Influence of water-glass grade and quantity on residual strength of microwave-hardened moulding sands. Part 1

The paper presents a research on influence of dielectric drying process on mechanical properties of water-glass containing moulding sands. Examined were moulding sands containing additions of 1.5 and 2.5 % of hydrated sodium silicate grades 145, 149 and 150, most often used in foundry practice. Standard, cylindrical specimens for mechanical testing were held at temperatures from 100 to 1200 oC for 30 minutes and next cooled-down to ambient temperature. Then their residual strength was determined. Comparison of the obtained results with literature data indicates that dielectric drying is favourable for reduction of residual strength of used water-glass moulding sands, and thus improves their knock-out properties.