Due to aging of sodium silicate sand after mixing

it can reduce its strength

collapsibility

moisture resistance and so on.Sodium silicate was modified in an ultrasonic processor with a frequency of 40 kHz and a power of 480 Wto test its performance.The results show that the viscosity of sodium silicate is decreased with the increase of ultrasonic treatment time.At 30 min

the viscosity of sodium silicate is decreased by 11%

and the wettability of sodium silicate is increased by 13%～37% compared with that of ones before modification.The dry strength of sodium silicate sand is increased by 48%.At the same time

the residual strength of sodium silicate sand at high temperature is decreased by 41%

and the hygroscopicity of sodium silicate sand prepared by mixing sodium silicate sand before and after ultrasonic modification is increased by 8%.The results show that ultrasonic treatment can improve the strength and hygroscopicity of sodium silicate sand

and improve the collapsibility of moulding sand as well as reducing the amount of sodium silicate.