DEVELOPMENT AND EVALUATION OF A NEW ECO-FRIENDLY SODIUM SILICATE-BASED BINDER SYSTEM

Although sand systems containing Na-silicate binder present several environmental and economic advantages, technological applications are restricted due to their poor knock-out properties and low moisture resistance. Thus, many investigations have been performed recently to eliminate these undesirable handicaps of Na-silicate binder. In this study, the technological importance of a recently developed Na-silicate binder with a liquid hardener and its applicability in a mold/core system have been investigated. Further, a casting trial of a tank rear idler wheel has been performed by using the molds prepared with the current Na-silicate binder, and the observations have been evaluated. It has been determined that using Na-silicate binder results in more important advantages and benefits such as shorter period (10s) for CO2 application, sound mold surface without cavity, good gas permeability, long shelf-life at high moisture environment (90% moisture at 23 degrees C for 24 h), and achieving silica sand-based mold/core systems with superior shakeout property than that of the conventional ones. It has been observed that the preparation of molds with the current Na-silicate binder hardened by CO2 process and the liquid Na-silicate hardener provides a practically odorless and fast process, and outstanding casting quality during the trials.