Enhancement of strength and thermal shock resistance of MgO-MgAl2O4 ceramic filters with microporous MgO powder: Effect of α-Al2O3 micro-powder content

Abstract

In this work, MgO-MgAl₂O₄ ceramic filters were fabricated from microporous MgO powder and α-Al₂O₃ micro-powder, in which microporous MgO powder was prepared using Mg(OH)₂ as initial raw material. With the α-Al₂O₃ micro-powder content increased from 0 to 15 wt%, the tight packing and reaction sintering between MgO microparticles and Al₂O₃ microparticles promoted the formation and growth of magnesium aluminate spinel necks, reduced the apparent porosity of ceramic filter skeletons, decreased the pore size, and improved the strength of the filters. When the α-Al₂O₃ micro-powder content further raised to 20 wt%, the thermal mismatch between MgO microparticles and spinel microparticles caused a small amount of crack generation, which lowered the strength of the filter. Besides, after introducing the α-Al₂O₃ micro-powder, more spinel necks were produced due to a small amount of MgO solid dissolved in the spinel lattice during the thermal shock test, which enhanced the thermal shock resistance of the filters. When the α-Al₂O₃ micro-powder content was 15 wt%, the filter had excellent comprehensive performance, the bulk density and apparent porosity of the filter skeleton were 3.09 g/cm³ and 10.7%, and the compressive strength before and after thermal shock test was 3.48 and 3.70 MPa, respectively.