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1.
同质溶胶包覆BaTiO_3纳米粉体的烧结性能   总被引:2,自引:1,他引:1  
采用溶胶–凝胶法制备了BaTiO3溶胶,并在BaTiO3纳米粉体表面原位包覆一层均匀的同质溶胶。表征了包覆的BaTiO3纳米粉体的性能,研究了包覆量和烧结温度对包覆样品相对密度的影响。结果表明:在BaTiO3纳米粉体表面原位包覆了一层5~6nm厚的同质均匀溶胶。包覆量为BaTiO3粉体质量的3.0%时包覆效果最佳;1260℃烧结的包覆粉体样品,较未包裹的BaTiO3粉体具有更高的相对密度,前者为96.48%,而后者仅为75.40%。包覆粉烧结体断面致密,而原始粉烧结体断面则有明显气孔。  相似文献   

2.
CaO-ZrO2纳米粉体的制备和表征   总被引:5,自引:0,他引:5  
采用醇-水法和柠檬酸络合法制备了CaO-ZrO2粉体,用XRD和TEM等手段对粉体的结构和形貌进行了表征,结果表明:醇-水法所得粉体的粒径在70nm左右,基本无团聚体存在;至800℃时,晶粒已经发育完好,与固相法相比,其合成温度降低了600℃左右,晶型结构为四方晶型,无单斜相存在,而柠檬酸络合法所得粉体中含有大量单斜相,将醇-水法所得粉体加入到BaTiO3中,进行烧结实验,与固相法合成的CaO-ZrO2粉体相比,它使BaTiO3的烧结温度降低了20℃左右。  相似文献   

3.
以钛酸四丁酯与醋酸钡为钛酸钡前驱体,PEG为分散剂,硝酸钐为掺杂物种给体,采用溶胶-凝胶法制备改性的Sm掺杂BaTiO3纳米粉体。样品经X射线衍射(XRD)与差热-热重联用(DSC-TGA)的方法对其进行了表征。研究了煅烧温度与分散剂对BaTiO3粉体粒径与相的影响。结果表明:立方相在700~850℃生成,前驱体经950℃热处理制得后呈四方相BaTiO3。分散剂PEG可抑制BaTiO3晶粒增长;随煅烧温度升高,粉体粒径增大。适量Sm掺杂可以抑制杂质BaCO3相的形成。  相似文献   

4.
粉体粒度对BaTiO_3陶瓷结构与电性能的影响   总被引:2,自引:0,他引:2  
以采用共沉淀法制备的钛酸钡(BaTiO3)粉体为原料制备陶瓷。并利用XRD、DSC、SEM等分析手段对陶瓷材料的物相、相转变、显微结构进行表征,和利用电容测量仪、粒度分析仪等对陶瓷材料的电性能及粉体的粒度进行测试。研究了粒度对BaTiO3陶瓷微观结构和介电性能的影响。结果表明:随着预烧温度的提高,粉体的粒度增大,其陶瓷烧成温度也相应提高,并获得了优良的介温性能,粉体粒径为360nm的BaTiO3粉体经1290℃烧结后居里峰介电常数达到8119。  相似文献   

5.
本实验用溶胶-凝胶法制备了平均颗粒尺寸30nm左右的Yb2O3-ZrO2超细粉,获得了粉体颗粒小、分布均匀,颗粒形貌较理想,无硬团聚的超细粉,并探讨了高分子表面活性剂对粉末性能的影响。  相似文献   

6.
双重熔盐法制备片状BaTiO_3粉体   总被引:1,自引:1,他引:0  
用双重熔盐法制备片状Bi4Ti3O12粉体,以Bi4Ti3O12为中间产物通过离子交换制备了BaTi03片状粉体,并对其工艺过程进行了优化.利用X射线衍射分析合成粉体的相结构,用扫描电子显微镜观察其显微形貌.初步探讨了BaTiO3片状粉体的生长机理.结果表明:反应温度和化学组成对中间产物Bi4Ti3O12的微观形貌具有显著影响,在1 000℃以下时,随着反应温度升高,片状尺寸增大;当相对增加Bi2O3的量时,Bi4Ti3O12片状的尺寸增大.通过离子交换制备BaTiO3时,除了模板Bi4Ti3O12的形貌对BaTiO3的晶粒生长具有影响外,反应温度和化学组成同样对BaTiO3的晶粒生长具有显著影响.合成片状Bi4Ti3O12粉体的最佳的条件为:BaTiO3与Bi4Ti3O12的摩尔比为10:1,1 000℃合成2h.  相似文献   

