R-curve and controlled stable crack growth behaviour of ZrB 2 –17vol.-%SiC and ZrB 2 –45vol.-%SiC ceramic composites was studied on V-notched samples using four-point bending at room temperature. The rising K 1R behaviour was determined as a function of the crack extension Δa with a crack bridging mechanism being dominant in such behaviour. Significant differences in crack growth rates were found within the same composition of ceramics simply as the crack length varied during crack growth processes. These differences are indicative of the significant influence of microstructural parameters of the ceramics on crack propagation. The peculiarities of stress intensity factor K 1 and the crack growth-specific behaviour in ZrB 2 –SiC particulate ceramic composites are discussed.
