用反萃界面沉淀法制备二氧化钛超细粉体

用反萃界面沉淀法,以氨水为反萃剂,通过优化煅烧温度和反萃条件制备出超细TiO2光催化剂.结果表明,采用反萃沉淀法制备超细TiO2光催化剂,改变煅烧温度和水油相加入的方式、降低氨水的浓度、制备温度和陈化时间等因素均有显著的影响.用氨水反萃制备纳米TiO2其最佳煅烧温度为350℃,氨水的浓度和陈化温度存在最佳值.氨水浓度(体积比)为1:5,陈化温度为17.5℃有利于生成小颗粒;陈化时间较短和将水相加入油相有利于生成小颗粒.     

砂磨粉碎制备SiC超细粉体

砂磨粉碎是制备超细陶瓷粉体的有效途径之一,避免了传统球磨、酸洗工艺对环境的污染。本文采用砂磨粉碎工艺制备ＳｉＣ超细粉体,研究了砂磨粉碎制备过程中料浆固含量、球料比和砂６磨时间等工艺条件对粉体尺寸和尺寸分布的影响,在一定工艺条件下,将中位粒径为７．３ｕｍ的高纯ＳｉＣ粗粉砂磨粉碎１８ｈｒ,得到了中位粒径为０．４７ｕｍ、粉体尺寸分布范围窄、氧含量小于１．５ｗｔ％的超细ＳｉＣ粉体。     

超细粉体的制备与表征

概要地介绍了超细粉体的表征方法以及超细粉体的机械制备等手段     

用超临界溶液快速膨胀法制备超细粉体

利用超临界溶液快速膨胀法制备超细粉体 ,是近年来提出并受到研究者重视的一种很有应用前景的新的粉体制备技术。本文介绍了该技术的基本原理、理论研究和应用研究的现状及主要成果     

砂磨粉碎制备SiC超细粉体

砂磨粉碎是制备超细陶瓷粉体的有效途径之一 ,避免了传统球磨、酸洗工艺对环境的污染。本文采用砂磨粉碎工艺制备 Si C超细粉体 ,研究了砂磨粉碎制备过程中料浆固含量、球料比和砂磨时间等工艺条件对粉体尺寸和尺寸分布的影响 ,在一定工艺条件下 ,将中位粒径为 7.3μm的高纯 Si C粗粉砂磨粉碎 1 8hr,得到了中位粒径为 0 .4 7μm、粉体尺寸分布范围窄、氧含量小于1 .5wt%的超细 Si C粉体。     

二氧化锡超细粉体制备方法综述

本文综述了采用溶胶-凝胶法、水热法、化学沉淀法、硝酸氧化法、气化法等制备超细SnO2的研究进展,阐述了不同方法制备超细SnO2粉体的过程、条件及原理,并分析了这些制备超细SnO2方法的特点及存在的不足,开拓了其未来的发展前景.最后,指出了重点研究方向应是改善SnO2的制备工艺及进一步提高其纯度.     

液氨沉淀法制备ZnO超微粉

以Zn(NO3 ) 2 为原料 ,NH3 ·H2 O为沉淀剂 ,采用直接沉淀法制备Zn(OH) 2 白色沉淀 ,经洗涤、干燥、煅烧后生成ZnO超微粉末。通过TEM观察到ZnO为球形晶体 ,平均粒径 15 0nm。探讨了溶液pH值、沉淀剂浓度、反应时间、反应温度对前躯体Zn(OH) 2 粒度的影响以及煅烧过程中煅烧温度与煅烧时间对ZnO粒度的影响 ,得出了最佳工艺条件。     

