Jet-electrodeposition Of Ni-P-Mn-SiC Composite Coating And Its Process And Properties

As a new special processing method,jet electrodeposition technology(also known as electrospray plating)has the advantages of high deposition rate,compact plating and excellent plating performance compared with traditional electrodeposition.Ni-P alloy prepared by electrodeposition has excellent wear resistance,hardness and good corrosion resistance.Plating Ni-P alloy coating on the surface of parts can improve the service life and reliability of parts and improve machine equipment.The performance and quality have high economic and practical value.When Mn2+ with better corrosion resistance is added to the Ni2+-containing plating solution,a Ni-Mn alloy plating layer with better performance can be obtained,and the corrosion resistance of the plating layer can be remarkably enhanced.SiC nanoparticles have the characteristics of stable chemical properties,good wear resistance and high hardness.As the second co-deposited particles are deposited in the alloy coating,the wear resistance,corrosion resistance and surface hardness of the coating can be significantly improved.In this paper,the laboratory experiments were carried out by using the spray electrodeposition device built by the laboratory.The Ni-P-Mn-SiC composite plating process and its properties were studied on the surface of 45#steel substrate.The details are as follows:(1)Based on the preliminary test,the test factors and the scope of the factors were determined.Single factor tests were carried out on the pitch,voltage,pulse frequency and duty cycle respectively to study the effects of various factors on the surface hardness,coating thickness,wear scar width and surface roughness of the coating.Combined with the surface morphology analysis test results,when the pitch was 1.6mm,the voltage was 26V,the pulse frequency was 2kHz,and the duty ratio was 80%,the corresponding coating performance parameters were better.(2)Based on the custom experimental design of JMP software,a four-factor and three-level orthogonal test on pitch,voltage,pulse frequency and duty ratio was custom designed on the basis of single factor test.The interaction law of each factor was analyzed by 3D surface map and contour map,and the response regression equations of surface hardness,coating thickness,wear scar width and surface roughness reaction coating performance parameters were obtained.The maximum intent to solve the four equations is to obtain the optimal process parameters and the predicted values of the optimal coating performance parameters:voltage 26V,spacing 1.9mm,pulse frequency 1.8kHz,and duty cycle 87%.Corresponding coating performance parameters were:surface hardness 560.47HV,coating thickness 7.97?m,surface roughness 0.0183?m,wear scar width 438.68?m.The influence of various factors on the coating performance was found,and the duty ratio>voltage>spacing>pulse frequency.Later,the experimental results verified that the prediction results differed from the actual results by less than 3%,indicating that the regression equation was authentic and can be used to predict the Ni-P-Mn coating.(3)Based on the orthogonal experimental study,the Ni-P-Mn coating with the best performance parameters was added,and SiC nanoparticles with diameters of 20nm,40nm and 60nm were added.The effects of SiC nanoparticles with different diameters on the properties of Ni-P-Mn-SiC composite coatings were investigated.It was found that the addition of SiC nanoparticles to the plating solution is beneficial to improve the surface hardness,coating thickness and wear scar width of the coating.Therefore,increasing surface roughness of the coating.The corrosion polarization curves of Ni-P-Mn-SiC composite coatings with different SiC nanoparticle diameters were tested by CS350 electrochemical workstation.The self-corrosion potential,self-corrosion current density and corrosion rate were obtained.It was found out that while SiC nanoparticles were increasing,the corrosion performance was reduced.The phase analysis of the coating was carried out,and it was found out that the grain size of the SiC nanoparticles increased during the increase.The best performance of the Ni-P-Mn-SiC composite coating was obtained when the diameter of SiC nanoparticles was 20nm.