COATING WITH RU AND VALVE METAL OXIDES

摘要

A method to produce an electrode by coating at least a portion of a valve metal substrate sequentially with first and second liquid solutions containing different proportions of dissolved ruthenium and valve metal values; the second solution having a greater valve metal to ruthenium weight ratio than the first solution. At least a portion of the substrate is contacted with a first liquid solution containing from about 0.25 to about 50 milligrams per milliliter ruthenium, and the valve metal in an amount of from about 0.06 to about 50 milligrams per milliliter, of the solution. The weight ratio of the valve metal to ruthenium in the first solution is from about 1:4 to about 2:1. The so-contacted surface is heated to oxidize the deposited ruthenium and valve metal values. Thereafter at least the oxidized surface is contacted with a second solution containing dissolved valve metal and ruthenium values in a weight ratio of from about 20:1 to about 2:1 and heated to oxidize the deposited metal values.