FRICTION MECHANISM OF POLYAMIDE-6 AGAINST TIN BRONZE UNDER THE BOUNDARY LUBRICATION CONDITIONS

The friction of polyamide-6 against tin bronze BrO5Tz5S5 is investigated. The experiments on a friction machine MI-1 according to the scheme of «a stationary ring against a rotating roller» arranged by both direct and reverse friction pair are carried out. The reverse pair is tested under both water lubrication and dry condition, whereas the direct pair is tested just under water lubrication. The lubrication is implemented by partially immersing the roller into the tray filled with fresh water. At first every friction pair underwent breaking-in with the load equal to that taking place on the surface of real stern-tube bearings during their breaking-in. Then the friction moment is recorded at different loads. When dealing with dry friction, the breaking-in, however, is implemented under water lubrication condition mentioned above, then the roller and the ring are dried thoroughly with paper napkins and fixed again exactly on the previous position. It turned out that friction in polyamide-tin bronze pair under boundary lubrication with water does not depend on the initial roughness of both polyamide and bronze element. And the friction does not depend on the friction scheme (direct or reverse pair) either. Even at comparatively high pressure, characteristic for the real stern-tube bearings breaking-in, the water comes in between the rubbing surfaces. The friction under lubrication condition is caused completely by adhesion, which, in its turn, results from dispersion interaction between adsorbed water films (under water lubrication) or immediately rubbing surfaces (under dry condition). Application of water reduces the friction by 25 % compared to the dry friction.

stern-tube bearing, friction machine, polyamide, tin bronze, fresh water, boundary lubrication, hydrodynamic lubrication, friction, wear, roughness, adhesion

1. Лысенков П. М. Экологически чистая трибосистема судового движительного комплекса / П.М. Лысенков // Трение, износ, смазка. - 2019. - Т. 21. - № 80 [Электронный ресурс]. - Режим доступа: http://tribo.ru/netcat_files/313/208/h_c910836d8f751ffdeb6e361db6902b95 (дата обращения: 25.02.2020).

2. Litwin W. Experimental research on marine oil-lubricated stern tube bearing / W. Litwin // Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology. - 2019. -Vol. 233. - Is. 11. - Pp. 1773-1781. DOI: 10.1177/1350650119846004.

3. Litwin W. Water-lubricated bearings of ship propeller shafts - problems, experimental tests and theoretical investigations / W. Litwin // Polish Maritime Research. - 2009. - Vol. 16. - Is. 4. - Pp. 41-49. DOI: 10.2478/v10012-008-0055-z.

4. Roldo L. Design and Materials Selection for Environmentally Friendly Ship Propulsion System / L. Roldo, Komar, N. Vulić // Strojniški vestnik - Journal of Mechanical Engineering 2013. - Vol. 59. - Is. 1. - Pp. 25-31. DOI: 10.5545/sv-jme.2012.601.

5. Wu Y. Effects of Typical Physical Properties on Tribological Behaviors of Three Kinds of Polymer Materials for Water-Lubricated Bearings / Y. Wu, X. Bai, C. Yuan, C. Dong, L. Zhang, S. Liu // Tribology Transactions. - 2019. - Vol. 62. - Is. 6. - Pp. 1019-1028. DOI: 10.1080/10402004.2019.1640916.

6. Guo Z. Study on influence of micro convex textures on tribological performances of UHMWPE material under the water-lubricated conditions / Z. Guo, X. Xie, C. Yuan, X. Bai, // Wear. - 2019. - Vol. 426-427. - Pp. 1327-1335. DOI: 10.1016/j.wear.2019.01.010.

7. Fuming K. Tribological Properties of Nitrile Rubber/UHMWPE/Nano-MoS Water-Lubricated Bearing Material Under Low Speed and Heavy Duty / K. Fuming, Z. Xincong, H. Jian, Z. Xiaoran, W. Jun // Journal of Tribology. - 2018. - Vol. 140. - Is. 6. DOI: 10.1115/1.4039930.

8. Gebretsadik D. W. Friction and wear characteristics of PA 66 polymer composite/316L stainless steel tribopair in aqueous solution with different salt levels / D. W. Gebretsadik, J. Hardell, B. Prakash // Tribology International. - 2020. - Vol. 141. - Pp. 105917. DOI: 10.1016/j.triboint.2019.105917.

9. Григорьев А. К. Стендовые испытания подшипника скольжения из антифрикционного материала Торплас фирмы «Thordon Bearings Inc.» / А. К. Григорьев, В. Н. Звягинцев // Вопросы материаловедения. - 2006. - № 2 (46). - С. 166-172.

10. Мамонтов В. А. Анализ износов капролоновых втулок дейдвудных подшипников гребного вала / В. А. Мамонтов, А. И. Миронов, Ч. А. Кужахметов, А. А. Халявкин // Вестник Астраханского государственного технического университета. Серия: Морская техника и технология. - 2012. - № 1. - С. 30-35.

11. Рубин М. Б. Подшипники в судовой технике: cправ. / М. Б. Рубин, В. Е. Бахарева. - Л.: Судостроение, 1987. - 344 с.

12. Гаркунов Д. Н. Триботехника (конструирование, изготовление и эксплуатация машин) / Д. Н. Гаркунов. - М.: Изд-во МСХА, 2002. - 632 с.

13. Крагельский И. В. Основы расчетов на трение и износ / И. В. Крагельский, М. Н. Добычин, В. С. Комбалов. - М.: Машиностроение, 1977. - 526 с.

14. Мур Д. Основы и применения трибоники / Д. Мур. - М.: Мир, 1978. - 487 с.

15. Ахматов А. С. Молекулярная физика граничного трения / А. С. Ахматов. - М.: Физматгиз, 1963. - 472 с.