Effect of organic acid concentration in lubricant on tribological characteristics of friction couple

Introduction. The possibility of using monocarboxylic acids as a lubricant composition additive, and the effect of their concentration in lubricant on the evolution of the friction factor of a brass-steel couple, as well as the morphology of the film surface under friction is considered. The work objective is to study the effect of the concentration of carboxylic acids in the lubricant composition on the evolution of the friction factor of copper – steel alloy.

Materials and Methods. Tribological studies of a brass-steel friction couple in aqueous solutions of monocarboxylic acids with the concentrations of 0.025; 0.05; 0.1; 0.2; 0.5 mol/l are carried out. Using scanning electron microscopy, we have studied the morphology of the servovite film surface that is formed on a steel disk after frictional interaction of a brasssteel couple in aqueous solutions of acids with the concentration of 0.1 mol/l.

Research Results. Tribological characteristics of the brasssteel tribocoupling in aqueous solutions of carboxylic acids of various concentrations are studied. The optimum acid concentration in the lubricant composition is specified. Herewith, a selective transfer and a wearless friction regime are implemented under friction of the brass 59–steel 40X couple. A decrease in the friction ratio to 0.009 and 0.007 is found out under friction in aqueous solutions of valeric and caproic acids, respectively. The formation of an anti-friction film on the steel surface is identified through the scanning electron microscopy. It is established that the film formed in an aqueous solution of caproic acid has a denser structure in comparison with the film formed under friction in aqueous solutions of butyric and caproic acids.

Discussion and Conclusions. Thus, the tribological studies of a brass-steel friction couple in aqueous acid solutions show that the optimum molar acid concentration in the lubricant composition is 0.1 mol/l. At this acid concentration, the values of the friction factor characteristic of the wearless mode are attained.

1. Calhoun, S. F. Antiwear and extreme pressure additives for greases, Tribology Transactions, 1960, vol. 3, pp. 208—214. DOI: 10.1080/05698196008972405

2. Ettefaghi, E., Ahmadi, H., Rashidi, A., Mohtasebi, S. S., Alaei, M. Experimental evaluation of engine oil properties containing copper oxide nanoparticles as a nanoadditive, International Journal of Industrial Chemistry, 2013, vol. 4, pp.1–6. DOI: 10.1186/2228-5547-4-28

3. Wu, Y., Tsuia, W., Liub, T. Experimental analysis of tribological properties of lubricating oils with nanoparticle additives. Wear, 2007, vol. 262, pp. 819–825. DOI: 10.1016/j.wear.2006.08.021

4. Su, F., Chen, G., Huang, P. Lubricating performances of graphene oxide and onion-like carbon as waterbased lubricant additives for smooth and sand-blasted steel discs. Friction, 2018, pp. 1–11. DOI: 10.1007/s40544-018-0237-3

5. Кужаров, А. С. Нанотрибология водных растворов карбоновых кислот при трении бронзы по стали / А. С. Кужаров [и др.] // Инновации, экология и ресурсосберегающие технологии : материалы XI междунар. науч.-техн. форума. — Ростов-на-Дону, 2014. — С. 712–717.

6. Бурлакова, В. Э. Влияние природы органической компоненты на триботехнические свойства системы «бронза-водный раствор карбоновой кислоты-сталь» / В. Э. Бурлакова [и др.] // Вестник Донского гос. техн. ун-та. — 2015. — Т. 15,№. 4 (83). — С. 63–68. DOI: 10.12737/16067

7. Yu, H. et al. Tribological properties and lubricating mechanisms of Cu nanoparticles in lubricant. Transactions of Nonferrous Metals Society of China, 2008. vol. 18, no. 3, pp. 636–641. DOI: 10.1016/S1003-6326(08)60111-9

8. Hu, Z.S, Lai, R., Lou, F., Wang, L., Chen, Z., Chen, G., et al. Preparation and tribological properties of nanometer magnesium borate as lubricating oil additive. Wear, 2002, vol. 252, pp. 370–374. DOI: 10.1016/S0043-1648(01)00862-6

