多金属同步电化学还原制备镁合金的基础研究
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摘要
镁合金是在实际应用中最轻的金属结构材料,具有较高的比强度、比刚度,良好的阻尼性、切削加工性及导热性,极强的电磁屏蔽能力以及易回收等特点,被广泛的应用于航空航气、军用品、交通工具等领域,特别是在车辆产业和3C产品中发展尤为迅速。
电化学还原法是制备原镁的两大方法之一。本论文提出一种多金属同步电化学还原直接制备镁合金的新思路。采用熔盐电化学还原理论,计算并分析了理论分解电压和金属的的电极电位。设计了两种实现金属同步电化学还原直接制备镁合金的途径:熔盐法和氧化物法;设计、制作了电化学还原实验装置,并在其上进行了熔盐法多金属同步电化学还原制备镁合金的实验研究。采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射分析仪(XRD)等检测工具对制备的Mg-Al-Sr-Ca合金试样进行了表征;设计了氧化物法制备镁合金工艺,分析了其理论可行性。研究结果表明:
第一,CaCl2具有较强的容氧能力、导电性好、环境影响小、资源丰富、价格低廉等特性,是电化学还原制备镁合金的较为理想的电解质。
第二,在镁-铝合金熔体中电解SrCl2-CaCl2混合熔盐,能够制备出镁-铝-锶-钙合金。SrCl2与CaCl2物质的量为1:1的混合熔盐具有良好的可电解性能,其适宜的电解温度为750℃,电解电压为4V。
第三,熔盐法多金属同步电化学还原制备的Mg-6Al-0.2Al-0.2Ca合金中,锶和钙主要以Al4Sr、Al2Ca的形式存在于基体晶粒晶界处。
第四,将MgO、成分金属氧化物、粘结剂及助剂等混合制成固态阴极,浸在CaCl2熔盐中进行电化学还原,能实现MgO、成分金属氧化物等的同步电化学还原。
Mg alloy are the lightest structural materials with many advantages such as high specific strength,specific stiffness,damping capacity,machinability,heatconducting good magnetic screen and easier to reycle etc. alloys are the lightest structural materials with many advantages such as high specific strength,specific stiffness,damping capacity,machinability,heatconducting good magnetic screen and easier to recycle etc.Mg alloys are widely used in several industrial fields,such as aerospace,weapon,automotiveetc.The application of Mg alloys in automobile and 3C products develops quickly.
Electrochemical reduction is one of the two techniques of preparation of magnesium.A new idea to prepare Mg alloy by synchronous polymetallic electrochemical reduction was proposed in the thesis. In this paper,according the theory of molten salt electrolysis,the decomposition voltage molten salt and the electrode potential of the metals were calculated and analysised. The two routes including molten salt method and oxide process can achieve the target.Then the electrochemical reduction experimental device was designed,and on it a series of experimental studies of Mg alloys electrochemical reduction was finished.And optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),and other inspect means were used to analyse the experimental results.The preparation of electrochemical reduction of oxide solid-state electrode was designed. The results show that:
O2-ion can stay in CaCl2 largely, and the current intensity of CaCl2 was good.Then it was cheap, considered as an ideal electrolyte of this process.
In the magnesium-aluminum alloy melte,SrCl2-CaCl2 molten salt mixture was electrolyzed to prepare Mg-Al-Sr-Ca alloy.The feasible voltage of the mixture was 4.0V,and the fitting temperature was 750℃.
Sr,Ca alloying elements gathered in the dendrite/boundary of the primary phaseα-Mg in the prepared Mg-6Al-0.2Sr-0.2Ca alloy.
The solid-state cathode including MgO/other oxides can be electrolysed in CaCl2?fused salt .It can make thesynchronous polymetallic electrochemical reduction of MgO/other oxides ture.
