钽粉的低温掺氮及氮在钽中的分布

叙述了钽粉在镁还原脱氧后引入氮气对钽粉进行掺氮,在200℃以下0．1MPa以上,保温时间大于2h时,得到的钽粉粒子间含氮差别率在20％以下。用俄歇电子能谱仪对渗氮的钽表面进行元素分布研究,发现氮在钽中分布是不均匀的,对于每个粒子也是外表面氮浓度大于钽内部的氮浓度。     

电容器钽粉镁处理降氧工艺探究

本文探讨了钽粉镁处理降氧工艺:钽粉与还原剂镁粉充分混合,在真空或惰性气氛下800～950℃还原反应,出炉后酸洗除去残余还原剂等杂质。从加镁量、反应温度、反应时间、掺氮等参数分析影响降氧效果的各因素。通过对比试验得出:加镁量要稍过量,为钽粉含氧重量的300%为宜;反应温度在900℃以下降氧效果不明显,反应温度越高,降氧效果越好,但温度过高会减少钽粉比表面积,导致比容降低;反应时间需≥3h,时间过短反应不充分,达不到降氧效果;反应完后掺入杂质氮可以降低钽粉中氧含量,出炉前用一定比例的氧气钝化钽粉,可以增强降氧效果。并通过工艺实践,确定了镁处理降氧的最佳工艺参数。     

ONH836分析仪同时测定钽制品中氧、氮、氢含量研究

使用美国力可公司ONH836分析仪对钽丝、钽条、钽锭中氧氮氢量的测定方法进行探讨和研究,对样品中氧氮氢的释放功率、称样量等进行试验。确定测定钽丝、钽条、钽锭中氧、氮、氢量的最佳分析条件:分析功率4.8 kW;氧氮氢分析积分时间分别为40、70、50 s;称样量在0.10~0.15 g之间。在优化的条件下建立氧、氮、氢校正曲线,线性好,相关系数γ均大于0.999 0;测定钛标、钢标中氧、氮、氢标准物质,其测定值与认证值相吻合;测定氧、氮、氢质量分数分别为0.016%、0.002 6%、0.000 5%的样品其相对标准偏差RSD(n=11)分别为5.8%、8.0%、18.4%;并计算了测定的重复限性;确定氧、氮、氢的测定下限(5LOD)分别为0.001 0%、0.000 5%、0.000 5%。方法的准确度和精密度较好。     

脉冲加热-惰气熔融法同时测定钽、铌中氧、氮、氢量

应用Leco公司TCH600氧氮氢仪,脉冲加热-惰气熔融法对钽铌中氧、氮、氢量同时测定的分析条件进行试验和研究。试验结果表明,氧、氮、氢同时测定时的分析功率为4.6 k W;分析积分时间分别为40、70、45 sec;比较器水平分别为1.0%、1.0%、3.0%。在优化的条件下建立的氧、氮、氢校正曲线,线性好,相关系数均大于0.999 0;测定钛标、钢标、原冶金部行业铌粉中氧、氮、氢标准物质,其测定值与认证值相吻合;样品加标回收率在91.3%~105.0%之间;测定氧、氮、氢含量分别为0.004 8%、0.001 1%、0.000 5%的样品其相对标准偏差(RSD,n=5)分别为2.8%、10.4%、10.0%;氧、氮、氢的测定下限(5LOD)分别为0.001 0%、0.000 5%、0.000 5%。     

热处理温度对钽粉性能的影响

用钠还原氟钽酸钾得到的原粉分别在1350,1400,1450℃温度下进行热处理,得到的3种钽粉按照相同的条件进行镁还原脱氧处理,测试钽粉的化学成分、物理性能和电性能。表明提高热处理温度：可降低钽粉氧,钾,钠杂质含量,平均粒径和松装密度增大,细粉比例和收缩率降低,颗粒强度和坯块强度提高;在条件Ⅰ下赋能的钽粉比容、漏电流、损耗降低;在条件Ⅱ下赋能的钽粉漏电流和损耗降低,比容提高。因此,热处理温度低的钽粉适合在较低温度下烧结、低压赋能制作电容器;而热处理温度高的钽粉适合于较高温度烧结和较高电压赋能制作电容器。     

影响CAl型电容器钽片漏电系数的工艺因素

对影响钽片电容性能的主要因素进行了分析,并进行了各种条件试验和检测。指出钽粉的原始粒度、碳、氧含量的配比以及烧结温度、烧结时间等均对钽片的漏电系数有明显的影响。要根据原始钽粉中碳、氧及其他杂质的含量进行必须的氧含量计算,再配入适当的氧化钽,其次进行粉末粒度的配比,最后选择最佳烧结工艺,配用适当的润滑油进行轧制,可获得极为满意的优质钽片。     

