Preliminary Investigation of Ceramic-Coated Anodes for Cathodic Protection.
CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL
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A cathodic protection anode was manufactured by plasma-spraying an electrically conducting lithium ferrite coating on button-shaped 99 percent pure titanium and niobium substrate. Lithium ferrite was selected because of its unique adherence to titanium and niobium substrates, as well as its good electrical conductivity, low dissolution rate, and long-range stability. The pitting behavior of the titanium substrate in chloride solutions was characterized the worst case of pitting potential was 9.66 V. The dissolution rate of the lithium-ferrite-coated anode was measured over a 2-month period and was determined to be 1 to 2 g per ampere year in an aerated 3.5 percent sodium chloride solution. No damaging effects from the tests were observed on the coating. The button-shaped anode was designed so it could be installed easily on underground pipes or on structures in water, such as waterway lock gates and elevated water storage tanks, without dewatering the structure. The ceramic coatings low dissolution rate provides the advantage that the anode can be relatively small and still provide considerable protection from corrosion. A small anode can be installed and replaced relatively easily and is less vulnerable to damage. Author
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