COMPOSITION OF CERAMIC INVESTMENTS FOR LOST-WAX CASTINGS.

Investments consist of assemblages of granular material from the dusting powder and the slurry, bonded by films of silicic acid derived from ethyl silicate, and their overall chemical composition provides no information on the properties of original molding materials they contain. A special procedure has been developed to determine the proportions of each component and estimate the variability of investment quality. The new procedure for determining the constitution of investments made with disthene-sillimanite and corundum bonded with ethyl silicate facilitated the stabilization of process conditions and provided data on the effects of individual factors on constitution and quality. In every specific case, it was possible to correlate the quality of the investments with the quantitative constitution of the refractory.