共沉淀法制备铋黄颜料

采用共沉淀示由钒酸铋和钼酸铋制性能优良的无机铋黄颜料。试验发现,钒／钼配比是影响产品颜色的主要因素,随着Ｖ／Ｍｏ的减少,产品的绿色调加重,反之棕色调加重。采用正交研究了反应温度、ＰＨ值及反应时间对产品性能的影响,并确定了最佳反应条件。     

NPO型铋基焦绿石复相陶瓷的制备及介电性能

为获得温度稳定型高频高介材料,通过复相介电组成调控原理,将正温度系数型焦绿石相(Bi1.5Zn0.5)(Zr1.5Nb0.5)O7(BZZN)与负温度系数型(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7(BZN)混合构成BZN-BZZN复相材料.研究了该系列陶瓷的物相组成、晶体结构及介电性能随两相组成的变化规律.晶体结构精修获得了复相结构中两相的晶格常数、A-O'键长、B--O键长、O—B—O键角的变化.复相陶瓷的介电性能可通过两相比例有规律地调制,随着BZZN含量增多,(1-x)BZN-xBZZN介电常数εr略有下降,介电常数温度系数逐渐由负值向正值变化.当x=0.7时,获得高介电常数、零温度系数陶瓷材料:εr=123.2,tanδ=7×10-4,αε=5×10-6/℃.     

水热法制备钛酸铋钠无铅压电陶瓷粉体

以Bi(NO3)3·5H2O和纳米级Ti O2分别作为铋源和钛源,Na OH作为钠源和矿化剂,采用水热法制备钛酸铋钠无铅压电陶瓷粉体,(Na,Bi)Ti O3(NBT)粉体,并对样品进行了XRD和SEM表征。结果表明,水热反应温度为200℃时保温6 h,Na OH浓度为6 mol/L时,可制得结晶完全的立方相NBT,粉体呈球形,粒径约为1μm。水热反应温度、矿化剂浓度和反应时间的增加能促使晶化反应的进行和晶粒长大。     

含Sr铋基焦绿石材料的介电弛豫性能

采用传统固相反应烧结工艺制备(Bi1.5Zn0.5–xSrx)(Ti1.5Nb0.5)O7(BZTN,x=0.30,0.32,0.34,0.36,摩尔分数)铋基焦绿石陶瓷,研究该体系陶瓷的化学组成对物相结构、介电性能和弛豫特性的影响。X射线衍射分析表明:当Sr离子取代量较小时(x0.36),材料的相结构仍然保持立方焦绿石单相结构;当x=0.36时,出现微量SrTiO3杂相,但仍保持立方焦绿石主晶相结构。Sr离子的取代对介电性能产生显著影响:随着Sr离子取代量增加,样品的相对介电常数先增大后减小,介电损耗逐渐减小,并具有较大的正温度系数。观察到铋基焦绿石介电陶瓷的高温介电异常行为:系列样品在200～300℃,均出现明显的介电弛豫现象,并分析与讨论高温介电弛豫性能。     

共沉淀法制备钕掺杂钛酸铋粉体

以硝酸铋、钛酸丁酯和硝酸钕为原料采用共沉淀法制备掺钕钛酸铋粉体.用X射线衍射(XRD)和透射电镜(TEM)对所得粉体进行了表征.以甲基橙为目标降解物,借助紫外一可见分光光度计考察了样品的光催化性能.结果表明:钕掺杂对BT晶体的结构没有影响,但钕在BT中的溶解度有限.钕掺杂能提高BT的光催化性能,当钕掺杂量为0.35时B...     

化学共沉淀法制备纳米铋掺杂氧化锡

以SnCl4.5H2O和Bi(NO3)3.5H2O为原料,氨水为沉淀剂,采用化学共沉淀法制备了铋掺杂氧化锡(BTO)纳米粉体,考察了反应温度、滴定终点pH、铋掺杂量、煅烧温度和分散剂PEG-600对所得的纳米BTO粉体物相、晶粒度和形貌的影响,对粉末的前驱体进行综合热分析(TG-DTA),用X射线衍射(XRD)、扫描电镜(SEM)对产物的结构和形貌进行表征,得到共沉淀法制备纳米BTO粉体的最佳条件:反应温度60℃,滴定终点pH=3,煅烧温度600℃;该条件下制得BTO粉体的电阻率最小为3.48Ω.cm。     

水热法制备纳米陶瓷粉体技术

文章较为系统地概述了水热法制备纳米陶瓷粉体的技术方法、特点和研究进展。认为水热法是一种极有应用前景的纳米陶瓷粉体的制备方法.     

