含S、F的空气气氛对镁合金熔体的保护

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。

Protection of Magnesium Alloy Melting under Atmosphere of Air Containing Sulphur and Fluorine

Protective effects of the atmosphere of FeS2 and HFC-134a mixed with air on magnesium alloy melted in a sealed melting furnace were analyzed.The results show that the atmosphere of air containing both sulphur and fluorine has a good protective effect on magnesium alloy melting,and with the same melting temperature and holding time,it is better than that containing only sulphur or fluorine.The atmosphere with 0.15% HFC-134a and 1g FeS2 can prevent magnesium melt from oxidation and combustion at 730 ℃ for 1 min to 30 min.However,holding for 60 min at 730 ℃,the atmosphere is failure.The characteristics of the surface film formed at controlled condition was analyzed by SEM,EDS and XRD.The protective films formed in the atmosphere of air containing both sulphur and fluorine contain Mg,F,O and S,and the basic phases are MgF2,MgO and MgS.With the increase of holding time,the surface film exhibits more homogeneous,denser and thicker due to the increase of MgF2 and MgS in the MgO-based oxide film.