DECHEMA

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.

Inhibition of Hot Corrosion by MgSO4 and BaSO4 and its potential dependence

Abstract: Electrochemical corrosion measurements have been performed with IN 100 in a (mole %) 90 Na2SO410 K2SO4 melt with different additions of MgSO4 and BaSO4 at 1173 K in order to investigate the inhibition effect of these compounds and its potential dependence. Potentiostatically controlled measurements as well as free corrosion potential measurements with the determination of the polarization resistance have been performed. The inhibition effect of MgSO4 is strongly potential dependent. At negative potentials, where oxygen ions are produced by electrochemical side reactions, MgO is precipitated at the surface of the metal and becomes incorporated into the scale. This kind of MgO-rich scale is resistant to basic fluxing because MgO is not dissolved in basic media. At positive potentials, where acid SO3 is produced by discharge of SO4-ions, MgSO4 yields no or only very little inhibition. BaSO4 additions alone do not yield inhibition effects. However, additions of BaSO4 to melts containing MgSO4 improve the inhibition effect of the latter. The mechanism of this synergistic effect is not completely understood. Inhibition der sulfat-induzierten Heisgaskorrosion durch MgSO4 und BaSO4 und ihre Potentialabhangigkeit Elektrochemische Korrosionsuntersuchungen wurden mit IN 100 in einer Schmelze aus (Mol-%) 90 Na2SO410 K2SO4 mit verschiedenen Zusatzen an MgSO4 und BaSO4 bei 1173 K durchgefuhrt, um die Inhibition dieser Verbindungen und ihre Potentialabhangigkeit zu untersuchen. Es wurden sowohl potentiostatisch kontrollierte als auch Versuche beim Freien Korrosionspotential mit Messung des Polarisationswiderstandes durchgefuhrt. Die Inhibition von MgSO4 ist stark potentialabhangig. Bei negativen Potentialen, bei denen in elektrochemischen Nebenreaktionen Sauerstoffionen gebildet werden, wird MgO auf der Werkstoffoberflache abgeschieden und teilweise in die Zunderschicht eingebaut. Diese MgO-reiche Zunderschicht ist bestandig gegen basischen Aufschlus, weil MgO in basischen Schmelzen unloslich ist. Bei positiven Potentialen, bei denen durch Entladen von SO4-Ionen die Saure SO3 entsteht, wird keine oder nur sehr geringe Inhibition gefunden. Zusatze von BaSO4 allein ergeben keinen Inhibitionseffekt. Zusatze von BaSO4 zu einer MgSO4-haltigen Schmelze verbessern jedoch erheblich die Inhibitionswirkung von MgSO4. Der Mechanismus dieses synergistischen Effektes wird nicht vollstandig verstanden.

Investigations into the application of a process for the determination of microbial activity in biofilms

Abstract: The formation of biofilms in a waste paper medium was studied in a pilot plant by analysing the redox potential in the biofilm. Miniaturised redox electrodes were applied at the reactor wall/biofilm phase boundary. With this measurement set-up, it was possible to demonstrate the effectiveness of biocides and thus to avoid under- and over-doses with these agents. The redox signals measured were correlated with reference methods, such as colony-forming units and dehydrogenase activity.

White Mutants of Chloroperoxidase-Secreting Caldariomyces fumago as Superior Production Strains, Revealing an Interaction between Pigmentation and Enzyme Secretion

Abstract: By mutant-colony screening of Caldariomyces fumago, several white mutants were isolated that are superior strains for the production of the valuable enzyme chloroperoxidase (CPO). Their culture supernatant lacks the contaminating dark pigment, which simplifies downstream processing. Furthermore, the CPO content increased significantly faster than the wild-type rate, which uncovers possible interactions between pigmentation and enzyme secretion.

Chlorine Attack of Carbon Steel Between 350 and 500 °C and Its Importance Regarding Corrosion in Waste Incineration

Abstract: Corrosion in waste to energy (WTE) plants is an extremely interesting issue, involving complex atmosphere and deposit interactions. In this work, the influence of the complex WTE atmosphere and its various constituents was simulated between 350 and 500 °C in order to obtain a better understanding of the corrosion mechanisms occurring in such atmospheres. For this purpose, the typical flue gas mixture of WTE plants was reduced to simpler systems, and the impact of gaseous species typically contained in WTE plants atmospheres on the corrosion rate of the carbon steel 16Mo3 was investigated. Four different atmospheres were used in this work: “full” WTE atmosphere 0.1%HCl + 0.01%SO2 + 8%O2 + 17H2O + 10%CO2 + N2, 0.1%HCl + 15 ppmO2 + 0.01%SO2 + N2, 0.1%HCl + 15 ppmO2 + N2, and 0.1%HCl + 450 ppmO2 + N2. All exposures were carried out in the temperature range between 350 and 500 °C (30 °C steps) for up to 900 h. Parabolic, paralinear, and linear mass change dependent on time, temperature, and atmosphere was observed, the metal consumption as a function of temperature was determined, and the corrosion scales were analyzed and compared with results of field tests. Finally it is shown that the test results obtained from low-oxygen atmospheres match best the corrosive scales observed in field-tested samples.

Numerische Untersuchungen zur optimalen Wärmeleitfähigkeit in Mikrowärmeübertragerstrukturen

Abstract: Proposition d'une modelisation du transfert de chaleur dans les micro-echangeurs de chaleur