氧化物陶瓷阻氚涂层的研究进展

利用阻氚涂层(TPB)降低结构材料中的氚损失,是聚变堆发展中的热点研究之一。陶瓷具有低氚渗透性、耐腐蚀性、高硬度和高热稳定性等特性,是目前聚变堆阻氚涂层首选材料。相对于硅化物、钛基等非氧化物陶瓷材料,氧化物陶瓷涂层具有熔点高、化学性质稳定、耐腐蚀性和阻氚渗透因子(PRF)高等优势,因此针对氧化物陶瓷阻氚涂层的研究较多。主要综述了单一氧化物陶瓷、复合氧化物陶瓷阻氚涂层近年来的研究现状与发展,如Y2O3、Er2O3、Al2O3等及其复合氧化物陶瓷材料,其中,因Al2O3及其复合物涂层具有优异的阻氚性能,得到了广泛的关注和研究。重点阐述了制备工艺、基体效应和辐照等影响氧化物陶瓷涂层阻氚性能的因素及氚在材料中的渗透机制,并分析了当前阻氚涂层在材料制备以及模拟服役环境等方面存在的不足与今后的研究重点,指出了未来可能的氧化物陶瓷阻氚涂层,以期为阻氚涂层的研究与后续实验提供一定的方向。     

An SOFC anode model using TPB-based kinetics

Fundamental studies focusing on the electrode kinetics are essential in understanding the fuel cell operation and optimizing the electrode designs. In this study, we determined the triple-phase boundary (TPB)-based kinetics of hydrogen electrochemical oxidation using nickel patterned electrode experimental data and the Butler-Volmer formalism of the oxidation process. The same kinetics are then incorporated in a cermet electrode electrochemical model to estimate the effective TPB density of the nickel/yittrium-stabilized zirconia cermet anode. The kinetics are found to be of the same order of magnitude as previously determined by the microstructure reconstruction of cermet anode. Simulation results further revealed that the effective TPB density is several orders of magnitude lower than the typically reported physical densities of the cermet anode that possibly suggests that only a minor fraction of the physical TPB is actually required or available to produce the cell current at given cell voltage. The effect of various operating conditions on the anode activation overpotential is also investigated and discussed in this study.     

Perceived derived attributes of online customer reviews

The influence of online customer reviews (OCRs) on customers' purchase intention has recently gained considerable attention, in both academic and business communities. Technology allows customers to freely and easily post their comments and opinions online about any product or service; this type of customer review can have a significant effect on customers' purchase decisions. Previous studies, however, have mainly focused on the influence of the virtual attributes of OCRs such as volume and valence on consumers' intentions, while limited attention has been paid to understanding the effects of the derived attributes. This study, thus, aims to understand the impact of the perceived derived attributes of OCRs on customer trust and intention. This study develops a – Perceived Derived Attributes (PDA) - model, based on the inclusion of perceived control from the Theory of Planned Behaviour (TPB) with the Technology Acceptance Model (TAM), in order to investigate the effects of OCRs on customers’ purchasing intention. A total of 489 responses to a survey were collected from users of amazon.com. The findings from this study suggest that customer trust in an e-vendor and their intention to shop online are significantly affected by perceived usefulness, perceived ease of use and perceived enjoyment of OCRs. Furthermore, the sense of control derived from OCRs significantly affects customer intention and significantly affects customer trust in e-vendors, particularly for customers who frequently check OCRs before making a purchase. Clearly, those attributes of OCRs are linked to the development of the shopping environment, which consequently can affect sales.     

Recovery of 137Cs from Laboratory Waste using Solvent Extraction with Sodium Tetraphenylboron (TPB)

The paper describes a method for the recovery of ¹³⁷Cs from an aqueous radioactive laboratory waste solution containing ¹³⁷Cs (2 µg/mL) in the presence of high concentration of Na⁺ using solvent extraction technique. The method comprises of adjustment of pH to the acidic range (pH = 2), contacting the aqueous radioactive solution with sodium tetraphenylboron (TPB) in nitrobenzene, whereby ¹³⁷Cs binds with tetraphenylboron anions and gets separated. Results of this investigation indicate that ¹³⁷Cs could be efficiently and selectively extracted from an aqueous solution media containing high concentration of Na⁺ under mildly acidic pH into an organic phase and back extracted with small volume of 3 M HNO₃, thus enabling concentration. The proposed method was successfully applied in real samples.     

