Sodium Silicate as a Green Strength-Enhancing Component in Model Clay-Bauxite Refractories

摘要

The use of small concentrations of sodium silicate as a green strength-enhancing agent in model refractory compositions involving a Trinidad clay and a Guyana calcined bauxite has been investigated. The consequential "side effects" of the sodium silicate on fired body characteristics have also been studied. Dissolved in the water used (13%) for moulding, the sodium silicate concentration covered the range 0-0.94 g/mil. Two different clay-bauxite mixes were investigated: one containing 5% clay, the other 10% clay. Compared to the friable nature of the moulded test pieces when no sodium silicate was used in the mixing water, increasing concentrations of sodium silicate resulted in increased green strength (modulus of rupture), culminating in near-optimum at a sodium silicate concentration of about 0.63 g/mil. However, drying shrinkage increased slightly with increasing concentration of sodium silicate. As with green strength, fired strength (at 1100℃), particularly for the clay-bauxite composition containing 10% clay, also increased considerably with increasing sodium silicate concentration up to about 0.5 g/mil. This increase, however, was accompanied by a significant reduction in porosity compared to that exhibited by the "blank" samples in which no sodium silicate was used.