| Popis: |
It is well known that the effective thermal conductivity of bonded molding sands depends on the volume fraction, thermal conductivity and arrangement of the components e.g., sand particles, bonding medium and air. The arrangement of components is known to be affected by particle size distribution, average size and shape. In this study, an experimental system using the line-heat-source method was designed and effective thermal conductivities of molding sands at temperatures up to 750°C were measured. The effects of binder content, initial moisture content, dry density and temperature were also investigated for four selected sand types: silica, olovine, zircon and chromite sands. The effect of dry density on the effective thermal conductivity of bintonite-bonded molding sands turned out to be more significant than the effect of either binder content or initial moisture content. The minimum effective thermal conductivity for bentonite bonded silica sand occurred at about 500°C. The effective thermal conductivity of silica sands bonded with western bentonite was found to be higher than that of silica sands bonded with southern bentonite up to 750°C. |
