Evaluation test of C/C composites coated with SiC/C FGM, under simulated condition for aerospace application

The authors fabricated carbon/carbon composites coated with SiC/C functionally graded material (FGM). The fabricated specimens were hemispherical in shape with a diameter of 50 mm. They were tested in two kinds of heating devices to evaluate their durability. In hot gas flow tests, specimens were heated seven times for 30 seconds each before damage occurred. In arc-heated mind tunnel tests, a specimen was heated twice, 1,100 seconds each time, before damage appeared. Pinhole-Like damage was observed on the surface of all the specimens and pores were found in the carbon under the SiC coating layer by means of X-ray CT. The results of these evaluation tests demonstrated that the FGM layer has reasonable durability although the SiC coating is subject to damage due to oxidation.