Effect of physical/chemical removal of NiCoCrAlYHf coatings on the surface organisation of DD6 alloy

Abstract:

In this paper, NiCoCrAlYHf (HY5) coating was deposited on the surface of the second-generation nickel-based DD6 single-crystal high-temperature alloy by vacuum arc plating process, and the surface coating was removed by physical blowing sand method and chemical solution immersion method, respectively, for a comparative study of the effect of removal of the coating by the two and the degree of influence on the matrix alloy. The results show that: the thickness of the coating is about 20 μm, which is mainly composed of γ" and β phases; no coating remains on the surface of the substrate after treatment by the physical method or chemical method, and the original coatings are completely removed. Under the cutting action of the sand blowing particles in the physical method, the surface of the matrix alloy presents a concave-convex morphology on the macro level, and the deformation layer is generated by the deformation along the <110> orientation on the micro level; the physical method destroys the integrity of the surface of the matrix alloy, which is more damaging to the matrix. The chemical treatment only produces a γ" phase damage layer in the local area, which is less damaging to the substrate.