Research On The Process And Properties Of Ni-Mn-SiC Composite Coatings By Jet-electrodeposition

Ni-Mn alloy coating has good mechanical properties and corrosion resistance,so it has been widely concerned and studied.Nano ?-SiC nanoparticles belong to cubic crystal system,which have good creep resistance,fracture resistance,and high hardness and chemical stability.The nano ?-SiC nanoparticles are placed in acidic Ni-Mn plating solution to prepare Ni-Mn-SiC nano composite coating by spray electrodeposition,which can effectively improve the microhardness,wear resistance and corrosion resistance of Ni-Mn alloy coating,applying it to the strengthening and repairing of parts can effectively strengthen the service performance of parts and greatly extend their service life.In this paper,Ni-Mn-SiC nanocomposite coating was prepared by spray electrodeposition equipment.The microhardness,surface roughness,wear resistance,corrosion resistance and other properties of the composite coating were tested.The effects of process parameters such as voltage,pulse frequency,duty cycle and feed rate on the coating performance were studied,in order to obtain the best Ni-Mn-SiC nanocomposite coating.The specific research contents are as follows:(1)The basic theories of spray electrodeposition and composite electrodeposition are introduced.On this basis,the effects of concentration of trisodium citrate,saccharin and ?SiC nanoparticles on the surface morphology,cross-section morphology,deposition rate,phase structure,microhardness and wear resistance of the coating are studied.The optimal concentration of trisodium citrate is determined as 40g/L,saccharin 1g/L and ?-SiC 4g/L,respectively.(2)The experimental design and data analysis were carried out by using the experimental data analysis software JMP.The effects of voltage,pulse frequency,duty cycle and feed speed on the surface roughness,microhardness and wear resistance of the composite coating during the spray electrodeposition were studied.The optimal process parameter combination was obtained:voltage 4.2V,pulse frequency 3.2kHz,pulse duty cycle 64%,feed speed 135mm/s,under the condition,the surface roughness of the coating is 0.484 ?m,the microhardness is 615.5HV0.05,and the wear mark width is 418.1?m.(3)The Ni-Mn-SiC composite coating was characterized,the results show that the average surface roughness of the composite coating is 0.494?m,the average surface microhardness is 618.3HV0.05,and the average wear mark width is 424.6 ?m.Compared with the predicted values,the errors of surface roughness,average microhardness and wear mark width are 2.1%,0.5%and 1.4%respectively,which are close to the predicted values,it shows that the accuracy of each prediction model is high.(4)The properties of the matrix of 45 steel,Ni-Mn alloy coating and Ni-Mn-SiC composite coating were compared,it is found that the bonding strength of Ni-Mn-SiC composite coating and Ni-Mn alloy coating are 52.3N and 48.8N respectively.The microhardness test shows that the Ni-Mn-SiC composite coating and Ni-Mn alloy coating are 117%and 63%higher than that of 45 steel samples respectively,and the wear resistance is also improved.In the corrosion resistance test,the corrosion rate of Ni-Mn-SiC composite coating and Ni-Mn alloy coating is 190.8%and 51.4%lower than that of 45 steel samples respectively,and the charge transfer resistance is 170.7%and 395.0%higher.The results show that both Ni-Mn alloy coating and Ni-Mn-SiC composite coating can effectively strengthen the mechanical properties and corrosion resistance of 45 steel,among which NiMn-SiC composite coating is the best.