The adsorption ability of powders obtained by pulsed electrical discharge in cryogenic liquids.

The adsorption ability, weight loss and desorption heat of micron-sized and nano-sized powders of shape memory B2 alloys Ti-Ni, Ni-Al, Ni-Mn-Ga, Cu-Al-Ni, glass-forming alloy Zr-Ni-Cu-Ti-Al and pure Ti and Ni are considered. Powders were obtained by electrical pulse discharge method (or spark erosion method) in liquid nitrogen or liquid argon. The porous structure of the surface and the body of the particles, the presence of hollow particles and the sponge structure of the nanofraction are the factors that contribute to the absorptive capacity of powders. Studies performed by the thermogravimetric analysis have shown that powders emit gases during the heating. Differential scanning calorimetry analysis reveals that the gases are released with significant heat effect. It is supposed that this is the result of desorption of gases adsorbed during the powders processing and storage as well as oxidation and reduction reactions of alloy components. In addition repetitive moisture absorption is possible when cooling powders below 0 °C followed by desorption during the consequent heating. [ABSTRACT FROM AUTHOR]