水玻璃有机酯自硬砂的试验研究

STUDY OF ESTER—CURED SODIUM SILICATE BONDED SAND FOR STEEL CASTINGS

本文介绍水玻璃有机酯自硬砂综合性能、合理配比,硬化速度控制以及高温残强,退让性和附加物溃散作用等的试验研究。研究表明:有机酯自硬砂具有良好的工艺性能,水玻璃用量可降到3.5-4%;溃散性明显改善,铸件落砂清理方便,质量良好;搭配使用不同的酯和水玻璃可方便地控制其硬化速度和可使用时间,以适应不同的环境气候和生产条件:此外,还运用扫描电镜研究了水玻璃有机酯砂的粘结桥形貌,对其固化和溃散机理以及附加物的溃散作用进行了探讨。

The technical properties,optimum mixture ratio,curing characteristics of organic ester-cured sodium silicate bonded sand were examined. The deformability,retained strength at high temperature and the effect of break-down agents were also tested.Experiments show that the estercured sand has advantages of higher cured strength,better collapsibility and casting quality.The addition of binder in mixture can be reduced to 3～4 %,By using different types of ester and changing the modulus of sodium silicate,the curing rate and life of the mixture can be easily controlled for various climate and productive conditions.Besides, the morphology of heated binder bridges of ester-cured sand was studied with scanning electronic microscope.The mechanism of the strength and collapsibility improvement has been discussed and some appreciable breakdown agents were also developed.