engleski

Fracture toughness of alumina ceramics determined by Vickers indentation technique

Fracture toughness (KIC) of high purity cold isostatically pressed alumina (CIP-Al2O3) was determined from the size of cracks induced by Vickers hardness testing at the wide range of loads. The observed cracks appeared at following loads: 4.905 N, 9.81 N, 29.43 N and 49.05 N. The studied material exhibits half- penny crack system at lower load of 4.905 N, but it proceeds as the Palmqvist crack system at higher loads, which was determined computationally. For the fracture toughness calculation different models were compared. It was found that fracture toughness increases by increasing applied load for all applied models, which is explained by the indentation size effect. As the fracture toughness overestimation can lead to product malfunction, it is suggested to use the Niihara model, which gives the smallest fracture toughness values.

fracture toughness ; alumina ceramics ; Vickers hardness ; indentation technique

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