Abstract: Describes a liquid-permeable diaphragm assembly for use in electrolytic cells, e.g., chlor-alkali electrolytic cells. The diaphragm assembly includes a foraminous cathode, a liquid permeable base mat comprising synthetic polymeric material that is at least partially resistant to the environment within the electrolytic cell on the foraminous cathode, and a topcoat of water-insoluble particulate material on the base mat. The topcoat is deposited on the base mat from an aqueous slurry comprising (i) at least one oxide, boride, carbide, nitride or silicate of a valve metal, (ii) clay mineral, (iii) hydrous metal oxide chosen from the hydrous oxides of magnesium, the hydrous oxides of zirconium, and mixtures of such hydrous metal oxides, and (iv) alkali metal polyphosphate.

Abstract: Describes a method for lowering the flow of liquid anolyte through perforations in the diaphragm of a diaphragm electrolytic cell, e.g., a chlor-alkali diaphragm electrolytic cell, comprising introducing ceramic fiber into the anolyte compartment of the electrolytic cell, e.g., during cell operation. The benefits described for lowering the flow of anolyte liquor through the diaphragm of a chlor-alkali diaphragm electrolytic cell are increasing the concentration of alkali metal hydroxide, e.g., sodium hydroxide, and decreasing the concentration of hypochlorite ion, e.g., sodium hypochlorite, in the catholyte liquor. Also describes introducing dopant material and/or fibers comprising halogen-containing polymer, e.g., fluorocarbon polymer fibers, into the anolyte compartment of the electrolytic cell in conjunction with the addition of ceramic fiber into the anolyte compartment, e.g., during cell operation.

Abstract: Describes a cathode assembly for electrolytic cells, e.g., chlor-alkali electrolytic cells, comprising a foraminous cathode substrate, a deposited erodible mat comprising synthetic (man-made) fibers, e.g., polyamide (nylon) fibers, on the foraminous surface of said cathode substrate, and a synthetic diaphragm on said erodible mat. Also described is a method for preparing the cathode assembly that comprises depositing a mat of erodible synthetic fibers on the active surface of the foraminous cathode, e.g., by drawing an aqueous slurry of the erodible synthetic fibers through the foraminous cathode, and subsequently forming, e.g., by vacuum deposition, a synthetic diaphragm on the erodible mat.