EFFECT OF LOADING SPEED ON FRACTURE-BEHAVIOR OF ZRO2(AL2O3) MATRIX COMPOSITES REINFORCED WITH SIC WHISKERS

The fracture toughnesses, fracture behaviour and toughening mechanisms of 20 vol% SiCw-ZrO2 (2 mol% Y2O3), 20 vol% SiCw-ZrO2 (6 mol% Y2O3), 20% SiCw-Al2O3 and 20 vol% SiCw-20 vol% ZrO2 (2 mol% Y2O3)- Al2O3 comp osites (SiCw means SiC whisker) were investigated by three-point bendi ng tests, XRD and scanning electron microscopy techniques. The results show that the fracture toughnesses of the composite materials increas e with increasing loading speed because of the increase in the amount of dynamic t-->m ZrO2 transformation and whisker pullout effect. Whisk er/matrix characteristis have a significant influence on the effect of loading speed on the fracture behaviour. (C) 1998 Elsevier Science Li mited and Techna S.r.l.