共查询到20条相似文献,搜索用时 31 毫秒
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纳米级WO3粉的还原动力学特征 总被引:11,自引:4,他引:7
在一定的温度和氢气流量条件下,用热分析天平精确测量WO3还原反应过程中,不同时间的质量变化,并用X射线衍射分析(XRD)进行物相鉴定,绘制绘米级WO3(粒径≤50nm)的还原动力学曲线,分别讨论了由WO3制备WO2.90及由WO2.90制备W粉两阶段的还原动力学特性,试验结果表明;纳米级WO3粉可在4900℃,37min完全被还原为WO2.90(蓝钨),而WO2.90则在750℃,45min完全被还原为W粉,TEM观测表明,W粉粒度小于80nm. 相似文献
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WC粉中聚集体成因分析 总被引:3,自引:0,他引:3
谢康德 《稀有金属与硬质合金》2000,(3):5-10
对WC粉中聚集体的成因进行了试验研究。结果表明:保证原料氧化钨相成分单一和性能稳定是生产粒度均匀、聚团少的优质WC粉的前提;若普通蓝钨中平杂其他相,尤其是WO2.72相,则生产的W粉、WC粉中容易产生聚集体;WC中Fe含量的增加会使WC粉聚集程度明显增加,而且,同一种原料,不同工艺生产的W粉、WC粉的聚集体也不同,用普通蓝钨常规氢还原生产细W粉时,聚团现象无法避免。但在后续工序能基本得到打散,若碳 相似文献
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Chung-Hsin Lu Chung-Tao Chen Baibaswata Bhattacharjee 《中国稀土学报(英文版)》2006,24(6):706-711
The synthesis of BaMgAl10O17: Eu^2+ (BAM) phosphors using the sol-gel method and their luminescence properties were reported. The blue-light emitting BAM was synthesized using citric acid and ethylene glycol as chelating materials. Emission of blue-light was obtained from these phosphors. The luminescent intensity increases as the temperature of heat treatment is increased, This study investigated the effects of the molar ratio of ethylene glycol to citric acid (Ф value), with respect to the phase formation and luminescence properties of BAM. The variation of the Фvalue resulted in the change of the sol-gel reaction mechanism and the microstructures of the resultant powders. An increase in Фvalue leads to an increase in the rate of BAM phase formation. The photoluminescent intensity of the prepared phosphors increases with heating temperatures because of enhanced crystallization. 相似文献
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硬质合金中WC晶粒内部微孔形成原因探讨 总被引:1,自引:0,他引:1
利用扫描电镜对以蓝钨与黄钨为原料制得的粗颗粒W粉、WC粉进行形貌观察,并与其对应的WC-Co硬质合金金相组织进行了对比。以此为基础对硬质合金中WC晶粒内部微孔这一比较常见的现象作出解释,即合金中WC晶粒内部微孔主要来源于原料W粉。实验结果表明,选用蓝钨为硬质合金生产原料可使合金中WC晶粒内部微孔明显减少,从而使合金的综合性能得到提高。 相似文献
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概述了Eu2+激活的钡镁多铝酸盐(BaMgAl10O17:Eu2+, BAM)蓝色荧光粉在等离子显示领域中的研究现状; 简要介绍了BAM的晶体结构, 目前几种BAM的合成方法, 并展望了PDP用蓝色荧光粉的研究方向。 相似文献
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分析了综合应用振动分析技术、热成像分析技术有效判断轴承故障部位和劣化趋势,以及应用光谱分析技术分析轴承材料化学元素含量对轴承故障的影响,并做好上机前轴承的光谱检测,有效降低了轴承故障,做好轴承的预知维修. 相似文献
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高硫尾矿配制成的膏体表现出不同程度的强度劣化,高硫膏体强度劣化能引起充填体质量的巨大变化.通过不同硫含量的膏体强度劣化实验,同时结合X射线衍射物相分析和环境扫描电镜分析,对高硫膏体的劣化规律和劣化机理进行了分析.得出含硫尾矿在一定程度上能促进膏体早期强度增长,却抑制了后期强度发育,硫含量越高,膏体后期强度劣化越显著.硫化物氧化生成的硫酸盐能促进膨胀性钙矾石和石膏类物质的生成.同时酸性环境造成了C-S-H的脱钙和CH的分解,已形成的胶凝体系遭到破坏,进一步促进了充填体的劣化.通过孔隙计算模型对晶体膨胀应变和裂纹发育过程进行了分析,阐述了膨胀性物质的线弹性应变发育机理. 相似文献
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Ca-doped Ba Mg Al10O17:Eu2+,Mn2+(BAM) blue phosphors were synthesized by flux assisted solid-state reaction method using Ca F2 and Ba F2 as co-flux.Good dispersity and particle size homogenization of hexagonal pure phase BAM were obtained by sintering at 1400 ℃.The effects of the Ca2+ ions content on the structure, morphology and photoluminescence properties of the phosphors were studied.The results indicated that the incorporation of Ca could decrease the lattice constant, improve the homogeneity and dispersity and enhance the photoluminescence(PL) intensity of the phosphor effectively.The optimum Ba0.86Ca0.04Mg0.97Al10O17:0.1Eu2+,0.03Mn2+ PL intensity was enhanced for about 30% and relative brightness was improved about 4%.Furthermore, the synthesized BAM and commercial BAM phosphors were annealed for 30 min at 600 oC in air.The Ca-doped phosphors had stronger emission intensity, higher brightness and better chromaticity stability than that of the commercial phosphor.These results indicated that Ca-doped blue phosphors had good potential applications in the commercial tricolor fluorescent lamps as well as in other display and lamps. 相似文献