Microstructure and Thermal Properties of Inert Plasma-Sprayed Tungsten Coating on SiC-Coated Carbon/Carbon Composites

The coating technology of tungsten on carbon/carbon (C/C) composite is an important issue for fusion experimental device components. In this study, an interlayer of chemical vapor deposition SiC between tungsten coating and C/C substrate was used. A tungsten coating 320 μm thick was successfully deposited on SiC-coated C/C substrate by inert plasma spray. The microstructure, roughness, and constituents of W-SiC-C/C composite materials were investigated using a scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffractometer, and atomic force microscope. The tungsten coating structure that may prevent crack propagation essentially consisted of a stacked lamellar columnar microstructure and particle cluster microstructures. The interfaces between the tungsten and SiC coating and between the SiC coating and the C/C were clear. The SiC interlayer acts as a barrier for carbon and tungsten diffusion. The thermal conductivity of the system was calculated by the mixture rule, which was 47.33 to 82.35 W/(m·K). The thermal expansion coefficient of W-SiC-C/C was negative at room temperature and up to 1.5 × 10⁻⁶/K for elevated temperature.