Sprayed titanium coatings for the cathodic protection of reinforced concrete

Thermally sprayed titanium coatings were investigated in the laboratory as anodes for the cathodic protection of reinforced concrete. Three proprietary catalyst systems were used to activate the titanium anode coatings. Some experiments were conducted that applied the catalyst as a precoat on the metallizing wires; in other experiments, the catalyst solution was applied onto concrete blocks before or after arc spraying with titanium. The coated reinforced concrete blocks were powered at a constant current density and in a 95% relative humidity for more than 95 days. The driving voltages measured across the samples demonstrated that precoating the catalyst on the titanium wires had little effect on the driving voltage over the recorded lifetime. In other experiments, where the catalyst was directly applied to the surface of the reinforced concrete blocks, only the cobalt oxide catalyst significantly reduced the driving voltage requirements. The cobalt oxide reduced the driving voltages regardless of whether it was applied on the concrete blocks before or after arc spraying with titanium.