Electrolytic preparation of Al-Ca master alloy on liquid Al cathode

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｓａｎｅｗｌｙｄｅｖｅｌｏｐｉｎｇｓｕｐｅｒ ｐｌａｓｔｉｃａｌｕｍｉｎｕｍａｌｌｏｙ ,Ａｌ Ｃａａｌｌｏｙｈａｓｎｏｔｏｎｌｙｇｏｏｄｐｌａｓｔｉｃｉｔｙ ,ｂｕｔａｌ ｓｏｇｏｏｄｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｙ ,ｇｏｏｄｗｅｌｄｉｎｇｐｒｏｐｅｒｔｙａｎｄｓｔｒｏｎｇｒｅｓｉｓｔａｎｃｅｏｆｃｏｒｒｏｓｉｏｎａｆｔｅｒｂｅｉｎｇｆｏｒｍｅｄ .Ｔｈｅｒｅｆｏｒｅ ,ａｌｏｔｏｆｍｅｔａｌｌｕｒｇｉｃａｌｓｃｉｅｎｔｉｓｔｓｈａｖｅｄｅｖｏｔ ｅｄｔｏｔｈｅｒｅｓｅａ…     

Preparation of Al-Sr Master Alloy in Aluminum Electrolysis Cell

1 ＩｎｔｒｏｄｕｃｔｉｏｎＡｌ Ｓｒｍａｓｔｅｒａｌｌｏｙｉｓａｋｉｎｄｏｆｍｏｄｉ ｆｉｅｒｓｕｎｄｅｒｄｅｖｅｌｏｐｍｅｎｔ .Ｉｔｈａｓｍａｎｙａｄ ｖａｎｔａｇｅｓｏｖｅｒｏｔｈｅｒｍｏｄｉｆｉｅｒｓ .Ｉｔｓｍｏｄｉｆｙｉｎｇｂｅｈａｖｉｏｒｃａｎｌａｓｔｆｉｖｅｔｏｓｅｖｅｎｈｏｕｒｓａｎｄｆｏｒｓｅｖｅｒａｌｔｉｍｅｓ ,ａｎｄｌｉｔｔｌｅｃｏｒｒｏｓｉｏｎｉｓｏｂ ｓｅｒｖｅｄｄｕｒｉｎｇｔｈｅｍｏｄｉｆｉｃａｔｉｏｎｃｏｕｒｓｅ[1 ].Ｔｈｅｒｅｆｏｒｅ ,ｉｔｉｓｃｏｍｍｏｎｌｙｕｓｅｄｉ…     

Electrolytic properties and element migration in Ni-TiB_2/Al_2O_3composite cathode

With alumina sol as binder and Ni metal as sintering aids,the Ni-TiB_2/Al_2 O_3 composite cathode material for aluminum electrolysis was prepared by coldpressed sintering.The mechanical properties of the composite cathode material were measured.Its electrolytic properties were identified by a 20-A electrolysis test.Cathode samples before and after electrolysis test were measured by energy-dispersive spectroscopy(EDS).The migration behavior of various elements in the electrolysis process was studied by phase analysis.The result shows that Ni metal can effectively fill the gap between the aggregate during the sintering process,which can improve the sintering density of the composite cathode material significantly.The voltage of the 20-A electrolysis test is stable.The impurity of aluminum liquid is 0.42%.The aluminum liquid can wet the cathode surface effectively,and the Ni-TiB_2/Al_2 O_3 composite is an ideal wettable cathode material.In the process of electrolysis,the alkali elements in the electrolyte penetrate the electrode,where K goes deeper than Na.Al generated on the cathode surface will also penetrate the cathode through the gap of the composite material,while Ni in the electrode will spread into the aluminum liquid layer.     

