HIGH-TEMPERATURE EXTRUSION BEHAVIOR OF A SUPERPLASTIC ZIRCONIA-BASED CERAMIC

Workability of 3‐mol%‐yttria‐stabilized tetragonal ZrO2 has been gauged through a series of extrusion experiments performed under vacuum with graphite dies at 1500°C and 35 MPa piston stress. It is shown that dense and smooth extrusions can be obtained from solid billets when graphite paper is used as a lubricant. Sigmoidal dies and conical dies with cone angles of 18.4°, 26.6°, and 45° and diameter ratios of 1.5, 2, and 3 were used to explore extrusion behavior. Observed piston velocities correspond to what may be predicted from the experimental uniaxial constitutive creep equation and a simple slab analysis. A precise analysis, however, is not attempted because of lack of steady‐state behavior of the material itself. Copyright © 1990, Wiley Blackwell. All rights reserved