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Galvanically induced potentials to enable minimal tribochemical wear of stainless steel lubricated with sodium chloride and ionic liquid aqueous solution

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Friction 2018年第2期6卷 230-242页

作者： Tobias AMANN Felix GATTI Natalie OBERLE Andreas KAILER Jürgen RüHE fraunhofer institute for Mechanics of Materials IWM institute for Macromolecular Chemistry University of Freiburg IMTEK-Department of Microsystems Engineering University of Freiburg

The effect of galvanically induced potentials on the friction and wear behavior of a 1 RK91 stainless steel regarding to tribocorrosion was investigated using an oscillating ball-on-disk tribometer equipped with an electrochemical cell. The aim of this investigation is to develop a water-based lubricant. Therefore 1 molar sodium chloride(NaCl) and 1% 1-ethyl-3-methylimidazolium chloride [C_2 mim][Cl] water solutions were used. Tribological performance at two galvanically induced potentials was compared with the non-polarized state: cathodic potential-coupling with pure aluminum- and anodic potential-coupling with pure copper. Frictional and electrochemical response was recorded during the tests. In addition, wear morphology and chemical composition of the steel were analyzed using scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS), respectively. The galvanically induced cathodic polarization of the stainless steel surface results in electrochemical corrosion protection and the formation of a tribolayer. Cations from the electrolyte(sodium Na^+ and 1-ethyl- 3-methylimidazolium [C_2 mim]^+) interact and adhere on the surface. These chemical interactions lead to considerably reduced wear using 1 NaC l(86%) and 1% 1-ethyl-3-methylimidazolium chloride [C_2 mim][Cl](74%) compared to the nonpolarized system. In addition, mechanical and corrosive part of wear was identified using this electrochemical technique. Therefore this method describes a promising method to develop water-based lubricants for technical applications.

关键词： sliding wear tribochemistry potential controlled friction and wear galvanic coupling ionic liquids tribolayer formation

A fast numerical method of introducing the strengthening effect of residual stress and strain to tensile behavior of metal matrix composites

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Journal of Materials Science & Technology 2021年第28期87卷 167-175页

作者： J.F.Zhang X.X.Zhang H.Andrä Q.Z.Wang B.L.Xiao Z.Y.Ma Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China fraunhofer institute for Industrial Mathematics Fraunhofer-Platz 1Kaiserslautern 67663Germany

Thermal residual stress and strain(TRSS)in particle reinforced metal matrix composites(PRMMCs)are believed to cause strengthening effects,according to previous ***,the representative volume element(RVE)based computational homogenization technique was used to study the tensile deformation of PRMMCs with different particle aspect ratios(AR).The influence of TRSS was assessed quantitatively via comparing simulations with or without the cooling *** was found that the strengthening effect of TRSS was affected by the particle *** the average strengthening effect of TRSS,a fast method of introducing the strengthening effect of TRSS to the tensile behavior of PRMMCs was *** new method has reduced the computational cost by a factor *** effect of TRSS on continuous fiber-reinforced metal matrix composite was found to have a softening-effect during the entire tensile deformation process because of the pre-yield effect caused by the cooling process.

关键词： Metal matrix composites(MMC) Finite element analysis(FEA) Representative volume element(RVE) Residual stress and strain Aspect ratio

Measurement of the spatial specific impulse distribution due to buried high explosive charge detonation

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Defence Technology（防务技术） 2017年第3期13卷 219-227页

作者： V. Denefeld N. Heider A. Holzwarth fraunhofer institute for High-Speed Dynamics Ernst-Mach-Institut EMI Ernst-Mach-Institut

Buried high explosive(HE) charges represent a high threat to military vehicles. The detonation of these charges can lead to significant momentum transfer onto vehicles and their occupants. A detailed understanding of the physical processes involved in the loading of vehicle structures is necessary for an optimization of effective countermeasures and protection systems. A quantitative description of the local momentum distribution on the vehicle underbody due to the detonation process is of special importance. In the following, a new test setup is presented that allows the experimental determination of the specific impulse distribution. It is based on a ring arrangement where the elements are nested into each other and the velocity of each ring is correlated with the local specific impulse at its *** momentum transfer to a vehicle depends on a number of influencing factors such as: charge mass,embedding material(e.g. sand, gravel, clay), density, water content, saturation, depth of burial, ground clearance and vehicle shape. The presented technology is applied to quantify the influence of the embedding material(alluvial sand, quartz sand), the burial depth and the water content on the local specific impulse distribution. The obtained data can be used as initial condition for the numerical simulation of occupant safety assessment and as input for empirical modeling of momentum transfer on structures.

关键词：装药爆炸比冲军用车辆测量空间炸药车辆结构包埋材料

Preparation and characterization of Pd-Ag alloy composite membrane with magnetron sputtering

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Science China Chemistry 1999年第6期42卷 581-588页

作者：赵宏宾熊国兴 N.Stroh H.Brunner fraunhofer institute of Interfacial Engineering and Biotechnology Nobelstrasse 12 D-70569 Stuttgart Germany Germany

A Pd-Ag (24 wt%) alloy composite membrane was prepared by the magnetron sputtering. A γ-A1203 membrane was synthesized by the sol-gel method and used as substrate of the Pd-Ag alloy film. The process parameters of the magnetron sputtering were optimized as a function of the compactness of the Pd-Ag alloy film. The best membrane with a thickness of 1 μm was produced with a sputtering pressure of 2.7 Pa and a substrate temperature of 400°C. The membrane had an H2/N2 permselectivity of 51.5-1000 and an H, permeation rate of 0.036-1.17 x 10-5cm3/cm2.s. Pa, depending on operating conditions.

