共查询到19条相似文献,搜索用时 140 毫秒
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以硝酸钇为原料溶液,采用氨水-草酸2步沉淀法合成了中心粒径(D50)为1.00~2.00 μm的氧化钇粉体,粉体分散性好,粒度可控.考察了沉淀剂的浓度、物料的浓度、反应温度、加料速度以及pH值等因素对氧化钇粉末中心粒度的影响.采用激光粒度仪、比表面仪、扫描电子显微镜等仪器对实验过程及实验结果进行表征和分析.结果表明,在氨水浓度为1.0 mol/L、草酸质量浓度为10 %、滴加速度为20 mL/min、草酸溶液温度为80 ℃、氨水沉淀后pH值在7~8之间、草酸转化后pH值小于1的条件下,可通过调节硝酸钇的浓度在0.4~0.8 mol/L之间,以制备中心粒径(D50)在1.00~2.00 μm范围内、比表面积在3.2~13.3 m2/g之间的氧化钇粉体. 相似文献
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以纯氧氯化锆、氧化钇和硝酸为原料,以碳酸铵沉淀剂,采用共沉淀法制备碳酸锆与碳酸钇的混合物,经喷雾干燥制粒、热处理后得到纳米YPSZ团聚粉末.由等离子喷涂方法制备了YPSZ涂层,用XRD、SEM等分析手段观察和确定涂层的物相组成和显微结构. 相似文献
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采用碳酸钠或碳酸氢钠作为沉淀剂,在室温(5~35℃)下沉淀氯化钇料液,随后经煅烧制备出氧化钇粉体。采用激光粒度仪、扫描电镜和霍尔流速计(漏斗法)表征粉体,研究了沉淀剂种类、沉淀剂/氯化钇摩尔比及聚合物分散剂(PVA)对形成的氧化钇粉体的表面形貌、粒度分布、松装密度的影响,确定了最佳的工艺条件:以碳酸钠作为沉淀剂,Na2CO3/YCl3摩尔比≤1.5,聚合物分散剂(PVA)的质量分数为0.001%~0.01%。在上述条件下获得的氧化钇粉末的粒度大且分布较窄,D50为20~100μm,(D90-D10)/(2D50)<0.5,松装密度为1.0~1.2 g/cm3,球形度良好,具有较好的分散性和流动性。本工艺简单易控,易于工业化生产,成本低,无污染。 相似文献
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《稀有金属》2020,(1)
以废旧硬质合金和可溶性钇盐为原料,采用固-液掺杂,通过球磨将钇源引入钨钴氧化物粉末中,再经过两步还原制备纳米WC-Co复合粉。采用扫描电子显微(SEM)、能谱仪(EDS)与X射线衍射(XRD)分别表征各阶段所获得的粉体的微观形貌、物相组成,分析了氧化钇对紫钨长径比的影响及其作用机制,同时分析了氧化钇对合成纳米WC-Co粉体粒度的影响规律。试验表明,氧化钇的掺杂影响了WO_(2.72)特定晶面的能量,促进WO_(2.72)沿(010)晶面择优生长;试样掺杂氧化钇后,其反应活性变大,使(010)晶面的形核驱动力要大于其他晶面。因此,制备的WO_(2.72)棒更加细长。与未掺杂氧化钇的试样相比,其棒的直径由200 nm减小到140 nm,长度增加了约1倍。此外,在碳化反应过程中,均匀分散的氧化钇增大了WC的非均匀形核率,并阻碍了WC-Co粉体颗粒扩散迁移,从而阻止其合并长大,使得最终合成的WC-Co复合粉具有均匀的粒度分布,平均粒径约为90nm。 相似文献
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氧化钇纳米粉末的制备 总被引:10,自引:0,他引:10
使用草酸作沉淀剂,采用液相沉淀法成功制备了氧化钇纳米级粉末。对该粉末的扫描电镜图以及差热分析图等进行了分析以及对溶液的pH值、浓度、反应方式、分散剂及煅烧温度等因素进行了考察,得出了较为理想的工艺条件。在此工艺条件下制得的氧化钇粉末粒径为20~50m。 相似文献
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Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdFeB waste with oxalic acid was developed.The high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic benefit.Results of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,respectively.Rare earth oxalate and Fe(C2O4)33- were left in the residue and the leaching solution,respectively.The leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical reaction.The leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt electrolysis.For the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC2O4-2H2O). 相似文献
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AbstractA new approach to produce ultrafine WC/Co powder by a mechanochemical process was made to improve the mechanical properties of advanced hardmetals and to cut production costs. For powder preparation, the water soluble salts containing W and Co components were used as starting materials. After synthesis of the precursor powder from an aqueous solution by a spray drying technique, a salt removing heat treatment in air atmosphere was carried out to prepare the oxide powder. The oxide powder was mixed with carbon black by ball milling and this mixture was converted at 800oC to the nanophase WC/Co powder in H2 and N2 atmospheres. The average size of the WC particle was 100-150 nm. The possibility of achieving high density sintered material with an ultrafine and homogeneous microstructure using grain growth inhibitors, such as tantalum and vanadium carbides, has been shown. 相似文献
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溶胶-凝胶法制备钇铝石榴石纤维 总被引:3,自引:3,他引:0
以氯化铝、金属铝粉、氧化钇、冰醋酸为原料,采用溶胶—凝胶法制备了钇铝石榴石纤维。研究氯化铝和金属铝粉比例以及醋酸的加入,对前驱体溶胶纺丝性能的影响。结果表明,加入醋酸可得到纺丝性能良好的前驱胶体溶胶。凝胶纤维在1 000℃煅烧2 h,全部结晶为钇铝石榴石,纤维直径10~40μm。 相似文献
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以钴粉和草酸(H2C2O4)为原料,采用固液界面反应法制备针状草酸钴(Co2C2O4·2H2O)粉体.用扫描电镜(SEM)、X射线衍射仪(XRD)和激光粒度仪对粉体进行表征,研究反应温度、钴粉浓度、草酸与钴粉的计量比以及无机酸的种类和用量对草酸钴粉体的形貌和长径比的影响.结果表明,反应温度为30℃时草酸钴粉体多为颗粒状... 相似文献