聚苯并噁嗪树脂合成及其高性能化改性研究进展

首先介绍了聚苯并噁嗪树脂(PBZ)的性能和应用,概述了合成PBZ树脂的反应机理以及溶液法、熔融法及悬浮法合成PBZ工艺的优缺点,简述了PBZ树脂固化机理和工艺,回顾了PBZ树脂的高性能化改性手段和PBZ纳米复合材料的国内外研究进展,分析了具有不同分子结构、通过不同加工手段以及含有不同纳米填料改性的PBZ树脂性能改善情况。得出了目前针对PBZ树脂改性研究的重点,并对PBZ树脂的研究与应用做出展望。     

Surficial stability analysis of soil slope under seepage based on a novel failure mode

Normally, the edge effects of surficial landslides are not considered in the infinite slope method for surficial stability analysis of soil slopes. In this study, the limit stress state and discrimination equation of an infinite slope under saturated seepage flow were analyzed based on the Mohr-Coulomb strength criterion. Therefore, a novel failure mode involving three sliding zones (upper tension zone, middle shear sliding zone, and lower compression zone) was proposed. Accordingly, based on the limit equilibrium analysis, a semi-analytical framework considering the edge effect for the surficial stability of a soil slope under downslope seepage was established. Subsequently, the new failure mode was verified via a numerical finite element analysis based on the reduced strength theory with ABAQUS and some simplified methods using SLIDE software. The results obtained by the new failure mode agree well with those obtained by the numerical analysis and traditional simplified methods, and can be efficiently used to assess the surficial stability of soil slopes under rainwater seepage. Finally, an evaluation of the infinite slope method was performed using the semi-analytical method proposed in this study. The results show that the infinite slope tends to be conservative because the edge effect is neglected, particularly when the ratio of surficial slope length to depth is relatively small.     

Preparation of FeNi-based nanoporous amorphous alloy films and their electrocatalytic oxygen evolution properties

The progress of this research is the preparation of FeNi alloy thin films by magnetron sputtering. Each step of the experimental process is based on the electrocatalytic performance of the sample, and characterized by many characterizations means such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray energy spectrometry (EDS) and step gauge thickness test for morphology, structure and elemental composition, etc. The analysis of the characterization results is used as a support for the experimental process. Adjustment of various preparation process parameters for material growth and subsequent processing include doping of non-metallic elements and construction of nanostructures. Doping of C elements can make FeNi based alloy films further amorphous. Zn element is used as a pore-forming agent. The two processes of doping and high-temperature vacuum dealloying can make the film obtain a nanoporous structure, which greatly increases the specific surface area. These two strategies reduce the overpotential (η10) of oxygen evolution reaction (OER) of FeNi alloy thin films to 393 mV and 314 mV, which are reduced by 47 mV and 79 mV step by step. The electrochemical properties of the finally obtained alloy film are: overpotential of 314 mV, Tafel slope of 61.8 mV/dec and the stability of only 10% decay at a current density of 10 mA/cm2 for 12 h. In this study, low-cost transition metals were used as the main materials to design OER catalysts, and the catalytic efficiency was comparable to that of commercial noble metal catalysts. The physical preparation methods made each sample have good reproducibility. It provides the experimental basis and theoretical basis for the design and synthesis of new catalytic materials at a higher level.     

A high temperature X-ray diffraction study of the influence of MWCNTs on the thermal expansion of MWCNT/Ni composites

The inclusion of multiwall carbon nanotubes (MWCNTs) into metallic matrices is expected to improve their electrical and mechanical performance. This work analyses the lattice thermal expansion behavior of MWCNT-reinforced Ni composites in order to understand the influence of CNTs on their thermomechanical properties. The lattice thermal expansion coefficient (CTE) of the composites was estimated from X-ray diffraction measurements as a function of the temperature. The MWCNT-reinforced composites show higher lattice CTE (up to 12%) compared to pure Ni. This behavior is mainly produced by the expansion mismatch between the matrix and the reinforcements. We suggest three main mechanisms that explain the behavior of the CTE of metallic matrices in presence of MWCNT. These mechanisms correlate to the anchoring effect observed in previous macroscopic measurements of thermal expansion carried out on the same system.     

MoO3掺杂Ba0.98Bi0.02(Ti0.9Zr0.1)O3陶瓷的介电性能研究

采用固相反应法制备了Ba<,0.98>Bi<,0.02>(Ti<,0.9>Zr<,0.1>)<,1-x>Mo<,x>O<,3>(x=0,0.01,0.03,0.05)陶瓷,研究了MoO<,3>掺杂对Ba<,0.98>Bi<,0.02>(Ti<,0.9>Zr<,0.1>)O<,3>陶瓷的相结构、表面形貌和介电性能的影响....     

Synergetic improvement strategy on thermoelectric performance of CuAlO2 compacts

We fabricated Sr and Ca-doped CuAlO₂ compacts from the mixed powder of CuO, Cu₂O, Al₂O₃, and SrO or CaO by multi-pass hot pressing followed by spark plasma sintering (SPS). The XRD results showed the reaction of CuO, Cu₂O and Al₂O₃ was rather complete and only CuAlO₂ single phase was formed when the additive amount of SrO or CaO was appropriate. Multi-pass hot pressing increased the relative density and the usage of plate-like Al₂O₃ as reaction raw material enhanced the orientation degree. In spite of performance improvement conflicts through elemental doping, density increase and orientation improvement, the measurement on the thermoelectric performance indicated that the electrical resistivity, Seebeck coefficient, power factor, dimensionless figure of merit (ZT) were improved to varying degrees through the synergetic action of elemental doping, density increase, and orientation control. The highest power factor and ZT of the Ca-doped CuAlO₂ compacts reached 1.54?×?10^?4 W?m^?1 K^?2 and 0.015 at 973?K, respectively. The thermoelectric performance was higher than those of CuAlO₂ at the same temperature in published work before.     

高密度聚乙烯／蒙脱土纳米复合材料的制备与性能研究

采用马来酸酐接枝乙烯醋酸乙烯酯（EVA-g-MAH）和马来酸酐接枝低密度聚乙烯（PE-LD-g-MAH）为相容剂，制备了高密度聚乙烯傣脱土（PE-HD／MMT）纳米复合材料。用X射线衍射和扫描电镜对有机蒙脱土和PE-HD／MMT复合材料的结构进行了表征，研究了蒙脱土和相容剂含量对制备的纳米复合材料力学性能及热性能的影响。结果表明，相容剂的加入有利于插层。MMT在复合材料中呈纳米级分散。其层间距可由2．10nm增大至3．85nm。MMT含量为3％（质量分数，下同）、EVA-g-MAH含量为15％时，复合材料的综合力学性能最好，冲击强度和拉伸强度分别较PE-HD提高43．7％和5.8％。     

Ba1-xBix(Ti0.9Zr0.1)O3陶瓷的介电弛豫特征

采用固相反应法制备了Ba1-xBix(Ti0.9Zr0.1)O3(x=0.01,0.02,0.03,0.04)陶瓷,X射线衍射分析表明所有样品均是四方晶体结构,3%mol的Bi3+能够完全溶入钙钛矿晶格中.不同频率下Ba1-xBix(Ti0.9Zr0.1)O3陶瓷的介电温谱显示所有样品均表现出弥散相变的特征,在x≥0....