A' in Shams University, Abbassia - Cairo,
Pages: 16 Published: Jan 1966
The thermal decomposition of a parent material presents a common tool in the preparation of active solids, mainly oxides. In lime-burning practice several factors are now known to affect the activity of the produced oxide. Among these factors are the structure of the initial material, temperature and duration of calcination, and the presence or absence of air during decomposition.
The present investigation deals with a new factor which may appreciably affect the activity of the produced oxide, namely, the effect of copper x-irradiation.
Copper x-irradiation of the parent material did not cause any variation of the surface area of the starting material or its decomposition products. But the irradiation of the partially or the completely dehydrated products resulted in measurable changes of the surface area. These changes were traced for products heated under vacuum at different temperatures for fixed durations, and for products heated at constant temperatures for various durations.
For products heated for a fixed duration of heating at different temperatures, all specimens showed a tendency for loss of area upon irradiation. Both the irradiated and unirradiated specimens give an area-temperature of decomposition curve characterized by a maximum, but this maximum was more sharp and was shifted to lower temperatures in the case of the irradiated specimens. Irradiation seems to assist well in reducing high area solids and activating the process of sintering.
The effect of variation of duration of heating at a fixed temperature on the surface area showed measurably higher areas for the irradiated than unirradiated specimens for incompletely decomposed samples. As decomposition approached completion the effect was reversed and the irradiated products showed smaller areas than the corresponding unirradiated samples.
The results are discussed mainly to show the effect of irradiation on the different stages followed by a solid during thermal decomposition; these stages are dissociation, recrystallization, packing, and finally sintering, and a possible interpretation is presented.
Paper ID: STP44638S