Preparation And Research Of Self-Lubricating Ceramic Coating On Aluminium Alloy By Micro-Arc Oxidation

In this paper,aluminum alloy ZL109 was used to research,ceramic layer was prepared on the surface of aluminum alloy substrate by WHD-20 micro-arc oxidation power source.Electrolyte parameters and electrical parameters are key factors which influence the performance of ceramic coatings on aluminum alloys.This paper uses orthogonal experiment to optimize the best electrolyte parameters.,the final electrolyte formulation was 10g/L sodium silicate,5g/L sodium tungstate,2.5g/L potassium hydroxide,2g/L EDTA.A single optimization method was used to optimize the electrical parameters,the forward voltage was 400V?450V,the negative voltage was 120V-140V,the duty ratio was 20%,and the power frequency was 500Hz.The ceramic layer which contains MoS2 was prepared by adding self-lubricating nano-particles of molybdenum disulfide into the electrolyte.The properties of the ceramic layer were evaluated by analyzing the film thickness,hardness,composition,phase composition and surface topography.The results show that the presence of MoS2 is detected on the shallow surface of the ceramic layer,and the self-lubricating particles are introduced into the ceramic layer.When MoS2 is added,the ceramic particles on the surface of the film become smaller,and the surface roughness of ceramic layers is reduced.Compared with the blank surface without MoS2,the thickness of layer is reduced slightly,but the hardness of the ceramic layer did not change significantly,and the Vickers hardness was above 1000HV.In the friction and wear experiments,the film which contains MoS2 nanoparticles shows a lower coefficient of friction in the state of dry friction and oil-poor lubrication,when the concentration of MoS2 is 5g/L,the layer shows the lowest coefficient of friction,and the friction coefficient decreased by 50%.At the same time,the wear amount of the sample is the lowest.The phase composition of the ceramic layer changes slightly after the addition of MoS2 particles.Some of the mullite and?-Al2O3 are transformed into ?-Al2O3,and the main component of the film is ?-Al2O3.