Manufacture of vacuum plasma spraying tungsten with homogenous texture on reduced activation ferritic steel at about 873K

The key to improving the heat load of vacuum plasma sprayed tungsten coatings on low activation ferritic steel maintained at low temperatures is elimination of stratified low-density layers with many large pores, in which thermal cracks propagate preferentially. The low-density layers are formed owing to the deposition of large solidified tungsten particles, which remain mainly at the periphery of the spray stream. In this study, by shading this periphery, partially homogeneous tungsten coatings without large pores were successfully obtained. The coatings are expected to show good heat load, which is feasible for nuclear fusion applications.