超临界二氧化碳制备超细粉体的工艺研究进展

【目的】为了解决使用传统工艺制备超细粉体时存在的粒径分布宽、颗粒均匀性差、溶剂残留多、操作条件苛刻等问题,寻求更为优异的超细粉体制备工艺。【研究现状】综述超临界CO₂制备超细粉体在医疗、材料和化学等领域的应用;总结超临界CO₂作为溶剂、抗溶剂和辅助介质时的代表超临界溶液快速膨胀法(rapid expansion of supercritical solutions, RESS)、气体抗溶剂法(gas anti-solvent, GAS)、超临界抗溶剂法(supercritical anti-solvent, SAS)、气体饱和溶液法(particles from gas-saturated solutions, PGSS)、带鼓泡干燥器的CO₂辅助雾化法(carbon dioxide assisted nebulization with bubble dryer, CAN-BD)、超临界流体辅助雾化法(supercritical assisted atomization, SAA)、强化混合超临界流体辅助雾化法(supe...     

等离子体法制备超细粉体氮化铝的研究

以微米级铝粉为原料 ,用N2 热等离子体法制备了超细氮化铝粉体。在等离子体功率12kW ,运行N2 流量 2m3/h ,急冷NH3流量 0 6m3/h ,送粉N2 流量 0 8m3/h条件下 ,铝粉全部转化为纳米氮化铝。采用SEM技术和粒度分析仪对产品进行了分析 ,制得的氮化铝粉末平均粒径为10 0nm ,粒度分布为 4 0～ 14 0nm     

直接沉淀法合成超细氧化锌的研究

以氯化锌为原料 ,草酸铵为沉淀剂 ,采用直接沉淀法制备超细氧化锌 ,对氧化锌的前驱体 -草酸锌的合成以及焙烧工艺进行了详细研究。试验讨论了反应温度、反应物浓度、溶液 pH值和沉淀反应时间等因素对草酸锌粒度的影响 ,以及焙烧过程中被烧温度与被烧时间对氧化锌粒度的影响 ,结果发现 ,在严格控制上述工艺参数的条件下 ,可以获得粒度 <70nm的氧化锌产品。     

Structural properties of ultra-fine zirconia powders obtained by precipitation methods

We have investigated various aspects of the stabilization of the tetragonal (t) and cubic (c) forms (metastable at room temperature) with respect to the monoclinic (m) form in ultrafine zirconia powders obtained by calcining amorphous hydrated zirconium oxides at various temperatures. They were prepared by precipitation from ZrOCl₂ at different pH, using either NaOH or NH₄OH solutions. We have clarified the importance of the role of Na⁺ ions in the initial zirconia gel as stabilizers of the cubic form. On the contrary, almost pure tetragonal phase was obtained at moderately low temperatures starting from precursors with a low content of sodium (0.5wt%). By means of an X-ray diffraction (XRD) study and a suitable peak profile fitting procedure (convolutive method for the pattern decomposition followed by a straight-forward Fourier analysis) the amounts of the different crystallographic forms as well their microstructural properties such as crystallite size and lattice disorder (when present) were obtained. The thermal evolution of the systems were followed by both differential thermal analysis (DTA) and XRD, and we studied the martensitic t m transformation obtained by pressing a zirconia powder containing a prevailing content of t form at room temperature. To obtain further microstructural and morphological information on the c m transition, transmission electron microscopy and small angle X-ray scattering techniques were used.     

均匀沉淀法制备碳纳米管/氧化锌复合材料的研究

采用均匀沉淀法制备了碳纳米管(CNTs)负栽氧化锌(ZnO)粒子复合材料,并利用扫描电子显微镜(SEM)、X光衍射分析(XRD)以及热失重分析(TGA)手段对复合粒子进行了表征.研究结果表明:锌离子浓度取0.4mol/L至1.0mol/L时,所得复合材料中的氧化锌粒子大小均匀细小,分散性较好,形貌以粒状为主,大小在40nm左右;纳米氧化锌粒子与碳纳米管结合力较强,CNTs/ZnO复合材料在超声作用下能够稳定存在;反应时间越长,氧化锌粒子含量越高,晶粒越大;热解温度越高,热解时间越长,氧化锌晶粒尺寸越大.     

