Tribotechnical Characteristics of Titanium Nitride Coating for High-Load Friction Clutches
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otechnical Characteristics of Titanium Nitride Coating for High-Load Friction Clutches O. Yu. Elaginaa, *, D. O. Kolbasa, A. G. Buklakova, N. Drrb, and L. Drangeib aGubkin
Russian State University of Oil and Gas (National Research University), Moscow, 119991 Russia Center of Competence for Tribology (AC2T research GmbH), Wiener Neustadt, 2700 Austria *e-mail: [email protected]
bAustrian
Received February 3, 2020; revised July 2, 2020; accepted July 7, 2020
Abstract—The results are presented for studies concerning the tribotechnical properties of titanium nitride coatings under cyclic loading, which is typical for heavily loaded friction clutches. Testing was carried out according to the ball-disk scheme with a cyclic application of contact pressure and short-term slippage. The possibilities of studying the tribotechnical characteristics of friction pairs using a vibration tribometer under different combinations of loading and relative displacement parameters have been demonstrated. The obtained experimental data on TiN–steel friction pairs in the course of sliding in the presence of a lubricating medium indicate a high stability of the friction coefficient under cyclic loads. Increasing friction power in the TiN–steel friction pair does not lead to an abruptly dropping friction coefficient. As the relative movement velocity decreases, the friction coefficient increases. The development of friction disks coated with titanium nitride for highly loaded gearboxes should reduce the dynamic loads in the course of operation originating from the destabilization of the friction coefficient and increase the efficiency and service life thereof. Keywords: friction clutch, friction material, friction coefficient, spraying, titanium nitride, wear DOI: 10.3103/S1068366620050086
INTRODUCTION The stability and service life of hydro-tightening friction clutches in gearboxes depends on a large number of factors. Among the most significant factors are maintaining stable friction coefficient under heating the contact surfaces of friction disks, wear resistance in the contact layer of friction disks, and wear particles absent in the lubricating medium [1, 2]. The intense heating of friction surfaces in friction clutches is caused by significant specific loads, which is typical in the case of heavily loaded gears, as well as in the case of prolonged slipping. The surface layer temperature of friction disks under such conditions can amount up to 150–200°С, which leads to a decrease in the friction coefficient by a factor of 2 or more [3, 4]. To achieve smooth movement velocity switching, friction disks should provide a relatively high dynamic friction coefficient at the initial moment of contact, which should be stabilized at the required level regardless of the time of slipping (skidding) of the contacting surfaces and regardless of heating [5]. In addition, providing stable operation of an automatic gearbox depends to a substantial extent on the purity of oil and absence of mechanical impurities, which, in turn, in many respects
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