TIB2-COATED CATHODES FOR ALUMINUM SMELTING CELLS

Pipes consisting of coatings 700 mu m thick of chemically vapor-deposited TiB//2 on carbon were produced and tested for corrosion and/or erosion resistance in a laboratory aluminum smelting cell for 100 h. The projected lifetime of the coating was approximately 30 days, a factor of 50 shorter than that projected by assuming uniform saturation dissolution of TiB//2 in molten aluminum. The corrosion and/or erosion as measured from scanning electron micrographs pointed to grain boundary attack with subsequent crystalline pull-out as the mechanism for the shorter than expected lifetimes.