Performance and damage behaviors of detonation sprayed W/Fe/steel coatings under transient high heat fluxes

The fabrication of high-quality W/steel joints for the blanket first wall presents a challenge in the field of nuclear fusion due to the inherent differences in properties between W and steel. In this study, detonation sprayed (DS) pure iron coatings were utilized as interlayers between DS W coatings and steel to improve the performance of the W/steel joints. The morphology of the DS W/DS Fe/steel coatings indicated that both DS W and DS Fe coating materials were of high quality. Axial tensile tests showed lower bonding strength of the DS W/DS Fe/steel substrate coating system than the DS W/steel coatings. However, the three-layer coating system exhibited much better performance in transient high heat flux (HHF) loading tests compared to the two-layer coating system. Moreover, the addition of DS Fe interlayers changed the failure mode of DS W/steel coatings from W coating detachment to partial melting of the W coating surface. The damage behaviors of the three-layer coating system under 45 MJ/m2 transient HHF were investigated to comprehend the stress-relieving effect of the DS Fe interlayers. These results unequivocally illustrate the possibility of employing DS W/DS Fe/steel coatings as a viable approach for the manufacturing and in-situ repairing of the blanket first wall.