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ANTIOXIDANT DEPLETION AND OIT VALUES OF HIGH IMPACT PP STRANDS

Chinese Journal of Polymer Science 2009年第3期27卷 435-445页

作者： Werner W.Müller Ines Jakob Chunshan Li Renate Tatzky-Gerth federal institute for materials research and testing(bam) D-12200 BerlinGermany

The service life of a polyolefin product depends to large extent on the type and amount of the antioxidants added. During the manufacturing,storage and use of the product the antioxidants are depleted by physical processes and chemical degradation,and this impairs its long-term *** initial and in-use oxidation stability is often characterized and monitored by the measurement of the oxidative induction time(OIT),and service life predictions are based on the rate of decrease of the OIT *** study the correlation between the OIT value and the actual antioxidant concentration,eight random arrays of high-impact polypropylene(PP)strands stabilized using six different antioxidant packages(composed of Irgafos 168,Irganox 1010 and 1330,Chimassorb 944)were immersed in hot water(80℃and 90℃)and oven aged in air (80℃)for more than two years,and the change of OIT values and antioxidant concentrations was *** phosphitic and phenolic stabilizers water immersion is generally a more critical aging condition than oven aging in air,while for the hindered amine stabilizers(HAS)the opposite was *** expected,a linear correlation between OIT values and concentrations was found for the'classical'package of phosphitic and phenolic *** the case of Irganox 1330,the change of the OIT values during aging was considerably slower than the change of *** when zero concentration was reached according to the vanishing peak height in the chromatogram,a considerable OIT value was still *** may be due to unidentified degradation products of Irganox 1330 which still act as antioxidants in the long *** of HAS(Chimassorb 944)seems to enhance the initial OIT of stabilized phenolic samples and the long-term effectiveness of the phenolic stabilization under air oven aging ***,the marked long-term effectiveness of the HAS itself and the slow change with time of the concentration were not detectable by OIT measurements

关键词： Polypropylene Stabilizers Oxidative resistance Antioxidant depletion Oxidative induction time

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Simulation of welding

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Frontiers of materials Science 2011年第2期5卷 77-78页

作者： Chuan-Song WU Michael RETHMEIER Christopher SCHWENK institute of materials Joining Shandong University Jinan China federal institute for materials research and testing （bam） Berlin Germany

Welding has become the most important materials processing technology in manufacturing, and has critical effects on the quality, reliability and life of products as well as production cost, efficiency and response speed to market. As various kinds of high performance metallic materials are widely used in engineering, there are more demands in manufacturing industry for advanced welding technology.

关键词： manufacturing theory-experiment-production Science Promotion

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Thermochemical Treatment——Technologies for Recovery and Utilisation of materials

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过程工程学报 2006年第2期6卷 231-236页

作者： Gerd Kley Rudolf Brenneis Burkart Adamczyk Franz-Georg Simon Division Waste Treatment and Remedial Eng. Federal Inst. Materials Research and Testing BAM Berlin 12200 Germany

The arc furnace technology is an ideally suited process for the treatment of hazardous and problematic waste. The operation conditions of the furnace can be adapted for optimal transformation of the waste material input into raw materials and usable products. The process can significantly reduce the impact of contaminated wastes and industrial residues, and enable material conversion and separation. Thus, the products of the process have various applications. The capability of the process is illustrated with three examples, the treatment of bottom ash and filter ash from waste incineration plants, of stainless steel slags and of chromium-containing residues from the refractory industry.

关键词：热化学处理原料分离耐火材料不锈钢

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Gas separation using porous cement membrane

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Journal of Environmental Sciences 2014年第1期26卷 140-146页

作者： Weiqi Zhang Maria Gaggl Gregor J.G.Gluth Frank Behrendt Berlin institute of Technology Department of Energy Engineering Chair EVUR Chinese research Academy of Environmental Sciences Berlin institute of Technology Chair of Building Materials bam federal institute for materials research and testing Division 7.4 Technology of Construction Materials

Gas separation is a key issue in various industrial fields. Hydrogen has the potential for application in clean fuel technologies. Therefore, the separation and purification of hydrogen is an important research subject. CO2 capture and storage have important roles in ＂green chemistry＂. As an effective clean technology, gas separation using inorganic membranes has attracted much attention in the last several decades. Membrane processes have many applications in the field of gas separation. Cement is one type of inorganic material, with the advantages of a lower cost and a longer lifespan. An experimental setup has been created and improved to measure twenty different cement membranes. The purpose of this work was to investigate the influence of gas molecule properties on the material transport and to explore the influence of operating conditions and membrane composition on separation efficiency. The influences of the above parameters are determined, the best conditions and membrane type are found, it is shown that cementitious material has the ability to separate gas mixtures, and the gas transport mechanism is studied.

