一种钽靶材织构评价方法的模型构建

研究了一种钽靶材织构评价方法模型,关注{100}、{110}、{111}三种面织构的组份含量和分布均匀性,并对三种织构进行了定义,规定晶界角度定义为≤2°,组份含量取与标准织构取向差小于15°的晶粒的百分含量;同时,对取样方法与测试方法进行了规定,依据本模型,可通过织构分布折线图、15°取向图和IPF图来对钽靶材单点与整靶织构分布情况进行综合评价。     

直流电弧发射光谱法测定铌及铌合金中钽含量

采用直流电弧光谱仪对铌及铌合金中钽元素进行检测。通过试验确定满足分析条件的缓冲剂、样品与缓冲剂的配比及钽元素谱线并检测其精密度、准确度及检出限。结果表明,选择Li2CO3与碳粉1∶6混合作为缓冲剂,缓冲剂与样品比例为1∶2,钽元素的谱线为271.013 nm;加标回收率为94%~109%,测定值的相对标准偏差(测10次)均小于10%。     

JY Ultima2ICP-OES光谱仪测定Ta-2.5W和Ta-10W中钨元素的分析方法研究

采用发射光谱仪建立发射光谱法测定Ta-2.5W和Ta-10W中钨含量的方法。使用高纯氢氧化钽基体的纯钨标准溶液制作工作曲线,钨的分析线为209.475 nm,方法的线性范围为1.25%~15.00%,加标回收率在93.0%~99.0%之间,测定结果的RSD值(n=11)小于0.8%。     

Synthesis of TaB2 powders by borothermal reduction

Borothermal reduction processes of Ta₂O₅ with boron under vacuum were investigated. Ta₂O₅ reacted with boron to form various borides (TaB₂, Ta₃B₄, and TaB), depending on the boron/Ta₂O₅ molar ratio and temperature. In order to prepare pure TaB₂ powders, two routes were developed. The first route was one‐step heat treatment at 1550°C. With boron/Ta₂O₅ molar ratio of 9.0, pure TaB₂ powders with strong agglomeration were synthesized by the first route, and the particle size and oxygen content were 0.7 μm and 0.9 wt%, respectively. The second route consisted of two‐step heat treatment at 800°C and 1550°C plus intermediate water washing. With lower boron/Ta₂O₅ molar ratio of 8.2, pure TaB₂ powders with less agglomeration and more uniform distribution were synthesized by the second route, and the particle size and oxygen content were 0.8 μm and 0.8 wt%, respectively. Moreover, the particle size similarity of TaB₂ powders by the two routes suggested that byproduct boron oxides, which were previously reported as the most important factor in promoting the coarsening of ZrB₂ powders by borothermal reduction, did not lead to the significant coarsening of TaB₂ powders.     

Hot Isostatic Pressing of Silicon Nitride with Boron Nitride, Boron Carbide, and Carbon Additions

Si₃ N₄ test bars containing additions of BN, B₄C, and C, were hot isostatically pressed in Ta cladding at 1900° and 2050°C to 98.9% to 99.5% theoretical density. Room-temperature strength data on specimens containing 2 wt% BN and 0.5 wt% C were comparable to data obtained for Si₃ N₄ sintered with Y₂O₃, Y₂O₃ and Al₂O₃, or ZrO₂. The 1370°C strengths were less than those obtained for additions of Y₂O₃ or ZrO₂ but greater than those obtained from a combination of Y₂O₃ and Al₂O₃. Scanning electron microscope fractography indicated that, as with other types of Si₃N₄, roomtemperature strength was controlled by processing flaws. The decrease in strength at 1370°C was typical of Si₃N₄ having an amorphous grainboundary phase. The primary advantage of non-oxide additions appears to be in facilitating specimen removal from the Ta cladding.     

