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Asphaltene Erosion Process in Air Plasma: Emission Spectroscopy and surface analysis for Air-Plasma Reactions

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Plasma Science and Technology 2012年第4期14卷 303-311页

作者： H.MARTINEZ O. FLORES J.C. POVEDA B. CAMPILLO Institute of Physical Sciences Autonomous National University of Mexico Chemistry Faculty Autonomous National University of Mexico

Optical emission spectroscopy （OES） was applied for plasma characterization during the erosion of asphaltene substrates. An amount of 100 mg of asphaltene was carefully applied to an electrode and exposed to air-plasma glow discharge at a pressure of 1.0 Torr. The plasma was generated in a stainless steel discharge chamber by an ac generator at a frequency of 60 Hz, output power of 50 W and a gas flow rate of 1.8 L/min. The electron temperature and ion density were estimated to be 2.15±0.11 eV and （1.24±0.05）× 10^16 m^-3, respectively, using a double Langmuir probe. OES was employed to observe the emission from the asphaltene exposed to air plasma. Both molecular band emission from N2, N2＋, OH, CH, NH, O2 as well as CN, and atomic light emission from V and Hγ were observed and used to monitor the evolution of asphaltene erosion. The asphaltene erosion was analyzed with the aid of a scanning electron microscope （SEM） equipped with an energy dispersive X-ray （EDX） detector. The EDX analysis showed that the time evolution of elements C, O, S and V were similar and the chemical composition of the exposed asphaltenes remained constant. Particle size evolution was measured, showing a maximum size of 2307 μm after 60 min. This behavior is most likely related to particle agglomeration as a function of time.

关键词： asphaltene erosion surface analysis optical emission spectroscopy pulsedplasma glow discharge

Wear mechanism of heavy load friction contact pairs in tracked vehicle by combined ferrography and surface analysis

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中国有色金属学会会刊:英文版 2004年第z1期14卷 348-353页

作者： LI Li ZHU You-li HUANG Yuan-lin XU Bin-shi LI Xiao-yan National Key Laboratory for Remanufacturing Academy of Armored Force EngineeringBeijing 100072 China College of Materials Science and Engineering Beijng University of TechnologyBeijing 100022 China

Ferrography is deemed as one of the most effective methods for wear particle analysis and failure diagnosis. By analyzing the configuration, content and composition of wear particles in the lubricanting grease and the surface state of the worn surface with combined ferrography and surface analysis techniques, the wear mechanism of the ball groove of the master clutch's release device of a heavy load tracked vehicle was determined. Results show that the controlling wear mechanism is combined of abrasion, adhesion, contact fatigue and corrosion wear, which demonstrates the effectiveness of using combined ferrography and worn surface analysis for the study of wear mechanism of contact surface with friction.

关键词： ferrography surface analysis wear failure analysis lubricanting grease

Hydroisomerization of n-Pentane over Zn-Fe-S₂O₈-2/ZrO₂-Al₂O₃ Superacid Catalyst: Activity, surface analysis and the Investigation of Deactivation and Regeneration

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Open Journal of Inorganic Chemistry 2023年第3期13卷 43-59页

作者： Huapeng Cui Shengnan Li Key Laboratory of Transient Physical Mechanics and Energy Conversion Materials of Liaoning Province Shenyang Ligong University Shenyang China China Petroleum Pipeline Engineering Corporation Langfang China

The Zn and Fe modified /ZrO2-Al2O3 catalyst (Zn-Fe-SZA) was prepared and mechanisms of deactivation and methods for regeneration of as-prepared catalyst were explored with n-pentane isomerization as a probe reaction. The results indicated that the isopentane yield of the fresh Zn-Fe-SZA-F catalyst was about 57% at the beginning of the run, and declined gradually to 50% within 1500 min, then fell rapidly from 50% to 40% between 1500 and 2500 minutes. The deactivation of Zn-Fe-SZA catalyst may be caused by carbon formation on surface of the catalyst, sulfate group attenuation owing to reduction by hydrogen, removal of sulfur species and the loss of strong acid sites. It was found that the initial catalytic activity over Zn-Fe-SZA-T catalyst was 48%, which recovered by 84.3% as compared to that of fresh catalyst (57%). However, it showed a sharp decrease in isopentane yield from 48% to 29% within 1500 minutes, showing poor stability. This is associated to the loss of acidity caused by removal of sulfur species cannot be basically restored by thermal treatment. Resulfating the calcined catalyst could improve the acidity of catalyst significantly, especially strong acid sites, as compared with the calcined sample. The improved stability of the resulfated catalyst can be explained by: 1) eliminaton of carbon deposition to some extent by calcination process, 2) formation of improved acidic nature by re-sulfation, favoring isomerization on acidic sites, 3) restructuring of the acid and metal sites via the calcination-re-sulfation procedure.

