Antifriction Properties of a Diamond-Like Coating and Titanium Nitride in Model Lubricating Media

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ABILITY, STRENGTH, AND WEAR RESISTANCE OF MACHINES AND STRUCTURES

Antifriction Properties of a Diamond-Like Coating and Titanium Nitride in Model Lubricating Media I. A. Buyanovskiia,*, V. D. Samusenkoa, and V. A. Levchenkob a

Blagonravov Institute of Mechanical Engineering, Russian Academy of Sciences, Moscow, 101830, Russia b Moscow State University, Moscow, 119991 Russia *e-mail: [email protected] Received January 27, 2020; accepted March 27, 2020

Abstract—Antifriction properties have been studied for a diamond-like coating (DLC) and titanium nitride, used as an intermediate layer to improve adhesion. The physical and mechanical properties of the coatings have been determined, and the tribotechnical properties thereof have been evaluated in an inactive lubricating medium, as well as in lubricating media with surfactant and chemically-active additives. The studied diamond-like coating causes the wear resistance of the surface to increase and can significantly reduce the coefficient of friction. The lubricating medium does not significantly affect the antifriction properties of the diamond-like coating. Keywords: DLC, diamond-like coatings, titanium nitride, antifriction properties, friction coefficient, wear, additives. DOI: 10.3103/S1052618820040056

INTRODUCTION The application of nanostructured carbon coatings onto the working surfaces of steel parts for friction units operating in a boundary lubrication mode enhances the antifriction and antiwear characteristics of lubricating media in an efficient way such as introducing known tribologically active additives into these media [1]. Diamond-like coatings (DLCs) make it possible to expand the temperature range of the lubricating media serviceability and to provide a significant decrease in the coefficient of friction and/or in the content of tribologically active additives in lubricating oils. Therefore, the use of diamond-like coatings can be considered as a key to an increase in the efficiency of lubricants for various purposes [2]. A serious disadvantage of such coatings consists in the high level of internal stresses in the coating layer [3], which predetermines a relatively low level of their adhesion to the steel substrate. Thus, the adhesion of the coatings to the substrate in some cases is insufficient (in some cases peeling of the coating has been observed); the antiwear properties of such coatings at a high contact pressure do not meet the requirements for parts of heavily loaded friction units. The elimination of this disadvantage could be accomplished by using multilayer coatings, the inner layer of which provides the required adhesion between the coating and the substrate, whereas a thin layer of a diamond-like coating is applied onto the top of this layer [4]. The analysis performed has shown that coatings that provide a high adhesion level of the two-layer coating to the substrate should have a high level of hardness and wear resistance and a satisfactory corrosion resistance. They should also be serviceable in a wide operating temperature range. O