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An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBA2CU307 ceramics with optimum properties. The process employed YBA2CU307 powders dispersed in organic carrier liquids and foundry molds developed at, and patented by LaRC. The slips were poured into the molds as in traditional slip casting operations, however, instead of removing the casting from the mold, the molds were destroyed, leaving a cast ceramic shape. The most reliable organic carrier for the YBA2CU307 powder was found to be an acetone/menhaden fish oil system.

The analysis of variance results indicate that careful control of the various casting variables is critical in controlling both the density and porosity of cast YBA2CU307 ceramics. As density and porosity are indications of the current carrying capacity of the superconductor, the optimization of the critical process parameters to produce superconductors with both high densities as well as a porous network permitting the uniform uptake of oxygen throughout the cast superconductor, is of great importance.

These results indicate that the properties of cast superconductors may be controlled by understanding the effects of traditional ceramic processing variables such as the particle size distribution of the cast powders and the sintering temperature, as well as their interaction.

This work was cited in the August and September 1992 issues of the American Ceramic Society Bulletin. The NASA-Langley Research Center contacts are S.A. Wise and M.W. Hooker, telephone number (757) 864-8068. A full report of this process is contained in the paper "Effects of Process Variables on the Properties of YBA2CU3O7-X Ceramics Formed by Investment Casting", authored by M.W. Hooker, T.D. Taylor, and H.D. Leigh, Department of Ceramic engineering, Clemson University, Clemson, SC 29634-0907; and S.A. Wise, J.D. Buckley, P. Vasquez, G.M. Buch, and L. P. Hicks, NASA-Langley Research Center, Hampton, VA 23681