A Simple Direct Casting Route to Ceramic Foams

Abstract

A simple direct foaming and casting process using ovalbumin‐based aqueous slurries for fabricating ceramic and metal foams is demonstrated. Foaming of aqueous ceramic slurries and the foam microstructure were seen to be a strong function of slurry rheology. Setting of foams with ceramic solids loading above 20 vol% was achieved by addition of acid, which also prevented binder migration. Acid addition resulted in excessive shrinkage, causing cracking of foams with ceramic loading below 20 vol%. Addition of sucrose to the slurries suppressed shrinkage leading to defect‐free foams with porosity exceeding 95%. Overall porosity and foam microstructure could be controlled through ceramic solids loading, ovalbumin–water ratio, foaming time and sucrose amount, and sintering temperature. The ceramic foams fabricated by the process were strong enough to be green machined to different shapes.

Experience on a Low Cost Way to Obtainal-Ti Ceramic Foams

“…A denser packing of ceramics particles around these areas helps to increase the effective load bearing area hence increasing the strength 20 . The structure of the ceramic foam produced by this process of infiltration is limited by the structure of the polyurethane foam, and the process results in foams with poor mechanical properties due to the hollow struts 15 . In any case sufficient mechanical strength allows to fulfill all the requirements on application.…”

“…By this formulation, which allows percentage changes about ±5% of each major component, ceramic foams made of mullite (Al 6 Si 2 O 13 ) and others compounds like aluminium titanate (Al 2 TiO 5 ) and glass-based binding phases related to SiO 2 (phylosilicates) as starting materials 14 can be obtained ( Figure 1). It is important to remark the presence of wheat gluten below 1% in the slurry, acting as binder, that some authors replace it with ovalbumin, sucrose or other polysaccharides 15 . The aqueous ceramic slurries were prepared by roll milling the components in the presence of spherical zirconia balls during 4 hours.…”

Centrifugal Infiltration of Porous Ceramic Preforms by the Liquid Al Alloy – Theoretical Background and Experimental Verification

“…The most important are porosity (including the volume fraction of open and closed pores) as well as size distribution and morphology of pores. On the other hand, all the microstructural features depend closely on the selected route of manufacturing porous materials [8][9][10][11][12][13].…”

“…Generally, the macroporous ceramic foams (i.e. SiC, Al 2 O 3 ) with porosity in the range from 20% to 97% are produced usually by means of sintering granular materials with expanding agent [10], replication of polymer sponge [11], different direct foaming methods [12] and gel casting of foams [13].…”

Short Review: Ceramic Foam Fabrication Techniques for Wastewater Treatment Application

“…It can be produced from a broad range of ceramic materials, specifically both oxide and non-oxide, which includes metallic oxides, silicates, carbides, and aluminosilicates that are being considered for the diverse area of potential applications [3][4]. The application compatible with ceramic properties, such as low density, low thermal conductivity, stable towards high temperature, and high resistance to chemical attack [5][6].…”