等离子喷涂铝电解可湿润TiB2阴极涂层研究进展

铝电解工业越来越多的采用石墨阴极,石墨阴极具有良好的导电性能,但石墨不被铝液湿润且和铝液形成Al4 C3,导致铝电解槽运行寿命短.可湿润TiB2涂层阴极因节能和延长槽寿命能够给铝电解工业带来显著效益.等离子喷涂是一种高效、灵活的沉积涂层的方法 ,能够在形状复杂或大表面积的基体上沉积金属间化合物、陶瓷或复合材料,涂层厚度可从数微米到数毫米.等离子喷涂制备可湿润性TiB2涂层阴极是可行有效的方法 ,本文评述了等离子喷涂制备可湿润TiB2阴极涂层的研究进展,简述了等离子喷涂工艺受到的影响因素(包括粉末性质、基体表面形貌和焰流性质)和涂层与基体材料结合的机制(包括机械结合、冶金结合和物理结合),分析和讨论了TiB2粉末制备、基体预处理、等离子喷涂工艺参数、涂层显微结构和性能等.最后,指出了等离子喷涂制备可湿润性TiB2涂层阴极工艺将来研究需要解决的几个关键问题.     

电解废旧铝合金回收铝的电流效率(英文)

研究在AlC13-NaCl熔融盐体系中进行电精炼废旧铝合金回收金属铝。以铝合金为阳极,通过直流电沉积在铜阴极上得到铝涂层。在170°C、电流密度100 mA/cm2下电解4 h,得到的沉积物铝的纯度大约为99.7%,电流效率为44%~64%,每千克铝消耗电能3~9 kW·h。探讨阴极电流密度、电解质成分和电解时间及温度等对铝沉积电流效率的影响。结果表明:在AlCl3和NaCl摩尔比为1.3~1.9时,AlCl3和NaCl摩尔比对电流效率的影响很小,升高电解温度有利于提高电流效率;但是延长电解时间或增大电流密度会导致电流效率降低。电流效率的降低主要是由于沉积的铝呈现枝状晶或粉化而易从阴极上脱落到电解质中所致。     

不同粘结剂基TiB_2-C复合阴极中碱金属的渗透迁移行为(英文)

在含K低温电解质熔体中,采用EDS及改进型电解膨胀率测试仪,分别研究电解过程中沥青、呋喃、酚醛、环氧基TiB2-C复合阴极中碱金属(K和Na)的渗透迁移路径。同时,计算并讨论相应的电解膨胀率、碱金属的扩散系数以及复合阴极的腐蚀率。结果表明:无论使用何种粘结剂,电解过程中,碱金属在阴极中表现出相似的渗透迁移路径:碱金属首先渗透进入阴极的孔隙当中,随后渗透进入粘结剂相中,随着电解的不断进行,最后渗透进入复合阴极的骨料相当中。渗透进入粘结剂相和炭质骨料相当中的K和Na均会引起复合阴极的电解膨胀,同时,K比Na有着更强的渗透力。树脂基复合阴极的电解膨胀率、碱金属在其中的扩散系数以及腐蚀率均小于沥青基复合阴极,即,树脂基复合阴极的抗碱金属渗透力强于沥青基复合阴极。而就树脂基TiB2-C复合阴极而言,酚醛基TiB2-C复合阴极的抗渗透力最强,碱金属在其中的渗透速率、扩散系数和相应的腐蚀率分别为4.72mm/h,2.24×10-5 cm2/s和2.31 mm/a.     

