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在空气气氛的镁合金密封熔炼炉中加入固态硫铁矿(FeS2),研究了FeS2对AZ91D镁合金熔炼的保护效果,并采用SEM、EDS和XRD等检测分析技术对保护膜形貌、成分和相组成进行了研究。研究结果表明,在空气气氛中,硫铁矿对镁合金熔炼有良好的保护效果。在730℃中保温30 min时保护膜由MgS、MgO和MgF2混合物组成,保护膜致密;保护膜的厚度随保温时间的延长而增加,其厚度在1.0-2.0μm之间。FeS2在空气中分解和氧化生成S和SO2,产物与空气中的O2以及镁液反应生成MgS和MgO,使镁熔体表面氧化膜变致密,从而起到熔炼保护作用。通过热力学分析可知,受热时硫铁矿消耗密封熔炼炉内的氧,并且在表面膜中MgS形成趋势大,形成的MgS的稳定性比MgO好。
The effect of FeS2 on the melting of AZ91D magnesium alloy was studied by adding solid pyrite (FeS2) in air-sealed magnesium alloy smelting furnace. The morphology and composition of the protective film were analyzed by SEM, EDS and XRD. Phase composition was studied. The results show that pyrite has a good protective effect on magnesium alloy smelting in air atmosphere. The protective film consists of a mixture of MgS, MgO and MgF2 when incubated at 730 ℃ for 30 min. The protective film is dense. The thickness of the protective film increases with the holding time and the thickness is between 1.0 and 2.0 μm. FeS2 decomposes and oxidizes in the air to form S and SO2, and the product reacts with O2 in the air and magnesium liquid to form MgS and MgO to densify the oxide film on the surface of the magnesium melt, thereby melting and protecting. Thermodynamic analysis shows that the consumption of pyrite consumes oxygen in the smelting furnace when heated, and the formation tendency of MgS in the surface film is large, and the stability of the formed MgS is better than that of MgO.