Discrete fracture in high performance fibre reinforced concrete materials

In this paper a simple, but effective methodology to simulate opening mode fracture in high performance fibre reinforced concrete is presented. The main contribution of the paper is a technique to extrapolate the load displacement curves of three point bending experiments on fibre reinforced concrete. The extrapolation allows the full work of fracture to be determined, from which the fracture energy may be obtained. The fracture energy is used in the definition of a cohesive softening function with crack tip singularity. The softening relation is implemented in an embedded discontinuity method, which is employed for the numerical simulation of three point bending experiments. The experimental work includes a size effect study on three point bending specimens. The numerical simulation provides a satisfactory prediction of the flexural behaviour and the size effect observed in the experiments.     

Investigation of aluminosilicate as a solid oxide fuel cell refractory

Aluminosilicate represents a potential low cost alternative to alumina for solid oxide fuel cell (SOFC) refractory applications. The objectives of this investigation are to study: (1) changes of aluminosilicate chemistry and morphology under SOFC conditions, (2) deposition of aluminosilicate vapors on yttria stabilized zirconia (YSZ) and nickel, and (3) effects of aluminosilicate vapors on SOFC electrochemical performance. Thermal treatment of aluminosilicate under high temperature SOFC conditions is shown to result in increased mullite concentrations at the surface due to diffusion of silicon from the bulk. Water vapor accelerates the rate of surface diffusion resulting in a more uniform distribution of silicon. The high temperature condensation of volatile gases released from aluminosilicate preferentially deposit on YSZ rather than nickel. Silicon vapor deposited on YSZ consists primarily of aluminum rich clusters enclosed in an amorphous siliceous layer. Increased concentrations of silicon are observed in enlarged grain boundaries indicating separation of YSZ grains by insulating glassy phase. The presence of aluminosilicate powder in the hot zone of a fuel line supplying humidified hydrogen to an SOFC anode impeded peak performance and accelerated degradation. Energy dispersive X-ray spectroscopy detected concentrations of silicon at the interface between the electrolyte and anode interlayer above impurity levels.     

Digital piracy intention: a comparison of theoretical models

Digital piracy intention research has yielded different sets of piracy intention determinants based on various theoretical models. In this study, we reviewed the digital piracy literature and empirically compared two theoretical models, which are the models most often used: the theory of planned behaviour (TPB) and the Hunt–Vitell ethical decision model. Data were obtained from university students in South Korea, and structural equation modelling (SEM) was employed to examine and compare the two competing theoretical models in terms of explanatory power, overall model fit and paths' significance. The findings of this study revealed that the TPB is a more appropriate model for predicting digital piracy than the Hunt–Vitell ethical decision model.     

The impact of sulfur on the performance of a solid oxide fuel cell (SOFC) system operated with hydrocarboneous fuel gas

The impact of thiophene in the fuel gas of a commercial solid oxide fuel cell (SOFC) system is investigated for concentrations up to 400 ppmV. Based on the measured voltage–current curves, an empiric correlation for the estimation of the expectable power output of the investigated SOFC system when operated with sulfur containing fuel gases is derived. An interrelation between the open circuit voltage (OCV) and the sulfur concentration of the investigated hydrocarboneous fuel gas is presented and discussed based on corresponding model simulations. The reduction of the steam reforming (STR) activity of the anode cermet material and of the catalytic partial oxidation catalyst used for the fuel gas processing in the investigated SOFC system are found important factors regarding the power output reduction induced by sulfur traces in the fuel gas of SOFCs.     

Effect of microstructure on the electrochemical performance of Ni-ScSZ anodes

The effects of NiO powder morphology and sintering temperature on the microstructure and the electrochemical performance of Nickel-scandia-stabilized zirconia (Ni-ScSZ) cermet anodes for solid oxide fuel cells (SOFCs) were investigated. The particle size and agglomeration of the starting powders were found to affect both the microstructure and electrochemical performance of the Ni-ScSZ cermet anodes. The lowest polarization resistance, 0.690 Ω cm² at 700 °C, was measured for the Ni-ScSZ anode prepared with fine NiO powder (~0.5 µm grain size). This was attributed to the increase in the number of reaction sites afforded by the small grains and well-dispersed Ni and ScSZ phases. The effect of the anode sintering temperature was also found to affect the anode microstructure, adhesion with the electrolyte, and consequently anode polarization resistance. The lowest polarization resistance was observed for the anode sintered at 1400 °C and this was 3–5 times lower than the corresponding values for anodes sintered at lower temperatures.