添加剂BaO对铝电解用xCu/（10NiO-NiFe_2O_4）金属陶瓷惰性阳极腐蚀性能的影响

制备铝电解用xCu/（10NiO-NiFe2O4）和1BaO-xCu/（10NiO-NiFe2O4）（x=5,10,17）金属陶瓷惰性阳极,在传统电解质中以电流密度1.0A/cm2进行实验室电解腐蚀实验。结果表明：金属Cu被腐蚀,在阳极表面留下了许多孔洞从而导致在电解过程中电解质向阳极内部渗透;金属陶瓷5Cu/（10NiO-NiFe2O4）,10Cu/（10NiO-NiFe2O4）,17Cu/（10NiO-NiFe2O4）,1BaO-5Cu/（10NiO-NiFe2O4）,1BaO-10Cu/（10NiO-NiFe2O4）和1BaO-17Cu/（10NiO-NiFe2O4）的腐蚀速率分别为2.15,6.50,8.30,4.88,4.70和4.48cm/a;添加剂BaO对10Cu/（10NiO-NiFe2O4）和17Cu/（10NiO-NiFe2O4）金属陶瓷的抗腐蚀性能是有利的,因为添加剂BaO能有效提高其致密度从而提高其抗腐蚀性能;但BaO对5Cu/（10NiO-NiFe2O4）金属陶瓷的抗腐蚀性能是不利的,可能是因为聚集在晶界的添加剂BaO加速了金属陶瓷的腐蚀。     

改进的二硼化钛基惰性阴极耐蚀性的研究

用冷压烧结法制造了TiB2-MoSi2惰性阴极,得到致密的二硼化钛基惰性阴极试样。在电解实验后,通过对二硼化钛阴极的表面和剖面的电子显微分析,发现铝液对此种惰性阴极的湿润性好于电解质对惰性阴极的湿润性,避免了电解质与阴极表面的接触,发现惰性阴极的腐蚀为电解南对阴极晶界的腐蚀,测得腐蚀速度为2．22mm/a,证明其耐蚀性能良好。     

阴极等离子体电解氧化表面改性新方法探索

阴极等离子电解氧化(CPEO)打破等离子体电解领域传统认识,利用液相放电现象,使钢铁及钛基材料阴极表面快速氧化,是一种氧化膜制备新方法,提高了材料的耐磨、耐蚀性能。与微弧氧化或阳极等离子电解氧化技术相比,CPEO技术的氧化膜生长速率显著提高,并适用于各种钢铁材料表面改性。介绍了CPEO技术的基本原理,包括液相放电现象和电压电流的演变过程、气膜形成与击穿过程、阴极内部近表面温度随电压变化规律和快速氧化过程,并对比分析了CPEO与阳极等离子体电解氧化和电解渗技术原理的共性与差异。介绍了光发射谱测量和等离子体参数的计算结果,分析阴极等离子体放电环境中阴极等离子体电解氧化机制。进一步总结了碳钢、不锈钢、Mo、TiAl合金表面CPEO膜的形貌、组织结构和性能特点,分析电解液中悬浮的碳粉特性,探讨放电过程中类金刚石(DLC)成分合成的可行性,并初步制备出含DLC成分的CPEO复合氧化膜。最后总结并展望了CPEO技术的发展方向以及应用前景。     

Current density limitation and diffusion boundary layer calculation using CFD method

The knowledge of limiting current density and thickness of diffusion boundary layer is particularly important in improving space-time-yield of electrolysis and especially of high current-density electrolysis. Both natural and forced convection of electrolyte flow are considered in the presented computational fluid dynamics model for calculation of these values. Natural convection is modeled by implementation of a source term at the cathode surface for copper concentration according to Faraday’s law, which allows calculation of electrolyte density for each volume cell of the grid. Forced convection is considered as flow of electrolyte through the cell generated by electrolyte inlet and outlet. By variation of current density, the limiting current density can be calculated with a copperion concentration of zero at the cathode surface after reaching the steady-state conditions in electrolyte. Time dependency of diffusion boundary layer thickness is shown for a chosen cell geometry. Literature data and measured and calculated values of both quantities are in good agreement.     

