Wyniki 1-1 spośród 1 dla zapytania: authorDesc:"KAZIMIERZ PRZYBYLSKI"

Physicochemical properties of steel/coating composite interconnector for planar-type Solid Oxide Fuel Cell

Czytaj za darmo! »

A review is presented on the oxidation kinetics, electrical properties, chromium vaporization rate and microstructure investigations of the oxide products formed on Fe-25 wt.-%Cr steel uncoated and coated by the screen printing method with thick fi lms of (La,Sr)CoO3, (La,Ca)CrO3, (La,Sr)CrO3, MnCo2O4 and Mn1.5Cr1.5O4 in air and H2/H2O gas mixture at 1023-1173 K for up to 1000 hrs. To improve the poor electrical conductivity of the chromia scale, formed on uncoated steel during the oxidation process, the above electronic conducting thick fi lms composed of paste containing an organic binder and powders prepared via “wet chemical" methods were applied. The oxidation process of the coated steel, taking place in variable temperature cycles, shows good compactness of the conducting layer, as well as good adhesion to the metal substrate, as determined by the structural modifi cation of the intermediate, chromia-rich layer formed between the coating and metal substrate. The obtained kinetics data revealed that the oxidation reactions followed approximately the parabolic rate law over the applied temperature range. The calculated parabolic rate constants for the oxidation of DIN 50049 uncoated and coated at 1023-1173K were of the order of 10-13 to 10-14 g2/cm4, which are typical of chromia-formers. The values of the in situ area specifi c resistance (ASR) measurements by dc two-probe technique for the Fe-25Cr/(La,Sr)CoO3, Fe-25Cr/(La,Ca)CrO3, Fe-25Cr/(La,Sr) CrO3, Fe-25Cr/MnCo2O4 and Fe-25Cr/ Mn1.5Cr1.5O4 composite materials, exposed to air and H2/H2O gas mixture at 1073 K, are lower than the acceptable ASR level of the order of 0.1 Ω·cm2 for the SOFC metallic interconnect material. Vaporization measurements of the studied coating layers, performed in humidifi ed air under fl ow-rate independent conditions at 1073 K, revealed a decreasing volatilization rate of chromia species from the coating materials in comparison with the valu[...]

 Strona 1