Effect of Ti₃AlC₂ addition on the densification and high- temperature erosion resistance of TiB₂ composite ceramics fabricated by SPS

TiB₂-Ti₃AlC₂ composite ceramics were fabricated by spark plasma sintering (SPS) technique. The effects of Ti₃AlC₂ additive on the densification, mechanical properties and resistance to high-temperature aluminum liquid erosion of composite ceramics were investigated, and the mechanisms of densification and erosion resistance were highlighted, respectively. At sintering temperature of 1800 °C, pressure of 40 MPa, and holding time of 10 min, TiB₂ composite ceramic with 40 wt% Ti₃AlC₂ acquired 98.9 % densification, 98.2 % thermal shock resistance, and 13.71 MPa∙m^1/2 fracture toughness. The in-situ decomposition of Ti₃AlC₂ was clearly observed during the sintering process, and the generated liquid Al induced the liquid phase sintering mechanism, promoting the densification of composite ceramics. Besides, the simultaneous in-situ generation of TiC phase strengthened the TiB₂ matrix and induced a mixed toughening mechanism of transgranular fracture and intergranular fracture, resulting in superior mechanical properties and better resistance to high-temperature erosion of TiB₂-Ti₃AlC₂ composite ceramics.