MICROSTRUCTURAL AND SURFACE CHARACTERISTICS OF LEAD FREE BISMUTH BRONZE PRODUCED THROUGH THE FROZEN MOLD CASTING PROCESS

摘要

The frozen mold is a kind of sand mold which is produced by freezing the mixture of sand and water. The frozen mold casting process has the possibility to reduce the environmental load and the rapid cooling effect on cast products is expected. The effect of cooling rate on the microstructure of bronze castings was investigated. The frozen mold indicated better cooling property compared with conventional green sand mold. The microstructure of bronze castings produced through the frozen mold casting process was refined in the thinner sample but the quenching effect did not work well in the thicker sample. The surface condition of bronze cast was also examined. The surface of bronze castings produced using frozen mold consisting of only sand and water was rather rough. The surface roughness, however, was improved by adding colloidal silica solution into the sand mixture.