A Methodology for Estimating the Mechanical Properties of Oxides at High Temperatures

There are few data regarding the temperature dependence of elastic and related properties of materials. This paper describes a semiquantitative basis for estimating such properties in oxide materials to temperatures even approaching their melting points. The various elastic constants are shown to correlate with the field strength of the cationic species, and on V _o, the apparent atomic volume of oxygen. The value of V _o is readily determined from crystallographic data. High-temperature diamond pyramid hardness measurements are shown to correlate with V _o and to provide additional information regarding the structural stability of materials at high temperature. The various refractory oxides are analyzed using these approaches, allowing identification of oxides that appear to be exceptionally strong, stiff, and creep resistant at high temperature.