Abstract: An improved alumina reduction cell is described in which the carbonaceous cathode includes refractory hard metal tiles forming the surface in contact with molten aluminum formed in the cell and intermediate tiles separating the refractory hard metal tiles from the carbonaceous cathode to prevent reaction between refractory hard metal tiles and the carbonaceous cathode in the presence of the molten aluminum.

Abstract: This invention concerns cathodes for alumina reduction cells, particularly drained cathodes, which present a refractory surface for contacting molten aluminum on the cell floor. This invention also concerns materials for constructing such cathodes.The cathodes described comprise a carbonaceous bed, preferably a graphite bed, and a composite tile. This tile is characterized by a layer of a refractory hard metal (RHM) material bonded to a base layer of a graphitic material, where the RHM layer comprises a hot pressed mixture of titanium diboride and aluminum nitride powders. The tile is further characterized by the bond between the RHM layer and the graphitic base layer, such bond having been produced simultaneously as the RHM layer is formed by hot pressing the mixture of titanium diboride and aluminum nitride powders directly against the graphitic base layer.

Abstract: The disclosure pertains to alumina reduction cells which employ refractory materials to provide a molten-aluminum contacting surface for the cathode. Specifically, configurations and methods are described according to which refractory hard metal tiles are secured to a carbonaceous substrate to produce composites suitable for constructing a molten-aluminum contacting surface for the use stated. The tiles are wettable by molten aluminum and are inert chemically to the reduction cell electrolyte. Configurations for coupling and interlocking such tiles are also described. When the tiles are coupled or interlocked in the manner taught, it is possible to achieve a built-up refractory surface which remains chemically and mechanically stable in a reduction cell environment.