Carbon Filled PTFE Compounds
Carbon filled grades have improved wear characteristics as compared to virgin PTFE. They have reduced creep, increased hardness, and good electrical conductivity. They also have elevated thermal conductivity. Performs well in water and steam applications.
Carbon has good chemical resistance to corrosive environments. It exhibits good initial wear and rubbing or sliding contact characteristics, both dry and water applications. It is frequently used in piston rings to reduce cylinder wall wear by entrapping abrasive foreign particles in their relatively soft surfaces.
Carbon filled PTFE compounds are used mostly in chemical and mechanical applications. The low friction property of the filler reduces initial wear and starting friction. This filler displays higher load carrying capabilities in rubbing contact applications such as piston rings and seals requiring low static break away efforts. Carbon filled PTFE reduces wear of soft metal mating parts and serves well in corrosive environments. This compound has a long life without lubrication. The use of carbon greatly enhances the compressive strength.
Graphite Filled PTFE Grades
These are Glossy black non-abrasive compounds for softer mating surfaces, such as stainless steel. This material has excellent chemical resistance and is FDA, USDA and NSF compliant. It has a high resistance to deformation under load and good thermal and electrostatic dissipation. This material has a maximum operating temperature of 300 deg C.
Graphite filled PTFE compounds offer the same results as Carbon filled PTFE. However, Graphite filled PTFE has a much lower compressive strength. This compound is good where aluminum and water are concerned.
Graphite filled grades releases black wear debris over time and should not be used in ultra-dry, vacuum applications or where electrical insulation is desired.
Glass Fiber filled PTFE compounds
Glass filled PTFE is the most commonly used filler and has only a slight effect on both the chemical and electrical properties, yet adds greatly to the mechanical properties of the unfilled material. This fibrous filler offers the best balance of chemical, electrical and mechanical properties of all other materials and is used in applications requiring low cold flow and high compressive rigidity. Higher glass content compounds increase wear resistance. Glass filled compounds can be very abrasive.
These compounds are chemically inert (except its reactivity with hydrofluoric acid and strong bases), and reduced creep. The addition of Glass fiber also improves dimensional stability and Heat deflection Temperature of the compound. They perform well in oxidizing environments and have improved wear characteristics over virgin PTFE.
Addition of glass improves compressive properties by as much as 40% and improves wear resistance greatly. Applications include Piston rings, Shaft bearings, Valve seats , Shaft Seals and gaskets.
Bronze filled PTFE grades
Bronze filled PTFE offers a gain of several desirable property characteristics such as hardness, low wear, higher compressive strength, better dimensional stability, higher thermal conductivity, low creep and cold flow. This compound is used in the steam service and eliminates valve sticking after periods of inactivity. Turning torque required to open is low and lubrication unnecessary. Drawbacks of this filler are that it should not be used in corrosive service or against an aluminum mating service or in the presence of water. Bronze filled PTFE is especially designed for heavy duty mechanical service such as bearing applications.
Reduced deformation under load raises thermal and electrical conductivity of PTFE. This filler has better wear, creep resistance, and higher thermal conductivity than glass fiber with PTFE.
Useful in applications which undergo high mechanical loads or high-speed rubbing contacts where the bronze filler supplies the strength and conductivity to carry.
Molybdenum Sulphide filled PTFE
This filler is used frequently in combination with others to increase surface hardness, stiffness, and to reduce the starting coefficient of friction and steady-state wear. Its effect on electrical and chemical properties is negligible. This material is excellent in dry gas with better wear
Glass Moly Filled PTFE
Excellent wear and heat resistance high pressure applications good in hydraulic, steam, and water. Abrasive in rotary service against soft metals.
Polyimide filled PTFE
Excellent in dry service with low wear rate in vacuum and inert gases. Very low abrasion to dynamic mating surfaces
Pigmented PTFE materials contain pigment in addition to other fillers. The pigments can add to the wear and compressive properties to previously existing compounds. The pigments also aid in applications where color coding is needed. Typical applications requiring these materials are shaft seals, piston rings and cups.
Stainless Steel Filled PTFE
Stainless Steel filled PTFE compounds are used for seats and seals requiring high heat and steam applications. This compound is also used in many applications involving food processing.