Metallurgical Chemistry of Liquid Alloys and Molten Slags

以下研究活动的设计有三个目标：1)开发与液态金属合金和氧化物熔体加工有关的新的基础知识；2)满足研究生和本科生论文项目的要求的主题；3)为学生提供实验技术和材料表征程序方面的实践培训经验的研究，涉及高温炉、先进的电子光学设施、X射线衍射设备和现代分析系统。为了实现这些目标，将根据两个不同的主题进行研究：熔融氧化物中的氮溶解和铁合金中的溶质相互作用。炼铁和炼钢所涉及的过程直接或间接地建立在渣化学控制的基础上，而渣化学又对渣的结构进而对渣的性质和性能产生深远的影响。鉴于控制炉渣的重要性，越来越需要提供有关氧化物熔体和合成熔剂的特性、性质和性能的信息。对低氮钢日益增长的需求促使人们对使用定制设计的焊剂从钢液中脱氮的可能性产生了兴趣。氮可以以两种不同的形式溶解在炉渣中：游离氮化物，其中氮取代自由氧离子；以及结合氮化物，其中氮取代聚合阴离子网络中的氧离子。拟议研究的目的将是利用热重技术和选择性分析方法进行热力学和动力学研究，以量化不同氧化物熔体和合成熔剂中存在的不同氮化物种类，从而更好地了解炉渣化学如何影响炉渣性能。近年来，汽车行业对关键应用的合金铁的需求要求生产非金属夹杂物含量非常低的材料，并严格控制残留元素氧、硫和氮的数量。这些球墨铸铁的球化和高温性能受硅、铝、铈等稀土元素的强烈影响。本项目的目标是使用悬浮液滴来确定这些合金化添加剂对以铁碳合金而不是纯铁为溶剂的氧、硫和氮的活度系数的影响。还将进行坠落液滴实验，以确定当这些合金铁被允许在空气和潜在的保护性大气(如Ar和N)中坠落几分之一秒时所遇到的再氧化行为和氮吸收。*

The following research activities have been designed with three objectives in mind: 1) Development of new fundamental knowledge that relates to the processing of liquid metal alloys and oxide melts; 2) Thematic topics that will fulfill the requirements for graduate and undergraduate thesis projects; and 3) Research that will provide students with hands-on training experience in experimental techniques and materials characterization procedures involving high temperature furnaces, advanced electron-optic facilities, XRD equipment and modern analytical systems. To achieve these objectives, research will be conducted based on two distinct themes: nitrogen dissolution in molten oxides, and solute interactions within iron alloys. ******1. The processes involved in iron and steelmaking are based directly or indirectly on the control of slag chemistry, which in turn has a profound influence on slag structure, and therefore slag properties and performance. In view of the importance of slag control there is an increasing need to generate information pertaining to the characterization, properties and performance of oxide melts and synthetic fluxes. The increasing demand for low nitrogen steel has prompted interest in the possibility of using custom-designed fluxes to remove nitrogen from steel melts. Nitrogen can dissolve in slags in two distinct forms, free nitride where the nitrogen replaces free oxygen ions; and incorporated nitride where the nitrogen replaces oxygen ions involved in the network of polymerized anions. The objective of the proposed research will be to conduct thermodynamic and kinetic studies using a thermo-gravimetric technique and a selective analytical method to quantify the different species of nitrides present in different oxide melts and synthetic fluxes and thus develop an improved understanding of how slag chemistry influences slag performance.******2. In recent years the need for alloy irons for critical applications within the automotive sector have required the production of materials with very low contents of non-metallic inclusions and carefully controlled amounts of the residual elements oxygen, sulphur and nitrogen. The nodularization and high temperature properties of these ductile irons are strongly influenced by silicon, aluminum, cerium and other rare earths. The objective of this project is to use levitated droplets to determine the effect of these alloying additives on the activity coefficients of oxygen, sulphur and nitrogen with iron-carbon alloys, rather than pure iron, as the solvent. Falling droplet experiments will also be conducted in order to determine the reoxidation behaviour and nitrogen absorption encountered when these alloy irons are allowed to fall for fractions of a second through air and potentially protective atmospheres such as argon and nitrogen.  **************************