bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metal dusting behaviour of welded Ni‐base alloys with different surface finish
Authors: Grabke H. J. , Müller‐Lorenz E. M. , Zinke M. 
Published: October 2003

AbstractWelded Ni‐base alloys and Alloy 800 were exposed under metal dusting conditions at 600°C and 650°C for up to 6000 hours. Alloy 800 was attacked very strongly already in the first days and Alloy 600 also rather soon and widespread, on both materials attack started mainly in the heat affected zone. Several surface states of Alloy 600: brushed, ground, sand‐blasted and pickled were tried only grinding caused a modest delay and decrease of metal dusting attack. Generally the attack was less widespread but deeper at 650°C than at 600°C, also for Alloy 601 and 602. The latter alloys show minor, mainly local attack, but especially the welds are affected. TIG welding led to better resistance than hand‐welding.
Effect of H2S on metal dusting of iron
Authors: Schneider A. , Grabke H. J. 
Published: October 2003

AbstractA review is given on the effect of H2S on metal dusting of iron which has been studied by gas carburisation in CO‐H2‐H2O‐H2S and CH4‐H2‐H2S mixtures at 500 and 700°C.The presence of H2S in carburising gas atmospheres leads to sulphur adsorption on the iron surface, which retards carbon transfer. Segregation experiments and surface analyses have shown that sulphur segregates (and thus adsorbs) on cementite surfaces as well as on iron surfaces. The adsorbed sulphur also suppresses graphite nucleation and thus can stop the reaction sequence of metal dusting.Experiments by thermogravimetric analysis (TGA) have shown that the extent of retardation of metal dusting depends on temperature, carbon activity and H2S content. The higher the carbon activity, the higher is the H2S content required for suppression of metal dusting.At carbon activities aC > aC(Fe/Fe3C) the metastable iron carbide, cementite (Fe3C), occurs as an intermediate phase during metal dusting. Carburisation experiments in CO‐H2‐H2O‐H2S mixtures at 500°C and X‐ray diffraction analysis (XRD) of carburised samples have revealed that at very high carbon activities a second iron carbide, Hägg carbide (Fe5C2), forms on the cementite surface. Microstructural investigations have shown that both metastable carbides decompose during metal dusting.Metal dusting experiments on iron at 700°C have been performed in CH4‐H2‐H2S gas mixtures. By adding 15 ppm H2S to the CH4‐H2 atmosphere the onset of metal dusting can be retarded for more than 350 hours. By means of Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDX) it was shown that coke contains graphite, cementite and iron particles with adsorbed sulphur.
Mechanisms and driving forces of metal dusting
Authors: Szakálos P. 
Published: October 2003

AbstractThe mechanisms of metal dusting as it appears on different ferritic stainless steels and pure iron have been described in detail. A mechanism for metal dusting (MD) of chromia‐forming as well as alumina‐forming steels is proposed, based on results from laboratory exposures of 26Cr‐steel and FeCrAl‐alloy at 600–650°C for up to 5000 h in a synthesis gas low in water vapour, 25%CO + 3%H2O + H2. Metallographical examinations, FEG‐SEM, SEM‐EDX analysis and X‐ray diffraction, as well as thermodynamic calculations were made in order to identify and describe the different metal dusting processes. The work focuses on the role of carbides and oxides to explain the observations and give a description of the metal dusting phenomenon as it appears in engineering alloys. This mechanism was first observed and identified in a study of an austenitic stainless steel.The driving force for steady state MD on pure iron and low alloyed steels is described and a secondary MD‐mechanism, carbon nanotube formation, is described in detail. With these additional results it is now possible to extend understanding of the MD‐processes to a wide range of engineering alloys.
Occurrence of metal dusting – referring to failure cases
Authors: Grabke H. J. , Spiegel M. 
Published: October 2003

AbstractTwelve years of research on metal dusting at the Max‐Planck‐Institut for Iron Research have led to comprehensive knowledge on the mechanisms and kinetics of metal dusting and on ways and means for prevention of this corrosion phenomenon, – this knowledge is shortly summarized in this paper.Inspite of this state of understanding, the present opinion in industry is that metal dusting is mysterious and not predictable and cannot be controlled. This paper is intended to show that the occurrence of metal dusting and its reasons can be well understood, by describing and explaining five failure cases.
Coke formation during metal dusting of iron in CO‐H2‐H2O gas with high CO content
Authors: Zhang J. , Schneider A. , Inden G. 
Published: October 2003

