为弥补传统型式试验项目对断路器弧触头状态检测的缺失,文中提出了一种利用动静触头之间动态电阻曲线诊断弧触头状态的方法。试验通过断路器合成试验回路电流源部分对某试品断路器进行了从开断额定短路电流(有效值40 k A)零次到额定次数...为弥补传统型式试验项目对断路器弧触头状态检测的缺失,文中提出了一种利用动静触头之间动态电阻曲线诊断弧触头状态的方法。试验通过断路器合成试验回路电流源部分对某试品断路器进行了从开断额定短路电流(有效值40 k A)零次到额定次数(22次)的烧蚀老化试验,每次烧蚀后测量其弧触头动态电阻曲线,并将与零烧损状态的曲线之间的相关系数作为弧触头烧损状态诊断的特征参数,从测试结果中发现在断路器第15次开断之后相关系数开始出现明显的变化,该现象表明弧触头寿命已经接近工作极限。试验结果证明,动态电阻曲线能够很好地反映出弧触头的烧损情况,是一种有效的SF6断路器弧触头状态诊断方法。展开更多
The damage characteristics of different speed sections of Cu−Cr−Zr alloy rail after simulated launch were studied.The microstructure,morphologies and properties of samples were investigated by using XRD,XPS,EBSD,SEM,h...The damage characteristics of different speed sections of Cu−Cr−Zr alloy rail after simulated launch were studied.The microstructure,morphologies and properties of samples were investigated by using XRD,XPS,EBSD,SEM,hardness test,electrochemical test and DSC techniques.It was found that deposition layers were formed on the surfaces of the simulated launch samples.The thickness and surface roughness of these deposition layers increased with increasing the heat effect,suggesting a launch speed dependent damage degree of the arc ablation.The hardness variation of samples is attributed to the effects of the deposition layer and deformation hardening.The surface deposition layer affects corrosion resistance and crystalline characteristics,leading to changes in subsequent service performances.Additionally,the surface texture and plastic deformation ability of the samples are related to the recrystallization degree and deformation grain amount.展开更多
New types of refractory materials need to be developed for designing the man-made ledge of the Hall-Heroult cell for aluminum electrolysis, which are currently constructed by frozen ledge.Magnesium aluminate spinel （...New types of refractory materials need to be developed for designing the man-made ledge of the Hall-Heroult cell for aluminum electrolysis, which are currently constructed by frozen ledge.Magnesium aluminate spinel （MAS） as potential candidate materials was prepared by two-step sintering. The densification and grain growth of the MAS wereinvestigatedbytheArchimedes drainage method and scanning electron microscope （SEM）. All the specimens were corroded in aNa3AlF6-AlF3-CaF2-Al2O3bath to assess the corrosion resistance. The results show that a MAS material with a high relative density of 99.2% and ahomogeneous microstructure is achieved under two-step sintering conditions. The corrosion mechanisms of MAS inNa3AlF6-AlF3-CaF2-Al2O3 bathare mainly proposed by dissolution of MAS, formation of aluminum oxide, and diffusion of fluorides. The MAS prepared by two-step sintering exhibits good corrosion resistance to theNa3AlF6-AlF3-CaF2-Al2O3bath.展开更多
Resonance-enhanced multiphoton ionization of the titanium atoms has been investigated in the 293 321 nm wavelength. We couple a laser-ablated metal target into a molecular beam to produce free atoms. Ions produced fro...Resonance-enhanced multiphoton ionization of the titanium atoms has been investigated in the 293 321 nm wavelength. We couple a laser-ablated metal target into a molecular beam to produce free atoms. Ions produced from photoionization of the neutral atoms are monitored by a home-built time-of-flight mass spectrometer. Photoionization cross sections of the excited states of Ti I were deduced from the dependence of the ion signal intensity on the laser intensity for photon energies close to the ionization threshold. The values obtained range from 0.2 Mb to 6.0 Mb. No significant isotope-dependence was found from measurements of the photoionization cross sections of ^46Ti, ^47Ti, and ^48Ti.展开更多
A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were te...A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.展开更多
文摘为弥补传统型式试验项目对断路器弧触头状态检测的缺失,文中提出了一种利用动静触头之间动态电阻曲线诊断弧触头状态的方法。试验通过断路器合成试验回路电流源部分对某试品断路器进行了从开断额定短路电流(有效值40 k A)零次到额定次数(22次)的烧蚀老化试验,每次烧蚀后测量其弧触头动态电阻曲线,并将与零烧损状态的曲线之间的相关系数作为弧触头烧损状态诊断的特征参数,从测试结果中发现在断路器第15次开断之后相关系数开始出现明显的变化,该现象表明弧触头寿命已经接近工作极限。试验结果证明,动态电阻曲线能够很好地反映出弧触头的烧损情况,是一种有效的SF6断路器弧触头状态诊断方法。
