Toughening effect and mechanical behaviour of SiC@SiO2 whisker-reinforced vitrified diamond composites

In this study, core-shell structured silica-coated silicon carbide (SiC@SiO2) whisker reinforced vitrified matrix composites with four distinct whisker concentrations were prepared by pressureless sintering. The effects of SiC@SiO2 core-shell filler on the morphology, mechanical properties, open porosity, and Rockwell hardness of the sample were investigated. The mechanical behaviour and void structures were correlated with the microstructure evolution, including the whisker/matrix interaction. When the whisker added fractions were 4 wt% (SiC whisker) and 3 wt% (SiC@SiO2 whisker), the flexural strength of the samples reached their maximum values of about 72.13 MPa and 71.60 MPa, respectively. Furthermore, the bending strength of the SiC@SiO2 whisker (2 wt%) reinforced vitrified composites was 71.51 MPa, and the open porosity and hardness were 23.69% and 48.5 HRB, respectively; these values were higher than those for the composites with the SiC whiskers (2 wt%). This result can be attributed to the protective coating of the SiO2 shell and the good wetting between the SiC@SiO2 filler and the glass bond.