C/SiC–ZrB2–ZrC composites fabricated by reactive melt infiltration with ZrSi2 alloy

C/SiC–ZrB2–ZrC composites were prepared by reactive melt infiltration (RMI) combined with vacuum pressure impregnation (VPI) method. B4C–C was first introduced into C/SiC composites with a porosity of about 30% by impregnating the mixture of B4C and phenol formaldehyde resin, followed by pyrolysis at 900 °C. The molten ZrSi2 alloy was then infiltrated into the porous C/SiC–B4C–C to obtain C/SiC–ZrB2–ZrC composites. The flexural strength was tested. The ablation behavior was investigated under an oxyacetylene torch flame. It has been found that the C/SiC–ZrB2–ZrC showed a high flexural strength and an excellent ablation resistance. The reactions between ZrSi2 alloy and B4C–C were studied, and a model based on these reactions was built up to describe the formation mechanism of the matrix.