Ceramics-Silikáty 56 (4) 360-366 (2012)

TOUGHENING MECHANISMS OF Al₂O₃–SiO₂–ZrO₂ COMPOSITE MATERIALS

G. M. Asmelash, O. Mamat, F. Ahmad

In this paper, Al₂O₃–SiO₂–ZrO₂ (ASZ) composite was developed via pressureless sintering route and investigated for microstructures and mechanical properties. The flexural strength and fracture toughness of the SiO₂ + ZrO₂ particles reinforced alumina matrix was developed and measured 230.39 MPa and 2.39 MPa.m^1/2, respectively, demonstrating a significant tougheners due to the presence of both particles. The microstructural observation on cracked and fractured samples showed that three toughening mechanisms, crack deflection, crack bridging and microcracks were the contributing factors for the enhanced toughness of the matrix and the composite. Besides, phase transformation toughening and residual stress due to difference of coefficient of thermal expansion played a key role for the improved toughness of the composites.

Keywords: Flexural strength, Fracture toughness, Pressureless sintering, Residual stress