Influence of Plasma Torch Power on the Plasma Jet Properties and Microstructure of Alumina Coatings

In this study, alumina coatings were formed using atmospheric plasma spraying, increasing the torch power from 29.4 to 45.1 kW. The surface morphology of the coatings was determined using scanning electron microscopy; the elemental composition was examined using energy-dispersive X-ray spectroscopy...

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Bibliographic Details
Published in:Coatings (Basel) 2022-07, Vol.12 (7), p.934
Main Authors: Šuopys, Airingas, Grigaitienė, Viktorija, Marcinauskas, Liutauras, Kėželis, Romualdas, Uscila, Rolandas, Aikas, Mindaugas
Format: Article
Language:English
Subjects:
Alumina
Aluminum oxide
Cameras
Ceramic glazes
Chemical composition
Coatings
High speed cameras
Morphology
Phase composition
Plasma
Plasma jets
Plasma spraying
Process controls
Profilometers
Protective coatings
Raw materials
Sprayed coatings
Surface roughness
Thermocouples
Transitional aluminas
Velocity
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Summary:In this study, alumina coatings were formed using atmospheric plasma spraying, increasing the torch power from 29.4 to 45.1 kW. The surface morphology of the coatings was determined using scanning electron microscopy; the elemental composition was examined using energy-dispersive X-ray spectroscopy (EDS); phase composition was investigated using X-ray diffraction; and surface roughness was determined using a profilometer. The steel surface temperature was measured using a type-K thermocouple, and the plasma jet temperature, at a distance of 70 mm, using a type-B thermocouple. Alumina particle velocity was calculated by analyzing high-speed camera footage using ImageJ software. The results indicate that plasma jet temperature, speed, and in-flight particle velocity increased with plasma torch power. Furthermore, the amount of γ-Al2O3 phase in the coating increased, and the α-Al2O3 decreased with increasing plasma power. The surface roughness (Rq) of the Al2O3 coatings decreased from 7.13 to 5.54 μm, with an increase in torch power. The EDS measurements indicate that the increase in torch power did not affect the elemental composition of as-sprayed coatings. The results provide a wider understanding of an atmospheric plasma spray technique, optimizing and controlling the parameters using air as a primary gas.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings12070934