Inner diameter High-Velocity Air Fuel (ID-HVAF) spraying of Copper, compared to Cold spray

As a supersonic solid-state deposition process, Cold Spray (CS) has a unique role among other thermal spray techniques as it uses compressed and heated gas to accelerate particles to a critical velocity, but the high cost of CS has become a disadvantage of this process. In recent thermal spray developments, High-Velocity Air Fuel (HVAF) has taken a specific place in terms of providing denser and stronger coatings than CS, but also coatings with less oxidation than High-Velocity Oxy-Fuel (HVOF). In contrast to these techniques, HVAF uses a mixture of fuel and air, instead of pure oxygen as in HVOF, to accelerate particles. Therefore, HVAF appears as an inexpensive and environmentally friendly process for the deposition of a wide variety of materials. The aim of this research is to produce fully dense copper coatings with limited oxidation using an inner diameter (ID) HVAF system and to compare the microstructure with CS copper coatings. Coating microstructures, oxygen content, surface roughness, and microhardness are studied using different characterization methods such as Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). Through this paper, the influence of both spray processes, cold spray, and ID-HVAF, on the deposition of copper coatings is discussed.