Adhesion Strength of the Interface between Tin Film and White Layer

TiN coatings on white layer composed of ɛ nitride (Fe2-3N) were studied to improve adhesion strengths. A hot work tool steel, SKD61, was used for a substrate. The substrates were coated with TiN by physical vapor deposition (PVD). Specimens were prepared with changing the conditions for polishing the surface of the substrate, and conditions for nitriding before PVD treatment. Adhesions of the TiN coating were evaluated using a Rockwell indentation tester and a scratch tester. The scratch tests showed that the adhesion strengths of the specimens with white layer were higher than those on the specimen without the white layer. The white layer which is formed in the nitriding process before PVD coating have little adverse effect on the adhesion of TiN film, although polishing the surface of the white layer improved the adhesion.