添加稀土复合氧化物对耐火浇注料性能的影响

对Al2O3-SiC-C超低水泥浇注料引入稀土复合氧化物进行了研究,以便进一步改善和提高浇注料的高温性能.试验结果表明,配加适宜的稀土复合氧化物可以提高耐火浇注料力学性能,并促进莫来石(3Al2O3·2SiO2)生成,从而改善浇注料显微结构和高温结构性能.     

球式热风炉用耐火球性能的对比分析

对用于球式热风炉的高铝质、硅质和高密度镁铝质耐火球的理化性能和热工特性进行了研究,对其使用效果进行了分析。结果表明:高密度镁铝质耐火球有利于热风炉蓄热和热传递,同时可解决粘球问题;其在长期高温负荷作用下,能保持结构稳定,不发生脆化和软化。     

火焰喷雾热解法合成稀土氧化物

综述了火焰喷雾热解法合成稀土氧化物条件以及产品性能和其应用研究现状,阐述了不同前驱体、火焰温度、停留时间等条件对稀土氧化物粒度、比表面积、相结构、热稳定性等因素的影响,重点介绍了异辛酸稀土作为前驱体或醋酸稀土添加高燃烧焓的有机溶剂合成热稳定性高、比表面积大的纳米稀土氧化物,以及在高火焰温度下合成单斜相稀土氧化物,并对火焰喷雾热解法合成的稀土氧化物应用及未来发展前景进行了展望。     

稀土硬质合金的研究现状及发展趋势

稀土被称为“工业维生素”,由于具有一系列特殊的性质,已广泛应用于冶金材料、光学、电子学、磁学、机械、化学工业、原子能、农业和轻工业等部门。稀土做为各种添加剂、变质剂,其本身直接产值和利润虽不高,但所产生的二次经济效益可增殖数十倍甚至数百倍。钢中加入少量的稀土元素可以提高强度,净化杂质,细化晶粒,改变杂质的存在形态和分布,使其性能得到改善,从而提高钢的质量。在粉末冶金铁基制品中添加少量稀土氧化物也可很大程度地改善制品的性能。     

球式热风炉耐火球球床损毁分析

以柳钢1 500 m3高炉球式热风炉损毁球床为研究对象,分析三段式球床从上至下存在粉化、变形黏结、粉体球体混合黏结的损毁原因:刚玉质耐火球的尖晶石化、高温荷重下高铝质耐火球的变形黏结以及中温下Φ45 mm高铝质耐火球与粉体混合黏结等3种因素共同作用。     

提高窑县耐火制品使用寿命的措施

本文简述陶瓷、电子磁件工业窑具用耐火制品的使用情况及各种材质的窑具耐火制品性能，阐明应根据不同使用条件选用不同材质的窑具耐火制品；揭出窑具耐火制品生产工艺中应值得注意的几个问题．     

提高窑具耐火制品使用寿命的措施

本文简述瓷，电子磁件工业窑具用耐火制品的使用情况及各种材质的窑具耐火制品性能。阐明应根据不同使用条件选用不同材质的窑具耐火制品揭出窑具耐火制品生产工艺中应值得注意的几个问题。     

稀土氧化物对连铸保护渣结晶温度的影响

为了解决稀土钢浇注时因稀土氧化物进入保护渣导致保护渣性能改变的问题,用热重一差热分析仪系统地观测了稀土氧化物对不同碱度及BaO、B2O3和Li2O含量的保护渣结晶温度的影响。结果表明,稀土氧化物对保护渣结晶温度影响显著,特别是稀土氧化物从零增至5％时最为明显。随着稀土氧化物含量的继续增加,保护渣结晶温度缓慢升高。低碱度可以抑制保护渣中稀土矿物初生晶核的析出;BaO有利于稀土氧化物在保护渣中的溶解和扩散;B2O3基本上可消除稀土氧化物引起的保护渣结晶温度升高的不良影响;Li2O可阻止高熔点结晶相的析出,降低含稀土氧化物保护渣的结晶温度。     

稀土氧化物粒子对钼合金粉末冶金过程及力学性能的影响

试验研究了掺杂La2O3、Y2O3、CeO2稀土氧化物颗粒对钼合金的粉末物性、烧结进程、制品的烧结致密度及压力加工丝材的室温力学性能的影响规律。试验结果表明,掺杂稀土氧化物粒子细化了钼粉的粒度,降低了松装密度和粒度分布范围,同时导致粉末团聚现象增多;稀土氧化物粒子延迟了钼合金的烧结进程,降低了烧结制品的致密度,同时细化了烧结体晶粒尺寸。稀土氧化物粒子以弥散强化和细晶强化的形式,提高了钼合金丝的室温强度。CeO2显著提高了钼合金丝的室温韧性,La2O3、Y2O3则降低了钼合金丝的室温韧性。     

