Cold Spray for Aerospace, Defense, and Energy Applications

Additive manufacturing, alongside established processes like powder bed fusion and cold gas spraying (also known as cold spraying), has gained great momentum in the last several years and is becoming increasingly important. This approach is opening up new opportunities where conventional technologies are reaching their limits: for large-sized components, complex material combinations, or refractory materials. The manufacturing process and the quality of the powders are the crucial factors for success — and this forms the basis for the collaboration between Impact Innovations and TANIOBIS.

Impact Innovations is a global provider of developing industrial cold gas systems and processes. In addition to its research and development services, the German corporation manufactures industrial cold gas spraying systems for users in a wide variety of sectors around the world. Its goal is to establish cold spray as a viable technology for surface coating and additive manufacturing in the future. The company was founded in Rattenkirchen in 2010 and has since supplied clients in the aerospace, defense, electronics, automotive, energy, and household goods sectors.

Manufacturing Without Melting Process or Oxidation

In the cold spray process, a carrier gas accelerates metal particles at supersonic speed and projects them on to a surface in a solid state. The kinetic energy ensures the metallurgical bonding without the need to melt the material in advance. This simple principle is making a huge impact.

First, typical disadvantages found in melting-based processes do not apply because no oxides are formed in the melting procedure, no structural changes take place, and no thermally-contingent tensions, which can cause cracks, occur. Second, it is possible to manufacture robust components that also include high deposition rates and low porosity.

Cold spray also allows a combination of very different materials. Gradient layers or multimaterial components are just as feasible as the specific coating of individual areas. Scalability up to large-sized structures makes the process particularly interesting for sectors where classic powder bed processes are reaching their limits, for instance, with rocket or jet engine components.

When Materials and Processes Harmonize

Powders must have precisely defined properties to enable cold spray to exploit its full potential. The process can powerfully demonstrate its benefits, particularly with metals such as tantalum and niobium, which have high melting points — Fig. 1. Both are so-called refractory metals, whose melting point exceeds 3000°C. They are corrosion resistant and temperature resistant and are, therefore, hard to process using conventional procedures. The cold spray system avoids these restrictions because the melting process is unnecessary. As a result, it is even possible to process challenging materials reliably and without a protective chamber.

Material efficiency is another benefit. As almost all the powder is bonded in the component, the buy-to-fly ratio, which is the ratio of starting material to the final product, is almost one. This significantly reduces the material costs, particularly with high-cost alloys like C-103. The process also opens up new design opportunities and options — Fig. 2. Wall thicknesses starting at 0.5 mm are feasible, so that fine, light structures can be formed, which are still extremely robust.

Combining cold spray with tantalum and niobium alloys, therefore, offers a solution that overcomes material restrictions and enables components that are both able to withstand mechanical stress and can be produced cost effectively.

Powder Expertise for the Toughest Demands

Impact Innovations often works with alloys such as C-103, a niobium-based alloy with tantalum, hafnium, and titanium, as part of research and development projects for the aerospace sector, for instance.

This extremely expensive alloy is viewed as the preferred material for jet engine components in the aerospace sector. “C-103, however, is subject to strict export controls,” explained Jan Kodas, an R&D engineer at Impact Innovations. “Thanks to TANIOBIS’s experience as a German and European supplier of tantalum or niobium and the corresponding alloys, we’ve still been able to reliably use the material and deploy the process in a stable manner.”

TANIOBIS has over 60 years of experience in processing tantalum and niobium materials. The corporation has a reputation as a reliable partner for individual powder solutions, ranging from implants in medical engineering to components for the chemical industry and high-temperature applications for the aerospace sector.

Geographical proximity and reliable supplies, however, are not the only benefits of the collaboration for Impact Innovations; the company can also directly realize specific requests. TANIOBIS adapts the particle size distribution to the cold gas spraying requirements; by combining cold spray with its powders, new opportunities are opening up to manufacture components with a high degree of reproducibility and defined properties.

Material Utilization of More Than 90%

Impact Innovations has displayed the efficiency of its EvoCSII system in tests with a demonstrator. Deposition rates of more than 90% have been achieved when using the TANIOBIS powders, an unusually high figure compared to other additive processes. The results reveal that C-103 can be processed efficiently to reproduce components using the technology.

Prospects for Future Industries

Combining the Impact EvoCSII system technology with the TANIOBIS powders shows how it is possible to manufacture large-sized structures with complex geometries without the disadvantages of conventional forming and welding processes. Users in the defense and energy industries are benefiting from the possibility of coating components with different materials or completely forming them. The process can also display its strengths in repairing large components that would be disproportionately expensive to replace.

Cold spray is not only an addition to established additive technologies for Impact Innovations and TANIOBIS, but it’s also a genuine alternative in many cases. The partnership with Impact Innovations illustrates how technology and material expertise can go hand in hand. Together, the companies are setting new standards for industrial manufacturing in the field of high-temperature and special applications ranging from aerospace to the energy industries.

This article was supplied by TANIOBIS GmbH (taniobis.com), Goslar, Germany.