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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]

Abstract In the present work, Al 2 O 3 -Si 3 N 4 porous ceramics with a cactus-like architecture were fabricated by calcining Al 2 O 3 -Si binary particle-stabilized foams in the nitrogen atmosphere. A large number of acicular Si 3 N 4 nanobelts were constructed on the surface of cell walls as a consequence of CVD process to achieve an interlaced network. Such structure was beneficial to realize a high capture efficiency of particulate matters (PM) during filtration. Resultant products having a bulk density of 0.38 g/cm3 at an apparent porosity of 86% can potentially be applied as the air filters in environment field. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Aqueous ceramic particle-stabilized foams with UV light response are prepared. • Photocurable particle-stabilized emulsions with controllable structure are achieved. • The colloid foams/emulsions demonstrate excellent stability and photocuring ability. • Rapid and scalable synthesis of ceramic capsules is developed based on the emulsions. Abstract We herein report the design and preparation of ceramic particle-stabilized emulsions/foams with distinct ultraviolet light (UV) response, which can be used for the rapid fabrication of ceramic foams with complex shape, for synthesis of ceramic hollow spheres, and can potentially be used for 3D printing lightweight and hierarchical ceramics with porous skeleton. Photocurable foams/emulsions stabilized by ceramic particles are achieved for the first time using photosensitive oligomer as oil phase and/or using photosensitive aqueous solution containing acrylamide monomer as water phase. Four kinds of photocurable emulsions are demonstrated by adjusting emulsion structure and photosensitive phase. We further synthesize internal multiple-pore structured capsules and lightweight nanoparticle-assembled capsules in micron-scale based on the photocurable particle-stabilized, by separating emulsion into small droplets via diluting and stirring, followed by rapid curing under UV. This new strategy may potentially open opportunities for the rapid and cost-effective synthesis of high-output ceramic capsule materials. The synthesized thin-shell alumina capsules exhibit large specific area surface of 323.18 m2/g as well as uniform mesoporous structure in shell with average pore diameter of 3.4 nm, which has potential application in the fields of adsorption, load and release of materials and thermal insulation. [ABSTRACT FROM AUTHOR]

In order to reduce thermal conductivity but to exhibit better mechanical properties of porous alumina ceramics (PACs), a novel approach, based on the modification of pore structures (i.e. mean pore size, micro-pore proportions and pore shape factor) by impregnation of alumina sol, is reported in the present work. The properties of as-impregnated samples were compared with commercial alumina hollowsphere bricks. Results show that impregnation of alumina sol in PACs has a positive influence on pore structures, leading to a superior strength and a lower thermal conductivity. In particular, when 8 wt% alumina sol solid content is impregnated, the crushing strength (35.3 MPa) and thermal conductivity (0.15 W/m K at 200 °C) of sample are much better than that of the commercial alumina hollowsphere bricks. This novel method for excellent PACs provides promising applications as insulating lining materials in the fields of industrial furnace. [ABSTRACT FROM AUTHOR]