钨粉粒度控制的回归方程

本文研究蓝色氧化钨氢还原的工艺参数对钨粉粒度的影响,结果表明,钨粉的F_(sss)粒度与还原温度、舟装料量等因素呈线性关系。实验数据用电子计算机处理,结果获得了预测和控制钨粉F_(sss)粒度的线性回归方程。     

钨及钨合金专利

—种仲钨酸铵自还原制备蓝色氧化钨的方法及装置；一种耐磨管状碳化钨焊条；一种高性能超细碳化钨粉的制备方法；一种高性能纳米级及超细钨粉的制备方法。     

氧化钨相成分对超细钨粉均匀性的影响

研究了通过传统氢还原工艺制备超细钨粉末过程中氧化钨原料相组成对超细钨粉均匀性的影响。结果表明：单一相组成的氧化钨能制得超细而均匀的钨粉,多种相组成的氧化钨,由于其在还原过程中存在不同的还原路径和还原速度,制得的钨粉虽细但不均匀。     

氧化钨氢还原机理研究进展

钨金属硬度高,熔点高以及耐磨性优良,抗电子迁移能力强,广泛应用于工业的各个领域.目前工业上制取钨粉的方法普遍为氧化钨氢还原法,该方法清洁简单,但由于影响因素的繁杂和氢分子的难以检测,其还原机理特别是氢还原氧化钨的动力学机理尚待研究,制取均匀粒度超细钨粉技术参数的确定也有待科研者的努力.本文总结了氧化钨的氢还原现阶段的热...     

蓝钨氢还原工艺及其还原机理的探讨

研究蓝钨氢还原工艺并分析了蓝钨在氢气还原过程中主要相成份的变化。实验结果表明:γ-氧化钨氢还原过程是制取超细钨粉的关键环节。     

液—固混料法制取钨—稀土氧化物包覆粉的研究

进行了以氧化钨为原料，稀土氧化物为掺杂相，用液－固混料法将掺杂与氧化钨混合，再经过盐类分解，氧化钨还原等工艺，制取不同掺杂相和掺杂量的钨－稀土氧化物包覆粉的研究，着重探讨了原料类型，还原温度及掺杂相对还原程度的影响。结果表明，以ＷＯ２．９为原料的包覆粉，综合性能好；随还原温度升高，粉末还原程度提高，掺杂相含量高的比含量低的难还原，三元系粉末比二元系粉末难还原，用液－固法制备钨－稀土氧化物包覆粉，其     

超细碳化钨制备关键技术及评价方法研究的新进展

从氧化钨原料、钨粉还原、碳化及评价方法等四个方面对超细WC制备关键技术进行综合评述。氧化钨原料的研究重点在于通过改善氧化钨的微观结构,从而提高超细钨粉的分散性和晶粒均匀性;在粒度可控的条件下提高钨粉晶粒生长的完整性,是超细钨粉还原过程最主要的研究方向;改善钨粉的分散性,提高钨粉与炭黑混合的均匀性及接触面积,提高超细碳化钨的结晶完整性并避免形成烧结团聚体是碳化阶段研究的重点;超细碳化钨团聚体微观缺陷分析、EBSD测量超细碳化钨真实晶粒度、合金晶粒度表征超细碳化钨粉末粒度均匀性等是目前超细碳化钨评价方法研究的重点。     

氧化钨的形貌结构对纳米WC粉末均匀性的影响

研究了在传统氢还原工艺制备纳米碳化钨粉末过程中不同氧化钨的形貌结构对纳米W/WC粉末均匀性的影响,并对粉末及其WC-Co烧结体的性能进行了表征。结果表明,用具有疏松、多孔形貌结构的细小氧化钨颗粒更容易制备出结构较疏松、分散性较好的纳米W粉和WC粉。晶粒聚集和异常粗大颗粒的产生,主要与碳化过程中团聚纳米钨粉颗粒因烧结合并增粗有关。     

