Interface reaction between nickel-base self-fluxing alloy coating and steel substrate

The interface reaction between a nickel-base, self-fluxing alloy coating an d a steel substrate has been investigated to examine the formation of "pore s," which are observed along the interface of used boiler tubes. It,vas fou nd that lumpy precipitates form along the interface instead of pores after heating at high temperatures and that the precipitates are of Fe2B boride, The adhesion strength of the coating is not decreased by the formation of F e2B precipitates along the interface because of the increase of the adhesio n due to interdiffusion.