January 23, 2019 – Metal powder blasts from the end of the nozzle in a hurricane of nitrogen gas, colliding with the target at supersonic velocities. The powerful impact flattens the particles, welding them to the object and creating an essentially brand-new part with a lifespan measured in years instead of months or days.
The cold spray process is a dynamic technology that promises to both revolutionize much of the routine maintenance performed on naval assets, as well as significantly extend the life of older components, and the Naval Sea Systems Command (NAVSEA) 04X3’s Tactical Innovation Implementation Lab (TIIL) and Naval Undersea Warfare Center (NUWC) Division, Keyport are on the cutting edge, leading NAVSEA’s effort to field this innovation.
The TIIL led a Cold Spray Sprint Jan. 15 and 16 in order to advance fielding of cold spray into Navy maintenance in NUWC Division, Keyport’s Advanced Technology Innovation Center (ATIC). TIIL created sprints as fast-paced, action-based events focused on accelerating delivery of a specific technology or solution. The Cold Spray Sprint brought together representatives from many parts of the Navy, such as the four shipyards, the Ship Repair Facility in Yokosuka, the Trident Refit Facility, and Naval Air Systems Command (NAVAIR), as well as the U.S. Coast Guard, and several high-level civilian scientists.
“The sprint is not a meeting and not a working group,” said Janice Bryant, director of NAVSEA 04X3’s Tactical Innovation Implementation Lab. “It is work, and takes actions needed to transition a technology creating new capability to get ship’s done.”
Bryant was standing in Keyport’s vast Bldg. 73, which houses NUWC Division, Keyport’s ATIC, and was surrounded by a bustling crowd of engineers, active duty personnel, shipyard officials, and scientists. The cavernous structure echoed with multiple conversations as different parts of the Navy’s technological workforce addressed the multiple challenges of getting this cutting-edge process to the fleet.
Cold spray uses an inert gas, such as helium or nitrogen, to “fire” a powder at supersonic velocities onto a target structure in order to resurface that structure. The term “cold spray” refers to the fact this process involves relatively low temperatures during the bonding process, normally between 212 – 930 degrees Fahrenheit.
Traditional welding uses a far higher temperature range. Welding uses temperatures tend to start around 5,000 degrees Fahrenheit, and often go higher. Cold spray relies primarily on the kinetic energy imparted by the powder’s high velocity rather than high heat in order to bond it to the target structure. These lower temperatures mean the underlying metal being reworked is in no danger of distortion, nor of having its metallurgical properties unintentionally altered by heat.
The low temperatures also allow more than just metal to be used. Ceramics and composite material can be used to resurface and rebuild worn parts. New material combinations can be formed by the process that can’t be formed by other traditional alloying processes. The new coating is uniform and can be laid to any desired thickness. This essentially allows an old, worn part to become a framework upon which a new part is laid.
The TIIL team pulled the Navy together with this sprint in order begin the work of putting cold spray technology in the shipyards. Fielding such an innovative new system presents both logistical and engineering challenges that NUWC Division, Keyport, can begin to provide expertise to overcome.
“We’re taking the burden off the shipyards by being the project administers,” Bryant said. “We provide the methodology and systemic integration with lessons learned by the Army, Air Force and NAVAIR to accelerate fielding for NAVSEA.”
Cold spray technology will give NAVSEA a new level of cost-effective flexibility by allowing more repairs and maintenance internally.
“It’ll be organic; in house: our equipment, our people, our needs,” Bryant said. Cold spray technology can refurbish corroded parts in a relatively short amount of time to a high level of structural integrity, thus allowing those components a new lease on life and giving ships both in the yards and at sea access to a far greater range of less expensive and readily available parts and supplies.
“This process allows us to take something worn and reconfigure it to something new,” Bryant said.
Dr. Victor Champagne of the U.S. Army’s Cold Spray Center at the Army Research Laboratory (ARL) said the process was first described by Samuel Thurston in 1900 and patented by him in August 1902 under the title “Method of Impacting One Metal Upon Another.” However, Thurston was nearly 100 years ahead of his time and was unable to make the process work.
“He just didn’t have the hardware at the time,” said Champagne. It would be almost a century later before Russian scientist Dr. Anatoli Papyrin created a new, practical cold spray process and patented it. Papyrin eventually came to the U.S. to work with Penn State University and Sandia National Laboratories in the 1990s.
Champagne, standing next to a yellow robot that looked as if it would be at home in a Hollywood science fiction blockbuster, said his work with Papyrin allowed him to recognize the potential benefits of the technology. He assembled a cold spray team at the ARL and got the ball rolling within the United States. Even so, Champagne said it took nearly 20 years to reach the point where the technology is being fielded fleet-wide by the Navy. The ARL cold spray team had to figure out how to begin integrating the new technology into an existing world.
“This led to the establishing of applications, processes, and newer materials,” Champagne said. Each of these then had to be researched and developed in order to create a practical new system to employ. Champagne said the Air Force is slightly ahead of the Navy in the use of Cold Spray, but the technology and its applications are still only in their infancy.
Standing with a clipboard full of notes in hand, Brian Dougherty, a chemical engineer with NUWC Division, Keyport’s Rapid Prototyping and Fabrication Technology Division, said the forward leap of cold spray will be a significant factor in allowing engineers to shorten maintenance time and reduce costs by allowing components to be reused.
“Our main focus is restoring hardware and extending longevity,” Dougherty said. In today’s world, some ships and aircraft are expected to maintain operational capabilities for as long as nearly half a century (perhaps longer). Dougherty said cold spray is a practical innovation that will enable those systems to be kept running at a fraction of the cost and man-hours needed today.
Alex Frank, a mechanical engineer who also works in the Rapid Prototyping and Fabrication Technology Division, agreed. Standing next to a self-contained, mobile cold spray unit that is expected to end up pierside in the near future, Frank said cold spray was good for more than just replacing traditional welding in many jobs.
“This can replace brush plating and epoxy repairs,” Frank said. Both brush plating and epoxy repair involve hazardous chemicals and require hours, if not days, to complete.
Eventually a mobile cold spray unit that employs an articulated robot could possibly be installed directly into a space on a ship or submarine to complete a repair or conduct required maintenance in a fraction of the time and provide a more robust repair solution over existing outdated technologies.
The goal is to meet the national defense strategic goal of a 355-ship Navy while reducing costs, labor, and even the environmental impact of maintenance and repair processes. Cold spray technology promises to be a critical tool in this effort by shortening maintenance and repair times, and allowing worn components to be made new and return to service in the fleet.
“We’ve hit the limits of efficiency on older processes,” said Dougherty. Cold spray will allow the Navy to sprint into the future, extending the useful life of older components at a fraction of the time and cost, thereby helping ensuring the success of NAVSEA’s mission to ensure freedom on the high seas.