Preparation And Properties Of Densified Anti-Corrosion And Wear-Rresistant PEO Ceramic Coatings On Magenesium Alloy Surface

Compared with other metal materials,magnesium alloy materials have more excellent material properties,such as higher specific strength and specific stiffness,electrical shielding,easy processing,etc.Therefore,magnesium alloy materials have a very broad application field and have been widely used.Used in transportation,aerospace,biomedical and many other fields.Due to the relatively active nature of magnesium,the shortcomings of magnesium alloys such as non-corrosion resistance,non-wear resistance and large friction coefficient limit its continued development in various fields.At this stage,the micro-arc oxidation film prepared by the micro-arc oxidation technology has a significant effect on increasing the corrosion resistance and wear resistance of the film.However,in order to further improve the performance of the film in all aspects Micro-arc oxidation PEO ceramic coating is prepared on the surface of magnesium alloy by using arc oxidation technology and the combination of adding nanoparticles,which further improves the corrosion resistance and wear resistance of magnesium alloy materials.Therefore,based on the preparation of micro-arc oxidation PEO ceramic coating on the surface of AZ91D magnesium alloy,nano-ZrO2 particles were compounded in the film layer,and the process parameters,nano-ZrO2 particle size and content on the corrosion resistance and corrosion resistance of PEO ceramic coating were studied.The influence of wear resistance,and the wear mechanism and corrosion mechanism of PEO ceramic coating were discussed.Firstly,the effects of the pulse frequency of the micro-arc oxidation.power supply,the concentration of EDTA-2Na in the electrolyte and the content of ZrO₂ in the electrolyte on the thickness and electrochemical impedance of PEO ceramic coating were investigated by response surface method.The results showed that all three were correlated with the response results.The order of the influence degree of the three is:the pulse frequency of the micro-arc oxidation power supply>the content of ZrO₂ in the electrolyte>the concentration of EDTA-2Na in the electrolyte.Secondly,under the experimental conditions of the power pulse frequency of 200Hz and the concentration of EDTA-2Na in the electrolyte of 5g/L,the effect of the particle size and content of the nano-ZrO₂particles in the electrolyte on the structure and properties of the micro-arc oxidation PEO ceramic coating was studied.Influence.The particle diameters of the nano ZrO₂particles are selected as 30nm,50nm and 100nm,and the contents of the nano ZrO₂ particles in the electrolyte are set as 1g/L,2g/L and 3g/L.The experimental results show that the nano ZrO₂ particles can be successfully infiltrated into the PEO ceramic coating.The ZrO₂ particles in the film are mainly distributed in the loose layer,and there are MgO and Mg₂SiO₄ phases in the film.The hardness test results show that the hardness of PEO ceramic coating is higher than that of ordinary micro-arc oxidation coating.In terms of wear resistance,because the distribution of nano-ZrO₂ particles on the surface of the film layer improves the wear resistance of the film layer and reduces the friction coefficient of the composite film layer,the PEO ceramic coating prepared with a particle size of 100nm and a content of 2g/L The wear resistance of the layer is the best.In terms of corrosion resistance,the corrosion resistance of PEO ceramic coatings is higher than that of ordinary micro-arc oxidation coatings.The fog test further shows that the PEO ceramic coating has better corrosion resistance under this condition.Finally,the influence mechanism of nano-ZrO₂particles on the micro-arc oxidation PEO ceramic coating is discussed.