The behavior of coatings and SiCf/SiC composites under thermal shock

The behavior of various coatings and SiCf/SiC composites under thermal shoc k is described in this paper. The erosion of the SiCf/SiC composites and Ti C + TiN coatings under thermal shock is less than that of WC, TiN, TiC and B4C coatings. The surface of multi-are ion coating (MAIC) TiC, TiN and TiC + TiN coatings under thermal shock has cracks due to the interface between coating and substrate. The ion beam enhanced deposition (IBED) TIC coatings and plasma spraying coating (PSC) B4C and WC coatings under thermal shock do not have cracks. It seems that these coatings approximate to three-dimen sional heat transfer. The surface of 2D Hi-Nicalon SiCf/SiC composites unde r thermal shock indicates sublimation and trace melting. The melting region is only presented in the matrix, and the fiber retained its integrity. Thi s means that the matrix has poor thermal diffusivity, especially for interf ace damage between fiber and matrix. (C) 2000 Elsevier Science B.V. All rig hts reserved.