Internal Oxidation of a Fe-Cr Binary Alloy at 700-900 degrees C: The Role of Hydrogen and Water Vapor

Internal oxidation of Fe-2.25Cr has been studied in Fe/FeO Rhines pack (RP) and H-2/H2O gas mixtures at 700-900 degrees C. A novel exposure technique allowing RP experiments in dual atmosphere conditions was developed. No measurable effect of hydrogen on lattice oxygen permeability in ferrite could be detected: neither in single nor in dual atmosphere conditions. The H-2/H2O atmosphere was found to induce stronger oxidation attack at alloy grain boundaries resulting in a morphology similar to intergranular stress corrosion cracking often reported in nuclear technology. The intergranular oxidation attack was demonstrated to be independent of the dual atmosphere effect, i.e., hydrogen dissolved in the alloy

Effect of Hydrogen on the Internal Oxidation of a Pd–Cr Alloy in Dual-Atmosphere Conditions

The effect of hydrogen on oxygen permeability has been studied in a diluted Pd–Cr alloy in dual- and single- atmosphere conditions between 600 and 950\ua0\ub0C. The 0.3\ua0mm thick Pd–1.5Cr foil was exposed in dry and humid air as well as in dual-atmosphere conditions, with one sample surface being exposed to air and one to hydrogen, as encountered in solid oxide fuel cells. At all temperatures, Cr oxidized internally forming internal oxidation zones which were measured in metallographic cross sections. Below 800\ua0\ub0C, an external layer of PdO formed on the surface decreasing the internal oxidation kinetics. No measurable effect of hydrogen on the internal oxidation of Cr in Pd has been detected

Synchrotron Sub-μ X-ray Tomography of Kirkendall Porosity in a Diffusion Couple of Nickel-Base Superalloy and Nickel after Annealing at 1250 \ub0C

Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel-base superalloy CMSX-10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 \ub0C, where the strengthening γ′-phase is partially dissolved. The porosity is studied by X-ray sub-μ tomography with a spatial resolution of about 0.353 μm3 at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. It is found that depending on the distance from the interface the Kirkendall pores take different shapes: octahedral, rounded pyramidal, drop shaped, dendritic, pear shaped, and joint shapes. Such a variety of pore morphologies indicates a complex multistage process of porosity nucleation and growth under vacancy supersaturation of different degrees. The experimental findings are interpreted on the basis of the results of diffusion modeling. It is shown that the kinetics of porosity growth is essentially influenced by the dissolution of the γ′-phase

High temperature oxidation of AISI 441 in simulated solid oxide fuel cell anode side conditions

This study investigates the corrosion of AISI 441 in simulated anode conditions of solid oxide fuel cells (SOFCs). Several parameters such as temperature, humidity, surface condition, pre-oxidation temperature and environment, were investigated. Samples pre-oxidized at 800 \ubaC were protective at 550–900 \ubaC, while as-received samples showed protective behavior only at 900 \ubaC. Additional exposures performed at 600 \ubaC revealed the negative effect of increasing steam concentration, the beneficial effect of grinding, while pre-oxidation at 600 \ubaC did not improve the protectiveness. The role and the interplay of the aforementioned factors are discussed

The effect of hydrogen on the breakdown of the protective oxide scale in solid oxide fuel cell interconnects

In this study, the effect of hydrogen, on the degradation of AISI 441 interconnect, under solid oxide fuel cell operating conditions was investigated between 500−800 \ub0C for 336 h. As a new hypothesis, it is concluded that, hydrogen impedes Cr diffusion, probably in the grain boundaries, leading to the breakdown of the protective oxide scale. This effect is most severe at 600 \ub0C, while at lower or higher temperatures the effect is attenuated. Cr diffusion is enhanced at high temperatures, whereas protective scales can be obtained at low temperatures with a lower amount of Cr

High-temperature oxidation behavior of additively manufactured IN625: Effect of microstructure and grain size

High-temperature oxidation of additively manufactured (AM) Ni-base alloy IN625 has been studied in air and Ar-5%H2-3%H2O at 900–1000 \ub0C. AM material is found to oxidize faster than the conventionally manufactured (CM) IN625 due to severe intergranular oxidation observed in the former. The AM IN625 was heat treated at 1100–1250 \ub0C and hot rolled at 980 \ub0C in order to modify the AM microstructure, primarily grain size, and analyze its role in alloy oxidation behavior. Grain size is shown to affect overall oxidation kinetics but not the intergranular oxidation morphology

Reform of decentralization and regional policy in the Visegrad

In our work, we highlight how, in particular, territorial changes of public authority have been taking place and analyze the current state of the territorial basis of municipal power (local governance) in the countries under review via comparative qualitative research methods. As a result, it appears that Slovakia, like other Visegrad countries, boasts a high level of territorial fragmentation. In conclusion, the corresponding changes have made it possible for the former post-socialist countries to experience the benefits from structural and regional EU policies through cooperation and interaction.У нашій роботі ми висвітлюємо, як, зокрема, відбулися територіальні зміни публічної влади та аналізуємо сучасний стан територіальної основи муніципальної влади у країнах, що переглядаються, шляхом порівняльних якісних методів дослідження. Як результат, виявляється, що Словаччина, як і інші країни Вишеграду, має високий рівень територіальної роздробленості. На закінчення, відповідні зміни дали змогу колишнім постсоціалістичним країнам відчути переваги від структурної та регіональної політики ЄС завдяки співпраці та взаємодії

Institutional transformation of the financial basis of the local self-government

The study investigates the institutional transformation of financial basis of the local self-government in the Czech Republic, Hungary and Poland via comparative qualitative research methods. As a result, the Czech Republic also failed to avoid a downturn, but since 2010, the economy has started to grow and, consequently, there has been an increase in GDP at 1%. In conclusion, local and regional development must be supported by planned finances, rather than by the financing of individual projects, specifically, financial instruments, the structure and flexibility of which is consistent with the objectives of the integrated program of development of local self-government.У дослідженні висвітлено інституційну трансформацію фінансової бази місцевого самоврядування в Чехії, Угорщині та Польщі за допомогою порівняльних якісних методів дослідження. Як результат, Чеська Республіка не змогла уникнути спаду, але з 2010 року економіка почала зростати і, отже, спостерігається зростання ВВП на 1%. На закінчення, місцевий та регіональний розвиток повинен підтримуватися плановими фінансами, а не фінансуванням окремих проектів, зокрема, фінансових інструментів, структура та гнучкість яких відповідає цілям інтегрованої програми розвитку місцевого самоврядування

Institutional transformation of the financial basis of the local self-government

The study investigates the institutional transformation of financial basis of the local self-government in the Czech Republic, Hungary and Poland via comparative qualitative research methods. As a result, the Czech Republic also failed to avoid a downturn, but since 2010, the economy has started to grow and, consequently, there has been an increase in GDP at 1%. In conclusion, local and regional development must be supported by planned finances, rather than by the financing of individual projects, specifically, financial instruments, the structure and flexibility of which is consistent with the objectives of the integrated program of development of local self-government.У дослідженні висвітлено інституційну трансформацію фінансової бази місцевого самоврядування в Чехії, Угорщині та Польщі за допомогою порівняльних якісних методів дослідження. Як результат, Чеська Республіка не змогла уникнути спаду, але з 2010 року економіка почала зростати і, отже, спостерігається зростання ВВП на 1%. На закінчення, місцевий та регіональний розвиток повинен підтримуватися плановими фінансами, а не фінансуванням окремих проектів, зокрема, фінансових інструментів, структура та гнучкість яких відповідає цілям інтегрованої програми розвитку місцевого самоврядування