氧化时间对6063铝合金微弧氧化陶瓷膜的影响

摘要

采用微弧氧化技术在以Na2SiO3为主的碱性电解液中于6063铝合金表面制得均匀的陶瓷膜.研究了陶瓷膜的生长规律,采用扫描电镜(SEM)和X射线衍射(XRD)分别观察和分析了不同氧化时间下制备的陶瓷膜的表面形貌及相组成,并研究了陶瓷膜的完整性和耐腐蚀性能.结果表明,随着氧化时间的延长,膜层的总厚度逐渐增加,膜层的生长由向外生长逐渐过渡到向内生长,表面粗糙度线性增加.膜层内部致密层的硬度高于外面疏松层的硬度,并随着氧化时间的延长,两者硬度的差值增大.膜层主要由α-Al2O3和γ-Al2O3组成,且随着氧化时间的延长,γ-Al2O3含量逐渐减少而α-A12O3的含量逐渐增加.不同氧化时间所得陶瓷膜的y值均大于1,膜层的完整性符合要求,在3.5％(质量分数)NaCl溶液中的耐蚀性随着氧化时间的延长而先增大后减小.%A uniform ceramic coating was prepared on 6063 aluminum alloy surface by micro-arc oxidation in an alkaline electrolyte mainly consisting of Na2SiO3. The growth law of the ceramic coating was studied. The surface morphology and phase composition of the coatings prepared in different oxidation time were observed and analyzed by SEM and X-ray diffraction (XRD), and the integrity and corrosion resistance of the coatings were examined. The total thickness of the coatings is increased with increasing oxidation time, and the coating grows gradually from outward to inward, and the surface roughness is linearly increased. The hardness of the inner dense layer is higher than that of the outer loose layer, and their difference increases with increasing oxidation time. The ceramic coatings are mainly composed of α-Al2O3 and γ-Al2O3. The content of γ-Al2O3 is reduced and that ofrnα-Al2O3 is increased gradually with extending oxidation time. The γ-values of the ceramic coatings obtained in various oxidation time are all greater than 1, and the required integrity of coatings is thus fulfilled. The corrosion resistance of the coatings in 3.5wt% NaCl solution is increased initially and then decreased with prolonging oxidation time.