Триботехнічні властивості сплаву БрО3А3 в умовах сухого тертя

Abstract

Currently, lead and tin bronzes are most often used for the production of bearings, which is due to their high level of tribotechnical properties and reliability in operation. At the same time, the ban in the European Union on the use of lead in any products led to the need to find environmentally safe bronzes with a similar or increased level of tribotechnical properties. A promising way to solve this problem is BrO3A3 bronze, the microstructure of which fully meets the requirements for bearing alloys. However, to date, the tribotechnical properties of BrO3A3 bronze have not been investigated. Therefore, the task of researching the tribotechnical properties of cast bronze BrO3A3 as a bearing alloy is urgent. The purpose of the work is to establish the values of relative wear resistance and friction coefficient, as parameters by which it is possible to recommend the use of cast bronze of the BrО3A3 brand as an antifriction material. Wear resistance tests according to the "disk-disk" scheme were carried out in accordance with the requirements of State and International standards on a mod machine. SMC-2 under a load of 45 kg (441 N) in friction-rolling conditions with a slip of 10% at room temperatures. Tribotechnical tests of the samples of the investigated bronzes according to the "ball-disc" scheme were carried out under dry friction-sliding conditions on the "Micron-tribo" friction machine in accordance with the International Standards DIN 50324 and ISO 20808. The microstructure was studied using a NEOPHOT 21 optical microscope with a magnification of up to 1000 times. According to the results of the study, it was found that compared to BrO5C5C5 and BrA9Zh3L bronzes, BrO3A3 bronze is characterized by a higher level of resistance to wear during dry rubbing, which is due to the presence of a hard but plastic phase in its structure β-Cu5Sn. The value of the coefficient of friction of BrO3A3 bronze coincides with the similar coefficient of BrO5C5S5 bronze and is lower than that of pure copper and bronzes of BrO8, BrA5 and BrA9Zh3L brands. At the same time, with an increase in the content of both tin (from 3 to 4% by mass) and aluminum (from 3 to 4% by mass), the coefficient of friction of BrO3A3 bronze decreases from 0.28 to 0.25. The research results are a reason to recommend BrO3A3 bronze as a tribotechnical material in friction nodes to replace not only lead bronzes and BrO5C5S5 bronzes, but also BrA9Zh3L bronzes.