Mechanical characterization of micro- and nano-porous alumina

Advanced membrane concepts are based on thin layers that require a mechanically robust porous substrate material. Aiming at the use in precombustion systems, alumina substrate with different pore sizes were characterized with respect to their mechanical properties. Elastic moduli and fracture stresses were assessed using ring-on-ring bending tests. Furthermore, elastic moduli were compared to data obtained from indentation tests. Although porosity of the micro- and nano-porous materials were equal, elastic moduli and fracture stress values revealed significant differences, indicating that based on mechanical considerations the nano-porous material is far superior, although initial permeation test indicate difficulties in using it as porous substrate. Elastic moduli showed good agreement with a model based on the load-bearing contact area. Microstructural investigations supported that the higher strength of the nano-porous material is a result of a larger contact area between grains. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.