Long Term Behaviour of Ceramic Tubular Shaped Anodes for Cathodic Protection Applications, Sergi, Simpson & Hayfield

Ceramic tubular electrodes have been in use successfully as discrete anodes in impressed cathodic protection (CP) applications for several years tolerating current densities several times higher than most commercially available anodes. They owe their success to the stable highly conductive nature of the particular titanium suboxide used.  Although stable, the titanium sub-oxide ceramic is known to slowly polarise when subjected to extreme cathodic current densities so it was important to determine their longevity under such strong polarising conditions. A long term programme was, therefore, initiated in 1994 with the objective of monitoring the performance of anodes embedded in steel reinforced concrete blocks over a period of between 7 and 12 years under a range of polarising levels. The work was supplemented by subjecting tubular anodes to the NACE Standard Test Method (NACE Standard TM0294-2001) at normal and four times normal current densities by surface area of the anode at equivalent charge levels of up to 100 years at 110mA/m2 and 900mA/m2.  Electrochemical results indicated a very good performance of the anodes over the test period and showed clearly that any polarisation of the anodes was acceptably low. (read more)