磷酸盐耐火材料结合剂的优点

一、FFB A、应用范围和场合: FFB32是一种酸性结合剂,由于它能与各种耐火材料氧化物或氧化物混合物起不同反应,因此它能够作为一种化学结合剂使用于酸性和中性耐火材料中。这包括就耐火原料方面而言,这几乎包括:所有高铅质的,即Al O含量大于45％的耐火材料制品,例如铁矾士、硅线石,刚玉和纯Al O制品;另外还包括SiO_2类酸性材料,例如粘性砂、石英砂、SiC和氧化锆(二氧化锆)。     

陶瓷用原料超细氧化钇的制备工艺

采用氯化钇溶液为原料,草酸/草酸铵为复合沉淀剂,采用共沉方式,得到氧化钇的前驱体,经灼烧后制得Y2O3粉末。研究了复合沉淀剂的组成、料液浓度、反应温度、加料速度等对沉淀颗粒大小的影响。结果表明,在选定条件下,采用草酸/草酸盐为复合沉淀剂能够制备出D50小于1.0μm的超细氧化钇粉末,可用于高性能稀土复合钇锆陶瓷的原料。     

Influence of rare-earth modification on the formation of nonmetallic inclusions in high-carbon steel

The content of nonmetallic inclusions when rail and wheel steel is produced by intensive modern technology and modified by rare-earth metals is analyzed. The composition, morphology, dimensions, and distribution of the inclusions in the steel are determined in the case without oxidation by aluminum or treatment by silicocalcium and also with treatment of aluminum-bearing steel by both rare-earth metals and silicocalcium. Modification with rare-earth metals reduces the content of oxide inclusions in the rail and wheel steel. That improves the plasticity and impact strength of the products.     

The Recovery of a Mixed Rare-Earth Oxide and the Preparation of Cerium,Europium and Neodymium Oxides from a South African Phosphoric Acid Sludge by Solvent Extraction

Abstract

A novel process based largely on solvent-extraction methods has been developed for the recovery of rare-earth oxides from waste calcium sulphate sludges obtained during the manufacture of phosphoric acid from a South African apatite ore. A mixed rare-earth oxide (90-98% purity) was first recovered from calcium nitrate leach liquors by extraction with TBP or DBBP, after which it was dissolved in nitric acid to enable pure cerium dioxide (99.98%) to be prepared by selective extraction of cerium(IV) nitrate into TBP. The heavy (yttrium), middle, and light rare-earth fractions were then separated by sequential extraction into D2EHPA at controlled pH values. Pure europium oxide (99.98%) was isolated from the middle fraction by reductive precipitation of europim(II) sulphate, followed by conversion to soluble europium(II) chloride and removal of trivalent rare-earth impurities by extraction with D2EHPA or Versatic 10 acid. Finally, magnet-grade neodymium oxide (95-96%) was obtained from the light rare-earth fraction by extraction of the contained lanthanum, cerium and praseodymium into Aliquat 336 nitrate.     

脉冲电解掺杂制备二氧化锰及其性能研究

采用脉冲电解和电解液中加入混合稀土氧化物的方式制备了改性电解二氧化锰。通过循环伏安、交流阻抗、恒流放电等电化学测试，考察了在硫酸锰电解液中加入混合稀土金属氧化物以及采用不同的电沉积方式对MnO2电化学性能的影响。结果表明在电解液加入混合稀土氧化物并采用脉冲电沉积方式对改善MnO2的可逆性和提高放电容量等电化学性能有重要作用，为提高电解二氧化锰的可充性能研究奠定了基础。     

