共查询到20条相似文献,搜索用时 15 毫秒
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Sukho Seo Gyudong Choi Tae Jhoun Eom Bokwon Lee Soo Yeol Lee 《Metals and Materials International》2017,23(4):756-763
The eddy current responses of Electrical Discharge Machining (EDM) notches and fatigue cracks are directly compared to verify the reliability of eddy current inspection. The fatigue crack growth tests using a constant load range control mode were conducted to obtain a variety of edge crack sizes, ranging from 0.9 to 6.6 mm for Al alloy and from 0.1 to 3 mm for Ti alloy. EDM notch specimens of Al and Ti alloys were accordingly prepared in lengths similar to that of the fatigued specimen. The crack length was determined by optical microscope and scanning electron microscope. The eddy current responses between the EDM and fatigued specimens with varying notch/crack length were examined using probe sensors at (100-500) kHz and (1-2) MHz for Al and Ti alloys, respectively. The results show a significant difference in the eddy current signal between the two specimens, based on the correlation between the eddy current response and notch/crack length. This suggests that eddy current inspection using the EDM reference specimen is inaccurate in determining the precise crack size, unless the eddy current response data base is obtained from a fatigue-cracked specimen. 相似文献
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Analysis of eddy current interaction between a parallel coil and a ferromagnetic pipe with remanence
Eddy current field excited by a parallel coil placed next to a ferromagnetic pipe with remanence is studied in this paper. The influence of the remanence is analyzed at first. The analytical solutions to the ferromagnetic pipe eddy current field are deduced by means of a second-order vector potential formalism, and the analytical expression for the impedance change of the excitation coil is constructed. Theoretical analysis of the influence for the remanence and the analytical solutions to the eddy current field are verified by experiments. 相似文献
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The current distribution of carbon steel beneath intact organic coating exposed to 3.5% NaCl solution was investigated by the wire beam electrode (WBE) method. The electrochemical impedance spectroscopy (EIS) of individual electrodes with high current was characterized to analyze the behavior of the coating degradation and metal corrosion at coating/metal interface. The polarity switch of the electrode under the coating was observed. The mechanism of coating degradation and carbon steel substrate corrosion was discussed from a point of electrochemical distribution. 相似文献
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Correlation between current frequency and electrochemical properties of Mg alloy coated by micro arc oxidation 总被引:2,自引:0,他引:2
The present work investigated the electrochemical behavior of Mg alloy subjected to micro arc oxidation coating for 120 s with respect to current frequencies from 60 Hz to 2000 Hz. The microstructure and chemical compound of thin coating layers with a thickness of ~ 3 μm were analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy. The microstructural observations on the surface and cross sections revealed that both the size of pores and the number of discharge channels decreased significantly as the current frequency increased, resulting in a compact coating layer. This was primarily attributed to the transition time of the alternating electrical wave, which was determined by the current frequencies tested. Based on potentiodynamic polarization tests, the sample coated at a frequency of 2000 Hz demonstrated the highest polarization resistance of 6.37 × 105 Ω cm2, implying that the corrosion resistance was superior to that obtained under other conditions due to its condensed structure. This electrochemical response was also interpreted in relation to the equivalent circuit model. 相似文献
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针对兼作补偿无功功率用的滤波器的特点,本文介绍了在设计滤波器中值得注意的几个问题,并进行了详细分析及探讨。在工程设计中具有很好的借鉴价值。 相似文献
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GMAW焊接过程的非线性决定了其混沌特性,关联维数是对动力系统混沌特性进行定量分析的主要指标.文中采用相空间重构方法,通过计算关联维数,对GMAW焊接过程中电流信号时间序列进行分析;并改变焊接电压、焊接电流、气体流量等工艺参数,研究不同参数下弧焊过程的混沌特性.结果表明,GMAW焊接过程的混沌现象,不仅存在于短路过渡当中,也存在于滴状过渡中.在此基础上,进一步研究了关联维数随焊接参数的变化规律,认为关联维数可作为焊接过程稳定性评价的依据,即关联维数越小,焊接过程越稳定,焊接工艺参数越优化.上述判据对焊接工艺参数选择的工艺优化试验,焊接过程稳定性监控提供了混沌判识的理论基础. 相似文献
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The results are presented of the investigation of the effect of the surfacing parameters on the penetration area and the thermal efficiency in the conditions of constant heat input in automatic deposition of a bead on a thick component. Correction coefficients used to determine by calculations the penetration area using the well-known and corrected Rykalin equation for a spot constantly acting rapidly moving heat source on the surface of a thick component are derived. 相似文献
