Effect of Retained Compression Strength on the Collapsibility of $CO_2$ Process

($CO_2$ 주형(鑄型)의 붕괴성(崩壞性)에 대한 잔류강도(殘留强度)의 변화(變化)에 관(關)한 연구(硏究)

Effects of retained compression strength on the collapsibility of $CO_2$ mold sand using sodium silicate were studied. The results obtained from the experiment are summurized as follows; 1) The sand mixtures increased their compression strength and retained compression strength when content of sodium silicate is high or mole ratio of sodium silicate is high. 2) Increase of retained strength has a maximum value at temperatures about $200^{\circ}C$. When the sample reached $800^{\circ}C$, the binder bridge are homogeneous. The retained strength is increased. 3) Decrease of retained strength at temperatures over $200^{\circ}C$ is caused by pore formation and additives of seacoal markedly accelerated pore formations.