The behavior of thick SiC gradient coatings on different graphites under high power electron beam irradiation, pulsed high energy laser impact, and HT-7 limiter plasma action was investigated. In the following tests at these facilities, the samples were examined using SIMS, EDAX, X-ray crystallography, profilometer and Auger spectroscopy. Thick SiC gradient coatings showed excellent durability under high heat flux and in real conditions of HT-7 limiter plasma irradiation. The primary results indicated that the use of multi-element doped graphite, GBST1308 (1%B4C, 2.5%Si, 7.5%Ti) with high thermal conductivity, as substrate will improve the durability of thick SiC gradient coatings significantly.