电感耦合等离子原子发射光谱法测定稀土系贮氢合金中镍、镧、铈、镨、钕、钐、钇、钴、锰、铝、铁、镁、锌、铜分量

将稀土系贮氢合金试样经硝酸、盐酸分解,在酸性介质中,用电感耦合等离子发射光谱仪测定镍、镧、铈、镨、钕、钐、钇、钴、锰、铝、铁、镁、锌、铜分量。通过样品处理条件的选择、波长的选择、干扰试验等条件实验,建立了可实现多元素的快速测定稀土系贮氢合金中镍、镧、铈、镨、钕、钐、钇、钴、锰、铝、铁、镁、锌、铜分量的分析方法。     

不同氧化钨原料对钨粉性能的影响研究

对还原过程中不同氧化钨原料对钨粉性能的影响进行了研究,进一步探索了原料物理性能与钨粉性能的影响关系,为根据不同钨粉性能要求而针对性地选择所用原料提供了依据,对生产高质量的钨粉具有重要指导意义。     

稀土La在纳米晶（W, Ni, Fe, La）复合粉末烧结过程中的作用机理

采用溶胶-喷雾干燥法制备纳米晶(W,Ni,Fe,La)复合粉末,研究了粉末在烧结过程中La对抑制鼓泡和晶粒长大的作用机理,通过XRD与SEM分析了La在烧结过程中的相转变规律和在合金中的存在形式,讨论了稀土La对合金液相烧结过程中扩散的影响。结果表明:稀土La在纳米复合粉末中主要以La2WO6与La4W2O15的形式存在。经液相烧结后,稀土La主要以二次相颗粒的形式分布于粘结相中,生成高温下能稳定存在的La4W2O15相,该相对杂质元素Ca、O具有很好的亲和力,起到晶界净化和晶内净化的作用。同时二次相颗粒存在于粘结相中,抑制了W在粘结相中的扩散,降低了W在粘结相中的溶解度,使得液相烧结溶解-析出过程减慢,从而抑制液相烧结阶段的晶粒长大和鼓泡现象。     

Development of tungsten heavy alloy reinforced by cubic zirconia through liquid-liquid doping and mechanical alloying methods

A new tungsten heavy alloy, which is characterized by fine yttria stabilized cubic zirconia (c-ZrO₂(Y)) particles dispersed in the alloy, was developed by an ion-level liquide-liquid (L-L) doping technique combined with mechanical alloying. The microstructure and mechanical properties of tungsten heavy alloy were investigated, and the formation process and role of zirconia were discussed. Results show the zirconium element transforms in an order of Zr⁴⁺ to Zr(WO₄)₂ or 2Zr(WO₄)₂ nH₂O to m-ZrO₂ in the preparation process of powders. Finally, the c-ZrO₂(Y) particles with size of 200–1000 nm are obtained in tungsten heavy alloy during sintering at 1520 °C for 90 min. Most of c-ZrO₂(Y) particles are distributed within tungsten grains, and some c-ZrO₂(Y) particles tend to be dispersed at the interfaces of tungsten grains, while a small number of c-ZrO₂(Y) particles are dispersed in γ(Fe, Ni, W) matrix. The compressive strength of new alloy is improved approximately 8.2% than that of 93 W-4.9Ni-2.1Fe. This attributes to c-ZrO₂(Y), which refines tungsten grain, lowers W-W contiguity and strengthens tungsten and γ(Fe, Ni, W) grains.     

W-1%La2O3合金的显微组织分析

通过X射线衍射仪、光学显微镜、扫描电镜、透射电镜对聚变堆面向等离子体候选材料W-1%La2O3合金的显微组织进行了研究。结果表明:与纯钨相比,添加了1%La2O3的钨合金组织致密,孔隙与晶界裂缝消失,大量颗粒弥散在钨合金基体上。进一步的化学成分分析并结合电子衍射花样发现,在这些颗粒中不仅存在La2O3以及钨的氧化物,还存在一种镧的钨酸盐La2(WO4)3及非晶态颗粒。同时讨论了W-1%La2O3合金的韧性和存在颗粒的可能形成过程。     

Preparation of Al2-xYxW3O12 powders by citrate sol-gel process

Al2-xYxW3O12 （x=0.2, 0.5, 0.8, 1.0, 1.2, 1.5, 1.7 and 2.0） powders were synthesized by citrate sol-gel process. The concentration of species in a citric solution for preparing Al2-xYxW3O12 powders was calculated. The powders were characterized by differential thermal analysis（DTA）, thermogravimetry（TG）, X-ray diffractometry（XRD） and scanning electron microscopy（SEM）, respectively. No solid solution of Al2-xYxW3O12 is formed with x values varying from 0 to 2.0. The maximum solid solubility of Y2O3 in Al2W3O12 and Al2O3 in Y2W3O12 is less than 0.5. Y2W3O12 easily absorbs water in air and forms a composition of Y2W3O12·3.2H2O, and Al2W3O12 forms Al2W3O12·0.17H2O in the same condition.     