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V. V. Starkov D. M. Sedlovets M. A. Knyazev A. N. Red’kin 《Protection of Metals and Physical Chemistry of Surfaces》2017,53(1):85-87
In this work, the results of formation of composite membranes with a thickness of about 200 μm with a high electric conduction based on porous silicon and graphene-like films have been presented. A method of CVD film synthesis that makes it possible to form a graphene-like coating on the inner surface of gradient-porous silicon with variable pore morphology across the thickness has been proposed. The pore sizes vary gradually from units of nanometers on the upper surface to several micrometers deep in silicon. 相似文献
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电极和保温剂对脉冲电流细化晶粒的影响 总被引:1,自引:0,他引:1
在实际的铸造过程中应用脉冲电流要求电极插入熔体中并在熔体的上面覆盖保温剂.为了探明这两个因素对脉冲电流细化组织的影响,采用不同电极或不同保温剂进行了3组实验.通过比较不同条件下得到的凝固组织,发现在脉冲电流作用下电极和保温剂都对凝固组织的细化有明显的影响.进一步的分析表明,液面在凝固组织的细化中起到了关键性的作用,而且结果也支持了在脉冲电流作用下等轴晶主要来自液面的观点. 相似文献
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文章研究了KOCKS轧机三辊切线孔型生产圆棒时轧件的横截面积与KOCKS轧机孔型参数、轧件初始断面之间的关系,并给出相关数学模型。利用宝特棒材生产线上采集的数据,以轧件道次延伸率的计算值与实际值误差标准差最小为目标优化模型中的系数,使道次延伸率计算结果误差在±1%以内,说明模型可以为KOCKS孔型参数设计和优化提供参考。计算了轧件在KOCKS轧机孔型中轧制时的平均应变、应变速率、轧制力、轧制力矩等力能参数,并将轧制力矩的计算值与实测值进行比较,误差范围多在±5%以内,说明模型具有一定精度,可以为轧机负荷设定及调整提供参考。 相似文献
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Summary This study deals with shielded metal arc (manual metal arc, MMA) welding and CO2 gas shielded arc welding, measuring the force required to remove adhering spatter from the surface of base metal by using different filler metals and by changing the conditions of the surface of the base metal. Rolled steel for general structural use (SS400) was used as base metal. A high titanium oxide type electrode and a low hydrogen type electrode were used for shielded metal arc welding, a solid wire and a flux‐cored wire were used as filler metal for CO2 gas shielded arc welding respectively. In order to examine the relationship between the condition of the surface of the base metal and the force required to remove spatter, a base metal whose surface was ground by an electric grinder, one which was not ground by an electric grinder, and another which was coated with an anti‐spatter compound were used for the experiments. Whichever filler metal was used, the spatter which adhered to the surface of the base metal was located within 100 millimetres from the weld line. In those cases, the force required to remove the adhering spatter can be measured as mostly below 98 N. The spatter needing more than 98 N to remove was located mostly within 20 mm of the weld line. No matter whether the scale was on the base metal or not, the difference of the force required to remove the spatter was small. When we used the base metal coated with anti‐spatter compound, in some cases we found spatter on the base metal, and in other cases we did not. When we found spatter, it was located within 40 millimetres of the weld line and the force required to remove it was below 20 N. 相似文献
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Yuichi Tamura 《Corrosion Science》2009,51(7):1560-223
Effect of surface oxide on Pt-Co alloy electrodes on the oxygen reduction reaction (ORR) was investigated in 0.5 M sulfuric acid solution by electrochemistry, ellipsometry, laser Raman scattering spectroscopy, and XPS. The oxide as thick as 1-2 nm increases the overpotential of ORR and falls down efficiency of PEFC. The thickness of the oxide films is precisely determined by ellipsometry. The oxide film 1.9 nm thick was formed on Pt-50 mol% Co electrode by constant potential oxidation at 1.20 V and the film 1.5 nm thick remains on the electrode at 0.6 V at which ORR already starts. The remaining oxide decreases the current density of ORR and increases the overpotential. On pure Pt electrode, the similar influence of the oxide film was observed. 相似文献
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Four compositions of alloys were designed. They were Cu-2% In, Cu-7% In, Cu-11% In and Cu-23% In(mass fraction). These alloy specimens were prepared by metal mold. By means of microstructure observation,macrostructure observation and electron probe analyzing, microstructures and macrostructures of the specimens were analyzed by comparison method. Microstructure component and relationship between structure and composition of alloys were investigated. The results show that with increasing indium content, the grain changes from columnar one to equiaxed one, the equiaxed grain increases, the columnar grain zone decreases and the grain size becomessmall. With increasing indium content, the growth way changes from planar one to dendritic one. Peritectic reaction plays inhibiting role on the growth of dendrite and affects the orientation of dendrite. Indium content has influence on lattice constant of Cu solid solution 相似文献
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