The Air Force Research Laboratory Polymer Discovery

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The Air Force Research Laboratory polymer discovery is making the rounds in the news. If you can’t take the heat, then stay out of the Air Force Research Laboratory because they’re cooking up some hot breakthroughs. Researchers at the lab have just created high temperature composites capable of being used in intensely heated environments. Future military applications for the polymer composites could be instrumental in bringing forth the next generation of military aviation devices, with the composites being used to advance areas such as the engine components of fighter jets.  

About The Air Force Research Laboratory (AFRL) 

The AFRL is headquartered at Wright-Patterson Air Force Base in Ohio. Over 80 years of critical research has derived from the lab and its predecessors, including much of today’s modern weapons and aircraft systems from the B-2 bomber to the F-22 fighter. Their mission is the discovery, development, and integration of technologies for air, space, and web war-fighting forces. 

AFRL Is Turning Up The Heat In The Polymer Additive Kitchen 

AFRL worked with researchers from the University of Louisville and NASA’s Glen Research center to accomplish the printing of reinforced polymer composite parts. These parts have a unique quality: they are the highest temperature-capable known of their kind to be on record. The team used additive technology to build the parts. The success of this material discovery could be a key element in a more cost-efficient generation of manufacturing for the Air Force and other aviation entities. 

Temperature- Resistant, Lightweight, And Strong Polymer Composites 

Dr. Hilmar, Koerner, a Polymer Matrix Composite Materials and Processing Research Team scientist and part of the AFRL’s discovery team, calls the finding “extremely impactful” and a “breakthrough” in composite material additive manufacturing. He theorizes practical applications for the 3D printed parts in turbine engines and engine exhaust hot areas due their ability to withstand extreme environmental conditions, including in excess of 300 degrees Celsius heat. 

Temperature isn’t the only thing that makes the polymer matrix composites so novel and attractive. They’re also a very lightweight design, which is highly beneficial when it comes to reducing an aircraft’s fuel consumption and increasing its flight range. Over the long-term, such benefits results in a lower operating cost for the aircrafts. And, this is true whether the aircraft is private or military. 

While lightweight, they’re extremely durable and strong, too. Polymer composites most often consist of some sort of fiber, such as glass, to reinforce the matrix. These fibers are embedded in an epoxy or similar material resin or matrix. The end result is stronger material. 

Laser sintering is a polymer additive manufacturing process used to yield a predesigned shape from polymer powder. A high temp laser runs across the bed of loose powder to create a computer generated shape one layer at a time. The laser continues to move over the powder, creating a new layer each time, until the completed 3D shape is finally fully formed. 

The team initially found that polymers printed exceptionally good, but didn’t fare so well in post-processing. When they removed the printed pieces from the polymer powder the shape didn’t hold. Koerner described it as melting into useless puddles. Molecules basically weren’t entangling well enough to form a solid shape. 

The team solved this ‘shaping’ issue by adding a carbon fiber filler to the resin material. This enabled a more efficient energy transfer from laser to matrix. Compared to polymer alone, the carbon filler material heated and absorbed the laser’s energy much faster. 

The result was the printing of high temperature polymer composites that are the most temperature withstanding on record produced by additive manufacturing. 

Additive Manufacturing Boosts Access And Efficiency And Reduces Costs 

Materials capable of withstanding high temperature environments are traditionally hard to process and very expensive. AFRL principal materials engineer Dr. Jeffery Baur spoke to the application benefits and advantages from the team’s successfully printing an easier to access alternative. He pointed out that these types of materials generally end up as applications specific to the military, not the private sector. So, there’s not a huge supplier portal to obtain them. Thanks to this revolutionary process, the military can now additively manufacture high temp composite parts in a cost-friendly, efficient, and expedient manner. 

Complex features, size, and weight of these composite parts are not only advantageous to the military, however. Baur says they could be an industry-wide game changer. 

This initial step of the research involved printing smaller test coupons and brackets. The next step is to print larger, more substantial parts. Eventually, the materials will need to be qualified as well. 

Baur points out that while this is a significant advancement in additive manufacturing with the potential for enormous benefits to the Air Force, the test data is still in the preliminary phase. Much more testing must be done before the Air Force or any other military entity can implement it as a cost-efficient alternative to meet their organization’s manufacturing needs.

In closing, this novel high temperature polymer composite 3-D printing has the potential to be a game changing addition to how parts are utilized and the overall costs and availability of applications. And, it’s not just an Air Force or military advancement. This technology could greatly impact the entire aerospace manufacturing industry if the research continues to be as promising as the initial printing of small parts has been thus far.

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