In-situ intercalation polymerization synthesis and electromagnetic wave absorption property of graphene/PANI/CuO ternary composites

Based on in-situ intercalation polymerization of PANI, graphene/PANI/CuO ternary nanocomposites were synthesized by hydrothermal reaction at 160 °C followed by heat treatment at 280 °C. The morphology and electromagnetic wave absorption property of as-prepared products were investigated. Result shows that the physical exfoliation of graphite into graphene takes place mainly in the hydrothermal process. After hydrothermal reaction for 4 h, prolongation of the reaction time has no obvious effect on graphene exfoliation and the electromagnetic wave absorption of graphene/PANI/CuO. The synthesized graphene/PANI/CuO ternary nanocomposite is a promising candidate for electromagnetic wave absorbing. Double-layer absorbers using graphene/PANI/CuO as absorbing layer present excellent performances. Both effective absorption bandwidths of DB-1 and DB-2 exceed 10.0 GHz when the total thickness is only 3.0 mm. The maximum reflection loss for DB-1 is up to 39.4 dB at 16.1 GHz and that for DB-2 is???47.3 dB at 11.0 GHz.

     

近β马氏体钛合金中的β→ω相变

近β马氏体钛合金的典型热处理制度为固溶时效,该类钛合金在水冷条件下会发生β→ω相变,该相变属于无扩散型相变,相变的形核源于母相(111)晶面的弹性位移重组,而后续时效过程是扩散型相变,其中强化相α相的析出与ω相的体积分数和形貌密切相关。综述了β→ω相变的相变机理和几种典型近β马氏体钛合金中的β→ω相变特点,总结了水冷态近β马氏体钛合金的电子衍射花样的规律。     

掺洗油的萘系高效减水剂的合成工艺优化及性能研究

以洗油、工业萘为原料,设计并合成了一种萘系高效减水剂。采用单因素法与正交法对合成工艺参数进行调整优化,并通过水泥净浆和混凝土试验检测了所合成萘系高效减水剂与水泥的适应性及减水增强性能。结果表明:掺洗油的萘系高效减水剂的磺化温度和缩合时间与未掺洗油的相当,但前者的磺化时间要适当延长,硫酸用量要适当增加,甲醛用量要适当减小;在合成工艺参数优化调整的基础上,洗油可取代25%～30%的工业萘,而萘系高效减水剂性能基本不变,但成本得以大幅度降低。     

FeCrAl纤维混合毡的吸声性能

通过分散机将3种不同丝径的FeCrAl纤维均匀分散后,由铺毡机铺制出混合毡,将该单层混合毡制成一定厚度的多孔纤维吸声材料。测定结果表明,不同材质、同一丝径的两种纤维多孔材料,具有相似的吸声性能;利用混合毡所制成的纤维多孔材料具有与其它纤维多孔材料一样的吸声性能变化规律;无论怎么样改变单层材料的内部结构,其吸声性能均差于正梯度结构的吸声性能。     

FeAl系合金抗高温氧化性能研究进展

FeAl金属间化合物具有优异的力学性能和抗高温氧化、硫化腐蚀性能,被公认为是高温结构材料、高温气体除尘领域内具有重要应用价值的新材料,因而成了人们研究的重点课题之一。系统地讨论了铁铝金属间化合物的氧化过程、机理以及研究的进展情况。     

Overview of the recent performance of DI-BSCCO wire

Sumitomo Electric has been developing the silver-sheathed Bi2223 multi-filamentary wires since the discovery of Bi-based superconductors. DI-BSCCO (Dynamically-Innovative BSCCO) is the high performance wires produced with the controlled-overpressure (CT-OP) sintering technique. The recent R&D activities have enabled to produce the 1000 m-long wires with I_c of 200 A and the maximum I_c reached 250 A at 77 K by short sample. Besides, the fine control of the carrier density with the non-stoichiometric oxygen enhanced the in-field I_c performances at lower temperature. At a magnetic field of 3 T applied normal to wire surface, the I_c of 280 A at 30 K, and 420 A at 20 K were successfully achieved. To meet the growing needs for various high temperature superconducting applications, Type HT wire with high mechanical strength and Type G wire with low thermal conductivity have been developed.     

显微组织三维重构技术在材料科学研究领域中的应用

材料显微组织三维重构与定量表征是材料科学与工程领域的焦点与核心之一。该方法可将材料的内部结构信息及其与性能之间的关系直观地呈现出来,对全面认识材料微观结构并建立材料组织与性能之间的定量关系具有重要作用。总结了国内外关于显微组织三维重构技术在材料研究领域中的应用,并阐述了各种方法,分析比较了各自的优缺点,寻求高精度材料微观组织三维重构方法,有利于促进材料微观组织形态由二维定性表征向三维定量表征的过渡。     

锰氧化物稳定氧化锆的研究现状

综述了过渡金属锰氧化物作为稳定剂制备稳定氧化锆的研究现状及其物理性能,简单介绍了过渡金属Mn掺杂氧化锆基固溶体的基本特性,如Mn在ZrO2中的溶解度、价态变化及其对氧化锆晶格常数的影响,以及其催化性、导电性、磁性能、应用,并展望了今后的研究方向。     

Preparation and performance of MAX phase Ti3AlC2 by in-situ reaction of Ti-Al-C system

In order to clarify the effects of the proportion of raw powders, heating temperature and holding time on the purity and properties of MAX phase Ti₃AlC₂, powder mixtures of Ti, Al and C powder with different ratio were prepared by planetary ball mill and heated under different conditions by spark plasma sintering. The microstructures and phase structures of the as-synthesized samples were characterized, the correlation between the mechanical properties and microstructure and fracture mechanism were investigated systematically. The results show that with the proportion of raw powders Ti:Al:C = 3:1.2:2, the sample heated at 1300 °C for 60 min has the highest purity 97.23 wt% of MAX phase. It has a compact and uniform lath-like structure with the length-thickness ratios of 3–5 and excellent comprehensive mechanical properties: the Vickers hardness, bending strength and fracture toughness are 5.26 GPa, 500 MPa and 7.35 MPa∙m^1/2, respectively. The experimental results show that among the three factors, the proportion of raw powders has the greatest influence on purity of Ti₃AlC₂ phase, followed by heating temperature and holding time. The fracture morphologies of the tested samples demonstrate that under the action of external force, extrusion and kink occurred in the layered structures of Ti₃AlC₂ phase. These two forms of energy dissipation lead to the bending strength and fracture toughness of Ti₃AlC₂ are higher than that of traditional ceramics.     

热处理对Ti90钛合金显微组织及性能的影响

对比研究了退火温度、冷却速度及多重退火对一种新型近α钛合金Ti90显微组织、室温拉伸性能和腐蚀行为的影响.结果表明:在两相区退火时,随退火温度升高,变形组织逐渐球化,初生α相(αp)体积分数降低,次生α相(αs)增多并发生粗化,合金强度逐渐降低,塑性提高;β单相区退火后空冷,组织中原始β晶粒粗大,且有晶界α相析出(αG...