Hello, my first post. What happens? I'm assuming it's not as good as straight oil. But is it faster than straight graphite?
Curious about mixing graphite and oil
- Thread starter CastleCrasher
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As everyone has said, don't mix the two, it will be slow.
Oil and graphite work on two completely different principles, and do not work together at all.
Graphite is a surface treatment, where friction is reduced as the layers of carbon molecules in between the two surfaces slide over each other easily due to weak van der waals forces (inter-molecular forces between molecules), providing a low coefficient of friction.
Oil is different, as it forms a hydrodynamic bearing where, when spinning fast enough, fluid forces lift the axle off the bore surface, and the two surfaces do not directly contact each other at all. Instead the axle floats on a thin film of oil which flows underneath it, pushing it upwards away from the surface. This surface separation can be incredibly small in some cases; I simulated less than 0.3 mils (<0.0003") for a pinewood derby car.
Carbon is one of the reasons your used motor oil turns black, it is an oil impurity.
Mix a tiny amount of graphite in with the oil and you just made dirty oil. Chunks of graphite will be interfering with the flow of the oil through the tiny fluid channel between the wheel and axle.
Add more graphite and you get high carbon oil "sludge" as Brian states, where neither one is able to lubricate properly. Oil can't flow well, as you have a paste instead of a fluid, therefore you have no hydrodynamic bearing (No oil lubrication). Plus the inter-molecular forces between oil and graphite are MUCH higher than those of graphite alone, so your graphite does not lubricate as intended either.
Oil and graphite work on two completely different principles, and do not work together at all.
Graphite is a surface treatment, where friction is reduced as the layers of carbon molecules in between the two surfaces slide over each other easily due to weak van der waals forces (inter-molecular forces between molecules), providing a low coefficient of friction.
Oil is different, as it forms a hydrodynamic bearing where, when spinning fast enough, fluid forces lift the axle off the bore surface, and the two surfaces do not directly contact each other at all. Instead the axle floats on a thin film of oil which flows underneath it, pushing it upwards away from the surface. This surface separation can be incredibly small in some cases; I simulated less than 0.3 mils (<0.0003") for a pinewood derby car.
Carbon is one of the reasons your used motor oil turns black, it is an oil impurity.
Mix a tiny amount of graphite in with the oil and you just made dirty oil. Chunks of graphite will be interfering with the flow of the oil through the tiny fluid channel between the wheel and axle.
Add more graphite and you get high carbon oil "sludge" as Brian states, where neither one is able to lubricate properly. Oil can't flow well, as you have a paste instead of a fluid, therefore you have no hydrodynamic bearing (No oil lubrication). Plus the inter-molecular forces between oil and graphite are MUCH higher than those of graphite alone, so your graphite does not lubricate as intended either.
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