Investigation of reinforcement of porous alumina by nickel aluminate spinel for its use as ceramic membrane

This paper reports the reinforcement of porous alumina ceramics by forming nickel aluminate spinel phase in an alumina matrix via the reaction between nickel (II) oxide and alumina. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, three-point bending test and mercury porosimetry were used to characterise the porous ceramic samples. The highest bending strength of 146 MPa was achieved in the porous alumina with 14.7 wt% NiAl2O4 and a porosity of 30.5%. A decrease in bending strength and increase in porosity was observed in porous alumina with over 14.7 wt% NiAl2O4. The appreciable bending strength and porosity made NiAl2O4 reinforcement a promising method for fabricating ceramic membranes with improved toughness in different geometries including hollow fibre membranes.