Adhesive and Cohesive Strength of Thick LPPS W Coating on CuCrZr Substrate

Advanced materials are the crucial factors determining the successful application of future nuclear fusion energy. Plasma facing materials (PFMs) are one of the most important armor materials in nuclear fusion experiment devices for direct facing with the extremely high thermal load, strong thermal shock and heavy irradiation of high energy particles. W coated CuCrZr substrate has been considered as one of the candidates to the armor material due to its high melting point, chemical stability and good thermal conductivity. However it was really a difficult job to obtain the high strength thick W coating because of the great difference of CTE between W and CuCrZr substrate.

In this paper, the surface roughening process was optimized via grit blasting treatment and mechanical treatment in order to improve the adhesive strength of W coating. The various graded W/Cu layers were deposited as the bond layer via Low Pressure Plasma Spraying (LPPS) on the CuCrZr substrate with different surface roughness, and then thick LPPS W coating over 1.5 mm was prepared as the top layer. The effect of surface roughness and bond layer on the adhesive strength for thick W coating on CuCrZr substrate was discussed according to the standard of ASTM C633. Finally the cohesive strength for as sprayed thick W coating was also evaluated.