Compressive strength, hardness and fracture toughness of Al2O3 whiskers reinforced ZTA and ATZ nanocomposites: Weibull analysis

The aim of this investigation was to study the variability in compressive strength, fracture toughness and microhardness applying the well-known Weibull statistics and to be able to provide a wide spectrum of mechanical properties in Al2O3 whisker reinforced alumina toughened zirconia (ATZ) and zirconia toughened alumina (ZTA) nanocomposites for possible dental applications. Uniaxial compression tests at room temperature of samples 6.35 ± 0.03 mm in diameter and 12.50 ± 0.63 mm in length and Vickers hardness measurements on polished surfaces were carried out. The indentation fracture toughness (KIC) was derived from the average crack length. Weibull analysis was performed on the data. The ATZ2 (18.0 wt.% Al2O3 + 2.0 wt.%(w) + 80.0 wt.% ZrO2 (TZ-3Y)) nanocomposite reported the highest average compressive load of 1200 MPa, the highest value of characteristic strength, σo, of 1340 MPa with Weibull modulus of 3.25 and relatively high fracture toughness (4.7 ± 0.7 MPa m1/2), suggesting that with the wide range of mechanical properties obtained in our work, different dental applications could be offered without lead to premature failure.

Research Highlights
► > 2 wt.% Al2O3 whiskers are required to get high fracture toughness in ATZ composites.
► Mechanical properties for dental use could be offered without premature failure.
► The matrix grain size dominates the compressive strength of ATZ and ZTA composites.
► Crack deflection and the aspect ratio of whiskers improved the mechanical properties.