Electrochemical Evaluation of Pinhole in CVD, PVD Ceramic Coating

Abstract

Pinhole of CVD, PVD ceramic film coated on stainless steel was evaluated, using electrochemical measurement in various electrolytes. Cosequently, ratio of active dissolution current of a coated and a non-coated specimen in 1N HCl+0.01M KSCN solution gave the most reliable evaluation of pinhole. Results obtained are summarized as follows: (1) The pinhole ratios evaluated by this method are reproducible accurately as the substrate exposed to the electrolyte through penetrated pinholes is activated in 1N HCl+0.01M KSCN solution immediately after immersion. (2) Fewer pinholes can be evaluated compared with pre-studied methods as the anodic current by ceramic film is small and active dissolution current at pinhole is larger than ordinary electrolytes.