In nuclear fusion devices plasma-facino, materials (PFM) have to sustain extreme environments. The first wall of fusion experiments or future power plants is loaded with thermal radiation and high-energy particles, eroding the wall material. In current I experiments low-Z-materials such as graphite and carbon composites are preferred PFM, but basic disadvantages are the high erosion rate and accumulation of hydrogen. For the new WENDELSTEIN 7-X fusion experiment (W7-X), now under construction at Greifswald (Germany), 70 m(2) of water-cooled wall protection will be coated with B4C layers by vacuum plasma spraying (VPS). VPS provides the required high purity of coating materials and is an effective industrial method. The thermal expansion mismatch of the ceramic B4C coating and stainless-steel (SS) substrate and, the high processing temperature require an interlayer to reduce residual stress. An interlayer made of SS mixed with B4C has been successfully developed. An alternative high-Z PFM with very low erosion is tungsten, which shows good plasma-physical and thermo-mechanical behaviour in fusion experiments. The VPS-B4C technology developed is transferable to coatings of W on SS. Tungsten will possibly be employed as a protective material for the first wall in the next fusion experiment, ITER. In co-operation with industrial partners, the Materials Research Department of Institut fur Plasmaphysik (IPP) are developing and characterising these layers. Coated components are being extensively thermally tested with heat loads of up to 200 kW/m(2) (B4C) and 2.5 MW/m(2) (W), respectively. Micrographs are being studied in structure and porosity, energy dispersed X-ray analysis (EDX) and ion beam Rutherford Back Scattering (RBS) are being used to examine the impurities. The Young's modulus, residual stresses and thermal conductivity are being analysed by experimental methods as well as deuterium retention depend on temperatures of about up to 800 K. It is shown that the VPS-B4C coatings developed are suitable for W7-X experiment and VPS-W layers could be applied in ITER experiment.
