大塑性变形对Ag/SnO2材料显微组织与性能的影响

对两种制备工艺制备的SnO2质量分数为5%的Ag/SnO2复合材料进行了不同应变程度的挤压,研究了组织形貌,发现对于反应合成制备的Ag/SnO2材料经过较大真实应变挤压后纤维状组织消失,SnO2颗粒更加弥散.比较了两种方法制备的Ag/SnO2材料的电导率、抗拉强度及延伸率,及质量分数对其的性能的影响.发现经过较大的真实应变挤压,3种性能都得到了很好改善.     

Cell behaviors on surface of pure tantalum with nano-dimpled structure

Tantalum exhibits excellent biocompatibility and good chemical stability, which has been employed in dental and orthopedic applications.The local microenvironment of the surface of implants influence determines the surrounding cell responses.In this work, nano-dimpled structure on the surface of pure tantalum was fabricated by electrochemical anodization.The surface morphology of the nano-dimpled structure was observed, and the dimensions of the nano-dimpled structure were measured by scanning electron microscopy(SEM).The surface roughness of the sample with nano-dimpled structure was measured by atomic force microscopy(AFM).The results show that the diameter of nano-dimpled ranges from 40 to 180 nm, and the higher the applied voltage, the larger the diameter.Moreover, nano-dimpled structure has good hydrophilicity.In vitro results show that nano-dimpled structure can promote the adhesion and proliferation of mouse cranial anterior bone(MC-3T3-E1) cells.The filopodia of MC-3T3-E1 cells can be fully extended on this nano-dimpled structure.On the surface of the nano-dimpled structure with a dimple size of 40 nm, the cells have the longest aspect ratio.The small dimple size of the nanodimpled structure is beneficial to cell proliferation and osteogenic differentiation.     

A paradoxical flame-retardant effect of nitrates in ATH-filled ethylene–vinyl acetate copolymer

In the course of a study of metal salts as flame retardants, it was surprisingly found that metal nitrates reduced the flammability of ATH-filled ethylene–vinyl acetate copolymer (EVA). The limiting oxygen index (LOI) of ATH-filled EVA was increased by the nitrates in the order of Cu(NO₃)₂·3H₂O > (NH₄)₂Ce(NO₃)₆ > Zn(NO₃)₂·6H₂O > Fe(NO₃)₃·9H₂O > Al(NO₃)₃·9H₂O > NaNO₃. The effects were not caused by the water of hydration. All metal nitrates except NaNO₃ reached a UL 94 V-2 rating at 3 phr. Based on TGA, DSC, FTIR, and gas detection, the proposed mechanism of the flame-retardant effect of nitrates is the oxidative degradation of the polymer to produce noncombustible products (CO₂ and nitrogen oxides) at a rate sufficient to interfere with the normal combustion process despite the exothermicity of the oxidative degradation. It is possible that surface carboxylic acid structures also contribute to the flame-retardant effect. © 1995 John Wiley & Sons, Inc.     

金属凝固微观组织形成的数值模拟

依据金属凝固的基本理论,在Oldfield的连续形核和晶粒长大模型基础上,引入了时间因子,运用随机方法,建立了连续冷却条件下形核和生长的随机模型,使形核和生长模型函数与时间直接相关,反映了连续冷却条件下的金属凝固微观组织的演化过程。基于上述模型,编制了计算模拟程序,模拟了Zn-5Al共晶合金微观组织的凝固过程,并用试验结果对模拟结果进行了验证对比,模拟结果与试验结果基本相符。     

低成本钛合金制备技术研究进展

为了降低钛合金的生产成本,美、俄、日、中等国家都在此领域进行了广泛的研究。对国际上新出现的以降低钛合金生产成本为目的的新冶金方法、新的低成本合金化钛合金和新的加工生产技术进行了综述。目前,国际上研究较为活跃的低成本钛冶炼新方法有FFC剑桥法、Armstrong工艺、EMR复合阳极工艺、SRI工艺、Idaho钛工艺及OS工艺。其中,以FFC剑桥法为代表的TiO2直接电解还原方法,最有希望成为替代传统Kroll工艺的新方法。     

金属半固态成形工艺概述

分析了非枝晶半固态金属的特性和半固态金属的成形特征，在此基础上，较详细介绍了金属半固态成形工艺，包括触变成形和流变成形技术。同时，分析了各种成形工艺的优、缺点以及应用范围。     

锆管的焊接

锆是一种稀贵金属,具有良好的耐腐蚀性能,在化工项目中应用前景广阔。文中主要从锆材的特性、加工、清理,焊丝选用、保护气纯度、坡口角度、保护措施等方面对其进行了分析论述,通过大量的焊接试验,研制出一套可用于锆管焊接的工艺措施及保护装置。试验结果表明,对于锆这种极易在高温下氧化、氮化的有色金属,必须采取严格的保护措施、高质量的清理以及较小的热输入量。焊接时尤其要注意电弧两侧的受热区不被氧化。锆管的焊接成功,为日后的焊接技术培训、管道施工提供了技术保障。     

LiBH4／Mg复合氢化物的储氢性能研究

通过球磨LiBHdMg，使得镁的吸放氢性能得到明显改善。活化结果显示，在氩气气氛下，球磨1h的LiBHdMg混合物经250℃，60min处理后的吸氢量可以达到6．7％（质量分数，下同）。200℃，80min处理后的吸氢量可以达到3．0％。而纯镁粉在相同条件下几乎不吸氢。PCT结果显示，LiBH4也明显改善镁氢化后的放氢性能。     

Evolution of {001 } （110） orientation and related lattice rotation of A1 alloy 6111 during rolling

The texture evolution and lattice rotation in A1 alloy 6111 with an initial {001} （110）component during symmetrical and asymmetrical roiling were investigated by means of orientation distribution function（ODF）. The results show that the as-rolled initial {001 } （110） orientation evolves into not only the copper orientation but also all the other orientations along the β fiber, including the brass orientation, by lattice rotation around special directions. Compared with the symmetrical rolling, the {001 } （110）component in the surface layer on the slower roller side evolves more quickly into the orientations along the β fiber during asymmetrical rolling, while that in the surface layer on the faster roller side evolves more slowly.     

Oxide-Scale Evolution on a New Ni–Fe-Based Superalloy at High Temperature

Oxidation of Metals - The isothermal oxidation behavior and oxide-scale evolution on a newly developed Ni–Fe-based superalloy were investigated. Three oxidation stages were generally...