TEM Structure, Nanomechanical Property, and Adhesive Force of Magnetron-Sputtered Cr-DLC Coating on a Nitrided Ti₆Al₄V Alloy

Abstract

A magnetron-sputtered Cr-diamond-like carbon (DLC) coating was deposited on nitrided Ti6Al4V alloys (TAs) by employing the CrN interlayer. The physical and chemical characteristics of the obtained coating were systematically studied using scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, atomic force microscopy, X-ray diffraction, nanoindentation, and scratch tests. The results show that the Cr-DLC coating is an amorphous structure of carbon (C), and the Cr clusters are dispersed in the Cr-DLC coating. Raman analysis also confirms the existence of G and D peaks in the Cr-DLC coating. The Cr-DLC coating presents outstanding nanomechanical properties, and its nanohardness and elastic modulus are 19.29 and 168.8 GPa, respectively, which are contributed to the formation of diamond. The adhesive force of the Cr-DLC coating with the nitrided TA is determined to be 20.70 N by the scratch test, which is improved by the Cr–C bond of the CrN interlayer at a binding energy of 283.4 eV.