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Investigation on the electrode surface roughness effects on a repetitive self-breakdown gas switch

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Plasma Science and Technology 2022年第6期24卷 182-188页

作者：曾凡正李嵩蔡浩张全才韦金红王俊婷刘照华王蕾高景明万红钱宝良 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073People's Republic of China The 93986 Unit Hotan 848000People's Republic of China College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073People's Republic of China

In this work,the influence of the electrode surface roughness on the self-breakdown gas switch is investigated by physical analysis,computer simulation and ***-W electrodes of different surface roughness were tested under the conditions of a pulse repetitive frequency of50 Hz,self-breakdown voltage of~30 kV,and peak current of~2 k A for~93000 shots(the total charge transferred was~15 C).The coefficients of variation of the self-breakdown voltage of Cu-W 0.8,Cu-W 3.2 and Cu-W 12.5 electrodes were~2.95%,~1.62%and~1.16%,*** the increase of electrode roughness,the erosion area decreased continuously,indicating that the breakdown positions were more stable and the coefficient of variation of breakdown voltage *** method showed that decreasing the coefficient of variation of the self-breakdown voltage by increasing the surface roughness of electrode greatly improves the stability of the self-breakdown switch,which is significant for their application in compact highpower pulse power devices over a long time with stable operation.

关键词： gas switch self-breakdown surface roughness coefficient of variation

Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding

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Chinese Journal of Aeronautics 2015年第2期28卷 570-581页

作者： Zhang Dongkun Li Changhe Jia Dongzhou Zhang Yanbin Zhang Xiaowei School of Mechanical Engineering Qingdao Technological University

Nanoparticles with the anti-wear and friction reducing features were applied as cooling lubricant in the grinding fluid. Dry grinding, flood grinding, minimal quantity of lubrication （MQL）, and nanoparticle jet MQL were used in the grinding experiments. The specific grinding energy of dry grinding, flood grinding and MQL were 84, 29.8, 45.5 J/mm3, respectively. The speci- fic grinding energy significantly decreased to 32.7 J/mm3 in nanoparticle MQL. Compared with dry grinding, the surface roughness values of flood grinding, MQL, and nanoparticle jet MQL were sig- nificantly reduced with the surface topography profile values reduced by 11%, 2.5%, and 10%, respectively, and the ten point height of microcosmic unflatness values reduced by 1.5%, 0.5%, and 1.3%, respectively. These results verified the satisfactory lubrication effects of nanoparticle MQL. MoS：, carbon nanotube （CNT）, and ZrO2 nanoparticles were also added in the grinding fluid of nanoparticle jet MQL to analyze their grinding surface lubrication effects. The specific grinding energy of MoS2 nanoparticle was only 32.7 J/mm3, which was 8.22% and 10.39% lower than those of the other two nanoparticles. Moreover, the surface roughness of workpiece was also smaller with MoS2 nanoparticle, which indicated its remarkable lubrication effects. Furthermore, the role of MoS2 particles in the grinding surface lubrication at different nanoparticle volume con- centrations was analyzed. MoS2 volume concentrations of 1%, 2%, and 3% were used. Experimental results revealed that the specific grinding energy and the workpiece surface roughness initially increased and then decreased as MoS2 nanoparticle volume concentration increased. Satisfactory grinding surface lubrication effects were obtained with 2% MoS2 nanoparticle volume concentration.

关键词： Grinding Minimal quantity of lubrica-tion (MQL) Nanoparticle Specific grinding energy surface roughness

Investigation of working pressure on the surface roughness controlling technology of glow discharge polymer films based on the diagnosed plasma

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Plasma Science and Technology 2017年第7期19卷 110-117页

作者：张玲陈果何智兵艾星黄景林刘磊唐永建何小珊 Research Center of Laser Fusion China Academy of Engineering Physics

The effects of working pressure on the component, surface morphology, surface roughness, and deposition rate of glow discharge polymer （GDP） films by a trans-2-butene/hydrogen gas mixture were investigated based on plasma characteristics diagnosis. The composition and ion energy distributions of a multi-carbon （CaHs/H2） plasma mixture at different working pressures were diagnosed by an energy-resolved mass spectrometer （MS） during the GDP film deposition process. The Fourier transform infrared spectroscopy （FT-IR）, field emission scanning electron microscope （SEM） and white-fight interferometer （WLI） results were obtained to investigate the structure, morphology and roughness characterization of the deposited films, respectively. It was found that the degree of ionization of the C4H8/H2 plasma reduces with an increase in the working pressure. At a low working pressure, the C-H fragments exhibited small-mass and high ion energy in plasma. In this case, the film had a low CH3/CH2 ratio, and displayed a smooth surface without any holes, cracks or asperities. While the working pressure increased to 15 Pa, the largest number of large-mass fragments led to the deposition rate reaching a maximum of 2.11 #m h-1, and to hole defects on the film surface. However, continuing to increase the working pressure, the film surface became smooth again, and the interface between clusters became inconspicuous without etching pits.

