Porous ceramic materials are currently used as volumetric sunlight absorbers in concentrating solar power systems. As the efficiency of thermodynamic cycles rapidly increases with the operating temperature, the favorable characteristics of so-called ultra-high temperature ceramics (UHTCs) can be successfully exploited in novel solar absorbers. The present work reports, for the first time to the...

Ice-templating techniques, including freeze-drying and freeze casting, are extremely versatile and can be used with a variety of materials systems. The process relies on the freezing of a water based solution. During freezing, ice nucleates within the solution and concentrates the solute in the regions between the growing crystals. Once the ice is removed via sublimation, the solute remains in ...

Natural and synthetic hydroxyapatite (HA) scaffolds for potential load-bearing bone implants were fabricated by two methods. The natural scaffolds were formed by heating bovine cancellous bone at 1325°C, which removed the organic and sintered the HA. The synthetic scaffolds were prepared by freeze-casting HA powders, using different solid loadings (20–35 vol.%) and cooling rates (1–10°C/min). B...

The processing of ceramic scaffolds using the ice-templating, or freeze casting, technique provides a relatively simple means to mimic the hierarchical design of natural materials such as nacre. In the present study, we investigated the architecture of silicon carbide (SiC) scaffolds produced by this technique over a range of cooling rates and suspension characteristics to demonstrate its versa...

A three-dimensional porous architecture makes an attractive electrode structure, as it has an intrinsic structural integrity and an ability to buffer stress in lithium-ion batteries caused by the large volume changes in high-capacity anode materials during cycling. Here we report the first demonstration of a SnO2-coated macroporous Cu foam anode by employing a facile and scalable combination of...

Porous graphene nanostructures are of great interest for applications in catalysis and energy storage. However, the fabrication of three-dimensional (3D) macroporous graphene nanostructures with controlled morphology, porosity and surface area still presents significant challenges. Here we introduce an ice-templated self-assembly approach for the integration of two-dimensional graphene nanoshee...

Directional freeze-casting – a process used to create foams with elongated, aligned pores applied so far exclusively for ceramics – is demonstrated for titanium foams. An aqueous slurry of <45 lm titanium powders was directionally solidified, resulting in a powder preform consisting of elongated, aligned dendrites of pure ice separated by interdendritic regions with high powder content. After f...

Graphene-based three-dimensional porous macrostructures are believed of great importance in various applications, e.g. supercapacitors, photovoltaic cells, sensors and high-efficiency sorbents. However, to precisely control the microstructures and properties of this material to meet different application requirements in industrial practice remains challenging. We herein propose a facile and hig...

This is a review article covering literature reported on consolidation of ceramic components out of aq.-based Al2O3, MgAl2O4 spinel, β-Si4Al2O2N6, β-SiAlON-SiO2 composite, and zirconia toughened alumina (ZTA) slurries following hydrolysis induced aq. gelcasting (henceforth referred to as GCHAS) route. GCHAS is a combination of aq. gelcasting (GC) and hydrolysis assisted solidification (HAS) rou...

The RheoMetal process (previously called the Rapid Sand RSFprocess) is a novel method to produce cost effective, high quality, semisolid slurries for component casting. The RheoMetal process uses an Enthalpy Exchange Material (EEM) as cooling agent to absorb heat and produce a slurry. Critical process parameters to create a slurry by robust melting of the EEM are alloy content, stirring speed, ...