AZ91D镁合金微弧氧化膜层高温氧化行为及抗热震性研究

发布时间：2018-04-20 05:37

  本文选题：AZ91D镁合金 + 微弧氧化　； 参考：《长安大学》2015年硕士论文

【摘要】：镁合金具有优良的力学性能和切削加工性能,但其活泼的化学性能却阻碍了其应用范围的进一步扩大,经表面处理后的镁合金可有效改善耐蚀性、耐磨性以及耐热性能。微弧氧化技术作为表面处理技术中最具前途的技术之一,具有工艺简单,生成膜层性能优良等特点。本文在AZ91D镁合金表面在锆盐溶液中通过微弧氧化技术,在不同电参数下制备了不同厚度的微弧氧化膜层,利用SEM、EDS、XRD等分析了膜层的微观形貌及物相组成,通过高温氧化试验和抗热震性试验对比了不同处理电压下获得的膜层的热稳定性,讨论了处理电压对膜层高温氧化行为和抗热震性的影响,研究结果表明:处理电压200V条件下获得厚度为10μm的均匀膜层,处理电压300V条件下获得厚度为17μm的均匀膜层,处理电压下400V条件下获得厚度为37μm的均匀膜层,随着膜层厚度的增加,膜层中疏松层与致密层厚度比例增加;在300℃和400℃条件下加热至128h后,膜层厚度在40μm内的AZ91D镁合金微弧氧化试样,随着膜层厚度的增加,膜层中致密层和疏松层厚度的增加使膜层对氧的阻挡作用增强,膜层中的氧化增重量降低,膜层中能够承载的氧化物极限值升高,膜层破坏程度减轻,膜层在高温下保持完整的时间增加,高温氧化产物主要由镁和氧组成;在400℃条件下进行50次热震试验后,观察试样表面微观形貌可知,试样表面出现明显裂纹的先后顺序为200V试样、300V试样和400V试样,且随着处理电压的升高,试样表面的裂纹数量减少,膜层破坏程度降低;随处理电压的升高,膜层中疏松层厚度的比例增加,膜层整体的韧性增强,能够承受的热震次数增加,抗热震性得到提升。
[Abstract]:Magnesium alloys have excellent mechanical properties and cutting and processing properties, but their active chemical properties hinder the further expansion of their application scope. The surface treated magnesium alloys can effectively improve the corrosion resistance, wear resistance and heat resistance. As one of the most promising surface treatment technologies, micro-arc oxidation technology has the advantages of simple process and excellent properties of film formation. In this paper, microarc oxide films with different thickness were prepared on the surface of AZ91D magnesium alloys by micro-arc oxidation in zirconium salt solution under different electrical parameters. Through high temperature oxidation test and thermal shock resistance test, the thermal stability of the film obtained under different treatment voltage was compared, and the effect of treatment voltage on the high temperature oxidation behavior and thermal shock resistance of the film was discussed. The results show that a uniform film with a thickness of 10 渭 m is obtained at the treatment voltage of 200V, a uniform film with a thickness of 17 渭 m is obtained at the treatment voltage of 300V, and a uniform film with a thickness of 37 渭 m is obtained under the treatment voltage of 400V. With the increase of film thickness, the ratio of loose layer to dense layer increases, and when heated to 128 h at 300 鈩，

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