C/SiCZrB ₂ZrC composites fabricated by reactive melt infiltration with ZrSi ₂ alloy

C/SiC-ZrB ₂-ZrC composites ere prepared by reactive melt infiltration (RMI) combined with vacuum pressure impregnation (VPI) method. B ₄C-C was first introduced into C/SiC composites with a porosity of about 300% by impregnating the mixture of B ₄C and phenol formaldehyde resin, followed by pyrolysis at 900°C. The molten ZrSi ₂ alloy was then infiltrated into the porous C/SiC-B ₄C-C to obtain C/SiC-ZrB ₂-ZrC composites. The flexural strength was tested. The ablation behaxior was investigated under an oxyacetylene torch flame. It has been found that the C/SiC-ZrB ₂-ZrC showed a high flexural strength and an excellent ablation resistance. The reactions between ZrSi ₂ alloy and B ₄C-C were studied, and a model based on these reactions was built up to describe the formation mechanism of the matrix.