Electrowinning molybdenum and tungsten

Projected long-range requirements for molybdenum and tungsten indicate that a new reduction technique is needed, and this article discusses research on one such method.     

Properties of porous materials of copper and nichrome fibers

Luginy Machine Building Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 46–48, April, 1992.     

Titanium carbonitrides in steels alloyed with tungsten and molybdenum

Conclusions The possibility of tungsten dissolving in titanium carbonitride present in the steel is confirmed by two factors: 1) the solubility of tungsten in titanium carbide, established in the binary WC-TiC system [4–7]; 2) the existence of four phases with the same type of structure and similar lattice constants in the Ti–W–C–N system (a=4.33 Å for TiC,a=4.24 Å for TiN,a=4.27 Å for W₂C,a=4.126 Å for W₂N [7]).Considering the affinity of tungsten and molybdenum and their interchangeability in carbides of other types, one would expect partial replacement of titanium, with molybdenum in carbonitrides. The solubility of tungsten and molybdenum in titanium carbonitride was demonstrated in two steels of different types — austenitic steel 417455 and pearlitic steel T 67. In steel T60 with 13% Cr, however, neither tungsten nor molybdenum was found in the carbonitride. Consequently, it can be assumed that the solution of tungsten and molybdenum in Ti(C, N) is also determined by the properties of the metallic matrix and the treatment or primary cooling conditions of the steel. This determines whether or not tungsten or molybdenum partially replaces titanium in carbonitride.Skoda, Pilsen, Czechoslovakia. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 60–62, September, 1978.     

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.     

The hardness and corrosion resistance of nickel alloys with molybdenum and tungsten

Conclusions The newly-developed Ni–Mo–W corrosion resistant hard alloys (N65M20V15 and N55M20V25) have a corrosion rate of no more than 0.2 mm/year in 30% HCl at 60°C and in 70% H₂SO₄ at 90°C, with a hardness as high as HRC 52.The alloys are precipitation-hardening. To obtain a high hardness it is recommended that they be heat treated by water quenching from 1000–1050°C and aging at 800°C for 4 h.Deceased.Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 24–27, March, 1972.     

铁盐沉淀法分离宏量钨钼(英文)

为了开发宏量钨钼分离的低成本方法,研究不同工艺条件对硫酸亚铁沉淀分离钨钼的影响。结果表明:钨钼分离的最佳反应温度为10℃,在此温度下反应时间大于7h后钨钼的分离系数不再增加;沉淀剂溶液的慢速加入可提高分离效果;当溶液中n(H+)/n(W)低于1/1时,往中性溶液中添加酸对分离过程有利;当溶液中铵浓度不高于3mol/L时,钨的沉淀率高,分离系数也较大。本方法可有效处理含一定杂质的工业溶液。这些结果表明铁盐在工业上用于钨钼分离的潜力大。     

Mechanically activated reactive synthesis of refractory molybdenum and tungsten silicides

In this study, processing of elemental powders mixtures was carried out by mechanical alloying (MA) and heat treatment in vacuum at 700–1000 °C for 1 h. The phase transformation of the powders was investigated by X-ray diffractometer (XRD). The results showed that mechanical alloying promoted the formation of a solid solution of elemental powders. The energy stored in the powders was increased as a result of exterior energy and the barrier energy of the formation of the compound could be exceeded easily. Intermetallics of MoSi₂, WSi₂, Mo₅Si₃, Mo₃Si and SiC/MoSi₂ composite powders were synthesized by mechanically activated reactive synthesis (MARS). The mechanically induced self-sustaining reaction was observed in MoSi₂ and MoSi₂ + 10 wt%SiC stoichiometry system. It has concluded that mechanically activated reactive synthesis is an effective method for the preparation of high melting-point refractory compounds.     

Brazing porous tungsten and molybdenum using palladium and titanium foils

Dissimilar brazing porous W and Mo using the Pd and Ti foils have been investigated in the study. Successful brazed joints are obtained from using the Pd filler foil. Brazed joints are fully dense and free of any intermetallic phase. Meanwhile, infiltration of the Pd-rich melt into the porous W substrate is trivial, limited below 30 μm for the specimen brazed at 1610 °C for 600 s. The application of Pd filler metal shows great potential in brazing porous W and Mo for impregnated dispenser cathode application.     

采用TRPO从过氧化氢溶液中萃取钼和钨的数学模型和反应机理（英文）

为了解利用三烷基氧化膦(TRPO)从过氧化氢溶液中萃取钼和钨的化学行为,采用斜率法、拉曼和红外光谱研究钼和钨的萃取反应机理。通过建立数学模型,获得钼或钨的萃取分配比(D_Mo或D_W)关于平衡pH值、TRPO浓度和温度等变量的经验公式,并进一步在H⁺-W-Mo-H₂O₂溶液中验证经验公式的可靠性。结果表明:经验公式计算的D_Mo或D_W和实验值吻合度良好。实验条件下,20℃时钼和钨的萃取平衡常数分别为K_Mo^app=8.51×10³(0.74≤pH_e≤1.70)、K_Mo^app=99.89×10³(1.7e≤4.62)和K_W^app=2.65×10³(0.92e&l...     

利用D309树脂离子交换分离宏量钨和钼

基于钨、钼在水溶液中聚合能力的差异,提出一种利用D309树脂离子交换分离钨、钼的新方法。静态实验表明,分离钨、钼的最佳pH值为7.0,最佳接触时间为4 h,钨、钼分离系数达到9.29。等温吸附过程研究表明,D309树脂对钨、钼的吸附分别属于Langmuir模型和Freundlich模型。吸附动力学研究表明,D309树脂对钨的吸附属于内扩散控制。对于含70 g/L WO3和28.97 g/L Mo的料液,经动态吸附分离钨、钼后,所得流出液中Mo与WO3的质量比达76,所得解吸液中WO3与Mo的质量比达53.33。