Spark Plasma Sintering of ZrB2-Based Ceramic Reinforced with SiC Particles and Whiskers

Effects of silicon carbide as the reinforcement on densification and mechanical properties of zirconium diboride-based ultra-high temperature composites were studied. A monolithic ZrB2 ceramic (as the baseline) and three ZrB2-based composites reinforced with 25 vol% SiC in different morphologies (particulate, whisker and particulate/whisker mixture) were fabricated by spark plasma sintering route. The sintering process was conducted at 1900 °C for 7 min under 40 MPa. A relative density of ~96% was obtained for the ZrB2 ceramic but the other composites approached their theoretical densities. The hardness and fracture toughness values of SiC reinforced samples were higher than those for the monolithic one. The simultaneous addition of SiC particulates/whiskers showed a synergistic effect on the enhancement of mechanical performance of composite.