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采用显微硬度测试、金相和扫描电子显微分析,研究了固溶工艺对6061硬质阳极氧化膜层厚度、硬度、均匀性、致密度的影响。结果表明:阳极氧化膜因内外表面受到电解液的腐蚀程度不同而表现为氧化膜的硬度自膜层表面到基体逐渐升高。固溶工艺的改变对阳极氧化膜的厚度均匀性无显著影响,氧化膜自身的成分结构决定了其膜层厚度的均匀性。试样在530℃×3 h下采用水冷的方式所获得的硬质氧化膜与基体结合平整,不存在针孔、疏松等缺陷,表面无孔残蚀现象。提高固溶温度,虽然能使强化相Mg2Si、第二相质点等全部回溶到基体里,但因形成粗晶组织,使晶粒度极为不均匀。在而后的阳极氧化过程中造成氧化膜的成长速度不一致,生长快的氧化膜和生长慢的氧化膜之间存在一定的内应力,这种内应力在一定条件下转化为微裂纹,因而使得氧化膜层质量下降,硬度降低。
The effects of solution treatment on the thickness, hardness, uniformity and density of 6061 hard anodized film were investigated by microhardness test, metallography and scanning electron microscopy. The results show that the hardness of the oxide film increases gradually from the surface of the film to the substrate due to the different degree of corrosion of the anodized film on the inner and outer surfaces of the electrolyte. The change of solution treatment has no significant effect on the uniformity of the thickness of the anodized film. The composition of the oxide film itself determines the uniformity of the film thickness. The hard oxide film obtained by the water cooling method at 530 ℃ × 3 h combines with the substrate without defects such as pinholes and porosity, and the surface has no hole erosion. Increasing the solution temperature can make the strengthening phase Mg2Si and the second phase particles be all dissolved back into the matrix, but due to the formation of coarse-grained structure, the grain size is extremely uneven. In the subsequent anodic oxidation process, the growth rate of the oxide film is inconsistent, and there is a certain internal stress between the rapidly growing oxide film and the slowly growing oxide film. Under such conditions, the internal stress is transformed into micro-cracks, so that the oxidation Film quality decline, reduce the hardness.