电化学还原法是制备原镁的两大方法之一。本论文提出一种多金属同步电化学还原直接制备镁合金的新思路。采用熔盐电化学还原理论,计算并分析了理论分解电压和金属的的电极电位。设计了两种实现金属同步电化学还原直接制备镁合金的途径:熔盐法和氧化物法;设计、制作了电化学还原实验装置,并在其上进行了熔盐法多金属同步电化学还原制备镁合金的实验研究。采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射分析仪(XRD)等检测工具对制备的Mg-Al-Sr-Ca合金试样进行了表征;设计了氧化物法制备镁合金工艺,分析了其理论可行性。研究结果表明:
第一,CaCl2具有较强的容氧能力、导电性好、环境影响小、资源丰富、价格低廉等特性,是电化学还原制备镁合金的较为理想的电解质。
第二,在镁-铝合金熔体中电解SrCl2-CaCl2混合熔盐,能够制备出镁-铝-锶-钙合金。SrCl2与CaCl2物质的量为1:1的混合熔盐具有良好的可电解性能,其适宜的电解温度为750℃,电解电压为4V。
第三,熔盐法多金属同步电化学还原制备的Mg-6Al-0.2Al-0.2Ca合金中,锶和钙主要以Al4Sr、Al2Ca的形式存在于基体晶粒晶界处。
第四,将MgO、成分金属氧化物、粘结剂及助剂等混合制成固态阴极,浸在CaCl2熔盐中进行电化学还原,能实现MgO、成分金属氧化物等的同步电化学还原。
Mg alloy are the lightest structural materials with many advantages such as high specific strength,specific stiffness,damping capacity,machinability,heatconducting good magnetic screen and easier to reycle etc. alloys are the lightest structural materials with many advantages such as high specific strength,specific stiffness,damping capacity,machinability,heatconducting good magnetic screen and easier to recycle etc.Mg alloys are widely used in several industrial fields,such as aerospace,weapon,automotiveetc.The application of Mg alloys in automobile and 3C products develops quickly.
Electrochemical reduction is one of the two techniques of preparation of magnesium.A new idea to prepare Mg alloy by synchronous polymetallic electrochemical reduction was proposed in the thesis. In this paper,according the theory of molten salt electrolysis,the decomposition voltage molten salt and the electrode potential of the metals were calculated and analysised. The two routes including molten salt method and oxide process can achieve the target.Then the electrochemical reduction experimental device was designed,and on it a series of experimental studies of Mg alloys electrochemical reduction was finished.And optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),and other inspect means were used to analyse the experimental results.The preparation of electrochemical reduction of oxide solid-state electrode was designed. The results show that:
O2-ion can stay in CaCl2 largely, and the current intensity of CaCl2 was good.Then it was cheap, considered as an ideal electrolyte of this process.
In the magnesium-aluminum alloy melte,SrCl2-CaCl2 molten salt mixture was electrolyzed to prepare Mg-Al-Sr-Ca alloy.The feasible voltage of the mixture was 4.0V,and the fitting temperature was 750℃.
Sr,Ca alloying elements gathered in the dendrite/boundary of the primary phaseα-Mg in the prepared Mg-6Al-0.2Sr-0.2Ca alloy.
The solid-state cathode including MgO/other oxides can be electrolysed in CaCl2?fused salt .It can make thesynchronous polymetallic electrochemical reduction of MgO/other oxides ture.
引文
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[2]晓青.镁合金在汽车上的应用及发展趋势[J].技术导向,2005,(3):38-40.
[3]黎文献.镁及镁合金[M].中南大学出版社:2005.
[4]刘正,王越等.镁基轻质材料的研究与应用[J].材料研究学报,2000,14(5):450-451.
[5]张永建.镁电解生产工艺学[M].中南大学出版社:2006.8.
[6] (苏)别雅耶夫.熔盐物理化学[M].中国工业出版社:1963.7.
[7]沈时英,胡方华.熔盐电化学理论基础[M].中国工业出版社:1965.9.
[8]张明杰,王兆文.熔盐电化学原理与应用[M].化学工业出版社:2006.9.
[9]聂新苗,董凌燕,白晨光. TiO2电解制取Ti的热力学研究[J].材料导报.2006.10.
[10]徐建华,陈建华,邱仕麟.电解法制取铝锶合金的研究[J].轻金属.2001.8.
[11] Masanori Harata, Kouji Yasuda, Hiromasa Yakushiji, Toru H. Okabe.Electrochemical production of Al-Sc alloy in CaCl2-Sc2O3 molten salt [J]. Journal of Alloys and Compounds 474 (2009):124~130.
[12] M. Gibilaro, L. Massot, P. Chamelot, P. Taxil.Electrochemical preparation of aluminium-nickel alloys by under-potential deposition in molten fluorides[J].Journal of Alloys and Compounds 471 (2009):412~420.
