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Porous materials are useful as lightweight structures, bone substitutes, and thermal insulators, but exhibit poor mechanical properties compared to their dense counterparts. Biological materials such as bone and bamboo are able to circumvent this trade‐off between porosity and mechanical performance by combining pores at multiple length scales. Inspired by these biological architectures, a manufacturing platform that allows for the fabrication of Al2O3 foams and Al2O3/Al composites with hierarchical porosity and enhanced mechanical properties is developed. Macroscale pores are formed through the assembly of aluminum particles around templating air bubbles in wet foams, whereas the thermal oxidation of the metal particles above 800 °C generates porosity at the micrometer scale. After elucidating the mechanism of pore formation under different sintering conditions at the microscale, the mechanical performance of the resulting hierarchical foams using compression experiments and finite element simulations is evaluated. Porous materials manufactured via this simple approach are found to reach unparalleled mechanical properties with near‐zero sintering shrinkage and minimum loss in mechanical strength. The ability to produce macroscopic objects with ultrahigh strength at porosities up to 95% makes this an attractive manufacturing technology for the fabrication of high‐performance lightweight structures or advanced thermal and acoustic insulators. [ABSTRACT FROM AUTHOR]

In situ coagulation for yttria‐stabilized zirconia (YSZ) suspension via polyvinyl pyrrolidone (PVP) crosslink is reported. PVP is used to prepare sterically stabilized YSZ suspension. Influence of PVP on the dispersion of YSZ suspension was investigated. It indicates that well disperse YSZ suspension with 0.3 wt % PVP can be prepared. Dimethyl sulfate (DMS) was added at 40 °C to coagulate the suspension after degassing. Influence of DMS content and coagulation temperature on coagulation process and properties of green bodies were investigated. It indicates that sufficiently high viscosity to coagulate the suspension is achieved with the addition of 1 vol % DMS at 60~80 °C. The coagulation mechanism is proposed that the YSZ suspension is destabilized by the self‐crosslink of PVP. Coagulated samples with the highest wet compressive strength of 6.34 MPa could be demolded without deformation by treating 50 vol % YSZ suspension at 60 °C. Dense YSZ ceramics with relative density above 99.1% and flexural strength of 920 ± 90 MPa had been prepared by this method sintered at 1450 °C for 3 h. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48889. [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]

Ultralight ceramic foam materials with high porosity play an important role in increasingly hi‐tech areas due to the combinative merit of ceramic material and highly porous structure. So far, it remains challenging to fabricate alumina ceramic foams with extremely high porosity and high specific surface area that are comparable to aerogel materials by employing a low cost, eco‐friendly and convenient approach. For the first time, we propose the preparation of aerogel‐like ceramic foams with nanoscale cell wall and unprecedentedly high porosity using boehmite sol as both ceramic source and bubble interface stabilizer, based on sol nanoparticles stabilized foams using sodium lauryl sulfate (SDS) as modifier. The obtained ultra‐stable sol foams allow for the achievement of bulk foams with ultrathin cell wall with thickness in the range of 30‐90 nm, super‐high porosity up to 99%, and large specific surface area of 280 m2/g, which is attributed to the well‐organized assembly of nanoparticles at the liquid/air interfaces. This novel foam material demonstrates excellent adsorption ability for polar volatile organic gases (VOCs) due to its extremely high porosity and large specific surface area. Ultralgiht cellular ceramic foams composed of uniformly assembled nanoparticles with nanoscale cell wall. [ABSTRACT FROM AUTHOR]