7.
柠檬酸盐溶胶-凝胶法低温合成纳米BaTiO3粉体   总被引:3,自引:0,他引:3  
利用XRD,DTA,TGA,SEM,TEM等分析手段研究了柠檬酸盐溶胶一凝胶法低温合成Y2O3掺杂的BaTiO3粉体的方法,研究了溶液pH值、水含量、煅烧温度等因素对粉体的影响。结果表明,该方法能在600℃下2h合成单相的四方BaTiO3粉体,粉体的一次颗粒粒径达30nm。  相似文献   

8.
BaTiO3粉体的水热法合成   总被引:11,自引:0,他引:11  
本文阐述了水热合成粉体的一般原理及其与其它方法相比的特点。讨论了水热合成BaTiO3粉体的基本机理(包括原位转变机理和溶解-沉淀机理)、影响因素和存在的一些问题。  相似文献   

9.
BaTiO3铁电微晶立方-四方相变热力学分析   总被引:5,自引:2,他引:3  
张栋杰  姚熹 《硅酸盐学报》2003,31(5):441-444
利用溶胶—凝胶方法制备了BaTiO3凝胶,然后经过不同的退火处理,制备了BaTiO3微品陶瓷。XRD证实了1100℃,BaTiO3微晶存在明显的四方相。利用热力学分析的差减微分方程和非等温Johnson—Mehl—Avrami(JMA)方程对BaTiO3微晶的四方—立方相交的动态过程进行了分析,并对其相交过程用修正的JMA方程进行了具体描述;其相交活化能为170~190kJ/mol;相交指数为1,说明BaTiO3微晶的四方—立方相交是一级相交。  相似文献   

10.
纳米复合Fe-SiO2粉体的制备和结构   总被引:2,自引:0,他引:2  
采用非醇盐溶胶-凝胶工艺可获得Fe与Si摩尔比达4.5/1的均匀凝胶,发现可以通过控制SiO2的含量和热处理条件来控制相结构和晶粒尺寸,热处理过程中α-Fe相是由Fe3O4相还原而来,材料中有大量氧参与反应是工艺中采用了沉淀胶步骤的结果,最终制备了纳米复合Fe-SiO2粉体。  相似文献   

11.
Advantages of chemically prepared powders for electronic ceramics have been demonstrated for a number of multilayer capacitor (MLC) dielectrics. A cost-efficient precipitation process was developed to produce undoped or doped crystalline barium titanate powder with a narrow particle size distribution close to 0.5 μm. More complex compositions, e.g., barium-neodymium titanate, were amorphous as precipitated but could be crystallized by calcination below 1000°C. Additional compositional modifications, to adjust electrical properties or to lower sintering temperature, were accomplished by doping the surface of the powder particles using a solution coating process. Exceptional fired densities and electrical performance were obtained.  相似文献   

12.
钡钛醋酸盐凝胶制备BaTiO3粉体   总被引:3,自引:1,他引:2  
本文报道了用sol-gel法制备钡醋酸盐凝胶,并分别作高灼烧和水热处理制备BaTiO3粉体。通过对产物的表征,比较了这两种处理过程,进而对水热条件下陶瓷粉体的形成机理作了探讨。由于水热条件,凝胶在反应介质中溶解,进而结晶形成晶粒,因此所形成的BaTiO3晶粒线度小;线度分布范围窄。晶粒形貌完整,明显优于高温灼烧处理后得到的粉体。  相似文献   

13.
铌酸锶钡/钛酸锶钡复相陶瓷制备新工艺研究   总被引:1,自引:0,他引:1  
本文以钛酸四丁酯等配制溶胶前驱体溶液,通过控制前驱体溶液中各组分的配比成功制备了粘稠的溶胶溶液,以悬浮传统固相烧结工艺制备的微米级铌酸锶钡陶瓷粉体,在超声分散等的作用下形成均匀凝胶,最后成功制备出复相陶瓷坯体。采用X射线及扫描电镜对其进行表征,同时对其制备工艺及烧结制度进行了分析。结果表明:此工艺具有工艺简单,成本低,两相固溶均匀,且在一定程度上能够抑制在烧结过程中晶粒异常长大等优点,为科研工作者提供了一条新的工艺路线。  相似文献   

14.
采用不同偶联剂表面处理环己烷-负离子粉末溶胶,通过离心沉降的方法研究了表面处理对负离子粉末表面性质的影响,并考察了聚丙烯/负离子粉末共混物的纺丝性能。结果表明,选择单烷氧型钛酸酯类偶联剂质量分数8%时,经过处理后负离子粉末与聚合物基体界面结合状况得到改善,微粒的分散性较好,表面处理效果最好。纺丝时组件压力上升情况得到明显改善,且纺丝状况比较稳定。  相似文献   

