EFFECT OF Cu-Ni CONTENT ON THE CORROSION RESISTANCE OF （Cu-Ni）/（10NiO-90NiFe204） CERMET INERT ANODE FOR ALUMINUM ELECTROLYSIS

（Cu-Ni）/（10NiO-90NiFe204） cermet inert anodes containing metal Cu-Ni0, 5, 10, 15 and 20 wt pct were prepared and their corrosion resistance to Na3AlF6-Al2O3 melts was investigated. The results indicate that the content of metal Cu-Ni has little effect on the steady-state concentration of Ni in the electrolyte and the values could not be used to effectively differentiate their corrosion resistance. The steady-state concentration of Fe decreases from 304×10^-6 to 168×10^-6 and that of Cu increases from 21×10^-6 to 71×10^-6 with the content of metal Cu-Ni increasing from 0 to 20 wt pct. Post-examination shows that metallic phase Cu-Ni is corroded preferentially during electrolysis and many pores are left at the anode surface. Considering the corrosion resistance and electrical conductivity, the cermet containing metal Cu-Ni 5 wt pct should be selected and studied further.     

EFFECT OF Cu-Ni CONTENT ON THE CORROSION RESISTANCE OF (Cu-Ni)/(10NiO-90NiFe2O4) CERMET INERT ANODE FOR ALUMINUM ELECTROLYSIS

(Cu-Ni)/(10NiO-9ONiFe2O4 ) cermet inert anodes containing metal Cu-Ni 0,5, 10, 15 and 20 wt pet were prepared and their corrosion resistance to Na3AlF6-Al2O3 melts was investigated. The results indicate that the content of metal Cu-Ni has little effect on the steady-state concentration of Ni in the electrolyte and the values could not be used to effectively differentiate their corrosion resistance. The steady-state concentration of Fe decreases from 304×10-8 to 168×10-6 and that of Cu increases from 21×10-6 to 71×10-6 with the content of metal Cu-Ni increasing from 0 to 20 wt pct. Post-examination shows that metallic phase Cu-Ni is corroded preferentially during electrolysis and many pores are left at the anode surface. Considering the corrosion resistance and electrical conductivity, the cermet containing metal Cu-Ni 5 wt pct should be selected and studied further.     

Effect of Ni content on corrosion behavior of Ni/（10NiO-90NiFe2O4） cermet inert anode

Ni/（10NiO-90NiFe2O4） cermet inert anodes with metal Ni content of 0, 5, 10, 15 and 20 （mass fraction, %） were prepared and their corrosion behavior in Na3AlF6-Al2O3 melts was investigated in laboratory electrolysis tests. The results indicate that the content of metal Ni in anodes has little effect on the steady-state concentration of impurities Ni and Fe in electrolyte and the values range in （114-173）×10^-6 and （287-385）×10^-6, but the content of impurities in the metal aluminum manifolds. There is preferential corrosion for metal Ni in NiO-NiFe2O4 based cermet anodes. Considering the corrosion resistance and electrical conductivity, the cermet containing 5%Ni （mass fraction） behaves best among NiO-NiFe2O4 based cermet anodes studied, and should be further studied.     

NiFe2O4基金属陶瓷惰性阳极的腐蚀研究进展

综述了近年来国内外铝电解用NiFe2O4基金属陶瓷惰性阳极在阳极组元的溶解与分布、腐蚀率的预测与测定以及氧化物和金属相对阳极腐蚀的影响三个方面所做的研究工作。     

Results from 100 h electrolysis testing of NiFe2O4 based cermet as inert anode in aluminum reduction

1 Introduction Since the Hall-Héroult process was applied in aluminum production, an inert anode was always the target that the aluminum industry was seeking for in the new technology field[1]. Some selection criteria have been defined in order to ident…     

铝电解用NiFe2O4-10NiO基金属陶瓷惰性阳极的耐腐蚀性能

制备铝电解用NiFe2O4-10NiO基金属陶瓷惰性阳极,并在实验室电解槽中考察其电解腐蚀性能。结果表明,电解过程中虽然惰性阳极在960°C熔盐电解质中表现出优异的耐腐蚀性能,但采用XRD、SEM/EDX和金相分析其物相组成和微观结构后发现,电解后阳极中的金属相发生了优先腐蚀,在阳极表面产生大量孔洞。NiFe2O4相中的 Fe 元素的优先溶解可能导致 NiFe2O4晶粒的不均匀腐蚀。溶解在电解液中的 Al2O3与阳极中的 NiO 或FeO 发生反应生成的 NiFe2O4-NiAl2O4-FeAl2O4相对 NiO 相的吞并以及体积膨胀,阳极表面形成致密的NiFe2O4-NiAl2O4-FeAl2O4保护层。因此,致密的NiFe2O4-NiAl2O4-FeAl2O4保护层可以阻挡阳极表面金属相的损失和陶瓷相的腐蚀。     

