Effect of Gradient TiC–Ti5Si3–TiSi2 barrier layer on SiC in SiC–borosilicate glass composites

Abstract

The oxidation of SiC in SiC–borosilicate glass composites releases gases which cause a high volume expansion ratio and low bending strength and limits the application of the composites as packaging materials. To solve this problem, we deposited a Ti compound coating on SiC by heating a mixture of TiH2 and SiC particles at 750°C for 1h under vacuum. The thickness of the coating was about 200nm, and the coating was a gradient TiC–Ti5Si3–TiSi2 barrier layer according to the result of the X-ray diffraction. The coated SiC had a better anti-oxidation ability than uncoated ones in borosilicate glass, and as a result, the volume expansion ratio of the composites with 25vol.% coated SiC was reduced by 287%, and the bending strength was increased by 117%. The composites with 55vol.% SiC had the maximum thermal conductivity (14.2Wm−1K−1) and rather low thermal expansion coefficient (4.98×10−6).