US EPA

4965564 

Journal Article 

Effect of Helmholtz Oscillation on Auto-shroud for APS Tungsten Carbide Coating 

Jin, Y; Choi, S; Yang, SJae; Park, CRae; Kim, GonHo 

2013 

1 

Journal of Thermal Spray Technology
ISSN: 1059-9630
EISSN: 1544-1016 

22 

5 

756-763 

10.1007/s11666-013-9910-2 

WOS:000319297400021 

The atmospheric-pressure plasma spray (APS) of tungsten coating was performed using tungsten carbide (WC) powder by means of DC plasma torch equipped with a stepped anode nozzle as a potential method of W coating on graphite plasma-facing component of fusion reactors. This nozzle configuration allows Helmholtz oscillation mode dominating in APS arc fluctuation, and the variation of auto-shroud effect with Helmholtz oscillation characteristics can be investigated. Tungsten coating made from WC powder has lower porosity and higher tungsten purity than that made from pure tungsten powder. The porosity and chemical composition of coatings were investigated by mercury intrusion porosimetry and x-ray photoelectron spectroscopy, respectively. The purity of tungsten coating layer is increased with the increasing frequency of Helmholtz oscillation and the increasing arc current. The modulation of Helmholtz oscillation frequency and magnitude may enhance the decarburization of WC to deposit tungsten coating without W-C and W-O bond from WC powder. 

atmospheric-pressure plasma spray (APS); auto-shroud effect; Helmholtz oscillation; in-flight oxidation; plasma facing component (PFC); tungsten carbide (WC)