15.
采用钛酸酯对纳米贝壳粉(SP)进行了表面改性,并制备了改性纳米贝壳粉;通过与天然胶乳共混,制备了天然橡胶/贝壳粉(NR/SP)纳米复合材料;使用傅里叶红外光谱仪、扫描电子显微镜、表面接触角测定仪、XRD衍射分析仪、激光粒度仪和电子拉力试验机等研究了改性纳米贝壳粉对天然橡胶纳米复合材料力学性能的影响。结果表明,改性剂钛酸酯成功地偶联到贝壳粉表面,经过表面化学改性后贝壳粉表面接触角由73.5°增大到110.8°;当纳米贝壳粉用量为10%时,NR/SP复合材料可获得最佳力学性能,拉伸强度可达到34.05MPa。  相似文献   

16.
Micrometer‐sized structures consisting of TiO2 nanoparticles were prepared using the sol–gel technique in combination with the structure‐directing agent triethanolamine (TEA). The interaction of the TEA with the hydrolyzed sol–gel products led to the formation of TEA titanate complexes, which then enabled the assembly of sol–gel‐precipitated nanosized powders. A subsequent thermal treatment of these powders resulted in the formation of micrometer‐sized structures consisting of TiO2 anatase and rutile nanoparticles. To characterize the prepared powders, FTIR spectroscopy, XRD analysis, the Brunauer‐Emmett‐Teller method (sBET), UV–Vis spectrometry and electron microscopy (FE‐SEM, and TEM) were employed. The photocatalytic degradation of the azo dye known as methylene blue was monitored under UV and Vis irradiation and showed that the micrometer‐sized structures consisting of TiO2 nanoparticles exhibited a similar photocatalytic activity to submicrometer‐sized structures consisting of TiO2 nanoparticles prepared without TEA.  相似文献   

17.
Titanium nitride‐coated cubic boron nitride (TiN/cBN) composite powders were prepared by nitridizing TiO2/cBN powders in a NH3 flow at 950°C. The TiO2/cBN powders were synthesized via a sol‐gel process using tetra‐butyl titanate and concentrated‐HNO3‐treated BN powders as starting materials. The techniques of XRD, SEM, TEM, FT‐IR, and TG‐DTA were used to characterize the products and their intermediates. The cBN powders were uniformly coated with TiN nanoparticles. During the nitridization, the morphology of the TiO2/cBN powders is unchanged. The TiN/cBN powders can be used as starting materials to prepare polycrystalline cBN compacts, or as reinforcements to strengthen metal‐matrix composites.  相似文献   

18.
热水溶液中钛酸锶晶粒的结晶过程   总被引:6,自引:0,他引:6  
研究了以TiCl4水解得到的H4TiO4胶体作为钛源,在热水溶液中制备SrTiO3晶粒的结晶过程,TEM和XRD结果表明,其结晶过程主要包括3个阶段,第1阶段主要是SrTiO3晶核的形成过程;第2阶段主要是SrTiO3晶粒的配向聚集生长过程;第3阶段主要是SrTiO3晶粒的溶解结晶过程,其中第1阶段的控制步骤为H4TiO4胶体的溶解,第2阶段中晶粒的配向聚集生长在短时间内即可完成,很快进入第3阶段小晶粒的溶解和大晶粒的重结晶过程,该阶段反应速度慢,需要较长时间才能得到结晶完好的晶粒,在热水溶液中以H4TiO4胶体作为钛源制备SrTiO3晶粒关键在于控制结晶过程的第1阶段和第2阶段。  相似文献   

19.
介绍钛酸锌(ZnO-TiO2)体系几种晶相,探讨了近年来合成钛酸锌粉体的各种方法,尤其对化学液相共沉淀法和溶胶-凝胶法合成钛酸锌粉体作了较详细的阐述,并指出可能合成钛酸锌的其他方法.  相似文献   

20.
《Ceramics International》2020,46(4):4870-4877
SiO2–C precursors with various surface areas were derived from tetraethyl orthosilicate and phenolic resin as Si and C sources, respectively, by a modified sol–gel process using the in situ precipitation of phenol resin in a prepared wet gel. The surface area of the SiO2–C precursors was varied from 20 to 175 m2/g by changing the C/Si molar ratio in the preform. β-SiC powders were synthesized using carbothermal reduction in vacuum at the temperature range of 1200–1600 °C. The effects of the temperature and heat treatment time as well as that of the surface area of the preform on the formation of β-SiC powders were studied. It was determined that the formation of β-SiC started at 1200 °C and was considerably promoted as the heat treatment temperature and time further increased during the carbothermal reduction of SiO2–C preforms with high surface area. When high surface area SiO2–C preforms were used, highly crystalline SiC powders were synthesized at 1600 °C in vacuum with a high yield of 85%.  相似文献   

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