Structural and electrical characterisation of silica-containing yttria-stabilised zirconia

Zirconia stabilised by yttria has a high oxide ion conductivity at high temperature and, therefore, is currently used as electrolyte in Solid Oxide Fuel Cells. Silica is normally avoided in this material because formation of amorphous silica phases along the grain boundaries causes an increased grain boundary impedance. The present study examines the effect of SiO₂ and SiO₂ with Mn-oxide on the structure and resistivity of yttria stabilised zirconia electrolyte materials. During fabrication of Solid Oxide Fuel Cells, Mn readily diffuses from the manganite-based cathode into the electrolyte. It is shown that a grain boundary phase which causes an insulating layer in the grain boundaries is formed when both SiO₂ and Mn-oxide coexist in the samples, whereas such effects are much less pronounced when only SiO₂ is present.     

电子微连接高温无铅钎料的研究进展

基于环保的压力和人类健康的需求,电子产品微连接材料采用无铅钎料代替传统含铅钎料已是必然趋势。总结了新型无铅高温钎料的基本要求,重点评述了Bi基合金、Au基合金、Zn基合金和Sn-Sb基合金等几类钎料国内外研究现状,指出通过多元合金相图计算、合金化、材料复合化的方式开发成本、工艺性能均能与含铅钎料相媲美的无铅高温钎料。     

Photoelectrochemical cells with n-type ZnSe and n-type Sb2Se3 thin film semiconductor electrodes

Photoelectrochemical cells with thin film semiconductor electrode made of ZnSe or Sb₂Se₃ and a platinized platinum electrode as counter electrode with I⁻/I⁻₃ electrolyte have been investigated. The maximum efficiency has been observed with the cells for light wavelength about 600 nm. The conversion efficiencies of the cells with ZnSe electrode and Sb₂Se₃ electrode were 0.03% and 0.13%, respectively with light intensity of 92 mW cm⁻².     

炮钢表面电弧离子镀TiAlN薄膜的摩擦磨损性能

为了提高PCrNi3Mo钢的耐磨性,利用电弧离子镀技术在其表面沉积了Ti_(0.7)Al_(0.3)N和Ti0.5Al0.5N薄膜,分析了沉积态和磨损态薄膜膜层的微观结构和形貌.结果表明,两种薄膜膜层均属于晶粒细小的柱状晶结构.Ti_(0.7)Al_(0.3)N和Ti0.5Al0.5N薄膜的硬度分别比PCrNi3Mo钢提高了4.75和4.22倍,而弹性模量分别比PCrNi3Mo钢提高了88%和84%.Ti_(0.7)Al_(0.3)N薄膜的稳定摩擦系数较小,两种薄膜具有显著的减摩耐磨作用.PCrNi3Mo钢的磨损机理主要为严重粘着磨损,而两种薄膜的磨损机理属于轻微粘着磨损.Ti0.5Al0.5N薄膜因脆性断裂局部产生了更大面积的剥落区,低硬度的PCrNi3Mo钢基体对膜层的支撑力变小是导致薄膜局部发生开裂破坏的主要原因.     

A comprehensive review of energy management optimization strategies for fuel cell passenger vehicle

With the gradual maturity of fuel cell vehicle technology, it gives a better opportunity for the application of passenger vehicles. In this paper, the energy management optimization strategies of fuel cell passenger vehicle (FCPV) are summarized for the first time. Initially, in this review, the topological configurations of FCPV are classified systematically. The optimization objectives, energy consumption and fuel cell life, are proposed for FCPV. Then the energy management strategies (EMSs) are illustrated and analysed based on the optimization objectives above. In terms of the complex and changeable characteristics of FCPV driving conditions, the latest FCPV EMSs which depend on driving information prediction technologies are discussed and summarized. The purpose of this paper is providing references for the development of new generation FCPV energy management optimization strategies.     

