Accession Number : AD0719910

Title :   Exfoliation and the Mechanical Behavior of Scales,

Corporate Author : CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s) : Douglass,D. L.

Report Date : FEB 1971

Pagination or Media Count : 35

Abstract : Strains exist in oxide films due to volume mismatch, adherency, epitaxy, etc. and often cause stresses that exceed the fracture stress of the scale. Fracture may lead to exfoliation which then exposes fresh metal and enhances the oxidation process. Even if strain-free scales form during isothermal oxidation, subsequent cooling and reheating may create strains due to differential thermal dilation of the oxide and metal. Strains may be relieved by plastic deformation of either the scale or the substrate, although in many cases the scales are not plastic. The mechanical properties and behavior of scales determine primarily if they remain intact and provide their intended protection. All of the factors involved in film fracture and exfoliation, including both short-time and time-dependent deformation, are considered with respect to film spalling. (Author)

Descriptors :   (*METALS, SCALE), FILMS, DEFORMATION, FRACTURE(MECHANICS), OXIDATION, STRESSES

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE