Superplastic forming of a zirconia ceramic sheet

Technical understanding of ceramic superplasticity has advanced to the point that superplastic forming of net-shaped articles may now be considered as a viable ceramic processing technique. In this paper, a method is demonstrated for the gas pressure forming of yttria-stabilized tetragonal zirconia sheet. Hemispherical caps were superplastically formed from flat discs in the temperature range of 1,450 C to 1,600 C using applied forming pressures in the range of 375 kPa to 2,760 kPa. True strain rates as great as 0.01 s-1 were achieved. Deformation behavior under the biaxial forming conditions of this study closely agrees with behavior observed under uniaxial tension conditions in previous studies. The forming experiments have been extended to include net-shaped forming and metal-ceramic bonding and codeformation. Also discussed is the role of grain growth during deformation, and the strain distribution in formed articles