Effect of shrouded CO{sub 2} gas atomization on coating properties in wire arc spray
- Univ. of Minnesota, Minneapolis, MN (United States)
Porosity and oxide content are important factors influencing coating quality. Interaction of the sprayed particles with the surrounding air during non-reactive wire-arc spraying has a negative effect on the quality of the coating and limits the possibilities of obtaining coatings of chemically active materials. One of the methods to protect a non-reactive gas (CO{sub 2}) from mixing with air is the application of special nozzles (shrouds). In this study, a shroud nozzle with secondary injection of shrouding gas has been developed for spraying with CO{sub 2} gas to improve coating quality. Wire arc spraying of stainless steel on aluminum substrates using CO{sub 2} gas atomization has been investigated with the objective of establishing correlations between voltage fluctuations, droplet sizes and coating properties such as porosity and oxide content. Compared to the oxide content (21%) and porosity (16%) of air sprayed coatings, further reduction of oxide content (6%) and porosity (4%) is achieved by using a shrouded nozzle with secondary gas injection. A shrouded nozzle can prevent atomizing gas from mixing with surrounding air, which results in less oxide content and less chromium loss in the coating. Also secondary gas injection contributes to better atomization of the droplets, which leads to less porosity of the coating.
- OSTI ID:
- 377734
- Report Number(s):
- CONF-9509182--; ISBN 0-87170-541-9
- Country of Publication:
- United States
- Language:
- English
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