Vacuum plasma-sprayed tungsten on EUROFER and 316L:: Results of characterisation and thermal loading tests

Vacuum plasma-spraying (VPS) can be used for the industrial deposition of thick W coatings on actively water-cooled components made of low activation steel or stainless steel. Mock-ups made of martensitic steels, EUROFER and F82H, as well as steel 316L, were coated with 2 mm thick W-VPS layers. The coated materials are candidates for first wall components (ITER and DEMO) receiving moderate heat load of up to 1 MW/M(2). Mixed tungsten/steel interlayers were applied to reduce the residual and thermal stresses at the substrate-coating interface and to improve the adhesion of the coating. The advantage of this mixed interlayer is that no further (high activation) materials have to be introduced to improve coating adhesion. The characterisation of the W-VPS layers includes the evaluation of the coating microstructure, the measurement of physical and mechanical properties and the metallographical examination before and after heat load tests. Heat load tests with steady state operation up to 2.5 MW/M2 and cycling heat loads of 2 MW/m(2), were successfully completed. They confirm the thermornechanical suitability of industrially manufactured W-VPS coatings for plasma facing first wall components made of steel. (c) 2005 Elsevier B.V. All rights reserved.