Recycling bagasse and rice hulls ash as a pore‐forming agent in the fabrication of cordierite–spinel porous ceramics

Abstract

Bagasse and rice hulls ash are both waste materials. In recent years, in order to meet environmental protection, these materials have been recycled in the production of porous ceramics. A solid-state reaction mechanism of calcined alumina and talc was used to prepare cordierite-spinel porous ceramics. Talc was added from 30 to 60 wt.% at the expense of alumina and sintered at 1400 • C for 2 h. The effect of bagasse and rice hulls ash (as a pore forming agent) on the densification parameters, cold crushing strength (CCS), and pore size distribution was also studied. The phase composition (X-ray diffraction) and microstructure (scanning electron microscopy) of sintered samples were investigated. The results showed that the main phases present in the samples are cordierite, corundum, spinel, and sapphirine. In the sample with a higher amount of talc additions (60 wt.%), only the formation of the cordierite and spinel phases was observed. The bulk density of the samples and the apparent porosity ranged from 1.77 to 2.26 g/cm 3 and from 28.6% to 48.21%, respectively. The CCS of the samples ranges from 13.9 to 36.3 MPa. The microstructures of the sintered samples were observed for the formation of cordierite phase, alumina phase, and spinel phase in an excellent crystallization and phase arrangement.

Sintering and characterization of in situ formed porous cordierite ceramics with nano boehmite additions

“…It was observed that CCS is affected by various variables such as starting materials, preparation technique, and sintering temperature. In addition, the CCS of the samples decreases with decreasing bulk density 30,39,43–46 . Furthermore, the CCS, density, and porosity for our results were found to be in the same ranges as previous studies with the use of low‐cost, nontoxic, environment‐friendly materials with a simple and practical preparation technique.…”

“…Spinel was formed as an intermediate solid phase between the beginning oxides (MgO + Al 2 O 3 → MgAl 2 O 4 ) and the formation of cordierite. Some of it reacted with silica to form cordierite (2MgAl 2 O 4 + 5SiO 2 → Mg 2 Al 4 Si 5 O 18 ), whereas some remained as it is (as spinel phase) 30 . Moreover, some silica and alumina did not react and appeared as quartz and α‐alumina, respectively, in XRD patterns.…”

“…Porous ceramics can be prepared using pore‐forming agent method, 29,30 foam‐gel‐casting method, 1,31 and sol–gel method 32 . One of the widely used techniques for producing porous ceramics with regulated microstructure (porosity and pore size) is the use of pore‐forming agents 33 .…”

“…This can result in porous microstructure of alumina derived from pure boehmite sol if the sol does not seed even after being sintered for a long time (>6 h) at 1600 • C. The conversion of γto α-Al 2 O 3 is a slow process that occasionally results in a porous vermicular network; thus, α-Al 2 O 3 seeds are added to boehmite to shorten the conversion and densification processes. 28 Porous ceramics can be prepared using pore-forming agent method, 29,30 foam-gel-casting method, 1,31 and sol-gel method. 32 One of the widely used techniques for producing porous ceramics with regulated microstructure (porosity and pore size) is the use of pore-forming agents.…”

Modified carbon paste ion selective electrode for determining Cr(iii) ions in aqueous solutions and some real samples using tetragonal zirconia nanoparticles

“…The shape and microstructure of the surface of the prepared t-ZrO 2 nanoparticles were examined using scanning electron microscopy (SEM) in conjunction with EDAX, Digital Surf's Mountains Lab®, and Java 1.8.0172 with ImageJ (1.53e) soware. 46,47 SEM images of the t-ZrO 2 nanoparticles showed their spherical-like shape, homogeneous matrix, smooth surface, and porous structure (Fig. (2A)).…”