Cold spray extends the life of critical equipment—at supersonic speed
- janakuthe8
- 4 days ago
- 4 min read
Cold spray is emerging as a powerful repair technology, helping industries extend the life of ageing assets while reshaping supply chains. In December, Professor Tim Eden from Pennsylvania State University visited Australia to deliver a two-day course in Melbourne on the unique challenges of performing cold spray repairs outside a traditional laboratory environment. In this interview, he explains how the technology works—and where it delivers the most value.
Cold spray can be used for repair and restoration as well as near-net-shape additive manufacturing. In sustainment applications, it enables fast, localised repairs that significantly reduce cost and downtime, while extending the service life of high-value components that would otherwise require replacement.
While the technology’s origins can be traced to scientific discoveries of the late 19th century, its modern form emerged from Russian research in the 1980s and was subsequently advanced through industrial R&D—particularly in the United States—during the 1990s. By the early 2000s, cold spray had transitioned into industrial use. Continued improvements in system design, materials combinations and process understanding have since driven widespread adoption across a growing range of applications.
Cold spray is a solid-state process in which solid metal, or a mixture of metal–ceramic particles are introduced in a heated, compressed gas stream and accelerated through a converging–diverging nozzle to supersonic velocities. On impact, the particles plastically deform and bond to the substrate or to previously deposited material, forming a dense, well-bonded coating.
A pivotal breakthrough involved understanding “two-phase” flow—solid particles carried within a gas stream—and the conditions required to achieve bonding. At lower velocities, particle impact results in sandblasting; at sufficiently high speeds, particles bond to the surface and to each other. Throughout the process, both the particles and the substrate remain in the solid state, with no melting, no chemical dissolution and minimal thermal input.
Professor Tim Eden, Head of the Advanced Manufacturing and Materials Engineering Division at The Pennsylvania State University’s Applied Research Laboratory, first encountered cold spray research at Penn State in 1996 and began his own work on the technology the following year. He also holds appointments in Engineering Science and Mechanics, Additive Manufacturing and Design, and the Inter College Graduate Degree Programs at Penn State.
From fundamentals to field deployment
“The reason my boss wanted me to help develop cold spray technology was that I had the compressible flow background to understand the gas dynamics, mechanical design experience, and modeling expertise,” Eden said. “All of that previous work really set me up for cold spray.”
His first major project focused on anti-corrosion coatings for military vehicle armour—an early demonstration of the technology’s potential for repair and life extension.
For repair applications in particular, Eden sees strong advantages.
“It’s especially useful in industries dealing with corrosion and wear—oil and gas, maritime, land vehicles and aerospace,” he said. “It can dramatically reduce repair times and save parts that would otherwise be scrapped.”
There are several examples where cold spray has been used to repair high value components that could not be repaired using other technologies, met the repair schedule and saved millions of dollars.
Looking ahead, he expects the next decade to bring wider adoption and greater capability, including structural—not just cosmetic—repairs, along with a broader range of powders suited to different materials and environments.
Today, the technology has matured well beyond the lab and is it potential for the manufacture of near-netshape is being exploited.
Advantages—and trade-offs
As with all additive manufacturing technologies, cold spray has strengths and limitations. Many of its advantages stem directly from its solid-state nature.
“Because the particles don’t melt, you don’t get dissolution of the substrate or deposited material,” Eden explained. “The chemical composition of the substrate and powder don’t change. This also reduces the amount of distortion during the deposition process."
By contrast, melt-based processes can alter material chemistry at the interface, particularly when joining dissimilar materials.
Cold spray also offers significantly higher deposition rates than processes such as selective laser melting or electron beam melting, allowing repairs to be completed more quickly. It does not require inert gases like argon to prevent oxidation, simplifying deployment in non-laboratory environments.
In additive manufacturing, parts produced via cold spray typically require more postprocessing to achieve final mechanical properties and machining to achieve the required dimensions.
Repairing in the real world
Eden recently shared his expertise through Cold Spray for In-Field Repair: A Practical Operator’s Course, delivered as part of the Symposium on Emerging Materials and Innovations in Thermal Spray (SEMI 25).
The hands-on, two-day course at Swinburne University of Technology attracted 14 technicians and engineers and focused squarely on real-world applications. Participants worked with portable cold spray systems from SST Centreline and Additive Manufacturing CRC partner Titomic.
In-field repair is one of the fastest-growing areas for cold spray, with applications ranging from oil and gas infrastructure to ship hulls and marine structures.
For organisations considering cold spray as a repair solution, Eden advises starting with the fundamentals.
“You need to think about what materials you’re repairing, how often repairs are required, and then select the right system,” he said. “There are high-, medium- and low-pressure systems.”
Low- and medium-pressure systems are easier and less expensive to deploy, requiring less supporting infrastructure. High-pressure systems, while more complex and costly, are necessary for harder, higher-temperature materials.
Ultimately, Eden said, the decision comes down to a balance of application requirements, material performance—and budget.