9. Rastogi, R., Yadav, M., Bhattacharya, A. Application of molybdenum complexes of 1-aryl-2,5-dithiohydrazodicarbonamides as extreme pressure lubricant additives. Wear, 2002, vol. 252, no 9–10, pp. 686–692. DOI: 10.1016/S0043-1648(01)00878-X

10. Kragelsky IV, Alisin VV. Friction wear lubrication: tribology handbook. Elsevier; 2016, P. 263.

11. Бурлакова, В. Э. Трибоэлектрохимия эффекта безызносности. — Изд. центр ДГТУ, 2005. — 211 с.

12. Burlakova, V. E., Milov, A. A., Drogan, E. G. Nanotribology of Aqueous Solutions of Monobasic Carboxylic Acids in a Copper Alloy‒Steel Tribological Assembly. Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques, 2018, vol. 12, no. 6, pp. 1108–1116. DOI: 10.1134/S1027451018050427

13. Бурлакова, В. Э. Влияние состава смазочной среды на структуру поверхностных слоев формирующейся при трении сервовитной пленки / В. Э. Бурлакова [и др.] // Поверхность. Рентгеновские, синхротронные и нейтронные исследования. — 2019. — № 4. DOI: 10.1134/S0207352819040061

14. Myshkin, N. K. Friction transfer film formation in boundary lubrication / N. K. Myshkin. Wear, 2000. vol. 245, Iss. 1-2, pp. 116–124. DOI: 10.1016/S0043-1648(00)00472-5

15. Bulgarevich, S. B. Boiko, M. V., Feizova, V. A., Akimova, E. E. Effect of pressure on chemical reactions in the zone of direct friction contact of systems with selective transfer. Journal of Friction and Wear, 2011, vol. 32, Iss. 3, pp. 145–149. DOI: 10.3103/S1068366611030020

16. Бурлакова, В. Э. Механические свойства сервовитных пленок, формирующихся при трении в водных растворах карбоновых кислот / В. Э. Бурлакова [и др.] // Вестник Донского гос. техн. ун-та. — 2018. — Т. 18, №. 3.— С. 280–288. DOI: 10.23947/1992-5980-2018-18-3-280-288

17. Бурлакова, В. Э. Влияние наноразмерных кластеров меди на триботехнические свойства пары трения сталь-сталь в водных растворах спиртов / В. Э. Бурлакова, Ю. П. Косогова, Е. Г. Дроган // Вестник Донского гос. техн. ун-та. — 2015. — Т. 15, № 2(81). — С. 41–47. DOI: 10.12737/11590

18. Бурлакова, В. Э. Трибологические возможности пары трения латунь-сталь в водных растворах органических кислот / В. Э. Бурлакова, Е. Г. Дроган, Д. Ю. Геращенко // Трибология-машиностроению : труды XII междунар. науч.-техн. конф., посвященной 80-летию ИМАШ РАН. — Ижевск, 2018. — С. 92–95.

19. Мухортов, И. В. Полимолекулярная адсорбция смазочных материалов и ее учет в теории жидкостного трения / И. В. Мухортов // Вестник Южно-Уральского государственного университета. Серия: Машиностроение. — 2011. — №. 31 (258). — С. 62–67.

20. Буяновский, И. А. Ориентационная упорядоченность граничных слоев и смазочная способность масел / И. А. Буяновскийи, З. В. Игнатьева, В. А. Левченко, В. Н. Матвеенко // Трение и износ. — 2008. — Т. 29, №. 4. — С. 375–381.

21. Новоселова, М. В. Трибологические свойства тонких пленок жирных кислот / М. В. Новоселова, М. П. Вильмс // Вестник Тверского государственного университета. Серия: Физика. — 2011. — №. 15. — С. 86–91.

22. Garkunov D. N. Scientific Discoveries in Tribotechnologies. No-wear effect under friction: Hydrogen wear of metals. – 2007.