Melting and heat transfer mechanism of powder by induction brazing coating

Induction brazing coating is an important method to improve the surface quality and the performances of materials. In this study, the carbon steel and ceramic were selected as basal plates to perform the induction brazing coating tests. Then the change law of powder and paste temperatures was studied systematically, and the mode and path of heat transfer were analyzed. The results showed that the coating materials could not be heated directly by induction brazing, and the heat source of the temperature rise of the brazing coating was almost all from the heat conduction of the steel matrix. During this process, intense heat transfer occurred at liquid-solid interface, promoting the melting and spreading of powder successively. When the substrate was replaced by carbon steel, which was conductive and heated by induction, the coating material could only be heated up by itself. Powder brazing coating particles presented free state, and were filled of gas between them. As a result, the heat of the matrix was difficult to conduct the upper part, and the powder was difficult to melt fully. However, the paste brazing coating added with adhesive could melt quickly in the induction process, and the binder played the roles of heat transfer, melting promoting and protection, and so on.