Effect Of Solid Lubricant On Microstructure And Tribological Properties Of Aluminum Micro-arc Oxidation

1060 pure aluminum has the excellent plasticity,corrosion resistance,electrical and thermal conductivity,but it exhibits low strength and poor wear resistance.After been treated with the process of the micro-arc oxidation,there be a significant improvement of the hardness,heat resistance,wear resistance and corrosion resistance.But the roughness layer with the porous structure produced by the micro-arc oxidation will generate the greater friction coefficient and the wear-resisting is not ideal.Micro-arc oxidation is a complex physical and chemical reaction which combines the plasma chemistry,electrochemistry and chemical reaction.As a result,not only the impurities in the sample,the processing mode and the electrical parameter of the production but also the composition,concentration and additive of the electrolyte will have an effect on it.The paper puts forward the concept of stepwise lifting pressure,and the ceramic layer of micro-arc oxidation of constant pressure and different stage number is prepared on the basis of the constant pressure mode from the aspect starting with the impact of the research process.The result shows that there is an increase in the thickness of the film and dense layer and the?-Al₂O₃ phase while the roughness decreases.The microhardness of the film and the friction coefficient increase,thus the wear mass loss reduces.The film prepared by the five stage boost voltage mode is much denser.The thickness is about 40.6±2.2?m.The roughness reduces to2.12±0.16?m.The hardness reaches 537±43 HV.The minimum friction coefficient is about 0.75 and the minimum wear mass loss is 3.97×10^-22 mm³.All of these indicate that we can reach the purpose of the increase of the dense layer thickness and the improvement of the ceramic coating quality by the means of the stage boost mode which could match the appropriate pulse energy for different stages of response.Starting with the additives in the electrolyte,the solid lubricant nano-hexagonal particles are chosen as additives.By adding different amount of the nano-BN particles,we prepare the micro-arc oxidation layer containing nano-BN particles on the surface of 1060 pure aluminum by the means of phase constant pressure.The result shows that BN particles are well dispersed in the composite film.The micro-arc oxidation layer prepared by adding 3 g/L nano-BN particles shows the best performance.The surface has the least number of holes and the smallest aperture and the membrane surface is more dense.The thickness is about 93.8±1.9?m,the roughness of the Ra downs to about 3.66±0.14?m.The hardness reaches about 942±51 HV,the friction coefficient reduces to 0.55 and the wear mass loss decreases to 1.18×10^-22 mm³.Addition of BN into the silicate electrolyte system could improve the comprehensive performances of the micro-arc oxidation coating on aluminum.