Effects of Initial Defect Morphology upon Corrosion Resistance of TiN Thin Film Coating Made by Dynamic Ion Mixing Method
Michio OHATA and Yuji KIMURA
Abstract:Ceramic coating was widely used as film coating technology, due to superior corrosion resistance, wear resistance and high hardness. However, various types of defect in nm or ƒÊm levels such as pinhole defect and crack were inevitably existed in thin film due to film formation process. Depending on these various factors, localized corrosion was generated and even developed into micro-cracks in some cases, when ceramics coating was applied in corrosive environments. And also, evaluation of corrosion resistance of ceramic thin film coating, the electrochemical potential sweep methods were employed due to superior reproducibility and simple experimental procedure. However, corrosion pit was not necessarily formed depending on the difference of corrosion resistance of coated thin film in case when the potential was swept up to relatively higher value. Therefore, the understanding of correlation between localized corrosion progress and defect morphology of thin film coating was needed. The defect morphology and nm or ƒÊm order's localized corrosion process generated on various types of defects in 3% NaCl aqueous solution was examined by Atomic Force Microscopy observation. And also, difference in localized corrosion behavior in relation to kinds of defects was investigated. As a result, the correlation between localized corrosion behavior and the kinds of defects in film that existed from the initial stage was recognized in TiN thin film. Key Words:TiN thin film coating, Localized corrosion morphology, Initial defect morphology, Atomic force microscopy, 3% NaCl aqueous solution