Effect of heat and mass transfer on the thermal decomposition of SrCO3 compacts

The thermal decomposition of spheres made of pressed SrCO3 powder was studied by the thermogravimetric analysis (TGA) technique. The temperature was measured simultaneously either at the surface of the sample or at the center of the sample by suitably placed thermocouples. The experimental results are compared to calculations wherein both heat- and mass-transfer aspects are considered. A steady state is assumed in the solution of heat and mass transfer through the product layer formed during the decomposition of SrCO3. It was found that the decomposition rate was controlled by chemical CO2 production in the beginning of the decomposition. External CO2 transfer also had a strong influence at the beginning, and CO2 diffusion through the porous SrO product layer affected the rate at later stages. The decomposition rate was also influenced, to some extent, by external heat transfer.