Wear behaviour of carbon-containing tungsten coatings prepared by reactive magnetron sputtering

Abstract

W(1-x)C(x) coatings (with x being in the range of 0.05-0.19) were deposited by reactive magnetron sputtering on to AISI 316 stainless-steel substrates in order to study the influence of the carbon content on the tribological properties of the coating-substrate composite. Knoop microhardness (H(K)), scratch adhesion, pin-on-disc sliding, ball-on-plate impact and abrasive wheel wear tests were performed to evaluate the mechanical and tribological properties of the coatings. X-ray diffraction (XRD) was used for phase- and peak shape parameter analysis, whilst the coating morphology was evaluated by scanning electron microscopy. It was found that all coatings consist mainly of the b.c.c. αW phase. With increasing carbon content from 5 to 19 at.%, an expansion of the αW lattice occurs progressively, associated with an increase in the peak full width at half maximum (FWHM) and a decrease in intensity. The film density and hardness increased with increasing carbon content up to 15 at.%, where hardness values of 4000H(K0.025) were observed. Coatings comprising W(1-x)C(x) with x≤0.08 showed the best abrasive wear resistance and adhesion with no through-coating failure in the wear track for dry pin-on-disc sliding and no crack development around the indentation areas in impact tests after 50 000 impacts against both steel and cemented tungsten carbide balls. W1-xCx coatings (with x being in the range of 0.05-0.19) were deposited by reactive magnetron sputtering on to AISI 316 stainless-steel substrates in order to study the influence of the carbon content on the tribological properties of the coating-substrate composite. Knoop microhardness (HK), scratch adhesion, pin-on-disc sliding, ball-on-plate impact and abrasive wheel wear tests were performed to evaluate the mechanical and tribological properties of the coatings. X-ray diffraction (XRD) was used for phase- and peak shape parameter analysis, whilst the coating morphology was evaluated by scanning electron microscopy. It was found that all coatings consist mainly of the b.c.c. αW phase. With increasing carbon content from 5 to 19 at.%, an expansion of the αW lattice occurs progressively, associated with an increase in the peak full width at half maximum (FWHM) and a decrease in intensity. The film density and hardness increased with increasing carbon content up to 15 at.%, where hardness values of 4000HK0.025 were observed. Coatings comprising W1-xCx with x≤0.08 showed the best abrasive wear resistance and adhesion with no through-coating failure in the wear track for dry pin-on-disc sliding and no crack development around the indentation areas in impact tests after 50 000 impacts against both steel and cemented tungsten carbide balls.