Stabilizers for titanium diboride-containing cathode structures
A method is described for making aluminum reduction cell components, e.g. cathodes having stabilized surfaces, which comprises mixing together a carbonaceous material, TiB 2 and up to 25% by weight of a finely divided additive consisting of a combination of two intimately mixed compounds and forming the mixture into a cell component, wherein at least a first of the two compounds has a higher melting temperature than the baking temperature. When the cell component is contacted with molten aluminum, the aluminum reacts with the additive to form a dense phase at the surface of the cell component, having low solubility in aluminum.
1. A method of making an aluminum reduction cell component having a stabilized surface that is wettable by molten aluminum, which comprises mixing together a carbonaceous material, TiB 2 and up to 25% by weight of an additive consisting of an intimate mixture of TiO 2 and B 2 O 3 and baking the mixture into a cell component having a baked surface provided with pores, wherein said TiB 2 is used in an amount sufficient to make the baked surface wettable by molten aluminium, and wherein at least one of said TiO 2 and B 2 O 3 has a higher melting temperature than the baking temperature, whereby when the cell component is contacted with molten aluminum, the aluminium wets the baked surface, penetrates the pores therein, and reacts with the additive to form a dense phase having low solubility in aluminium that seals the pores.
2. A method according to claim 1 wherein up to 10% by weight of the additive is mixed with the carbonaceous material and TiB 2 .
3. A method according to claim 2 wherein the carbonaceous material and TiB 2 are mixed in the ratio of 50% by weight of carbonaceous material and 40 to 49% of TiB 2 .
4. A method according to claim 1 wherein the TiO 2 and B 2 O 3 are mixed in a ratio of 40-50% by weight TiO 2 and 50-60% by weight B 2 O 3 .
5. A method according to claim 1 wherein the TiO 2 , and B 2 O 3 comprise particles less than 200 μm in size.
6. A method according to claim 5 wherein the particles are less than 30 μm in size.
7. A method according to claim 1 , wherein 40% by weight or more of said TiB 2 is mixed with the carbonaceous material.