共查询到19条相似文献,搜索用时 171 毫秒
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采用溶胶-凝胶化学法合成了Ca3Co4O9热电氧化物粉末,分别采用陶瓷烧结工艺方法和放电等离子烧结(Spark Plasma Sintering,SPS)的方法制备了Ca3Co4O9热电氧化物块体材料.利用X射线衍射XRD、扫描电子显微镜SEM和电输运参数测试仪分析了所得样品的物相、微观组织结构、晶粒取向度和电输运性能.结果表明,不同制备方法均可得到纯相的Ca3Co4O9热电氧化物块体材料;通过陶瓷烧结工艺方法制备的Ca3Co4O9热电氧化物块体晶粒取向度较低,但随着成型压力的增加而提高;SPS烧结的方法制备的Ca3Co4O9热电氧化物块体晶粒取向度最高;试样电性能随着晶粒取向度的提高逐渐提高,其中SPS烧结方法制备的块体材料电性能最高,在测试温度最高点700℃时功率因子达3.85 μWmK-2,远高于普通烧结试样. 相似文献
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多晶YAG陶瓷的制备及力学性能 总被引:25,自引:7,他引:18
本实验采用共沉淀方法制备YAG微粉 ,Al和Y元素分布均匀 ,在 90 0℃煅烧 2h即可全部转变为YAG粉体 ,无过渡相 .15 0 0℃热压 1h可获得致密烧结体 ,其抗弯强度为 2 45MPa ,断裂韧性为 2 .0MPa·m1 /2 ,晶粒大小为 3~ 6μm ;14 0 0℃放电等离子烧结 5min可获得相对密度为 93 %的烧结体 ,其抗弯强度为 3 4 8MPa,断裂韧性为 2 .1MPa·m1 /2 ,晶粒大小为 1~ 2 μm . 相似文献
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溶胶-凝胶法制备巨介电常数材料CaCu3Ti4O12 总被引:3,自引:0,他引:3
通过溶胶-凝胶法制备CaCu3Ti4O12干凝胶,再经700~900℃,6~10h预烧和950~1 100℃,16~20h烧结,成功制备了CaCu3Ti4O12粉体和CaCu3Ti4O12巨介电常数陶瓷材料.用X射线衍射、扫描电镜分别确定了样品的结晶性能和形貌.用阻抗分析仪在10~106Hz范围内测试了陶瓷样品的介电性能.结果表明:粉体的结晶性能与煅烧温度有关,陶瓷介电性能与其晶粒大小有关.相对于传统固相反应合成法制备的粉体和陶瓷,粉体的预烧和陶瓷的烧结温度都有明显降低,烧成温度至少降低100℃.在800℃预烧的CaCu3Ti4O12粉体并在1 100℃温度下烧结制备的陶瓷,其介电常数可达194753. 相似文献
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采用微波加热法合成了稀土La掺杂的Ca3-xLaxCo4O9材料的前驱粉末,进一步制备了热电材料烧结体.通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)等对材料的微观结构进行了研究,通过电导率的测量、Seebeck系数以及热导率的计算研究了材料的热电性能.实验结果表明,微波加热法可以在较短的时间内制得Ca3-xLaxCo4O9粉体,微波烧结方法时间短,效率高,并且晶粒生长完善且晶粒细小.Ca3-xLCo4O9热电材料的微观结构为片状结构,晶粒生长完整. 相似文献
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采用非氧化物AlN和Re2O3作为复合烧结助剂(Re2O3-La2O3与Y2O3)进行碳化硅液相烧结得到了致密的烧结体.烧结助剂占原料粉体总质量的20%,其中:AIN与(La0.5Y0.5)2O3的摩尔比为2:1,在30MPa压力下,1850℃保温0.5h热压烧结的碳化硅陶瓷,抗弯强度>800MPa,断裂韧性>8MPa·m1/2,明显高于同组分1 950℃无压烧结0.5h的碳化硅陶瓷的抗弯强度(433.7MPa)和断裂韧性(4.8MPam·m1/2.热压烧结的陶瓷晶粒呈单向生长,断裂模式为沿晶断裂.同组分无压烧结碳化硅陶瓷的显微结构可以观察到核壳结构. 相似文献
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以二次干燥化学共沉淀法制得高密度前驱体Ni0.8Co0.2(OH)2,再与LiNO3混合,经600℃恒温6 h,800℃恒温24 h两个恒温阶段烧结,得到高密度LiNi0.8Co0.2O2,探讨了锂源、镍源、Li/(Ni+Co)摩尔比、合成温度等因素对产品的影响,优化了LiNi0.8Co0.2O2的合成工艺。所得非球形LiNi0.8Co0.2O2粉末振实密度高达3.15 g/cm3,大幅度地提高正极材料的体积比能量。X射线衍射分析表明,合成的LiNi0.8Co0.2O2具有规整的层状NaFeO2结构,充放电测试表明,材料具有良好的电化学性能。 相似文献
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本实验采用溶胶-凝胶法制备了Ca3Co4O9陶瓷,寻求了其合适的制备工艺,并对陶瓷的显微结构、物相组成、元素组成等进行了表征测试.实验结果表明:煅烧温度为800~900 ℃时均能得到纯相Ca3Co4O9;Ca3Co4O9为取向无规则层片状组织,颗粒尺寸均匀,为2 μm左右;样品的致密度不高,气孔率相对较大. 相似文献
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Photoluminescence Properties of Nanocrystalline ZnO Ceramics Prepared by Pressureless Sintering and Spark Plasma Sintering 总被引:3,自引:1,他引:2
Nanocrystalline ZnO ceramics with grain sizes of ∼100 nm were prepared by pressureless sintering at 800°C for 2 h and spark plasma sintering (SPS) at 550°C for 2 min, respectively. Excellent green emission properties were obtained in the ZnO ceramic prepared by the SPS process and in the pressureless-sintered ZnO ceramic prepared at 1000°C for 2 h, which are attributed to the vacuum ambience of the SPS process and the sublimeness of the interstitial Zn at >900°C in air, respectively. 相似文献
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Yuheng Liu Yuanhua Lin Zhan Shi Ce-Wen Nan Zhijian Shen 《Journal of the American Ceramic Society》2005,88(5):1337-1340
The precursor powders of Ca3 Co4 O9 were synthesized by a sol–gel method. The results of X-ray diffraction and thermogravimetric and differential thermal analyses patterns indicate that pure Ca3 Co4 O9 powders could be obtained by calcining the precursor at 800°C for 2 h. High dense Ca3 Co4 O9 ceramic samples (∼99% of theoretical density) were prepared by the spark plasma sintering (SPS) method. Compared with the conventional sintering (CS), the SPS samples exhibit much higher electrical conductivity and power factor which are respectively about 118 S/cm and 3.51 × 10−4 W·(m·K2 )−1 . The SPS method is greatly effective for improving the thermoelectric properties of Ca3 Co4 O9 oxide ceramics. 相似文献
