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在密封容积为13L的镁合金熔炼炉中加入固态硫铁矿(FeS2),研究了FeS2/Air气氛中,FeS2加入量、熔炼温度和保温时间等对AZ91D镁合金熔炼保护效果的影响,并采用SEM、EDS和XRD等对保护膜形貌、成分和相组成等进行了研究。结果表明,试验温度小于760℃时,加入硫铁矿的空气气氛对镁合金熔炼有良好的保护效果。当熔炼温度为730℃时,保温30min,硫铁矿加入量为1g时,保护效果较差;加入量为2g和5g时,保护效果好,加入量为10g时,保护效果变差。在730℃时,当保温时间提高到60min时,2g的硫铁矿保护效果差,将硫铁矿量增至5g时,保护效果良好。熔炼温度提高到800℃,保温30min,2g硫铁矿保护效果差。加入硫铁矿的空气气氛中形成的保护膜由MgS和MgO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。
Solid pyrite (FeS2) was added to a 13L sealed magnesium alloy smelting furnace to study the effect of adding amount of FeS2, melting temperature and holding time on the smelting protection effect of AZ91D magnesium alloy in FeS2 / Air atmosphere. SEM, EDS and XRD on the protective film morphology, composition and phase composition were studied. The results show that when the test temperature is less than 760 ℃, the air atmosphere with pyrite added has a good protective effect on the magnesium alloy smelting. When the melting temperature is 730 ℃, holding time is 30min, when pyrite is added in 1g, the protective effect is poor. When the adding amount is 2g and 5g, the protective effect is good. When adding 10g, the protective effect becomes worse. At 730 ℃, when the holding time increased to 60min, 2g of pyrite protection effect is poor, the amount of pyrite increased to 5g, the protection effect is good. Melting temperature increased to 800 ℃, holding 30min, 2g pyrite protection effect is poor. The protective film formed in the air atmosphere with the addition of pyrite consists of a mixture of MgS and MgO. 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.