| 摘要 |
Methods of preparing d dense and strong polycrystalline .beta."-alumina-containing ceramic body exhibiting an electrical resistivity for sodium ion conduction at 300.degree.C of 9 ohm-cm or lower obtained directly after sintering and a controlled fine microstructure exhibiting a uniform grain size under 50 micrometers. The invention more particularly relates to methods of uniformly distributing selected metal ions having a valence not greater than 2, e.g. lithium or magnesium, uniformly throughout the beta-type alumina composition to be sintered to form .beta."-alumina. This uniform distribution allows more complete conversion of .beta.-alumina to .beta."-alumina during sintering. As a result, the polycrystalline .beta." - alumina -containing ceramic bodies obtained by the methods of this invention exhibit high density, low porosity high strength, fine grain size (i.e. no grains over 25-50 micrometers with an average size under 5-10 micrometers), low electrical resistivity and a high resistance to degradation by water vapor in an ambient atmosphere.- The invention herein described was made in the course of or under a contract or subcontract thereunder with the National Science Foundation. |
