水玻璃砂粘结桥形貌的扫描电镜研究

STUDY ON THE BINDER BRIDGE MORPHOLOGY OF SODIUM SILICATE BONDED SANDS BY SCANNING ELECTRON MICROSCOPY

本文介绍了普通水玻璃砂、ＣＯ２硬化改性砂和有机酯自硬砂的配比和残强──温度变化．在此基础上著助于扫描电镜观察了各种水玻璃砂在加热和冷却后砂粒间粘结桥的形貌．从而加深了解各种附加物（改性剂、溃散剂、硬化剂等）降低残强、提高溃散性的作用机理，促进水玻璃砂研究工作的开展．扫描电镜研究表明．为了改善水玻璃砂的溃散性．从粘结桥的形貌来说．重要的是：①减少砂粒间粘结桥的数量；②在加热后的粘结桥中做成大量的孔洞或微裂纹．破坏其连续性；③削弱粘结膜与砂粒间的附着强度；④形成难熔的化合物．改变粘结膜的组成和结构。在生产实践中应用经改性处理的水玻璃ＣＯ２硬化砂或有机酯自硬砂．均可以达到（或部分达到）上述目的．具有良好的溃散效果。

In this peper three types of sodium silicate hoded sands were examined:1 ) ordinary,2)modified with TPN,3) organic ester-cured. The compostions of the mixtures were introduced and the retained strength at different temperatures were tested. Based upon this, the morphology of heated binder bridges between the grains was studied by scanning electron microscopy. These studies help the deeper understanding the mechanism of additives (modifier, collapsing agent,curing agent etc.) in decreasing retained strength and in improving collapsibility, and Promote the research of sodium silicate bonded sands.The scanning electron microscopy invetigation shows that in order to improve the collapsibility of the mixtures it is important that:1 )to reduce the amount of binder bridges between the grains,2) to form many holes and fine cracks in the heated binder bridges and thus to destroy their continuity,3)to weaken the adhesive strength between the grains and the binder film,4)tochange the compostion and structure of binder bridges by composing hard-meltable compounds.APPlied the modified or organic ester-cured sodium silicate bonded sands in the Practical production,above objects have been attained and better collapsibility has been proved.