Emerging SOM technology for the green synthesis of metals from oxides

This article is intended to demonstrate that the environmentally sound solid-oxide-membrane (SOM) technology is an emerging process that can efficiently synthesize metals and alloys directly from their oxide ores with minimum feed-material preparation and produce oxygen gas or water vapor as the major byproduct. To demonstrate the proof-of-concept and economic viability, this article will focus on the synthesis of magnesium metal. The current production methods for magnesium are either metallothermic reduction (magnetherm process) at thig temperatures (1,600°C) involving expensive metal reductant (FeSi) or electrolysis from a halide electrolyte bath that requires extensive and expensive feed-material preparation. Both these techniques are also energy intensive, have low yield and generate large quantities of waste reaction products harmful to the environment. In the SOM process, the oxide reduction is electrochemical and has efficiencies close to 100%. It will be shown that unlike the current metallothermic and the electrolytic processes, the SOM process has the potential to be more economic and less energy intensive, and its process products are environmentally benign. The results reported in this article for magnesium synthesis are also applicable for environmentally sound production of other high-energy-content metals that are produced by less-efficient techniques that result in environmentally harmful reaction products. To date, in addition to magnesium, the SOM process has been used to produce silicon, chromium, and iron, along with alloys from their respective oxides dissolved in appropriate solvents. For more information, contact U.B. Pal, Boston University, Manufacturing Engineering Department, 15 St. Mary’s Street, Boston, MA 02446; (617) 353-7708; e-mail upal@bu.edu.     

自组织分层金属掺杂类金刚石薄膜的研究进展

近年来,研究学者发现在沉积过程中,某些金属元素掺杂类金刚石薄膜时能够形成一种特殊的自组织分层纳米结构,这种纳米结构克服了人为调控多层薄膜的工艺复杂性及局限性,同时赋予了薄膜更加优异的性能。主要综述了国内外对金属掺杂类金刚石薄膜中自组织分层结构的影响因素、形成机理等方面的研究现状。详细阐述了金属类型及含量、沉积条件(脉冲频率、基体偏压、气流比、沉积温度、沉积时间)、沉积方法等参数对自组织分层结构的生成及富金属层厚、富碳层厚、层数等尺寸的作用规律。重点介绍了离子重排机理、金属催化机理、强离子辐照诱导机理和靶中毒机理四种自组织分层结构形成机理的特点,并探讨了目前研究工作中存在的一些不足,如自组织分层结构的形成机理尚不清晰。上述四种机理模型均具有一定的局限性,且如何设计工艺参数实现自组织分层结构的内在调控仍是一个科学难点。针对这些问题,提出了自组织分层结构碳基薄膜的未来研究方向。     

固体透氧膜法与熔盐电解法制备金属铬的对比

利用固体透氧膜(SOM)法电解Cr2O3制取了金属铬并与熔盐电解(FFC)法进行了对比. SEM,EDX和XRD分析表明: SOM法电解2 h,Cr2O3阴极片完全被还原成金属Cr,电流效率为83%,电流密度为0.35 A/cm2;FFC法电解6 h,Cr2O3阴极片只有外层被还原成金属Cr,内层为未还原物相,其电流效率为22%;分析两种方法电流随时间变化的规律表明, SOM法电解速度快,电流效率高,电流密度大、无副反应发生.     

利用固体透氧膜提取海绵钛的新技术

对克劳尔法、电解四氯化钛法等海绵钛传统生产方法以及在熔融CaCl2中直接电解还原二氧化钛制取钛的新工艺进行了总结和分析。针对这些方法中存在的不足,提出了一种利用固体透氧膜技术直接从含钛氧化物矿制备海绵钛的连续、低成本、无污染的绿色冶金新工艺。     

钛提取技术进展

对传统和新发展的各种钛提取技术的基本原理、工艺特点及进展进行了回顾.介绍了目前国内外正在开发或改进的钛生产工艺,其中包括二氧化钛的直接电化学还原法、Armstrong(ITP)法、钙热还原法、金属氢化物还原法、四氯化钛熔盐电解还原钛、SOM法等,指出新工艺在工业应用中存在的问题.作者认为:由于传统的Kroll法生产成本高,限制了钛的应用,只有开发新的、连续化的生产工艺,才能从根本上达到降低生产成本的目的.     

