钯－银合金膜分离氢气的研究

采用厚为５０μｍ的Ｐｄ／Ａｇ（２３）合金膜进行了氢气渗透系数的测定和Ｈ＿２／Ｎ＿２混和气分离的研究，得出温度、压力、膜厚、进料气流量、膜的预处理和再活化及膜表面中毒等因素对氢气渗透的影响。分离Ｈ＿２／Ｎ＿２混和气可获得高纯氢气。     

纳米管合成研究进展

当今纳米科学技术飞速发展，其中纳米管已构成了纳米材料的一个非常重要的类别。本文介绍近几年来由化学键结合的纳米管以及由分子间力形成的一些纳米或具有中观尺度的管状结构材料的合成研究进展。     

Optimization of uncertain acoustic metamaterial with Helmholtz resonators based on interval model

Uncertainties existing in the acoustic metamaterial may strongly affect its unusual properties. Aiming at this actuality, the interval model is introduced to treat with uncertainties existing in the acoustic metamaterial with Helmholtz resonators. Frequency intervals in which the sound intensity transmission coefficients are certainly less than the required value and the effective bulk moduli are certainly negative are defined as conservative approximations. Frequency intervals in which the sound intensity transmission coefficients may be less than the required value and the effective bulk moduli may be negative are defined as unsafe approximations. The proportion of the conservative approximation and the unsafe approximation is defined as an approximate precision. Based on the quantification of uncertainties of the sound intensity transmission coefficients and the negative effective bulk moduli, an optimization model for the interval acoustic metamaterial with Helmholtz resonators is constructed. Numerical results showed that even suffering from effects of interval parameters, unusual properties of the optimized acoustic metamaterial (such as the bandgap of the sound transmission and the negative effective bulk modulus) could be improved.     

Evaluation research on applicability of rapid iodide migration test

The applicability of the rapid iodide migration test was systematically studied. Comparative experimental tests of different test conditions, including several external voltages, test durations, concrete ages and mixing proportions, were carried out to make clear the transport behaviors of iodide under parallel electric fields. Numerical simulations were also done using the finite element method to found the correlation between chloride and iodide transport behaviors. The test and numerical results show that the chloride transport behaviors of RIM and RCM tests have a good correlation under the several conditions used in the present paper. Moreover, the influence of external conditions （external voltages, test durations） on the test results is small. Thus, it can be concluded that the RIM method is available to determine the chloride penetration resistance of the chloride-eroded structural concrete.     

Electrochemical investigation of La0.4Sr0.6TiO3 synthesized in air for SOFC application

Journal of Applied Electrochemistry - La-doped titanate materials have been widely investigated as alternative Ni-free anodes for solid oxide fuel cells (SOFCs). In this study, La0.4Sr0.6TiO3 (LST)...     

Size and pressure effects on solid transition temperatures of ZrO2

Transition temperatures between tetragonal and monoclinic polymorphs of ZrO₂ nanoparticles, thin films and nanostructured materials are calculated by considering energetic contributions of surface (interface) energy and surface stress on total Gibbs free energy. The transition temperatures drop as the size of the nanocrystals decreases, which is consistent with available results.     

耐候钢连铸工艺的改进

分析耐候钢连铸出现的问题,认为凝固时应力过大和磷铜元素偏析造成晶界脆化是出现铸坯纵裂的主要原因;结晶器中喂稀土丝恶化保护渣性能,影响结晶器与坯壳间的润滑与传热,并使热流不均匀是连铸漏钢的主因。采用钙处理代喂稀土丝工艺,以及减缓连铸一、二次冷却强度,改进保护渣后,连铸缺陷获得极大改善。     

保温条件下过共晶Al-Si合金半固态浆料的组织演变

研究了保温时间和保温温度对电磁搅拌ZL117合金半固态浆料稳定性的影响.试验结果表明：半固态浆料中初生Si的颗粒直径随着保温时间的延长而逐渐增大,但在前15 min内增长速度比较缓慢,15 min后增长较快;随着保温温度的升高而缓慢增大;初生Si的形状系数随着保温时间的延长而变得越来越大,但也在前15 min内变化较为缓慢,15 min后变大速度突然加快;初生Si的形状系数在620 ℃下保温时最小,在610～620 ℃之间随着保温温度的升高而缓慢变小;在620～650 ℃之间随着保温温度的升高而逐渐增加.     

TENSILE FRACURE IN AN Al-Li ALLOY 8090

ＴＥＮＳＩＬＥＦＲＡＣＵＲＥＩＮＡＮＡｌ－ＬｉＡＬＬＯＹ８０９０￥Ｊｉａｎｇ，Ｄａｍｉｎｇ；Ｗａｎｇ，Ｙｉｎｏｎｇ；Ｈｏｎｇ，Ｂａｎｄｅ；Ｌｅｉ，Ｔｉｎｇｑｕａｎ（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈａｒｂｉｎ１５００８０）Ｓｕ...     

国外小电流空气等离子弧切割技术的发展

本文就小电流空气等离子弧切割工艺的特性、切割质量、切割设备、存在问题和应用情况作了综合介绍。当工作气体含氧量为20％时,切割速度急剧增加,大大优于气割。