Adhesive strength of zinc alloy sprayed coatings on an annealed steel substrate after grit blasting was measured to understand an effect of work hardening of a substrate surface on adhesive strength between the substrate and the sprayed coatings. The annealed substrate was prepared by heat treatment in reduced atmosphere. The sprayed coatings were prepared by a wire flame spraying process. Degree of work hardening of the substrate was changed by changing blasting time. In the case without annealing, the hardness of the blasted substrate increases with increasing blasting time, and the adhesion increases with increasing hardness of the blasted substrate surface. In the case with annealing, the hardness of the blasted substrate is same as the hardness before blasting. Nevertheless, the adhesion is almost same as the case without annealing. There are no effects of work hardening of the steel substrate surface on the adhesion of the zinc alloy sprayed coatings.
The cold spray technique is solid coating process and has a superior feature compare with conventional spraying ones. For a solid process it has some problem, for example cold sprayed coating has a lot of dislocation in the coating. Although the coating has the same composition of bulk material, mechanical properties is different from bulk material. It is important that the dislocation in the coating is evaluated because the dislocation affects coating properties such as corrosion-resistant and so on. In this study Ni coating sprayed by low pressure type cold spray equipment was evaluated using electron backscattered diffraction (EBSD)analysis. Also the coating micro structure was observed by transmission electron microscopy (TEM). From TEM observation, a lot of sub grain could be observed in the coating. Although Kikuchi pattern could not observe in the coating completely. The area that could not observe Kikuchi pattern included a lot of sub grain. From results of EBSD analysis, misorientation increased in grain average misorientation (GAM) and kernel average misorientation (KAM) by heat treatment. It caused movement of dislocation from area that could not observe Kikuchi pattern. EBSD analysis is useful analysis for evaluate strain of cold spray coatings.