TIAN Wei ¹, LI Xuhua ², ZHANG Hongliang ³, WANG Kunjie ¹, ZHANG Zhaofu ¹

(1. Xi’an Aerospace Composites Research Institute, Xi’an 710025, Shaanxi, China; 2. Academy of Aerospace Solid Propulsion Technology, Xi’an 710025, Shaanxi, China; 3. The 8th Military Representative Office of Air Force Equipment Department in Xi’an, Xi’an 710065, Shaanxi, China)

Abstract: To improve the erosion resistance of carbon-based facing materials during plasma instabilities, a series of TiC/C composites were prepared on C/C substrates via chemical vapor deposition (CVD). Microstructure and composition of the samples after long pulse plasma discharge in HT-7 tokamak were characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Distinct eroded pits were observed in the C-rich TiC/C coatings, but no cracks were present. On the contrary, the eroded pits were ambiguous in the case of pure TiC coating, but large cracks were observed. On the basis of these results, TiC/C functionally graded materials were further prepared, whose residual thermal stresses and deformation were then analyzed by using finite element calculation. It was found that the introduction of TiC/C composites as transition layer had significantly decreased the stress shifts, with the largest shift to as low as 474 MPa. Additionally, extent of deformation was largely decreased. This is beneficial to avoiding formation of large cracks and preventing impurities from entering plasma environment.
Key words: titanium carbide coating; pyrocarbon; functionally graded materials; finite element calculation