铝电解质对TiB2镀层的渗透

采用熔盐体系在石墨基体上电沉积制备了TiB2镀层．将TiB2镀层和铝电解阴极碳块和石墨分别作为阴极，考察了Na和电解质对其渗透腐蚀．电解4h后，由酚酞试剂检测表明，Na对TiB2镀层的渗透深度为零，对阴极炭块的渗透深度为16mm，对石墨的渗透深度为4mm．电子探针的分析结果指出，Na和F元素渗透到石墨基体的量很少，元素Al相对较多，TiB2镀层阻碍了Na的产生并减缓了Na的渗透，但没有改变Na的渗透机理．同时。镀层与基体的结合力良好，Al对TiB2镀层的湿润性良好．     

LOW TEMPERATURE ALUMINUM FLOATING ELECTROLYSIS IN HEAVY ELECTROLYTE Na_3AlF_6-AlF_3-BaC1_2-NaCl BATH SYSTEM

1. IntroductionSince the Hall--Heroult process was invented one hundred years ago, it has been the onlyaluminum production method in the w..ldll]. The process has many weak points, such aslow unit productivity; low energy utilization, less than 50%; high electrolytic temperature,usually at 950ap; high consumption of carbon material; serious environmental pollutionand so on. It is well known that the melting point of aluminum is 660ap, therefore, aluminum electrolysis at the range of 700--800C…     

TiB2-C复合阴极中碱金属（K、Na）的渗透及其对阴极电解膨胀的影响（英文）

在不同电解条件下,研究纯KF熔体、纯NaF熔体及其复合电解质熔体中,碱金属(K、Na)在TiB2-C复合阴极中的渗透迁移行为及其引起的阴极电解膨胀。揭示影响阴极电解膨胀性能的主要因素,同时对阴极剖面进行元素微区分析。结果表明:在非极化以及不含铝的电解质熔体中,阴极不会发生膨胀;直接放电所生成的碱金属是造成阴极膨胀的主要因素,引起的阴极最大电解膨胀率可达20.40%;含钾电解质熔体中阴极的电解膨胀率远高于不含钾电解质熔体中阴极的电解膨胀率,最高超出35.13%;与纯钾盐相比,复合电解质对阴极的破坏作用降低;此外,无论是在极化条件还是在非极化条件下,含铝电解质熔体中阴极的电解膨胀率均大于不含铝电解质熔体中阴极的电解膨胀率;同时,在非极化条件下电解质熔体中加入铝后比极化条件下电解质熔体中加入铝后所引起的阴极电解膨胀的增加更为明显。     

铝电解中二氧化锡基（氢气）气体阳极

开发一种在低温电解质（850℃）铝电解中应用的新型二氧化锡基气体阳极以降低铝电解能耗和二氧化碳排放。在此种气体阳极中,氢气通入阳极后参与阳极反应,分别用石墨和铝作阴极和参比电极。采用循环伏安法研究此体系中铂和二氧化锡基电极上氧离子的电化学行为,并确定氧气的析出电势。然后,采用气体电极进行恒电流电解实验,相对于未通入气体和通入氩气,通入氢气后阳极出现明显的去极化现象（阳极电势约下降0.8 V）。实验结果表明,氢气已参与阳极三相界面（气体-电解质-电极）反应,为还原性气体阳极在铝电解上的应用提供了可行性。     

Influence of Atmospheric Plasma-Sprayed Composite Cathode on the Performance of Solid Oxide Fuel Cells

Ni-Al2O3 cermet supported tubular solid oxide fuel cells(SOFCs)with different cathodes were fabricated by thermal spraying.The anode,electrolyte and cathode were deposited by atmospheric plasma spraying(APS)aimed at reducing the manufacturing cost of SOFCs.Three porous composite cathodes of lanthanum strontium manganite(LSM)and yttria-stabilized zirconia(YSZ),lanthanum strontium cobalt oxide(LSC)and YSZ,LSC and scandia-stabilized zirconia(ScSZ)were prepared to investigate influence of cathode constitutions on the cell’s performance.The electrode polarization can be improved through using a composite cathode.The maximum power density of the cell with APS YSZ electrolyte and LSC/ScSZ composite cathode is increased about 12%than pure LSM cathode.The maximum output power density of the cell with APS ScSZ electrolyte and LSC/ScSZ composite cathode reaches 1.0 W/cm 2 at 1000 o C.The further optimization of the performance of plasma-sprayed composite cathode can be made through improving the interface contact between YSZ electrolyte and composite cathode.     

