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In the aerospace industry’s constant focus on enhancing aircraft safety, performance and fuel efficiency, fluoropolymers stand out as exceptional aerospace materials. With their unique combination of high strength, low weight and remarkable durability, fluoropolymers can significantly improve the operation, durability and lifespan of critical aerospace components.
An aircraft must have strong components to withstand the high stress, forces and loads it will experience over its life cycle. At the same time, weight reduction is a top priority of the aviation industry in order to achieve greater fuel efficiency and strict emission targets. Advanced aerospace materials are necessary to meet these demands.
Fluoropolymers can withstand extreme temperatures without compromising structural integrity. They also resist exposure to extreme environments and chemically aggressive fuels that can erode other materials. Their high-performance characteristics enable lighter composites while maintaining high strength-to-weight ratios.
What is a Fluoropolymer?
A fluoropolymer is a special type of polymer containing fluorine atoms that shield the polymer chain to prevent the permeation of extreme temperatures and harmful elements. Fluorine provides exceptional resistance characteristics against chemicals, oils, heat, weather and fuel.
Components operating in aerospace environments face exposure to extreme chemicals such as jet fuels. They also face pressures ranging from 20,000 psi, extreme temperatures, g-forces and weightlessness. The robust and lightweight properties of fluoropolymers make them indispensable aerospace materials for a range of applications such as fuel and hydraulic system components, seals, oil lines, O-rings, gaskets and paints.
Types of Fluoropolymers
Different types of fluoropolymers are available on the market. AGC Chemicals Americas offers the broadest range of high-performance fluoropolymers in the world including AFLAS® fluoroelastomers, Fluon® fluoropolymer resins, Fluon+™ Filled PTFE Compounds, Fluon+ Melt Processable Compounds and LUMIFLON® FEVE resins. These materials enhance the quality and durability of bearings, seals, cables, coatings and other components used in the aerospace industry.
AFLAS FFKM Perfluoroelastomers
Light weighting in aerospace applications is one of the most important factors for overall performance and efficiency of aircraft. There are two elastomeric options to achieve lighter weight components when performance matters.
AFLAS FFKMs are perfluorinated elastomers that have the highest performance of any other elastomer material. They have outstanding heat and chemical resistance which can suitably be used for o-rings and seals in extremely harsh and aggressive environments. AFLAS FFKMs exhibit the ultimate in sealing performance in critical applications such as aerospace seals, aircraft piston rings and seal rings for aircraft engines. Certain grades can achieve desirable Shore A hardness levels without the need for fillers which contributes to reducing weight. Furthermore, due to their outstanding resistance to ozone and gear oils, as well as wide temperature ranges (-9°C-300°C), AFLAS FFKMs are durable and safe solutions for aerospace materials.
AFLAS FEPM type elastomers are unique in that they are in a class by themselves, chemically speaking. They exhibit the many qualities and characteristics of FFKM type elastomers, but are much more cost effective. While there are some temperature limitations with FEPM type, light weighting aircraft components can still be achieved particularly with extrudable grades used for high voltage cable coatings.
Light weight cable coating constructions with high performance have become a necessity in the aerospace industry. AFLAS is a durable, flexible, high temperature (200°C) electrical insulation rubber that allows for thinner wire insulation at equivalent performance levels without the necessity of fillers found in XL-PE constructions.
Fluon Fluoropolymer Resins
Fluoropolymer resins have many desirable and unique characteristics which make them ideal for use as aerospace materials. Currently there are no viable alternatives that offer the same combination of properties that fluoropolymer resins can offer:
- Flame retardance and fire resistance
- Excellent weatherability
- Chemical and temperature resistance
- Non-wetting and non-sticking properties
- Superior dielectric properties
Most commonly, PTFE and ETFE are used for insulation of wire and cable in electronics applications where improved signal quality and durability are required to ensure successful transmission of critical data throughout the aircraft, whether it is to improve in-flight connectivity and entertainment systems, avionics and antenna systems, engine sensing and power, or cabin management systems.
Fluon+ Filled PTFE Compounds
PTFE (polytetrafluoroethylene) has excellent thermal and electrical insulation properties and a low coefficient of friction. When combined with fillers such as glass, carbon, graphite, polyimide and polyphenylene sulfide (PPS), its properties are enhanced with added lubricity, thermal conductivity, wear and creep resistance or electrical conductivity.