Preparation of nano-sized flower-like ZnO bunches by a direct precipitation method

In this work, nano-sized ZnO particles were prepared by a direct precipitation method with Zn(NO₃)₂·6H₂O and NH₃·H₂O as raw materials, and the impact of the synthesis process was studied. The optimal thermal calcined temperature of precursor precipitates of ZnO was obtained from the differential thermal analysis (DTA) and the thermal gravimetric analysis (TGA) curves. The purity, microstructure, morphology of the calcined ZnO powders were studied by X-ray diffraction (XRD), energy dispersive X-ray spectrum (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesized ZnO powders had a wurtzite structure with high purity. The final products were of flower-like shape and the nanorods which consisted of the flower-like ZnO bunches were 20–100 nm in diameter and 0.5–1 μm in length. The effect of process conditions on the morphology of ZnO was discussed.     

电化学研磨法制备超细镍粉

以锂离子电池为微反应器,电化学还原NiO制备了超细镍粉。X射线衍射结果表明所得粉末为纯相Ni,晶粒尺寸约5nm。激光粒度分布测试结果表明Ni粒度分布较窄,中位径集中在200～600nm。透射电镜照片显示颗粒粒径在80～200nm之间;放电电流密度的增加和放电温度的提高都使产物粒径有变大的趋势;在分散过程中加入不同的表面活性剂,可以提高产物Ni的分散性能。     

非均匀沉淀法制备Cu包覆ZrW2O8复合粉体的研究

通过分部固相法制备ZrW2O8粉体。以ZrW2O8、CuSO4·5H2O（分析纯）和无水Na2CO3（分析纯）为原料，采用非均匀沉淀法制备了Cu包覆ZrW2O8复合粉体，并利用XRD、SEM、EDS测试手段，分析包覆粉的物相和形貌，研究了反应液浓度、表面活性剂、反应液滴加速度等反应条件对包覆效果的影响。研究表明：通过非均匀沉淀法可以制备Cu包覆ZrW2O8复合粉体，其关键是控制反应液的浓度和滴加速度，同时，不同分子量的表面活性剂对包覆前驱体的分散性影响很大．     

Preparation of Fe2O3/Al composite powders by homogeneous precipitation method

The Fe₂O₃/Al composite powders were prepared by homogeneous precipitation method. The influence of the concentration of Fe²⁺ and the molar ratio of raw materials on the preparation of Fe₂O₃/Al composite powders were investigated. X-ray diffractometer, scanning electron microscope, Fourier transform infrared spectroscopy and differential thermal analysis were used to analyze the morphology and structure of the Fe₂O₃/Al composite powders. The results show that the content of iron oxide in the composite powders could be effectively controlled by adjusting the concentration of Fe²⁺ and the molar ratio of raw materials in the plating solution. The surface of Al particle was coated with a layer of thick and dense iron oxide. The core-shell Fe₂O₃/Al composite powders with Fe₂O₃ content of 14.1% were produced, the coating efficiency of Fe₂O₃ reaches more than 77%. The iron oxide, which coated on the surface of the aluminium particle is flower-like cluster structure, each flower-like cluster is constituted by nano-flaky iron oxide.     

超细Mo-30Cu复合粉末的烧结行为

采用溶胶-喷雾干燥-煅烧-氧还原方法制备了晶粒尺寸为17-30 nm的超细Mo-30Cu复合粉末,在制备过程中经历了一系列的相转变,由喷雾干燥复合盐前驱体Cu7.6O8(NO3)+(NH4)2(Mo4O13)+(NH4)6(Mo7O24)(H2O)4+Cu4Mo5O17+CuMoO4在450℃煅烧后转变为CuMoO4+MoO3复合氧化物,在300℃低温还原转变为MoO2+Cu2O+Cu三相,再在700℃高温还原完全转变为Mo+Cu两相复合粉末.该粉末在1050-1200℃烧结时从亚稳态Mo(Cu)固溶体逐渐转变为Mo和Cu相,在1050℃烧结后得到致密度为99.7%的细晶合金.合金的最大抗拉强度可达755 MPa,最大延伸率可达15.8%.