Effect of liquid-phase content on the contact-mechanical properties of liquid-phase-sintered α-SiC

Effect of the content of the intergranular phase (Y₃Al₅O₁₂ or yttrium aluminum garnet or YAG) on the room-temperature contact-mechanical properties of pressureless, liquid-phase-sintered (LPS) α-SiC ceramics has been studied. An increase in YAG vol.% is found to result in the expected degradation of the elastic modulus and the indentation yield strength in LPS SiC. However, with increasing YAG vol.% the degradation in the hardness and the sliding-wear resistance is found to be severe, while the indentation toughness first increases and then decreases. These results are analyzed, and discussed in the context of providing guidelines for the design and fabrication of low-cost LPS SiC ceramics with tailored contact-mechanical properties.