Optimization of an electron beam remelting of HVOF sprayed alloys and carbides

Due to the lamella structure of the coating and the lack of metallurgical bonding, thermal sprayed coatings may have disadvantages such as low coating cohesive strength and low interface strength between the substrate and coating. It was considered that the electron beam remelting process is one of the most convenient processes to reduce or remove these disadvantages. The optimization of electron beam remelting process parameters and the evaluation of this process were investigated. Not only electron beam conditions, but also the thickness of copper substrate and electroplated Ni affect the penetration depth and the remelted width at the interface. Also, in order to reduce the number of pores and the unevenness of the surface morphology, it was found that relatively low fusing speed and homogeneous heating are preferable. Moreover, because the metallurgical bonding could dominate the interfacial strength, the interfacial shear strength is independent of the coating hardness. Thus, it is successful to deposit coatings, Stellite 6, Ni based self-fused alloy 4 and WC-12Co with an adhesion strength value of approximately 350 MPa. (C) 2002 Elsevier Science B.V All rights reserved.