Mechanical and Tribological Behaviors of Hot-Pressed SiC/SiCw-Y2O3 Ceramics with Different Y2O3 Contents

Sintering additives are commonly used to reduce the conditions required for densification in composite ceramics without compromising their performances simultaneously. Herein, SiC/SiCw-Y2O3 composite ceramics with 10 vol.% SiC whiskers (SiCw) and different Y2O3 contents (0, 2.5, 5, 7.5, and 10 vol.%) were fabricated by hot-pressed sintering at 1800 degrees C, and the effects of Y2O3 content on the microstructure, mechanical properties, and tribological behaviors were investigated. It was found that the increased Y2O3 content can promote the densification of SiC/SiCw-Y2O3 composite ceramics, as evidenced by compact microstructure and increased relative density. The Vickers hardness, fracture toughness, and flexural strength also increased when Y2O3 content increased from 2.5 vol.% to 7.5 vol.%. However, excessive Y2O3 (10 vol.%) aggregated around SiC and SiCw weakens its positive effect. Furthermore, the Y2O3 additive also reduces the coefficient of friction (COF) of SiC/SiCw-Y(2)O(3)3 composite ceramics, the higher the Y(2)O(3)3 content, the lower the COF. The wear resistance of SiC/SiCw-Y2O3 composite ceramics is strongly affected by their microstructure and mechanical properties, and as-sintered SiC ceramic with 7.5 vol.% Y2O3 (Y075) shows the optimal wear resistance. The relative density, Vickers hardness, fracture toughness, and flexural strength of Y075 are 97.0%, 21.6 GPa, 7.7 MPa center dot m(1/2), and 573.2 MPa, respectively, the specific wear rate of Y075 is 11.8% of that for its competitor with 2.5 vol.% Y2O3.