An improved sodium silicate binder modified by ultra-fine powder materials

• Main Authors: WANG Ji-na, FAN Zi-tian, WANG Hua-fang
• Format: Article
• Language: English
• Published: Foundry Journal Agency 2007-02-01
• Series: China Foundry
• Subjects: sodium silicate binder modification; ultra-fine powder materials; bonding strength; moisture resistance; collapsibility
• Online Access: http://www.foundryworld.com/uploadfile/2008111840198909.pdf

This paper presents a new method of modifying sodium silicate binder with ultra-fine powders. The sodium silicate binder modified by ultra-fine powder A and the organic B can reduce the addition amount of the binder. The results indicate that the 24 h strength has increased by 39.9% at room temperature and the residual strength has decreased by 30.7% at 800℃, compared to the conventional sodium silicate. An available material to improve the moisture resistance was also found by adding about 2% more inorganic C, and it can increase the moist strength by 20%. In the end, the microanalyses are given to explain the modifying machanism, i. e., the ultra-fine powder A can refine the sodium silicate binder to avoid holes in the binder bond, which can increase the 24 h strength at room temperture, and can lead to more cracks in the bond after the molding sand is heated to 800℃. This is because of the stress caused by the new eutectic complex of modified sodium silicate binder.