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对镁合金熔体在密封的FeS2-HFC134a-空气气氛中熔炼的保护效果进行了研究。结果表明,该气氛对Mg熔体有很好的保护效果,并且该气氛比仅含S或者F的气氛的保护效果优越。在熔炼温度为730℃、保温时间为1～30min时,0.15%的HFC-134a+1g的FeS2+空气气氛可以阻止Mg熔体的氧化与蒸发。然而,当保温时间增加至60min时,该气氛不具保护效果。通过SEM,EDS和XRD等检测技术对试验条件下形成的镁合金表面膜进行了检测分析。结果表明,S、F混合气氛下形成的表面膜含有Mg、F、O和S等4种元素,其主要相为MgF2、MgO和MgS。随着保温时间增加,S、F混合气氛下形成的表面膜逐渐变厚,更趋于均匀和致密,这是由于氧化镁基氧化膜中致密度高的MgF2和MgS增加的缘故。
The protective effect of magnesium alloy melt in sealed FeS2-HFC134a-air atmosphere was studied. The results show that the atmosphere has a good protective effect on the Mg melt, and the atmosphere is superior to the S or F atmosphere only. When the melting temperature is 730 ℃ and holding time is 1 ~ 30min, 0.15% HFC-134a + 1g FeS2 + atmosphere can prevent the oxidation and evaporation of Mg melt. However, the atmosphere did not have a protective effect when the holding time was increased to 60 min. The surface films of magnesium alloy formed under the test conditions were tested by SEM, EDS and XRD. The results show that the surface films formed under the mixed atmosphere of S and F contain four kinds of elements, Mg, F, O and S. The main phases are MgF2, MgO and MgS. As the holding time increases, the surface films formed under the mixed atmosphere of S and F gradually become thicker and more uniform and dense, which is due to the increase of the high density MgF2 and MgS in the MgO-based oxide films.