Study of the Formation of Films of Secondary Structures Upon Sliding of the “Aluminum Alloy–Steel” Friction Pair

• Published in: Surface investigation, x-ray, synchrotron and neutron techniques x-ray, synchrotron and neutron techniques, 2021-11, Vol.15 (6), p.1326-1331
• Main Authors: Muravyeva, T. I., Shkalei, I. V., Shcherbakova, O. O., Zagorskiy, D. L.
• Format: Article
• Language: English
• Subjects: Aluminum alloys; Aluminum base alloys; Antifriction bearings; Chemical elements; Chemical reactions; Chemistry and Materials Science; Friction; Lubrication; Mass transfer; Materials Science; Medium carbon steels; Microscopy; Scanning probe microscopy; Self lubrication; Surfaces and Interfaces; Thin Films; Tribology
• ISSN: 1027-4510; 1819-7094
• DOI: 10.1134/S1027451021060367

The processes, occurring on the contact surface during the friction of the multicomponent antifriction aluminum alloy Al–20%Sn–5%Si (shoe) against the steel St45 (roller), in particular the effect of self-lubrication, are studied. A comprehensive technique for microscopic surface studies is used, including scanning electron microscopy and scanning probe microscopy. A correlation is established between the data obtained by the two microscopy methods. Both the initial surface of the samples and the surface after tribological tests under extreme friction conditions (without lubrication) are studied. Structural changes of the surface during friction are evaluated. It is established that during friction, a soft phase component of the alloy is released and the mass transfer of chemical elements from one contact surface to another occurs. Studying the surfaces of the contact pair makes it possible to evaluate the specific features of mass transfer between the shoe and the roller. It is revealed that under minimal loading conditions, the self-lubrication effect slightly appears and there is an intensive transfer of iron from the roller surface to the shoe surface. With an increase in the load (within certain ranges), the release of the soft phase increases significantly, which changes the nature of the surface and the processes occurring on it. It is shown that as a result of complex mechanical and physical-chemical processes, a film of secondary structures is formed on the contact surface. This film, depending on the friction conditions, can play a different role: not only protecting the surface from destruction, but also contributing to scoring.