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 熔盐中的腐蚀 行为,阳极电流密度为0～2.5A/cm2．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/cm2．此后,腐蚀速度随电流密度的增大而降低．实验证明,高阳极电流密度(＞1.5A/cm2)、熔盐电解质中保持高Al2O3含量和低NaF/AlF3摩尔比,对降低阳极材料的腐蚀速度有利,这也将是惰性阳极应用的重要条件．     

铝电解NiFe2O4基惰性阳极材料纤维增强体的选择

以NiO和Fe2O3为原料采用固相烧结法合成NiFe2O4尖晶石,通过向其中添加短纤维制备纤维/NiFe2O4惰性阳极材料。为选择适合于NiFe2O4基惰性阳极材料的纤维增强体,对几种纤维在NiFe2O4基体中的高温稳定性进行考察。结果表明,高温下碳纤维、玻璃纤维、氧化铝纤维和碳化硅纤维与NiFe2O4基体是热力学不相容的;1 200℃时镀镍碳纤维和镍纤维不能在基体中稳定存在;1 400℃时ZrO2(f)与NiFe2O4基体具有良好的物理和化学相容性,添加3%ZrO2(f)(质量分数)阳极试样的力学性能得到明显改善。因此,ZrO2(f)可作为NiFe2O4基惰性阳极的纤维增强体。     

Ni-Fe-Cu惰性金属阳极的抗氧化和耐蚀性能

对Ni-Fe-Cu合金的抗氧化和耐熔盐腐蚀性能进行了研究.结果显示, 该合金的氧化动力学曲线符合抛物线规则.静态电解质中的溶解腐蚀速率随温度的增高和NaF与AlF3的摩尔分子比的降低而增大.在不同电解条件下, 组成为NaF-AlF3-NaCl-CaF2-Al2O3的电解质体系中电解时, 该阳极周围产生大量气泡, 槽电压在3.6～4.2之间波动, 阳极的电解极化腐蚀速率随电解质中氧化铝浓度的增高、温度的降低而减小, 产品铝的纯度达到97%～98%.     

基于GA-BP的NiFe2O4基金属陶瓷阳极优化设计

采用BP神经网络对铝电解NiFe2O4基金属陶瓷惰性阳极的电解腐蚀过程进行了系统辨识。建立了以Al2O3质量浓度、电解温度、分子比、面积比和电流密度为输入,腐蚀率为输出的网络模型。在材料的设计中,采用了GA-BP优化方法,BP网络参与GA迭代计算时对个体的评价。应用结果表明,NiFe2O4基金属陶瓷惰性阳极的电解腐蚀率预测结果与实测值吻合;优化设计的结果与实验值很接近。     

Co-Ni-xNiFe2O4惰性阳极的电导率及耐腐蚀性能

采用冷等静压-烧结的方法制备了铝电解用Co-Ni-xNiFe2O4(x=5%,10%,15%,20%,质量分数,下同)金属基惰性阳极,并对试样的导电性和抗腐蚀性进行了研究.结果表明阳极试样的电导率随NiFe2O4含量的增加和温度的升高而降低,在900℃时惰性阳极47.5Co 47.5Ni 5.0NiFe2O4和42.5Co 42.5Ni 15.0NiFe2O4的电导率分别为550 S·cm-1和300 S·cm-1.SEM照片表明试样的抗腐蚀性随着NiFe2O4含量的增加而增强.由于氧化作用和铝热反应,电解极化腐蚀速率要比静态腐蚀速率大.     

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。     

电流密度对铝电解NiFe_2O_4基金属陶瓷惰性阳极腐蚀的影响

在Na3AlF6-K3AlF6-AlF3-Al2O 3熔体中,研究电流密度对22(Ni+Cu)/(NiFe2O4-10NiO)金属陶瓷惰性阳极腐蚀速率的影响,并分析腐蚀后阳极的微观结构。结果表明,随着电流密度的升高,NiFe2O4基金属陶瓷惰性阳极腐蚀从以化学溶解腐蚀为主逐渐转变为以电化学腐蚀为主,腐蚀率先降低而后增大。当电流密度从1.0 A/cm2增大至1.6 A/cm2时,阳极年腐蚀率从1.22 cm/a降低至0.137 cm/a;进一步提高电流密度至4.0 A/cm2时,阳极年腐蚀率增大到4.96 cm/a。     

Ti基IrO2＋Ta2O5涂层阳极的析氧电催化活性

通过极化曲线与电化学阻抗谱测试研究了Ti基IrO2 Ta2O5阳极的析氧电催化活性,结果表明,IrO2含量为70％（摩尔分数）时,混合氧化物阳极表面具有具有最高的析氧活性,这缘于该成分含量阳极中活性组元IrO2的真实表面度达到最大;而且,由于表面析出晶粒的最细化,在析氧电位下受析出氧氧的冲击,该成分阳极表面的活性点数目得到最大程度的提高,由此提出决定氧化物阳析氧电催化活性的热力学及动力学判据。     

17（Cu-10Ni）-（NiFe2O4-10NiO）基金属陶瓷在铝电解过程中的相演变（英文）

采用冷压气氛烧结制备17(Cu-10Ni)-(NiFe2O4-10NiO)金属陶瓷,并作为阳极在960°C下分别进行10和40h的铝电解试验。对电解前后金属陶瓷的显微结构、物相成分进行分析检测。对电解质及阴极金属中的杂质含量进行分析,研究阳极组成中Fe、Ni和Cu元素的腐蚀行为。研究发现:在电解过程中,在材料表面形成NiFe2O4相致密层,该致密层随电解时间的延长而增厚。在NiFe2O4相致密层形成与增厚过程中,出现NiFe2O4相吞噬NiO相和金属相氧化的现象,金属陶瓷中Cu元素优先腐蚀溶解。并着重讨论NiFe2O4相致密层形成与增厚过程中金属相的腐蚀形式及NiO相向NiFe2O4相的转变机制。     

新型铝电解阳极-ZrO2固体电解质阳极的研究概述

介绍了新型铝电解阳极-ZrO2固体电解质阳极在国内外的研究情况,并对其工作原理和优点作了简要阐述。     

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。     

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.     