AbstractIron carburisation and coke formation during metal dusting of iron have been investigated in the gas mixture of 75%CO‐24.8%H2‐0.2%H2O at 600°C and 700°C. In all cases, cementite is formed at the surface, together with a coke layer on the top. In the coke layer, two morphologies of graphite are identified: compact bulk graphite with a uniform thickness and a columnar structure, and filamentous carbon with iron‐containing phases at the tip or along its length. The examination of coke formation in different stages of reaction at 700°C reveals that the coke contains two layers. The inner layer is composed of filaments, while the outer layer consists of the compact columnar graphite. After 2 h reaction the top compact graphite layer has suffered a serious deformation and has formed fractures because of the growth of catalytic filamentous carbon underneath. These filaments grow outside from these fractures and finally cover the whole surface after 4 h reaction. At 600°C, however, the coke contains a thick bulk graphite layer and non‐uniformly distributed filaments on the top. The bulk graphite layer is composed of many graphite columns which are loosely piled and are vertical to the surface. Each graphite column consists of many fine graphite fibres in parallel with the columnar axis. Filaments grow outside preferably from the gaps among these graphite columns and along the grinding scratches. TEM analysis of the coke detects very convoluted filaments with iron‐containing particles at the tip or along their length. XRD and TEM analyses show that these particles are Fe3C rather than metallic iron.
Synthesis and Characterization of α,ω‐Telechelic Polymers by Atom Transfer Radical Polymerization and Coupling Processes
Authors: Yurteri Seda , Cianga Ioan , Yagci Yusuf 
Published: October 2003

AbstractInitiators for atom transfer radical polymerization (ATRP) bearing different functional groups (aldehyde, aromatic hydroxyl, dimethyl amino) were synthesized and characterized. Monotelechelics with low molecular weight were obtained by ATRP of styrene using these initiators in the presence of the CuBr/bpy catalytic complex. α,ω‐Telechelic polymers with double molecular weights with respect to the starting materials were prepared by coupling of monotelechelics under atom transfer radical generation conditions, in the absence of monomer, using CuBr as catalyst, tris[2‐(dimethylamino)ethyl]amine (Me6TREN) as a ligand, under Cu0 mediated reductive conditions and with toluene as solvent. Terminal Br atoms present in monotelechelic polystyrenes (PS) as a consequence of the ATRP mechanism also offer other routes for preparing telechelic polymers. Aldehyde functionalized polymer was etherified with hydroquinone furnishing telechelic PS with a molecular weight that was two times higher. All polymers were characterized by spectral methods (NMR, IR spectroscopy) as well as by GPC.Synthesis of initiators for atom transfer radical polymerization bearing different functional groups, for example, aldehyde, aromatic hydroxyl, dimethyl amino.magnified imageSynthesis of initiators for atom transfer radical polymerization bearing different functional groups, for example, aldehyde, aromatic hydroxyl, dimethyl amino.
Structure and Phase Transitions of Poly(heptamethylene p,p′‐bibenzoate): Time‐Resolved Synchrotron WAXS and DSC Studies
Authors: Pérez Ernesto , Todorova Ginka , Krasteva Mania , Pereña José M. , Bello Antonio , Marugán Mónica M. , Shlouf Miroslav 
Published: October 2003

AbstractTime‐resolved wide‐angle X‐ray scattering (WAXS), as well as differential scanning calorimetry (DSC) and polarisation microscopy studies, were applied to investigate the structure and phase transitions of poly(heptamethylene p,p′‐bibenzoate). Temperature dependencies of several structural parameters were determined. Complete transformation from an isotropic melt to a smectic phase was suggested whereas the transition from a smectic to crystalline phase is only partial (around 30%), although it takes place from the ordered SCA phase. Crystals are formed within the SCA domains with nearly the same coherent length. On the basis of the analysis of the position and the profile of the diffuse wide‐angle X‐ray scattering and mesogenic layer spacing, it was assumed that either crystallisation modifies the smectic structure, or mesophase losses its positional order because of the lack of mobility of the spacers at low temperatures.WAXS scattering profiles corresponding to P7MB: a) cooling from the isotropic melt at 2 °C · min−1; b) subsequent melting at 12 °C · min−1.magnified imageWAXS scattering profiles corresponding to P7MB: a) cooling from the isotropic melt at 2 °C · min−1; b) subsequent melting at 12 °C · min−1.
13C NMR Study of Copolymers of Propene with Higher 1‐Olefins with New Microstructures by ansa‐Zirconocene Catalysts
Authors: Wahner Udo M. , Tincul Ioan , Joubert Dawid J. , Sadiku Emmanuel R. , Forlini Fabrizio , Losio Simona , Tritto Incoronata , Sacchi Maria Carmela 
Published: October 2003

