High-Performance, No-Helium Cold Spray for Structural Repair Applications

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Sustainment

OBJECTIVE: Develop a high-performance cold spray system which can deposit structural quality repair material for aluminum and titanium without using helium as the carrier gas.

DESCRIPTION: High-performance cold spray systems require helium carrier gas to achieve required particle deposition velocity and high-performance deposits of aluminum, titanium, and high-strength steel that have lower than 1% porosity [Ref 1]. Helium is a limited resource, expensive and highly sensitive to changes in market supplies, some of which come from Russia and other foreign countries. The cost of helium is currently about 100 times more than nitrogen, which is used in cold spray systems, but produces material with up to 10% porosity [Ref 2]. As such, the cost of helium for most repairs under consideration is a large percentage of the overall repair cost and reduces the cost-benefit for many applications. In addition, access to helium can be restricted, impacting testing and repair schedules.

A cold spray system that does not use helium and can deposit aluminum, titanium, and high-strength steel with the properties of these materials deposited using today’s high-pressure, helium-based systems is needed.

PHASE I: Develop a concept for a cold spray system that can deposit aluminum, titanium, and high-strength steel at lower than 1% porosity without using helium. Demonstrate feasibility of meeting pressure, operating temperature, transfer efficiency, interfacial adhesion, tensile and elastic modulus, static and fatigue strength, elongation, and hardness properties against the threshold and goal targets provided by the Naval Air Warfare Center Aircraft Division (NAWCAD). Model powder deposition parameters. Prepare a report to ONR and NAWCAD on design(s) and modeling and prepare a Phase II testing plan.

PHASE II: Construct a prototype non-helium cold spray system and assess the material properties of the deposition of aluminum 7050-T7451, Ti6-4, and AerMet 100 powders. Assess the properties of repaired 7050-T7451, Ti6-4 and AerMet 100 substrates using cold spray-applied powders of the same alloys. Provide a report that documents the design of the prototype system, results of system performance and results of material testing for the three alloys. Provide a Phase III plan to ONR and NAWCAD for prototype evaluation. Provide a prototype non-helium cold spray system to NAWCAD for evaluation.

PHASE III DUAL USE APPLICATIONS: Assemble a full non-helium cold spray system and demonstrate output meeting key deposition and material parameters. Deliver a full non-helium cold spray system to NAWCAD and report containing designs and test data to ONR and NAWCAD. Dual use applications may include light metal repairs in the aviation industry.

REFERENCES:
1. Joint Technology Exchange Group. “JTEG Technology Forum: Cold Spray Repair.” https://jteg.ncms.org/jteg-technology-forum-cold-spray-repair/
2. Widener, Christian; Ozdemir, Ozan; and Carter, Michael. “Structural repair using cold spray technology for enhanced sustainability of high value assets.” Procedia Manufacturing, Volume 21, 2018, pp. 361-368. https://reader.elsevier.com/reader/sd/pii/S2351978918301719?token=89EDB6C0287F5C6C578F915E2316AC0A49F5458D3B52AB399259F1C0B17E0E0A931F7CD959A0B985B002B2CCACFEB36B&originRegion=us-east-1&originCreation=20221221152929; 10.1016/j.promfg.2018.02.132
3. Champagne Jr., Victor and Helfritch, Dennis. “Critical Assessment 11: Structural repairs by cold spray.” Materials Science and Technology, Volume 31, 2015, pp. 627-634. 10.1179/1743284714Y.0000000723
4. Ozdemir, O.C.; Widener, C.A.; Helfritch, D. and Delfanian, F. “Estimating the Effect of Helium and Nitrogen Mixing on Deposition Efficiency in Cold Spray.” Journal of Thermal Spray Technology 660, Volume 25, Issue 4, April 2016, pp. 660-671. DOI: 10.1007/s11666-016-0394-8

KEYWORDS: Cold spray, aerospace alloys, non-helium, repair, maintainability, metals