Experimental Study On Marine Corrosion Resistance Of Bionic Copper Base Surface

In marine environment,copper and copper alloys face serious corrosion problems due to the presence of a large number of halide corrosive media.Inspired by the special structure of peacock feathers in nature,this paper constructed biomimetic feather-like micro-nano structures on the surface of copper alloy by laser etching and laser-brush plating.Scanning electron microscopy showed that the surface morphology of the sample changed regularly under different machining parameters,which also showed the change of corrosion resistance.Salt spray corrosion tests showed that the laser-etched and laser-brush plating specimens exhibit better corrosion resistance than the polished control group in the initial corrosion,and the polished specimens exhibited general corrosion.In the late stage of salt spray corrosion,the laser-etched samples showed more serious local corrosion,and the laser-brush plating samples also appeared local coating dissolution,but the overall corrosion area was small.Nickel coating can play an electrochemical protection role on the copper alloy substrate.The morphology observation and composition analysis of the corrosion products showed that the corrosion products of the polishing samples were distributed uniformly,and there were cracks in the corrosion product layer of the three samples,and the product layer cannot prevent the further erosion of the corrosive media.The polishing samples and laser-etched samples showed obvious decomposition corrosion,while the laser-brush plating samples had almost no decomposition corrosion,indicating that the nickel coating had an inhibitory effect on the decomposition corrosion of the copper alloy.Electrochemical analysis of specimens before and after the salt fog corrosion showed that the laser etching surface had high electrochemical impedance and the impedance value of the laser-brush plating surface was similar to the polishing sample.After salt-fog corrosion test,the impedance of the polishing sample values fell rapidly,and corrosion potential fell significantly,and corrosion potential of laser etching specimen and laser-brush plating specimen are also decline to varying degrees,but the overall corrosion current density is low,further proved that the bionic structure with air cushion layer enhanced the corrosion resistance.Laser-brush plating treatment can protect metal from corrosion for a long time.The research process and results of this paper will provide some reference value for the Marine corrosion resistance research of copper alloy.