Room temperature R-curve and stable crack growth behaviour of ZrB₂–SiC ceramic composites

ABSTRACT

R-curve and controlled stable crack growth behaviour of ZrB₂–17vol.-%SiC and ZrB₂–45vol.-%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 K₁ and the crack growth-specific behaviour in ZrB₂–SiC particulate ceramic composites are discussed.

KEYWORDS:

• ZrB₂–SiC ceramic composite
• bridging
• crack growth
• R-curve

Acknowledgement

We thank the graduate student Jannik Krivohlavek for valuable help and machine operation during the R-curve measurement experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Dr. Orlovskaya’s and Dr. Lugovy’s work was in part supported by the NSF, the Division of Materials Research, project #1337758. Dr. Lugovy’s work at Empa was supported by Swiss National Science Foundation via the International Short Visit fellowship (decision IZK0Z2_134265). Mr. M. Neumann was supported by Empa, Laboratory for High Performance Ceramics internal grant for BSc/MSc student research.