稀土在离子渗氮中的氧化对催渗效果的影响

利用Ｘ射线衍射仪和扫描电镜研究了稀土催渗离子渗氮过程中,稀土与氧之间的作用对催渗效果的影响。结果表明：用新稀土块进行催渗时,稀土易与渗氮气氛中的氧结合,使气氛中的大部分氧被清除,大大削弱了氧对不参氮的阻碍作用,提高了渗速,稀土遥这种除氧作用是稀土催离子渗氮的又一重要原因,用过的旧稀土块催渗效果差,原因是在其表面形成了一怪厚的氧化物,使稀土的催渗作用不能充分发挥,若将这层氧化物剥去后再使用,稀土的催     

钢中稀土对化学热处理的影响与作用机理

介绍了钢中稀土对离子氮化、离子硫氮碳共渗及气体渗碳的影响，提出了钢中稀土促渗的“气团－通道”模型。指出稀土是通过直接和间接作用来加速氮、碳的扩散与氮、碳化物的形成。因此，钢中稀土具有显著的促渗作用，并提高渗层硬度。     

稀土含量对38CrMoAl钢渗氮层性能的影响

为了克服38CrMoAl钢渗氮速度慢,渗层脆性大,稀土添加到渗氮气氛中只能作用于工件表面等缺点,研究了38CrMoAl钢中不同稀土添加量对渗氮层性能的影响,并初步分析了其影响机制。研究结果表明：稀土对38CrMoAl钢渗氮具有明显的催渗作用,且能提高渗层性能。原因是稀土加入钢中后,引起周围铁原子的点阵畸变,有利于氮原子的吸附和扩散,且稀土易与渗氮气氛中的氧结合,削弱了氧对渗氮的阻碍作用;同时稀土的晶粒细化、固溶体强化、微合金化也是其改善渗层性能的重要原因。     

稀土在化学热处理中的作用机理

综述了１０几年来稀土在化学热处理中作用机理的研究状况,从稀土渗入工件表面,稀土催渗与稀土对渗层组织的作用三方面作了讨论,总结了稀土元素作用于化学热处理的全过程,并提出了该领域研究的发展方向。     

稀土催渗下的45钢固体渗硼工艺研究

采用固体粉末渗硼法对45钢基体表面进行稀土催渗下的渗硼实验.通过金相和X射线衍射研究了渗硼后的物相组成和组织演变,讨论了渗硼过程中的硼化物形成动力学和稀土催渗硼机理.结果表明,45钢在稀土-硼共渗下可形成连续单一的Fe2B相硼化物;渗硼层组织致密,硼化物齿呈现直长而细密地垂直楔入基体的形貌特征,与基体牢固结合;稀土能对渗硼过程起到催渗作用,使渗硼速度加快,渗硼层厚度增加,但存在一个最佳稀土添加量,使渗硼催渗效果最好;稀土催渗作用是稀土对渗硼渗剂产生催化作用和对基体表面活化作用的综合结果;硼化物形成动力学符合抛物线规律,随渗硼时间延长,渗层厚度先快速增加,后缓慢增加.     

固体硼铬稀土共渗组织与性能研究

研究了固体硼铬稀土共渗工艺、共渗层成分、组织和性能,并与单一渗硼层进行了比较。结果表明,硼铬稀土共渗改善了渗层组织,较大幅度地降低了渗层脆性,提高了渗层的抗疲劳磨损性能,稀土具有与单一渗硼时相同的催渗作用。还对共渗层中铬含量较少但分布均匀的原因进行了初步的分析。     

稀土盐浴渗钒的研究

研究了稀土对盐浴渗钒工艺及渗层某些(?)能的影响。结果表明,渗钒剂中添加稀土元素具有明显的催渗作用,渗钒速度约提高28%;稀土渗钒渗层的耐磨性、耐蚀性和抗氧化性均有所提高。稀土通过增大渗剂钒势、活化钢的表面、降低碳原子扩散激活能来提高渗钒速度。     

球铁曲轴稀土催化气体氮碳共渗

研究了稀土对球铁曲轴气体氮碳共渗工艺及渗层硬度分布的影响。结果表明：稀土有明显的催渗作用,共渗时间可缩短30％;稀土催渗后,渗层硬度梯度趋向平缓．应用效果表明：稀土催渗的球铁曲轴使用寿命提高10％。     

稀土,钛对渗硼层组织和性能的影响

研究了不同的稀土硼钛共渗处理工艺及其对组织和性能的影响。和纯渗硼层相比,发现共渗层具有高的显微硬度和低的硬度梯度、高耐磨性和热疲劳性;渗层组织致密,与基体结合良好。结果表明,稀土和钛对渗硼层具有明显的改性作用,同时发现稀土在三元共渗中具有明显的催渗作用,可使渗速提高３０％ ～５０％ 以上。根据工艺和性能得出稀土最佳浓度为３％ ～４％ ,ＴｉＯ２ 为４％ 。     

稀土在渗硼及硼的复合渗中的作用

本文综述了近十几年来稀土在渗硼及硼的复合渗中的作用以及稀土对渗层组织性能的研究概况，并对其作用机理作了初步探讨。     

Effects of rare earths in borax salt bath immersion vanadium carbide coating process on steel substrate

Various amounts of FeSiRe23, which were used as reducing agents, were added into typical borax salt bath used in thermal diffusion (TD) process to explore the effects of rare earths on borax salt bath vanadizing process and microstructure and properties of vanadium carbide coating. The effect results of rare earths on coating thicknesses at different process conditions showed that the right amount of rare earths could greatly accelerate vanadizing rate and that the accelerating effect worked mainly at the initial stage of TD process and decreased with increasing thickness of vanadium carbide layer. Moreover, the comparison of diffusion activation energies at various temperatures revealed that rare earths have optimal accelerating effect at 950 °C or so. The effect results of rare earths on coating microstructure and properties showed that the addition of rare earths into the borax salt bath can decrease grain size and improve fragility of vanadium carbide coating but decrease coating microhardness. And the electron probe microanalysis (EPMA) revealed that the addition of rare earths could decrease carbon concentration in the coating.     

