Assessing the quality of corrosion protection coatings on aluminium—Part 3 Available to Purchase

Considering the equivalent circuit in Fig 1 (see November issue) it should be noted that the magnitude of Co and Ro is hardly affected by the sealing process, the progressive filling up of pores manifesting itself in C1·1 and C1·2 changes. These tend to decrease rapidly as the sealing process progresses, whilst the dielectric losses, represented by R1·1 and R1·2, slowly increase. The barrier layer capacitance and resistance, C2·0 R2·0, on the other hand, are hardly affected by the sealing process (see Fig. 13).