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"

A NOVE L vapour-phase conversion of aliphatic aldehydes and ketones into olefins over a supported manganese dioxide catalyst has been observed. In previous reports of similar reactions, either the conversions have been performed in a hydrogen atmosphere or longer-chain olefins were formed through condensation.1 This is the first report of the direct catalytic conversion of aldehydes and ketones into the corresponding olefins in a non-reducing atmosphere.The :-eactions were carried out with a pulsed microcatalytil: reactor similar to the one described by Pines.2 The reaAion temperature was 550" at a pressure of 50-75 lb./in.2 of nitrogen with contact times less than 1 sec. 1 p1. Samples of low-molecular-weight aliphatic aldehydes and ketones were pulsed over Harshaw (Mn-0201T) manganese dioxide (1 g.) supported on 1/8 in. alumina pellets. The effluent was analysed directly by g.1.c. and retention times and i.r. analysis of samples obtained from multiple injections were used to identify the products.The following conversions were obtained without optimizing the conditions:Crotonaldehyde -+ Butadiene 25% n-Heptaldehyde -+ Hept-Z-ene -5%Pentan-2-one -+ Pent-l-ene 6ZY0Cyclohexanone -+ Cyclohexene 22%The method appears to be of general application based on a limited number of reactions, but reactions on the macro-scale have not been examined as yet.