Plasma-sprayed boron carbide coatings for first-wall protection

Plasma-sprayed boron carbide coatings have been manufactured by different suppliers onto substrates of type 316L stainless steel. The coating thickness ranges from 0.3 to 2.0 mm. The larger thicknesses could only be achieved by application of an adaptive or gradient bond-layer between substrate and the boron carbide top coating. Measurements of the thermal diffusivity of coating materials are reported. Several high heat flux facilities have been used to study the thermal shock and erosion behaviour of the coated samples. A supporting numerical analysis of the thermal behaviour of the coating under normal and off-normal heat loads is presented, focussing on the differences between electron beam and laser beam tests due to volumetric energy deposition. Some aspects of the applicability of plasma sprayed B 4C coatings for first-wall protection in a next step device are discussed.