A technique for fabrication of coated TiCN-based cermets with functionally graded structure

摘要

A technique for fabrication of coated TiCN-Ni-Mo cermets with functionally graded microstructure and composition has been developed. A multilayer coating and the substrate near-surface zone with graded microstructure form as a result of interaction between the cermets and chromium vapour in vacuum. The coating consists of an upper layer of chromium carbide of about 10 #mu#m in thickness and a thin interlayer of less than 1 #mu#m composed of a Ni-Cr alloy between the carbide layer and the substrate. The wide near-surface zone of over 100 #mu#m in thickness with graded microstructure and composition forming under the coatings has an increased Cr content in the Ni-based binder. This zone is characterised by enhanced corrosion- and oxidation-resistance.