基金the Key Research and Development Program of China(No.2022YFB2404102)the National Natural Science Foundation of China(Nos.51971093,52171158,52101196)+5 种基金the Key Research and Development Program of Shandong Province,China(Nos.2020ZLYS11,2021ZLGX01,2022CXGC020308,2023CXGC010308)the Major Innovation Projects of Shandong Province,China(Nos.2020CXGC010701,2020CXGC010702)the Young Taishan Scholars,China(No.tsqn202211184)the Shandong Provincial Natural Science Foundation,China(No.ZR2022ME137)the Yantai Science and Technology Planning Project,China(No.2021ZDCX001)the Open Project Program of Shandong Marine Aerospace Equipment Technological Innovation Center(Ludong University),China(No.MAETIC2021-11).
文摘The damage characteristics of different speed sections of Cu−Cr−Zr alloy rail after simulated launch were studied.The microstructure,morphologies and properties of samples were investigated by using XRD,XPS,EBSD,SEM,hardness test,electrochemical test and DSC techniques.It was found that deposition layers were formed on the surfaces of the simulated launch samples.The thickness and surface roughness of these deposition layers increased with increasing the heat effect,suggesting a launch speed dependent damage degree of the arc ablation.The hardness variation of samples is attributed to the effects of the deposition layer and deformation hardening.The surface deposition layer affects corrosion resistance and crystalline characteristics,leading to changes in subsequent service performances.Additionally,the surface texture and plastic deformation ability of the samples are related to the recrystallization degree and deformation grain amount.
基金Project(51374240)supported by the National Natural Science Foundation of ChinaProject(2012BAE08B02)supported by the National Science and Technology Pillar Program of China
文摘New types of refractory materials need to be developed for designing the man-made ledge of the Hall-Heroult cell for aluminum electrolysis, which are currently constructed by frozen ledge.Magnesium aluminate spinel （MAS） as potential candidate materials was prepared by two-step sintering. The densification and grain growth of the MAS wereinvestigatedbytheArchimedes drainage method and scanning electron microscope （SEM）. All the specimens were corroded in aNa3AlF6-AlF3-CaF2-Al2O3bath to assess the corrosion resistance. The results show that a MAS material with a high relative density of 99.2% and ahomogeneous microstructure is achieved under two-step sintering conditions. The corrosion mechanisms of MAS inNa3AlF6-AlF3-CaF2-Al2O3 bathare mainly proposed by dissolution of MAS, formation of aluminum oxide, and diffusion of fluorides. The MAS prepared by two-step sintering exhibits good corrosion resistance to theNa3AlF6-AlF3-CaF2-Al2O3bath.
基金V. ACKNOWLEDGMENTS This work is supported by the National Natural Science Foundation of China （No.10674002 and No.20973001） and the Science Foundation of Anhui Education Committee （No.ZD2007001-1）.
文摘Resonance-enhanced multiphoton ionization of the titanium atoms has been investigated in the 293 321 nm wavelength. We couple a laser-ablated metal target into a molecular beam to produce free atoms. Ions produced from photoionization of the neutral atoms are monitored by a home-built time-of-flight mass spectrometer. Photoionization cross sections of the excited states of Ti I were deduced from the dependence of the ion signal intensity on the laser intensity for photon energies close to the ionization threshold. The values obtained range from 0.2 Mb to 6.0 Mb. No significant isotope-dependence was found from measurements of the photoionization cross sections of ^46Ti, ^47Ti, and ^48Ti.
基金Supported by National High Technology Research and Development Program of China ("863"Program) (No.2006AA04Z327)National Natural Science Foundation of China (No.60372006)Program for New Century Excellent Talents in University
文摘A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.
