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Xiao Z.,Jingdezhen Ceramic Institute | Xiao Z.,Jiangxi Key Laboratory of Advanced Ceramic Materials | Zhu L.,Yulin Normal University | Wang S.,Southwest forestry University
Advanced Materials Research | Year: 2012

Lithium carbonate, zinc oxide and silica as the main raw materials, potassium oxide and sodium as flux, phosphorus pentoxide as nucleating agent, the glass in Li 2O-ZnO-SiO 2 was synthesized by conventional melt cooling method and then converted to glass-ceramics. The crystallization behavior, microstructure and thermal expansion coefficient of the resulting glass-ceramics were investigated by XRD, SEM and thermal performance test. The results show that the Tg of the matrix glass is about 508°C, initial crystallization temperature is about 620°C. When the crystallization temperature ranges from 650°C to 750°C, the main crystal phase is Li 2ZnSiO 4. Increasing crystallization temperature to 850°C, much cristobalite crystals is formed. Owing to the high TEC of the cristobalite, the glass-ceramics with TEC of 12.27×10 -6°C -1 were obtained, which is matched with the TEC of stainless steel SAE 1010. Source


Wang S.,Jingdezhen Ceramic Institute | Jiang W.,Jingdezhen Ceramic Institute | Jiang W.,Jiangxi Key Laboratory of Advanced Ceramic Materials | Feng G.,Jingdezhen Ceramic Institute | And 3 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

Zircon whiskers were prepared via a non-hydrolytic sol-gel method with anhydrous zirconium tetrachloride as zirconium source, tetraethylorthosilicate as silicon source, lithium fluoride as a mineralizer, ethanol as a solvent and anhydrous zirconium fluoride as a whisker growth promoter. The zircon dry gel annealed in nitrogen atmosphere was characterized by thermogravimetric-differential thermal analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. The influences of molding pressure and amount of ZrF4 on the formation of zircon whiskers were investigated. In addition, the formation mechanism of zircon whisker was also discussed. The results show that heat treatment in nitrogen atmosphere does not hinder the synthesis of zircon at a low temperature. It is ineffective to grow zircon whisker in one-dimension either at rather high/low molding pressure or in the presence of more/less ZrF4. The well-developed zircon whiskers with the diameter of 0.2-0.4 μm and the aspect ratio of 15-30 can be obtained at the molding pressure of 2 MPa and the amount of ZrF4 of 10%. ©, 2015, Chinese Ceramic Society. All right reserved. Source


Zhong X.,Jingdezhen Ceramic Institute | Lu X.,Jingdezhen Ceramic Institute | Cao C.,Jingdezhen Ceramic Institute | Chen Y.,Jingdezhen Ceramic Institute | And 2 more authors.
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2015

Submicron spherical CoAl2O4 pigments were hydrothermal synthesized using CoCl2· 6H·O and AlCl3 as raw materials, NaOH as the precipitant and diethanolamine (DEA) as capping agent, respectively. The effect of the concentration of raw materials, the ratio of nCo/nAl and the amount of DEA on the phase composition, particle size and morphology as well as the chroma of the as-prepared pigments was investigated by means of XRD, TEM and calorimetric analysis. The results show that submicron spherical CoAl2O4 pigments with size in a range of 100-230 nm could be synthesized under the conditions of nCo/nAl=1:2, Co2+ concentration 0.05 mol/L and DEA 12%(V/V). The formation of spherical particles was analyzed from the point of view of kinetically controlled crystal growth in the presence of DEA. It follows that during the nucleation and growth process of the crystalline particles, DEA molecules can be adsorbed onto the edges and vertices of the particles in a highly oriented manner thus causing steric hindrance, which enable the spherical growth of the crystalline particles to be possible. © Copyright. Source


Wang S.-H.,Jingdezhen Ceramic Institute | Jiang W.-H.,Jingdezhen Ceramic Institute | Jiang W.-H.,Jiangxi Key Laboratory of Advanced Ceramic Materials | Feng G.,Jingdezhen Ceramic Institute | And 3 more authors.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2014

Zircon whisker was synthesized at 700℃ via non-hydrolytic Sol-Gel method using anhydrous zirconium tetrachloride (ZrCl4) as zirconium source, tetraethylorthosilicate (TEOS) as silicon source, lithium fluoride (LiF) as mineralizer, ethanol as solvent and carbon black as reducing agent. Thermogravimetric analysis and differential thermal analysis (TG-DTA), X-ray diffraction analysis (XRD) and transmission electron microscope (TEM) were employed to characterize the influences of adding ways and amount of carbon black on the synthesis and morphology of zircon whisker. The results show that the carbon black added in form of suspension is favorable to the one-dimension growth of zircon. When 6wt% carbon black is added, optimized zircon whiskers are achieved along the growth direction of [001], which diameter and aspect ratio are in the range of 30-90 nm and 6-15|, respectively. Because of carbon black reacting with oxygen to form carbon dioxide and monoxide, the adding way and amount of carbon black efficiently regulate the oxygen partial pressure in the reaction system. Reducing oxygen partial pressure can form more SiF4 gas, which is the basis of one-dimensional direction growth of zircon. However, excessively low oxygen partial pressure is against the ZrSiO4 formation. Therefore, appropriate oxygen partial pressure can promote the growth of zircon whisker. Source


Zhang T.,Jingdezhen Ceramic Institute | Jiang W.,Jingdezhen Ceramic Institute | Jiang W.,Jiangxi Key Laboratory of Advanced Ceramic Materials | Feng G.,Jingdezhen Ceramic Institute | And 3 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

Zircon whiskers were synthesized by a non-hydrolytic sol-gel process combined with a molten salt method with anhydrous zirconium tetrachloride as zirconium source, tetraethylorthosilicate (TEOS) as silicon source, anhydrous ethanol as a solvent, sodium molybdate as a molten salt. The phase transition of zircon dry gel in the presence of the molten salt as well as the influences of molten salt, heat treatment temperature and holding time on the one-dimensional preferential growth of zircon crystal were investigated. The results show that the presence of molten salt can reduce the synthesis temperature of zircon and promote the one-dimensional growth of zircon. The zircon whiskers along the growth direction of [001], the diameter of 50-100 nm and the aspect ratio of 20-30 can be synthesized at 850 ℃ for 3 h. ©, 2015, Chinese Ceramic Society. All right reserved. Source

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