Study On Corrosion Resistance Of Low Pressure Cold Sprayed Copper Matrix Composite Coatings Alloy

Corrosion is one of the main forms of mechanical damage and failure.The use of low pressure cold spray technology to repair damaged workpieces can extend the life of the workpiece.Copper has a very high thermodynamic stability.If used as a single repair powder,it can form an electrochemical effect with most substrates in a corrosive environment,thus accelerating the corrosion of the substrate.Therefore,the addition of sacrificial corrosion-resistant anode powder as a repair layer in the copper powder not only avoids corrosion of the substrate,but also improves the corrosion resistance of the repair layer.In this paper,cold-spraying technology is used to repair damaged chrome-plated rods with copper-zinc and copper-aluminum powders.Static immersion and copper accelerated acetate spray test（CASS）are applied to the coating samples and coatings with chrome plating samples.Corrosion resistance was studied.The main findings are as follows:Copper-zinc and copper-aluminum coatings were prepared by cold spraying.The porosity of the coatings decreased first and then increased with the increase of zinc and aluminum content.When the ratio of copper to zinc was 6:4,the ratio of copper to aluminum was 7:3,the corresponding coating has the highest density.Static corrosion experiments show that when the original powder does not contain zinc,the corresponding coating samples have better corrosion resistance,which is attributed to the higher thermodynamic stability of copper;the coating is chrome-plated under this ratio.The surface of the chrome plating layer in the sample showed severe corrosion pits due to electrochemical corrosion.With the increase of the content of zinc and aluminum in the original powder,the corrosion resistance of the corresponding coating samples and the coating and chrome plating samples of the two powder ratios increased first and then decreased;Under the powder ratio,the corrosion resistance of the corresponding coating sample is better than that of the coating plus chrome plating sample.When the ratio of copper to zinc is 6:4 and the ratio of copper to aluminum is 7:3,the corresponding coating and coating The chrome-plated sample has the best corrosion resistance.CASS experiments show that when the ratio of copper to zinc is 6:4and the ratio of copper to aluminum is 7:3,the corrosion resistance of the corresponding coating samples and coatings plus chrome plating samples meets the corrosion-resistant six-level standard.The excellent corrosion resistance of the coated samples is attributed to the barrier effect of the bottom porosity of the coating on the corrosive medium and the sealing effect of the corrosion products Zn（OH）₃ and Al（OH）₃.The presence of zinc and aluminum in the coating and chrome plating samples can alleviate the corrosion of the chrome plating layer to some extent,mainly because of the preferential corrosion of zinc and aluminum in the coating,thus greatly reducing the corrosion of the chrome plating layer.When the ratio of copper to aluminum is 7:3,the heat treatment experiments of the corresponding coating sample and the coating with chrome plating show that the copper and aluminum in the coating and the chrome plating sample are coated with the increase of the heat treatment temperature.The element has obvious diffusion phenomenon;due to the high melting point and low diffusivity of chromium in the chrome plating layer,the diffusion of chromium is not obvious.When the heat treatment temperature is 450℃,the coating structure is the most dense,and the coating is most closely combined with the chrome plating layer.The static corrosion and polarization curves show that the corrosion resistance of the coating and the chrome-plated coating increases first and then increases with the increase of the heat treatment temperature.When the heat treatment temperature is 450℃,the solution and coating The corrosion contact points in the layer are minimal;therefore,the high density of the coating effectively prevents the infiltration of corrosive media,thereby providing long-lasting effective protection for the substrate.