Inoculating an Al-Si alloy with phosphorus,rare earths,sulfur

This paper describes an Al-23Si alloy that was inoculated with coinoculants containing phosphorus, rare earths, and sulfur. The results show that coinoculants containing phosphorus and sulfur, phosphorus and rare earths, and rare earths and sulfur can refine primary crystal silicon and modify eutectic silicon in hypereutectic Al-Si alloys. Further, it seems that the refinement effect of the rare earths and sulfur coinoculant is better than that of the other tested coinoculants.     

稀土、锶复合添加对AM60镁合金组织和性能的影响

稀土、锶复合添加对AM60镁合金组织、力学性能和抗热裂性能的影响的研究结果表明,往AM60镁合金中添加稀土后,稀土与合金中的异质形核核心Al9Mn11相或Al(8Fe,Mn)5相反应生成Al-RE-Mn三元相,减少了合金熔体中异质形核核心的数目,从而引起了合金晶粒粗化。往AM60镁合金中复合添加稀土和锶后,锶能够消除稀土引起的晶粒粗化作用,减少晶粒粗化对合金力学性能和抗热裂性能的不利影响,从而提高合金的高温屈服强度,并消除稀土对合金抗热裂性能的恶化作用。     

混合稀土对碱性介质中铝阳极性能的影响

采用交流阻抗、恒电流集气等电化学方法对比了含与不含混合稀土铝合金在4 mol/L KOH溶液中的阳极行为，并结合金相显微镜、电子探针等表面分析技术探讨了混合稀土元素对铝阳极性能的影响.结果表明:稀土使铝阳极的晶粒细化，阴极相减少，溶解均匀性增强，自腐蚀析氢量减少，性能得到优化.     

Processing of rare earth concentrates

The paper describes process details for extraction of rare earths from an intermediate grade concentrate of Madhya Pradesh region in India and a South African slag. The xenodme concentrate obtained from the former place was an intermediate grade （47%） rare earth phosphate containing both monazite and xenotime. The South African slag was a low-grade waste product typically containing only 4% of rare earths. The rare earth resource concentrates have been treated individually by different methods such as alkali fusion and alkali leaching to convert them into their mixed oxides. Both types of materials have been processed and greater than 98% solubilization of metal values has been achieved in the intermediate grade xenotime and 80% from the South African slag. The residue of xenotime hydroxide has been washed thoroughly to collect the sodium phosphate, as by-product and the slurry pH have been adjusted to separate rare earths from thorium effectively. Other impurities such as uranium and iron have been removed by precipitation of rare earths by oxalic acid. It has been possible to recover 〉95% yttrium along with other rare earth oxides.     

中国灯用稀土荧光粉行业的发展现状

介绍了我国灯用稀土荧光粉行业的现状及存在的主要问题，阐述了提高灯用荧光粉质量的途径，并对稀土荧光粉的发展趋势提出了建议。     

稀土永磁电机的应用现状及其发展趋势

详细介绍了稀土永磁电机的原理、现状和发展概况。指出发展稀土永磁电机是21世纪电机工业技术的发展趋势,而稀土永磁电机也正向大功率化、高功能化和微型化方向发展。     

Technology development for rare earth cleaner hydrometallurgy in China

China is the global leader in rare earth(RE)production using hydrometallurgical processes. Advantageous extraction techniques of rare earths from Baotou mixed rare earth minerals, bastnaesite, and ion-adsorption clays of rare earth deposits have been developed in China.The separation and purification technologies have also achieved rapid development. The industrial application processes for rare earth hydrometallurgy were summarized in the present paper. With the large demands and rapid development of rare earths, the issues of resources and environment are more prominent. This review gives an overview of the main processes that were developed in the past toward greener hydrometallurgy of rare earths in China. Based on the development of the rare earth industry,comprehensive utilization and cleaner production should still be focused on in the future, to support the sustainable development.     

添加富铈稀土对低锑合金结构及电化学性能的影响

应用线性电位扫描、计时电势分析法、交流伏安法和腐蚀质量损失法研究在含砷锡的低锑合金中添加混合稀土(85?,10%Y,3%La)对合金性能的影响,利用金相显微镜观察合金的微观组织。结果表明:富铈稀土能细化铅锑合金晶粒,薄化晶界,减少晶体缺陷,降低整体腐蚀速度和腐蚀的危害性;富铈稀土能抑制阳极膜中的PbO生长,生成的PbO也易于还原,降低阳极膜的阻抗,提高板栅合金的深循环性能;当富铈稀土含量为0.5%时,铈与铅生成金属间化合物(PbxCey),锑在合金中分布均匀。