• Stanislav Kúdela, Jr.
• Opálek, Andrej
• Klimová, Alena
• Iždinský, Karol
• Beronská, Naďa
• Nagy, Štefan
• Štefánik, Pavol

Abstract

<jats:p>The Ni-NiO skeleton seems to be a good candidate for various applications in industry such as corrosion-proof filters or components in refrigerating systems and as preforms for reactive infiltration with molten metals.The present work was focused on preparation of Ni-NiO composite with higher, controlled porosity. Sintering of pure Ni powder always leads to a substantial closed porosity in almost whole sample volume [1,2]. To eliminate this, we added Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> particles with diameter of-32 +20 μm into the Ni powder (-75 +45 μm diameters) and sintered this loose powder mixture (Ni + 25 vol. % Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) in air by progressive heating up to 800 °C followed by 2 hours isothermal exposure. As a control, pure Ni powder was sintered under the same conditions. Thermal oxidation of loose powder samples performed in alumina crucible indicates that the strongest oxidation occurred in the top part of sample, while the bottom part was the least oxidized. Therefore, it was necessary to run the thermal oxidation once more, but out of the crucible, to ensure the sufficient diffusion of oxygen to the whole volume of sample.</jats:p>

Topics

• porous
• corrosion
• Oxygen
• reactive
• composite
• porosity
• sintering