Effect of TiO₂ addition on microstructure and strength of porous spinel (MgAl₂O₄) ceramics prepared from magnesite and Al(OH)₃

Highlights: • Porous spinel (MgAl₂O₄) ceramics were prepared from magnesite and Al(OH)₃ with TiO₂ addition. • The amount of TiO₂ added (ATA) affected the formation of liquid phase at sintering temperature. • The optimized product is a specimen with 1.5 wt% ATA which has high apparent porosity and strength. - Abstract: Porous spinel (MgAl₂O₄) ceramics were prepared from magnesite and Al(OH)₃ with TiO₂ addition through an in-situ decomposition pore-forming technique. The porous ceramics were characterized through X-ray diffractometer (XRD), scanning electron microscopy (SEM), and mercury porosimetry measurements, etc. The effect of TiO₂ addition on the phase compositions, pore characterizations and strengths was investigated. The results showed that the amount of TiO₂ added (ATA) affected the formation of liquid phase at sintering temperature, changed the porosity, the pore size distribution and the neck bonds, thus affecting the strength of the porous ceramics. With an increase in ATA, the liquid content at sintering temperature increased, the neck bonds developed better, the porosity decreased, and the average pore size and strength increased. The optimized product is a specimen with 1.5 wt% ATA which has a high apparent porosity (53.0%), a small average pore size (5.95 μm), a high compressive strength (21.2 MPa), a high flexural strength (8.5 MPa) and a relatively homogeneous pore size distribution