铌粉中氧、氮定值

按国家标准样品定值的一般原则和统计方法对铌粉中氧、氮特性值进行均匀性检查和定值。采用脉冲加热-红外/热导法对铌粉中氧、氮进行测定,用极差法和F检验法对测得数据进行均匀性检查,均匀性好;对定值数据进行可疑值检验、正态性检验、平均值一致性检验、平均值等精度检验,检验结果均符合要求;定值中采用有证标准物质(CRM)校准仪器,使用的仪器通过国家计量核定,以确保量值的溯源性和准确性。计算氧质量分数标准值为0.301%±0.007%,氮质量分数标准值为0.028 0%±0.002%。     

脉冲红外和热导检测法测定钌粉和钌靶中氧、氮含量

建立了钌粉和钌靶中氧、氮含量的测定方法。研究了样品前处理、仪器条件、助熔剂选择、方法准确度和精密度等。以锡-碳作助熔剂,在选定条件下,采用脉冲红外和热导检测法,测定50×10^-6氧时RSD<10%,测定40×10^-6氮时RSD<25%;加标回收率:氧100%~102%,氮91%~101%。测定范围:氧0.002%~0.4%,氮0.0001%~0.02%。方法简便、快速、精密度和准确度满足质量控制要求。     

钽的氮离子注入法研究

实验研究证实,通过氮离子注入的方法对钽基材进行表面强化,可大大提高钽材的表层硬度及耐蚀性能。俄歇电子能谱及X射线衍射分析表明,Ta注入N~+后生成了新相TaN_(0.1)。     

锻造钽的性能及动态流动本构关系

为了解经挤压、锻造和热处理工序所得纯钽材的性能，对各工序钽材的化学成分、硬度、微观组织进行了检测。对挤压、锻造和热处理工序后钽材的力学行为进行了研究。应用Instron液压伺服试验机和分离式Hopkinson压杆对经锻造和热处理的钽材在不同温度不同应变率下的性能进行了试验。结果表明：（1）经初始挤压钽棒的氧和碳含量比原料粉高出约30％，但氮的含量比粉料下降50％以上；（2）再锻造后经过1523K，2h的退火处理，钽饼已完全再结晶。晶粒数和硬度沿钽饼中心到边沿变化；（3）挤压和锻造的钽饼中心处呈现明显的各向异性，这种性质随远离圆饼中心而变弱。基于热激活位错滑移机制以及塑性变形的物理概念，绘出了一个预测钽材塑性流动戍力的本构模型。通过与Johnson—Cook模型以及实验结果比较和分析可知，此模型可以较好地预测钽金属的塑性流动应力。     

Flake tantalum powder for manufacturing electrolytic capacitors

The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.     

钽中杂质元素分析的DCA全谱直读方法研究

原子发射光谱中直流电弧光谱技术在众多粉末材料的检测中具有许多其它技术难以企及的优势,本试验无需样品分解,直接将钽及其化合物转化为氧化物,配制系列氧化钽光谱标样,通过选择采用94%光谱纯碳粉同6%氟化钠混合做载体,15 A分析电流,运用载体分馏效应,用直流电弧阳极激发,电极中实现杂质元素与基体分馏,依据时序分析和扫描峰,确定元素分析波长、元素积分时间、背景扣除点,建立Ta中Fe、Al、Si、Mn、Mg、Ni、Ti、V、Co、Pb、Bi、Sn、Zr、Sb、Cu、Ca、Cr、Nb、Mo、Y、Ga、Ba、In、Ag、As、Re、Zn、Hf、Cd、Te等30种杂质元素同时测定的分析方法,测定范围0.3⁶00μg/g,加标回收率在93%600μg/g,加标回收率在93%¹15%之间,RSD在6%115%之间,RSD在6%²0%之间。     

钽粉等离子体球化及其球化过程中卫星粉的形成机制

微米级钽粉(Ta)在生物医疗增材制造和其它制造领域具有广阔的应用前景。采用射频热等离子体对不规则钽粉进行球化处理以改善其流动性,对等离子体球化处理前后的钽粉进行了表征,并分析了球化过程中卫星粉的形成过程与机制。结果表明,经等离子体球化后的钽粉具有较为理想的球形度和光滑的表面,其霍尔流动性和表观密度分别从13.6 s·(50 g)^-1提高到6.73 s·(50 g)^-1和6.83 g·cm^-3提升至9.06 g·cm^-3,钽粉的球化率和球形度分别可约达95.2%和0.92;球化过程中卫星粉的形成主要是因液滴的碰撞所致,且随着送粉速度的增加,液滴碰撞概率增大,液滴的凝并使球形颗粒的粒径增大。     

电容器用铌粉和钽粉制备技术的进展

综述了铌粉和钽粉的现行生产工艺及几种新的还原方法，介绍了金属热还原反应中的电化学反应机理。钽粉的现行生产工艺几乎都用亨特法，铌粉则大部分采用铝热还原法生产。通过对亨特法还原条件、稀释剂组成等各种工艺参数的改进，已经可以制备纯度高、形态可控的金属钽粉。铌粉新还原方法的研究主要包括金属预成形热还原法、镁等蒸气还原预成形氧化物粉末的方法、镁或钠的蒸气还原氯化物蒸气的气相还原法、以液氨为介质在低温液相中均相还原铌或钽的氯化物的方法、反应媒介熔盐在强搅拌条件下的液体镁热还原金属氧化物的方法等。     

