Thermal degradation mechanism and kinetics of aluminum-copper green bodies prepared by gelcasting

Aluminum-copper green bodies were successfully prepared by a non-aqueous gelcasting system. Scanning electron microscopy observations showed that the powder particles were completely wrapped by the polymer before degreasing,and the polymer in the metal body was completely removed after degreasing. A three-dimensional network polymer structure was obtained by the reaction mechanism. The degreasing process of the metal body was investigated by means of differential scanning calorimetry,thermogravimetry-derivative thermogravimetry and thermogravimetry-Fourier transform infrared spectroscopy. The kinetic equations and parameters were gotten according to Coats-Redfern method for non-isothermal weight loss curves. The results indicate that at different heating rates the reaction order is 1,the activation energy and pre-exponential factor are ranging from 79.86 to 108.63 kJ·mol^-1 and 10⁶ to 10⁷ min^-1,respectively. The activation energy reaction is sensitive to temperature and dynamics. The degreasing process is divided into two stages:a slight weight loss over a wide temperature range of 240-350℃ is due to the random chain scission and the main weight loss around 380 to 425℃ is attributed to depolymerization of monomers from the main chains and decrosslinking of the network polymer. The emissions of CO₂,CO,NO₂ and H₂O are identifled during the degreasing process.