NiめっきSKD11基材上に生成したCu微粒子による微細孔PVD硬質膜の密着性と摩擦特性

Abstract

Deposition of micropored PVD hard coatings can be achieved using Cu microparticles fabricated on Ni-plated SKD11 substrate using square-wave pulse current electrolysis method. In this new process, reducing pin-holes in the Ni layer is crucial for stable generation of Cu particles because excessive deposition of Cu occurs to offset the current of dissolution of steel substrate at pin-holes in the Ni layer. Multilayered Ni plating reduced the number of pin-holes of Ni film of the SKD11 substrate. Moreover, no change was found in adhesion of CrN coating with the substrate. Increasing the thickness of the Ni film slightly decreased the adhesion of the CrN coating; a critical load higher than 50 N was maintained with the film thickness less than 1 μm. Pin-on-disk testing of the CrN coating with micropores with applied MoS2 as lubricant showed that the micropores brought about a low friction coefficient. Cupping test results demonstrated that maximum drawing force was lower when Cu microparticles remained on the CrN films. We concluded that friction properties of the coatings by this new process were equivalent to or superior to those obtained using previously reported processes using polymer microparticles.