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| Selecting the Right
PTFE Compound |
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| PTFE
fluorocarbon resin performs well in many applications
without filler. In fact, fillers can lessen its
outstanding electrical and chemical properties.
In mechanical applications, however, compounds of
PTFE and inorganic fillers offer improved wear resistance,
reduce creep and initial deformation, and increased
stiffness and conductivity. Hardness is increased,
and the coefficient of thermal expansion is decreased.
Compounds can therefore make it possible to gain
the advantages of PTFE in applications where the
unfilled resin cannot be used. |
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| Glass Fiber
Glass in the form of short fibers is the most widely
used filling material. The most popular compounds
are 15% or 25% glass (by weight). It is sometimes
combined with graphite or MoS2. Glass
has little effect on most of the electrical properties
of PTFE. It resists acids and oxidation, but it
can be attacked by alkali. |
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| Carbon
A typical carbon filler is high-purity coke powder.
It is often used in combination with graphite in
concentrations of 25% to 35% glass (by weight).
Compounds of PTFE and carbon have excellent wear
resistance, both dry and in water. They are compatible
with most chemicals and can carry heavy loads under
rubbing contact. |
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| Graphite
This crystaline form of carbon is used alone or
in combination with glass or amorphous carbon. A
typical compound is 15% graphite by weight. The
addition of graphite helps reduce the wear of soft
metal mating parts and improves frictional and wear
properties when mixed with other fillers. Like other
forms of carbon, it serves well in corrosive environments. |
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| Bronze
Round or irregularly-shaped bronze particles are
often used at 60% by weight, or 55% with 5% MoS2.
Compounds of bronze and PTFE are creep-resistant
and easily machined. They deliver good wear performance,
low friction, and relatively high thermal conductivity. |
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| MoS2
Used in concentrations of approximately 5% by weight
in compounds with glass or bronze, MoS2
can increase surface hardness and lower coefficient
of friction and wear rate. |
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TYPICAL
PROPERTIES OF PTFE |
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Bronze
and Bronze MoS2 - Fortified PTFE |
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Glass
Fiber and MoS2 - Fortified PTFE |
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Filled
PTFE Compounds with Carbon, Graphite and Glass
Fiber |
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