热轧带肋钢筋时效后拉伸性能变化的研究

研究了HRB335钢筋、HRB400钢筋和英标460MPa级钢筋时效后的拉伸性能变化。结果表明,自然时效后屈服强度呈下降趋势,可降低20～30MPa,抗拉强度变化不大,伸长率略有上升;一般钢筋自然时效15～30d后拉伸性趋于稳定,穿水冷却钢筋60～180d后拉伸性能才趋于稳定;可用200℃×1h的人工时效工艺模拟自然时效。这为钢筋的检验和使用提供了有益的参考。     

The melt structures above the liquidus in SiCp/Al composite

The properties and the structures of liquid melt above the liquidus play an important role in determining the resultant properties of the alloy and the composite. In this paper, the melt structures of SiCp/Al composites with two different reinforcement volume fractions were investigated using liquid metal X-ray diffraction and differential scanning calorimetry. The experimental results showed that the melt structures of SiCp/Al composite are different from that of liquid matrix alloy, a Si–Si hump in the pair radial distribution function in SiCp/Al composite melt and the DSC trace indicated that Si is not well distributed above the liquidus, the size change of short-range-order (SRO) in SiCp/Al composite melt indicated the diffusion of Si from chemical reaction between SiC and molten Al is possible only after a given temperature or after some extent concentration fluctuation of Si. The mechanisms for the observed phenomenon are also discussed in this paper.     

The effect of Si upon the interfacial reaction characteristics in SiCp/Al-Si system composites during multiple-remelting

The composite interfaces play an important role in determining the resultant composite properties, especially the development of interfacial reaction during remelting is critical to the commercialization and sustainable-development of metal matrix composites. In this paper, the interfacial reaction characteristics of SiCp/Al-Si system composites during multiple-remelting were investigated by Differential Scanning Calorimeter (DSC). It was found that the interfacial reactions were not sensitive to remelting number, remelting temperature and reinforcement volume fraction after a degree of reaction, and the results also suggested that the preventation effects of Si upon the interfacial reaction SiCp/Al were mainly attributed to the Si released from the interfacial reaction, while the original Si content in the master alloy also has the same effect only after a given Si content.     

二氧化氯在循环冷却水中的应用

本文介绍了ＣｌＯ２作为杀菌灭藻剂的工艺机理,在工业循环水中的杀菌灭藻效果,并对其进行经济性比较。     

抗辐照损伤金属基纳米结构材料界面设计及其响应行为的研究进展

在高能粒子辐照条件下,金属基结构材料内部会出现不同类型的缺陷,这些辐照诱导缺陷的大规模聚集会造成损伤,降低材料的结构稳定性,从而严重影响结构材料的力学和物理性能。通过材料设计的手段引入界面充当缺陷陷阱,可通过对辐照诱导缺陷的分离、吸收和湮灭,有效减轻材料的辐照损伤。纳米结构材料由于含有高密度界面,其辐照损伤行为的研究于近20年快速发展,且界面能被证实是影响界面调控辐照损伤的重要因素。本文聚焦金属基纳米结构材料,围绕界面设计,详细阐述了低能和高能界面设计下,不同结构类型的界面对辐照损伤的影响及界面响应行为的研究进展,为进一步实现界面结构优化,平衡界面能、界面结构稳定性及良好辐照抗性之间的关系提供理论基础和科学依据。最后,基于前述界面设计的思想,总结了近年来发展的碳/金属界面设计及抗辐照损伤的研究进展,展望了未来先进抗辐照金属基纳米结构材料的设计和发展。     

Preparation of copper coated carbon nanotubes by decomposition of Cu(II)acetylacetonate in hydrogen atmosphere

In this paper, copper coated carbon nanotubes (CNTs) was synthesized by decomposition of Cu(II) acetylacetonate (Cu(acac)₂) in hydrogen atmosphere at 300 °C. The thickness of the copper coating was in nanoscale according to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, and Raman spectra indicated that certain intermediate bonds were formed between copper and the template CNTs. The crystalline structure of copper and its growth orientation were determined by X-ray diffraction (XRD) and selected area electron diffraction (SAED). The copper coating on CNTs had a face-centered cubic structure and its growth orientation was parallel to planes. The method developed in this paper had the advantages of simplicity in both process control and experiment equipments, so that it might provide a possibility of large-scale production.     

Surface modification induced shielding effects on electron orbital coupling in metallofullerene

The electronic properties of four metallofullerenol samples (La@C82(OH)32, La@C82(OH)24, La@C82(OH)18, La@C82(OH)12) and La@C82 were investigated by synchrotron radiation photoelectron emission spectra (PES). A new emission peak with binding energy of 13.9 eV, which is attributed to La 5d orbitals coupling with nanocage orbitals, is observed in PES of La@C82 for the first time. This suggestion is also supported by previous DFT calculations. Furthermore, the new emission peak disappears when the surface of La@C82 is modified with specific numbers of OH groups, which means the electron orbital coupling between inner metallic atoms and outer nanocage in metallofullerene could be shielded by surface modifications on the outer nanocage.     

蝶翅结构负载银颗粒表面增强拉曼散射性能

将银粗糙化的蝶翅三维结构引入到表面增强拉曼散射(surface enhanced Raman scattering, SERS)基材中,提高检测效果。采用绿带翠凤蝶蝶翅作为基板,将纳米银金属颗粒负载其上,合成了经有序粗糙化的表面增强拉曼散射基底。采用场发射扫描电镜及透射电镜分析了有序银粗糙化蝶翅SERS基底的形貌特征。并以罗丹明6G作为探针分子,可检测到浓度低至10^-14mol/L的标样溶液,且检测效果好于二维平板SERS基底,经计算得到绿带翠凤蝶SERS基底的增强因子为1.57×10⁷。在试验的基础上,结合三维有限时域差分的计算方法(finite difference time domain, FDTD),模拟计算得到绿带翠凤蝶SERS基底的电场强度E分布,其log|E|²的值为3.85,其对激发光的反射率仅为6%。研究表明银粗糙化的蝶翅三维结构,可以使表面的电场强度有显著增强。     

遗态及其功能复合材料

经过自然界的长期选择和进化,很多生物形成了多维、分级的精细结构,从而辅助其实现一种或数种功能目的。这为新型功能材料的设计和开发提供了很好的借鉴,因此近些年来研究并模仿生物结构,已成为新材料研究的主要热点之一。然而,由于多数生物结构非常精细复杂,因此直接采用传统的人工方法很难制备出类似的结构。遗态方法通过直接以生物结构为模板,选择合适的物理化学方法,在保持模板精细分级结构的同时,将框架成分转化为目标材质,可制备具有生物精细分级结构的新型功能材料。文章从遗态的思路和原理出发,给出了几种常用的制备方法,并介绍了近几年来基于几种典型生物结构的遗态材料研究进展,以及在光响应、光催化、电磁波吸收、气敏等相关领域的功能探索。