AbstractCopolymers of propene and higher 1‐olefins (1‐butene, 1‐pentene, 1‐hexene, 1‐heptene, 1‐octene, and 4‐methyl‐1‐pentene (4M1P)), prepared with rac‐Et(Ind)2ZrCl2 (EI) and rac‐Me2Si(2‐MeBenz‐[e]Ind)2ZrCl2 (MBI), were comprehensively analyzed by 13C NMR spectroscopy. These catalysts known to produce isotactic polypropene lead to two vastly different families of copolymers under the chosen experimental conditions. All copolymers produced with EI possessed comparable isotacticities as well as similar stereosequences. Furthermore, these copolymers did not significantly differ from those of the reference propene homopolymer. However, the copolymers produced with MBI significantly differed both from the reference propene homopolymer and among themselves. In fact, in contrast to the corresponding highly isotactic homopolymer, the whole series of copolymers was characterized by rather low isotacticities. The degree of tacticity was strongly influenced by the comonomer type. A detailed 13C NMR analysis revealed that these copolymers are constituted by highly isotactic sequences and by atactic sequences of various lengths. It is proposed that the formation of atactic sequences is triggered by the insertion of a comonomer. It seems likely that MBI can shift from a stereoselective to a non‐stereoselective state due to an interaction with higher linear or branched comonomer.13C NMR spectra of propene/1‐pentene (a) and propene/4‐methyl‐1‐pentene (b) prepared with MBI.magnified image13C NMR spectra of propene/1‐pentene (a) and propene/4‐methyl‐1‐pentene (b) prepared with MBI.
Thermosensitive Hollow Capsules Based on Thermoresponsive Polyelectrolytes
Authors: Glinel Karine , Sukhorukov Gleb B. , Möhwald Helmuth , Khrenov Victor , Tauer Klaus 
Published: October 2003

AbstractThermosensitive hollow capsules were successfully fabricated by the layer‐by‐layer deposition onto colloid particles of oppositely charged diblock copolymers each containing a poly(N‐isoproprylacrylamide) (PNIPAM) block and by the subsequent decomposition of the core. The multilayer growth was characterized by electrophoresis and single particle light scattering. By combining confocal microscopy observation and FRAP measurements, we showed that the morphology and the permeability of the capsules change upon heating in aqueous solution. The decrease of size accompanied by a decrease of the permeability with increasing temperature was attributed to structural rearrangements in the shell. However, this process is only partially reversible upon cooling, limiting the thermoresponsive behavior of the capsules.CLSM images of hollow capsules in presence of 6‐carboxyfluorescein (left) and fluorescein‐labeled dextran (right).magnified imageCLSM images of hollow capsules in presence of 6‐carboxyfluorescein (left) and fluorescein‐labeled dextran (right).
Formation of Macrocycles in the Synthesis of Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl)
Authors: Ostrauskaite Jolita , Strohriegl Peter 
Published: October 2003

AbstractA series of polymerizations of 3,6‐dibromo‐9‐(2‐ethylhexyl)carbazole was carried out in different monomer concentrations using standard Yamamoto reaction conditions. It was found that the molecular weight of the resulting poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) strongly depends on the monomer concentration in the reaction mixture. Matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) measurements confirmed the formation of low‐molar‐mass cyclic oligomers of the 3,6‐disubstituted carbazole. In this paper we describe, for the first time, the formation of large amounts of a cyclic tetramer and of higher macrocycles in the synthesis of poly(N‐alkyl‐3,6‐carbazoles) by the Yamamoto method. This seems to be a limiting factor in the synthesis of high molecular weight poly(N‐alkyl‐3,6‐carbazole)s. The optical, thermal, and electrochemical properties of poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) have been investigated. Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) is thermally stable, with 5% weight loss at 460 °C in nitrogen. The polymer exhibits a weak blue fluorescence with a maximum at 425 nm. Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) is electrochemically stable, its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are −5.0 and −1.6 eV, respectively.magnified image
Use of Hydroxyl Functionalized (Meth)acrylic Cross‐Linked Polymer Microparticles as Chain Transfer Agent in Cationic Photopolymerization of Cycloaliphatic Epoxy Monomer, 2
Authors: Valette Ludovic , Pascault Jean‐Pierre , Magny Benoît 
Published: October 2003

