电流密度对纯铝微弧氧化膜结构及硬度的影响

Effect of current density on micro-structure and micro-hardness of micro-arc oxidation coatings on aluminum

在恒流模式下,研究纯铝在含有硅酸钠、氟化钾、甘油和氢氧化钾的电解液中的微弧氧化.考察正负电流密度比值恒定时,不同电流密度对陶瓷膜表面形貌、厚度、相组成及显微硬度的影响.结果表明,随电流密度的增大,陶瓷膜表面微孔数量减少,表面微孔孔径和陶瓷膜厚度增大;陶瓷膜主要由α-Al2O3和γ-Al2O3组成,且随电流密度的增大,膜层中α-Al2O3与γ-Al2O3相衍射峰明显增强;陶瓷膜显微硬度随电流密度的增加而增大,显微硬度最高可达27.331 GPa,远高于基体显微硬度的0.687 GPa.

Micro-arc oxidation was carried out on aluminum surface in a solution containing sodium silicate, potassium fluoride, glycerol and potassium hydroxide at a constant applied current density. The influences of different current density on morphology, thickness, phase composition and hardness of micro-arc oxidation （MAO） coatings were investigated when the ratio of anodic current density to cathodic current density was kept unchanged. The results show that with the increase of current density, the number of micro-pores decreases while the size of micro-pores, the thickness and the micro-hardness increase. The MAO coating are mainly composed of α-Al2O3 and γ-Al2O3. The intensity of α-Al2O3 and γ-Al2O3 diffraction peaks increase obviously with the increase of current density. The micro-hardness of MAO coatings can reach 27.331 GPa while that of the substrate is only 0. 687 GPa.