【作者】 游国强；

【导师】 龙思远；

【作者基本信息】 重庆大学 ， 材料学， 2003， 硕士

【摘要】 镁合金作为现有的最轻的商用金属结构材料，具有比重轻、高比强度、高比刚度，减振吸噪能力强，以及良好的电磁屏蔽能力和铸造性能和易于再生利用等一系列独特的优点，被誉为“21世纪的绿色结构材料”，在国防军工、航空航天、交通工具、3C产品及手动工具等领域有着极为广阔的应用前景。但是在镁合金的规模生产和应用中存在着一些技术瓶颈，制约着镁合金事业的发展。其中，镁合金的易于高温氧化燃烧就是制约其生产应用的首要的瓶颈，由此，镁合金高温下的阻燃保护技术也就成为了关键技术之一。但是我国没有这方面的深入研究和应用的技术及装备，成熟技术被国外公司所垄断，对我国的镁合金事业发展极为不利。本文就是在这样的背景下，在现有技术基础上，研究和开发新型的"镁合金保护气体在线发生"技术及装备，旨在替代现有的以SF6为主的保护技术，并力求达到工业应用的标准。本文从镁及其氧化物的特征入手，较深入地研究了镁及其合金氧化燃烧机理和影响因素，为后面的研究打下理论基础；然后，本文详尽地阐述了“保护气体在线发生”的先进理念和技术细节，并在此基础上，对保护气体在线发生器的研制开发过程以及发生器的整体系统结构进行了介绍，其中包括环境参数对在线发生保护气体反应速率及稳定性的影响及调控机制，在线发生的保护气体成分调控及优化，混合气体在线发生器工作运行的可靠性研究三个方面；最后用混合气体在线发生器进行混合气体与镁合金熔体的交互作用及保护效果研究。通过以上的研究，本文的结论是：镁合金保护气体“在线发生”的思想理念从理论和技术上是完全可行的，实验室检测和工业试用结果表明，在此基础上开发的镁合金保护气体在线发生技术和设备能够在高温下镁合金提供持续稳定的阻燃保护，可以替代现有的以SF6和SO2为主要成分的气体保护技术，与现有技术相比，在成本、烧损率、保护持久性等方面具有明显优势。更多还原

【Abstract】 Magnesium alloys, as the lightest structural material at present , have many advantages, such as high specific strength, high specific rigidity, good casting capability and easy to recycle. As a result, magnesium alloys are named with "Green structural material of the 21th century", and have a huge potential in mass application in road vehicles, aircrafts, space shuttles, communication and electronic goods.However, there are some technical issues restricting the mass production and application of magnesium alloys, among which is oxidation and igniting of Mg alloys at high temperature. Therefore, anti-igniting becomes one of the pivotal techniques in magnesium alloys application. However, the research and development of anti-igniting techniques poor in China, even the anti-igniting technique and equipments are almost all relied on import. This situation is obviously adverse for the development of magnesium products in China. To tackle the igniting problem of Mg melt, this study is mainly devoted to the development of a new technique and equipment to produce Mg protective gas on-line and to replace mixed SF6 protective gas. To do so, this study starts with characterization of the magnesium oxidation and magnesia film, then studies igniting mechanism at high temperatures. Afterward the idea and technical details of producing protective gas on-line are illustrated, followed by design and construction of on-line protective gas generating system. Finally, the protective effects of on-line produced protective gas on AZ91D melt bath are examined systematically.In conclusion, The new technique and equipment of on-line generating protective gas can achieved effectively and reliably anti-igniting protection and can replace mixed SF6 protective gas. Furthermore the technique and equipment of on-line generating protective gas have some obvious advantages, such as cost, loss in melting, and durative of oxidation film.更多还原