Study On Structure And Property Of Nickel Matrix Nano Composite Coatings Prepared With Electro-brush Plating

In this paper, the composite electrolyte with ZrO₂nanoparticles andY₂O₃nanoparticles were respectively prepared on the basis of fast nickelelectrolyte. Ni/ZrO₂nanoparticle composite coatings and Ni/Y₂O₃nanoparticle composite coatings were prepared with electro-brush platingon substrate of2Cr13stainless steel.The effect of nanoparticle content in solution on the microstructure andproperties of coating were researched, including the observation of surfacemorphology and cross-sectional microstructure of coatings, analysis ofstructure and component, measurement of microhardness, the effect of heattreating temperatures on hardness of coatings, bonding strength betweencoating and substrate, porosity, corrosion resistance, wear resistance andhigh temperature oxidation resistance measurement and analysis. And themicrostructure and properties of nanoparticle composite coatings werecompared and analyzed with that of fast nickel coating.The study results show that the bonding interface between the coating and substrate（2Cr13） is combined closely with concave convex structureand the coating spalling has not occurred. Nano particle content in thesolution has obvious effects on microstructure and properties of compositecoatings. In some scope of concentrations, the grain size of compositecoating becomes fine and even as the increase of the nano particle contentin plating solution, meanwhile the microhardness of coating is constantlyimproved. The microhardness of coating is gradually decreased with theincrease of nano particle content in plating solution when the contentreached a certain level, and the grain size of coatings becomes coarsening.The results of heat treatment test show that the hardness of fast nickelcoating, Ni/ZrO₂nano composite coating and Ni/Y₂O₃nano compositecoating reaches the maximum value around250℃. The microhardness ofcomposite coatings, whether being plated or heat-treated, is both higherthan that of fast nickel coating.The anodic polarization curves of coatings in3.5％NaCl aqueoussolution show that two kind of composite coatings both have a smallercorrosion current and a higher free-corrosion potential and better corrosion resistance than that of fast nickel coating, in which the corrosion resistanceof Ni/Y₂O₃nano composite coating is best. The friction and wear testindicates that the friction coefficients of both composite coatings aresignificantly lower than that of fast nickel coating. The plowed wear effecton the wearing surface of both composite coatings is weakened with thenanoparticles’ dispersive distribution in the coatings, the adhesion wearphenomenon is also greatly reduced. High-temperature oxidation test in airat800℃shows that the weight-increased rate of fast nickel coating isobviously higher than both nano composite coatings, the grain size ofcomposite coatings after oxidation are still smaller and evenly than that offast nickel coating. The XRD analysis shows that oxidation degree ofcomposite coatings is lighter, and there are a lot of nickel phases.