Nanoscale modification of hard coatings with ion implantation

Abstract

The mechanical properties of new hard coatings based on a multilayer structure have been investigated at the nanometre scale. The multilayer structure consists of a nitrided layer on a steel substrate and a hard coating deposited by Physical Vapor Deposition and Ion Beam Assisted Deposition. In the present investigation the subsequent ion implantation was provided by N2+ ions. This paper describes the use of the nano-indentation technique for a determination of the hardness and elastic modulus. The results are analyzed in terms of load-displacement curves, hardness, Young's modulus, unloading stiffness and elastic recovery. The analysis of the indents was performed with an Atomic Force Microscope. The analyzed AE signal was obtained by a scratch test designed for adherence evaluation. The coating is often in tensile stress with greater microhardness. The stress determination follows the conventional sin2 ψ method, using an X-ray diffractometer. A variety of analytic techniques were used for the characterization, such as a scratch test, calo test, SEM, AFM, XRD and EDAX for engineering applications. The experimental results indicated that the mechanical hardness is elevated by the penetration of nitrogen, whereas the Young's modulus is significantly elevated.