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Engineering highly porous SiC foams with interconnected cellular architecture and satisfactory compressive strength for the practical applications remains a challenging task. In the current work, SiC foams bonded by in-situ formed mullite phase were fabricated via polyurethane foaming using boehmite sol-coated SiC powder as the raw material. The strategy in the current work endowed the resultant products with ultrahigh porosity, interconnected pore structure, and a robust mullite bonding phase among the SiC particles. The resulting products with this cellular architecture possessed a high porosity level of 88.5% and maintained a robust compressive strength of 2.56 MPa. Our results showed that as-prepared products are promising for practical applications in the filtration, adsorption and catalytic areas. [ABSTRACT FROM AUTHOR]

Engineering mechanically robust ZrO2 foams with three‐dimensional (3D) reticular architecture and high porosity is extremely challenging. In current work, we presented an approach for constructing such cellular ceramics via a combined polyurethane foaming and chemical grafting method. Ester functional groups were chemically grafted on the ZrO2 powder surface to enhance its dispersibility. This approach caused the micron‐sized windows to assemble onto the cell wall of porous framework, contributing to 3D interconnected reticular architecture. The resulting products with such cellular architecture possessed a high porosity level of 89.2% and maintained an ultrahigh compressive strength of 8.5 MPa. Our results open up new opportunities for fabricating high‐performance ZrO2 foams toward practical applications. [ABSTRACT FROM AUTHOR]

Engineering high performance cellular ceramics with both ultralow density and satisfactory compressive strength for practical applications still represents a grand challenge. Herein, alumina-based cellular ceramics bonded by in-situ formed mullite phase were constructed by Al 2 O 3 –Si-boehmite particle-stabilized foams. The gelation of boehmite sol improved the stability and harnessed the deformation of dried Al 2 O 3 –Si composite foam. The oxidation of silicon and further generation of in-situ mullite phase enhanced the chemical bond between alumina particles on cell walls, resulting in the superior mechanical properties. As an exemplar, the resulting cellular ceramic possessed the robust compressive strength of 2.26 MPa at a high porosity of 87.8%. The gelation-assisted Al 2 O 3 –Si particle-stabilized foams provide a facile and convenient strategy for construction of composite ceramic foams with high porosity and robust strength. [ABSTRACT FROM AUTHOR]

Hierarchical cellular architectures hold great potential in a vast range of applications due to their superior mechanical properties and multifunctionality. In the present work, hierarchical structures composed of porous struts patterned in the form of quadrangular and triangular honeycombs were fabricated via direct foam writing (DFW) using colloidal particle‐stabilized Al2O3‐MgO‐SiO2 foams as the ink. Hydration process of MgO and subsequent formation of colloidal Mg(OH)2 network endowed the foam ink with viscoelasticity and high storage modulus. The resulting honeycombs with ultrahigh overall porosity (95.3%) and robust compressive strength (2.5 MPa) can be readily fabricated by DFW. The current work exhibits a significant step toward the scalable production of cellular ceramics with hierarchical architecture for various applications, including tissue scaffolds, catalyst supports, thermal insulation, and lightweight structures. [ABSTRACT FROM AUTHOR]

Ultralight ceramics with striking mechanical properties and improved pore connectivity could have wide applications in areas ranging from catalyst support to hot gas filtration. However, creating such materials has proven to be a challenging target. This work demonstrated a novel methodology to prepare porous MgAl 2 O 4 ceramics by calcining gelled MgO–Al 2 O 3 –SiO 2 particle-stabilized foams. The striking green strength of dried foams can be achieved as a consequence of MgO hydration and subsequent formation of gelled Mg(OH) 2 and MgO–SiO 2 –H 2 O skeleton. The decomposition of colloidal substance at elevated temperature resulted in the formation of small pores on the cell wall, thus forming the hierarchical porous architecture and improving the pore connectivity. The highly porous MgAl 2 O 4 ceramics fired at 1600°C possessed the integrated properties of ultrahigh porosity (87.0%), improved pore connectivity and satisfactory compressive strength (7.93 MPa), showing great potential to be used in multiple industrial fields. [ABSTRACT FROM AUTHOR]

Ceramic foams with significant porosity and robust mechanical properties have received extensive attentions. However, it is still difficult to achieve excellent compressive strength at high porosity levels. In this work, a gelation of foamed boehmite sol method is proposed to settle this issue. The technological parameters during preparation process are systematically investigated. As‐prepared alumina ceramic foams possess unprecedentedly high compressive strength of 34.1‐89.1 MPa at high porosity levels of 66.0%‐87.2%, which is attributed to the present of hierarchical pore structure, small grain size and pore size. This work demonstrates a facile and novel method for the fabrication of high‐performance alumina ceramic foams toward practical applications. [ABSTRACT FROM AUTHOR]

Compressive strength is one of the most important mechanical properties for ceramic foams but the dependence of compressive strength of highly porous ceramic foams on porosity remains unclear up to now, especially for the ceramic foams with porosity above 94%. In this paper, the relationship between compressive strength and porosity of ceramic foams with high porosity in the range of 79–98% was studied for the first time. The alumina ceramic foams and zirconia foams were prepared by particle-stabilized foaming method using sodium dodecyl sulfonate (SDS) as foaming agent. It was found that the function relation between compressive strength and porosity depended on porosity level. Specifically, compressive strength of ceramic foams fitted well with Rice Model when the porosity ranged from 79% to 94%. When the porosity increased above 95%, compressive strength of ceramic foams showed linear relation to porosity, which was probably due to the characteristic of highly porous ceramic foams with thin and lamellate cell wall. [ABSTRACT FROM AUTHOR]