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Attritor-milling of poly(amide imide) suspensions

Particuology 2014年第6期12卷 92-96页

作者： M.F.H.Wolff s.antonyuk s.Heinrich G.A.schneider Hamburg University of Technology Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology Institute of Advanced Ceramics

The milling behavior of poly(amide imide),which serves as a prototypical hydrophilic high-performance polymer with a high glass transition temperature,was investigated.Various milling conditions(milling times up to 7h,stirrer tip speeds of 3.4-4.9 m/s,and mass concentrations of 5-20%) were tested,and particle sizes as low as d50,33μm were obtained.The milling was performed at 11℃ in an attritor.Differential scanning calorimetry and thermogravimetric analysis were performed before and after milling to investigate the effect of milling on the glass transition temperature and on the decomposition behavior of the polymer.The suspension obtained after milling was observed to be stable without the addition of stabilizers or the adjustment of the pH value,and no negative effect of milling on the polymer properties was observed.The attritor technique proved to be an adequate and efficient milling tool for the production of micrometer-sized high-performance polymer suspensions.

关键词： Attritor Polymer Grinding suspension

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Coefficient of restitution for particles impacting on wet surfaces： An improved experimental approach

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Particuology 2016年第2期14卷 1-9页

作者： B. Cunger V. salikov s. Heinrich s. antonyuk V.s. sutkar N.G. Deen J.A.M. Kuipers Institute of solids Process Engineering and Particle Technology Hamburg University of Technology Denickestrasse 15 21073 Hamburg Germany Particle Process Engineering Department of Mechanical and Process Engineering University ofKaiserslautern Cottlieb-Daimler-Strasse 67663 Kaiserslautern Germany Multiphase Reactors Group Department of Chemical Engineering and Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB EindhovenThe Netherlands

The coefficient of restitution is widely used to characterize the energy dissipation rate in numerical simulations involving particle collisions. The challenge in measuring the coefficient of restitution is the strong scatter seen in experimental data that results from varying particle properties, i.e. shape and surface roughness, and from imperfections in the experimental technique. To minimize this scattering, a novel experimental setup was developed based on two synchronized high-speed cameras capturing the collision behaviour of a particle in three dimensions. To measure the wet restitution coefficient, which describes particle impact in the presence of a liquid layer in the contact region, additional accuracy can be achieved by measuring the liquid layer thickness by a high-precision optical confocal sensor. The coefficient of restitution was measured for glass particles with two different diameters, at different relative velocities and liquid layer thicknesses, with a focus on small collision velocities and thin liquid layers, using both the improved （three dimensional） and the conventional （two dimensional） approaches to quantify the improvement of the new method＇s accuracy.

关键词： Particle impact Coefficient of restitution Liquid layer Improved experimental setup

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Microstructuring of titanium surfaces with plasma-modified titanium particles by cold spraying

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Particuology 2019年第3期17卷 90-104页

作者： P. Breuninger F. Krull s. Buhl A. Binder R. Merz M. Kopnarski B. sachweh s. antonyuk Technische Universitat Kaiserslautern Institute of Particle Process Engineering Kaiserslautern Germany BAsFsE Ludwigshafen Germany IFOs GmbH Institute for Surface and Thin Film Analysis GmbH Kaiserslautern Germany

Although the deposition mechanisms of the cold spray process are well studied, few reports regarding the use of surface-modified particles exist. Herein, titanium particles 3-39 μm in size and with an angular shape were modified in a plasma-enhanced chemical vapor deposition process in Ar, Ar-C2H2, and N2 plasmas. After Ar-C2H2 and N2 treatments, the respective presence of TiC and TiN on the particle surface was confirmed via transmission electron microscopy and energy-dispersive X-ray, X-ray photoelectron, and Raman spectroscopies. The powders were deposited on titanium substrates by cold spray experiments, where unmodified particles up to 10(xm in size exhibited a successful surface bon ding. This finding was described by an existing analytical model, whose parameters were achieved by computational fluid dynamics simulations taking the particle shape factor into account:. A good deposition of plasma-modified particles up to 30 μm in size was experimentally observed, exhibiting an upper size limit larger than that predicted by the model. Higher surface roughness values were found for plasmamodified particles, as determined by 3D scanning electron microscopy. The water contact angle indicated that argon treatment influenced the wettability. Tribological tests showed a decrease of the initial friction coefficient from 0.53 to 0.47 by microstructuring.

