Influence of the inclusion shape on thermal stresses in a cubic ZrO2-Al2O3composites
Mirosław M. Bućko, Waldemar Pyda, Grzegorz Grabowski, Zbigniew Pędzich Akademia Górniczo-Hutnicza, Wydział Inżynierii Materiałowej i Ceramiki, al. Mickiewicza 30, 30-059 Kraków
Quarterly No. 3, 2006 pages 59-64
DOI:
keywords: particulate composite, cubic zirconia, alumina, thermal stress, reinforcement
abstract Classification of inclusions for cubic zirconia-alumina composites was made using the shape criterion (Fig. 1). Two classes were selected: (i) convex inclusions, (ii) inclusions with variable positive or negative curvature. Mechanisms responsible for the inclusion formation with the classified shape were indicated. Among other things it was the mechanism related to the particle shape of initial alumina powder (Fig. 2). Influence of the inclusion shape on crack propagation was assessed by determination of thermal stress distribution caused by thermal expansion coefficient mismatch between zirconia matrix and alumina inclusion. The finite element method was used. The stress distribution in the system isolated inclusion - cubic zirconia matrix was analysed (Fig. 3). It was found that the value of tensile stress in the matrix as well as of compressive stress in the inclusion were affected by an interface curvature (Figs. 4 and 5). The positive curvatures (convex interfaces) led to an increase of the tensile stress in the matrix whereas the negative curvatures (concave interfaces) led to a decrease of the compressive stress in the inclusion. The relationship between crack propagation (Fig. 6) and the decrease of the compressive stress in the inclusion was stated. Influence of the alumina inclusion shape on fracture toughness of the cubic zirconia-alumina composites was considered.