Upgrading superplastic deformation performance of fine-grained alumina by graphite particles

The process of ceramic part forming is often accompanied by grain growth, which in turn limits the deformation capabilities. Alumina ceramics are not usually good candidates for superplasticity as the grain growth reduces quickly their deformation performance. In order to impede the grain boundary mobility and to limit the grain growth, zirconia has often been associated with the alumina since the early 80s. In this work, a dense MgO-doped alpha-alumina containing a small amount of carbon has been produced. The sintering and the deformation behaviour of this material are compared to those of a MgO-doped alumina. The presence of small carbon particles reduces greatly the grain growth during the sintering and during the compression experiments. The superplasticity of the carbon-containing alumina is greatly improved. (C) 1999 Elsevier Science Limited and Techna S.r.l. All rights reserved.