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신운용,권해욱,남원식 ( Un Yong Shin,Hae Wook Kwon,Won Sik Nam ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.6
N/A The effect of sodium gluconic acid on the collapsability of the sodium silicate type CO₂ mold was studied. The bending strength was saturated with gassing CO₂ for 60 sec. under l㎏/㎠ and with the flow rate of 10ℓ /min. It was decreased with aging after having been fully hardened. The retained strength was reduced in the heating temperature range of 100∼1,100℃ and the retained strength peak near the heating temperature of 100℃ was removed by the effect of the sodium gluconic acid. Silica gel, Na₂CO₃and dehydrated sodium silicates were formed from the binder of sodium silicate with the addition of sodium gluconic acid at the heating temperature of 100℃. Na₄SiO₄was formed by the reaction of Na₂O, from decomposed Na₂CO₃, with the dehydrated sodium silicate at 500℃. The crystobalite type of SiO₂was formed at 900℃. The sodium gluconic acid had no effect on the bending strength at around 1,100℃ due to the combustion loss of it.