A method of surface hardening, coating deposition and surface alloying based on electrical resistive heating localized at the surface of a metal substrate has been developed. Localization of resistive hearing was obtained by passing electric current through the contact between a moving roller and the substrate. The small size of the contact imposed a severe constriction on the electric current causing intense resistive heating close ro the contact. Simultaneous motion of the roller and substrate provided surface coverage by the heating process. Tests with steel on steel showed that this technique can generate a surface layer with a martensitic or quenched microstructure, whilst a lest with zinc on copper revealed that surface alloyed layer of copper and zinc can be generated. Tests where tile roller has a lower melting point than the substrate, e.g. tests with zinc on steel substrates, revealed that a strongly adhering coating can be deposited by the roller.
Stachowiak, G., & Batchelor, A. W. (1996). Surface Hardening and Deposition of Coatings on Metals by a Mobile Source of Localized Electrical Resistive Heating. Journal of Materials Processing Technology, 57, 288-297. https://doi.org/10.1016/0924-0136(95)02070-5