AbstractThis study is related to the use of hydroxyl functional acrylic cross‐linked polymer microparticles (CPM, also named microgels) as a chain transfer agent in cationic photopolymerization of cycloaliphatic epoxy monomer. All CPM were based on butyl acrylate and were consequently rubbery at ambient temperature. The effect of the stabilizing acrylate monomer used during the CPM synthesis was evaluated with respect to the viscoelastic properties of the photopolymerized cationic‐type epoxy films. The viscoelastic properties were correlated to the photopolymerized film morphology observed by transmission electron microscopy. Two acrylate monomers used as stabilizing agents during CPM synthesis were compared: cardura acrylate (CA) and lauryl acrylate (LA). CA was a good stabilizer for CPM in epoxy monomer before photocure and the CPM were well dispersed into the network after reaction. In contrast, LA was a poor stabilizer resulting in large CPM aggregation. The blend of these two types of CPM led to intermediate morphology, probably because of the flocculation of the CPM stabilized with LA. Conversely, CPM synthesized with a blend of the two stabilizing acrylate monomers induced in epoxy matrix a specific bi‐continuous morphology and consequently unique viscoelastic properties.TEM micrographs of a photopolymerized film with 15 wt.‐% CPM(BA + 20%HEA)‐20%CA + 15% CPM(BA + 18%HEA)‐27%LA used as chain transfer agents.magnified imageTEM micrographs of a photopolymerized film with 15 wt.‐% CPM(BA + 20%HEA)‐20%CA + 15% CPM(BA + 18%HEA)‐27%LA used as chain transfer agents.
Laccases to Improve the Whiteness in a Conventional Bleaching of Cotton
Authors: Tzanov Tzanko , Basto Carlos , Gübitz Georg M. , Cavaco‐Paulo Artur 
Published: October 2003

AbstractThis study reports for the first time on the enhancement of the bleaching effect achieved on cotton using laccase enzyme. Laccases applied in short‐time batchwise or pad‐dry processes prior to conventional peroxide bleaching, improved the end fabric whiteness. The whiteness level reached in the combined enzymatic/peroxide process was comparable to the whiteness in two consecutive peroxide bleaches.Effect of 10 min laccase pre‐treatment at 60 °C, pH 5 on fabrics whiteness before and after a conventional hydrogen peroxide bleaching.magnified imageEffect of 10 min laccase pre‐treatment at 60 °C, pH 5 on fabrics whiteness before and after a conventional hydrogen peroxide bleaching.
Dry phosphorus silicate glass etching for multicrystalline silicon solar cells
Authors: Nositschka W. A. , Voigt O. , Kenanoglu A. , Borchert D. , Kurz H. 
Published: October 2003

AbstractA dry plasma etching process for phosphorus silicate glass (PSG) in a SiN‐PECVD batch reactor is developed. In the same reactor PSG etching and anti‐reflective coating (ARC) can be performed successively. To demonstrate industrial feasibility, screen‐printed solar cells are manufactured and compared with cells prepared by a standard wet chemical process. Copyright © 2003 John Wiley & Sons, Ltd.
High‐efficiency copper indium gallium diselenide (CIGS) solar cells with indium sulfide buffer layers deposited by atomic layer chemical vapor deposition (ALCVD)
Authors: Naghavi N. , Spiering S. , Powalla M. , Cavana B. , Lincot D. 
Published: October 2003

AbstractThis paper presents optimization studies on the formation of indium sulfide buffer layers for high‐efficiency copper indium gallium diselenide (CIGS) thin‐film solar cells with atomic layer chemical vapour deposition (ALCVD) from separate pulses of indium acetylacetonate and hydrogen sulfide. A parametric study of the effect of deposition temperature between 160° and 260°C and thickness (15–30 nm) shows an optimal value at about 220°C for a layer thickness of 30 nm, leading to an efficiency of 16·4%. Analysis of the device shows that indium sulfide layers are characterised by an improvement of the blue response of the cells compared with a standard CdS‐processed cell, due to a high apparent band gap (2·7–2·8 eV), higher open‐circuit voltages (up to 665 mV) and fill factor (78%). This denotes high interface quality. Atomic diffusion processes of sodium and copper in the buffer layer are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Supramolecular polymers formed by cinnamoyl cyclodextrins
Authors: Harada Akira , Miyauchi Masahiko , Hoshino Taiki 
Published: October 2003

Abstract6‐Cinnamoyl α‐cyclodextrin (6‐CiO‐α‐CD) and 6‐cinnamoyl β‐cyclodextrin (6‐CiO‐β‐CD) were prepared. 6‐CiO‐α‐CD formed intermolecular complexes to give supramolecular oligomers. 6‐CiO‐β‐CD formed insoluble supramolecular complexes in the solid state. The structures of these complexes are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3519–3523, 2003
Nanostructured ion‐conductive films: Layered assembly of a side‐chain liquid‐crystalline polymer with an imidazolium ionic moiety
Authors: Hoshino Koji , Yoshio Masafumi , Mukai Tomohiro , Kishimoto Kenji , Ohno Hiroyuki , Kato Takashi 
Published: October 2003

