Alcan International Limited

North West Water Group Plc

Michael P Thomas

Alexander P Davidson

Ernest P Butler

Steven W Summers

Rowena R Landham

Peter John Williams

David R Cowieson

A composite membrane comprises an inorganic support having interstices and porous inorganic films of sintered non-metallic particles carried by the support and bridging the interstices thereof. The support is preferably a woven metal mesh, with the films substantially coplanar with the support. The films may be formed by applying a suspension of refractory particles in a polymer solution to bridge the interstices of the support, and heating the films to partly sinter the particles. Since the films are in compression at ambient temperature, any cracks that may be formed by damage to the composite membrane tend not to propagate.

Composite membranes

A composite membrane comprises an inorganic support having interstices and porous inorganic films of sintered non-metallic particles carried by the support and bridging the interstices thereof. The support is preferably a woven metal mesh, with the films substantially coplanar with the support. The films may be formed by applying a suspenion of refractory particles in a polymer solution to bridge the interstices of the support, and heating the films to partly sinter the particles. Since the films are in compression at ambient temperature, any cracks that may be formed by damage to the composite membrane tend not to propagate.

A composite sheet comprises a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, where the membrane may be an anodic aluminium oxide membrane having an average pore diameter of 5 to 100 nm, and the microporous film is of substantially uniform pore size and substantially free of cracks and pinholes. The film may be formed by applying a colloidal sol of an aluminium alkoxide, or a solution of a polymeric precursor of a titanium oxide, to a surface of the membrane to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film.

Composite membrane

A composite sheet comprises a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, where the membrane may be an anodic aluminum oxide membrane having an average pore diameter of 5 to 100 nm, and the microporous film is of substantially uniform pore size and substantially free of cracks and pinholes. The film may be formed by applying a colloidal sol of an aluminum alkoxide, or a solution of a polymeric precursor of a titanium oxide, to a surface of the membrane to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film.

A composite membrane comprises a porous metal support and at least one porous inorganic film of sintered non-metallic particles carried by the support and overlying a surface thereof. The film is in longitudinal compression at ambient temperature, such that any cracks tend not to propagate. The composite membranes are mechanically robust and chemically inert and useful as filters e.g. in the food industry. They may be made by applying a sol or suspension of particles to form a layer on the porous metal support and heating the coated support to partly sinter the particles of the layer.

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Banbury, United Kingdom

Michael P Thomas