陶瓷粉体的制备技术

综述了精细陶瓷材料之主要原料———陶瓷粉体的各种制备方法。对最有发展前途的热化学气相反应法、激光诱导化学气相合成法、等离子气相合成法、沉淀法、水热法及溶胶—凝胶法的原理和工艺作了较为详细的介绍。     

化学共沉淀法制备纳米铋掺杂氧化锡的影响因素研究

以SnCl4.5H2O和Bi(NO3)3.5H2O为原料,氨水为沉淀剂,采用化学共沉淀法制备了铋掺杂氧化锡（BTO）纳米粉体,研究了反应温度、滴定终点pH值、铋掺杂量,煅烧温度和分散剂PEG-600对所得的纳米BTO粉体物相、晶粒度和形貌的影响,对粉末的前驱体进行综合热分析（TG-DTA）,用X-射线衍射（XRD）,扫描电镜(SEM)对产物的结构和形貌进行表征,得到共沉淀法制备纳米BTO粉体的最佳条件：反应温度60℃,滴定终点pH值为3,煅烧温度600℃;该条件下制得BTO粉体的电阻率最小为3.48Ω•cm。     

共沉淀法制备纳米镁铬尖晶石粉体

镁铬尖晶石具有较高的熔点而被广泛应用于耐火材料中。而常规镁铬尖晶石粉体因烧结温度较高，铬蒸发而使得耐火材料的致密度难以提高。为改善镁铬耐火材料的烧结性能，进行了纳米镁铬尖晶石粉体的研究：以Cr(NO3)3，Mg(NO3)2，PEG-400和CO(NH2)2为原料，采用共沉淀法获得了铬酸镁纳米粉(nc2o3：nMgo=1：1)的前驱体，经过超临界流体干燥(SCFD)制备出镁铬二元纳米气凝胶，经600℃煅烧后获得了纳米级立方相镁铬尖晶石粉体。经XRD，DSC-TG，BET和透射电镜分析，结果表明：前驱体纳米粉的比表面积为350～780m^2／g，平均粒径为1～2nm，煅烧后的纳米粉的比表面积为36～65m^2／g，平均粒径为5～10nm。     

Reaction moulding of metal and ceramic powders

A processing route for fabrication of products from hard metal and ceramic powders is described in which a reactive monomer such as ethylcyanoacrylate is used as carrier and binder with the opportunity of recovery through thermal depolymerization. A feasibility study has examined some of the main technical points including monomer–powder reactivity and rheology, debinding rates and compact green density. The stability of ethylcyanoacrylate with various powder volume fractions of silicon nitride and 316L stainless steel has been examined, with p-toluenesulphonic acid used as polymerization inhibitor, and it was found that mixes with higher powder volume fractions required higher levels of inhibitor. Assessment of the flow behaviour of several of the compositions showed them to be significantly non-Newtonian and the high viscosity of blends with a high loading of stainless steel suggests some premature polymerization. Measurement of green density of polymerized compacts demonstrated that high packing efficiency could be achieved. Thermogravimetry showed that rates of binder loss depended upon sample size and powder thermal conductivity.     

陶瓷粉化学镀钴工艺研究

根据化学镀原理,以镀后粉末的相对增重质量为主要指标,利用正交实验研究了在陶瓷粉末上进行化学镀钴。分析了钴离子浓度、酒石酸钠浓度、稳定剂浓度、温度以及pH对沉积效率的影响。测试了化学镀钴前后的微观形貌SEI图及XRD图。实验结果表明,溶液中的硫酸钴浓度、络合剂浓度、温度以及pH的增大,都会加快沉积速度。经X衍射分析表明,钴的晶体结构为体心六方结构。     

