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91.
Saeed Ur Rehman Ahmad Shaur Hye-Sung Kim Dong Woo Joh Rak-Hyun Song Tak-Hyoung Lim Jong-Eun Hong Seok-Joo Park Seung-Bok Lee 《International Journal of Applied Ceramic Technology》2021,18(2):511-524
A dense Ce0.9Gd0.1O2−d (GDC) interlayer is an essential component of the SOFCs to inhibit interfacial elemental diffusion between zirconia-based electrolytes (eg YSZ) and cathodes. However, the characteristic high sintering temperature of GDC (>1400°C) makes it challenging to fabricate an effective highly dense interlayer owing to the formation of more resistive (Zr,Ce)O2 interfacial solid solutions with YSZ at those temperatures. To fabricate a useful GDC interlayer, we studied the influence of transition metal (TM) (Co, Cu, Fe, Mn, & Zn) doping on the sintering and electrochemical properties of GDC. Dilatometry data showed dramatic drops in the necking and final sintering temperatures for the TM-doped GDCs, improving the densification of the GDC in the order of Fe > Co > Mn > Cu > Zn. However, the electrochemical impedance data showed that among various transition metal dopants, Mn doping resulted in the best electrochemical properties. Anode supported SOFCs with Mn-doped, nano, and commercial-micron GDC interlayers were compared with regard to their performance and stability levels. Although all of the SOFCs showed stable performance, the SOFC with the Mn-doped GDC interlayer showed the highest power density of 1.14 W cm−2 at 750°C. Hence, Mn-doped GDC is suggested for application as an effective diffusion barrier layer in SOFCs. 相似文献
92.
Muzhang Huang Xiangyang Liu Yingjie Feng Chunlei Wan Wei Pan Jun Yang Xiaohui Zhao 《Journal of the European Ceramic Society》2021,41(1):526-534
Understanding the effect of nonstoichiometry on material properties is of critical importance for the Thermal Barrier Coatings (TBCs) application. In this work, the effect of nonstoichiometry was systematically investigated in Y3NbO7, a recently identified promising TBCs material for next-generation gas turbine engines. The results show that the nonstoichiometry effect mediates the microstructure, mechanical properties, thermophysical properties, oxygen ionic conductivity and optical transmittance. The results suggest that the oxygen ionic conductivity is correlated to the mass diffusion in the oxygen-deficient fluorite oxides Y1-xNbxO1.5+x. The stoichiometric composition Y3NbO7, with the lowest thermal conductivity and slowest mass diffusion in Y1-xNbxO1.5+x series, is optimal for the TBCs application, which can be of relevance for TBCs material design and coating fabrication. 相似文献
93.
文中针对变电站高压并联电抗器噪声对环境的影响问题及其控制要求,通过实验研究了高压并联电抗器噪声的影响因素及其控制措施。文中采用改进声强法实测了湖北省内15座变电站37组共111台500 kV高压并联电抗器声功率级,并对其进行了分析。测试结果表明,随着运行年限的增加,电抗器最大声功率级逐步增大。由于设备额定容量与额定电压的提高,使用新的绝缘材料和设计方案后,在一定程度上会起到减震降噪作用。同时,电抗器采用散热片四周布置方式,也能实现对噪声的控制。针对高压电抗器的噪声控制,文中从声源控制、传播过程控制角度,提出相应的控制措施。其中,声源主要通过改善材料和设计进行控制。以某500 kV变电站的降噪处理为例,利用SoundPLAN噪声分析软件,提出了隔声屏障控制方案,使噪声平均声压级降低约6 dB(A),从而满足噪声控制的要求。文中的研究内容对于指导变电站的设计及降噪处理具有重要意义。 相似文献
94.
Qiuqiu Lyu Tenglong Zhu Hongxia Qu Zaihong Sun Kaihua Sun Qin Zhong Minfang Han 《Journal of the European Ceramic Society》2021,41(12):5931-5938
Hydrothermal reaction in Cerium and Gadolinium solution as an optimization method is developed and first reported for the densification of gadolinia doped ceria, the barrier layer between Zirconia electrolyte and (La,Sr)(Co,Fe)O3-δ cathode. This method is based on the hydrothermal reaction for nano particles in-situly grown on porous surface, to improve barrier layer density, alongside the sintering of cathode at 1075 °C. As a result, the ohmic resistance is prominently decreased by ~16.4 % at 750 °C for electrolyte supported symmetrical cell. Whereas, the cathode polarization resistance is decreased by as much as a factor of ~3 from 0.3702 Ω·cm2 to 0.1325 Ω·cm2 at 750 °C and . Furthermore, the anode supported cell exhibits higher open circuit voltage, smaller area specific resistance, elevated performance output and less degradation. And this modified barrier layer shows reduced Sr migration in 300 h operation at 750 °C. The hydrothermal reaction is demonstrated to prepare denser and sintering-active barrier layer with faster oxygen ion transfer and better interface connection, with large-scale application prospects and cost-competitiveness. 相似文献
95.
