Effect of difference in microstructure of rare refractory metal silicate doping matrix on oxidation behavior and mechanism of C/SiC composites

Doping refractory metal silicates into the matrix of C/SiC composites is an effective means to improve their oxidation resistance. Previous studies have demonstrated that doping HfSiO4 matrix availably enhanced the oxidation resistance of C/SiC composites, but the high raw material cost of HfSiO4 limits its widespread application. This paper attempts to introduce ZrSiO4 matrix, which has lower raw material cost and similar properties to HfSiO4, into C/SiC matrix through the same process. To clarify whether the microstructure of the refractory metal silicate doped matrix significantly impacts the oxidation behavior of C/SiC composites, the preparation temperature of ZrSiO4 was increased to 1100°C. The densification effect, oxidation behavior, and related mechanisms of C/SiC composites doped with ZrSiO4 matrix were investigated and compared in detail with the previously studied C/SiC composites doped with HfSiO4 matrix. Results show that the oxidation resistance behavior of C/SiC composites is relatively sensitive to the microstructure of the refractory metal silicate-doped matrix. At lower preparation temperatures of refractory metal silicates, the particle size of the composite matrix is significantly refined, which is conducive to improving the matrix densification degree of the composites and protecting more carbon fibers from erosion by the oxidizing environment, thus achieving a better oxidation resistance modification effect.