Institution
DECHEMA
Nonprofit•Frankfurt am Main, Germany•
About: DECHEMA is a nonprofit organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Corrosion & Oxide. The organization has 756 authors who have published 1307 publications receiving 25693 citations.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, three orthorhombic alloys with various β-stabilising elements contents (Ti-23Al-25Nb-0.35Si, Ti-22Al-13Nb -5Ta-3Mo) were investigated, with respect to their oxidation resistance in air at 800 °C.
Abstract: Aerospace activities as well as the power generation and automotive industries would definitely benefit from the potential weight savings and increased operation temperatures made possible by the use of orthorhombic titanium aluminides. A high effort is nowadays given in the development of these materials, based on the composition Ti2AlNb. They are attractive in comparison to the conventional titanium aluminides because of their good balance of specific mechanical properties at both room- and high-temperatures combined with good thermomechanical processing capabilities and a very good ignition resistance. Three orthorhombic alloys with various β-stabilising elements contents (Ti-23Al-25Nb-0.35Si, Ti-22Al-25Nb-1Mo-0.2Si, Ti-23Al-13Nb-5Ta-3Mo) were investigated, with respect to their oxidation resistance in air at 800 °C. Oxidation kinetics are discussed with regard to the influence of the alloying elements. Complete scale spallation occurred after 10 × 100 h and a multilayered oxide scale of alternating TiO2-rich and AlNbO4-rich layers with segregation of the refractory elements had developed. In addition to this catastrophical scale formation, two types of subsurface morphologies were obtained, which appeared to be successive development states of the inward progress of the oxidation mechanism. The orthorhombic materials were very sensitive to interstitial diffusion leading to severe embrittlement. A third type of subsurface morphology was found together with a thin adherent alumina rich oxide scale on the Ta-containing specimen. The protective morphology was associated with an interfacial zone of (Ti, Nb)-nitride and (Al, Nb)-rich metal phase. These observations and the “Ta-effect” are discussed in consideration of the literature data.
Oxidation von orthorhombischen Ti2AlNb Legierungen bei 800 °C in Luft
Die mit dem moglichen Einsatz von orthorhombischen Titanaluminiden verknupften Potentiale der Gewichtseinsparung sowie der Erhohung der Betriebstemperatur waren sowohl fur die Industriezweige Automobil, Luft- und Raumfahrt als auch Energieerzeugung von groser Bedeutung. Es bestehen daher zur Zeit grose Aktivitaten in der Entwicklung dieser auf der Zusammenseztung Ti2AlNb basierenden Werkstoffe. Im Vergleich zu den γ-TiAl-Werkstoffen besitzen die orthorhombischen Legierungen sowohl bei Raum- als auch bei hohen Temperaturen attraktive mechanische Eigenschaften in Verbindung mit einer guten thermomechanischen Verarbeitbarkeit und guter Feuerbestandigkeit.
Es wurde das Oxidationsverhalten dreier orthorhombischer Legierungsvarianten mit unterschiedlichen β-Stabilisatoren (Ti-23Al-25Nb-0.35Si, Ti-22Al-25Nb-1Mo-0.2Si, Ti-23Al-13Nb-5Ta-3Mo) bei 800°C in Luft untersucht. Nach einer diskontinuierlichen Oxidation fur 10 × 100 h hat sich ein schichtartiger Oxidaufbau bestehend aus abwechselnden TiO2- und AlNbO4-reichen Lagen ergeben. In den AlNbO4-reichen Schichten konnte eine Segregation der Refraktarelemente beobachtet werden. Unterhalb dieser Oxidschicht wurden abhangig vom Stadium des Oxidationsangriffes zwei Morphologien der Metallrandzone beobachtet. Die Legierungen zeigten eine starke Versprodung der Metallrandzone durch Eindiffusion von Sauerstoff. Lokal bildete sich auf der Ta-haltigen Legierung eine dunne Al-reiche Oxidschicht aus. Die Metallrandzone unterhalb dieser schutzenden Oxidschicht bestand aus (Ti, Nb)-haltigen Nitriden und einer (Nb, Al)-reichen Metallphase. Die experimentellen Ergebnisse werden in Zusammenhang mit den in der Literatur vorliegenden Daten verglichen und diskutiert.
28 citations
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TL;DR: In this article, the co-carbonization of coal-tar pitch with weak-coking coal mixtures for the production of high-strength metallurgical cokes for the blast furnace process was investigated.
28 citations
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TL;DR: In this article, a Dields-Alder addition of the two monomers first takes place, and the adduct reacts with a further monomer molecule, forming trimers and initiator radicals.
Abstract: In the thermal copolymerisation of styrene with acrylonitrile, a Dields-Alder addition of the two monomers first takes place. The adduct reacts with a further monomer molecule, forming trimers and initiator radicals. This results from the structure of the trimers and the kinetics of their formation. The initiating step is, therefore, analogous to the polymerisation of pure styrene.
Bei der thermischen Copolymerisation von Styrol mit Acrylnitril findet einleitend eine Diels-Alder-Addition der beiden Monomeren statt. Das Addukt reagiert mit einem weiteren Monomermolekul unter Bildung von Trimeren und Starterradikalen. Dies ergibt sich aus der Struktur der Trimeren und der Kinetik ihrer Bildung. Der Startschritt verlauft demnach analog der Polymerisation des reinen Styrols.
28 citations
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TL;DR: In this paper, a new palladium-coated PdCu foil at 423 K was used for direct hydroxylation of benzene to phenol and the highest selectivity was 9.6% with carbon dioxide being the dominant product.
28 citations
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20 Sep 2006TL;DR: In this article, a process for preventing or reducing biofilms on surfaces involves making the surface polarizable with a conductive coating, which can be applied on surfaces to prevent or reduce biofilm on surfaces.
Abstract: Process for preventing or reducing biofilms on surfaces involves making the surface polarizable with a conductive coating.
28 citations
Authors
Showing all 760 results
Name | H-index | Papers | Citations |
---|---|---|---|
Wolf B. Frommer | 105 | 345 | 30918 |
Michael W. Anderson | 101 | 808 | 63603 |
João Rocha | 93 | 1521 | 49472 |
Martin Muhler | 77 | 606 | 25850 |
Michael Hunger | 60 | 295 | 11370 |
Ivars Neretnieks | 44 | 224 | 7159 |
Michael Schütze | 40 | 343 | 6311 |
Jens Schrader | 38 | 129 | 4239 |
Roland Dittmeyer | 31 | 206 | 3762 |
Lei Li | 29 | 198 | 4003 |
Dirk Holtmann | 29 | 107 | 3033 |
Lasse Greiner | 26 | 74 | 1994 |
Klaus-Michael Mangold | 23 | 57 | 1590 |
A. Rahmel | 23 | 59 | 1967 |
Gerhard Kreysa | 22 | 78 | 1305 |