Accession Number : AD0413994

Title :   MICROSTRUCTURE STUDIES OF POLYCRYSTALLINE REFRACTORY OXIDES.

Descriptive Note : Summary technical rept., 12 June 62-12 June 63,

Corporate Author : AVCO CORP WILMINGTON MASS RESEARCH AND ADVANCED DEVELOPMENT DIV

Personal Author(s) : Mitchell,J.B. ; Spriggs,R.M. ; Vasilos,T.

Report Date : 07 AUG 1963

Pagination or Media Count : 46

Abstract : The elastic modulus and transverse bend strength of pure, dense alumina and magnesia specimens were determined as a function of grain size (1 to 250 microns) and temperature over the range of 30 to 1500 C. The elastic modulus of both com pounds was found to be essentially independent of grain size over the temperature range covered. The transverse bend strength of fine-grain-size alumina was found to be substantially greater than larger-grain-size alumina over the entire temperature range although, at the highest temperatures, the rate of decrease of strength with temperature was greatest for the fine-grain material. The transverse bend strength of magnesia was less dependent on grain size than the alumina; and, in addition, this dependence showed further decreases with temperature. At higher temperatures, the larger-grain-size speci mens exhibited greater strengths than the fine grain magnesia. (Author)

Descriptors :   (*REFRACTORY MATERIALS, MECHANICAL PROPERTIES), (*ALUMINUM COMPOUNDS, OXIDES), (*MAGNESIUM COMPOUNDS, OXIDES), HIGH TEMPERATURE RESEARCH, MICROSTRUCTURE, CERAMIC MATERIALS, DENSITY, PORISITY, GRAIN, CRYSTALS, FRACTURE, FRACTOGRAPHY, ELASTIC PROPERTIES, CRYSTAL, LOADING (MECHANICS), DEFLEC, CREEP.

Distribution Statement : APPROVED FOR PUBLIC RELEASE