THE EFFECT OF AlN/Ti INTERLAYERS ON THE MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF DLC COATINGS

摘要

The present study aims to demonstrate the feasibility of embedding a piezoelectric film sensor underneath a hydrogenated diamond like carbon coating (a:C-H/Cr), in order to provide the coating status life and a sufficient warning before the part failure occurs. The wear monitoring sensor composed by a bottom electrode of Ti and a piezoelectric AlN layer, along with the adhesion Cr interlayer were deposited by sputtering process, while plasma assisted chemical vapor deposition was used to build up the tribologically effective carbon coating on top of it. The effect of four types of AlN/Ti interlayers deposited under different conditions was established by determining the tribological (friction coefficient and wear behavior) and mechanical (hardness, Young's modulus and adherence) properties of the a:C-H/Cr/AlN/Ti multilayered systems. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) characterization techniques were carried out in order to evaluate the coatings and wear surfaces. The results confirmed that the AlN/Ti under-layers enhance the mechanical and tribological properties of the DLC multilayered systems compared to a:C-H/Cr coating. A high load carrying capacity and adhesion of the a:C-H/Cr/AlN/Ti composite coating was achieved by a suitable selection of the AlN/Ti support interlayers in terms of mechanical properties and thickness.