氧化锰纳米颗粒的低温水热合成及其电化学性能

基于高锰酸钾和葡萄糖之间的氧化还原反应,采用低温水热法合成了氧化锰纳米颗粒材料.应用X-射线衍射、扫描电镜和氮气吸脱附技术对所得材料的结构、形貌和表面性质进行表征.结果表明,所得材料为低结晶性Birnessite型层状氧化锰,比表面积为129 m2/g.电化学测试结果显示,氧化锰纳米颗粒负极材料具有较高的比容量、较好的循环性能和倍率性能.在100 mA/g的电流密度下,首次放电比容量为635 mAh/g.恒流充放电130次后,容量保持率为65.4％.     

PZT components derived from polysulphone spinning process

The present paper deals with the development of lead zirconate titanate (PZT) fibres, pearls and fibre fragments, for their use as active phase in piezocomposites. As new a approach, the green ceramic components are shaped by polysulphone spinning, allowing for effective and flexible forming over a wide range of different geometries and sizes. The correlation between processing parameters, e.g. the slurry composition, nozzle size and operation velocity, and the resultant shape of ceramic components is analysed. Sintered piezoceramic parts show a dense microstructure. Performance data are evaluated on PZT/epoxy composites. Measurement results of strain, polarisation and piezoelectric coupling are given and discussed. The developed PZT components are seen as key for the creation of smart and lightweight structural components. Further, free formed PZT components open new design approaches for sensing and actuating devices and ultrasound transducers.     

水合物形成促进剂研究进展

添加促进剂是高效制备水合物的研究热点,促进剂及其添加量对水合物生成效果至关重要。本文主要从热力学促进剂和动力学促进剂两大类型进行分析：总结了可溶水相热力学促进剂和不可溶水相热力学促进剂的浓度对水合物形成相平衡的影响;从表面活性剂、纳米粒子和相变材料等添加剂,阐述了动力学促进剂添加量对水合物生成诱导时间、储气量和生成速率等方面的影响。促进剂都存在最佳浓度的添加量,并且不同类型促进剂复配更有利于水合物生成。目前添加促进剂后水合物形成机理的研究大多从宏观现象推测,部分学者通过拉曼光谱、X射线衍射和显微观察探索分析促进剂对水合物形成的微观影响,这方面研究有待于进一步开展。添加量作为水合物形成促进剂的重要指标,研究者应得到水合物形成促进剂的最佳浓度与所研究对象的关联性。     

Facile high yield synthesis of MgCo2O4 and investigation of its role as anode material for lithium ion batteries

In this article, we have reported a one-step scalable synthesis of MgCo₂O₄ nanostructures as efficient anode material for Li-ion batteries and investigated the role of post-synthesis calcination temperature (400, 600 and 800 °C) on its physiochemical properties and electrochemical performances. The XRD pattern of the calcinated sample at 400 °C (MC 400) indicates a pure phase of MgCo₂O₄. However, on increasing the calcination temperature to 600 °C (MC 600), an additional phase corresponding to MgO was detected and the corresponding XRD peak intensity further increased on increasing the calcination temperature to 800 °C (MC 800 °C). This was accompanied by a morphological transformation from flake and rod-like nanostructures, to an agglomerated dense flake-like morphology. Electrochemical studies revealed that the calcination temperature plays an important role in determining the electrochemical performance of the MgCo₂O₄ as anode material. In a half cell, the MC 600 showed the best electrochemical performance with high discharge capacity of 980 mA h g⁻¹ (2nd discharge at 60 mA g⁻¹) and a reversible discharge capacity of 886 mA h g⁻¹ at the end of 50 cycles with high coulombic efficiency of 98%. Long term stability was carried out at 0.5C which showed a capacity retention of 358 mA h g⁻¹ at the end of 500 cycles. The superior electrochemical performance of the MC600 can be attributed to the presence of the small amount of MgO, which is believed to provide the anode materials better structural stability during cycling. The claim was further supported by ex-situ TEM analysis of the anode material of a cycled cell (50 cycles).     

