The problems of resistance to scuffing of heavily loaded lubricated friction joints with WC/C-coated parts
Abstract
Purpose
The purpose of this paper was to explore the mechanisms of scuffing propagation of heavily loaded lubricated friction pair elements coated with low-friction WC/C coating for various material combinations.
Design/methodology/approach
The investigations were performed for low-friction coatings WC/C (a-C:H:W) deposited by the reactive sputtering physical vapour deposition (PVD) process. Experiments were carried out using a four-ball tester with continuously increasing loads. Tests were conducted for the following four material combinations: steel/steel tribosystem (all balls uncoated); steel/coating tribosystem (one upper ball uncoated/three lower balls WC/C-coated); coating/steel tribosystem (one upper ball WC/C-coated/three lower balls uncoated); and coating/coating tribosystem (all balls WC/C-coated).
Findings
The better scuffing resistance is achieved by coating only one element (coating/steel tribosystem) than all elements (coating/coating tribosystem). The description of scuffing propagation for all investigated tribosystems was done. The high scuffing resistance of the coating/steel tribosystem resulted from reducing the adhesion between rubbing surfaces due to low chemical affinity (similarities) between the steel and the coating material and the presence of solid lubricant in the friction zone.
Practical implications
In all cases, when a coating is applied, an increase in scuffing resistance is observed. However, it is better to coat only one element than all. Furthermore, the scuffing resistance for the coating/steel tribosystem is significantly higher than for the steel/coating tribosystem.
Originality/value
The main value of this paper is description of scuffing propagation and revealing the new aspects in application of low-friction WC/C coating for heavily loaded lubricated friction pair elements. The overlapping ratio has been defined as an important factor influencing the scuffing resistance of the coated tribosystems.
Keywords
Acknowledgements
The authors wish to express their thanks to Edyta Osuch-Slomka from ITeE-PIB (Poland) for SEM/EDS measurements and to Maksim Antonov from Tallinn University (Estonia) for his support with tribological experiments and helpful discussions.
Citation
Michalczewski, R., Piekoszewski, W., Tuszynski, W. and Szczerek, M. (2014), "The problems of resistance to scuffing of heavily loaded lubricated friction joints with WC/C-coated parts", Industrial Lubrication and Tribology, Vol. 66 No. 3, pp. 434-442. https://doi.org/10.1108/ilt-01-2012-0001
Publisher
:Emerald Group Publishing Limited
Copyright © 2014, Emerald Group Publishing Limited