Method for coating a porous electrode

Claim 1

Method for coating a porous sintered electrode unimpregnated with a ceramic oxide without also coating the porous interior of the electrode, for electrochemical processes with an activation layer which covers the electrode surface at least in part and contains metals and compounds of metals of the platinum group, which comprises coating the porous electrode surface to be covered by an activation layer with a suspension containing dispersed particles of a compound of a metal of the platinum group in a dispersion agent in which the particles will dissolve at an elevated temperature, the particles of the compound of a metal of the platinum group having diameters larger than the pore diameters of the electrode permitting the dispersion agent only to enter the pores, heating the coated electrode to an elevated temperature to dissolve the dispersed particles of the suspension in the dispersion agent, heating the electrode to deposit a layer of the metal of the platinum group on the electrode surface by evaporating the agent and decomposing the compound by heating the electrode to a temperature between 250° and 350° C.; repeating the cycle a plurality of times to obtain a layer of desired thickness; and then heating the electrode in an oxygen-containing atmosphere to a temperature between 400° and 600° C.