The effect of alumina content on fracture property of all-ceramics zirconia

Abstract

The purpose of the present study was to evaluate the effect of Al₂O₃ content on the fracture property of all-ceramics ZrO₂. To improve the all-ceramics ZrO₂ restoration mechanics properity,96 samples containing 0,5,10 and 15 wt% of Al₂O₃ particles were prepared by cold isostatic pressing (200 MPa) and 1 550 °C sintered. The phase was analyzed by X-ray diffraction analysis and the bulk densities of the samples were made using Archimedes principle. Samples were randomly divided into four groups. In each group, 24 specimens were prepared so that the angle between notch and specimen’s long axis is 90° and 60°. Notch depths were 1 mm for all samples. Samples were loaded with three-point bending method. 90° cut samples were used to measure fracture toughness while 60°cut samples were used to observe fracture curve by taking points on the fracture extension path under microscope, plotting points on coordinates, generating fitting curve by software “Origin”, and analyzing the microstructure of the specimen fracture surfaces by scanning electron microscopy (SEM).The results show that the increment of Al₂O₃ has insignificant effect on the densification of all-ceramic ZrO₂.XRD analysis shows that the specimen is comprised of t-ZrO₂ and α-Al₂O₃ before fracture while fracture surface is m-ZrO₂, t-ZrO₂ and α-Al₂O₃. ZrO₂ containing 10% Al₂O₃ has the optimum mechanical properties and unconspicuous crack propagation and distribution. The observations may provide a reference for the materials selection, shape design, and production process of all-ceramic crown and bridge.

Keywords

ZrO₂;Al₂O₃ / all-ceramics / notch / fracture load / fracture curve / microstructure

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