Evaluation of Microwave Heating of Protective Coatings Used in the Lost Foam Technology

Presented are results of a preliminary research on determining a possibility to use microwave radiation for drying casting protective coatings applied on patterns used in the lost foam technology. Taken were measurements of permittivity ε_r and loss factor tgδ at 2.45 GHz, as well as attempts were made of microwave drying of a protective coating based on aluminium silicates, applied on shapes of foamed polystyrene and rigid polymeric foam. Time and results of microwave drying were compared with the results obtained by drying at 50 °C by the traditional method commonly used for removing water from protective coatings. Analysis of the obtained drying kinetics curves demonstrated that selection of proper operation parameters of microwave equipment permits the drying time to be significantly shortened. Depending on kind of the pattern material, drying process of a protective coating runs in a different way, resulting in obtaining different quality of the dried coating.