Cathode materials for La0.995Ca0.005NbO4 proton ceramic electrolyte

The study presents the chemical and mechanical compatibility of the proton conducting electrolyte La_0.995Ca_0.005NbO₄ (LCNO) with the LSM, LSCM and BSCF cathodes and the electrochemical performance of symmetrical cells based on LCNO. After annealing at high temperature the electrolyte-cathode mixtures in air and wet air, the obtained products were analyzed by X-ray powder diffraction (XRPD). The microstructure of the cathode and electrolyte materials and the interfaces were observed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). The results show that LSCM cathode is chemically and mechanically stable with the LCNO electrolyte although the BSCF cathode reacts with it. Cation diffusion was observed between LSM cathode and LCNO electrolyte after the heat treatment of their mixture at T = 1150 °C. The electrochemical study performed on symmetrical cells revealed that the LSCM cathode presents the lowest value of area specific resistance (ASR) compared to the ones of the LSM and BSCF cathodes: ASR_LSCM = 35 Ω cm²; ASR_LSM = 57 Ω cm²; ASR_BSCF = 416 Ω cm² (in humidified air at 750 °C). Finally, a CER-CER approach was used in order to minimize the polarisation resistance of the LSM cathode by mixing LSM and LCNO in different volumetric ratios. The lowest value of ASR for LSM-based composite cathode was obtained by adding 50 vol.% of LCNO to LSM cathode (ASR_LSM/LCNO = 22 Ω cm² in humidified air at 750 °C).     

Consteel交流电弧炉电极调节系统中Tagliaferri电液伺服阀的研究

以Consteel交流电弧炉的电极调节系统为研究对象,重点对Tagliaferri电液伺服阀的结构、工作原理及动态静态特性进行了研究和分析,进一步深入地掌握了其结构特点和输入输出特性,充分认识其结构简单、响应速度快、工作稳定等优良特性,以便更合理地使用该伺服阀,以期进一步提高国内Consteel交流电弧炉电极调节系统的...     

Novel Nd2WO6-type Sm2−xAxM1−yByO6−δ (A = Ca, Sr; M = Mo, W; B = Ce, Ni) mixed conductors

In the present work, we have explored novel Nd₂WO₆-type structure Sm_2−xA_xM_1−yB_yO_6−δ (A = Ca, Sr; M = Mo, W; B = Ce, Ni) as precursor for the development of solid oxide fuel cells (SOFCs) anodes. The formation of single-phase monoclinic structure was confirmed by powder X-ray diffraction (PXRD) for the A- and B-doped Sm₂MO₆ (SMO). Samples after AC measurements under wet H₂ up to 850 °C changed from Nd₂WO₆-type structure into Sm₂MoO₅ due to the reduction of Mo^VI that was confirmed by PXRD and is consistent with literature. The electrical conductivity was determined using 2-probe AC impedance and DC method and was compared with 4-probe DC method. The total electrical conductivity obtained from these two different techniques was found to vary within the experimental error over the investigated temperature of 350-650 °C. Ionic and electronic conductivity were studied using electron-blocking electrodes technique. Among the samples studied, Sm_1.8Ca_0.2MoO_6−δ exhibits total conductivity of 0.12 S cm⁻¹ at 550 °C in wet H₂ with an activation energy of 0.06 eV. Ca-doped SMO appears to be chemically stable against reaction with YSZ electrolyte at 800 °C for 24 h in wet H₂. The ionic transference number (t_i) of Sm_1.9Ca_0.1MoO_6−δ in wet H₂ at 550 °C (pO₂ = 10^−25.5 atm) was found to be about 0.012 after subtraction of electrical lead resistance from the 2-probe AC data and showed predominate electronic conductors.     

