Thick pure tungsten coatings were deposited on molybdenum and copper substrate by vacuum plasma spray for different purpose. The microstructures of tungsten coatings were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of preheating temperature of the substrate and introduction of gradient bond layer on the adhesive strength of the coating was investigated. High heat load was tested by high power electron beam bombardment only for tungsten coating on copper. All the results show that the properties of tungsten coating were strongly influenced by different processes, and the density of the coatings is close to 95% of theory density.

For the coating of divertor wings, which in an adapted form may also be suitable for divertor targets, tungsten coatings were developed and optimized with respect to erosion and adhesion behaviour and tested in the Jülich JUDITH facility as well as in the St. Petersburg TSEFEY facility. For the improvement of adhesion, interlayers were developed and used for the coating of mock-ups. In order to achieve a further improvement in adhesion and thus better heat removal, structures were developed for the substrate surfaces. Substrate materials are copper according to DIN 1787 and the Elmedur X copper-chromium-zircon alloy. Differently produced tungsten coatings on mock-up substrates were loaded until failure by means of an electron beam. The area-related thermal loads introduced until failure were measured and correlated with the production parameters.

Plasma sprayed tungsten coatings are considered as potential candidates for materials in contact with the plasma in future fusion reactors. In this work, the thermal shock resistance of these coatings is studied to determine which of five changed deposition parameters most influences the coating's performance. The thermal shocks were generated with a pulsed electron beam gun. The pulse duration was 0.2 and 0.5 s and the absorbed power density 60 MW/m 2 . Two series of samples were analyzed. One was plasma sprayed at atmospheric pressure (AP) and the other at low pressure (LP). The LP coatings were deposited on a molybdenum alloy (TZM). AP coatings were deposited on molybdenum and on water cooled copper coupons for fatigue tests. The porosity seems to be a positive factor for thermal shock resistance. The thickness of the coatings and the spraying atmosphere were found to strongly influence the thermal shock resistance. In the case of the fatigue test, some coatings withstood up to 1000 shocks of 0.5 s duration.

High-Z materials such as tungsten are currently considered more suitable for the inner coatings of fusion devices than low-Z materials. The VPS parameters are being optimized for different tungsten powders with respect to uniform pore distribution and distribution of unmelted particles in the coating. High process reliability is aimed at in coating production. Copper is used as the substrate material. The spray efficiencies, coating porosities and unmelted particles in the coatings are being examined and the microstructures evaluated. Spraying parameters are determined for two different powder fractions leading to relative densities ≥ 90 % of the theoretical density.