CYCLIC FATIGUE-CRACK PROPAGATION IN SIC-WHISKER-REINFORCED Y-TZP COMPOSITES

The ambient-tenperature subcritical growth behaviour of SiC-whisker-re inforced yttria-stabilized zirconia (SiCw/3Y-TZP) ceramic composites i s investigated during cyclic fatigue loading. Based on long-crack expe riments using few-point bending specimens, cyclic fatigue crack growth rates (over the range 10(-10) to 10(-5)(m/cycle)) are found to be sen sitive to the maximum stress intensity factor and loan ratio. Similar to other ceramic materials, the long crack fatigue threshold, Delta K- TH, is found to be of the order of 45% of K-lc, and enhanced with incr easing fracture toughness. A unique growth law strongly dependent on t he K-max and modestly on Delta K is established. Possible mechanisms f or cyclic crack growth in whisker-reinforced zirconia composite materi als are discussed. (C) 1997 Elsevier Science Limited.