Does the self-lubrication of graphite copper sleeve diminish over time?

Under normal working conditions

Under normal working environment and working conditions, the self-lubrication of graphite copper sleeve will not be significantly weakened. This is because the graphite in the graphite copper sleeve has a layered crystal structure, the bonding force between the layers is weak and easy to slide, in the process of relative movement of the shaft and the copper sleeve, the graphite will continue to transfer to the friction surface, forming a stable solid lubrication film.

As long as the surfaces of the shaft and the copper sleeve are not seriously damaged, such as excessive wear, scratches or a large number of intrusions by external impurities, this self-lubricating mechanism can play a long-term and stable role. For example, in some low-speed, low-load general mechanical equipment, graphite copper sleeve can maintain good self-lubricating performance for a long time, equipment friction coefficient and wear can be maintained at a low level.

Special working conditions

High temperature environment: when the working temperature is too high, it may have some effect on the self-lubrication of graphite copper sleeve. Although graphite itself has a high resistance to high temperatures, excessive temperatures may cause the copper alloy matrix to expand and deform, changing the contact state between graphite and shaft. At the same time, high temperatures may also cause changes in the bonding between graphite and copper alloy matrix, affecting the transfer of graphite to the friction surface, which in turn reduces the self-lubricating performance.

High load and high speed working conditions: under high load and high speed working conditions, the friction between the shaft and the copper sleeve increases, and the wear increases. If more than the graphite copper sleeve can withstand the limit, may lead to graphite layer is quickly worn off, or so that the graphite can not be transferred to the wear parts in time to form a lubricating film, so that the self-lubricating performance is weakened.

Harsh media environment: if the graphite copper sleeve work in a strong corrosive medium, a large number of hard particles or strong oxidizing substances in the environment, these substances may erode the surface of the graphite copper sleeve, destroy the structure of the graphite layer, or make the graphite and copper alloy substrate to produce a separation between the final result of the decline in self-lubricating performance. For example, in chemical equipment, if corrosive chemicals come into contact with the graphite bushing, it may affect its self-lubricating performance.