Electrodes of improved service life

An electrode metal substrate providing an electrode of enhanced service life with low electrode coating weights, which metal substrate has:

• (A) a roughened surface having a profilometer-measured average surface roughness of at least about 250 microinches and an average surface peaks per inch of at least about 40, said roughened surface being provided by one or more of the following means:
• (a) intergranular etching of said substrate metal, which etching provides three-dimensional grains with deep grain boundaries;
• or
• (b) melt spray application of a valve metal layer onto said metal substrate;
• or
• (c) melt spraying of ceramic oxide particles onto said metal substrate;
• or
• (d) grit blasting of the metal substrate surface with sharp grit to provide a three-dimensional surface;
• there being with said roughened surface;
• (B) a ceramic oxide barrier layer with, said barrier layer being established in means (c) where there is subsequently established after any of means (a), (b), and (d), said ceramic oxide barrier layer on said roughened surface, which barrier layer is provided by one or more of:
• (1) heating said roughened surface in an oxygen atmosphere to an elevated temperature in excess of about 450.degree. C. for a time of at least about 15 minutes;
• or
• (2) applying a metal oxide precursor substituent, with or without doping agent, to said roughened surface, said metal oxide precursor substituent providing a metal oxide on heating, followed by thermally treating said substituent at an elevated temperature sufficient to convert metal oxide precursor substituent to metal oxide;
• or
• (3) establishing on said roughened surface a suboxide layer by chemical vapor deposition of a volatile starting material, with or without doping compounds, which is transported via an inert gas carrier to the surface that is heated to a temperature of at least about 250.degree. C.;
• or
• (4) melt spraying ceramic oxide particles onto said roughened surface;
• with there being maintained for said barrier-layer-containing surface a profilometer-measured average surface roughness of at least about 250 microinches and an average surface peaks per inch of at least about 40.