Tungsten coatings deposited on CFC tiles by the combined magnetron sputtering and ion implantation technique

Combined magnetron sputtering and ion implantation (CMSII) is a deposition technique involving simultaneous magnetron sputtering and high energy ion bombardment of the coating during its growth. A high voltage pulse discharge (U=40 kV, τ=20 μs, f=25 Hz) is superposed over the magnetron deposition and in this way, positive ions are accelerated to the components to be coated, bombarding initially the substrate and then the coating itself. In the framework of the ITER-like wall project this method was applied to produce nanostructured W coatings on the carbon fibre composite (CFC) substrate. These coatings have been characterized in terms of adhesion, thickness, structure and resistance to high thermal loads (up to 23.5 MW m^-2). Based on the results of these tests, which are presented in this paper, CMSII technology was selected for coating about 1100 tiles with a 10 μm tungsten layer for the JET first wall and divertor.