AGC compounds Fluon+ filled PTFEs to meet specific needs. For example:
- Carbon-filled PTFE improves compression strength, hardness and wear properties. Adding carbon can make PTFE between two and eight times more effective against thermal expansion and up to 1,000 times more resilient to wear damage. These compounds are used to manufacture gaskets, compressor rings, piston rings, seals and more.
- Glass-filled PTFE improves durability and compressive strength while reducing creep resistance. The higher the glass content, the greater the increase in durability and compressive strength. Glass-filled PTFE compounds operate at temperatures from -268 °C to +260 °C in chemical service, ranging from liquid oxygen to fuming nitric acid.
- Graphite-filled PTFE offers similar benefits to carbon compounds but with a lower coefficient of friction that makes them ideal for moving parts such as gears, bearing and hydraulic systems. Often, it is blended with other fillers to combine benefits.
- Polymer-filled PTFE (polyimide, PPS) compounds provide excellent dimensional and thermal stability, improved wear and abrasion properties, as well as improved deformation and extrusion resistance.
Fluon+ Filled PTFE Compounds are used as aerospace materials for a variety of critical seals and components for landing gear and flight control systems, engines, brakes, fuel and hydraulic utility systems.
Fluon+ Melt Processable Compounds
These compounds enhance the properties and add pigment to a range of fluoropolymers including FEP (fluorinated ethylene propylene), ETFE (ethylene tetrafluoroehylene), PFA (perfluoroalkoxy alkanes), PVDF (polyvinylidene fluoride) and ECTFE (ethylene-chlorotrifluoroethylene). They enhance properties related to adhesion, flexibility, mechanical strength, chemical resistance and conductivity.
Aerospace materials made with Fluon+ MPC compounds have increased mechanical properties at elevated temperatures and are inherently flame retardant. These compounds also are utilized to manufacture release film and vacuum bagging materials for aerospace composites.
There are five different groups of melt processable compounds used for aerospace materials:
- Cross-linkable compounds contain a cross-linking agent that enhances mechanical properties such as scrape abrasion, cut-through resistance and tensile strength. They are commonly required for insulating aerospace cables and airframe wires.
- Flexible AR compounds are based on a modified ethylene/ETFE copolymer and a fluoroelastomer. These grades maintain desirable properties of EFTE in a more flexible form. They are used in aerospace wire and cable applications.
- Adhesive-grade compounds are modified ETFE compounds that exhibit high permeation resistance to many fluids and gases, especially aircraft fuels. Adhesive materials combined with conductive functionality are used to control heat and static electricity of hose and tubing exposed to aerospace fluids.
- Masterbatches are used for color coding of wire insulation, tubing, films and injection molded parts. They have a superior surface finish color consistency and dispersion at high-speed extrusion rates. Laser marking grades are another way to distinguish wire coatings with MIL-spec grades for example.
- Modified plastics are engineered plastics such as PEEK and PPS that are modified with proprietary fluoropolymer and compounding technology. The fluoropolymer modification improves the impact and wear resistance of the PEEK and PPS resins, as well as the physical and electrical properties.
LUMIFLON FEVE Resins
LUMIFLON fluoroethylene vinyl ether-based coatings can reduce maintenance costs in the aerospace market by as much as 50% over the life of the plane, in addition to substantially reducing the loss of revenue during scheduled repainting.
Aircraft coated with LUMIFLON resins typically require no repainting for at least eight years, maintaining outstanding appearance and a durable surface that allows for easy cleaning. In contrast, acrylic urethanes begin to fade and chalk after only three years and require repainting after five.
LUMIFLON resins have been used worldwide to formulate aerospace coatings for both military and commercial aircraft. The fluoropolymer resins are offered in high solids solvent based products, but also come in environmentally friendly solid resins, allowing the formulation of low-VOC and HAPS-free coatings.
The alternating structure of LUMIFLON FEVE resins protects the coating from degradation by UV rays, chemicals, and other environmental hazards.
The future of aircraft technology relies on advanced aerospace materials like fluoropolymers that can enhance the performance of critical components while reducing their density. Fluoropolymers are one of the only materials that combine high-temperature performance, chemical inertness and low coefficient of friction. Compounds of fluoropolymers that combine the benefits of two or more materials can simplify and lower the cost of production while opening the door to new applications.
As different grades and formulations of fluoromaterials have distinct properties and benefits, AGC can guide you in choosing one that offers the optimum benefits for your application. Talk to our experts now.