关键词： glow discharge polymer films plasma diagnosis working pressure surfacemorphology surface roughness

Effects of surface roughness on the aerodynamic performance of a high subsonic compressor airfoil at low Reynolds number

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Chinese Journal of Aeronautics 2021年第3期34卷 71-81页

作者： Mingyang WANG Chengwu YANG Ziliang LI Shengfeng ZHAO Yanfeng ZHANG Xin’gen LU Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The aerodynamic performance of compressor airfoil is significantly affected by the surface roughness at low Reynolds number(Re).In the present study,numerical simulations have been conducted to investigate the impact of surface roughness on the profile loss of a high subsonic compressor airfoil at Re=1.5×10^(5).Four roughness locations,covering 10%,30%,50%and 100%of the suction surface from the leading edge and seven roughness magnitudes(Ra)ranging from 52 to525 lm were *** showed that the surface roughness mainly determined the loss generation process by influencing the structure of the Laminar Separation Bubble(LSB)and the turbulence level near the *** all the roughness locations,the variation trend for the profile loss with the roughness magnitude was *** the transitionally rough region,the negative displacement effect of the LSB was suppressed with the increase of roughness magnitude,leading to a maximum decrease of 14.6%,16.04%,16.45%and 10.20%in the profile loss at Ra=157 lm for the four roughness locations,***,with a further increase of the roughness magnitude in the fully rough region,the stronger turbulent dissipation enhanced the growth rate of the turbulent boundary layer and increased the profile loss *** comparison,the leading edge roughness played a dominant role in the boundary layer development and performance *** take fully advantage of the surface roughness reducing profile loss at low Re,the effects of roughness on suppressing LSB and inducing strong turbulent dissipation should be balanced effectively.

关键词： Aerodynamic performance Compressor airfoil Low Reynolds number Separation bubble surface roughness Viscous dissipation

Measurement and analysis of the surface roughness of Ag film used in plasmonic lithography

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Chinese Physics B 2017年第1期26卷 363-368页

作者：梁高峰焦蛟罗先刚赵青 School of Physical Electronics University of Electronic Science and Technology of China State Key Laboratory of Optical Technologies for Microfabrication Institute of Optics and ElectronicsChinese Academy of Sciences

The silver（Ag）/photoresist（PR）/Ag structure, widely used in plasmonic photolithography, is fabricated on silicon substrate. The surface roughness of the top Ag film is measured and analyzed systematically. In particular, combined with template stripping technology, the lower side of the top Ag film is imaged by an atomic force microscope. The topographies show that the lower side surface is rougher than the initial surface of the subjacent PR film, which is mainly attributable to the deformation caused by particle collisions during the deposition of the Ag film. Additionally, further measurements show that the Ag film deposited on the PR exhibits a flatter upper side morphology than that directly deposited on the silicon substrate. This is explained by the different growth modes of Ag films on different substrates. This work will be beneficial to morphology analysis and performance evaluation for the films in optical and plasmonic devices.

关键词： surface roughness lithography silver film deposition

Study on contact fatigue of a wind turbine gear pair considering surface roughness

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Friction 2020年第3期8卷 553-567页

作者： Heli LIU Huaiju LIU Caichao ZHU Zhangdong SUN Houyi BAI State Key Laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400030China Hubei University of Automotive Technology Shiyan 442002HubeiChina Chongqing Wangjiang Industrial Co.Chongqing 400071China

Contact fatigue issues become more and more crucial in gear industry as they significantly affect the reliability and service life of associated mechanical systems such as wind turbine *** contact fatigue behavior is mostly determined by the mechanical properties of materials and stress fields near the contact area,which is further influenced by the lubrication and surface roughness due to pressure *** this study,a numerical model incorporating the lubrication state,tooth surface roughness,residual stress,and mechanical properties of the material is developed to determine the contact fatigue behavior of a megawatt level wind turbine carburized *** variations of the hardness and residual stress along the depth were characterized by the Vickers hardness measurement and X-ray diffraction test,*** elastohydrodynamic lubrication theory was applied to predict the contact pressure distribution,highlighting the influence of the surface roughness that stemed from the original measurement through an optical *** stress histories of the studied material points during a complete contact loading cycle were fast calculated using the discreteconcrete fast Fourier transformation(DC-FFT)*** Dang Van diagrams under different working conditions were determined to estimate the contact fatigue failure *** effect of the root mean square(RMS)value of the surface roughness on the failure risk at critical material points were discussed in *** revealed that the surface roughness significantly increases the contact fatigue failure risk within a shallow area,and the maximum risk appears near the surface.

