Mechanical properties of porous MgO substrates for membrane applications

Advanced design concepts for the application of oxygen transport ceramic membranes are based on thin layers supported by porous substrates. One suitable support material in this respect is porous MgO. However, a careful consideration of the mechanical stability is required to warrant long term performance and reliability under application relevant thermo-mechanical loads. The current work summarizes the effect of the sintering conditions on porosity and mechanical properties and gives elastic modulus and fracture stress as a function of temperature. An enhancement of the strength by the addition of boehmite to MgO was tested. Elastic moduli are determined and compared as obtained by indentation and bending tests. With respect to fracture, specimens in planar geometry are investigated using ring-on-ring bending tests; tubes are tested using an O-ring set-up. Fracture stresses are statistically analyzed. The obtained mechanical parameters are compared to that of other potential porous substrate materials.