在密封熔炼炉含0.01%HFC134a的氮气中熔炼AZ91D镁合金  

Melting AZ91D magnesium alloy in sealed furnace with protective atmosphere of N_2 containing 0.01%HFC134a

作　　者：聂书红[1] 熊守美[1] 

机构地区：[1]清华大学机械工程系先进成形制造重点实验室,北京100084

出　　处：《中国有色金属学报》2006年第3期436-441,共6页The Chinese Journal of Nonferrous Metals

基　　金：清华东洋镁铝合金成形技术研究开发中心资助项目;博士后基金资助项目(2004035319);教育部新世纪优秀人才支持计划资助项目

摘　　要：在一次性充入含0．01%HFC134a（体积分数）的氮气的密封熔炼炉中，研究了表面搅拌、熔炼温度和熔炼炉密封质量对AZ91D镁合金保护效果的影响以及气氛对熔炼坩埚内壁的腐蚀，并对表面膜形貌、厚度和成分进行了研究。研究结果表明，HFC134a适合充当镁合金在密封熔炼炉中保护气体，氮气是一种好的载气。无表面搅拌时，AZ91D镁合金的最高保护温度是865℃；有表面搅拌时，最高保护温度是800℃。允许熔炼炉内压升率超过10kPa／min。所有保护膜呈致密胞团状结构，膜厚度在1～2μm之间，且比较均匀。而AZ91D镁合金不被保护时，表面膜呈絮状，膜厚度在2～5μm之间变化，厚度很不均匀。随熔炼温度升高，表面膜中C含量逐渐减少到零，表面膜中氧含量逐渐升高。炉内气氛对熔炼炉内壁无可观察到的腐蚀。The effects of holding temperature, stirring and furnace seal quality on the protection of AZ91D magnesium alloy were investigated in a sealed furnace filled once with N2 containing 0.01% HFC134a （volume fraction） before the experiments, the corrosion of the atmosphere to the inner wall of the furnace was analyzed. The morphology, thickness, and composition of the surface films were also studied. The results show that HFC134a is suitable to he the protective gas of magnesium alloys and N2 is a good carrier gas for HFC134a. Without surface agitation, the highest protective temperature for AZ91D melt is 865 ℃ ; with surface agitation, the highest protective temperature is 800 ℃, and the allowable pressure rising velocity in crucible can exceed 10 kPa/min. The morphology of all protective surface films reveals a compact cellular structure with an evenly distributed thickness of 1 - 2μm, whereas that of unprotective films reveals a wadding like structure with an uneven thickness. With the increase of the holding temperature, the carbon content in surface films decreases to zero, and the oxygen content increases gradually. No corrosion of the atmospheres to the inner wall of the furnace is found during the experiments.

关 键 词：镁合金 密封炉 保护气体 表面膜 

分 类 号：TB304[一般工业技术—材料科学与工程]