An investigation into the microstructural and mechanical properties of the ZrB₂/SiC composites prepared by silicon infiltration

In this study, the synthesis of ZrB₂/SiC composite was carried out via infiltration of silicon melt into a ZrSiO₄/B₄C preform, and the effect of different ratios of ZrSiO₄/B₄C and C/ZrSiO₄ was investigated on phase and microstructural properties. For this purpose, stoichiometric ratios of raw materials and 10 wt% phenolic resin were used to induce the porosities in the preform. Then the powder mixture was milled and pressed. To perform pyrolysis reaction, it was placed in a vacuum-controlled atmosphere furnace with argon gas at 650 °C and then the Si infiltration process was performed at 1650 °C for 1 h. The hardness, density, and elastic modulus of the samples were measured. The optimum results were obtained for the composite sample with a ZrSiO₄/B₄C ratio of 4, which had a density of 5.28 g cm⁻³, elastic modulus of 423 GPa, and hardness of 33.28 GPa. Moreover, scanning electron microscopy and x-ray diffraction analyses confirmed a uniform distribution of ZrB₂ and SiC phases and the absence of undesirable phases in the sample, respectively. (paper)