TY - JOUR

T1 - Functionality Investigations of Dry-Lubricated Molybdenum Trioxide Cylindrical Roller Thrust Bearings

AU - Konopka, Dennis

AU - Pape, Florian

AU - Heimes, Norman

AU - Behrens, Bernd-Arno

AU - Möhwald, Kai

AU - Poll, Gerhard

N1 - Funding information: Acknowledgments: The results presented in this paper were obtained within the scope of the priority program “Fluidless Lubrication Systems with high Mechanical Load” (SPP 2074) in project 2, funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG)). Grant number 407673224. The authors gratefully acknowledge the German Research Foundation for their financial support of this project.

PY - 2022/4/26

Y1 - 2022/4/26

N2 - In addition to using conventional lubricants, such as oil and grease, rolling bearings can also be used with a dry lubricant. For example, the use of dry lubricant systems is necessary when the application of oils or greases is not possible (e.g., at high temperatures or in aerospace applications). The requirements of a solid lubricant are to reduce friction and wear of mechanical contact partners. In this work, a molybdenum-based coating system was applied by means of physical vapor deposition (PVD). The coating system consists of a molybdenum (Mo) reservoir with molybdenum trioxide (MoO 3) as the top layer. The MoO 3, which is particularly important for the run-in and the lubricating effect, is intended to continuously regenerate from the reservoir via tribo-oxidation. To determine the friction and wear behavior, cylindrical roller thrust bearings were used. Experiments demonstrated that the lubrication system is effective and that the frictional behavior has been improved. On the one hand, the frictional torque of the rolling bearings has been considerably reduced and, on the other, significantly extended operating times have been determined compared to unlubricated reference experiments. Simultaneously, material analyses have been carried out by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The investigations showed that the MoO 3 was transferred to uncoated bearing components. This improved the tribological behavior and reduced abrasive and adhesive wear.

AB - In addition to using conventional lubricants, such as oil and grease, rolling bearings can also be used with a dry lubricant. For example, the use of dry lubricant systems is necessary when the application of oils or greases is not possible (e.g., at high temperatures or in aerospace applications). The requirements of a solid lubricant are to reduce friction and wear of mechanical contact partners. In this work, a molybdenum-based coating system was applied by means of physical vapor deposition (PVD). The coating system consists of a molybdenum (Mo) reservoir with molybdenum trioxide (MoO 3) as the top layer. The MoO 3, which is particularly important for the run-in and the lubricating effect, is intended to continuously regenerate from the reservoir via tribo-oxidation. To determine the friction and wear behavior, cylindrical roller thrust bearings were used. Experiments demonstrated that the lubrication system is effective and that the frictional behavior has been improved. On the one hand, the frictional torque of the rolling bearings has been considerably reduced and, on the other, significantly extended operating times have been determined compared to unlubricated reference experiments. Simultaneously, material analyses have been carried out by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The investigations showed that the MoO 3 was transferred to uncoated bearing components. This improved the tribological behavior and reduced abrasive and adhesive wear.

KW - dry lubricant

KW - friction

KW - Mo-coating

KW - PVD

KW - rolling bearing

KW - wear

UR - http://www.scopus.com/inward/record.url?scp=85129828794&partnerID=8YFLogxK

U2 - 10.3390/coatings12050591

DO - 10.3390/coatings12050591

M3 - Article

VL - 12

JO - COATINGS

JF - COATINGS

SN - 2079-6412

IS - 5

M1 - 591

ER -