Porous cordierite ceramics prepared by foam-gelcasting technique: Phase evolution and properties

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.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Wahsh

Mansour

Othman

et al. 2022

“…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 .…”

Section: Introductionmentioning

confidence: 99%

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

Mansour

Wahsh

Othman

2023

In this study, we investigated the effect of sintering temperature and nano boehmite additions on the phase composition, densification, and mechanical properties of porous cordierite ceramics. Ceramic samples were sintered at temperatures ranging from 1200 to 1400 • C. Carbon powder was used as a pore forming agent to improve the porosity of the ceramic structure. Nano boehmite and carbon additions significantly enhanced ceramic porosity and average pore size in sintered samples. The bulk density and apparent porosity of the sintered samples were found to be 0.96-1.53 g/cm 3 and 42.3%-65.6%, respectively. Sintered samples had cold crushing strengths of 1.5-14.3 MPa. The microstructure obtained by scanning electron microscopy was used to measure average pore size in sintered samples and was found to be 41.93 µm for stoichiometric composition (SC), 67.72 µm for SC and nano boehmite, and 102.98 µm for SC, nano boehmite, and carbon. The microstructure of the sintered samples revealed that the crystallinity of the in situ formed phases increased with the increase in nano boehmite additions.

“…Microporous MgO-Al 2 O 3 refractory aggregates can be obtained by crushing and sieving microporous MgO-Al 2 O 3 ceramics. [22][23][24][25][26][27][28][29] At present, many preparation methods of porous MgO-Al 2 O 3 ceramics with different pore structures have been proposed, such as foam-gelcasting, [30][31][32][33] template method 34 and direct forming. 35 For instance, Deng et al 31 prepared porous MgAl 2 O 4 ceramics with a porosity of 75.1% via a foam-gelcasting method but with the disadvantages of a large average pore size of 266 μm and a low compressive strength of 12.5 ± 0.8 MPa.…”

mentioning

confidence: 99%

“…Different from the above-mentioned preparation methods, [30][31][32][33][34][35] an in-situ decomposition pore-forming technique, which utilizes the decomposition of raw materials to form pores, is much simpler and more environmentally friendly leading to microporous ceramics with well-distributed pores. 29,36 For example, Li et al 37 prepared porous corundum-spinel ceramics with apparent porosities of about 70%-75% utilizing the decomposition of Al(OH) 3 and basic magnesium carbonate (4MgCO 3 •Mg(OH) 2 .5H 2 O) to form pores, but with the disadvantage of a very low strength.…”

mentioning

confidence: 99%

Microstructures and strengths of microporous MgO‐Al₂O₃ refractory aggregates using two types of magnesite

Chen

Yan

Dai

et al. 2020

Six microporous MgO-Al 2 O 3 refractory aggregates were prepared with Al(OH) 3 and two different types of magnesite powders via an in-situ decomposition pore-forming technique. One magnesite powder contained more CaO (Magnesite C), the other one contained more SiO 2 and Al 2 O 3 impurities (Magnesite SA). Effects of magnesite powder type and content (11 wt.%, 36 wt.% and 77 wt.%) on the phase compositions, microstructures and mechanical strengths of the prepared microporous aggregates were investigated by X-ray diffractometry (XRD), mercury porosimetry measurements, and scanning electron microscopy (SEM), etc. With the addition of 11 wt.% and 77 wt.% magnesite, the type of magnesite had only a small effect on the microporous corundum-spinel and periclase-spinel aggregates, while great influence on the microporous spinel aggregates was observed with 36 wt.% addition. This was mainly because of the sintering process with liquid phase. The best microporous MgO-Al 2 O 3 refractory aggregates, which had an apparent porosity of 39.1%, a median pore size of 3.38 μm and a compressive strength of 66.3 MPa, were prepared by using 36 wt.% Magnesite C. This work has practical significance for the efficient utilization of magnesite and the development of energy-saving lightweight MgO-Al 2 O 3 refractories. K E Y W O R D S in-situ decomposition pore-forming technique, magnesite powders, microporous MgO-Al 2 O 3 refractory aggregates, microstructures, properties Department of Education's Scientific Research Plan (Grant No. D20181106) for financially supporting this work.