Preparation And Properties Of MAO-MoS₂ Composite Films By Micro-Arc Oxidation And Electrophoretic Deposition Technology

Magnesium alloy has many excellent properties and is widely used in many fields,but magnesium alloy has low hardness,poor wear resistance and corrosion resistance,which limits its application range.In this paper,different MAO-MoS₂ composite layers were prepared on the surface of AZ31 magnesium alloy by Micro-arc Oxidation（MAO）and electrophoretic deposition technology,and the microstructure,phase composition,friction wear and corrosion resistance of different composite layers were studied.This study enriches and innovates the preparation process of magnesium alloy surface coating,and the main research results are as follows:Firstly,the MAO-MoS₂ composite film layer was prepared by electrophoretic deposition technology by introducing MoS₂ particles to the surface of the MAO film layer.The results show that the changes of deposition time,deposition voltage and MoS₂concentration in suspension have a great influence on the friction coefficient,wear rate and deposition amount of MAO-MoS₂ composite layer,and the suitable electrophoretic deposition parameter was determined by the control variable method as 5g/L-50V-3min,and the corrosion resistance of the specimen was greatly improved compared with the magnesium alloy matrix and MAO film layer.Secondly,acrylic acid was introduced into the electrophoretic deposition suspension to enhance the binding force between the composite film layer and the matrix,and the MAO-MoS₂/acrylic composite film layer was prepared.The results show that the MAO-MoS₂/acrylic composite film layer has certain lubricating properties,but there is agglomeration phenomenon in MoS₂ particles in acrylic,resulting in large fluctuations in friction coefficient.In order to reduce the agglomeration of MoS₂ particles,a small amount of PTFE was added to the suspension for modification,which helped to better disperse MoS₂particles,and successfully prepared MAO-MoS₂/acrylic/PTFE composite layer,and the friction coefficient was further reduced.The corrosion current density of both composite layers was 5 orders of magnitude lower than that of magnesium alloy matrix,and the corrosion resistance was greatly improved.Finally,the electroless plating technology was used to enhance the bonding force between the composite film layer and the matrix,and the Ni-P film layer was electroplated on the MAO-MoS₂ composite layer,and the MAO-MoS₂/Ni-P composite film layer was successfully prepared.The results show that the Ni-P film layer has a fixed effect on MoS₂particles,effectively improves the adhesion between the composite film layer and the matrix,and the friction coefficient and wear rate of the composite film layer are lower than those of the MAO layer.The corrosion current density of the composite film layer was higher than that of the MAO layer,but it still has good corrosion resistance compared with the magnesium alloy matrix,and can still play a better corrosion protection role on the matrix.