【作者】 邵秀云；

【导师】 孙剑飞； 刘洪汇；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2010， 硕士

【摘要】 镁合金化学性质活泼,液态的镁极易和大气中的氧气、氮气及铸型中的水发生反应,结果在铸件表面出现孔洞或氧化皱皮,降低铸件表面质量,给生产企业带来很大的压力。本文对镁合金阻燃涂料原料选择、配比、浇注效果等进行了研究。对单一主要助剂种类及加入量对涂料工艺性能的影响进行了试验与分析。重点研究了硅溶胶、聚乙烯醇缩丁醛(PVB)、酚醛树脂、凹凸棒土、耐火骨料对涂料流变性、触变性、粘度、悬浮性、密度、透气性、常温强度、高温强度及高温抗裂性的影响。研究发现硅溶胶作为粘结剂,涂料常、高温强度不高,达不到使用要求,而酚醛树脂粘结效果较好,可以代替硅溶胶。最终确定涂料的成分组成为氧化铁红70%、滑石粉20%、石英粉10%,酚醛树脂4%、凹凸棒土3%、聚乙烯醇缩丁醛(PVB)0.25%、硼酸3%、十二烷基磺酸钠0.2%。将研制涂料与意大利阻燃涂料性能进行对比发现,研制涂料密的密度、发气量、透气性及悬浮性均高于意大利涂料,而两者的常、高温强度及高温抗裂性相差不大。研制涂料与意大利涂料的镁合金充型高度对比发现,研制涂料保温能力强,充型高度比意大利涂料高15%,更适合于镁合金的铸造生产。在铸造车间进行了该涂料的现场浇注实验。实验结果表明:涂料阻燃性能好,涂层强度高,没有出现急热开裂和塌箱等现象;透气性良好,浇注充型平稳,未出现反喷、浇不足等现象;抗粘砂性能强;而且涂料层容易脱落。研制的涂料可满足生产实际需要。更多还原

【Abstract】 Chemical properties of magnesium element is very active, when being liquid, it can easily react with oxygen and nitrogen of the air and water in the mold. As a result, pores and oxide skin appear on the surface of cast magnesium alloy, and the casting surface quality reduces, which had caused great pressure on manufacturers.This paper first study the effect of silicasol, polyvinyl butyral, phenolic resin, attapulgite and fire-resistant aggregate on the physical properties that is rheology, thixotropy, viscosity, suspensibility, density, permeability, strength under ambient and high temperature, as well as the cracking resistance under high temperature. The results show that the strength of the coating with silicasol as binder agent under ambient and high temperature is too low to reach the application requirements, while that with phenolic resin as binder agent has well bonding effect and can be used as a substitute of silicasol. Then we optimize the content of the raw materials, ferric oxide 70%, talc 20%, quartz powder 10%, phenolic resin 4%, attapulgite 3%,polyvinyl butyral 0.25%, Boric Acid 3% and SDS 0.2%.The properties of the developed flame retardant coating and the Italian coating were compared. The density, gas evolution, permeability and suspension property of the developed coating were better than that of the Italian coating, while there is no obvious difference in the strength under ambient-temperature and high-temperature and high temperature cracking resistance of the two coatings. The filling height in the casting of magnesium alloy using the developed flame retardant coating and the Italian coating as retardant coating also were compared, it was found that the filling height of developed flame retardant coating was 15 percent higher than that of the Italian coating, so the developed coating is suitable for the castings of magnesium alloy.Casting experiments show that the developed coating has good flame retardancy and high strength; acute thermal cracking and sand crushing did not happen; the permeability was well and the pour filling was steady; the reverse ejection and missrun phenomena did not appear. Moreover, the ability of resisting sand penetration was well. The coating can be easily split away off. Therefore, the developed coating can meet the actual needs of the casting of magnesium alloy.更多还原