钢熔炼炉对N_2/SF_6气氛中镁合金表面膜的影响  

Effects of Steel Melting Furnace on Surface Films Formed on Magnesium Alloys under N_2/SF_6 Atmosphere

作　　者：聂书红[1] 熊守美[2] 刘争[2] 

机构地区：[1]中国原子能科学研究院,北京102413 [2]清华大学机械工程系先进成型制造重点实验室,北京100084

出　　处：《稀有金属材料与工程》2007年第A03期21-25,共5页Rare Metal Materials and Engineering

基　　金：清华-东洋镁铝合金成形技术研究开发中心项目;博士后基金项目(2004035319);新世纪优秀人才支持计划

摘　　要：在密封的钢熔炼炉中研究了不同温度下0.3%SF_6/N_2气氛中AZ91D镁合金的表面膜成分和形貌,以及表面膜成分与保护效果之间的关系。结果表明:当熔炼温度超过780℃,表面膜中开始检测到铁,随着熔炼温度的增加,表面膜中铁含量逐渐增加。780,810,820℃时,膜中铁含量分别为1.65at%,35.14at%和46at%;当熔炼温度为810℃,表面膜中开始出现孔洞;当熔炼温度超过824℃,表面膜宏观很不平整,AZ91D镁合金显著蒸发。可能原因是780℃以上的熔炼温度下,FeF_3具有很高的蒸气压,FeF_3在钢熔炼炉壁上生成、升华,再到温度更低的小坩埚中心区和Mg蒸汽反应,生成MgF_2和Fe。The compositions and morphologies of surface films formed on AZ91D magnesium alloys were investigated by SEM and XRD in a sealed steel crucible under 0.3%SF6/N2 atmosphere at different temperatures. The relationship between the compositions of surface films and its protective effects were also investigated. The results showed that element Fe was detected in surface film at higher than 780 ℃, and Fe content in surface film increased as the holding temperature increased. The Fe content in surface film were respectively 1.65%, 35.14% and 46 at % at 780, 810 and 820 ℃; holes appeared in surface film at 810 ℃; the surface of AZ91D melt became quite uneven at higher temperature than 824 ℃, and AZ9 ID was remarkably vaporized. The reasons probably were that the vapor tension of FeF3 was very high at higher holding temperature than 780 ℃, FeF3 was formed on the wall of steel crucible and sublimed, then FeF3 gas reacted with Mg, and MgF2 and Fe was formed at the centre of furnace with lower temperature.

关 键 词：镁合金 表面膜 钢坩埚 六氟化硫 氮气 

分 类 号：TG146.22[一般工业技术—材料科学与工程]