| There are many kinds of no bake self-hardening method using sodium silicate. When sodium silicate solution is mixed with calcium-orthosilicate powder hardening reaction is occured, which is based for self-hardening method at room temperature. The compression strength, surface stability and residual strength of mold are so related to the molecular ratio of sodium silicate and the content of calcium-orthosilicate powder that these properties are tested and studied, especially using domestic silicate sand, varing the content of 2CaO-SiO₂ from 1% to 4% at 7% of sodium silicate mixed. The results obtained in this study are as follows, 1) The compression strengths are getting still higher, along to the contents of 2CaO-SiO₂ up to 4% untill about 12 hours and after that time the strengths are inverted. 2) The final compression strength is much higher in case of low contents of 2CaO-SiO₂ and low molecular ratio. 3) The surface stability is not so varied along to the change of 2CaO-SiO₂ content and the molecular ratio. 4) The optimum properties can be obtained form ZIN HAE silica sand mixture at 7% of sodium silicate, molecular ratio 2.3 and 2% to 3% of 2CaO-SiO₂ powder. |
|
