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Electrochemical Protection against Corrosion

Molybdenum electrodes are mostly used for the electric melting of glasses. They are attacked by the glass melt and worn off with time. The extent of wear is different dependent on the composition of the melt, the melting temperature, the electrical heating capacity, besides other things. In the literature, three electrochemical means of protection are known: anodic and/or cathodic protection and frequency adaptation. HVG has been active in the field of the cathodic protection of molybdenum electrodes for over ten years.

Lab tests and experiments in industrial practice proved that for soda-lime silicate glass the electrochemical cathodic electrode protection clearly reduces the wear of molybdenum electrodes. On a full-electric furnace, a decrease in the molybdenum removal by almost 50 % was achieved. This is seen in the molybdenum content of the glass product as represented in the graph to the right.

HVG has the expertise to assist in the installation and design of cathodic electrode protection on full-electric furnaces and furnaces with electric boosting. For this purpose, one has to consider glass type, combination of the heating electrodes, skew of the heating voltages, AC voltage potentials at the individual electrodes and variation fields of the glass melt temperature with the throughput. Since the capital expenditure is comparatively small, the cathodic protection is also economically reasonable for electrodes that are shifted and/or replaced repeatedly per year.