关键词： gas separation porous membrane clean fuel cement membrane inorganic membranes

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Attenuation of ground vibrations due to different technical sources

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 337-344页

作者： L.Auersch S.Said federal institute of Material research and testing

The attenuation of technically induced surface waves is studied theoretically and experimentally. In this paper, nineteen measurements of ground vibrations induced by eight different technical sources including road and rail traffic, vibratory and impulsive construction work or pile driving, explosions, hammer impulses and mass drops are described, and it is shown that the technically induced ground vibrations exhibit a power-law attenuation v - r ~ where the exponents q are in the range of 0.5 to 2.0 and depend on the source types. Comparisons performed demonstrate that the measured exponents are considerably higher than theoretically expected. Some potential effects on ground vibration attenuation are theoretically analyzed. The most important effect is due to the material or scattering damping. Each frequency component is attenuated exponentially as exp（-kr）, but for a broad-band excitation, the sum of the exponential laws also yields a power law but with a high exponent. Additional effects are discussed, for example the dispersion of the Rayleigh wave due to soil layering, which yields an additional exponent of 0.5 in cases of impulsive loading.

关键词： wave attenuation environmental vibrations field tests material damping scattering damping Rayleigh wave

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Electromagnetic Control of the Weld Pool Dynamics in Partial Penetration Laser Beam Welding of Aluminium Alloys

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Journal of Iron and Steel research International 2012年第S1期19卷 233-236页

作者： V.Avilov A.Schneider M.Lammers A.Gumenyuk M. Rethmeier bam Federal Institute for Materials Research and Testing12205 BerlinGermany

The main characteristic feature of deep penetration laser beam welding is a large temperature difference between the plasma cavity(keyhole)in the weld pool centre and the melting/solidification *** temperature gradients in the weld pool result in very intensive thermocapillary(Marangoni)*** weld pool surface width becomes very large and ***,an externally applied oscillating magnetic field can stabilize the surface of the *** the present work this technology was used to stabilize the weld pool surface in partial penetration 4.4 kW Nd:YAG laser beam welding of AW-5754 aluminium alloy in PA *** AC magnet was mounted on the laser welding *** oscillating magnetic field was oriented perpendicular to the welding *** was found that the AC magnetic field can drastically reduce the surface roughness of welds.X-ray image analysis shows a drastic reduction of welds *** effect can be explained as a result of electromagnetic rectification of the melt.

关键词： electromagnetically controlled laser beam welding weld pool stabilization porosity prevention

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Fluid Flow Simulation of the Influence of a Steady Magnetic Field on the Weld Pool Dynamics in Deep Penetration Laser Beam Welding of Aluminum

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Journal of Iron and Steel research International 2012年第S1期19卷 467-470页

作者： BACHMANN Marcel AVILOV Vjaceslav GUMENYUK Andrey RETHMEIER Michael bam federal institute for materials research and testing Berlin 12205Germany

A multi-physics numerical model was developed to investigate the influence of a steady magnetic field during partial penetration keyhole laser beam welding of an aluminum plate in fiat ***-dimensional heat transfer, fluid dynamics including phase transition and electromagnetic field partial differential equations were solved with the finite element differential equation solver COMSOL *** magnetic field was aligned perpendicularly to the welding *** main objective of these simulations was to estimate the critical value of the magnetic field needed to suppress convective flows in the weld pool during high-power(up to 20 kW)laser beam welding of aluminum alloys with up to 20 mm deep weld *** reveals that steady magnetic fields with corresponding Hartmann numbers Ha2-104 based on the half-width of the weld pool can effectively suppress convective flows in the weld ***,the typically occurring wineglass-shape of the weld cross section caused by thermo-capillary flow is weakened.

