Study On Corrosion And Wear Resistance Of Ni/GO Coating On 2024-t6 Aluminum Alloy

Aluminum alloy drill pipe has higher strength and lower energy consumption,therefore,it is suitable for complex working conditions and has good application prospect.However,in engineering application,the aluminum alloy drill pipe has poor corrosion and wear resistance,which often leads to the failure of the aluminum alloy drill pipe,especially in salty mud.This limits the development of drilling engineering.Graphene oxide has good mechanical properties,corrosion resistance and wear resistance.In this paperGrapheneoxide(GO)was successfully prepared by Hummer's GO preparation method,and Ni/GO coating was prepared on the 2024-t6 aluminum alloy surface.Electrochemical corrosion tests and long-time immersion corrosion tests were carried out in simulated salty mud,and corrosive wear resistance of the samples in simulated salty mud was studied by using MS-T3001 friction wear testing instrument.Optical microscope,scanning electron microscope,x-ray diffractometer were used for the observation of morphology and chemical composition of the coatings.The corrosion and wear mechanism of the aluminum alloy drill pipe was discussed.The main points are as follows.(1)The results of infrared spectroscopic analysis,SEM morphology and XRD phase tests of GO showed that the prepared GO was of good laminated structure.The optimum current,voltage,temperature and time of electroplated nickel and Ni/GO composite coating of 2024-t6 aluminum alloy were determined.The morphology and phase of the coating were characterized by SEM,EDS and XRD respectively.The results showed that the grains were homogenous and dense on the surface of prepared coating and the characteristic peak of Ni/C element was obvious.(2)Through comparative analysis of two kinds of coatings by SEM and EDS,it was obviously observed that nickel metal evenly grew in aggregation form on the sample surface,and graphene was unevenly absorbed on the Ni-coated surface.The phase composition of two kinds of coatings was carried out through XRD to verify the existence of Ni and Cu diffraction peaks in nickel plated coating of 2024-t6 aluminum alloy and Ni/GO composite coating.(3)Electrochemical corrosion experiments showed that the electrochemical impedance spectrum of the Ni/GO coating was the largest,and the corrosion current density was the smallest.In addition,the microstructure after electrochemical corrosion showed that the corrosion pits and corrosion degree of the Ni/GO coating were the smallest.After 30 days of immersion corrosion,metallographic observation showed that Ni/GO has only partial curvilinear corrosion,while Ni coating and matrix were corroded obviously,further confirming that Ni/GO coating had the best corrosion resistance.(4)Corrosive wear test results show that the friction coefficient of Ni/GO composite coating is the smallest.The composite coating had the shallowest wear debris,and the aluminum alloy specimen had the deepest wear mark.The composite coating had the smallest wear volume.The SEM morphology of wear debris showed that the wear spots of composite coating samples under the same load were significantly smaller than that of nickel coating and aluminum matrix,indicating that the wear was the lightest.The results show that the composite coating can greatly improve the wear resistance of aluminum alloy matrix.Based on the surface characteristics,corrosion and wear properties of Ni/GO coating,the corrosive wear mechanism model of Ni/GO coating was established.