Fatigue in monolithic ceramics

Researcher: Nasrin Al-Nasiri

Supervisors: Dr Finn Giuliani, Dr Luc Vandeperre and Professor Eduardo Saiz

Funding: Centre for Advanced Structural Ceramics

Ceramic materials have excellent thermal and chemical stability and are slowly penetrating an increasing number of markets. For example, silicon carbide (SiC) is increasingly being used in scientific instruments for space and in satellites. The main problem of ceramics is their inherent brittleness which can lead to a catastrophic failure without any prior notice. In a recent study for the European Space Agency in collaboration with industry, it became apparent that fatigue in ceramics is an area that has not received sufficient attention to allow accounting for fatigue at the same level of maturity as for metals. This project is intended to widen the knowledge base in this area by furthering the understanding of known fatigue mechanisms in ceramics through a combination of in-situ testing and crack-tip tomography by reconstructing focused ion beam slices, widening the understanding of the importance of the characteristics of the fatigue cycle (e.g. the presence of compressive stresses or not) and establishing whether some ceramics are indeed free from fatigue effects.

The project only started recently. Achievements to date include the development of a rig capable of carrying out double cantilever beam testing (constant moment variant) in the SEM and initial work on FIB tomography of cracks.