Microstructure and Failure Behavior of Double Anti-Oxidation Coating on SiCf/SiC-CMC

Abstract In this paper, BN interfacial phase was prepared on SiC fiber surface and CVD SiC gradient coating was prepared on the surface of SiCf/SiC-CMCs composite. CVD SiC coatings were fabricated by the pyrolysis of methyltrichlorosilane (MTS) in hydrogen at a low pressure of 5-10kPa. The ratio of MTS to hydrogen is 1 to 12.Oxidation behaviour is examined by placing the material with coats in air. The oxidizing temperatures were varied from 100°C to 1200°C. Optical microscope and SEM were used to observe the surface morphology and microstructure of coatings. XRD was used to characterize the phase composition. The results indicated that the Oxidation of SiC/SiC-CMC is the most serious at 800°C. Tensile strength test shows that the fracture strength of the material is the lowest and with the increase of temperature to 1200°C, the tensile strength of the material increases. Tensile strength test shows that the fracture strength of the material is the lowest and with the increase of temperature to 1200°C, the tensile strength of the material increases.