Mechanical Properties of Magnesia–Spinel Composites

The mechanical properties of magnesia–spinel composite ceramics, which are candidate materials for supporting solid oxide fuel
cells, have been measured as a function of porosity (up to 30%) and temperature (up to 9001C). The theory for the ring-on-ring test has been re-examined to resolve an inconsistency in the literature.
The Young’s modulus shows an exponential dependence on porosity that is in agreement with the expectation of minimum solid area models. Fracture toughness, fracture energy, and flexural strength are all approximately proportional to Young’s modulus.
The mechanical properties are not greatly dependent on temperature, but there is a detectable increase in fracture toughness with temperature, which could be due to some limited plasticity.