The Corrosion Protection of Nickel Equipment in Chloride-Fluotantalate Melts

The possibility of corrosion protection of nickel equipment at 680–780°C in chloride-fluotantalate melts, used in the sodium-thermal production of tantalum capacitor powder, is investigated. It is shown that preliminarily adding tantalum powder (no less than 0.3 wt. % relative to K₂TaF₇) to the NaCl–K₂TaF₇ (ca. 14 mol %) melt prevents the nickel corrosion from starting just as the melt is fused; the electroless tantalum deposition on nickel starts, which results in the formation of a Ni₃Ta–Ni₂Ta intermetallic protective coating on the nickel surface. The effects of the exposure time and the melt temperature, as well as the tantalum powder content and dispersity, on the tantalum deposition are studied.     

Untersuchungen zur Ta-Beschichtung von Stahl durch Vakuumplasmaspritzen

Investigations of tantalum coatings on steel by vacuum plasma spraying In this work the possibilities of the production of tantalum coatings by vacuum plasma spraying were investigated. Suitable parameters of the vacuum plasma spraying process were determined, and the quality of vacuum plasma sprayed tantalum coatings was evaluated with regard to chemical composition, adhesion strength, density and corrosion behaviour. To obtain high-quality coatings it was necessary to apply sufficient plasma power as well as an optimal injection of spraying powder into the plasma torch. A complete melting of the tantalum powder particles could not he achieved. The coatings obtained showed a good adhesion strength but a low formability (ductility). The corrosion resistance against HCL and HNO₃ was evaluated by curves of the current density versus potential. With the aid of the passive current density it was determined that the corrosion resistance of the sprayed coatings was not as excellent as of compact tantalum. The increased surface roughness was not significant with respect to the corrosion behaviour. The reduced corrosion resistance could be caused probably by a high oxygen content of the tantalum powder, especially by oxides around individual powder particles. In contrast to tantalum, vacuum plasma sprayed titanium coatings showed the same corrosion resistance as compact titanium under the same testing conditions.     

Strength and ductility of powder consolidated ultrafine-grain tantalum

Bulk ultra-fine grain tantalum was successfully fabricated from pure tantalum powder particles with an average particle size of 50 μm by equal channel angular extrusion at 900° C and 1200° C using three different processing routes. The effects of extrusion route and temperature on the consolidation performance are evaluated through microstructural analysis and room temperature mechanical testing. The consolidated tantalum has a “wood grain” like structure with strong interparticle bonds and a grain size <100 nm. The lamellar structure is helpful in resisting crack formation and fracture. The bulk tantalum consolidates are much stronger than annealed wrought tantalum and have significant ductility. Tensile tests for consolidated tantalum at room temperature show a yield strength of 340–376 MPa, an ultimate strength of up to 618 MPa, and strains to failure of ~19–25%. These properties are comparable to wrought Ta. The present study demonstrates that equal channel angular extrusion is a feasible method for fabricating bulk nanostructured refractory alloys from precursor powder, with a combination of high strength and good ductility.     

钽粉颗粒强度的研究

研究了采用激光粒度分布仪测试电容器级团化钽粉粒度分布及强度的方法。其中心内容是:先采用3种不同比表面积、松装密度和费氏平均粒径的钠还原原粉,按3种烧结工艺制得团化钽粉。然后把烧结得到的6种试样加入纯水中,以200～300r/min进行高速搅拌并以40W,42kHz超声波振动。将激光衍射分析仪的激光束穿过经不同搅拌时间的悬浊钽粉,测得不同时间的钽粉粒径分布曲线。分析分布曲线可以获得团化钽粉的一系列信息,包括:①几种团化钽粉颗粒的相对强度;②影响团化钽粉颗粒强度的因素;③钽粉强度和其他性能如介电损耗、流动性,平均粒径及密度的关系等。     

氧含量对FFC法制备钽粉形貌和电容的影响

研究了FFC法制备钽粉过程中产物形貌的变化规律。结果表明,电解过程中,钽由高价氧化物向低价氧化物转变,由于钽的低价氧化物不稳定,与融盐中的金属离子结合生成块状钽酸盐中间相。当中间相中氧含量低到一定程度,钽酸盐中间相就会分解,最终获得原粉颗粒在200~400nm之间,以链状晶粒成单链连接分支形成的多孔基本团聚体。分析了不同电解时间所得钽粉的电性能。电解时间越长,电容越大。     

Quantitative analysis of phases formed in the aluminothermic reduction of Ta2O5 by plasma

A novel technique of aluminothermic reduction of tantalum oxide is developed to produce tantalum in form of powder. In this technique, hydrogen plasma is used to trigger the reaction in a plasma reactor. The reacted powders were analyzed by XRD and SEM. Rietveld method was used to quantify the phases present in the product of reaction. The results showed that a tantalum rich phase with a dendritic structure, typical of molten phases is formed. This phase occurred in significant amounts onto the surface and in bulk of the reacted grains.