| 摘要 |
A multi-layer cathode block for an electrolytic cell having at least a surface layer having a surface expansion index and a second layer having a second expansion index is disclosed, wherein the surface layer including a surface wetting agent in a first total amount; and the second layer including a wetting agent in a second total amount, wherein the surface wetting agent and the wetting agent are selected from the group comprising: a metal boride, metal boride precursors, and mixtures of the metal boride and metal boride precursors; the surface layer being directly superposed to the second layer, the wetting agent in the second layer including metal boride precursors that react together to generate a metal boride component in situ when the cathode block is exposed to start-up and operation conditions of the electrolytic cell, the second total amount being lower than the first total amount, and selected so as to minimize the difference between the expansion indexes of the surface layer and the second layer. Also disclosed is a process of producing multi-layer cathode structures having at least a surface layer with a surface expansion index and a second layer with a second expansion index, the process includes the steps of: (a) forming the second layer containing a carbonaceous material and a wetting agent in a second total amount, the wetting agent including metal boride precursors that react together to generate a metal boride component in situ when the cathode block is exposed to start-up and operation conditions of an electrolytic cell; and (b) superposing the surface layer to the second layer, the surface layer including a surface wetting agent in a first total amount, wherein the total amount of wetting agent in the second layer and the surface layer decreases progressively as the distance between the layer and the surface increases and the difference between the expansion indexes is selected to minimize surface cracking.
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