Oxidation of aluminum foil under simulated high temperature annealing using thermogravimetry

Abstract

The oxidation rate of commercial aluminum foil (0.002 inches in thickness) was followed in air using a thermogravimetric analyzer as a simulated micro annealing oven. Rate constants were calculated for a parabolic rate law fit from 0.5 to 1.5 hours at temperatures from 510 to 630 ~ The maximum weight gain of 27 btg/cm was found at 621 ~ in air. An unusual adsorption at 93 ~ was observed in several atmospheres while bringing the sample up to isothermal temperature and was related to surface contamination collected during rolling. The results were compared to those for pure aluminum and found to be similar.The oxidation rate of pure aluminum surfaces at elevated temperatures in the presence of dry and moist oxygen has been studied extensively and the rate of reaction between water vapor and aluminum was found to be greater than that between the metal and oxygen; blister formation was also found to occur in the presence of water vapor [1].The study of the kinetics of oxidation has shown that the rate of oxidation does not follow either a parabolic rate law or a direct logarithmic law [2,3]. This was explained by the fact that the formation of 3:-alumina crystallites, which nucleate beneath the initial amorphous oxide film, are assumed to achieve a terminal thickness rapidly followed by radial growth. This growth proceeds at a constant velocity until the crystallites impinge on one another.A few experiments have been carried out on commercial 5052 aluminummagnesium alloys and the rate was found to be much faster than for high-purity aluminum and proceeded to much higher weight gains [4]. Electron diffraction examinations of oxidized specimens showed formation of magnesium oxide on the alloy. Oxidation rate was also shown to be a function of surface roughness. l he highly polished and smoother surfaces were oxidized at a much lower rate.Little has been reported on the air oxidation of "as roiled" aluminum foil or under conditions present in commercial rolling processes.The present study employed the use of a thermogravimetric analyzer (TGA) as a micro annealing oven to study oxidation rates of commercial "as rolled" aluminum foil under various conditions simulating the high temperature annealing process, referred to as homogenization.15"

Oxidation and waste-to-energy output of aluminium waste packaging during incineration: A laboratory study

“…The presence of Si and Fe oxides is due to the combustion-induced change in the composition of the starting alloy (which contains small amounts of Si, Fe, and other elements). The oxidation of the metallic aluminium in the packagings is incomplete, which agrees with the thermodynamic and physico-chemical characteristics of the Al-O system (Piehl, 1974). thickness % 6 lm), and 6.6 MJ/kg for the Group 3 packagings (mean aluminium lamina thickness % 60 lm).…”

Thermal analysis

“…The latter, together with impurity effects most probably contribute to the 34 to 54 kcal/mol spread in activation energy reported in the literature. Parabolic and linear law variations also were found with oxidation of Ti bars (153) and A1 foil (332). Activation energies for the decomposition of the hydrofluorides of the alkali metals and alkaline earths have been given (312), together with some of the issues associated with studies of these materials.…”