Fracture toughness, surface flaw sizes and flaw densities in Al{sub 2}O{sub 3}
- Univ. of Leeds (United Kingdom)
Surface flaw sizes and flaw densities on polished dense polycrystalline alumina specimens with grain sizes G = 1.2, 3.8 and 14.1 {micro}m were measured using Hertzian indentation. Two surface finishes were studies: well-polished (Syton) and coarse-polished (45 {micro}m diamond paste). Flaw sizes and densities depended on the surface finish and increased with increasing grain size. Fine grained specimens exhibited a high density of small flaws while coarse grained specimens exhibited a higher density of larger flaws. Fracture toughness (K{sub lc}) for each material (relating to the propagation of flaws of a few {micro}m depth) was determined from the minimum fracture load in a series of Hertzian tests. K{sub lc} values were 3.58, 3.45 and 2.96 MPam{sup 1/2} for G = 1.2, 3.8 and 14.1 {micro}m, respectively. Fracture toughness values were also determined by Vickers indentation over a range of loads; the K{sub lc} values determined from the Hertzian tests were consistent with the trends in K{sub lc} with crack size from the Vickers indentation tests.
- Sponsoring Organization:
- Fundacao Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) (Brazil)
- OSTI ID:
- 483618
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 3 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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