Strong effect of carrier gas species on particle velocity during cold spray processes

• Carrier gas species plays an important role in particle acceleration behavior.
• Helium as a carrier gas leads to higher increases in the particle velocity due to its lower molar mass.
• Higher helium carrier gas pressures results in higher increase in the particle velocity.

This study is a comprehensive investigation into the effect that the carrier gas species has on particle velocity during cold spray processes. Numerical simulations were the main method adopted to achieve this objective. A computational fluid dynamics (CFD) model was developed to predict the gas flow and particle velocity both inside and outside the nozzle. This model was experimentally validated and agreed well with the measured data. The carrier gas species was an important factor of the particle velocity. For an air propellant gas, using helium as the carrier gas increases the particle velocity due to the low average molar mass of the mixed propellant gas. Similarly, increasing the helium carrier gas pressure increases the molar fraction of helium in the mixed propellant gas and, thus, the particle velocity.