Nano-multilayer Ti–Zr–N coating by a central configured multi-arc coating process

Abstract

In this work, a novel arc ion plating (AIP) system, consisting of a centrally configured multi-arc source array (CCMA), is developed. This system is aimed to satisfy the present industrial demands for the large-scale production of multicomponent, multilayered, and superlattice coatings. The central array is made up of three flat, independently powered, arc sources. These form a triangular pillar. The newly developed CCMA AIP system is used to deposit TiN/ZrN coatings, in order to evaluate its performance. The surface hardness of the specimens is measured by micro Vickers indentation. A scratch test is used to determine the adhesive strength of the coatings. Scanning electron microscopy (SEM) is used to observe the cross-sectional morphology and to measure the film thickness. An energy dispersive spectrometer (EDS) is used to characterize film composition. The crystal structures of the coatings are characterized by an X-ray diffractometer and transmission electron microscope (TEM). The deposited coatings range from a micro- to nano-layered (TiN/ZrN) structure as the rotation speed of the substrate table was increased. Each layer exhibits a (111) preferred orientation. At rotating speeds in excess of 10 rpm, a nano-multilayered Ti(Zr)N structure is formed, again with each layer having (111) preferred orientation. At the highest rotation speeds the greatest surface hardness and film adhesion strength are attained. This is attributed to the maximized stress accommodation of the nano-multilayer structure, through the different shear elastic modulus of each layer. This research demonstrates that this novel CCMA AIP system is highly flexible in coating material design and capable of mass production.