No abstract

Several silicate-based materials were subjected to high pressure loading using spherical indentation, diamond anvil cell (DAC) testing, and laser shock impact. The test methods were chosen because they can apply many gigapascal (GPa) of pressure, are relatively quick and inexpensive to experimentally conduct, produce repeatable results, induce a bulk material response, and enable in-situ or postmortem material analysis. Differences in apparent yield stress, hydrostatic pressure, and laser shock responses were observed among the materials and are described herein.

Property anisotropy can exist in sintered ceramics and composites formed by pressure-assistance. Being that hot-pressed silicon carbide (SiC) is a utilized armor ceramic, and its fracture and damage multiaxially occurs in a ballistic impact, interest exists to measure the quasi-static mechanical (fracture and indentation) responses as a function of orientation to identify anisotropy. Flexure strength, fracture toughness, Knoop hardness, and spherical indentation were studied as a function of orientation with respect to the pressing axis in a 40-mm-thick hotpressed SiC tile. Flexure strength and fracture toughness were ~ 25% and 10% lower, respectively, in the plane perpendicular to the pressing axis while hardness was isotropic and the responses from spherical indentation were different but inconclusive.