Research progress in TiB<Subscript>2</Subscript> wettable cathode for aluminum reduction

Titanium diboride wettable cathodes are regarded as ideal for aluminum reduction because of their excellent wettability with molten aluminum. The TiB₂ inert wettable cathode materials for aluminum reduction may be divided into three groups: pure TiB₂ ceramic cathode, TiB₂ composite cathode, and TiB₂ coating. This paper briefly describes international research progress on TiB₂ inert wettable cathodes as well as problems faced, and concentrates on the activities of Central South University, Changsha, China, in researching the ambient-temperature solidified TiB₂ cathode coating. At the same time, the results of the coating applied in many aluminum smelters in China are presented, and the pattern of cathode surface of 160 kA cells coated with the ambient-temperature-solidified TiB₂ cathode coating after one year operation is discussed in comparison with the normal cells.     

LOW TEMPERATURE ALUMINUM ELECTROLYSIS IN NaF-AlF3-BaF2-CaF2 BATH SYSTEM

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｉｎｃｅｔｈｅＨａｌＨｒｏｕｌｔｐｒｏｃｅｓｗａｓｉｎｖｅｎｔｅｄｏｎｅｈｕｎｄｒｅｄｙｅａｒｓａｇｏ,ｉｔｈａｓｂｅｎｔｈｅｏｎｌｙａｌｕｍｉｎｕｍｐｒｏｄｕｃｔｉｏｎｍｅｔｈｏｄｉｎｔｈｅｗｏｒｌｄ［１］．Ｔｈｅ...     

Ambient temperature cured TiB_2 cathode coating for aluminum electrolysis

1　INTRODUCTIONAluminumindustryhasbeendevelopingrapidlyinChinainrecentyears ,soderbergcellshavebeenre placedwithmodernprebakecellsinmanyaluminumsmelters,theaveragecelllifehowever ,forprebakecellsinourcountrywasonlyabout130 0d ,muchlowerthantheaveragecelllife ,i.e .above 2 5 0 0d ,forthecellsindevelopedcountries .TiB2 cathodecoating (TCC)couldbeoneofthesolutionstoreducegreatlytheopportunitytotheearlyfailureofcellsandextendthecelllifeofprebakecell[14 ] .Theconceptoftitaniumdiboride (TiB2 …     

Research on the Penetration Depth in Aluminum Reduction Cell with New Type of Anode and Cathode Structures

In this article, a cold water model experiment based on the principle of similitude was conducted to study penetration depth and to investigate the rules of penetration depth (the thickness of bubble sheet) in new anode structure electrolytic cell. New structure anodes and new structure cathodes were designed to examine penetration depth induced by anodic gas in the electrolytic cell. A high-speed camera was used to take photographs of the water model experiment. After that, photographs were analyzed by Image-Pro Plus software. The results revealed the effect of different parameters such as slit width, anode–cathode distance, electrolyte level, and gas rate on the penetration depth. The results provide several meaningful suggestions in selecting electrolysis apparatus. Finally, through dimensional analyzing, the penetration depth criterion equation of the 1/2 anode structure electrolytic cell was obtained. In sum, water model experimental results provide theoretical and experimental basis for the new anode structure and new cathode structure electrolysis cell’s design and practice.     

熔盐电脱氧法制取Ti机理的研究

通过低电压电解实验和不同阴极电解对比实验,并结合循环伏安曲线研究了熔盐电脱氧法制取金属Ti过程中阴极的反应机理。结果表明,在没有金属Ca生成的情况下,TiO2阴极可以直接还原,生成低价钛氧化物。在正常电解的情况下,阴极进行的主要电极反应是TiO2的直接电还原反应,同时在阴极也存在一定的钙热还原反应,只是反应强度比较弱。