Formation of a Nanostructured Ti‐Si‐C‐N Coating by Self‐Organization with Reduced Amorphous Matrix

Abstract

A Ti‐Si‐C‐N coating is deposited on AISI H11 hot working steel by plasma‐enhanced chemical vapor deposition (PECVD) to investigate its micro‐ and nanostructure as well as its mechanical and thermal properties. Instead of a nanocomposite structure consisting of randomly oriented nanocrystalline (nc‐) grains < 10 nm surround by an amorphous (a‐) matrix, as usually found for these systems, this Ti‐Si‐C‐N coating shows much larger Ti(C,N)‐grains with a preferred (200) orientation identify by X‐ray diffraction analysis. The strong texturing and grain sizes > 10 nm of the coating are confirmed by high‐resolution transmission electron microscopy images. The coating's hardness is 46.3 GPa, making it equally hard to, e.g., nanocomposite Ti‐Si‐N coatings. These hardness values can only be achieved by a strong interface between a‐matrix and nc‐grains and small grain size. Despite 41.1 at.% carbon content, no significant quantity of a‐C is found, as evidenced by Raman spectroscopy analysis. In order to investigate the oxidation behavior of the coatings, X‐ray diffraction experiments are carried out at room temperature and in‐situ in ambient atmosphere at elevated temperatures. The room temperature measurement shows a strong texturing of the Ti(C,N) lattice and yielded additional information on an anisotropic grain size.