Double Layer Oxidation Resistant Coating For Carbon Fiber Reinforced Silicon Carbide Matrix Composites

摘要

Double layer coatings, with celsian-Y_2SiO_5 as inner layer and Y_2Si_2O_7 as outer layer, were prepared by microwave sintering on the surface of carbon fiber reinforced silicon carbide matrix composite. Both celsian, Y_2SiO_5 and Y_2Si_2O_7 were synthesized by in situ method using BAS glass, Y_2O_3 and SiO_2 as staring materials. The sintering temperature was 1500 ℃, and little damage was induced to the composite. The composition and micrograph of the fired coating were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The oxidation and thermal shock resistance of samples with doubled-layered coating were characterized at 1400 ℃ in air. After 150 min oxidation and thermal cycling between 1400 ℃ and room temperature for 15 times, the weight loss of double layer-coated sample was 1.22% and there were no cracks in the coating.