关键词： carburized gear contact fatigue surface roughness residual stress Dang Van criterion

Modelling the combined effect of surface roughness and topography on bacterial attachment

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Journal of Materials Science & Technology 2021年第22期81卷 151-161页

作者： Subash Bommu Chinnaraj Pahala Gedara Jayathilake Jack Dawson Yasmine Ammar Jose Portoles Nicholas Jakubovics Jinju Chen School of Engineering Newcastle UniversityNewcastle Upon TyneUK Department of Oncology University of OxfordUK School of Dental Sciences Newcastle UniversityNewcastle Upon TyneUK

Bacterial attachment is a complex process affected by flow conditions,imparted stresses,and the surface properties and structure of both the supporting material and the *** on the initial attachment of cells of the bacterium Streptococcus gordonii(***),an important early coloniser of dental plaque,to samples of stainless steel(SS)have been reported in this *** primary aim motivating this study was to establish what affect,if any,the surface roughness and topology of samples of SS would have on the initial attachment of cells of the bacterium *** material and bacterium were chosen by virtue of their relevance to dental implants and dental implant *** to bacterial attachment,surfaces become conditioned by the interfacing environment(salivary pellicle from the oral cavity for instance).For this reason,cell attachment to samples of SS pre-coated with saliva was also *** implementing the Extended Derjaguin Landau Verwey and Overbeek(XDLVO)theory coupled with convection-diffusion-reaction equations and the surface roughness information,a computational model was developed to help better understand the physics of cell *** roughness was modelled by reconstructing the surface topography using statistical parameters derived from atomic force microscopy(AFM)*** this computational model,the effects of roughness and surface patterns on bacterial attachment were examined quantitatively in both static and flowing fluid *** results have shown that rougher surfaces(within the sub-microscale)generally increase bacterial attachment in static fluid conditions which quantitatively agrees with experimental *** flow conditions,computational fluid dynamics(CFD)simulations predicted reduced convection-diffusion inside the channel which would act to decrease bacterial *** combined with surface roughness effects,the computational model also predicted that the surface top

关键词： Bacterial attachment XDLVO theory Computational modelling surface topography surface roughness

Tool Wear and Its Effect on surface roughness in Diamond Cutting of Glass Soda-lime

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Chinese Journal of Mechanical Engineering 2012年第6期25卷 1224-1230页

作者： JIA Peng ZHOU Ming Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun 130033 China School of Mechanical and Electrical Engineering Harbin Institute of Technology Harbin 150001 China

For the technology of diamond cutting of optical glass, the high tool wear rate is a main reason for hindering the practical application of this technology. Many researches on diamond tool wear in glass cutting rest on wear phenomenon describing simply without analyzing the genesis of wear phenomenon and interpreting the formation process of tool wear in mechanics. For in depth understanding of the tool wear and its effect on surface roughness in diamond cutting of glass, experiments of diamond turning with cutting distance increasing gradually are carried out on soda-lime glass. The wear morphology of rake face and flank face, the corresponding surface features of workpiece and the surface roughness, and the material compositions of flank wear area are detected. Experimental results indicate that the flank wear is predominant in diamond cutting glass and the flank wear land is characterized by micro-grooves, some smooth crater on the rake face is also seen. The surface roughness begins to increase rapidly, when the cutting mode changes from ductile to brittle for the aggravation of tool wear with the cutting distance over 150 m. The main mechanisms of inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear. The proposed research makes analysis and research from wear mechanism on the tool wear and its effect on surface roughness in diamond cutting of glass, and provides theoretical basis for minimizing the tool wear in diamond cutting brittle materials, such as optical glass.

关键词： diamond cutting tool wear surface roughness soda-lime glass

Influence of processing parameters on coating surface roughness of aluminum alloy

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Transactions of Nonferrous Metals Society of China 2009年第S2期19卷 392-397页

作者：潘明强迟关心韦东波狄士春 School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China

The influence of processing parameters on the coating surface roughness of LD10 aluminum alloy treated by the power source with positive and negative pulse in the alkaline electrolyte was *** of experiments were done with different processing parameters including the positive final voltage,the negative final voltage,the frequency,the duty ratio,the processing time and electrolyte *** the surface roughness tester TR200 was used to measure the coating surface *** influence of the processing time on the surface roughness is the smallest,less than 0.2μ*** surface roughness decreases gradually with the duty ratio decreasing or the frequency increasing;it decreases gradually with each of the other parameters increasing,and then increases gradually after achieving the minimum *** by selecting processing parameters,the coating with Ra 0.6 can be obtained.

关键词： micro-arc oxidation processing parameter surface roughness aluminum alloy