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Co-based alloys are known to be high oxidation-resistant material and used in several high temperature applications. During high temperature oxidation, duplex oxides containing Co and Cr were formed. It was thermodynamically elucidated that when the growing scale was thick enough, the partial pressure of O2 in the scale dropped. Then, the reduction of CoO occurred for promoting O2 which was responsible for Cr2O3 production. This work experimentally proved this point by in situ characterising Co-27Cr-6Mo at high temperatures in air by X-ray diffractometer in a grazing incident mode and metallic Co was confirmed to be formed by the reduction of CoO consistent with the image taken and analysed by field emission scanning electron microscope, energy-dispersive X-ray, and electron backscatter diffraction. Furthermore, the change in lattice parameter and the phase transition were observed when the temperature was altered.

Biogas is an alternative source of fuel potentially used to run solid oxide fuel cells (SOFCs). It mainly consists of CH4 and CO2 which can degrade the SOFC interconnect, which is typically made of stainless steel. To investigate the effect of each gas constituent, we focussed here on the effect of CO2 on high-temperature oxidation behavior of and scale adhesion on the stainless steel interconnect, Type 430 stainless steel. The samples studied were oxidised in CO2 at contents of 5–100% at 800 °C. The oxidation kinetics were found to be parabolic with the rate constant increasing when the CO2 content increased. The scale adhesion was assessed using a tensile-test method. The scale formed in the atmosphere containing higher CO2 content exhibited poorer scale adhesion, as indicated by a lower strain initiating the first spallation and a larger spallation percentage after the first spallation took place. The worsened scale adhesion relates to pores formed at the scale/steel interface. The adhesion energies were further quantified giving the values of about 40–100 J m–2. Oxidation mechanisms were suggested based on the dependence of the parabolic rate constant on the oxygen partial pressure and the inward diffusion of carbon-bearing species. [ABSTRACT FROM AUTHOR]

The adsorbent pellet for As(III) removal was prepared from ground oyster shell and rice husk ash. The effects of particle size of oyster shell powder (OS) and the ratio between the OS and Treated rice husk ash (TRHA) on the stability of the adsorbent pellet were studied. The adsorbent pellet was characterized by XRD, XRF and SEM. The solubility and As(III) adsorption tests were performed. The results showed that the adsorbent pellet prepared from OS size