INVESTIGATION OF BLISTER FORMED ON COATED MILD STEEL USING SCANNING KELVIN PROBE

The degradation of a coated metal in terms of the area underneath a blister has been studied after being immersed in 3% sodium chlorida and 3% ammonium chloride solution. scanning kelvin probe (skp) was used to map electrochemical potentials, identifying anodic and cathodic regions underneath a blister and the surrounding coating. for blisters formed on coated panel immersed in sodium chlorida solution, skp potential map reveals that the blister has formed at a cathode due to alkali but anodes form nearby (not remote). meanwhile skp potential map for blister formed on coated panel in 3% ammonium chloride reveals the presence of cathodic regions within the anodic areas.