A Comparative Study in the Tribological Behavior of DLC Coatings Deposited by HiPIMS Technology with Positive Pulses

Abstract

During the last few decades, diamond-like carbon (DLC) coatings were widely used for tribological applications, being an effective tool for improving the performance and the useful life of different machining tools. Despite its excellent properties, among which stand out a high hardness, a very low friction coefficient, and even an excellent wear resistance, one of the main drawbacks which limits its corresponding industrial applicability is the resultant adhesion in comparison with other commercially available deposition techniques. In this work, it is reported the tribological results of a scratch test, wear resistance, and nanoindentation of ta-C and WC:C DLC coatings deposited by means of a novel high-power impulse magnetron sputtering (HiPIMS) technology with “positive pulses”. The coatings were deposited on 1.2379 tool steel which is of a high interest due to its great and wide industrial applicability. Finally, experimental results showed a considerable improvement in the tribological properties such as wear resistance and adhesion of both types of DLC coatings. In addition, it was also observed that the role of doping with W enables a significant enhancement on the adhesion for extremely high critical loads in the scratch tests.

Comparative Study of Tribomechanical Properties of HiPIMS with Positive Pulses DLC Coatings on Different Tools Steels

“…In the case of the vanadis 4 layers, a specific hardness of 26 GPa was obtained for the ta-C coated layer, whereas a hardness of 14GPa was reached for the WC:C layer. The results of nanoindentation are similar to those reported by García et al [34], showing values of 17 GPa for the WC:C coating and 30 GPa for ta-C. Duminica et al [27] and Czyzniewski [54] also presented similar hardness values-between 21 and 23 GPa and 19 GPa, respectively.…”

“…The use of the novel HiPIMS technique has been reported elsewhere [23,33,34]. In the first study [23], the effect of different positive voltage amplitudes on the discharge process and the mechanical properties of the deposited DLC hard coatings were studied, but no information about the resulting adherence is reported.…”

“…In the first study [23], the effect of different positive voltage amplitudes on the discharge process and the mechanical properties of the deposited DLC hard coatings were studied, but no information about the resulting adherence is reported. The works [33,34] achieved an increase in the resultant adhesion and in the wear resistance of two different types of DLC coatings, such as tetrahedral amorphous carbon (ta-C) and tungsten carbide:carbon (WC:C), using the novel high-power impulse magnetron sputtering (HiPIMS) method that incorporates positive voltage pulses after the conventional HiPIMS discharge, and that were deposited on high speed steel substrates and 1.2379 tool steel, respectively.…”

“…These conditions are more similar to the real cases of application of these coatings, such as cold stamping or forming applications, where high pressures are applied. Other studies have used similar parameters with this type of coatings [34]. The corresponding wear tracks have been measured by using a Confocal S mart Microscope (Sensofar) and an optical microscope.…”

The Influence of Plasma-Assisted Production and Milling Processes of DLC Flakes on Their Size, Composition and Chemical Structure

“…This, however, does not change the fact that this area is still valid and numerous researchers continue their studies on other forms of carbon, including diamond-like carbon (DLC). DLC is excellent as a low-friction or anti-wear coating [8,9] especially in medical applications [10,11] and it is often modified by adding various elements, e.g., Si, Ag, F or Ti [12][13][14]. It can also be used for the production of carbon-based fragmented materials, which are usually described in the literature as flakes or powders [15,16].…”