PLASMA-SPRAYED BORON-CARBIDE COATINGS FOR 1ST-WALL PROTECTION

Plasma-sprayed boron carbide coatings have been manufactured by differ ent suppliers onto substrates of type 316L stainless steel. The coatin g thickness ranges from 0.3 to 2.0 mm. The larger thicknesses could on ly be achieved by application of an adaptive or gradient bond-layer be tween substrate and the boron carbide top coating. Measurements of the thermal diffusivity of coating materials are reported. Several high h eat flux facilities have been used to study the thermal shock and eros ion behaviour of the coated samples. A supporting numerical analysis o f the thermal behaviour of the coating under normal and off-normal hea t loads is presented, focussing on the differences between electron be am and laser beam tests due to volumetric energy deposition. Some aspe cts of the applicability of plasma sprayed B4C coatings for first-wall protection in a next step device are discussed.