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Oxidation behavior of molten magnesium in air/HFC-134a atmospheres

Chen, Hukui, Liu, Jianrui, Huang, Weidong
Journal of materials science 2006 v.41 no.23 pp. 8017-8024
X-ray diffraction, X-ray photoelectron spectroscopy, air, energy-dispersive X-ray analysis, equations, magnesium, magnesium oxide, oxidation, scanning electron microscopy, temperature, weight gain
The oxidation behavior of molten magnesium in the atmosphere of air containing HFC-134a has been investigated in the temperature range of 660–760 °C. The oxidation rates and kinetics have been measured by the weight gain method and oxidation products have been characterized by XRD, SEM, EDS, XPS and AES. The results show that the oxidation kinetics is complex which cannot be described by simple equations. The rate of oxidation of molten magnesium in air/HFC-134a covering gas mixtures varies with the concentration of HFC-134a and molten temperature. Increasing the concentration of HFC-134a and decreasing the temperature can slow down the oxidation rate of molten magnesium. The film formed +on the surface of molten magnesium is mainly composed of MgF₂, MgO and C. MgF₂ is predominant product at the top layer and decreased gradually with the depth while MgO and C remain almost constant with relatively low content. The mechanisms of the oxidation of molten magnesium in air containing HFC-134a have also been discussed based on the experimental results.