外加磁场对AZ31镁合金焊接接头组织性能的影响

在对5mm厚的AZ31镁合金板进行GTAW焊接的过程中，外加纵向交流磁场，研究了磁场对焊接接头的力学性能和显微组织的影响，并探讨了磁场的作用机理。结果表明：外加纵向磁场通过旋转电弧对熔池进行搅拌，不仅可以细化晶粒，使焊接接头的抗拉强度、硬度得到改善，还可以净化熔池中液态镁合金（使杂质球化并弥散分布），此外磁场的引入还可降低镁合金焊接热裂纹的敏感性，抑制热裂纹的产生。     

一种交流阻抗和弱极化相结合的腐蚀速度测量方法

提出了交流阻抗和弱极化技术相结合的腐蚀速度测量的方法,并依此研制了CMB-4510腐蚀速度测量仪.有效地解决了线性极化技术因估算塔菲尔系数所带来的理论误差,进一步消除了因介质电阻IR降的影响产生的测量误差.结果表明,CMB-4510腐蚀速度测量仪测得的几种体系的腐蚀速度、极化电阻以及介质电阻与M398所测得结果相同;测量缓蚀剂的缓蚀效果与挂片失重法的测试结果完全吻合.     

PLC在接触器试验中的应用

本文介绍了对交流接触器按照UL认证标准,采用PLC进行过载耐久试验,提高了试验的可靠性和试验的自动化程度。     

外加磁场对AZ31镁合金焊接接头组织性能的影响

在对5mm厚的AZ31镁合金板进行GTAW焊接的过程中,外加纵向交流磁场,研究了磁场对焊接接头的力学性能和显微组织的影响,并探讨了磁场的作用机理。结果表明:外加纵向磁场通过旋转电弧对熔池进行搅拌,不仅可以细化晶粒,使焊接接头的抗拉强度、硬度得到改善,还可以净化熔池中液态镁合金(使杂质球化并弥散分布),此外磁场的引入还可降低镁合金焊接热裂纹的敏感性,抑制热裂纹的产生。     

Synthesis and electrochemical properties of Th-doped LiMn2O4 powders for lithium-ion batteries

To improve the cycle performance of eco-friendly and cost-effective spinel LiMN2O4 as the Li secondary batteries, the Th-doped LiThxMn1-xO4 spinel powers were synthesized by solid-state method. The starting materials, Li2CO3,MnO2 and Th(NO3)4·4H2O, were mixed uniformly using a traditional ball milling, which resulted in a uniform particle size distribution in the mixed powers. Tests of X-ray diffraction, SEM, impedance spectra and charge-discharge were carried out for LiThxMn1-xO4 cathode materials. Results show that the synthesized LiTh0.01Mn1.99O4 material exhibits standard spinel structure, regular particle morphology and excellent property of charge-discharge for big current. The capacity retention of the material modified by doping Th is more than 85.1% of the first discharge specific capacity of 111.5 mAh·g -1 after 20 cycles at the current rate 1C, while the pristine LiMN2O4 is only 57% of the first discharge specific capacity of 110.2 mAh·g-1 after the same cycles at the same current rate.     

新型中空纤维膜接触器用于乙醇/水体系分离的探索

引言 醇/水体系分离一直是化工生产中的重要环节,高效的醇/水分离技术能够使醇的产量大大提高,满足日益增长的工业生产需求.传统的分离方法如精馏、萃取等已经相当成熟,但是这些方法在工业生产过程中能耗巨大,越来越受到面临能源资源匮乏的当代社会的关注和制约.在此背景下,面向高效、节能的新型膜接触分离器应运而生,如Alan等[1]指出,工业化或半工业化的过程已经包括膜吸收、膜萃取以及渗透蒸馏等多个耦合分离单元[2-6].     

Measurement of AC conductivity and dielectric properties of flexible conductive styrene–butadiene rubber‐carbon black composites

Flexible conductive polymer composites were prepared using styrene–butadiene rubber (SBR) as a matrix and conductive carbon black as filler. The filler loading was varied from 10 to 60 phr. The effect of frequency, filler loading, temperature, and applied pressure on the AC conductivity, permittivity, and loss factor of the composites was studied. The AC conductivity of low and high loaded composites was found to be frequency dependent and independent respectively. The permittivity and the loss factor were continuously decreasing with increasing frequency. The increase in filler loading increased the AC conductivity, dielectric constant, and loss factor of the composites. Increase in temperature imposed increase in conductivity and permittivity of the composites. With increasing applied pressure the properties showed exponential increase. The effect of time under a constant compressive stress was studied and dielectric relaxation times were evaluated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 986–995, 2007     

AC4D铸铝合金气缸盖渗漏故障成因分析

利用扫描电镜和光学显微镜等手段,对发生渗漏的缸盖,进行测试和定量分析,找到了渗漏问题形成的原因,并提出了消除渗漏故障的措施。生产现场实施表明,改进措施有效改善了铸件的冶金质量,缸盖铸件的水油隔层的缺陷明显减少,发生腔内渗漏的几率大幅度下降。     

Using AC field measurement data at an arbitrary liftoff distance to size long surface-breaking cracks in ferrous metals

We propose a model-based inversion method to size long surface-breaking cracks in ferrous metals using alternative current field measurement (ACFM) data at an arbitrary liftoff distance. This method employs conjugate gradients optimization to invert measured surface ACFM signal to crack depth. To alleviate the adverse effect of sensor liftoff uncertainty on crack sizing, we propose a blind de-convolution algorithm for reconstructing respective surface ACFM crack signal. In this algorithm, the partially known filter function associated with the sensor liftoff is estimated from which the surface crack signal can be restored. The validity of the proposed inversion method is demonstrated by comparing the actual and predicted depths of several simulated and machine-made long cracks in mild steel test blocks.     

膜接触器分离气体研究进展

阐述了膜接触器分离气体的基本原理和组件设计,讨论了膜材料、吸收剂和流动方式的选择,列举了一些商业膜接触器。最后对膜接触器分离低浓度CO2气体的研究进行了展望。