Function and characteristics of oxide film on slip ringShaanxi asynchronous Xima Motor Co., Ltd. (www.yibusimo. Com) information: the oxide film has very good lubrication performance. The main lubrication layer of the contact surface between the carbon brush and the slip ring is graphite film, which separates the carbon brush and the slip ring, makes the friction between the graphite lubrication layer, reduces the friction coefficient, reduces the generation of friction heat, and reduces the wear of the carbon brush. In many cases, the oxide film is damaged and cannot be rebuilt.
It is found that when the applied voltage is small, the oxide film is broken down. After breakdown, no matter how the current increases, the contact voltage remains constant due to the increase of the conductive point and the expansion of the conductive area. When running on the slip ring, a uniform, moderate and stable oxide film is formed on its contact surface, which is one of the main signs of good motor operation. Because of the existence of the oxide film, the contact characteristics between the carbon brush and the slip ring are changed, the friction is reduced, the wear is reduced and the service life is prolonged. Oxide film is a kind of composite film, its composition is related to the type of carbon brush and the material composition of slip ring. The normal thickness of the oxide film is in the range of 8-100 nm, generally 25 nm. It is found by electron microscope that the contact surface of carbon brush and slip ring is contacted by numerous points, generally, the contact surface is only a few thousandths of the total area of carbon brush. The size of contact area is determined by motor speed, hardness of slip ring material, machining accuracy, deflection, material of carbon brush, pressure on carbon brush, etc