Cold Spray Processing and Repair Design for Helicopter Components

The cold spray process is currently being utilized to repair metallic production and field-returned helicopter components. The process is a low, solid-state temperature deposition technology in which fine metallic powder particles are injected into a supersonic velocity gas stream to produce a dense deposit by impact onto the substrate surface. The non-melted metallic particles form cold welded bonds with metal substrates, and additional spray passes can achieve deposition layers up to a few inches in thickness. As a result, the cold spray process can be used to repair and rebuild features on field returned parts with damages such as corrosion or wear and on production parts with non-compliance to the drawings such as casting anomalies or machining issues. The successful repair of components using the cold spray process can require various levels of engineering design, processing expertise and machining knowledge. The degree of evaluation is generally based on the complexity of the repair and/or the intended end use of the component. This paper will focus on developing complex cold spray repairs that require high bond strength and minimum porosity levels in the deposit which are typically achieved using a high pressure cold spray system.