Abstract: The invention involves a method of making a holder of solid ceramic material by locating a core in a mass of particulate ceramic material, consolidating the particulate material around the core, removing the core from the particulate material to leave a green artifact having a cavity, and sintering the green artifact. The core is shaped and the particulate material is arranged such that the core is in the form of a thin slab between a pair of layers of the particulate material. After sintering, the cavity comprises a thin gap between opposed plates of sintered ceramic material. The slab has openings therethrough which are filled with the particulate material, which, after sintering, forms a bridge across the gap, between the associated plates and sintered thereto.

Abstract: The invention provides a solid electrolyte separator for separating two electrodes from each other in an electrochemical cell. The separator is of composite layered construction and comprises at least one porous layer of solid electrolyte material having a plurality of interconnected channels or pores in its interior and opening out of its surface, and a dense layer of non-porous solid electrolyte material. The layers are integrally bonded together, face-to-face, and each porous layer is an outer layer of the separator.

Abstract: The invention provides a method of making a flattened solid electrolyte, e.g. .beta.-alumina, envelope for use as an electrode holder in an electrochemical cell. A mouldable mixture of the .beta.-alumina with a binder is formed into sheet material and two panels of the sheet material are joined together along their peripheral edges to form the envelope. Spacing and reinforcing means is provided between the panels to space them apart and to reinforce the envelope. The edges of the panels are joined together using pressure, heat and/or solvent, after which are envelope is heated to cure the binder, volatilize the cured binder and sinter the solid electrolyte.

Abstract: The invention is concerned with preparation of dense ceramics, in particular silicon carbide.Silicon carbide is a useful structural material but difficulties of densifying by sintering have in the past created problems in the production of silicon carbide components. It is however known to use boron and carbon as additives to assist densification by sintering. In this invention a further improvement in densification is effected by carrying out such sintering in a carbon-containing reducing atmosphere such as a methane containing atmosphere. Surface silica which inhibits densification is thereby removed but without removing fine carbon.