Effect of Methyl Silicone Oil and Poly(vinyl Alcohol) On the Moisture Resistance of Ester-hardened Sodium Silicate Bonded Ceramic Sand

Sodium silicate binder as a binder for sand casting has the advantages of green, non-polluting, low cost, but the problem of strong hygroscopicity of sodium silicate bonded ceramic sand (SSBCS) has been pending solution. In this paper, the effect of methyl silicone oil and poly(vinyl alcohol) on the moisture resistance of ester-hardened SSBCS was studied, aiming to solve the problem of high moisture absorption of SSBCS. The results showed that the optimum ratio was 15% methyl silicone oil and 3% poly(vinyl alcohol). Compared with unmodified SSBCS, the moisture absorption rate of SSBCS modified by methylsilicone oil and poly(vinyl alcohol) at 2, 4, 6 and 8 h decreased by 0.2%, 0.18%, 0.32% and 0.51%, respectively, and the strength loss rate at 2, 4, 6 and 8 h decreased to 0. Characterization analysis concluded that methyl silicone oil and poly(vinyl alcohol) improved the strength of SSBCS by absorbing free sodium ions (Na+) from the sand and by covering the surface of SSBCS with a film to reduce water absorption.