SEDL / STP / STP1207-EB / STP13739S

Impact Testing of Al²O³ and SiC^w/Al²O³ Ceramics

Deobald, LR
Senior specialist engineer, Boeing Defense and Space Group, Seattle, WA

Kobayashi, AS
Boeing Pennell Professor in Structure Mechanics, University of Washington, Seattle, WA

Pages: 10    Published: Jan 1994

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Abstract

A bar impact test procedure was used to study spallation of Al²O³ bars and dynamic fracture of Al²O³ and SiC^w/Al²O³ bars. Fractography analysis of the spalled surface showed extensive intergranular fracture (90 to 95% area). Dynamic fracture studies of precracked Al²O³ and SiC^w/Al²O³ bars showed that the dynamic initiation fracture toughness, K^Id, and the crack branching stress intensity factor, K^Ib, remained constant with increased impact velocity, that is, impact stress. Despite the increase in static fracture toughness, K^Ic with the addition of SiC whiskers in A1²O³ matrix, K^Ids and K^Ibs of Al²O³ and SiC^w/Al²O³ were about the same, suggesting that the SiC whiskers are not effective in dynamic fracture.