Composite Heat Release technology for firearm barrel manufacturing

Rifles must be extremely accurate; hitting a target is all that matters once a rifle is fired whether it’s at a shooting competition, hunting in the woods, or on the battlefield. That requires a stiff rifle barrel and the heat from firing can slow down how quickly a shooter can pull the trigger again or even warp the barrel. Composite wrapped barrels have been introduced to the market to help reduce the effects of heat on metal barrels.

Avient Corp., a materials provider, knew however that more could be done to reduce the heat effects. After speaking with clients in the air rifle industry, Yves Cordeau, technology manager at Avient, and his team have developed Composite Heat Release, a multi-layer carbon fiber and ceramic composite technology.

Composite Heat Release uses the original steel bore of the barrel that’s been turned down. A ceramic hybrid material is placed between the steel and a custom-made carbon fiber tube.

“Avient doesn’t want to create a ‘me too’ product, we want to create something that’s going to be the next generation of improvements,” Cordeau says. “So, we took a step back, took a look at understanding what the challenges are with composite wrapped barrels, and the number one thing that kept coming up was heat retention.”

Thermal inertia vs. thermal conductivity

Cordeau says they’ve focused on thermal inertia instead of thermal conductivity, the industry standard, when developing a technology to help cool materials faster while allowing them to remain stiff and lightweight. Thermal conductivity measures are based on mass, so high-density materials such as steel have the advantage when it comes to how well they absorb energy in the form of heat. Thermal inertia is measured based on volume and how quickly a material returns to ambient temperature after heating, so low-density materials such as ceramics and polymers have the advantage.

“A low thermal inertia system, once it has heat inside from energy, will start to release that energy right away, that’s how it’s designed,” Cordeau says. “By using thermal inertia in the designs of our materials, by approaching things such as ceramics and polymers, which are not traditionally high thermal conductivity materials, we’re seeing practical results where things are cooling very fast. Thermal inertia is really the driving force behind that.”

Cordeau knows sometimes there’s concern or hesitation about using newly developed technology compared to a traditional method, especially when it comes to coefficient of thermal expansion (CTE). Despite using dissimilar materials, Composite Heat Release doesn’t crack, disconnect, or disbond in high-heat applications. The dissimilar materials actually work together as carbon fiber has an extremely low CTE so it shrinks when heated, steel likes to expand when heated, and ceramic has an extremely high compression strength. Composite Heat Release expands steel into high compression strength ceramic held in place by a high strength carbon fiber.

Expanded use of Composite Heat Release

Right now, Composite Heat Release is only being used on rifle barrels because that’s where the technology is most effective. The Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) mandates rifle barrels must be able to handle a maximum pressure of more than 60,000psi, so barrels must be moderately thick to withstand that pressure. Shotguns however have a SAAMI max pressure of approximately 12,000psi so the barrels don’t need to be nearly as thick as a rifle. On fixed barrel pistols, there’s not enough length on the barrel for Composite Heat Release’s benefits to be felt, while a floating barrel pistol currently causes too much abrasion for the technology to be effective. Cordeau is investigating other types of systems, more advanced rifle systems, muzzle attachments, and “things that see a lot of heat.”

The expansion of Composite Heat Release is also being investigated on the military front as Cordeau has seen interest in incorporating the technology into thermal management systems inside vehicles such as tanks. As the military moves toward more battery-powered vehicles, heat mitigation will be at a premium to help combat the excess heat produced by the batteries. Cordeau has also received inquiries about incorporating the technology into weapons systems requiring higher temperature barrels.

But for now, Avient will continue their focus on improving rifle barrels. Cordeau’s team partners with existing original equipment manufacturers (OEMs) with their own barreling and rifling technologies but not the composite material expertise. Composite Heat Release is added to the OEMs’ barrels and still allows the OEMs’ name to be on the product.

“Avient doesn’t make barrels, we’re making barrels better for our customers,” Cordeau says. “Customers who are focused on extremely lightweight, very stiff barrels, may want to take a lot of their steel down and put in the most ceramic possible. If they want it to cool very rapidly? The more ceramic, the faster it’ll cool. If our customers are more interested in aesthetics, we can focus on having a stiffer barrel with more steel. It’s their choice at the end of the day, which makes it a completely customizable solution.”

Avient is in the middle of commercializing Composite Heat Release technology as they’re at different development stages with multiple OEMs and barrel manufacturers but is optimistic about seeing the technology on rifle barrels in gun stores this year.

Avient Corp.
https://www.avient.com

About the author: Jake Kauffman is managing editor with GIE Media’s Manufacturing Group. He can be reached at JKauffman@gie.net.