单极性脉冲电流密度对铝合金MAO膜相结构和微结构的影响

Effects of Unipolar Pulse Current Density on the Phase Composition and Microstructure of Aluminium Alloy MAO Coating

利用微弧氧化(MAO)技术在铝合金表面沉积陶瓷膜,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电子能谱(EDS)和显微硬度方法,研究了MAO过程中单极性脉冲电流密度与氧化膜力学性能和化学成分的关系.发现在较高电流密度下制备的陶瓷膜中含有较多的α-A l2O3相,而在较低电流密度下制备的陶瓷膜主要由γ-A l2O3相组成.对陶瓷膜截面上不同厚度处的膜层化学成分分析表明,组成氧化膜的主要物质-αA l2O3和-γA l2O3的比例随深度的变化呈现出复杂的变化规律,这一结果与相关的文献报道有所不同.

The ceramic coatings on the Al-alloy substrate have been synthesized by means of microarc oxidation （MAO） technique. Effects of the unipolar pulse current density on the mechanical and chemical properties of the coatings have been studied via XRD, SEM, EDS, and microhardness test. The samples fabricated at high current densities consist mainly of α-Al2O3 phase, while the samples fabricated at low current densities are almost completely composed of γ-Al2O3. The content analysis on the cross-section of the coating indicates that the ratio of α-Al2O3 content to γ-Al2O3 content shows complicated changes with the variation of the film depth, which is different from the results reported from other literatures.