MECHANICAL RESPONSE ANISOTROPY IN HOT-PRESSED SILICON CARBIDE

摘要

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 hot-pressed SiC tile. Fracture was anisotropic (rather, transversely isotropic) but yield-like processes were isotropic. Flexure strength and fracture toughness were 23% and 10% lower, respectively, when the tensile loading direction was parallel to the hot-pressing axis. Hardness was isotropic and the responses from spherical indentation were different but inconclusive.