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Xiang J.-Y.,University of Science and Technology Beijing | Chen S.-H.,University of Science and Technology Beijing | Huang J.-H.,University of Science and Technology Beijing | Liang W.-J.,University of Science and Technology Beijing | And 3 more authors.
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2012

The synthesis kinetics and phase structure of La 2(Zr 0.7Ce 0.3) 2 O 7 (LZ7C3) ceramic was investigated. The preparation composition was designed according to the mass loss in the synthesis process. LZ7C3 powder was prepared successfully by a solid state reaction method and its atom ratio of La:Zr:Ce is close to the theory value of 10:7:3. The phase composition, microstructure, and thermophysical properties of the powder were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), the laser-flash method and the pushing-rod method. XRD results reveal that LZ7C3 is a mixture of La 2Zr 2O 7 (LZ) with pyrochlore structure and La 2Ce 2O 7 (LC) with fluorite structure, and its main phase is the LZ solid solution. The thermal conductivity of LZ7C3 decreases gradually with increasing temperature; at 1473 K its value is 0.79 W·m -1·K -1, which is almost 50% lower than that of LZ. The thermal expansion coefficient is 20% larger than that of LZ, and its value is 11.6×10 -6 K -1 at 1473 K. These results show that LZ7C3 ceramic can be explored as a novel prospective candidate material for use in new thermal barrier coating systems in the future. Source


Xiang J.,University of Science and Technology Beijing | Chen S.,University of Science and Technology Beijing | Huang J.,University of Science and Technology Beijing | Liang W.,University of Science and Technology Beijing | And 3 more authors.
Journal of Rare Earths | Year: 2012

La 2(Zr 0.7Ce 0.3) 2O 7 (LZ7C3) ceramic was synthesized by solid state reaction with La 2O 3, ZrO 2 and CeO 2 as starting materials. The synthesis kinetics, phase structure, mass loss and microstructure were studied by thermo gravimetric-different thermal analyzer (TG-DTA), X-ray difference (XRD) and scanning electron microscopy (SEM). The thermal conductivity and thermal expansion coefficient were measured by laser-flash method and pushing-rod method, respectively. XRD results showed that LZ7C3 was a mixture of La 2Zr 2O 7 (LZ, pyrochlore) and La 2Ce 2O 7 (LC, fluorite). The lowest synthesis temperature and time of LZ7C3 were 1400°C and 5 h. There were no peaks of La 2O 3 when the powder granularity was about 0.82 μm in the synthesis process. The atom ratio La:Zr:Ce of prepared LZ7C3 powder was very close to 10:7:3 which was the theory value of LZ7C3. The thermal conductivity of LZ7C3 decreased gradually with the temperature increased up to 1200°C, and was located within 0.79 to 1.02 W/(m K), which was almost 50% lower than that of LZ, whereas its thermal expansion coefficient was larger and the value was 11.6×10 -6 K -1. Source


Huang W.,Beihang University | Zhu Y.,Beihang University | He J.,Beijing Golden Wheel Special Machine Co. | Wang R.-J.,Beijing Golden Wheel Special Machine Co.
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2010

The preparation process of nano-YSZ thermal spraying powders was investigated on the excellent performance of nano coating. The agglomerated powders were prepared by spray-drying. The flow ability, free holding density and microstructure of agglomerated powders were tested and analyzed by Hall funnel method and scanning electron microscopic respectively. The result shows that the higher solid content is, the better flow ability and free holding density of powders they will be. However, an overhigh solid content will affect the granulation results. Maintaining a solid content, flow ability of powders is better with moderate binder content. To gain the agglomerated powders of better properties, the optimum follow-up process is the plasma densification process with current 300A and voltage 40V. Source


Fu B.,Beijing Golden Wheel Special Machine Co. | Wang R.,Beijing Golden Wheel Special Machine Co. | Shi M.,Beijing Golden Wheel Special Machine Co. | Qu Y.,Beijing Golden Wheel Special Machine Co.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2015

Burn-resistant coatings were deposited on TC11 titanium alloys by Micro-arc ion surface modification technology. The SEM, TEM and the X-ray diffraction technologies were employed to analyze microstructure and phases of the coating. The combustion parameters of TC11 titanium alloys and the fire-resistant performance of the coatings were measured by titanium fire melt liquid-drop method experimental rig. The results showed that the coating contained TiZr amorphous phases and displayed rather dense, while the serviceability temperature under 700 ℃ the coating had fire-resistant performance. The burn-resistant coatings absorbed energy,and reduced energy which absorbed by substrate. In the same time, these coatings prevent titanium alloy from meeting oxygen. ©, 2015, Harbin Research Institute of Welding. All right reserved. Source

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