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。     

THERMAL STRESSES RELAXATION DESIGN OF Ni/NiFe2O4 SYSTEM FUNCTIONALLY GRADED CERMET INERT ANODE

The thermal stresses relaxation of Ni/NiFe2O4 system functionally graded cermet inert anode for aluminum electrolysis was optimally designed. The transient thermal stresses of the inert anode under complex boundary condition during high-temp （955℃） electrolysis were calculated using the finite-element software ANSYS, the influence of different parameters on the distribution of the thermal stresses were analyzed. The results showed that, during the process of thermal shock, the thermal hoop tensile stress on the surface of the anode is very large, which is possibly the major cause of anode crack; when the radius of the anode is between 0.05-0.15m, a range that can be realized by recent manufacturing technology, the optimum composition distribution exponent p is 0.25; The hoop tensile stresses reduce with the decrease of anode scale and also decrease with the decrease of the convection coefficient between the electrolyte and the anode.     

电解质对铝电解用阳极润湿性的研究

测试了熔融状态下三种不同组分的电解质对碳阳极和自制的镍铁尖晶石基金属陶瓷惰性阳极的润湿性.实验结果表明,电解质对惰性阳极的润湿性明显好于对碳阳极的润湿性,不同电解质成分对阳极的润湿角有一定影响.工业冰晶石中加入Al2O3能够改善电解质对阳极的润湿性,添加剂CaF2对提高电解质对惰性阳极的润湿性基本没有贡献.     

铝电解惰性阳极研究现状

惰性阳极是铝工业新技术的一个重要课题,本文对近年来铝电解阳极材料多已集中在金属、金属陶瓷、氧化物陶瓷和氧化铈涂层几个方面的现状及研究进展分别加以介绍。指出铝电解惰性阳极的研制一开始就遇到的问题,如氧化,腐蚀,产出铝受惰性阳极材料的污染,阳极寿命,导电性和成本问题仍未完全解决。     

镍基惰性阳极的耐腐蚀性研究(上)

论述NiO-NiFe2O4基金属陶瓷惰性阳极在熔融电解质中的腐蚀情况，对该镍基惰性阳性的制备过程及抗腐蚀性能进行了深入研究。     

Effect of additive on corrosion resistance of NiFe2O4 ceramics as inert anodes

In order to improve the corrosion resistance of NiFe2O4 ceramics as inert anode, additive V2O5 was added to raw materials NiO and Fe2O3. The inert anodes of nickel-ferrite ceramics were prepared by powder metaUurgic method and the static corrosion rate in Na3AlF6-Al2O3 was determined by mass loss measurement. The effect of V2O5 on sintering property and corrosion resistance was studied. The results show that V2O5 can promote the grain to develop completely and improve sintering property. EDS results show the reaction product Ni2FeVO6 distributes along the grain boundary. The corrosion tests show that V2O5 is beneficial to improving corrosion resistance remarkably. The reasons that V2O5 can improve the corrosion resistance must be V2O5 promoting the gains to develop completely and Ni2FeVO6 distributes along the grain boundary. The stable structure can control the chemical dissolution of ceramics anode and the reinforced grain boundary can control the grain-boundary corrosion rate.     

惰性电极大型铝电解槽设计实验

进行了具有金属陶瓷惰性阳极及TiB2隋性阴极的电解扩大实验研究.电解实验过程38h,电流强度150A,阳极未出现任何破损和变形.相关性能测试结果较理想,阳极腐蚀速率为23mm/a,电解所得阴极铝的纯度经测定达到97.3%.实验证明设计的3000A～6000A平行配置惰性阳极和TiB2惰性阴性新型铝电解槽是可行的.     

