Abstract

Self-fluxing nickel based materials are widely used as hard coating materials. HVOF process is promising to produce dense coating with high adhesion. In present study the effects of HVOF spray conditions, and WC-Co addition into self-fluxing nickel based material (NiCrBSi) and the introduction of HVOF WC-Co bond coat on the adhesion of HVOF NiCrBSi coatings are investigated. With regarding to NiCrBSi material, the spray conditions are optimized by orthogonal regression experimental design method with adhesive strength. The adhesive strength is estimated by tensile test. The results show that the adhesive strength of the NiCrBSi coating sprayed at the optimized conditions reaches to about 40MPa. It is found that the addition of WC-Co material through mechanical blending can improve the adhesion of HVOF NiCrBSi coating. The adhesive strength is increased with the increase in WC-Co content in the composite powder. The introduction of HVOF WC-Co bond coat between NiCrBSi coating and substrate can improve the adhesive strength. The multiply enhancing effect on the adhesive strength of HVOF nickel based coating is recognized by applying HVOF WC-Co bond coat to NiCrBSi-WC-Co composite coating.

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