TUNGSTEN ELECTRODES CONTAINING THREE TYPES OF RARE EARTH OXIDES

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可加工AlN-BN复合陶瓷的制备

以碳热还原法合成的 AlN 粉末和市售 BN 粉末为原料,添加 5%Y2O3 为烧结助剂,利用无压烧结制备 AlN-15BN复合陶瓷,研究了烧结温度对 AlN-15BN 复合陶瓷相变、致密度、微观结构以及性能的影响,结果表明:Y2O3 可与 AlN粉末表面的 Al2O3 发生反应生成液相促进烧结,随着烧结温度的升高,复合陶瓷的致密度、热导率和硬度逐渐增加,片状的 BN 形成的卡片房式结构会阻碍复合陶瓷的收缩和致密。在 1 850℃烧结 3 h,可以制备出相对密度为 86.4%,热导率为104.6 W?m-1?K-1,硬度为 HRA56.2的 AlN-15BN复合陶瓷。研究表明,通过添加加工性能良好的 BN制备可加 AIN-BN复合陶瓷,是解决 AIB 陶瓷复杂形状成形问题的一个重要途径。     

Synthesis and characterization of nanocrystalline Ni produced by cryomilling in liquid nitrogen

NanocrystaUine Ni powders were successfully fabricated by mechanically milling at cryogenic temperature （cryomilling） with 1 wt.%Y2O3 particles. The experimental results have shown that the Ni grain size is reduced to 25 nm after 2 h of cryomilling in the presence of the Y2O3 particles. The cryomiUed Ni/Y2O3 powders can maintain their nanocrystalline structure up to 900℃, or 62% of the melting point of Ni. A bulk nanocrystalline Ni/Y2O3 material with a thermally stable grain size of approximately 100 nm was produced by cryomilling, cold isostatic pressing, followed by hot isostatic pressing. The microhardness of bulk nanocrystalline Ni/1wt.%Y2O3 is 315 DPH, which is two times as high as that of conventional Ni.     

Effect of rare earth La_2O_3 on the microstructure and mechanical properties of TiC/W composites

In this study, La2O3 was investigated as an additive to TiC/W composites. The composites were prepared by vacuum hot pressing, and the microstructure and mechanical properties of the composites were investigated. Experimental results show that the grain size of the TiC/W composites is reduced by TiC particles. When 0.5 wt.% La2O3 is added to the composites, the grain size is reduced further. According to TEM analysis, La2O3 can alleviate the aggregation of TiC particles. With La2O3 addition, the relative density of the TiC/W composites can be improved from 95.1% to 96.5%. The hardness and elastic modulus of the TiC/W 0.5 wt.% La2O3 composite are little improved, but the flexural strength and the fracture toughness increase to 796 MPa and 10.07 MPa·m1/2 respectively, which are higher than those of the TiC/W composites.     

稀土Y在90W-7Ni-3Fe合金中的存在形态和分布特征

以喷雾干燥法制备的不同稀土Y含量的90W-7Ni-3Fe复合粉末为原料,在不同的烧结温度下制备出不同稀土含量的钨合金,采用XRD、SEM和EDX研究了稀土Y在90W-7Ni-3Fe合金中的存在形态和分布规律。结果表明:稀土Y以Y2O3的形式存在于合金中,且钨颗粒内部未发现稀土Y的存在。Y的添加量为0.4%时,以富Y颗粒的形式分布在钨颗粒与粘结相之间;当添加量为5%时,在粘结相中形成了富Y区域。添加稀土Y可以有效地细化钨颗粒。     

EFFECTS OF Y2O3 AND CeO2 ON PROCESSING AND CHARACTERISTICS OF TUNGSTEN ELECTRODES

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