Fabrication and characterization of macroporous alumina -nano tetragonal zirconia -nano spinel ceramic composites

Abstract

In order to protect the environment, waste materials like bagasse have recently been recycled in the production of porous ceramics. For the synthesis of nano tetragonal zirconia (t-ZrO2) and nano spinel (MgAl2O4), a modified co-precipitation method is used. The phase composition, particle size, and surface area of the synthesized nanoparticles were examined using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM- TEM), and Brunauer-Emmett-Teller (BET) analyses, respectively. To prepare alumina – nano t-ZrO2 –nano spinel macroporous ceramics, nano t-ZrO2 was added from 0 to 30 wt% at the expense of nano spinel to calcined alumina (70 wt%). Bagasse ash (as a pore-forming agent) was added to the mixed compositions in weight percentages ranging from 0 to 15 wt%. All prepared samples were sintered at different temperatures (1350, 1450, and 1450 °C). The influence of nano t-ZrO2, bagasse ash, and sintering temperature on the phase composition, densification parameters, cold crushing strength (CCS), microstructure, and the distribution of pores in sintered samples was looked into. According to the results, the major phases observed in sintered samples are corundum, spinel, tetragonal zirconia, and monoclinic zirconia phase. The cold crushing strength of sintered samples increased with increasing nano tetragonal zirconia additions due to the tetragonal to the monoclinic toughening mechanism of t-zirconia. With increasing bagasse additions, the bulk density decreased from 2.66 g/cm3 to 1.49 g/cm3, while the apparent porosity increased from 30.2% to 56.04%. The microstructures and pore size distribution of the sintered samples show that the prepared porous ceramic samples have high crystallinity, with an average pore size between 2.51 μm and 3.32 μm.