关键词： Zn-Fe Solid Superacid surface analysis Deactivation Regeneration Hydroisomerization

Photoconductivity and surface chemical analysis of ZnO thin films deposited by solution-processing techniques for nano and microstructure fabrication

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Journal of Semiconductors 2013年第3期34卷 12-16页

作者： V.K.Dwivedi P.Srivastava G.Vijaya Prakash Nanophotonics Laboratory Department of PhysicsIndian Institute of Technology DelhiHauz khasNew Delhi-110 016India Nanostech Laboratory Department of PhysicsIndian Institute of Technology DelhiHauz khasNew Delhi-110 016India Nanophotonics Laboratory Department of PhysicsIndian Institute of Technology DelhiHauz khasNew Delhi-110016India

The fabrication of zinc oxide(ZnO) from inexpensive solution-processing techniques,namely,electrochemical deposition and electrospinning were explored on various conducting and mesoporous semiconducting *** conditions were derived for template- and self-assisted nano/micro structures and composites. ZnO thin films were annealed at a fixed temperature under ambient conditions and characterised using physical and optical *** photocurrent response in the UV region shows a fast rise and double decay behaviour with a fast component followed by a slow oscillatory *** results were correlated with surface chemical analysis from X-ray photoelectron *** characterisation details reveal the importance of fabrication parameter optimisation for useful low-cost optoelectronic applications.

关键词： zinc oxide electrochemical deposition surface analysis X-ray photoelectron spectroscopy photocurrent response optoelectronic applications

Three-dimensional finite element analysis of shallow indentation of rough strain-hardening surface

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Friction 2019年第6期7卷 587-602页

作者： Chenghui GAO Henry PROUDHON Ming LIU School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350116China Centre des Matériaux MINES Paris TechEvry Cedex 91003France

Three-dimensional finite element modeling of the contact between a rigid spherical indenter and a rough surface is presented when considering both the loading and unloading phases. The relationships among the indentation load, displacement, contact area, and mean contact pressure for both loading and unloading are established through a curve fitting using sigmoid logistic and power law functions. The contact load is proportional to the contact area, and the mean contact pressure is related to the characteristic stress, which is dependent on the material properties. The residual displacement is proportional to the maximum indentation displacement. A proportional relationship also exists for plastically dissipated energy and work conducted during loading. The surface roughness results in an effective elastic modulus calculated from an initial unloading stiffness several times larger than the true value of elastic modulus. Nonetheless, the calculated modulus under a shallow spherical indentation can still be applied for a relative comparison.

关键词： finite element modeling surface analysis contact mechanics indentation spherical indenter

Characterization of the tribologically relevant cover layers formed on copper in oxygen and oxygen-free conditions

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Friction 2023年第8期11卷 1505-1521页

作者： Selina RAUMEL Khemais BARIENTI Hoang-Thien LUU Nina MERKERT Folke DENCKER Florian NÜRNBERGER Hans Jürgen MAIER Marc Christopher WURZ Institute of Micro Production Technology Leibniz Universität HannoverGarbsen 30823Germany Institut für Werkstoffkunde(Materials Science) Leibniz Universität HannoverGarbsen 30823Germany Institute of Applied Mechanics Clausthal University of TechnologyClausthal-Zellerfeld 38678Germany

Engineering in vacuum or under a protective atmosphere permits the production of materials, wherever the absence of oxygen is an essential demand for a successful processing. However, very few studies have provided quantitative evidence of the effect of oxidized surfaces to tribological properties. In the current study on 99.99% pure copper, it is revealed that tribo-oxidation and the resulting increased abrasive wear can be suppressed by processing in an extreme high vacuum (XHV) adequate environment. The XHV adequate atmosphere was realized by using a silane-doped shielding gas (1.5 vol% SiH4 in argon). To analyse the influence of the ambient atmosphere on the tribological and mechanical properties, a ball–disk tribometer and a nanoindenter were used in air, argon, and silane-doped argon atmosphere for temperatures up to 800 ℃. Resistance measurements of the resulting coatings were carried out. To characterize the microstructures and the chemical compositions of the samples, the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used. The investigations have revealed a formation of η-Cu3Si in silane-doped atmosphere at 300 ℃, as well as various intermediate stages of copper silicides. At temperatures above 300 ℃, the formation of γ-Cu5Si were detected. The formation was linked to an increase in hardness from 1.95 to 5.44 GPa, while the Young’s modulus increased by 46% to 178 GPa, with the significant reduction of the wear volume by a factor of 4.5 and the suppression of further oxidation and susceptibility of chemical wear. In addition, the relevant diffusion processes were identified using molecular dynamics (MD) simulations.