Preparation and preliminary testing of cermet inert anode for aluminum electrolysis

1　INTRODUCTIONAluminumhasthelargest productivityamongthenonferrousmetals ,2 4Mtperyearintheworld .Whilegreatprogresshavebeenmadeintheprimaryaluminum production ,theindustrycontinuestopur sueresearchtosolvesomeformidablechallenges ,suchas quitealargeenergyintensity(14 0 0 0 15 0 0 0kW·hpertonaluminum) ,highcon sumptionofcarbonanode(5 0 0 6 0 0kgpertonalu minum) ,significantemissionsofgreenhousegas(1.71tpertonaluminum )andotherdetrimentalgases ,highcapitalinvestmentandcost[1] .Inertelectr…     

Cup-shaped functionally gradient NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript>-based cermet inert anodes for aluminum reduction

Application of inert anode and wet-table cathode technology for aluminum reduction will result in significant energy and environmental benefits, so it has been a research focus for several decades. The candidate as inert anode concentrates on oxide ceramic, cermet, and alloy. This paper reviews briefly the research progress and presents the achievements of Central South University, Changsha, China, in developing an NiFe₂O₄-based cermet inert anode, which includes the preparation and optimization of material performance, the joint between the cermet anode and metallic bar, as well as the results of electrolysis testing for a large inert anode group. At the same time, the problems for NiFe₂O₄-based cermet inert anode faced are discussed.     

Laboratory-scale performance of a binary Cu-Al alloy as an anode for aluminium electrowinning

A binary Cu-Al alloy (9.4 wt.% Al) has been investigated as a potential inert anode for aluminium electrowinning. Anodes have been tested in a laboratory electrolysis cell both with and without preformed oxides. Electrolysis was conducted in cryolitic electrolytes with anode current densities of 0.5 A cm⁻². The anodes operated satisfactorily as measured by electrical parameters. However, substantial corrosion of the Cu-metal substrate was observed. The external oxide generated on pre-treated anodes was porous and allowed the electrolyte to penetrate through to the Cu-metal whereby corrosion was initiated. An untreated anode formed an in situ surface alumina film, but this did not prevent corrosion of the substrate.     

铝电解惰性阳极研究

进行了镍基惰性阳极在熔融质中通电情况下的腐蚀实验,介绍了镍基惰性阳极的抗冲击力,抗腐蚀等性能。     

Further Development on NiFe2O4-Based Cermet Inert Anodes for Aluminum Electrolysis

The new aluminum electrolysis technology based on inert electrodes has received much interest for several decades because of the environment and energy advantages. The key to realize this technique is the inert anode. This article presents China’s recent developments of NiFe₂O₄-based cermet inert anodes, which include the optimization of material performance, the joint between the cermet inert anode and metallic bar, as well as the results of 20 kA pilot testing for a large-size inert anode group. The problems NiFe₂O₄-based cermet inert anodes face are also discussed.     

ZnFe2O4基材料在NaF-AlF3-Al2O3熔盐中的腐蚀

采用锌铁尖晶石材料作为铝电解惰性阳极,考察了这种阳极在ＮａＦ－ＡｌＦ３－Ａｌ２Ｏ３熔盐中的腐蚀行为,阳极电视密度为０￣２．５Ａ／ｃｍ＾２。实验结果表明,锌铁尖晶石材料在阳极极化条件下的ＮａＦ－ＡｌＦ３－Ａｌ２Ｏ３熔盐中具有很好的耐腐蚀性能。在低电流密度下,阳极材料的腐蚀速度随电流密度的增大而增大,最高的腐蚀速度出现于０．５￣０．７５Ａ／ｃｍ＾２。此事,腐蚀速度随电流密度的增大而降低。实验证明,高阳     

Influence of the ratio between Ni and BaCe0.9Y0.1O3−δ on microstructural and electrical properties of proton conducting Ni-BaCe0.9Y0.1O3−δ anodes

Cermet anode substrates Ni-BaCe_0.9Y_0.1O_3−δ (Ni-BCY10) with varied ratios between Ni and BCY10 were prepared. BCY10 powders were prepared by the citrate-nitrate auto-combustion method and anode substrates were prepared by the method of evaporation and decomposition of solutions and suspensions. Sintered anode substrates were reduced and their properties were examined before and after reduction as a function of the ratio between Ni and BCY10. Microstructural properties of the pellets were investigated using X-ray diffraction analysis and field emission scanning electron microscopy. The influence of the Ni:BCY10 ratio on the microstructure of conducting paths through ceramic and metal parts was discussed. Impedance spectroscopy measurements were used for evaluation of electrical properties of the anode pellets. The high conductivity values of reduced anodes confirmed percolation through Ni particles even for an anode with a reduced amount of nickel. Fuel cell tests were carried out in order to examine the influence of the Ni:BCY10 ratio on fuel cell performance and to compare characteristics of cermet anodes with platinum electrodes. The ratio between Ni and BCY10 did have a slight influence on the power output of fuel cells. Fuel cells with a cermet anode demonstrated a higher power output compared to fuel cells with a platinum electrode.