Ti coatings for anti-corrosion coating were prepared via cold spray process, and their microstructures, adhesion morphology of feedstock powders, and influence of post treatment on mechanical properties were evaluated. The Ti coatings were fabricated using Ti powder with the size of -45um onto mild steel substrate with N2 carrier gas, and heat treated at 1093K and compressed with the force range of 98-1176 MPa. Porosity of the cold sprayed coating is 5.4 %. The coating adheres to the substrate metallurgically, however, pores with the size of approximately 10um exist at coating/substrate boundary. After the heat treatment, the porosity decreases to 4.1 %, and bond strength of the coating increases from 13 MPa to more than 70 MPa. Density of the coating enhances with increasing the compressive force in the both case of before and after the heat treatment. However, in the case of after heat treatment, the bond strength decreases with increasing the compressive force due to occurring of cracks at the coating/substrate boundary, and it is considered that the starting points of the cracking are the pores at the boundary. Therefore, it is expected that prevention of the pores might be effective for improvement of the bond strength of the compressed coatings.

抄録全体を表示

Co-Cr-Mo alloy has superior material properties such as corrosion and wear resistance and so on. Therefore the alloy is applied to biomaterial. Most studies, however. have not focused on the thermal spray using Co-Cr-Mo alloy. In this study gas atomized Co-Cr-Mo powder was sprayed on SS400 substrate using cold spray, HVOF and plasma spray methods. Kinetic Metallization System manufactured by Inovati, USA was used as cold spray equipment. Plasma spray was carried out in various spray conditions. Their coating micro structures were observed by FE-EPMA (JXA-8530F manufactured by JEOL) and micro vickers hardness were measured. Cold sprayed coating and used powder were observed electron backscatter diffraction pattern (EBSD). Also heat treated ones were observed, too.HVOF and plasma sprayed coatings consist oxide in their coatings. Cold sprayed coating was dense coating without oxide. Micro Vickers hardness of coating sprayed by cold spray was higher than other sprayed coatings. Micro Vickers hardness of coatings sprayed by plasma spray tend to increase with increasing plasma power. It was due to quantity of oxide in coating. On the other hand much deformation exists in cold sprayed coating from EBSD analysis. Used powder was γ phase and cold sprayed coating was almost ε phase. Stress - induction phase transformation occurs in cold spray process. It is clear that the high hardness is due to deformations in the coating.

抄録全体を表示