Carbon Filled PTFE
Carbon Filled PTFE (Polytetrafluoroethylene infused with carbon fibers) Slide Bearings, provides a sliding surface with greater compressive strength and durability than standard Virgin (white) PTFE.
Carbon content can be specified and as the carbon content increases the hardness and durability of the sliding surface increase. The standard mixture is 75% PTFE vs. 25% Carbon Filler.
Using the 75 / 25 mixture as an example the change in properties vs. pure PTFE is:
|PTFE||Carbon Filled PTFE|
|Tensile Strength||20 - 30 Mpa||13 - 18 Mpa|
|Elongation||350%||90 - 200%|
|Shore D Hardness||55 - 65||60 - 66|
|Coefficient of Friction||<0.1||0.12 - 0.16|
As shown in the table above the trade off for hardness and durability is a loss of tensile strength and an increase in friction.
The coefficient of friction can be improved by adding Graphite to the composition. Adjusting to a formulation of 75% PTFE x 23% Carbon Filler x 2% Graphite will return the coefficient of friction to approximately 0.3