An Environmentally Friendly Process Involving Refining and Membrane-Based Electrolysis for Magnesium Recovery from Partially Oxidized Scrap Alloy

Magnesium is recovered from partially oxidized scrap alloy by combining refining and solid oxide membrane (SOM) electrolysis. In this combined process, a molten salt eutectic flux (45 wt.% MgF₂–55 wt.% CaF₂) containing 10 wt.% MgO and 2 wt.% YF₃ was used as the medium for magnesium recovery. During refining, magnesium and its oxide are dissolved from the scrap into the molten flux. Forming gas is bubbled through the flux and the dissolved magnesium is removed via the gas phase and condensed in a separate condenser at a lower temperature. The molten flux has a finite solubility for magnesium and acts as a selective medium for magnesium dissolution, but not aluminum or iron, and therefore the magnesium recovered has high purity. After refining, SOM electrolysis is performed in the same reactor to enable electrolysis of the dissolved magnesium oxide in the molten flux producing magnesium at the cathode and oxygen at the SOM anode. During SOM electrolysis, it is necessary to decrease the concentration of the dissolved magnesium in the flux to improve the faradaic current efficiency and prevent degradation of the SOM. Thus, for both refining and SOM electrolysis, it is very important to measure and control the magnesium solubility in the molten flux. High magnesium solubility facilitates refining whereas lower solubility benefits the SOM electrolysis process. Computational fluid dynamics modeling was employed to simulate the flow behavior of the flux stirred by the forming gas. Based on the modeling results, an optimized design of the stirring tubes and its placement in the flux are determined for efficiently removing the dissolved magnesium and also increasing the efficiency of the SOM electrolysis process.     

金属结合剂金刚石砂轮制造技术新发展

提高砂轮寿命和磨削效率是金属结合剂金刚石砂轮制造研究的关键问题。本文综述了金属结合剂对金刚石磨料把持能力增强、砂轮修整修锐能力改善两方面的进展，介绍了高温钎焊技术应用与砂轮地貌优化研究的成果，在分析现有技术缺陷的基础上，提出了以高温钎焊技术为核心结合砂轮设计思想的创新制造金属结合剂超硬磨料砂轮换代产品的思路和构想。     

金属零件3D打印技术的应用研究

金属零件3D打印技术作为整个3D打印体系中最为前沿和最具潜力的技术,是目前先进制造技术的重要发展方向。随着科技发展对材料的不断需求,利用快速成形技术直接制造金属功能零件将会成为该技术的主要发展方向。3D打印技术正在快速改变着人们传统的生产方式和生活方式。以数字化、网络化、个性化、定制化为特点的3D打印制造技术被外界认为将推动第三次工业革命。激光工程化净成形技术（LENS）,激光选区熔化技术（SLM）及电子束选区熔化技术（EBSM）3种技术是金属零件3D打印技术的典型代表。对金属零件3D打印技术,包括基本的技术原理及其技术应用领域进行了介绍,最后对金属零件3D打印技术的发展进行了展望。     

A lower carbon footprint process for production of metals from their oxide sources

This paper will describe the solid oxide membrane (SOM) process as it applies to the energy-efficient and environmentally sound production of magnesium from magnesium oxide. Also, it will describe the challenges encountered while using this process for the production of transition metals like titanium from its higher oxides. Finally, a novel magnesiothermic SOM process will be proposed that can enable production of transition metals from its higher oxides.     

基于漏磁/磁记忆组合检测模式的埋地管道缺陷检测研究

在分析埋地管道无损检测技术的基础上,对漏磁检测和磁记忆检测方法在无损检测中的应用进行探讨,结合两者各自特点,提出基于漏磁/磁记忆方法的组合式管道缺陷检测系统思路,并对检测系统体系结构进行分析。根据系统控制的特殊要求,对系统关键技术核心控制电路采用双核控制模式,并对检测系统进行实用测试。结果证明:该检测方式能较好地弥补漏磁、磁记忆检测单一检测方式的不足,具有一定的工程价值。     

基于绿色制造的金属塑性精成形

金属塑性成形加工在产品制造过程中具有举足轻重的地位。但传统的加工方法存在以下不足：材料利用率很低;能源浪费严重;振动、噪声对操作工人以及周边环境产生严重危害和污染。本文综合分析了传统金属塑性成形加工在资源、能源及环境等方面存在的普遍症结,提出了节约资源、能源、环境保护,确保可持续发展是金属塑性成形理论与技术发展的重大课题。实现绿色塑性成形加工,应从技术、工艺和设备三方面入手,走金属塑性精成形之路。     

热流道金属粉末注射成形模具设计

介绍了热流道成形技术的优点,分析了热流道技术在该文金属粉末注射模具实例中的应用,研究了热流道技术在该文金属粉末注射模具实例中应用的结构特点。设计了金属粉末注射成形模具的热流道喷嘴,阐述了热流道技术的优点,展望了热流道技术在粉末注射成形技术的发展前景。     

SOM人工神经网络与阻抗谱方法结合研究涂层的失效过程

    分析了干湿循环条件下有机涂层的电化学阻抗谱特征后选取了阻抗变化率参数作为一维自组织特征映射(self-organizing feature map,SOM)神经网络的训练样本,每个样本对输出层神经元都会产生一定的激发水平,根据该神经网络的特性,输出神经元激发水平的变化趋势便可以反映涂层的降解过程.结合涂层阻抗谱的变化特征,可以把干湿循环条件下涂层的失效过程分为三个阶段,即介质渗入涂层过程,介质到达金属表面诱发金属腐蚀过程和腐蚀扩展涂层剥离过程.     

