US 4,544,524 AGranted

Process for manufacturing solid cathodes

AssigneeSwiss Aluminium Ltd.

InventorsTiberiu Mizrah, Matthias Hoffmann, Peter Kaser, Klemens Heilig

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Abstract

The solid cathodes built into reduction cells for aluminum production have at least one workface which can be wet by the precipitated metal. The starting materials, which contain titanium, boron and carbon in powder form, are first intimately mixed in such proportions that the sum of the powdered carbon and any carbon extracted from the substrate is in excess with respect to the amount required by the starting materials to form titanium diboride. This mixture is heated under a neutral or reducing atmosphere to 1600.degree.-2200.degree. C. and held for 5-45 min at this temperature. The reaction product containing pores and channels is then heated further, to 2250.degree.-2600.degree. C., and held there for 10-60 min to form a compact titanium diboride/carbon eutectic. Subsequently, the solid cathode is cooled to room temperature.

Claims14

Dependent claims

A process for manufacturing solid cathodes for the fused salt electrolytic production of aluminum wherein the cathode material is wettable by precipitated aluminum comprising:

mixing a powdered titanium and a boron containing material with a powdered carbon material wherein the ratio of the sum of the powdered carbon material is super stoichiometric in an amount between 5 to 20 wt. % in excess of the required stoichiometric amount with respect to said powdered titanium and a boron containing material to form titanium diboride so as to form a mixture;
heating said mixture to a first temperature of about between 1600.degree. to 2200.degree. C.;
holding said heated mixture at said first temperature for about 5 to 45 minutes to form a reaction product characterized by pores and channels;
heating said reaction product to a second temperature of about between 2250.degree. to 2600.degree. C.;
holding said heated reaction product at said second temperature for about 10 to 60 minutes to form a molten titanium diboride-carbon eutectic;
and
forming a wettable cathode from said molten titanium diboride-carbon eutectic.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/658,521Filed 9 Oct 1984 · continuation
Priority: CH 740/8310 Feb 1983
Granted: 1 Oct 1985
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

C04B 35/58071
Based on refractory borides: based on titanium borides
C04B 35/64
Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products: burning or sintering processes
C04B 35/65
Burning or sintering processes: reaction sintering of free metal- or free silicon-containing compositions
C25C 3/08
Of aluminium: cell construction, e.g. bottoms, walls, cathodes