Fracture Energy and Strength Behavior of a Sodium-Borosilicate Glass-Al2O3 Composite System
WESTINGHOUSE RESEARCH LABS PITTSBURGH PA PITTSBURGH United States
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A significant increase in fracture energy was observed up to 5 times the fracture energy of the glass without a second phase dispersion. The fracture energy depended on both the interparticle spacing and average particle size of the Al2O3 dispersion. These results could best be explained by a previously proposed model for the interaction of a crack front with a second phase dispersion. Surface roughness also contributed to the increased fraction energy. Some composites exhibited a significant strengthening relative to the glass without a dispersion. Calculated values of the crack size showed that the Al2O3 dispersion increased the crack size of the glass by an amount equal to about 1-3 times the average particle size of the Al2O3 dispersion. Thus, the Al2O3 dispersion increased both the fracture energy and the crack size. These two opposing parameters ultimately determined the strength behavior of these composites.