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.     

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。     

Effect of a magnetron sputtered (Al2O3-Y2O3)/(Pt-Au) laminated coating on hot corrosion resistance of 8Nb-TiAl alloy

Novel (Al₂O₃-Y₂O₃)/(Pt-Au) laminated coatings were prepared on 8Nb-TiAl alloy by magnetron sputtering methods. (Na₂SO₄-NaCl)-induced hot corrosion and cyclic oxidation tests were adopted to investigate the high-temperature corrosion behaviours and the mechanical properties of the as-prepared laminated coatings. The results revealed that the multi-sealed (Al₂O₃-Y₂O₃) and (Pt-Au) layers can effectively suppress the inward diffusion of oxygen and corrosive fused salt to an extremely low level at 1000 °C and 900 °C respectively. Consequently, the high-temperature corrosion resistance of the 8Nb-TiAl alloy can be significantly improved. In addition, cyclic tests revealed the (Al₂O₃-Y₂O₃)/(Pt-Au) laminated coating can exhibit enhanced spallation and fracture resistance, which are attributable to the brittle/ductile laminated composite structure by means of energy release mechanisms and the increased thermal expansion coefficient of the coating by the addition of Pt-Au alloy.     

Electrochemical mechanism of hot corrosion of Bi2O3-deposited copper

An electrochemical mechanism of hot corrosion of the Bi₂O₃-deposited copper is proposed. Oxygen ion transport across the oxide scale with liquid-channel grain-boundary structure (LGBS) is the rate-limiting step in the overall mechanism. The calculated and experimental values of the rate constant for hot corrosion of Bi₂O₃-deposited copper are of the same order of magnitude, which shows agreement between theory and experiment.     

Effect of NiO content on corrosion behaviour of Ni-xNiO-NiFe2O4 cermets in Na3AlF6-Al2O3 melts

5Ni-xNiO-NiFe2O4 cermets with different NiO contents were prepared and the corrosion behaviour in Na3AlF6-Al2O3 melts was investigated in laboratory electrolysis tests. The results indicate that adding NiO is unfavorable to the densifieation of NiFe2O4-xNiO ceramics, while small Ni doping can greatly improve the sintering property. The electrolysis tests show that excess NiO is beneficial to the reduction of Fe while has little effects on that of Ni in the bath; the steady-state concentrations of Ni, Fe are below the corresponding solubilities of NiFe2O4-xNiO, implying that corrosion mechanism changes while electrifying. Post-electrolysis examination of anodes shows that Ni metal leaches at the anode surface, yet the substrate ceramic prevents the penetration of bath and the further loss of metal phase.     

铝电解用NiFe2O4-Cu金属陶瓷惰性阳极的制备

以高温固相合成法合成的NiFe2O4陶瓷粉体和金属Cu粉为原料, 采用冷压-烧结法制备了Cu含量在5%～20%之间的NiFe2O4-Cu金属陶瓷惰性阳极, 研究了烧结气氛和烧结温度对其物相组成、微观形貌和基本物理性能的影响. 结果表明 通过控制烧结气氛中氧分压在NiO和Cu2O的离解反应平衡氧分压之间, 可以制备出具有目标物相组成的NiFe2O4-Cu金属陶瓷; 烧结温度和保温时间对所得NiFe2O4-Cu金属陶瓷的相对密度有较大影响; NiFe2O4和Cu之间的不润湿性限制了NiFe2O4-Cu金属陶瓷烧结温度的提高和保温时间的延长, 在保证金属相分布均匀且不溢出的前提下, 所制备的NiFe2O4-Cu金属陶瓷的相对密度较小; 金属相Cu含量越高, NiFe2O4-Cu金属陶瓷最高烧结温度越低、最长保温时间越短, 从而相对密度越低、孔隙率越高; 除了尽量降低金属相含量外, 还可向NiFe2O4-Cu金属陶瓷中添加其他金属如Ni和Co等, 以改善陶瓷相与金属相之间的润湿性, 以提高烧结温度, 进而提高其相对密度和耐腐蚀性能.     

Y2O3-BaO-SiO2-B2O3-Al2O3 glass sealant for solid oxide fuel cells

A glass based on Y₂O₃-BaO-SiO₂-B₂O₃-Al₂O₃ (named YBA) has been investigated as sealant for planar solid oxide fuel cells (SOFCs). The YBA glass has been systematically characterized by differential thermal analysis, dilatometer, scanning electron microscopy, impedance analysis, and open circuit voltage to examine their suitability as sealant. The coefficient of thermal expansion of YBA is 11.64 × 10⁻⁶ K⁻¹ between 323 and 873 K. The resistivity is 9.1 × 10⁴ Ω cm at 800 °C. The glass sealant is found to be well adhered with other cell components, such as electrolytes and stainless steels, at an optimum sealing temperature of 800 °C. All measured results showed that the YBA glass appears to be a promising sealant for SOFCs.