Wen Ma Yuanming Gao Jingxin Zhang Yu Bai Ruiling Jia Hongying Dong Ruijun Wang Manyu Bao 《Journal of the European Ceramic Society》2021,41(4):2734-2745
Srx(Zr0.9Y0.05Yb0.05)O1.95+x (x=1.0, 0.9, 0.8, 0.7) ceramics were prepared by solid state reaction sintering. The sintered Sr1.0(Zr0.9Y0.05Yb0.05)O2.95 is a single-phase solid solution while the sintered Srx(Zr0.9Y0.05Yb0.05)O1.95+x (x=0.9?0.7) are composites, and a significant grain growth inhibition is observed in the sintered Srx(Zr0.9Y0.05Yb0.05)O1.95+x (x=1.0, 0.9). Rare-earth elements distribution in the bulk materials indicates that Yb and Y preferentially substitute Zr-sites in SrZrO3, and the highest solubility of RE2O3 in pure SrZrO3 is ~0.8 mol%. The sintered Srx(Zr0.9Y0.05Yb0.05)O1.95+x have high thermal expansion coefficients up to ~11.0×10?6 K-1 (1200°C). Sr0.8(Zr0.9Y0.05Yb0.05)O2.75 has the lowest thermal conductivity of 1.38 W·m-1·K-1 at 800°C. Srx(Zr0.9Y0.05Yb0.05)O1.95+x (x=1.0, 0.9, 0.8) show no phase transition from 600 to 1400°C, whereas Srx(Zr0.9Y0.05Yb0.05)O1.95+x (x=0.9, 0.8) have excellent high-temperature phase stability over the whole investigated temperature range. Therefore, Srx(Zr0.9Y0.05Yb0.05)O1.95+x (x=1.0, 0.9, 0.8) are considered as promising TBCs materials that might be operated at higher temperatures compared to YSZ. 相似文献
96.
《Journal of the European Ceramic Society》2022,42(8):3559-3569
To explore the mechanism of phase transformation, YTa3O9 was prepared by an integrated one-step synthesis and sintering method at 1500 °C using Y2O3 and Ta2O5 powders as starting materials. High-temperature XRD patterns and Raman spectra showed that a phase transformation from orthorhombic to tetragonal took place in YTa3O9 through the bond length and angle changes at 300–400 °C, which caused a thermal conductivity rise. To inhibit the phase transformation, a high-entropy (Y0.2La0.2Ce0.2Nd0.2Gd0.2)Ta3O9 (HE RETa3O9) was designed and synthesized at 1550 °C using the integrated solid-state synthesis and sintering method. In tetragonal structured HE RETa3O9, phase transformation was inhibited by the high-entropy effect. Furthermore, HE RETa3O9 exhibited low thermal conductivity, and its tendency to increase with temperature was alleviated (1.69 W/m·K, 1073 K). Good phase stability, low thermal conductivity and comparable fracture toughness to YSZ make HE RETa3O9 promising as a new thermal barrier coating material. 相似文献
97.
《Journal of the European Ceramic Society》2022,42(7):3305-3312
Environmental barrier coatings (EBCs) are used in commercial turbine engine applications as protection for ceramic matrix composites, yet the high-temperature water vapor reaction mechanism for EBC materials is not fully understood. Here, the water vapor reaction mechanism for barium strontium alumino-silicate (BSAS), an early generation EBC candidate, was determined from the time and temperature dependences of material loss. BSAS water vapor exposures were performed at 1200 °C, 1300 °C, and 1400 °C for 24, 48, and 72 h, at maximum gas velocities of ~ 240 m/s. FactSage thermodynamic calculations were shown to support the experimental findings, where the steam reaction mechanism consisted of volatilization of all BSAS oxide constituents as gaseous metal hydroxide species, i.e. Ba(OH)2, Sr(OH)2, Al(OH)3, and Si(OH)4 (g). 相似文献
98.
Polynorbornene/sepiolite hybrid nanocomposite films were prepared using polynorbornene dicarboximide and modified sepiolite with 3‐ aminopropyltriethoxysilane (3‐APTES). Exo‐N‐(3,5‐dichlorophenylnorbornene)‐5,6‐dicarboxyimide (monomer) and their copolymers were synthesized via ring‐opening polymerization using ruthenium catalysts. Subsequently, the surface‐modified sepiolite by 3‐APTES was mixed with the polynorbornene copolymers to prepare hybrid nanocomposite films. The modified sepiolite particles were well dispersed in N,N‐dimethylacetamide and distributed randomly throughout the polynorbornene matrix in the hybrid films, which enhanced the dimensional stability and mechanical and oxygen barrier properties of the polynorbornene/sepiolite hybrid nanocomposite films. © 2014 Society of Chemical Industry 相似文献
99.
根据近几年来国家对地下水资源污染防控要求,新建石油化工项目、已建成装置可能产生渗漏、泄漏污染的地下污水管道均需采取防渗措施。为了保护地下水资源,结合工程经验,简单介绍了工程设计中常选择的几种地下污水管道防渗方式,防渗膜、防渗管沟及防渗套管。并叙述了这几种防渗方式的适用条件、优缺点,以及管道发生渗漏后能及时被发现的措施。 相似文献
100.
A vinyl phosphonic acid based flame retardant coating has been applied on the surface of a glass-fibre reinforced epoxy (GRE) composite substrate using a UV polymerisation technique. On exposure to heat the poly (vinyl phosphonic acid) (PVPA) coating thus obtained, intumesces and acts as a thermal insulator, providing active fire protection to the composite structure. Samples with ∼300 and 500 μm thick coatings were prepared. The fire performance of the coated GRE composite was studied by cone calorimetry at 35 and 50 kW/m2 heat fluxes. While the sample with ∼500 μm thick coating did not ignite at both heat fluxes, the one with the ∼300 μm thick coating ignited at 50 kW/m2, however the time-to-ignition was delayed from 60 s in the uncoated sample to 195 s and the peak heat release rate reduced from 572 kW/m2 to 86 kW/m2. The coatings did not peel off when subjected to a tape pull test and resisted cracking/debonding during an impact drop test of up to 5 J energy. However, the coatings are hydrophilic, showing significant mass loss in a water soak test. The improvement of the hydrophobicity of these coatings is a focus of our future research. 相似文献