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共沉淀法制备Al_2O_3-YAG复相陶瓷及其显微结构研究 总被引:1,自引:0,他引:1
用共沉淀法制备了Al2O3-YAG复合粉体,YAG的结晶温度在1000℃左右.共沉淀法 制备的Al2O3-YAG复合粉体经1550℃热压烧结,获得致密烧结体,YAG的加入量对烧结温度 的影响不大. Al2O3-5vol%YAG复合材料的抗弯强度为604MPa,断裂韧性为5.0MPam1/2; Al2O3-25vol%YAG复合材料的抗弯强度为611MPa,断裂韧性为45MPam1/2.所有这些数据 都高于单相Al2O3陶瓷的力学性能,说明YAG的加入有利于A12O3陶瓷力学性能的提高. 通过显微结构观察发现:大的YAG颗粒位于Al2O3晶界上,小的YAG颗粒位于Al2O3晶粒 内.在 Al2O3-5vol%YAG复合材料中,许多小的白色区域存在于 Al2O3晶粒内,这可能和较低 的Y2O3含量有关. 相似文献
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α—Al2O3微滤膜的烧结过程动力学 总被引:5,自引:0,他引:5
用悬浮粒子烧结法在管状α-Al2O多孔支撑体上制备α-Al2O3微滤膜,研究了不同烧结制度对α-Al2O3微波膜性能的影响,得到了获得高质量α-Al2O3膜的烧结条件,运用烧结理论模型探讨了微滤膜的烧结机理,计算了膜烧结过程的反应速率常数箐表现活化能。 相似文献
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本文利用透射电镜(TEM)及能量色散X射线衍射分析(EDAX)技术对激光合成的Al2O3-WO3陶瓷材料进行分析.TEM分析表明,在Al2O3-WO3材料的胞状结构中,Al2O3形成柱状单晶且Co轴平行生长轴,Al2(WO4)3及AlxWO3位于Al2O3柱状晶间界;非平衡相AlxWO3中存在畴及超晶格结构,Al3+对WO3母体网格A位占位是有序的.EDAX结果则指出合成材料Al2O3晶粒中W杂质的浓度随配料WO3含量的增加而增大;样品合成过程中激光功率从最高值连续降低至0瓦可减少Al2O3晶粒W的掺入量;高温下对合成样品长时间热处理可使W杂质从Al2O3中释放出.材料电性质测试结果表明,材料电阻率与其中Al2O3晶粒W含量紧密相关,W的含量越高,材料电导率越大. 相似文献
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以工业氢氧化铝粉为原料,对其进行了添加α-Al2O3晶种的处理,研究了粉体添加晶种前后转相温度的变化情况。氢氧化铝原料粉在1250℃转变为α-Al2O3,而用湿磨工艺混入5wt%的α-Al2O3作为晶种后,在900℃相转变开始发生,到1100℃转相完成。粉体平均粒径0.3μm,优于原料粉的转相结果。 相似文献
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本文探讨了Si及α-Al2O3超细粉对Al2O3-ZrO2-C系材料显微结构的影响。认为在Al2O3-ZrO2-C系材料中同时加入Si和α-Al2O3超细粉,Si粉除了与C生成了SiC纤维外,其反应产物SiO2还与α-Al2O3超细粉及ZrO2生成了莫来石(A3S2)和Al2O3-ZrO2-SiO2(AZS)固溶体,这些新生成的矿物相对试样的显微结构产生重要的作用。 相似文献
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Y2O3添加剂对ZrO2超微粉体性质的影响 总被引:2,自引:0,他引:2
添加0-6mol%Y2O3的ZrO2超微粉体由化学共沉淀法制备,系统地研究了添加剂对粉体粒子粒径,表面性质和团聚状态的影响,结果表明,添加Y2O3组元,使制备的ZrO2粉体粒子粒径减小,对粒子的长大趋势可起到抑制作用,但加剧了粉体粒子的团聚,团聚体颗粒变大,团聚强度升高,随着组元添加量的增多,作用加剧。 相似文献
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Synthesis and Properties of Cerium Oxide Nanometer Powders by Pyrolysis of Amorphous Citrate 总被引:9,自引:0,他引:9
CeO2 nanometer powders of different sizes were prepared at low temperature by pyrolysis of amorphous citrate. XRD patterns show that CeO2 is cubic in structure, space group Oh5-FM3M·TEM indicates that the prepared CeO2 is spherical in shape, and the particle size distribution is in narrow range. It was found that calcination temperature is a more important factor affecting the crystallite size of CeO2 than calcining time, the smaller the particle. the bigger the crystallattice distortion, the worse the crystal growth. Solubility test of CeO2 in nitric acid reveals that the surface activity of CeO2 decreases with the increasing particle sizes. IR spectra analysis shows that the absorption of Ce-O bond is shifted to higher energy with the decrease of CeO2 particle sizes. 相似文献
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P. Tartaj C. J. Serna J. S. Moya J. Requena M. Ocaña S. De Aza F. Guitian 《Journal of Materials Science》1996,31(22):6089-6094
The different factors affecting the mechanism of zircon formation from amorphous ZrO2 · SiO2 powders have been studied. It was shown that zircon was formed by solid state reaction between tetragonal zirconia and silica (amorphous and cristobalite). The previously suggested Hedvall effect associated with the crystallization of amorphous silica into cristobalite did not play any role in this reaction. A high degree of Si-Zr mixing in the starting amorphous powders did not affect the mechanism of zircon formation, but speeded up the reaction rate due to the small particle size of the zirconia and silica particles segregated previously to zircon formation. It was also found that the formation reaction was retarded by the presence of carbonaceous species coming from the alkoxide precursors, which were probably retained at grain boundaries after calcination, acting as a diffusion barrier. These factors can explain the observed differences in the temperatures of zircon formation previously reported. 相似文献