[13] C. Schwandt, D.T.L. Alexander, D.J. Fray.The electro-deoxidation of porous titanium dioxide precursors in molten calcium chloride under cathodic potential control[J]. Electrochimica Acta 54 (2009):3819-3829.
[14] A.M. Abdelkader, A. Daher.Preparation of hafnium powder by calciothermic reduction of HfO2 in molten chloride bath[J].Journal of Alloys and Compounds 469 (2009):571~575.
[15]徐日瑶.镁冶金学[M].冶金工业出版社,1981.12.
[16]沈宁福,张东捷,李仲达.新编金属材料手册[M].科学出版社,2003.
[17]曹大力,邱竹贤,徐长伟等.金属镁制备中存在的问题及对策[J].矿冶工程,2006,06:53-56.
[18]陈刚.镁锶合金的制备及其应用[J].中国铸造装备与技术,2005,06:52-57.
[19]叶大伦,胡建华.实用无机物热力学数据手册(第二版)[M].冶金工业出版社,2002.
[20]周明付.高锆镁锆中间合金工艺研究[J].湖南有色金属,2003,08:32-34.
[21]张明杰,李继东,郭清富.真空铝热还原法生产金属锶[J].东北大学学报,2004,(12): 1176-1178.
[22] Wei-dong XIE,Xiao-dong PENG,Qun-yi WEI.Preparation of Mg-Sr Alloys Using VacuumReduction: A Thermodynamics Approach[J].Materials Science Forum,Vols.546-549(2007): 463-466.
[23]贺圣,李宗安,颜世宏.YF32LiF熔盐体系中氧化物电解共沉积钇镁合金的阴极过程研究[J].中国稀土学报,2007,(2):120-123.
[24]杨少华,曹晓舟,班允刚.熔盐电解法制取Al-Mg-RE三元合金[J].稀有金属材料与工程, 2007,(3):509-512.
[25] A.-M.Lafront,W.Zhang,S.Jin,R.Tremblay.Pitting corrosion of AZ91D and AJ62x magnesium alloys in alkaline chloride medium using electrochemical techniques[J]. Electrochimica Acta,51(2005)489-501.
[26]杨宝刚,高炳亮,杨振海,邱竹贤.制取铝锶合金在我国的研究进展[J].轻金属,1999, (1):33-35.
[27]李继东.生产金属锶及铝锶合金新工艺的研究[D].东北大学学位论文,2006.
[28] Zhang Z,Bian X F,Wang Y.Formation of microstructures of an Al-10wt%Sr alloy prepared by electrolysis and mixing[J].Materials Letters,2003,57(7):1261-1265.
[29] Nianchun Liu,Weidong Xie,Xiaodong Peng.Preparation of Mg-Sr Alloy using Electrochemical Reduction[J].Advanced Materials Research,Vols.26-28(2007):119-123.
[30] Xie W.D.,Liu N.C.and Peng X.D,CN Patent 200710078629.8(2007).
[31]刘年春,谢卫东,彭晓东.Mg-Sr合金制备技术新进展[J].轻金属,2007,(11):55-59.
[32]汤燕,谢卫东,彭晓东.熔盐电解法制备镁-铝-锶-钙合金新工艺[J].机械工程材料,2009,10.
[33]李继东,张明杰.熔盐电解生产Al-Sr合金的新工艺及其加料周期[J].材料与冶金学报,2005,(1):17-20.
[34]谢刚.熔融盐理论与应用[M].北京:工业出版社,1999,101-177.
[35]杨绮琴.熔盐技术的应用[J].大学化学,1994,9(3):1-5.
[36]张明杰,邱竹贤.槽电压的内涵[J].有色矿冶,1991,(2):32-36.
[37]刘奎仁,陈建设,魏绪钧.钕电解相关物质理论分解电压的计算[J].稀土,2001,(2):30-33.
[38]陆原尔.锂电解理论分解电压计算点滴[J].新疆有色金属,1992,(1):66-68.
[39]王永利,王秀兰.杂质对镁电解过程中的影响[J].张家口师专学报,2003,(6):72-76.
[40]王凤至,张素霞.自制大电流直流可调电源[J].河北师范大学学报(自然科学版),1994,(2).
[41]沈龙大,李凯,张少明.有色金属电解可控整流稳流电源及无功补偿滤波装置[J].轻金属,1999,(9):54-57.
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