Abstract
To improve the oxidation behavior of carbon/carbon composites, we developed a multilayer coating system by pack cementation and sol–gel slurry method. The coating consists of a BN–SiC inner dual-layer and a Si3N4–ZrO2–SiO2 outer barrier layer. The coating can effectively protect the C/C composites from oxidizing below 1500°C. Thermogravimetric analysis shows that the weight loss of the composites is less than 2.40wt.% after oxidizing at 1400°C for 220h. The whole temperature range oxidation resistance can be attributed to the multilayer protection design. The BN–SiC inner dual-layer can cure the cracks by producing borosilicate glass, and the Si3N4–ZrO2–SiO2 outer barrier layer can prevent the formation of cracks and seal the bubbles. The oxidation kinetics of the coated carbon/carbon composites shows that the Arrhenius curve consists of four parts, corresponding to four different oxidation processes and mechanisms in different temperature regions.
Published Version
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