AbstractAn ion‐conductive mesogenic monomer with an imidazolium ionic moiety has been designed to obtain self‐assembled materials forming ionic layers. Self‐standing polymer films are prepared by in situ photopolymerization of the monomer that forms homeotropic monodomain on a normal glass substrate in the smectic A phase. Macroscopically oriented, layered nanostructures are formed in the film. The ionic conductivity parallel to the smectic layer has been measured for the oriented film. In the smectic A phase at 150 °C, the magnitude of conductivity is about 10−2 S cm−1. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3486–3492, 2003
Electric properties of self‐assembled monolayers of helical peptides by scanning tunneling spectroscopy
Authors: Kitagawa Kazuya , Morita Tomoyuki , Kawasaki Megumi , Kimura Shunsaku 
Published: October 2003

AbstractHelical peptides having a disulfide group at one terminal, Lipo‐(Leu‐Aib)12‐OBzl (Lipo and OBzl represent lipoic acid and benzyl ester, respectively, SSL24B), and Boc‐NHCH2CH2NHCO‐Fc‐CO‐Ala‐(Leu‐Aib)8‐lipoamide (Boc, Fc, and lipoamide represent t‐butyloxycarbonyl, ferrocene, and lipoamine, respectively, FcL16SS), were synthesized, and self‐assembled monolayers (SAMs) of the helical peptides were prepared on gold. When the SSL24B SAM was observed at high‐bias voltage by scanning tunneling microscopy (STM) under ultrahigh vacuum, bright spots with higher conductivity appeared in the STM image. The image was restored again to a homogeneous surface with lower bias voltage, suggesting that Au–S linkage should be reversibly changed to a conductive state. The current/voltage (I‐V) curve by scanning tunneling spectroscopy (STS) at the bright domains demonstrated a rectification behavior where current increases drastically at a positive bias voltage above 3.0 V. However, the I‐V curve of the FcL16SS SAM showed a current increase at negative bias voltage below −1.5 V. The redox group is, thus, a determining factor for the direction of this flow. However, STS at low‐bias voltage and with the tip being inserted in the peptide SAM revealed a zero‐conductance region in the I‐V curve. The peptide layer may act as a molecular capacitor because of a large dielectric constant of the helical peptide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3493–3500, 2003
Synthesis and self‐organization of rod–dendron and dendron–rod–dendron molecules
Authors: Lecommandoux Sébastien , Klok Harm‐Anton , Sayar Mehmet , Stupp Samuel I. 
Published: October 2003

AbstractWe synthesized molecules containing one or two dendritic segments and a rigid‐rod‐like segment with their structures in the solid state. The molecules with rod–dendron or dendron–rod–dendron architecture had biphenyl ester rigid segments and 3,4,5 tris(n‐dodecyloxy)benzoate of first or second generation as their dendritic segments. The variables investigated included the rod segment length as well as dendron generation, and all materials obtained were characterized by optical microscopy, differential scanning calorimetry, and X‐ray scattering. Depending on the size of the rod segment and generation number of the dendritic segment, molecules organized into smectic, columnar, or cubic phases, and the symmetries observed were dominated by the anisotropic rod–rod interactions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3501–3518, 2003
Aminosalicylate‐based biodegradable polymers: Syntheses and in vitro characterization of poly(anhydride‐ester)s and poly(anhydride‐amide)s
Authors: Anastasiou Theodore J. , Uhrich Kathryn E. 
Published: October 2003

AbstractPoly(anhydride‐ester)s and poly(anhydride‐amide)s derived from both 4‐ and 5‐aminosalicylate acids (4‐ and 5‐ASA) were synthesized and characterized by physicochemical methods. Thermal and solubility characteristics directly correlated to the polymer backbone composition; polymers based on 5‐ASA had greater solubilities in organic solvents than polymers based on 4‐ASA, and the poly(anhydride‐ester)s thermally decomposed at temperatures nearly 100 °C higher than the corresponding poly(anhydride‐amide)s. The polymers were self‐contained, controlled‐release systems that combine the drug and controlled‐release mechanism into the polymer backbone. The erosion and degradation characteristics of the polymers were measured in physiologically relevant media. All polymer matrices fully degraded in media buffered to pH 7.4, whereas in acidic media (pH 1.2), all polymer matrices maintained greater than 50% mass over a 90‐day time period. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3667–3679, 2003