Structure and tribological properties of DLC:Si/AlCrN low friction thin film

Abstract

A wide range of diamond-like carbon coatings is caused by their structure composed of sp2 and sp3 carbon hybridisation and the possibility of both metallic and non-metallic admixtures or the creation of a hydrogenated form. One of the ways to improve the tribological properties of DLC is to dope it with silicon. Deposited on stainless steel substrate coating system composed of AlCrN film covered by DLC:Si was the subject of the studies. The AlCrN and DLC:Si layers were deposited by PVD lateral rotating ARC-cathodes and PACVD on the X6CrNiMoTi17-12-2 steel respectively. Characteristics of DLC:Si film was performed by imaging the topography using SEM and AFM. The structure was investigated using a Raman spectroscopy and HRTEM. Tribological and adhesion tests were carried out using a ball-on-disc and a scratch test respectively. Tests using the TEM confirmed an amorphous character of DLC:Si layer. A phase composition analysis of the DLC:Si layer with the Raman spectroscopy method showed the presence of bonds distinctive for diamond (sp3) and graphite (sp2), typically observed in DLC coatings. Under the technically dry friction conditions, the friction coefficient for the associations tested is within the range 0.14 for the investigated coating.