The Synthesis, Processing, Deformation and Failure of Superplastic Nanocrystalline Ceramic Composites
Abstract
Commercially available nanocrystalline 3 mol% yttria stabilized tetragonal zirconia powders with a crystallite size of < 40 nm were processed using a colloidal technique. Essentially, the powders were dispersed in de-ionized water, and the pH of the solution was adjusted to approx. 2 to disperse the powders. The solution was ultrasonicated and then pressure filtered to produce a green body with a relative density of approx. 50%. The densification and grain growth characteristics of zirconia were examined during the free sintering and sinter-forging (sintering with the application of a compressive uniaxial stress without any lateral constraints) at temperatures in the range of approx. 1600 to 1750 K. It was demonstrated that it is possible to produce fully dense compacts with a grain size of approx. 175 nm using this technique. During sinter-forging, both densification and creep processes occur simultaneously; the measurement of density and axial strain enable to separation of the kinetics of the two processes. It was shown that deformation during densification occurs by an identical process as in fully dense materials (mainly grain boundary sliding). Furthermore, the differences in the stress exponents for creep and densification indicated that densification was not controlled directly by deformation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 14, 1999
- Accession Number
- ADA371595
Entities
People
- Atul H. Chokshi
- Vikram Jayaram
Organizations
- Indian Institute of Science, Bengaluru