关键词： Chemical vapor deposition Cold spray surface modification Computational fluid dynamics

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surface structuring of case hardened chain pins by cold-sprayed microparticles to modify friction and wear properties

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Particuology 2015年第4期13卷 32-40页

作者： s. Buhl K. schmidt D. sappok R. Merz C. Godard E. Kerscher M. Kopnarski B. sauer s. antonyuk s. Ripperger Particle and Process Engineering University ofKaiserslautern Gottlieb-Daimler-Strafle 47 Kaiserslautern Germany Institute of Machine Elements Gears and Transmissions University ofgaiserslautern Gottlieb-Daimler-Strafge 42 Kaiserslautern Germany Materials Testing Gottlieb-Daimler-Strαβe 47 Kaiserslautern Germany IFOs Insn'tute Trippstadter Strafge 120 Kaiserslautern. Germany

This paper presents the results of the application of a cold spray technique for structuring metallic surfaces with microparticles. The resulting changes in surface properties were characterized to observe their influences on the tribological behavior of the structured surface. The spray technique was applied to a technical component, a 16MnCr5 steel chain pin, designed to be mounted in a linear reciprocating tribometer. TiO2 microparticles were used to structure the surface with a homogeneous distribution of singly dispersed particles, rather than a homogeneous closed coating on the surface. Tribometer tests were performed to directly compare structured and unstructured chain pins, and a significantly reduced sliding friction coefficient was observed for the structured pin. The pins were characterized in detail by surface analysis prior to and after application of the tribological load to set the surface parameters and surface chemistry, even on the microscale. It was confirmed that the particle structuring induced changes in the surface properties, and the durability of the changes after tribological loading was evaluated.

关键词： Cold spraying surface structuring TiO2 microparticles Driving chain sliding friction

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Influence of liquid layers on energy absorption during particle impact

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Particuology 2009年第4期7卷 245-259页

作者： sergiy antonyuk stefan Heinrich Niels Deen Hans Kuipers Hamburg University of Technology Institute of Solids Process Engineering and Particle Technology Denickestr. 15 21071 Hamburg Germany University of Twente Fundamentals of Chemical Reaction Engineering Faculty of Science and Technology PO Box 217 Enschede 7500 AE The Netherlands

The influence of the thickness of a covering liquid layer and its viscosity as well as the impact velocity on energy loss during the normal impact on a flat steel wall of spherical granules with a liquid layer was studied. Free-fall experiments were performed to obtain the restitution coefficient of elastic-plastic γ- Al2O3 granules by impact on the liquid layer, using aqueous solutions of hydroxypropyl methylcellulose with different concentrations for variation of viscosity （1-300 mPa s）, In the presence of a liquid layer, increase of liquid viscosity decreases the restitution coefficient and the minimum thickness of the liquid layer at which the granule sticks to the wall. The measured restitution coefficients were compared with experiments performed without liquid layer. In contrast to the dry restitution coefficient, due to viscous losses at lower impact velocity, higher energy dissipation was obtained, A rational explanation for the effects obtained was given by results of numerically solved force and energy balances for a granule impact on a liquid layer on the wall. The model takes into account forces acting on the granule including viscous, surface tension, capillary, contact, drag, buoyancy and gravitational forces. Good agreement between simulations and experiments has been achieved.

关键词： Granule impact Restitution coefficient Energy dissipation Liquid layer Liquid bridge

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