Improved mechanical properties of biomedical ZrNbHf alloy induced by oxidation treatment

The effects of air oxidation upon the kinetics and mechanical properties of ZrNbHf alloy were studied in the temperature range of 550–650 °C. The oxidation kinetics derived from the weight gain measurements showed a parabolic rate law and an oxidation breakdown behavior transforming from a parabolic to linear rate law observed at 650 °C. The microstructure analysis indicates that the oxide layer consists of both monoclinic and tetragonal ZrO₂ and undergoes a transformation between t-ZrO₂ and m-ZrO₂ with increasing oxidation time, which is an important reason for kinetics transition. The mechanical property examination presents that the oxidation treatment brings about a nearly fourfold increase in the surface hardness with a protective thickness limit of 4–6 μm. Most interestingly, the hardened surface oxide layer brings about a nearly 70 MPa increase in yield strength and a slight decrease in tensile elongation under true stress–strain conditions. The present study reports on an optimized oxidation process designed to obtain a protective and hardened ZrO₂ film for biomedical ZrNbHf alloy with higher performance.     

Structure and photoluminescence of polymer-derived Pr-doped SiAlON red phosphor

The praseodymium (Pr)-doped silicon based aluminum oxynitride (SiAlON) red phosphors were prepared by a novel polymer-derived method using polycarbosilane and acetylacetonates as the starting materials. The organic precursors containing Pr and Al were formed via polymer reactions at 320 °C, followed by nitridizing with NH₃ at 800 °C for the organic-inorganic transformation, and finally by sintering under N₂ at 1650 °C for the crystallization. Accordingly, the chemical composition, surface morphology, crystal structure and photoluminescence property of the polymer-derived Pr-doped SiAlON phosphors were studied. The strong red emission was observed at 623 nm under the excitation of 290 nm with the average decay time of 30 μs, corresponding to ¹D₂→³H₄ transition. The empirical formula was determined to be Si_3.0Al_0.2O_0.3N_3.0C_0.03Pr_0.02, which is Si rich with trace amount of C. The main crystal phase was identified as hexagonal β-(Si,Al)₃(O,N)₄:Pr with a space group P6₃. Each Pr ion was located in the lattice along c-axis by coordinating with three nearest N/O atoms in the neighboring plane. In addition, the amorphous Si rich components were also presented. Possible impure phases, accounted for less than 5%, might include SiC, (Pr₂(Al_0.5Si_2.5O_3.5N_3.5) and PrSi₃N₅.     

Fabrication of TiO2 compact layer precursor at various reaction times for dye sensitized solar cells

A compact layer is used to increase the photoelectric conversion efficiency on DSSCs due to it can improve the transparent conduction oxides (TCOs) surface and prevent the electrolyte from directly contacting the ITO (Indium Tin Oxide) substrate. In this study, DSSCs with compact layer reacting for three hours are compared to those without compact layer, where the short-circuit current and solar energy conversion efficiency are improved by 22%, and 26%, respectively. Based on electrochemical impedance spectra (EIS) measurements, we clarify that the compact layer can decrease the charge interfacial resistance and the leakage current due to the fact that the dense TiO₂ nanoparticles can effectively prevent charge transport from the photoanode to the ITO substrate. We compared different reacting times for the formation of the compact layer, and showed that the quantum efficiency of DSSC is higher when a 3 h reacting time is adopted with respect to a 24 h processing time. A study of the various molar ratios of the precursor solution has been done. The data showed that the 1 M is the optimal molar ratio. We also studies the compact layer formation on FTO with respect to ITO, showing that the FTO substrate has higher photoelectric conversion efficiency.     

钛表面纳米管处理后在含白蛋白模拟唾液中的电化学性质(英文)

探讨了白蛋白对表面纳米管处理后的纯钛( nanotubular Ti,NT)中模拟唾液中电化学行为的影响,白蛋白浓度为5 g/L.与机械抛光的纯钛(mechanically polished Ti,MPT)相比,白蛋白导致NT的开路腐蚀电位向正方向偏移,而且更加有效地导致其阳极极化行为的变化与腐蚀电流密度的降低.取决于纳米管层性质的表面电容随着浸泡时间的增加而增大.结果表明,纯钛表面的纳米管有利于白蛋白的吸附.