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对AZ91镁合金熔体在HFC-134a(1,1,1,2-四氟乙烷)/空气气氛中的氧化特性进行了研究。用热重法测定了氧化动力学曲线,用扫描电镜分析了氧化膜形貌,用X-射线衍射仪和X-射线光电子能谱仪分析了氧化膜中氧化产物的组成。结果表明:AZ91镁合金熔体在HFC-134a/空气气氛中的氧化行为主要与HFC-134a的浓度有关。当HFC-134a浓度较高时,氧化表现出抛物线(或直线与抛物线的组合)特征,氧化膜具有保护性,主要由MgF2、MgO、C和少量的AlF3组成;当HFC-134a浓度较低时,氧化表现出线性(或抛物线与直线的组合)特征,氧化膜不具保护性,主要由MgO、Mg3N2和少量AlN组成。另外,熔体温度对该合金的氧化也有影响。
The oxidation behavior of AZ91 magnesium alloy melt in HFC-134a (1,1,1,2-tetrafluoroethane) / air atmosphere was studied. The oxidation kinetics curves were determined by TG method. The morphology of the oxide films was analyzed by scanning electron microscopy. The composition of the oxide products was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The results show that the oxidation behavior of AZ91 magnesium alloy melt in HFC-134a / air atmosphere is mainly related to the concentration of HFC-134a. When the concentration of HFC-134a is high, the oxidation shows the characteristic of parabola (or combination of straight line and parabola). The oxide film is protective and mainly consists of MgF2, MgO, C and a small amount of AlF3. When the concentration of HFC-134a is low , The oxidation shows a linear (or a combination of parabolic and linear) features, the oxide film is unprotected and consists mainly of MgO, Mg3N2 and a small amount of AlN. In addition, the melt temperature also has an effect on the oxidation of the alloy.