Evaluating the mechanical integrity and reliability of multi-channelled flat-sheet ceramic membranes for filtration applications

Ceramic membranes represent an emergent filtration technology that is receiving increasing research attention, particularly concerning their filtration behaviour (i.e., permeability, selectivity, and fouling) and industrial scalability. Given the inherent brittleness of ceramic materials, mechanical properties of ceramic membranes, especially those related to fracture, are also important pieces of information although nonetheless rarely evaluated. Therefore, a methodological approach for assessing the mechanical integrity and reliability of multichannelled flat-sheet ceramic membranes is presented here. Specifically, a flat-sheet SiC ceramic membrane designed for submerged outside-inside vacuum-driven filtration was subjected to four-point bending, tensile, and compressive tests, and the experimentally measured failure loads were converted to failure stresses and analysed by Weibull diagrams. It was found that the ceramic membrane is -1.4 times stronger and -2.9 times less reliable in compression than in bending, and -3.3 times stronger and -5.4 times more reliable in bending than in tension. These differences in mechanical integrity and reliability are rationalized by considering the fracture modes (i.e., modes I or II) and critical flaw populations (i.e., flaws of the membrane layer or support) responsible for failure. Finally, relevant implications for ceramic "membranologists" interested in mechanical characterisation are discussed.