关键词： Pd-Ag membrane A1203 membrane sol-gel sputtering H2 separation

Experimental and numerical investigation on alternatives to sandy gravel

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Defence Technology（防务技术） 2024年第1期31卷 130-141页

作者： V.Denefeld H.Aurich fraunhofer institute for High-Speed Dynamics Ernst-Mach-Institut(EMI)Ernst-Zermelo-Str.479104FreiburgGermany fraunhofer institute for High-Speed Dynamics Ernst-Mach-Institut(EMI)Am Christianswuhr 279400KandernGermany

The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored *** Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy *** use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and *** paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water *** impulses are measured with a ring technology developed at the fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation *** results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.

关键词： Improvised explosive device(IED) Specific impulse Momentum transfer Sandy gravel Glass spheres Numerical model Soil moisture

Adaptive progressive download based on the MPEG-4 file format

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第z1期7卷 106-111页

作者： FRBER Nikolaus DHLA Stefan ISSING Jochen Multimedia Transport Dept.Audio Fraunhofer Institute for Integrated Circuits IISErlangen 91058Germany

In this paper we describe how progressive download and adaptive streaming can be combined into a simple and efficient streaming framework. Based on the MPEG-4 file format (MP4) we use HTTP for transport and argue that these two components are sufficient for specifying an open streaming architecture. The client selects appropriate chunks from the MP4 file to be transferred based on (1) the header information (i.e. the 'moov' box) in the first part of the file and (2) his observation of network throughput. The framework is completely client driven which allows for better server scalability and reduces signalling overhead. We discuss architecture and implementation issues such as complexity, interoperability and scalability and compare to 3GPP PSS Re1-6 adaptive streaming when appropriate. Measurements from a simple MP4/HTTP streaming client are presented showing that appropriate chunks are selected such that increased reliability is achieved.

关键词： HTTP-streaming Adaptive progressive download MPEG-4 file format (MP4) Moov box

Structural Characterization of Laser Bonded Sapphire Wafers Using a Titanium Absorber Thin Film

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Journal of Materials Science & Technology 2015年第5期31卷 484-488页

作者： A.de Pablos-Martín S.Tismer Th.Hche fraunhofer institute for Mechanics of Materials IWM Walter-Hlse-Str.106120 HalleGermany

Two sapphire substrates were tightly bonded by irradiation with a 1064 nm nanosecond laser and using a sputtered 50 nm-titanium thin film as an absorbing *** laser irradiation,aluminum from the upper substrate is incorporated into the thin film,forming Ti-Al-O *** the irradiated region becomes transparent,the bond quality was evaluated by scanning acoustic microscopy.

关键词： Laser welding Absorbing film Sapphire wafer bondin

Manufacturing of Long Products Made of Innovative Lightweight Materials

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Acta Metallurgica Sinica(English Letters) 2015年第12期28卷 1496-1502页

作者： Karsten Richter Roland Müller Andreas Kunke Verena Kr? usel Dirk Landgrebe fraunhofer institute for Machine Tools and Forming Technology (IWU) Professorship Forming and Joining (UFF) Technische Universit?t Chemnitz

The processing of innovative lightweight materials to sheet metal components and assemblies with globally or locally defined properties is the object of this work. It takes a load-dependent design of components and assemblies, for example, based on the composition of different construction materials or a targeted setting of component areas with specified characteristics to fully exploit the lightweight potential when substituting conventionally used materials. Different process chains for the manufacturing of roll-formed long products made of magnesium alloys and high-strength steels with locally defined properties will be presented in this paper. Depending on the kind of material to be formed and the desired product characteristics, different temperature managements are needed for capable processes. Due to limited formability at room temperature, magnesium alloys require a heating of the forming zones above 200–225 °C throughout the bending process in order to activate additional gliding planes and to avoid any failures in the radii. The realization of local hardening effects requires at least one process-integrated heat treatment when roll forming manganese–boron steels. For both processes, it is imperative to realize a heating and cooling down or quenching appropriate for the manufacturing of long products with the required quality. Additionally, proper line speeds that allow a continuously operated economical production have to be considered. Research results including design, FEA, realization and experimentation of the mentioned process chains and strategies will be described in detail.

关键词： Roll forming Heat treatment Lightweight component Light metals Manganese steels AZ31 magnesium alloy

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

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Optoelectronics Letters 2008年第2期4卷 140-142页

作者： Robert Schmitt Tilo Pfeifer Frank Depiereux Niels Knig fraunhofer institute for Production Technology (IPT) Steinbachstrasse 17 52074 Aachen Germany

Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.

关键词：纤维光干扰术光检测技术测量方法