B. Jodoin, P. Richer, G. Bérubé, L. Ajdelsztajn, M. Yandouzi, University of Ottawa, Ottawa, ON, Canada; A. Erdi, University of Ottawa, OTTAWA, ON, Canada
Decades of work in thermal spray processes have shown that higher performance and lifetime coatings can be produced if the feedstock particles are accelerated to a high velocity and heated prior to impact in a non-reactive environment that allows the control of the chemical and microstructural composition of the particles. While High Velocity Oxygen-Fuel (HVOF) spraying and Low-Pressure Plasma Spraying (LPPS) techniques have been able to accelerate and heat adequately the feedstock particles prior to impact upon the substrate, use of the latter process is primarily limited to high value-added coatings due to the associated costs. Furthermore, although HVOF is one of the most used and successful thermal spray coating process it still lacks full control of the coating chemical and microstructural composition due to the particle heating in the combustion gases. Cold Gas Dynamic Spraying (CGDS) has recently been shown to address the chemical and microstructural composition control requirement for specific materials due to the inert gases used and low particle temperature involved in the process. Efforts to obtain a process having the benefits of both HVOF and CGDS have recently been made by reducing the operating temperature of HVOF through the addition of inert gas in the combustion chamber and shows promising results.
A new process, the Pulse-Cold Gas Dynamic Spraying process (P-CGDS) is introduced in the present work. It is envisioned that this new process would allow the particles to be accelerated to high impact velocities and intermediate temperatures, in a non-reacting gas. That way, the intermediate particles impact temperature would lead to lower required critical velocity compared to CGDS that could be easily reached while preserving the chemical and microstructural composition of the feedstock particles in the coating. The work presents a detailed description of the process, the experimental set-up developed at the University of Ottawa, and shows different coatings. Finally, conclusions are drawn from the results of the new method, as well as its perspective and future as a new class of Thermal Spray process.
Summary: A new process, the Pulse-Cold Gas Dynamic Spraying process (P-CGDS) is introduced in the present work. It is envisioned that this new process would allow the particles to be accelerated to high impact velocities and intermediate temperatures, in a non-reacting gas. That way, the intermediate particles impact temperature would lead to lower required critical velocity compared to CGDS that could be easily reached while preserving the chemical and microstructural composition of the feedstock particles in the coating.
