| 摘要 |
1. Cathode comprising a substrate made of titanium, nickel, tantalum, zirconium or niobium or mixtures thereof, an interlayer of a mixed oxide based on titanium and on ruthenium, and an external layer of metal oxides comprising titanium, zirconium and ruthenium. 2. Cathode according to Claim 1, characterized in that the substrate is made of nickel or titanium or of nickel or titanium alloys. 3. Cathode according to Claim 2, characterized in that the substrate is made of titanium. 4. Cathode according to one of Claims 1 to 3, characterized in that the interlayer is a mixed oxide of titanium and of ruthenium. 5. Cathode according to one of Claims 1 to 4, characterized in that the external layer of metal oxides contains titanium, zirconium and ruthenium. 6. Cathode according to Claim 5, characterized in that the external layer essentially consists of ZrTiO4 accompanied by RuO2 and optionally by ZrO2 and/or TiO2. 7. Cathode according to one of Claims 1 to 6, characterized in that the ruthenium/titanium molar ratio in the interlayer lies between 0.4 and 2.4. 8. Cathode according to one of Claims 1 to 7, characterized in that the zirconium/titanium molar ratio in the external layer lies between 0.25 and 9. 9. Cathode according to Claim 8, characterized in that the zirconium/titanium molar ratio lies between 0.5 and 2. 10. Cathode according to one of Claims 1 to 9, characterized in that the ruthenium in the external layer represents between 0.1 and 10 mol% with respect to the metals in the composition of this layer. 11. Cathode according to Claim 10, characterized in that the ruthenium in the external layer represents between 0.1 and 5 mol%. 12. Process for obtaining a cathode according to one of Claims 1 to 11, comprising the following steps: a) pretreatment of the substrate, b) coating of the pretreated substrate, using a solution A containing essentially titanium and ruthenium, followed by drying and then calcining, c) coating of the substrate obtained in (b), using a solution B comprising titanium, zirconium and ruthenium, followed by druing and calcining. 13. Process according to Claim 12, characterized in that the drying of step (b) and/or (c) is (are) carried out in air and/or in an oven at a temperature below 150 degree C. 14. Process according to Claim 12 or 13. characterized in that the calcining of step (b) and/or (c) is (are) carried out in air at a temperature of between 300 and 600 degree C. 15. Process according to Claim 14, characterized in that the calcining temperature is between 450 and 550 degree C. 16. Process according to one of Claims 12 to 15, characterized in that the substrate is subjected several times to step (b) before being subjected to step (c). 17. Process according to one of Claims 12 to 16, characterized in that the substrate is subjected several times to step (c). 18. Process for manufacturing an alkali metal chlorate by electrolysing the corresponding chloride using a cathode according to one of Claims 1 to 11. |
