of synthetic diamond and the commercial development of more rapid spark plasma sintering (SPS), this work develops a novel reactive SPS process to fabricate near fully dense SiC-TiC-diamond composites at various processing temperatures with minimal graphitization and full adhesion to the ceramic matrix. It was found that samples with up to ~97% theoretical density can be fabricated with no quantifiable graphite content within the characterization ability using advanced X-ray diffraction and microscopy techniques