Growth behavior of nanosized ceria powders prepared by coprecipitation routes

Nanosized ceria (CeO₂) powders were obtained by coprecipitation routes of cerium nitrate hexahydrate [Ce(NO₃)₃·6H₂O]. The growth behavior of the nanosized CeO₂ powders was investigated by X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The XRD results showed that the dried precursor powders contained a single crystalline phase of CeO₂, and only a single phase of CeO₂ appeared when the dried precursor powders were calcined at different temperatures for various durations. Moreover, the crystallite size of CeO₂ increased on increasing the calcination temperature and duration. The kinetics equation of the nanosized CeO₂ powders grown between 673 and 1273 K for various durations is described as     

Effect of dispersant content and drying method on ZrO2@Al2O3 multiphase ceramic powders

ZrO₂@Al₂O₃ composite ceramic powders were prepared by solution combustion method with aluminum nitrate (Al (NO₃)₃) and 3?mol% yttria-stabilized tetragonal zirconia polycrystal (3Y- TZP) as the main raw materials, ammonium polyacrylate (PAA-NH₄) as a dispersant, urea (CO (NH₂)₂) as a reducing agent. The effects of PAA-NH₄ concentration and drying method on the microstructure and morphology of the ZrO₂@Al₂O₃ powders were investigated. The results showed that when the concentration of PAA-NH4 was 1.5?wt%, and the molar ratio of Al (NO₃)₃ to CO (NH₂)₂ was 1:2, the ZrO₂@Al₂O₃ powders with uniform grain size and high crystallinity could be synthesized by solution combustion drying method. Additionally, the abnormal growth of 3Y- TZP grain in ZrO₂@Al₂O₃ was suppressed and the crystalline phase transformation trend (t-ZrO₂ to m-ZrO₂) was obviously decreased after sintering at 1600?°C.     

气流循环粉碎法制备Al2O3超细粉的研究

以粗颗粒Al2O3粉为原料,采用气流循环粉碎法制备了d50＜1μm的Al2O3超细粉.按正交表L9(34)安排正交试验,通过方差分析确定了制备Al2O3超细粉的最佳气流循环粉碎条件,并分析了各因素对气流循环粉碎过程的影响程度.不同物料的最佳气流循环粉碎条件应通过实验确定.在本研究的实验条件下,制备Al2O3超细粉的最佳条件为进气压力1.0 MPa,给料压力0.4 MPa,循环时间1.5 h.     

银包覆铜微粉的制备与性能研究

以硫酸铜为原料,采用葡萄糖预还原法在乙二醇介质中制备微米级铜粉,由直接置换法制备铜包银型微粉;通过导电性实验、粒径及粒径分布分析等,优化了制备银包覆铜微粉的工艺条件。     

水热法制备氧化锆微粉的进展

二氧化锆纳米粉是制造高科技陶瓷的重要原料，水热法是目前生产纳米粉体最具发展潜力的工艺方法之一。综述了水热法（包括水热沉淀、水热氧化、水热电埋弧、微波水热等）在生产纳米二氧化锆系粉体中的应用，以及水热法的发展情况。     

Compression behavior of ceramic powders by inductive plasma sphero process

Strength of ceramic powders can be affected by the powders’ structure. In this study, two typical structured yttria-stabilized zirconia (YSZ) powders, agglomerated and sintered, were tested in a micro compression machine. The results showed that the sintered powders exhibited much higher compressive strength than the agglomerated powders. It was also found that the strength of the agglomerated powders was independent on the particle size due to their uniform microstructure, while the sintered powders showed decreased strength with the increasing of particle size because they had lower level of sintering. Finite element analysis was performed which indicated that thinner shells trended to sustain higher tensile stress/strain than the thicker shells, so the larger particles with thinner shells were easier to break.     

纳米三氧化二铋粉体的制备研究

以三氯化铋为原料,采用二步转化法,直接制得纳米三氧化二铋.研究了溶液浓度、反应温度、体系pH,以及表面活性剂对产物纯度和粒度的影响.实验得出该法制备纳米三氧化二铋的最佳工艺条件为三氯化铋浓度为0.3 mol/L,水解温度为室温,pH控制在0.8,转化用碱浓度为5 mol/L,转化温度为90 ℃,pH为12,分散剂用量为4×10-3 mol/L.分析结果表明制得的三氧化二铋为球状β-三氧化二铋,分散性好,平均粒径约90 nm,产品纯度达到99.8%,产率达到97.5%.