Development of waste derived nano-lakargiite bonded high alumina refractory castable for high temperature applications

This work provides a new binder system, i.e., nano-lakargiite (NL) [CaZrO₃] for unshaped refractories. NL powder formulation is done through a green and facile route, i.e., solution mixing technique, which is easily capable of recycling the byproducts. The waste eggshells are practiced as a source of CaO for the preparation of NL. The characteristics such as differential thermal/thermogravimetric (DTA-TGA) analysis, X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) of the synthesized NL powder are accomplished. The single phase orthorhombic crystal structure with the Pnma space group of nano CaZrO₃ (avg. crystallite size ∼19 nm) is attained at 1100 °C. High alumina castable specimens are formulated through the replacement of calcium aluminate cement (CAC) by the NL and heat treated at 1600 °C. The different physico-mechanical properties of the prepared castables are comprehensively investigated. The corrosion resistance in the molten glass at 1400 °C is also examined. The properties are also equated with the different advanced bonding systems of high alumina refractory castables. Significant progress in terms of densification, hot strength, and thermal shock resistance is achieved for the NL bonded refractory castables.     

Iron oxide colouring of highly-translucent 3Y-TZP ceramics for dental restorations

The influence of 0.01–2 mol% Fe₂O₃ powder addition on the microstructure, mechanical and optical properties, and hydrothermal stability of highly-translucent 3Y-TZP ceramics is assessed and compared with commercially available co-precipitated 0.18 mol% Fe₂O₃ doped ZrO₂ powder-based ceramics. Only those ceramics with up to 0.1 mol% Fe₂O₃ resulted in a proper shade for dental zirconia ceramics, with a typical composition of 87 vol% t-ZrO₂ and 13 vol% c-ZrO₂. The amount of cubic phase increased at higher Fe₂O₃ content. The hardness (∼13 GPa) and fracture toughness (∼3.6 MPa m^1/2) of the 0.01 mol% - 0.1 mol% Fe₂O₃ doped 3Y-TZP was comparable, whereas the hardness decreased above 0.5 mol% Fe₂O₃ and the fracture toughness decreased above 2 mol% Fe₂O₃. The hydrothermal ageing resistance slightly increased for Fe₂O₃ concentrations up to 1 mol%, whereas the translucency slightly decreased with increasing Fe₂O₃ content.     

Microwave drying of CuCl residue from hydrometallurgical zinc recovery process

CuCl residue is a hazardous waste from the hydrometallurgical zinc recovery plant. It is very difficult to recycle due to complicated composition, highly corrosive nature, and refractory characteristics. Recently, a new process of microwave drying and roasting was successfully developed to produce both CuO solid and HCl gas products from the CuCl residue. In this paper, the dielectric property of the CuCl residue was measured under different moisture contents. The microwave absorption characteristics of the CuCl residue improved considerably as its moisture content increased. Laboratory-scale drying tests were conducted to evaluate the kinetics of microwave drying and to optimize the operation parameters. The efficiency of microwave drying was further demonstrated in industrial-scale level by microwave dryer developed in in-house. Finally, the drying mechanism of microwave heating of the sticky material was discussed and several measurements were optimized/implemented to intensify the drying process.     

二氧化硅核壳纳米材料的研究进展

核壳型纳米材料作为一种新型的复合型材料,在内核和外壳的协同作用下,能够发挥出单一材料或合金无法比拟的性能优势。根据组成材料属性的不同可以将核壳纳米材料分为无机/无机、无机/有机、有机/无机和有机/有机核壳材料4大类。介绍了核壳材料的形成机理,主要对以二氧化硅为外壳,以金属、金属氧化物、分子筛为内核的几种无机核壳材料的最新研究成果及应用进行了综述。最后,对核壳材料未来的发展前景进行了展望。     

Assessing the Antimicrobial Activity of Polyisoprene Based Surfaces

There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred.     

尼龙6纺织梭专用料及其应用

介绍尼龙６纺织梭专用料的配方、工艺、性能及加工和应用。实践表明专用料配方合理、工艺可行性能优良、以其注射成型的纺织梭性能可靠、生产效率高、使用寿命长、附加值高、完全可替代压缩水生产纺织梭，具有工业推广应用价值。