Manufacturing nanostructured YSZ coatings by suspension plasma spraying (SPS): effect of injection parameters

Abstract

The suspension plasma spraying process is investigated by using shadow imaging techniques to appreciate the different trajectories of the liquid jet interacting with a DC highenergy plasma flow. Then, the modelling of different liquid injections (isolated droplet, train of droplets and continuous jet) helps to determine which injection type must be preferred. From that, coating depositions have been carried out with yttria zirconia suspension. Trajectory deviations at impact have been measured depending on the injection pressure and injection location. Coatings have been realized under the same operating investigations and their microstructures and mechanical properties have been characterized.

Comparison between Suspension Plasma Sprayed and High Velocity Suspension Flame Sprayed bioactive coatings

“…This may be due to non-uniformities in the fragmentation process of the injected suspension stream. The radial injection method, which results in quite different liquid drop sizes and trajectories [41,42], and the typical voltage fluctuations of plasma torches operated with Ar-H 2 gas mixtures, which cause unstable plasma flow conditions [43], could be the main reasons for this non-uniformity.…”

“…Due to the radial injection scheme, and to the periodic fluctuations in plasma energy, liquid drops follow very different trajectories in the gas stream [41][42][43]. The particles therefore reach the substrate with a wide range of temperatures and velocities.…”

Adhesion of Ceramic Coating on Thin and Smooth Metal Substrate: A Novel Approach with a Nanostructured Ceramic Interlayer

“…The plasma spray conditions and suspension injection conditions were chosen, thanks to a design of experiments (Ref 5,6), based on mechanical properties of the coating: hardness, Young modulus determined by nanoindentation test. The used combination of plasma spray conditions and suspension injection conditions made it possible to get a break-up of the liquid suspension in the catastrophic regime in the plasma core.…”

A study of liquid droplet disintegration for the development of nanostructured coatings

“…13 Liquid feedstock alumina has also been deposited by plasma spraying with controlled coating density and with high levels of thermodynamically stable corundum (a-Al 2 O 3 ), which is necessary for good wear resistance and electrical insulation. 23, exhibiting stripping and catastrophic breakup of the droplets. SPTS of TiO 2 using flame spray have successfully created nanostructured coatings, consisting of 80% 18 and 95% 19 anatase phase.…”

“…Detailed images of the initial disintegration of liquid feedstock injection are provided in Ref. 23, exhibiting stripping and catastrophic breakup of the droplets. Depending on the size of the liquid droplets, the intensity of the flow and the liquid feedstock properties, the droplets may precipitate their solid mass along one of many process routes, as depicted in Figure 1.…”