Cold Sprayed Tungsten Armor for Tokamak First Wall

Abstract

Harnessing nuclear fusion is a challenging task, in particular because of the demands put on the used materials. In tokamaks, future energy sources, the inner-most chambers are to be coated with dense coatings of W, or W-Cr-based alloys. So far, the attempts for such coatings formation by other methods failed due to oxidation, high porosity, insufficient adhesion, high specific surface, or even insufficient thickness below 10 mu m. Cold spraying seems a promising technology for the task. In our study, we demonstrate the first successful fabrication of thick pure W coatings. W-Cr and W-Cr-Ti coatings were further prepared without oxidation of the metals. All coatings exhibited high hardness levels, good interface quality with three tested substrates and, importantly, a promising potential for formation of stable Cr2WOx phases.Harnessing nuclear fusion is a challenging task, in particular because of the demands put on the used materials. In tokamaks, future energy sources, the inner-most chambers are to be coated with dense coatings of W, or W-Cr-based alloys. So far, the attempts for such coatings formation by other methods failed due to oxidation, high porosity, insufficient adhesion, high specific surface, or even insufficient thickness below 10 mu m. Cold spraying seems a promising technology for the task. In our study, we demonstrate the first successful fabrication of thick pure W coatings. W-Cr and W-Cr-Ti coatings were further prepared without oxidation of the metals. All coatings exhibited high hardness levels, good interface quality with three tested substrates and, importantly, a promising potential for formation of stable Cr2WOx phases.