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D. Demirskyi T.S. Suzuki S. Grasso O. Vasylkiv 《Journal of the European Ceramic Society》2019,39(4):898-906
Microstructure evolution in bulk hafnium diboride ceramics prepared by spark plasma sintering in flash regime was compared with conventional spark plasma sintering. The conventional and flash spark plasma sintering resulted in ceramics with a high relative density exceeding 96% of their theoretical density. A remarkably fine grain size distribution was noticed for the specimen prepared in the flash regime. This atypical microstructure evolution provides a possible insight into the mechanism of flash sintering for conductive bulks. The room temperature flexural strength of the hafnium diboride processed by flash SPS was 650 MPa which is 140 MPa higher than the sample produced by conventional SPS. 相似文献
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以AlN粉末为原料、Y2O3粉末为烧结助剂,分别在氮气气氛下和真空气氛下,采用放电等离子烧结方法在1700℃、25MPa条件下保温10min制备AIN陶瓷。X-射线衍射、扫描电镜和X-射线光电子能谱分析表明:不同烧结气氛下制备的AlN陶瓷的结构和体积电阻率各有不同。真空气氛AlN陶瓷与氮气气氛AlN陶瓷相比较,除舍有主晶相AlN和第二相Y3Al5O12外,还含有微量Al2Y相。正是由于微量Al2Y相的存在,使得真空气氛下得到的AlN陶瓷比氮气气氛下得到的A1N陶瓷的体积电阻率低约2个数量级。 相似文献
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《Journal of the European Ceramic Society》2017,37(5):2099-2104
Barium strontium titanate (Ba0.3Sr0.7TiO3, BST) ceramics have been prepared by conventional sintering (CS) and spark plasma sintering (SPS). The effects of phase constitution and microstructure on dielectric properties, electrical breakdown process and energy storage properties of the BST ceramics were investigated. The X-ray diffraction analysis and dielectric properties measurements showed that the cubic and tetragonal phase coexisted in the SPS sample while the CS sample contained only tetragonal phase. Much smaller grain size, lower porosity, fewer defects and dislocation were observed in SPS samples, which greatly improved the electrical breakdown strength of the Ba0.3Sr0.7TiO3 ceramics. The enhanced breakdown strength of the SPS samples resulted in an improved maximum electrical energy storage density of 1.13 J/cm3 which was twice as large as that of the CS sample (0.57 J/cm3). Meanwhile, the energy storage efficiency was improved from 69.3% to 86.8% by using spark plasma sintering. 相似文献
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研究了硼硅酸盐玻璃主要成分(SiO2、Na2O、B2O3)对硫酸钡(BaSO4)热稳定性的影响,分析BaSO4分别与SiO2、Na2O、B2O3的混合物在不同温度(800~1 200℃)煅烧后的物相组成、显微结构、硫含量和拉曼光谱。结果表明:当BaSO4:SiO2摩尔比为7.5:92.5 (样品A)时,在温度低于1 200℃煅烧后其物相均为BaSO4和SiO2,温度达到1 200℃时出现了少量硅钡石(BaSi2O5)相;当BaSO4:SiO2:Na2O为7:86:7 (样品B)时,在800℃煅烧后即出现了少量BaSi2O5相,当温度达到1200℃时样品主要物相为BaSi2O5和方石英,硫含量明显减少;当BaSO4:SiO2:Na2O:B2O3为5.5:67.5:6.5:21.5 (样品C)时,在800~1 200℃均为BaSO4和SiO2,在1 200℃保温2h后,BaSO4和SiO2的衍射峰基本消失。低熔点的Na2O和B2O3的引入促进了BaSO4的分解,在1 200℃煅烧后,样品A、B、C中SO4四面体的拉曼特征峰依次减弱。 相似文献
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J.G. Noudem 《Journal of the European Ceramic Society》2009,29(12):2659-2663
Processing of textured Ca3Co4O9 (Ca349) thermoelectric ceramics with a good platelet orientation by spark plasma sintering (SPS) consolidation is reported. Two configurations wherein: (i) the oxide powder, being directly introduced into the graphite mould and (ii) placing a compact pellet prepared from the oxide powder in the centre of the mould have been investigated. The free deformation configuration route is found to improve the microstructure and transport properties of Ca3Co4O9 TE oxides. The material prepared exhibited a better performance than the sample obtained by conventional SPS way. 相似文献