Together with researchers from the University of Louisville and NASA’s Glenn Research Center, the Materials and Manufacturing Directorate at the Air Force Research Laboratory (AFRL) are looking into high-temperature polymer 3D printing for aerospace applications.
Located at Wright-Patterson Air Force Base (WPAFB) near Dayton, Ohio, AFRL researchers are bringing the heat to the kitchen, and have successfully 3D printed carbon fiber-reinforced polymer composite parts capable of the highest temperature to date – effectively teeing things up for achieving next-generation, cost-efficient Air Force manufacturing needs.
Dr. Hilmar Koerner, a scientist on the Polymer Matrix Composite Materials and Processing Research Team and the force behind this discovery, said, “This is an extremely impactful breakthrough in composite material additive manufacturing. These 3-D printed parts can withstand temperatures greater than 300 degrees Celsius, making them potentially useful for turbine engine replacement parts or in hot areas around engine exhaust.”
Researchers working to develop next-generation applications with 3D printing for the USAF have a lot of use for polymer matrix composites, because they are lightweight and can hold up under extreme conditions in high-temperature environments – two very important features when it comes to 3D printing parts for aircraft engines. These materials can also help with reducing fuel consumption while increasing aircraft range, which can lower long-term operating costs as well.
The state-of-the-art material consists of a high-temperature thermoset resin, which is infused with carbon fiber filaments. Most polymer composites are made of a fiber, like glass, that’s been embedded in a matrix or resin made from epoxy, or a similar material. The resulting material is stronger, due to the fact that the embedded fibers actually reinforce the matrix itself.
Using selective laser sintering (SLS) technology to experiment with high-temperature polymer resins, Dr. Koerner and the rest of the research team discovered that while they could 3D print the polymers successfully, the material would melt into a useless puddle once the pieces were removed from the powder bed for post-processing.
Dr. Koerner then came up with the idea to use carbon fiber as a filler in the resin material, to allow for a better energy transfer from the laser to the matrix. The carbon fiber causes the laser to heat the material more quickly, as it absorbs the energy and conducts heat faster than the polymer can. This enables the molecules to better entangle and form a shape under the laser’s heat, without melting later.
After implementing the carbon fiber reinforcement, the researchers were able to successfully 3D print high-temperature polymer composite sample pieces in multiple configurations, such as test coupons and brackets, in what they believe, as the AFRL writes, to be “the highest temperature capable, polymer composite parts made by additive manufacturing to this day.”
“High temperature materials are notoriously hard and expensive to process, even using conventional manufacturing techniques. Since they typically wind up being used in military specific applications, there is not a large supplier base for these types of materials. This breakthrough will enable us to additively manufacture high temperature, composite parts in a cost-efficient manner. Moreover, high temperature polymer composite parts that are small and have complex features will be extremely beneficial and advantageous not only for the Air Force, but have the potential to be a game-changer throughout industry,” said Dr. Jeffery Baur, a principal materials engineer at AFRL.
“This is a high, value-added capability for the Air Force. We are excited about this breakthrough and look forward to seeing the impacts over the future.”
Looking to the future, the research team plans to demonstrate the ability of its novel material to 3D print larger parts, which could result in major cost saving for the USAF. According to preliminary test data, the material will be able to hold up well under very high temperatures, but in order to use it on Air Force platforms, more qualification and testing is required.
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