from the conferences organized by TANGER Ltd.
Industrial branches are developing the best materials for their applications. An important part of surface engineering is represented by Physical Vapor Deposition (PVD) and Thermal Spraying techniques. The present work aims to investigate and compare the properties of multilayer coating systems obtained from PVD deposited Diamond-like Carbon (DLC) films on top of High Velocity Oxy-Fuel thermal sprayed WC-CoCr cermet interlayers to those of as-sprayed cermet coatings. In order to determine the coatings characteristics, the morphology, microstructure and chemical composition have been analyzed by means of Scanning Electron Microscopy combined with Energy-dispersive X-ray Spectroscopy (EDX). The EDX line-scan analysis confirms the existence of a gradient coating. The adhesion layer is a mixture of carbides, nitrides and carbonitrides. The presence of the cermet interlayer has several advantages like promoting adhesion to the metallic substrate and exhibiting a gradual distribution of the metal into ceramic, offering a better opportunity for the phase distribution of the top layer. Therefore, a further used method for the characterization of the cermet coating was X-ray diffraction. Several transformations in the phase content were observed and a decomposition of the ceramic phase was detected. The coefficient of friction, measured with a Pin-on-Disc Tribometer, stabilized quickly and remained constant for the WC-CoCr coating, whereas in the case of DLC/WC-CoCr it showed a lower steady state value with light fluctuations. Polarization measurements revealed a considerable dissolution of the metallic binder in the case of WC-CoCr coatings. Meanwhile, the DLC/WC-CoCr multilayer system performed significantly better under the same electrochemical testing conditions.
Keywords: DLC, WC-CoCr, HVOF, sputtering, multilayer coatings© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.