Accession Number : AD0611813

Title :   DIFFUSION STUDIES IN REFRACTORY MATERIALS.

Descriptive Note : Summary rept. for 1 Mar 64-28 Feb 65,

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

Personal Author(s) : Wuensch,B. J. ; Vasilos,T.

Report Date : 28 FEB 1965

Pagination or Media Count : 20

Abstract : Progress is reported in a program to investigate the effects of imposed stress and also the presence of grain boundaries on diffusion rates in magnesium oxide is described. Loads of up to 5000 psi on samples placed in four-point loading do not appear to influence the rate of diffusion of Ni(2+) in single-crystal MgO in the temperature 1000 - 1300C. Grain boundary diffusion of Ni(2+) and Co(2+) has been observed in isolated grain-boundaries in MgO bicrystals. The effect appears to be due to segregation of impurities, principally Ca(2+) and Si(4+), at the boundary, and is not an intrinsic property of the grain boundary. Data for the diffusion of Zn(2+) in MgO have been obtained, and may be described in terms of an activation energy of 1.85 electron volts and a value of D sub o of 0.0000148 sq cm/sec. (Author)

Descriptors :   (*CERAMIC MATERIALS, DIFFUSION), (*REFRACTORY MATERIALS, DIFFUSION), (*DIFFUSION, REFRACTORY MATERIALS), (*MAGNESIUM COMPOUNDS, OXIDES), MONOXIDES, SINGLE CRYSTALS, GRAIN BOUNDARIES, NICKEL, COBALT, CRYSTALS, IMPURITIES, CALCIUM, SILICON, ZINC, HEAT OF ACTIVATION, DIFFUSION BONDING, CRYSTAL LATTICES

Distribution Statement : APPROVED FOR PUBLIC RELEASE