Abstract
Surface oxidation in metal matrix composites (MMC's) is modeled by Fickian diffusion of oxygen in both the oxide layer and metal matrix. The oxidation process and the resulting immobilized oxygen at the interface is accounted for by the introduction of a jump discontinuity in the oxygen concentration across the interface. The problem of a uniformly growing oxide layer from the surface of a semi-infinite solid, outward oxygen diffusion and oxidation from a cylindrical cavity, as well as inward oxygen diffusion and oxidation from surface of cylinder, are considered as benchmark problems in oxidation of MMCs. The closed form solution for the planar diffusion is obtained and is used for the comparison with a finite element formulation of the moving interface problem. In addition to the surface oxidation formulation, a one-way coupled thermomechanical analysis of a unidirectional SiC/Ti-15-3 composite undergoing simple tension is performed and the critical applied load for surface crack formation in the oxide layer is evaluated. A detailed stress analysis is made for this purpose by using a variational approach. In addition, thermomechanical testing and SEM analysis are being carried out for unidirectional laminates with Ti based matrix material and SiC fibers such as Sigma/Ti-15-3 and SCS-6/[]21s.
Ma, Xinzheng (1995). Modeling of surface oxidation and oxidation induced damage in metal matrix composites. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -M3.