日本的镁合金旋压技术

镁合金是面向未来、环境友好的实用结构材料,旋转成形是环境友好的材料塑性成形技术,镁合金旋压技术是非常有必要开发研究的环境友好的金属塑性成形高新技术。本文根据所收集的公开资料,对日本近年来针对AZ31、AZ31B镁合金板材所开展的旋压成形技术的研究和开发情况进行了综述,内容包括圆筒形件旋压、车轮旋压成形、旋压缩管以及圆管端部缩口、封头旋压工艺的旋压机床、坯料条件、工件尺寸、加热温度、成形参数、工艺过程以及材料组织和性能变化等。     

Challenges and new insights for exploitation of deep underground metal mineral resources

Long-term and continuous large-scale exploitation has increasingly exhausted shallow metal mineral resources, and deep mining has become inevitable. The current global status of deep mining of metal mineral resources was presented, a series of engineering challenges faced by deep mining were systematically analyzed, and some progress and future innovation focus in key engineering technologies, such as the prediction and prevention of rockburst, cooling techniques, rock support techniques, deep hoisting techniques, and several nontraditional deep mining techniques, were highlighted. Meanwhile, new insights into development strategies of deep mining technology were proposed. The integration of these forward-looking key innovative technologies will form the overall framework of an innovative technology system for the deep mining of metal minerals. This technology system will help to achieve safe, efficient, and green exploitation of deep underground metal mineral resources and ensure the sustainable development of the metal mining industry.     

宽幅砂带磨削工艺在金属加工中的应用

对宽幅砂带磨削工艺在金属加工行业的应用进行综述,包括钣金去毛刺抛光、金属带材抛光、热轧板材氧化皮修磨等;为更好地推广宽幅砂带磨削工艺,从加工成本、加工精度、工件的形态等方面分析影响该工艺推广的要素;最后,对宽幅砂带磨削装备制造如何适应不同金属材料加工进行分析。      

阴极结构对SOM法制备金属钽的影响

在CaCl2熔盐中,利用固体氧离子膜(SOM)法电解还原Ta2O5直接制备金属钽。研究了成形压力与烧结温度对阴极形貌及孔隙率的影响,进而获得阴极微结构对产物形貌及氧含量的影响规律。结果表明:阴极片的颗粒尺寸和孔隙率大小是影响电解还原的重要因素;Ta2O5片的孔隙率随着成形压力的增大、烧结温度的升高明显降低;孔隙率大,有利于电解还原的进行,产物颗粒尺寸大;孔隙率小,会导致阴极产物形成致密的金属外层;在成形压力为4MPa经1150℃烧结2h或6MPa经1100℃烧结2h条件下,阴极反应活性良好,电解产物氧含量低。     

3D打印金属基金刚石复合材料的试验研究

传统方法制造金属基金刚石复合材料工具时,存在胎体对金刚石包镶强度不够、金刚石有效出刃高度小和难以制造具有特殊复杂结构的金刚石工具等问题,而3D打印技术为金属基金刚石复合材料的设计与制造提供了新的发展契机。本研究从金属材料、激光选区熔化（selective laser melting,SLM）成型工艺参数和金刚石参数3方面进行优选,开展SLM成型金属基复合材料的可行性试验,并进一步开展金属基金刚石复合材料的SLM成型试验。结果表明:采用SLM成型技术可提高金属基金刚石复合材料的性能。但同时,新技术的应用也还存在一些不足之处,需要针对性的深入研究。      

Development of an industrial process for minting a new type of bimetallic coin

This paper introduces a technology for minting a new type of bimetallic coin. The coin is manufactured from two metal disks of different materials, one being very thin, joined together by mechanical means during the impartion of the surface details by the minting dies. The proposed technology is based on a multi-stage process consisting of three cold metal forming operations (preforming, rimming and coining) and one intermediate annealing before the coining operation.

The main objective of this work is to present the theoretical and experimental results obtained during the development of the process, which are essential for producing this new type of bimetallic coin. The theoretical analysis was based on the utilization of the finite-element method to characterize metal flow, to establish the process sequence and related intermediate disk geometries, and to design an appropriate geometry for the mechanical joint between the two metal disks.

Experiments consisted on the coinage of several bimetallic prototypes in order to confirm the theoretical predictions and to validate the new proposed technology, which latter can be seen as an alternative to the existing bimetallic coin technology based on the utilization of an outer ring and a central disk.     

半固态金属材料的制备技术及应用

半固态金属成形技术的关键是制备非枝晶结构的半固态金属材料。本文论述了半固态金属材料制备工艺的基本原理与特点 ,介绍了半固态金属材料制备技术的现状与发展概况 ,并展望了半固态金属材料制备技术在我国应用的前景和意义