Solution and Suspension Plasma Spraying of Nanostructure Coatings

Effect of Processing Parameters and Powder Size on Microstructures and Mechanical Properties of Y₂O₃ Coatings Fabricated by Suspension Plasma Spray

“…First of all, the particle size in SPS is smaller than the mean free path of the plasma gases, a few micrometers at a plasma temperature of around 10000 K. 23) So, the interaction between particles and gases is reduced, and is less likely to transfer momentum to the particles; this is known as the Knudsen effect. 24,25) Therefore, not only is the particle velocity in SPS usually lower than that in conventional APS, but also the velocity decreases easily with increasing stand-off distance due to the particles' lower inertia. Then, velocity and the related kinetic energy of the molten particles in SPS are not as high as those in conventional APS, resulting in less densification driving force coming from the impact of the molten particles on the substrate.…”

“…Then, velocity and the related kinetic energy of the molten particles in SPS are not as high as those in conventional APS, resulting in less densification driving force coming from the impact of the molten particles on the substrate. Second, the smaller particle size and lower velocity result in lower values of the Stokes number S t , 24,25) , where ρ p , d p, and v p are the density, diameter, and velocity of the molten particles, and μ g and l BL are the viscosity of the gas and the thickness of the boundary flow layer along the substrate surface, respectively. If S t is lower than 1, this means that the particles cannot easily penetrate the boundary flow layer, which is the compressed zone with high pressure just over the substrate surface.…”

Contributions to heat and mass transfer between a plasma jet and droplets in suspension plasma spraying

“…Introducing nanoparticles in a plasma core requires putting them in a solution or suspension due to their low inertia [3]. So, from this starting point, understanding suspension plasma spraying implies different stages of analysis: -The first step involves hydrodynamic interactions between the charged liquid with the plasma jet leading to the breakup of the liquid suspension jet into droplets.…”

Feedstock suspensions and solutions

“…(2) Use of a carrier liquid instead of a carrier gas (suspension plasma spraying, SPS) (Pawlowski, 2009;Fauchais et al, 2008;Fauchais and Vardelle, 2012).…”