Fracture Toughness Estimation From Ceramic Tensile Specimens by Fractographic Analysis.
Final rept. Oct 94-Sep 96,
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
Pagination or Media Count:
Empirical criteria are presented for selection of uniaxial tensile failure origins that will yield valid fracture toughness estimations. Using these criteria, estimations of fracture toughness based on fractography of an AIN, two SiCs, a AIN-SiC solid solution and a particulate composite, and a TiB2 were performed. Comparison of the fracture toughness values estimated from fractography with fracture toughness measured by the single-edge precracked beam SEPB method will be shown. Close agreement is observed between estimates made from fractographic analysis and measurements made on specimens with large artificially induced flaws if the fracture toughness is 4 MPa square root of m or below. For materials in which the SEPB fracture toughness is greater than about 4.8 MPa square root of m, estimates by fractographic analysis significantly underestimate the SEPB fracture toughness. In attempting to rationalize this discrepancy, the importance of rigorously applying the empirical criteria was reemphasized.
- Ceramics, Refractories and Glass
- Fabrication Metallurgy