Influence of Magnetron Sputtering Parameters on Mechanical and Tribological Properties of Carbon Nitride Coatings

Abstract

This work is devoted to investigation of mechanical and tribological properties of carbon nitride (CNx) coatings deposited on the titanium IM125 and steel AISI321 substrates by the method of reactive magnetron sputtering of a graphite target at direct current in a mixture of gases argon/nitrogen. As shown, at pressure р = 0.35 Pа, nitrogen concentration in a mixture of gases С = 42−58%, substrate temperature Тsubstr. = 130°С, the highest values of hardness H = 15−20 GPa, modulus of elasticity E * = 120−132 GPa, normalized hardness H/E * = 0.130−0.152, elastic deformation εes = 4.03−4.6% are obtained, indicating increased ductility and wear resistance of the coating under friction. Wear-resistance testing conducted under dry friction by means of the ball−on−disc and ball−section methods show that high wear resistance is found in CNx coatings with the highest carbon ordering, and it is confirmed by high values of normalized hardness H/E * and εes. Testing in blood plasma of titanium IM125 samples with CNx coating in friction pair with chirulen yields low values of friction coefficient and wear intensity of chirulen equal to 0.079 and 0.65 mm/km, respectively.