Effective Injection of Ceramics Nanoparticle Pastes into Plasma Spray for Speedy Layer Formation

Abstract

Thermal nanoparticle spraying was developed to create fine ceramics layers on free surfaces. Resin slurry containing ceramics nanoparticles were atomized by a compressed air jet in a chamber, and the resulting micro mists of composited droplets were effectively injected from a tubular nozzle into the plasma flare. Alumina particles with average diameters of 200 nm were dispersed into the acrylic liquid resin at 40% volume ratio. The microsized mist droplets with average diameters of 20 μm were first formed using the compressed air jet under pressure of 2 atm, and then introduced into the arc plasma with an argon gas spray of 50 slpm in flow rate. The alumina layer of 300 μm thickness was formed successfully on the SUS-304 substrate of 50×50×5 mm in size, which was placed at a distance of 100 mm from the plasma gun, and a higher speed coating at the deposition rate of 50-100 μm/s was achieved. Crystal phases of the coated layer were analyzed by X-ray diffraction. The cross sectional microstructures were observed with optical and scanning electron microscopy. Porosities of the coated layers were estimated through dielectric constant measurements using terahertz wave spectroscopy.

Stereolithographic additive manufacturing of acoustic devices with spatially modulated cavities

“…Thermal nanoparticle spraying can rapidly create fine ceramic layers on practical components with curved surfaces. 31,32 Resin pastes with ceramic or metal particles were spattered by using compressed air. Blown mists of microdroplets were continuously introduced to gas flames.…”

Process Visualization of Thermal Nanoparticle Spraying Using Micro Composite Fragments

“…Novel plasma spraying processes using nanoparticle suspensions or pastes have been developed to solve the above-mentioned technical difficulties in fine particle transfers and introductions [8,9]. In the suspension plasma spraying process, nanoparticles are dispersed in aqueous or organic solvents to be injected into plasma or gas flames.…”

Microstructural Control of Thermal Nanoparticle Spraying Using Micro Composite Fragments

“…Novel plasma spraying processes have implemented the use of nanoparticle suspensions, or pastes, to solve the abovementioned technical difficulties 8), 9) . In nanoparticle suspension plasma spraying processes, the nanoparticles are first dispersed in aqueous or organic solvents before being injected into the plasma or gas flame.…”