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Xiangting DONG Guangyan HONG College of Materials Chemical Engineering Changchun University of Science Technology Changchun China Key Laboratory of Rare Earth Chemistry Physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China 《材料科学技术学报》2005,21(4):555-558
A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope (TEEM) images indicate that the particles are spherical in shape and smaller than 100 nm in size. The crystallite sizes of cubic Ln2O3 have lanthanide shrinking effect, while average crystal lattice distortion rates possess lanthanide swelling effect. The diffraction peak intensity of heavy rare earth oxide nanometer powders is remarkably stronger than that of light rare earth oxide nanometer powders. The variation of diffraction intensity with atomic number presents an inverted W type, forming a double peak structure. Fourier transform infrared (FTIR) spectrums reveal that Ln2O3 nanopowders have higher surface activity than that of ordinary Ln2O3 powders. The UV-vis spectra show that Ln-O bond of these particles is slightly blue-shifted, and its absorption intensity decreases. 相似文献
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采用液相共沉淀法制备了ZAO掺杂半导体粉末材料,系统研究了制备工艺对ZAO粉末红外发射率的影响.借助于TG-DTA、XRD、SEM对材料的热处理温度,晶体结构及表面形貌进行了考察,利用IR-2双波段发射率测量仪对ZAO粉末材料的红外发射率进行了测试.研究结果表明:当反应物终点pH值为8.5、反应时间为2.5h、煅烧温度为800℃,煅烧时间为2h、Al2O3的掺杂量为3%时所得的ZAO粉末的红外发射率最低;ZAO掺杂半导体粉末的晶体结构为ZnO的铅锌矿结构;粒子形状近似为椭圆形,平均粒径为5~10μm;在中红外(3~5μm)和远红外(8~14μm)波段均具有较低的红外发射率. 相似文献
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在自行设计的小型气体水合物反应装置上进行了纳米流体中CO2水合物生成特性的实验研究,探讨了纳米粒子的种类、粒径和质量分数对CO2水合物生成特性的影响。研究发现,与纯水相比,纳米粒子Cu O和Si O2增加了CO2耗气量,但延长了气体水合物生成的诱导时间。金属纳米粒子Cu和金属氧化物纳米粒子Al2O3对CO2水合物生成的诱导时间和耗气量有明显改善。对不同粒径的Al2O3纳米粒子对气体水合物生成特性的研究发现,30 nm的Al2O3纳米流体对水合物生成特性影响最大。与纯水相比,0.1%-30 nm-Al2O3纳米流体中水合物生成的诱导时间缩短了76.9%,耗气量增加了23.2%。CO2水合物耗气量随着Cu粒子质量分数的增加先增加后减少。最后进行了纳米粒子对CO2水合物生成特性的影响的理论分析。 相似文献
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Dianran Yan Yong Yang Yanchun Dong Lei Wang Xueguang Chen Jianxin Zhang Jining He 《Materials Chemistry and Physics》2012
Fe2O3–Al composite powders were deposited onto steel substrate by plasma spraying. The reaction products of the Fe2O3–Al composite powders in the plasma flame and their solidification process were investigated. The results showed that the reaction products of the Fe2O3–Al composite powders in the plasma flame were Fe–Al–O ceramic melt and Fe melt. Fe was not always formed in the reaction products of each composite particle, and the formation of Fe was dependent on the composition distribution and the reaction kinetics process of each composite particle. The composition inhomogeneity, discontinuity and porousness of the composite particles resulted in the difference of the reaction kinetics of each composite particle and the composition difference of the droplets. Hercynite solid solution, Fe, Al2O3 and FeAl phases were formed by non-equilibrium solidification of the Fe–Al–O ceramic melt. For the smaller size droplet, when it spread on the substrate, the spreading droplet was quickly chilled to form equiaxed grains with size of 100–200 nm. Nano-sized or submicron equiaxed grains, nano-sized columnar grains and cellular structure were formed in the larger spreading droplet. Fe rich hercynite solid solution nucleated and grew preferentially and then Al rich hercynite solid solution grew, which form composition segregation in the columnar grains. The main phases in the composite coating were hercynite solid solution. 相似文献
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混合导体氧化物SrFeCo0.5Oy粉末的微波合成与表征 总被引:4,自引:0,他引:4
采用微波加热方法与常规高温固相法合成了Sr-Fe-Co-O系混合导体陶瓷氧化物粉末.利用XRD,TEM/EDX及SEM等测试方法分析与表征粉体.用微波加热合成的粉体颗粒尺寸分布均匀,一次颗粒尺寸较小,结晶度也好于用常规加热合成的粉体.微波加热合成粉体的结晶相结构是钙钛矿结构Sr(Fe,Co)1.5Oy相,并有少量的正交结构相和尖晶石(Co,Fe)3O4相;高温固相法合成粉末由Sr4(Fe,Co)6O13±δ相及少量的Sr(Fe1-xCox)O3-δ相和CoO相组成. 相似文献
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采用溶胶-凝胶法合成了不同粒径的Al2O3-30%(质量分数)TiO2纳米复合粉体,用喷雾干燥法对合成粉体进行喷雾造粒,造粒后的粉体通过等离子喷涂制备Al2O3/TiO2复合涂层,最后对涂层结构和性能进行了表征。涂层结构和形貌分析表明制备的涂层具有微米/纳米复合结构,初始粉体粒径对涂层的结构和致密度影响很小;涂层摩擦学性能测试表明复合涂层的磨损率随初始粉体粒径的增大而减小,初始粉体粒径为100nm左右时,复合涂层的磨损率最低。复合涂层的磨损机制为裂纹扩展导致的磨损剥落。 相似文献