Erosion of boron carbide coating due to high pulse number transient heat loads

Abstract A boron carbide (B 4 C) coating, deposited on tungsten using the detonation spraying method, was tested under high pulse number transient heat loads expected during the ITER tokamak H-mode operation. The heat loads were relevant to those caused by edge localized modes (ELMs) and mitigated disruptions. The results showed that in the case of ELM-like heating expected in the first wall zone of the ITER tokamak, the coating is capable to withstand pulses before detachment from the substrate. In the case of thermal shocks with more intense heating by mitigated plasma disruptions or ELM-like heating in the divertor zone, the coating detached only after several pulses. The results of the work show that transient heat load is a serious factor limiting the use of B 4 C as a plasma-facing material. The use of such ceramic coatings requires the development of ELM and disruption mitigation systems, as well as in situ coating renewal methods.