Preparation and some properties of porous alumina ceramics obtained by the gelatination of ammonium alginate

Defect and microstructural evolution during drying of soapnut-based alumina foams

“…In direct foaming process, major microstructural changes occur during consolidation of foamed slurry either by drying, gelling or freezing. [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] Foams processed by direct foaming of slurries have a tendency to develop defects such as cracks, delamination, warpage during drying. The capillary stress rise due to evaporation of water from the surface plays a role in formation of cracks.…”

Processing of cellular ceramics by foaming and in situ polymerisation of organic monomers

“…The routes and substances currently used for the setting of fluid suspensions, regardless of whether they have been previously foamed, can be classified as follows: drying or freeze-drying of the solvent [10], compositions which can form a gel intrinsically [11], the incorporation of gelling substances such as cellulose derivatives [12] or alginates [13], and the in situ polymerisation of monomers [14][15][16][17][18].…”

Tailoring Porosity and Pore Characteristics in Oxide Ceramic Foams through Controlled Processing

“…1). [14][15][16][17][18][19][20][21][22][23][24] These organic materials burnt away leaving behind porosity, have been referred to as fugitives. The porosity developed in the ceramic compacts has almost close pores with identical features in terms of the pore size, geometry as that of the fugitives used.…”

“…A method for producing porous alumina compacts from gelatination of ammonium alginate by the ion-exchange reaction of NH 4 + and H + ions was demonstrated by Kastuki et al 24 In this process a mixture of alumina particles (0.4 µm), alginate polymer and deflocculant (ammonium polycarboxylate) was dropped into 0.1 to 2 N HCl solution at 24 o C from a burette nozzle to promote the ion-exchange reaction of NH 4 + and H + ions. Due to this ion-exchange reaction ammonium alginate formed a film (gel like material) which enveloped the alumina particles.…”