| With the continuous development of science and technology,copper alloys play an important role in seawater corrosion resistance,improving the mechanical properties of materials and preventing the adhesion of marine microorganisms,and are widely used in ship engineering and marine engineering construction.Copper alloy surface generation of the dense insoluble film is the main reason for the significant decline in the anti-fouling performance of the copper alloy.Only when the copper alloy surface corrosion products loose,containing cracks,the surface corrosion products can be in a certain flow rate of shear force under the action of flaking so as to achieve the self-polishing effect and achieve the purpose of the long-term prevention of sea life adhesion.In this paper,laser cladding layers of Cu-Mn alloys with different Mn contents were prepared with Mn contents of 3 wt.%(Mn3Cu),5 wt.%(Mn5Cu)and 7 wt.%(Mn7Cu),Mn3Cu,Mn5Cu,and Mn7Cu below represent the laser cladding layers of Cu-Mn alloys with three Mn contents.Analysis of the microstructure,phase composition,Vickers hardness,and mechanical properties of the clad layer in room temperature tensile and compression tests.The corrosion resistance of the melt-clad samples was studied using electrochemical workstation and salt spray corrosion tests.The changes of corrosion product morphology and composition at different Mn contents and corrosion times of the samples were studied using electrolytic accelerated corrosion and immersion corrosion,and the copper ion exudation rate was tested.The Cu-Mn alloy cladding layer is composed of two elements,Cu and Mn,in an infinite solid solution.Microhardness analysis showed that the hardness increased with the increase of Mn content.The results of room temperature tensile and compressive tests show that with the increase of Mn content,the tensile and compressive property indexes increase faster and better in strength,toughness and compressive resistance.The fracture morphology shows that the higher the Mn content in the molten cladding layer,the more tough nests and the better plasticity.In the electrochemical test,the results of open circuit potential and polarization curves show that Mn7Cu has a greater tendency to corrode,and the impedance spectrum shows that the radius of capacitive arc decreases with increasing Mn content,and Mn7Cu has a lower impedance value,a stronger ion passage ability,and a higher copper ion release rate.In the salt spray corrosion test,with the increase of Mn content,the corrosion of Cu-Mn alloy melt cladding layer deepens,and the main corrosion product composition on the surface is a mixture of Cu-Mn solid solution,Cu2Cl(OH)3,Cu2O and MnO2,and the average mass loss of Mn7Cu is the largest.After accelerated corrosion by electrolysis,in the same corrosion time,the corrosion products generated by Cu-Mn alloy samples with high Mn content are looser and easier to peel off than those with low Mn content,which accelerates the charge transfer rate and is more beneficial to promote the release of copper ions;under the same conditions of Mn content,the longer the corrosion time,the increase in the number of defects such as crack holes,seawater enters through the cracks to promote the continuation of the corrosion reaction,which in turn promotes the shedding of corrosion products and increases the release rate of Cu2+.The immersion corrosion results show that the corrosion products on the surface of the melt-clad layer samples after immersion corrosion in artificial seawater are bumpy,loose and porous with cracks.At the same time,there is a local range of shedding.The higher the Mn content and the longer the corrosion time,the more serious the corrosion morphology and the easier the outer corrosion products are to be shed.The easier it is for the copper ions in the inner layer to seep through the cracks and improve the release rate of copper ions.The copper ion exudation test results showed that the copper ion release rate of the samples increased with the Mn content,and all three melt-clad samples could meet the anti-fouling standard of inhibiting the adhesion of marine microorganisms. |
