Study On Preparation And Properties Of Ni-P-ZrO₂ Composite Coating By Magnetic-assisted Jet Electrodeposition

Jet Electrodeposition creating composite coating is a complex electrochemical machining process consisting of electric field,flow field,temperature field and concentration field,and other physical fields.It is wildly has a broad application prospect in various fields,due to its better surface morphology and properties of coating compared to electrodeposition composite coating.Nowadays,many scholars have carried out experimental research on the preparation of composite coatings by electrodeposition assisted by magnetic field,and it is found that the addition of magnetic field can significantly improve the performance of composite coatings.However,few studies on magnetic-assisted ejection electrodeposition,the interaction effects of magnetic field,electric field,flow field,temperature field and concentration field in magnetic-assisted ejection electrodeposition,the growth mechanism of magnetic-assisted ejection electrodeposition composite coatings occured.Based on the ejection electrodeposition test platform,a detachable magnetic carrier platform was built,and the experimental study on the preparation of Ni-P-ZrO₂ composite coating by magnetic-field assisted ejection electrodeposition was carried out.The main research contents are as follows:1.The Magnetic-assisted Jet Electrodeposition system was designed and he magnetic field assisted device was developed.Meanwhile the process test and performance test scheme was proposed,including Jet Electrodeposition and Magnetic-assisted Jet Electrodeposition pretreatment,Jet Electrodeposition and Magnetic-assisted Jet Electrodeposition,and Jet Electrodeposition and Magnetic-assisted Jet Electrodeposition posttreatment.2.The growth mechanism of Magnetic-assisted Jet Electrodeposition was researched,compared with Jet Electrodeposition.This research revealed the adsorption-co-deposition behavior of ZrO₂ nanoparticles by Jet Electrodeposition and Magnetic-assisted Jet Electrodeposition.The coupling models of flow field,electric field and magnetic field were established,and the numerical simulation was carried out.It was found that the influence of magnetic field on the whole process was not the change of macro level but the change of micro level.3.The basic experiment of preparing Ni-P-ZrO₂ composite coating by Magnetic-assisted Jet Electrodeposition was developed.The optimum processing parameters of Jet Electrodeposition and Magnetic-assisted Jet Electrodeposition were determined.According to the dielectric constant and conductivity transformation law,calculated the ZrO₂ nanoparticle addition mass fraction range of 0g/L～25g/L,roughly.Through the composite coating performance tests,the the best ZrO₂ nanoparticle addition mass fraction range was 0～15g/L g/L.4.Study on wear resistance of Ni-P-ZrO₂ composite coating prepared by Magnetic-assisted Jet Electrodeposition.The microhardness and wear resistance of composite coatings prepared by Jet Electrodeposition and Magnetic-assisted Jet Electrodeposition under the different condition of nanoparticle mass fraction were tested by microhardness test and friction and wear test.Microhardness test results showed that under the same condition of nanoparticle mass fraction,each sample prepared by Magnetic-assisted Jet Electrodeposition had higher microhardness compared with the sample prepared by Jet Electrodeposition.When ZrO₂ nanoparticles mass fraction was 10g/L,compesite coating prepared by Magnetic-assisted Jet Electrodeposition had the highest microhardness,739.3 HV.Wear resistance test results showed an increase initially and decrease afterwards trend.When ZrO₂ nanoparticles mass fraction was 10g/L,compesite coating prepared by Magnetic-assisted Jet Electrodeposition had the minimum of grinding parameters,grinding crack width of 367.617μm,the wear depth of 5.673μm,grinding crack section area of 1288.155 μm2.More over,at the same point,the friction mechalism was given priority to abrasive wear,meaning that while the ZrO₂ nanoparticles mass fraction was 10g/L,Ni-P-ZrO₂ composite coating prepared by Magnetic-assisted Jet Electrodeposition had the best wear resistance.5.Study on corrosion resistance of Ni-P-ZrO₂ composite coating prepared by Magnetic-assisted Jet Electrodeposition.Potentiodynamic polarization curves and electrochemical impedance spectrum curve tests and coating corrosion mechanism research was carried out.Potentiodynamic polarization curves and electrochemical impedance spectrum curve of the test results show that under the different condition of nanoparticle mass fraction,the Ni-P-ZrO₂ composite coating prepared by Magnetic-assisted Jet Electrodeposition had lower electrical corrosion parameters and higher equivalent impedance.The results meant that the Ni-P-ZrO₂ composite coating prepared by Magnetic-assisted Jet Electrodeposition had better corrosion resistance and while the ZrO₂ nanoparticles mass fraction was 10g/L corrosion resistance got the peak.On the other hand,Ni-P-ZrO₂ composite coating prepared by Magnetic-assisted Jet Electrodeposition had less voids and microcracks,which made the Ni-P-ZrO₂ composite coating have corrosion performance and protection of Ni-P-ZrO₂ composite coating.