关键词： laser beam welding Lorentz force Marangoni stresses natural convection Hartmann effect

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Simulation of inverse heat conduction problems in fusion welding with extended analytical heat source models

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Frontiers of materials Science 2011年第2期5卷 119-125页

作者： V. A. KARKHIN A. PITTNER C. SCHWENK M. RETHMEIER St. Petersburg State Polytechnical University St. Petersburg 195251 Russia federal institute for materials research and testing （bam） Berlin Germany

The paper presents bounded volume heat sources and the corresponding functional-analytical expressions for the temperature field. The power density distributions considered here are normal, exponential and parabolic. The sources model real heat sources like the welding arc, laser beam, electron beam, etc., the convection in the weld pool as well as the latent heat due to fusion and solidification. The parameters of the heat source models are unknown a priori and have to be evaluated by solving an inverse heat conduction problem. The functional-analytical technique for calculating 3D temperature fields in butt welding is developed. The proposed technique makes it possible to reduce considerably the total time for data input and solution. It is demonstrated with an example of laser beam welding of steel plates.

关键词： laser beam welding volume heat source functional-analytical solution inverse modelling

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Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals

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Nano research 2022年第3期15卷 2362-2373页

作者： Bettina Grauel Christian Würth Christian Homann Lisa Krukewitt Elina Andresen Janina Roik Sebastian Recknagel Markus Haase Ute Resch-Genger federal institute for materials research and testing(bam) Division 1.2 BiophotonicsRichard-Willstaetter-Str.1112489 BerlinGermany federal institute for materials research and testing(bam) Division 1.6 Inorganic Reference MaterialsRichard-Willstaetter-Str.1112489 BerlinGermany institute of Chemistry of New materials Department Biology/ChemistryUniversity OsnabrueckBarbarastr.749076 OsnabrueckGermany Department of Anesthesiology and Intensive Care Medicine University Medical Center RostockSchillingallee 3518057 RostockGermany

Despite considerable advances in synthesizing high-quality core/shell upconversion(UC)nanocrystals(NC;UCNC)and UCNC photophysics,the application of near-infrared(NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence(UCL)of UCNC of small size or thin protecting *** obtain deeper insights into energy transfer and surface quenching processes involving Yb^(3+) and Er^(3+) ions,we examined energy loss processes in differently sized solid core NaYF_(4) nanocrystals doped with either Yb^(3+)(YbNC;20%Yb^(3+))or Er^(3+)(ErNC;2%Er^(3+))and co-doped with Yb^(3+) and Er^(3+)(YbErNC;20%Yb^(3+) and 2%Er^(3+))without a surface protection shell and coated with a thin and a thick NaYF_(4) shell in comparison to single and co-doped bulk *** studies at 375 nm excitation demonstrate back-energy transfer(BET)from the ^(4)G_(11/2) state of Er^(3+) to the ^(2)F_(5/2) state of Yb^(3+),through which the red Er^(3+) ^(4)F_(9/2) state is efficiently *** power density(P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and three-photonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+*** intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC *** provide a three-dimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC.

关键词： upconversion luminescence core/shell nanoparticles dopant concentration lifetime volume effect surface quenching

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Simple and fast prediction of train-induced track forces,ground and building vibrations

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Railway Engineering Science 2020年第3期28卷 232-250页

作者： Lutz Auersch federal institute of materials research and testing D-12200 BerlinGermany

A simple and fast prediction scheme is presented for train-induced ground and building *** models such as(one-dimensional)transfer matrices are used for the vehicle–track–soil interaction and for the building–soil *** wave propagation through layered soils is approximated by a frequency-dependent homogeneous *** prediction is divided into the parts“emission”(excitation by railway traffic),“transmission”(wave propagation through the soil)and“immission”(transfer into a building).The link between the modules is made by the excitation force between emission and transmission,and by the free-field vibration between transmission and *** formula for the simple vehicle–track,soil and building models are given in this *** behaviour of the models is demonstrated by typical examples,including the mitigation of train vibrations by elastic track elements,the low-and high-frequency cut-offs characteristic for layered soils,and the interacting soil,wall and floor resonances of multi-storey *** is shown that the results of the simple prediction models can well represent the behaviour of the more time-consuming detailed models,the finite-element boundary-element models of the track,the wavenumber integrals for the soil and the three-dimensional finite-element models of the *** addition,measurement examples are given for each part of the prediction,confirming that the methods provide reasonable *** the prediction models are fast in calculation,many predictions can be done,for example to assess the environmental effect along a new railway *** simple models have the additional advantage that the user needs to know only a minimum of ***,the prediction is fast and user-friendly,but also theoretically and experimentally well-founded.

关键词： Railway-induced vibration Ground vibration Layered soil Building response Excitation forces Track and vehicle irregularities

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