RT Journal Article
T1 Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres
A1 Velasco López, Francisco Javier
A1 Guzmán Fernández, Susana
A1 Moral Gil, Cristina
A1 Bautista Santa-Cruz, Alfredo
AB Oxidized aluminium microparticles have recently been proposed for manufacturing new, environmentally-friendly, protective coatings on stainless-steels and Ni-base alloys. The oxidation mechanisms of spherical aluminium microparticles of an average particle size of 3.5 mu m were studied. Accordingly, simultaneous differential thermal analysis-thermogravimetry tests were carried out in air at different temperatures, always above aluminium melting temperature. Scanning electron microscopy and XRD were also used for the interpretation of results. Weight gain and energy results were explained in terms of the different structural changes taking place in aluminium particles. Dehydroxylation process was identified. The transformation of amorphous alumina to gamma-Al2O3 was numerically evaluated and the alumina phase transformation (gamma-Al2O3 -> I +/--Al2O3) was also studied. The temperature ranges revealed the appearance of metastable phases (theta-Al2O3). Complete oxidation of particles can be obtained at 1,300 A degrees C in < 1 h, although this also takes place at lower temperatures if enough oxidation time is used. Activation energy of oxidation process at high temperature was also estimated, taking a value of 334 kJ/mol. High temperature oxidation causes the formation of hollow alumina spheres, without any aluminium left inside them.
PB Springer
SN 0030-770X
YR 2013
FD 2013-10
LK https://hdl.handle.net/10016/21637
UL https://hdl.handle.net/10016/21637
LA eng
NO This study was supported under the Project PARTICOAT (FP7-NMP-LARGE- 11329) funded by the European Union.
DS e-Archivo
RD 24 may. 2024