冷等离子体冶金中的粒子输运现象研究

介绍了冷等离子体冶金效应的实验方法和结果，列出了反应粒子的输运方程，较详细地分析了它们之间的耦合关系．在讨论输运方程的求解过程中，证明各种粒子的输运速率是与提纯效果紧密相关的．提供了对硅的提纯结果和工艺参数。

等离子体冶金的现状与发展

冶金工业作为国民经济发展的支柱,常见的冶炼技术有火法、湿法、电渣重熔、电子束熔炼和等离子体冶炼。等离子体具有热性能高、能量集中、化学活性高、冷却速度快和反应气氛可控等特点,已广泛的应用于熔炼、精炼和表面冶金。本文综述等离子技术在熔炼、精炼和表面冶金等领域的研究进展。其中,等离子体技术在熔炼和精炼中具有产品纯度高、功率可调、气氛可控、转化率与热利用率高和环境友好等优势;等离子体技术在表面冶金中具有涂层微观组织稳定、可获得传统工艺难以制备的合金层等特点。针对当下等离子体冶金技术存在设备寿命短、工艺参数难控制、成本高及国内冶金工业应用较少等问题,提出相应的解决策略和分析。并指出优化等离子体设备的设计,提高自动化水平;结合等离子体数值模拟等手段找到最佳工艺参数,在提高生产过程稳定性和产物品质的同时降低能耗和维护成本以及开发更大功率的大型等离子体炬,实现等离子体技术在冶金工业中的大规模应用为未来的研究重点。最后,对等离子体冶金技术的发展方向进行展望。

铂族金属二次资源等离子体冶金产物的物相分析

研究了题示冶金产物（铂族金属富集物）中的快冷物相。主体物相是以Ｆｅ或（Ｆｅ，Ｎｉ）为基体含铂族金属（ＰＧＭ）的合金固溶体相。含Ｐｔ量高的富集物中有（Ｐｔ，Ｐｄ）固溶体相，含Ｓｉ量高的富集物中有赋存ＰＧＭ的Ｆｅ或Ｎｉ的硅化物相；微量Ｓｎ除分布在众多的相中外，与ＰＧＭ生成锡化物相。发现急冷合金化可生成εＦｅ亚稳相、ＦｅＣ亚稳相。各物相中除主体成分外，都含有众多的组元。快冷ＰＧＭ富集物是多种非平衡物相的集合体。

冶金新能源——等离子体

冶金用等离子体即"气体电弧",具有良好的导电性,能量集中,电弧稳定,电效率和传热效率高。电弧等离子体发生器装置及其附件用于连铸的中间包加热,装机功率达1000kW,耗电5～10kWh/t钢;用于烧结机点火,功率为800kW/h,兼收烧结产量可提高5%。

提高粉粒沉降过程中等离子体纯化能力的研究

限于工艺条件 ,我们过去曾得出粉粒在等离子体中沉降时 ,提纯效果可忽略不计 ,本文经过详细的分析、计算和论证表明 ,沉降时间及提纯速率可经工艺改进而提高到使提纯效果达到决定性的地步。文中提供了计算结果、改进措施及粉粒可收集的判据。这对于提高等离子体总的冶金效应和将其推向应用都具有很大的意义。

微波脱硫等离子体冶炼高冰镍

一种等离子体冶金直接获取高冰镍的方法，铜、镍氧化矿通过预处理以及脱硫工序得到焙砂，焙砂再经过冶炼得到高冰镍。其特征在于：冶炼过程在一等离子冶金炉内进行，其主要由等离子体电源、喷枪、反应塔、熔池、烟道等部分组成；冶炼过程及技术条件是：等离子冶金炉经过烤炉至1500℃引弧，将含硫4％～8％，粒度-180目的焙砂及石英石打入温度5000—6000℃的反应塔内等离子中温区，物料瞬间即熔并完成化学反应后进入熔池澄清分离，熔池温度1800～2000℃；所处理的物料含镍Nj3％～10％、Cu2％-8％、S20％-27％。

Induction plasma spheroidization of tungsten and molybdenum powders

The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and the cross section of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed on the particle surface of these two metals. The influence of spray chamber pressure on the spheroidization and oxidation phenomena was discussed. The results show that fewer Mo particles than W particles are spheroidized at the same powder feed rate under the same plasma spray condition although molybdenum has a lower melting point. A small fraction of tungsten is evaporized and condensed either on the surface of tungsten particles nearby or on the wall of spray chamber. Tungsten oxides were found in tungsten powder processed under soft vacuum condition. Extremely large grains form inside some spheroidized particles of tungsten powder.

Tribological behaviors of Fe-Al-Cr-Nb alloyed layer deposited on 45 steel via double glow plasma surface metallurgy technique

Double glow plasma surface metallurgy technique was used to fabricate a Fe?Al?Cr?Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of th?eA Fl?eCr?Nb alloyed layer were analyzed by scanning electronic microscopy, X-ray diffraction and energy dispersive spectroscopy. The results indicate thatthe 20 μm alloyed layer is homogeneous and compact. The alloyed elements exhibit a gradient distribution along the cross section. Microhardness and nanoindentation tests imply that the surface hardness of the alloyed layer reaches HV 580, which is almost 2.8 times that of the substrate. Compared with the substrate, the alloyed layer has a much smaller displacement and a larger elastic modulus. According to the friction and wear tests at room temperature, the? FeAl?Cr?Nb alloyed layer has lower friction coefficient and less wear mass, implying that the Fe?Al?Cr?Nb alloyed layer can effectively improve the surface hardness and wear resistance of the substrate.

Microstructure and compressive deformation of hypereutectic Al-Si-Fe based P/M alloys fabricated by spark plasma sintering

Al-Si-Fe based alloys are attractive light-weight structural materials for automotive engine components because of their high wear resistance, low density and low thermal expansion. Al-17Si 5Fe-2Cu-lMg-lNi-lZr alloys were produced in compact form by a spark plasma sintering （SPS） technique using gas atomized powders. The mean grain size of the compact was 530 nm, and fine equiaxed grains and uniformly distributed precipitates were observed in the compact. The compressive deformation behavior of the SPSed materials was examined at various temperatures and strain rates. All the true stress-true strain curves showed steady state flow after reaching peak stress. The peak stress decreased with increasing test temperature and decreasing strain rate. In the deformed specimens, the equiaxed grain morphology and the dislocation microstructure within the equiaxed grains were observed. These facts strongly indicated the occurrence of dynamic recrystallization during high temperature deformation of the present alloy.

自钝化W-Cr-Y合金层的制备及其抗氧化性能

为防止或缓解钨氧化,用双辉等离子体表面冶金技术在纯钨基材表面制备了W-Cr-Y自钝化合金层。采用扫描电镜(SEM)和X射线衍射仪(XRD)对合金层的组织和相结构进行了分析,并在模拟发生核聚变发电站冷却失效事故时的高温大气环境下对合金层的抗氧化性能进行了研究。结果表明,制备温度为800、900、1000和1100℃时,均成功地在纯钨表面形成了由W(Cr, Y)固溶体构成的厚度超过20μm的W-Cr-Y合金层。制备温度为1000℃时合金层厚度达到了35μm,表面光滑致密,合金层与纯钨基体呈现良好、无缺陷的冶金结合。制备温度较低(800℃和900℃)时,合金层在1000℃氧化10 h后的表面未形成连续的自钝化合金层,抗氧化性能较差。制备温度较高(1000℃和1100℃)时,合金层在氧化后形成了致密平整的氧化层,且制备温度为1000℃时合金层氧化后的质量增加最小,抗氧化效果最优。