关键词： wear behavior tribochemical reaction oxidation behavior surface analysis molecular dynamics(MD)simulation

A Comparative Study on Asperity Peak Modeling Methods

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Chinese Journal of Mechanical Engineering 2021年第4期34卷 137-150页

作者： Wei Zhou Daiyan Zhao Jinyuan Tang Jun Yi Hunan Provincial Key Laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material Hunan University of Science and TechnologyXiangtan 411201China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China

The peak identification scheme based method(three-point definition)and the spectral moments based method(spectral moment approach)are both widely used for asperity peak modeling in *** discover the differences between the two methods,a great number of rough surface profile samples with various statistical distributions are first randomly generated using *** the distribution parameters of asperity peaks are calculated for the generated samples with both *** obtained results are compared and verified by *** variation rules of the differences between the two methods with statistical characteristics of rough surfaces are *** explain for the discovered differences,the assumptions by spectral moment approach that the joint distribution of surface height,slope and curvature is normal and that the height distribution of asperities is Gaussian,are *** results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of[z],[z′]and[z′′],and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent,20 for instance.

关键词： surface topography Roughness surface analysis Asperity peak Random process model

Dry Sliding Tribological Properties of a Dendrite-reinforced Zr-based Bulk Metallic Glass Matrix Composite

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Journal of Materials Science & Technology 2014年第6期30卷 576-583页

作者： Huijun Yang Yong Liu Teng Zhang Hengpeng Wang Bin Tang Junwei Qiao Research Institute of surface Engineering Taiyuan University of Technology Laboratory of Applied Physics and Mechanics of Advanced Materials College of Materials Science and Engineering Taiyuan University of Technology

In-situ dendrite-reinforced metallic glass matrix （MGM） composites with the composition of Zr58.5Ti14.3Nb5.2Cu6.1Ni4.9Be11.0 were prepared with a vacuum arc melter by the copper mold suction casting. Effect of different normal loads and sliding velocities on the tribological properties of MGM composites was studied. The results showed that the friction coefficient and wear rate of composites initially descended with increasing the normal load and reached a minimum of 0.339 and 1.826 × 10^-4 mm^3/（N m） at 10 N, respectively, then ascended. Similarly, the friction coefficient and wear rate of composites initially decreased with the increase in the sliding velocity and reached a minimum of 0.330 and 2.389 × 10^-4 mm^3/（N m） at 0.4 m/s and 0.3 m/s, respectively, then raised. The wear mechanism of composites was mainly adhesive wear accompanied by abrasive wear at lower normal load and sliding velocity. However, the wear mechanism of composites was abrasive wear and adhesive wear as well as delamination at higher normal load and sliding velocity due to the nucleation and propagation of surface and subsurface cracks during the wear process. The flake-like and particle-like wear debris was the dominant shapes of debris observed.

关键词： Sliding wear Sliding friction surface topography surface analysis Wear testing

In vitro Cyto and Blood Compatibility of Titanium Containing Diamond-Like Carbon Prepared by Hybrid Sputtering Method

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Plasma Science and Technology 2012年第9期14卷 829-836页

作者： Krishnasamy NAVANEETHA PANDIYARAJ Jan HEEG Andreas LAMPKA Fabian JUNGE Torsten BARFELS Marion WIENECKE Young Ha RHEE Hyoung Woo KIM Department of Physics Sri Shakthi Institute of Engineering and Technology Institute of surface and Thin Film Technology Hochschule WismarGermany Department of Microbiology College of Bioscience&BiotechnologyChungnam National University

In recent years, diamond-like carbon films （DLC） have been given more attention in research in the biomedical industry due to their potential application as surface coating on biomedical materials such as metals and polymer substrates. There are many ways to prepare metal containing DLC films deposited on polymeric film substrates, such as coatings from car- bonaceous precursors and some means that incorporate other elements. In this study, we in- vestigated both the surface and biocompatible properties of titanium containing DLC （Ti-DLC） films. The Ti-DLC films were prepared on the surface of poly （ethylene terephthalate）（PET） film as a function of the deposition power level using reactive sputtering technique. The films＇ hydrophilicity was studied by contact angle and surface energy tests. Their surface morphology was studied by scanning electron microscopy （SEM） and atomic force microscopy （AFM）. Their elemental chemical composition was analyzed using energy dispersive X-spectra （EDX） and X-ray photoelectron spectroscopy （XPS）. Their blood and cell compatibility was studied by in vitro tests, including tests on platelet adhesion, thrombus formation, whole blood clotting time and osteoblast cell compatibility. Significant changes in the morphological and chemical composition of the Ti-DLC films were observed and found to be a function of the deposition level. These morphological and chemical changes reduced the interfacial tension between Ti-DLC and blood proteins as well as resisted the adhesion and activation of platelets on the surface of the Ti-DLC films. The cell compatibility results exhibited significant growth of osteoblast cells on the surface of Ti incorporated DLC film compared with that of DLC film surface.

关键词： Ti-DLC hybrid reactive sputtering technique surface analysis cyto and blood compatibility