High-Temperature Phase Relations in the System Y2O3-Ta2O5

The phase relations for the system y₂o₃–Ta₂o₅ in the composition range 50 to 100 mol% Y₂O₃ have been studied by solid-state reactions at 1350°, 1500°, or 17000C and by thermal analyses up to the melting temperatures. Weberite-type orthorhombic phases (W2 phase, space group C222₁), fluorite-type cubic phases (F phase, space group Fm3m )and another orthorhombic phase (O phase, space group Cmmm )are found in the system. The W2 phase forms in 75 mol% Y₂O₃ under 17000C and O phase in 70 mol% Y₂O₃ up to 1700°C These phases seem to melt incongruently. The F phase forms in about 80 mol% Y₂O₃ and melts congruently at 2454° 3°C. Two eutectic points seem to exist at about 2220°C 90 mol% Y²O₃, and at about 1990°C, 62 mol% Y₂O₃. A Phase diagram including the above three phases were not identified with each other.     

Optical Properties and Microstructure of Ta2O5 Thin Films Prepared by Ion Assisted Electron Beam Evaporation

An effective method for determining the refractive index of weak absorption transparent thin films was presented, which is also applicable to other weak absorption dielectric thin films.The as-deposited Ta2O5 thin films prepared by ion assisted electron beam evaporation showed a maxima transmittance as high as 93% which was close to that of the bare substrate, and exhibited a blue shift when the substrate temperature increased from room temperature to 250 ℃. The refractive index seemed to be immune to the substrate temperature and film thickness with its value about 2.14 at incidence wavelength of 550 nm. The surface morphology measured by atomic force microscopy (AFM) revealed that the microstructures lead to the slim optical difference, which was the interplay of substrate temperature and assisted ion beam.     

酸浸法从钨渣中回收铌、钽、钨

研究了钨渣的酸浸法优化处理工艺,在40℃条件下,分别用HCl和H2SO4处理50 g钨渣10m in:15%HCl溶液中Ta2O5、Nb2O5与WO3的回收率分别为86.1%、75.3%和73.9%,Ta、Nb、W分别富集了8~10倍;而在30%H2SO4中的回收率分别为95.2%、68.5%和79.8%,Ta、Nb、W仅富集了4倍左右。这是由于Ta、Nb盐类在HCl、H2SO4中的溶解度有差异,导致了Ta、Nb不同的回收率。     

Alumina supported tungsten hydrides, new efficient catalysts for alkane metathesis

Silica and alumina supported tantalum and tungsten hydrides were tested in alkane metathesis, for comparison of their catalytic properties. In propane metathesis [W]–H/Al₂O₃ proves to be twice more efficient than the usual [Ta]–H/SiO₂ catalyst which is still better than [Ta]–H/Al₂O₃ and [W]–H/SiO₂. Tungsten based catalysts lead to a narrower distribution in the products selectivity and to a higher amount of linear products than [Ta]–H/SiO₂. [W]–H/Al₂O₃ is also a better catalyst than [Ta]–H/SiO₂ for butane metathesis but is less efficient with ethane. Whereas the results in the case of propane or butane can involve the higher initial activity and a lower deactivation of the tungsten catalyst, in the case of ethane, mechanistic or kinetic aspects can be envisaged in particular concerning the difficulty to dehydrogenate ethane into ethylene.     

Microstructure and Microwave Dielectric Properties of Ba(Zn1/3Ta2/3)O3 Ceramics with ZrO2 Addition

The effect of ZrO₂ on crystallographic order, microstructure, and microwave dielectric properties of Ba(Zn_1/3Ta_2/3)O₃ (BZT) ceramics was investigated. A small amount of ZrO₂ disturbed the 1:2 cation ordering. The average grain size of the BZT significantly increased with the addition of ZrO₂, which was attributed to liquid-phase formation. The relative density increased with the addition of a small amount of ZrO₂, but it decreased when the ZrO₂ content was increased. Variation of the dielectric constant with ZrO₂ addition ranged between 27 and 30, and the temperature coefficient of resonant frequency increased abruptly as the ZrO₂ amount exceeded 2.0 mol%. The Q value of the BZT significantly improved with the addition of ZrO₂, which could be explained by the increased relative density and grain size. The maximum Q × f value achieved in this investigation was ∼164 000 GHz for the BZT with 2.0 mol% ZrO₂ sintered at 1550°C for 10 h.