Design of Superplastic Ceramics

University Of California-Irvine, Irvine CA

Investigators

Abstract

The optimal microstructural design of superplastic ceramics using finely dispersed second phases will be studied. Intergranular silicate phases and nanodispersed crystalline oxides will be used to create ceramic materials with improved properties for shape forming via superplastic deformation. The volume and distribution of second phases and their interfacial energy and solubility will be variables analyzed with respect to grain growth, grain boundary sliding, and fracture in polycrystalline oxides. Experimental analysis techniques will include analytical electron microscopy and impedance spectroscopy as well as mechanical deformation tests both at room temperature and at high temperatures. The goal of this research is to understand how chemically dissimilar dispersants can be used at the nanoscale to tailor the mechanical properties of oxide ceramics, so that highly deformable ceramics can be net shape formed at high temperatures while retaining a superior mechanical and electrical performance at lower temperatures. Superplastic forming has the potential to allow the production of shapes not easily attained by conventional ceramic processing techniques. Superplastic deformation of ceramics currently, however, is currently possible only in a few limited ceramic systems that retain a fine grain microstructure. In addition, the extremely high temperatures required for this process and slow strain rates attained limit the industrial applications of this technique. This research will focus on optimizing the microstructural design parameters that will result in lower temperatures for superplastic forming and increased deformation rates while expanding the range of ceramic materials that can be shaped by superplastic forming, thus making this technique a more economically viable method for net shape forming of ceramics.