Particle Impact Damage in Ceramics.
Abstract
Impacts of tungsten carbide spheres on Si3N4 produced elastic fracture behavior (ring and cone cracks) at room temperature, but elastic-plastic fracture behavior (plastic impressions and radial cracks) at 1400 C. In contrast, no change in fracture pattern at the two temperatures was produced by impact with steel spheres. These results may be explained by the relative abilities of the impacting spheres to cause plastic flow at the impact site and hence to alter the stress distribution in the Si3N4 specimens. The type and extent of damage produced by hard particle impact at 1400 C appears to be more deleterious to structural integrity than that produced at 20 C under equivalent particle impact loading conditions. When impacted by 1.2-mm-diameter tungsten carbide spheres at velocities to 200 m/s, oxidized Si3N4-20 vol% ZrO2 exhibited decidedly less fracture damage than unoxidized material. The impact velocity necessary to initiate ring and radial cracks was significantly higher for oxidized materials, and the rate at which fracture damage, once nucleated, developed was substantially lower. This enhanced dynamic performance is consistent with the enhanced quasi-static properties reported by Lange and may involve oxidation-induced compressive surface stresses, oxidation-induced softening, or both. Progress is reported in the development of a predictive capability for fracture damage produced by particle impact.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1981
- Accession Number
- ADA097982
Entities
People
- D. A. Shockey
- D. C. Erlich
- Damian Curran
- K. C. Dao
- R. L. Burback
Organizations
- SRI International