共查询到20条相似文献,搜索用时 15 毫秒
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Perturbation method analysis of AC-induced corrosion 总被引:1,自引:0,他引:1
Rong Zhang 《Corrosion Science》2008,50(6):1664-1671
A nonlinear model for corrosion of metals subjected to alternating voltage (AV) induced corrosion that includes the elements corresponding to the polarization resistance, the double layer capacitance and the solution resistance is developed. The results show that corrosion of materials under AC conditions is greatly enhanced by the peak potential and by an increase in the ratio of the anodic-to-cathodic Tafel slope. The AC-induced corrosion rate: (i) decreases with the frequency of the applied signal and with an increase in the DC corrosion potential, (ii) is independent of the DC corrosion rate, and (iii) increases with the peak potentials of the AV signal. 相似文献
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AC7A铝镁合金端盖的铸造工艺 总被引:1,自引:0,他引:1
优化了AC7A合金的成分组成,满足了300 km/h动车组牵引电机对材料力学性能的特殊要求.熔炼过程分两阶段进行的方法,有效地控制了Fe、Si两种元素对合金液的污染.合金液在覆盖熔剂保护下进行熔炼和浇注的方法,预防了铸件针孔缺陷的产生.低压铸造工艺引入阶梯式双层浇注系统后,解决了Al-Mg合金易产生夹渣和缩松的问题. 相似文献
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采用挤压铸造生产AC4CH合金铸件,研究了铸造压力、充型速度和充型距离对挤压铸件组织和性能的影响.挤压铸造AC4CH铝合金铸件组织由初生α-Al和共晶硅相组成,随着充型距离的增加,铸件显微组织明显细化.随着铸造压力和充型速度的增大,共晶相含量降低并且分布均匀.铸造压力和充型速度的增大可提高铸件的抗拉强度、屈服强度,但是铸造压力增大到一定程度后强度上升幅度减缓. 相似文献
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利用电化学测试、表面分析及失重分析技术,研究了模拟高铁动态交流干扰下管道钢的腐蚀行为和规律及阴极保护的有效性.结果 表明,动态交流干扰下,阴极保护电位向负方向偏移,交流干扰增大管道的阴极保护电流密度;动态交流干扰下,随干扰水平增加,管道钢腐蚀程度增加,点蚀坑明显加深.阴极保护明显减缓交流干扰试样的腐蚀程度,腐蚀速率降为... 相似文献
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SCR—MOSFET交流方波逆变焊机的研究 总被引:1,自引:0,他引:1
本文介绍了SCR-MOSFET双逆变交流方波弧焊电源的工作原理,探讨了场效应管逆变器的若干问题,诸如逆变器的动态数学分析,场效应管并联均流及峰值电压抑制等问题。 相似文献
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E. Abd El-Wahabb M.M. Abd El-AzizE.R. Sharaf M.A. Afifi 《Journal of Alloys and Compounds》2011,509(34):8595-8600
AC conductivity and dielectric properties have been studied for amorphous thin films with different thicknesses of glassy system GeSexTl0.3 with X = 3, 4 that prepared with thermal evaporation technique. The measurements are taken at temperature range (303-403 K) and frequency range (102-105 Hz).AC conductivity σac(ω) is found to be proportional to ωs where s < 1. The temperature dependence of the ac conductivity and the parameter s can be discussed with the aim of the correlated barrier-hopping (CBH) model.The dielectric constant ?′and the dielectric loss ?″ showed frequency and temperature dependence. The maximum barrier height WM calculated from the dielectric measurements according to Giuntini equation are in good agreement with that proposed by the theory of hopping of charge carriers over a potential barrier as suggested by Elliott in the case of chalcogenide glasses. 相似文献
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介绍用于轧钢机大型同步电机的大功率交-交变频装置的构成和技术参数,着重叙述了该装置的控制和调节系统、矢量控制、传动系统的多种保护设施等方面的详细情况。 相似文献
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交流方波氩弧焊功率变换器 总被引:1,自引:0,他引:1
本文提出一种用于交流氩弧焊的功率变换器,它与具有陡降特性的直流焊接电源配套进行交流方波氩弧焊。文中介绍了其工作原理,性能特点及主要研究设计内容。结果表明,该方法是实现高质量交流氩弧焊的有效途径之一。 相似文献
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论述并分析了交流弧焊机初级串接电容后对焊机空裁状态各性能参数的影响,通过实验证实了理论分析是正确的。对于交流弧焊机的应用有实际的指导意义。 相似文献
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本文介绍了交流接触器节能技术的发展和应用.阐述了各种节能技术的应用和优缺点以及国外节能产品的发展. 相似文献
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介绍了焊机主要参数设计计算的选定方法及主要制造工艺。本焊机体积小、重量轻、携带方便,使用灵活、接插新颖、性能优越,是国内首次采用次级线圈抽头并直接作为换档接头的一种最轻便的交流弧焊机。 相似文献
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《腐蚀工程科学与技术》2013,48(5):322-326
AbstractThe alternating current (AC) has a strong influence on the corrosion of carbon steel Q235 in soil. AC corrosion1–3 was investigated by morphology observation, weight loss analysis and electrochemical measurement. The results of morphology observation and weight loss analysis showed that AC increased the corrosion rate and the influence was weakened when a protective layer was built up. The electrochemical tests confirmed that in the presence of AC, the corrosion potential shifted toward the negative direction and the exchange current density increased.4–9 相似文献