Changes in the performance of graphite copper sleeves at different temperatures
The performance of graphite copper sleeves will change at different temperatures, which mainly depends on the characteristics of the copper alloy matrix and graphite lubricant. The following are possible performance changes of graphite copper sleeves in different temperature ranges:
1. Low temperature environment (below room temperature)
At low temperatures, many oils and greases become more viscous and may even solidify, resulting in reduced lubrication effectiveness. However, the self-lubricating properties of the graphite copper sleeve are still effective in this case because the graphite lubricant does not rely on liquid lubricant.
Low temperatures may increase the brittleness of the metal material, but this usually does not have a significant impact on the overall performance of the graphite copper sleeve unless the temperature is extremely low.
2. Room temperature environment (about 20°C to 25°C)
This is the most stable performance range of graphite copper sleeves. The interaction between the copper alloy matrix and the graphite lubricant provides good lubrication and wear resistance.
Within this temperature range, the graphite copper sleeve can withstand normal working loads, and the friction coefficient and wear rate are at a low level.
3. Medium temperature (about 100°C to 200°C)
As temperature increases, the copper alloy matrix may decrease slightly in hardness, which may slightly increase friction and wear. However, graphite's lubricating properties are still effective and can help reduce these problems.
Increased temperature may improve the lubrication properties of graphite and reduce the friction coefficient, because graphite transfers more easily at high temperatures and forms a lubricating film on the contact surface.
4. High temperature environment (above 200°C)
In the range of 250°C to 350°C, the graphite copper sleeve can still maintain sufficient strength and lubrication performance, but the thermal expansion coefficient must be considered and the fitting gap between the graphite copper sleeve and the shaft should be appropriately increased to prevent locking.
At high temperatures above 350°C, the strength and hardness of the copper alloy matrix decreases, which may affect the structural integrity and load-bearing capacity of the graphite copper sleeve.
High temperatures may cause a reduction in the performance of graphite lubricants, as graphite begins to oxidize at around 400°C, which may reduce its lubricating effectiveness.
At extremely high temperatures, graphite copper sleeves may require special design or material selection to ensure their performance and safety.