Microstructural and electrochemical impedance study of nickel-Ce0.9Gd0.1O1.95 anodes for solid oxide fuel cells fabricated by ultrasonic spray pyrolysis

Optimization of the electrode microstructure in a solid oxide fuel cell (SOFC) is an important approach to performance enhancement. In this study, the relationship between the microstructure and electrochemical performance of an anode electrode fabricated by ultrasonic spray pyrolysis was investigated. Nickel-Ce_0.9Gd_0.1O_1.95 (Ni-CGO) anodes were deposited on a dense yttria stabilized zirconia (YSZ) substrate by ultrasonic spray pyrolysis, and the resulting microstructure was analyzed. Scanning electron microscope (SEM) examinations revealed the impact of deposition temperature and precursor solution concentration on anode morphology, particle size and porosity. The electrochemical performance of the anode was measured by electrochemical impedance spectroscopy (EIS) using a Ni-CGO/YSZ/Ni-CGO symmetrical cell. The deposited anode had a particle size and porosity in ranging between 1.5-17 μm and 21%-52%, respectively. The estimated volume-specific triple phase boundary (TPB) length increased from 1.37 × 10⁻³ μm μm⁻³ to 1.77 × 10⁻¹ μm μm⁻³as a result of decrease of the particle size and increase of the porosity. The corresponding area specific charge transfer resistance decreased from 5.45 ohm cm² to 0.61 ohm cm² and the activation energy decreased from 1.06 eV to 0.86 eV as the TPB length increased.     

交流电弧炉系统建模与仿真研究

针对电弧V-I特性曲线拟合法提出了改进思路,并对实际的交流电弧炉系统提出了建模方案和具体建模实现,并进行了交流电弧炉系统仿真分析。最终的仿真结果证明了建模方案的有效性,其模型误差度仅在4%左右。     

应用交-交变频技术实现卷扬电机的重载起动

本文给出了卷扬机的几种起动方式,分析了其特性,着重介绍了软启动。本文的目的是解决卷扬机的重载起动,通过交-交变频的方法来实现。     

60m涂层线烘箱技术改造

通过对涂层线烘箱电热管接线方式和控制方式的技术改造,达到烘箱内温度平稳调节,实现亲水铝箔高质量的热处理,保持生产设备持续、高效、经济地运行,改造后实践证明取得了很好的经济效益。     

基于温度补偿控制的水电阻软启动器的建模与仿真

针对大功率电动机在直接启动过程中启动电流过从而对电网产生较大的冲击的问题,设计一种基于温度补偿控制的水电阻调速器的大功率转子绕线异步电机软启动及调速系统.介绍水电阻器的结构以及原理,采用ARPS经验公式分析温度变化对电解质溶液的电阻率影响,建立基于水电阻调速的异步电动机调速系统动力学数学模型,提出了温度补偿的控制方法,通过Matlab/Simulink仿真验证模型及算法的有效性.仿真结果表明:采用温度补偿的水电阻器调速系统启动电流较小,启动转矩平滑,调节速度快.     

埋地钢质管道交流杂散电流腐蚀规律研究

通过室内模拟实验建立了交流电流密度与破损面积、土壤电阻率、交流干扰电压以及防腐层电阻率之间的数学模型,从而间接获取交流电流密度,并研究了交流电流密度对腐蚀速率的影响。通过CDEGS软件模拟仿真,得到了并行长度、电流等级、距离、土壤电阻率等参数对交流干扰沿管道分布的作用。结果表明,破损面积、交流干扰电压、土壤电阻率、防腐层电阻率对交流杂散电流密度具有显著的影响。电流密度小于3 mA/cm²时,交流电流腐蚀危害性很小;在3~10 mA/cm²时,腐蚀危害性较大;大于10 mA/cm²时,交流腐蚀危害性很大。     

埋地管道交流干扰与阴极保护相互作用研究进展

系统地综述了交流干扰对阴保电位、阴保电流密度、牺牲阳极电位、牺牲阳极消耗速率、牺牲阳极效率等参数的影响,同时阐述了交流干扰下阴保评价准则及交流腐蚀机理的最新研究成果。最后指出了目前研究存在的主要问题,展望了该研究领域的发展趋势。