Effect of diamond content on microstructure and properties of C/SiC-diamond composites

Phenolic resin slurry with different concentrations of diamond was introduced into porous carbon fiber-reinforced silicon carbide (C/SiC) composites, and corresponding C/SiC-diamond composites were obtained through the reactive melt infiltration process. The effects of diamond concentration on the microstructure, mechanical properties, and thermophysical characteristics of C/SiC-diamond composites were obtained through observation and analysis. The results indicated that with the increase of diamond concentration, more diamond particles were introduced into the composites; and the density, mechanical properties, and thermophysical properties of the composites were improved. The three-point bending strength of sample D10 (diamond concentration of 10 vol% in slurry) was 309.01 MPa, the coefficient of thermal expansion at 700 °C reached 2.69 × 10⁻⁶/K, and the thermal conductivity at room temperature reached 14.68 W/(m·K), which is much higher than twice that of C/SiC composites (5–6 W/(m·K)) prepared by chemical vapor infiltration.