Electrolytic Al production with reaction sintered multiphase ceramic

Claim 1

A component of an electrolytic aluminum production cell which in use is normally in contact with molten aluminum or in electrical contact with another component which is normally in contact with molten aluminum, characterized in that said component has a portion made of a reaction sintered ceramic consisting essentially of a fine-grained, homogeneous, intimate interdispersion of: (a) 5-95 mole percent of nitride phase or phases having a maximum grain size not greater than about 10 μm and being nitride of one or both of Al and Si, and (b) 5-95 mole percent of second phase or phases having a maximum grain size not greater than about 10 μm and being boride, carbide, silicide, sulfide or combination thereof of one or more of the elements of Groups 4b, 5 b and 6b; said reaction sintered ceramic contains 0 to 4 weight precent oxygen and is prepared by the process comprising: (c) admixing particulate reactants of maximum particle size not greater than about 150 μm and being elements, compounds, intermetallic compounds, alloys or combination thereof in stoichiometric proportions to form the nitride and second phases, and (d) shaping and heating the admixture to form the reaction sintered ceramic, the heating being done in nonreactive atmosphere and at temperature at which the reaction and sintering occurs between the reactants to substantially form the nitride and second phases.