TY - JOUR A1 - Lee, Jun-Seob A1 - Radnik, Jörg A1 - Bäßler, Ralph T1 - Passivity of alloy 31 in green-death solution JF - Materials and Corrosion N2 - The passivation behavior of alloy 31 was investigated as a function of passivation potential in a green-death solution at 40 °C. The alloy 31 surface is in a stable passive state during cyclic potentiodynamic polarization. In potentiostatic polarization of alloy 31, passive current density increases with an increase in the passivation potential. Electrochemical impedance spectroscopy (EIS) and Mott–Schottky (M–S) analysis showed that a more defective n-type semiconductive passive film forms as the potential increases. X-ray photoelectron spectroscopy (XPS) revealed that passive film consists of mainly chromium and minor iron and nickel oxides. The increase of the applied potential is considered to be a reason for the change in passive film stability. KW - Passive film KW - Steel KW - Alloy 31 KW - X-ray photoelectron spectroscopy PY - 2018 DO - https://doi.org/10.1002/maco.201709996 SN - 0947-5117 SN - 1521-4176 VL - 69 IS - 9 SP - 1218 EP - 1226 PB - Wiley-VCH CY - Weinheim AN - OPUS4-45938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dang, Thi Thuy Hanh A1 - Seeburg, Dominik A1 - Radnik, Jörg A1 - Kreyenschulte, Carsten A1 - Atia, Hanan A1 - Vu, Thi Thu Ha A1 - Wohlrab, Sebastian T1 - Influence of V-sources on the catalytic performance of VMCM-41 in the selective oxidation of methane to formaldehyde JF - Catalysis Communications N2 - VMCM-41 catalysts from two different tetravalent Vanadium sources, hydrothermally synthesized after a mild gelation step at room temperature, were used as catalysts for the selective oxidation of methane to formaldehyde. Vanadyl acetylacetonate as VMCM-41 precursor, facilitates highest VOx density with predominance of monomeric and a small portion of low-oligomeric VOx species. It produces CH2O in high yield and the highest space time yield (STYCH2O) reaches 5.3 kgCH2O·kgcat −1·h−1 at 600 °C (rate of formation, rCH2O of 363 h−1). VMCM-41 synthesized from vanadyl sulfate hydrate precursor contains a more significant portion of low-oligomeric species. With a lower V loading, these VOx species are significantly less active resulting in a Maximum STYCH2O of 2.7 kgCH2O·kgcat −1·h−1 at 625 °C (rCH2O of 243 h−1). KW - VOx catalyst KW - Methane KW - Formaldehyde PY - 2018 DO - https://doi.org/10.1016/j.catcom.2017.09.004 SN - 1566-7367 VL - 103 SP - 56 EP - 59 PB - Elsevier Science AN - OPUS4-42820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lee, Jun-Seob A1 - Radnik, Jörg A1 - Bäßler, Ralph T1 - Electrochemical behavior of UNS N08031 in Green-Death-solution T2 - Conference Proceedings NACE International Corrosion Conference 2018 N2 - The electrochemical behavior of UNS(1) N08031 was investigated as a function of electrode potential in Green-Death(2) solution at 40 °C. The UNS N08031 surface is in a stable passive state during cyclic potentiodynamic polarization without an initiation and/or propagation of localized corrosion. In potentiostatic polarization of UNS N08031 for 3600 s, passive current density increases with an increase in the passivation potential from 0.7 to 1.0 VSSE (silver/silver chloride reference electrode in saturated potassium chloride) Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis showed that a more defective n-type semiconductive passive film forms as the potential increases. X-ray photoelectron spectroscopy (XPS) revealed that passive film consists of mainly chromium and minor iron and nickel oxides. The mechanism of the defective passive film formation is discussed. The increase of the applied potential is considered to be a reason for the change in passive film stability. T2 - NACE International Annual Corrosion Conference CY - Phoenix, AZ, USA DA - 15.04.2018 KW - Steel KW - Passive film KW - X-ray photoelectron spectroscopy PY - 2018 SP - 10631, 1 EP - 9 PB - Omnipress CY - Houston AN - OPUS4-44915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -