| Aluminum alloy with low density,high strength,good plasticity,could be processed into a variety of profiles,and it has excellent thermal conductivity,electrical conductivity and corrosion resistance,is the most widely used in the industry of a class of non-ferrous metal structural materials.However,the wear resistance,corrosion resistance and other properties of Al material are still not ideal,it is also necessary to study the insulativity and thermal conductivity of surfaces.Micro-arc oxidation is considered as one of the most practical and promising surface modification technologies to improve the corrosion resistance of Al alloys.In this paper,micro-arc oxidation ceramic coating,ZrO2 micro-arc oxidation complex ceramic coating and AlN micro-arc oxidation complex ceramic coating were respectively prepared in silicate electrolyte system by designing orthogonal test scheme and optimizing technological parameters of micro-arc oxidation.In this paper,micro-arc oxidation complex ceramic coating was prepared on the surface of 1060Al,and its structure and composition were characterized by roughness tester,automatic scratch tester,metallographic microscope,electrochemical workstation,thermal conductivity tester,high resistance meter,X-ray diffraction analysis,scanning electron microscope and other methods.Based on the experimental results,the effects of current density,voltage,silicate concentration,NaOH concentration,micro-arc oxidation time,ZrO2 and AlN addition amount and other factors on the surface roughness,interface adhesion,coating thickness,corrosion resistance,insulativity,thermal conductivity and micro-structure of the ceramic coating were analyzed.The roughness and thickness of ZrO2 micro-arc oxidation complex ceramic coating were significantly affected by voltage.The minimum roughness of ceramic coating were0.82?m,and maximum thickness is 75.52?m.Na2SiO3 concentration has a relatively large influence on the adhesion between the coating and the Al matrix,and the maximum critical load is 98.67 N.ZrO2 can be successfully deposited on the surface of micro-arc oxidation ceramic coating,which is helpful to improve the density of complex ceramic coating,reduce the number and size of micropores in the ceramic coating,and improve the corrosion resistance of the sample relative to the matrix by an order of magnitude after micro-arc oxidation treatment.The effect of current density on the roughness of AlN micro-arc oxidation complex ceramic coating was significant.The minimum roughness of ceramic coating was 0.034?m by orthogonal test.The concentration of NaOH solution also had a great influence on the bonding strength of the ceramic substrate,and the maximum critical load was 29.375N.The addition of AlN has the greatest influence on the thickness and thermal conductivity of the ceramic coating,with the maximum thickness of 15.4?m and the maximum thermal conductivity of 3.9436 W/?mK?.The micro-pores and micro-cracks on the surface of micro-arc oxidation complex ceramic coating with AlN were significantly reduced,and the corrosion resistance of the sample increased by an order of magnitude after micro-arc oxidation.The research on micro-arc oxidation composite AlN ceramic coating shows that the surface roughness of the ceramic coating increases with the increase of current density and time,and the roughness was 1.552?m-4.342?m.The time of micro-arc oxidation treatment has a great influence on the bonding force between the ceramic coating and the Al matrix.The bonding force decreases with the increase of reaction time.The loading load is 7 N-28.5 N.With the increase of current density and reaction time,the thickness of ceramic coating increased,and the thickness of ceramic coating was 18.6-57.3 m.The thermal conductivity of the ceramic coating is 2.3453 W/?mK?-8.5714 W/?mK?,with good thermal conductivity.The surface resistance of ceramic coating is 2.2×109-1.4×10111 M?,volume resistance is 4.7×107-3.33×109 M?·cm,insulation performance is good.The corrosion resistance of micro-arc oxidation complex ceramic coating is improved by 1-2 orders of magnitude. |
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