A concept of reactive compatibilizer‐tracer for studying reactive polymer blending processes

A concept called reactive compatibilizer‐tracer is proposed. The latter bears reactive groups capable of reacting with its counterpart on forming a copolymer for in situ compatibilization, and fluorescent labels allowing determining very small amounts of the in situ formed compatibilizer and formation of micelles when it occurs. Owing to this concept, it is shown that a reactive compatibilizer may be very efficient at the beginning of a reactive blending process and may suddenly become completely inefficient, resulting in an abrupt and drastic increase in size of the dispersed phase domains. © 2015 American Institute of Chemical Engineers AIChE J, 62: 359–366, 2016     

Fabrication and electromagnetic interference shielding effectiveness of Ti3Si(Al)C2 modified Al2O3/SiC composites

A dense alumina fiber reinforced silicon carbide matrix composites (Al₂O₃/SiC) modified with Ti₃Si(Al)C₂ were prepared by a joint process of chemical vapor infiltration, slurry infiltration and reactive melt infiltration. The conductive Ti₃Si(Al)C₂ phase introduced into the matrix modified the microstructure of Al₂O₃/SiC. The refined microstructure was composed of conductive phase, semiconductive phase and insulating phase, which led to admirable electromagnetic shielding properties. Electromagnetic interference shielding effectiveness (EMI SE) of Al₂O₃/SiC and Ti₃Si(Al)C₂ modified Al₂O₃/SiC were investigated over the frequency range of 8.2–12.4 GHz. The EMI SE of Al₂O₃/SiC-Ti₃Si(Al)C₂ exhibited a significant increase from 27.6 to 42.1 dB compared with that of Al₂O₃/SiC. The reflection and absorption shielding effectiveness increased simultaneously with the increase of the electrical conductivity.     

纳米铝/氧化铜复合材料的制备及热性能

以聚乙二醇(PEG)为模板制备了纳米氧化铜。以一种高分子材料为包覆材料自组装制备了纳米铝/氧化铜(Al/CuO)复合材料。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱仪(EDS)、X射线衍射(XRD)等对材料的结构形貌进行了表征。利用热重分析法(TG)和差示扫描量热法(DSC)对比研究了自组装法(含包覆材料)与超声共混法(不含包覆材料)制得样品的热性能。研究了不同Al与CuO摩尔比下Al/CuO复合材料的放热量。结果表明,纳米铝与CuO发生铝热反应的放热峰约为576.4℃,放热量达1 093J/g。含有包覆材料的复合材料比不含包覆材料的复合材料具有更大的放热量。在纳米铝与CuO摩尔比为1.0∶1.2时铝热反应放热量最大,可达1 093J/g。     

发展动力配煤 控制空气污染

分析了我国煤炭利用过程中产生空气环境污染问题的主要原因 ,介绍了我国动力配煤的现状和重要意义 ,指出动力配煤是一种经济有效的空气污染控制技术 ,并阐明了该技术的研究发展方向。     

探讨配矿数学模型提高铁精矿品位

运用多元回归务析法，分析铁矿石采出品位、碎矿抛岩品位和铁精矿品位三者之间的相互关系，并以此为依据，确立配矿数学模型，提出配矿方案。     

动力煤配煤技术基础

阐述了我国动力煤利用现状．从煤在不同类型锅炉的燃烧方式出发，讨论了煤质特性对燃烧工况及对环境的影响，以及一些非加和性煤质指标，如可磨性、粒度组成、煤炭熔融性等对动力配煤的影响，进而提出选定动力配煤方案的原则．     

人工神经网络方法在优化动力配煤中的应用研究

对神经网络ＢＰ算法的一些改进作了大量的数值试验研究，并组合了部分改进方法用于动力配煤问题中状态预测过程的建模，最后把神经网络方法纳入到非线性混合离散变量优化设计方法（ＭＤＯＤ法）中，对杭州配煤场 动力配煤过程作了应用介绍。     

Rapid preparation of Bi0.5Na0.5TiO3 ceramics by reactive flash sintering of Bi2O3-NaCO3-TiO2 mixed powders

Lead-free Bi_0.5Na_0.5TiO₃ piezoelectric ceramics were successfully prepared by reactive flash sintering of Bi₂O₃-NaCO₃-TiO₂ mixed powders, where phase transformation and densification occurred simultaneously. The influence of electric field strength, current density and holding time at constant current state on the phase transformation and densification were investigated. The current density had a significant influence on the extent of phase transformation and densification. The holding time had no influence on the phase transformation, but had an important effect on crystallinity of sample. The sintered bulks exhibited the maximum polarization P_m of 16.8 μC/cm², remanent polarization P_r of 9.6 μC/cm², coercive field E_c of 29 kV/cmm, maximum electric-field-induced strain of 0.053 %, and piezoelectric coefficient d₃₃ of 85 pC/N. The reactive flash sintering can prepare the dense and single-phase ceramics from multiphase precursor powders in one step of flash, providing a new way for rapid production of ceramic materials.     

UHTC-based matrix as protection for Cf/C composites: Original manufacturing,microstructural characterisation and oxidation behaviour at temperature above 2000 °C

In space propulsion applications, the development of new ceramic matrix composites with improved resistance to oxidation and ablation at high temperature is needed and ultra-high temperature ceramics-based ones appear the most suitable. Combination of both powder impregnation (ZrB₂, C) and liquid silicon infiltration enabled manufacturing of UHTC based matrices in C_f/C preforms with less than 10 vol% open porosity and various proportions and homogeneous distribution of C, ZrB₂, SiC and Si. Oxidation behaviour was evaluated on composite structures using an oxyacetylene torch at temperatures higher than 2000 °C. Chemical analyses and microstructural observations before and after oxidation testing evidenced the protection ability of ZrB₂-SiC-Si matrices thanks to the formation of multi-oxide scales which resisted even tested durations of 6 min and pointed the unharmful presence of residual 12 vol% silicon on the composite for use at high temperature under high gas flows.     

温度对酚醛树脂/丁腈橡胶复合材料摩擦学性能的影响

采用机械共混法将酚醛树脂（PF）与丁腈橡胶（NBR）进行混合而制得PF/NBR复合材料,研究了PF用量对NBR的拉伸性能、撕裂性能及硬度的影响,使用多功能材料表面性能综合测试仪、三维表面形貌仪和扫描电子显微镜对力学性能最优的PF/NBR复合材料试样A 2（添加5份PF）在不同温度下的摩擦性能进行了探究,并与未添加PF的试样A 0进行了对比,此外还对PF/NBR复合材料的磨损机理进行了初步分析。结果表明,当温度超过75 ℃时,试样A 0的摩擦系数曲线整体呈持续上升的趋势,同时其表面有较多孔洞,分子间结合力下降,耐磨性变差,而试样A 2的摩擦系数则基本保持稳定,磨损行为表明其磨损机理由磨粒磨损逐渐转变为黏着磨损;相对于试样A 0而言,试样A 2在高温下仍能保持较好的摩擦性能。