Research on determination of the rare-earth content in metal phases of steel

The behavior of the rare-earth dissolved in a-Fe, of the iron-cerium intermetallic compounds and of the rare-earth inclusions in electrolytic separation process has been studied by means of counting measurements of radioactivity, the electron probe, and X-ray analysis. The experimental results show that the rare-earth sulfide and the rare-earth oxide are stable completely in the electrolytic separation process, when the composition of the electrolytic solution is 1 pct 4-methyl ammonium chloride, 5 pct triethanolamine, 5 pct glycerin, and 89 pct methyl alcohol, and the controlling anode current density is ≤100 mA/cm². But Fe-Ce intermetallic compounds and the rare-earth dissolved in a-Fe enter into electrolytic solution as ions. When the cerium ion concentration in electrolytic solution is >7.87 X 10^-5 mol/liter electrolyte, precipitates of cerium hydroxide will be formed. When the inclusions are separated quantitatively, the electrolytic solution must be filtered by using a funnel with filter paper pulp thick up to 6 mm, and not be filtered directly with single filter paper. Samples without rare-earth were remelted and a radioactive isotope¹⁴¹Ce was added to the steel. Inclusions were separated by the electrolytic method in the nonaqueous solution. The counting of 14lCe in the electrolytic solution was measured. Thus the rare-earth content in the metal phases can be calculated. Experimental results show that the rare-earth content in the metal phases increases with the total rare-earth content in steel. The rare-earth content in the metal phases of the steel was also found to increase as the aluminum content in steel was increased. This method for determining the rare-earth content in the metal phases of steel is very sensitive. The sensitivity is 10^-6 pct.     

稀土添加剂在硬质合金中的应用研究

对国内含稀土元素的硬质合金10多年来的研制情况及稀土元素对硬质合金组织和性能的影响进行了概述。     

Removing oxide and sulfide inclusions from molten steel by filtration

On the basis of thermodynamic calculations indicating that rare-earth sulfide inclusions may form in molten nonalloyed structural steel, the influence of filtration on the content of sulfur, oxygen, and nonmetallic inclusions in the steel is investigated. It is found that filtration removes the oxide phase and oxygen from 30Л steel. There is no change in the content of sulfide inclusions and sulfur. Filtration of steel preliminarily treated with 0.05–0.30% rare-earth metals removes 10–60% of the sulfur. Metallographic data show that the content of both oxide and sulfide inclusions is reduced here. Gray impressions of filter templates show that the sulfur-bearing phase is removed by an adhesive mechanism: this phase adheres to the filter surface, forming continuous borders around it.     

Quantitative Analysis of Life Index of Electrothermal-Film Coated Ceramic Heating Elements with Rare-Earth Element Doped

For electrothermal-film heating elements for ceramics, the quantitative expression of the relation between the contents of multicomponent semiconductor dope and rare-earth element additive through the multivariate statistical regression analysis was presented, and the optimum control index of the multicomponent semiconductor dope and the rareearth element for the maximum life was also determined. The research shows that the life value ranging from 15 to 20 thousand hours can be ensured only if the evaluation grade of metal oxide dope in the compounding formula is controlled between grades 0.5 to 1.2. The relation of the content of multicomponent rare-earth element dope and the life index of electrothermal-film heating material for ceramics was determined theoretically.     

铝镁合金压铸用高性能稀土模具新材料 RE528的开发

本文从铝镁合金压铸用模具材料的性能要求入手,分析了常规模具材料的问题与不足,并以4Cr5W2VSi钢为基础,通过加入稀土元素和优化成分设计,成功研发一种具备优异冶金质量和组织性能、高附加值的稀土RE528热作模具新材料,其性能大大优于一般模具材料,具有良好应用前景。     

Rational design of novel carboxylic acid functionalized phosphonium based ionic liquids as high-performance extractants for rare earths

Developing the novel ionic liquids as the potential substitutes for conventional organic solvents in extraction of the rare-earth metals is highly desirable but challenges still remain. In this study, the well-designed carboxylic acid functionalized phosphonium based ionic liquids, (4-carboxyl)butyl-trioctyl-phosphonium chloride/nitrate, were synthesized and characterized. The as-prepared samples were tested as the undiluted hydrophobic acidic extractant for rare-earth metal ions, affording the maximal loading of 3 mol/mol towards Nd(III) in aqueous solution and the remarkable stripping performance. The results also reveal their excellent extractability and selectivity for Sc(III) in the mixtures of six rare-earth ions, as well as the outstanding separation properties between rare-earth and first row transition-metal ions (i.e., La/Ni, Sm/Co). Moreover, the extraction mechanism indicates that the extracted rare-earth complex via a proton exchange in the ionic liquid phase is structurally similar to the complexes obtained with neutral extractants. This work presents a prototype for the fabrication of the hydrophobic cation-functionalized ionic liquids for highly efficient rare-earth extraction and provides the future application in recycling of rare-earth metals from the spent magnets.