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High Temperature Material Processes: An International Quarterly of High-Technology Plasma Processes
SJR: 0.137 SNIP: 0.341 CiteScore™: 0.43

ISSN Imprimir: 1093-3611
ISSN On-line: 1940-4360

High Temperature Material Processes: An International Quarterly of High-Technology Plasma Processes

DOI: 10.1615/HighTempMatProc.v7.i3.10
pages 277-298

IN-FLIGHT OXIDATION AND EVAPORATION OF PLASMA-SPRAYED IRON PARTICLES

Hanwei Zhang
Columbia University, Department of Earth and Environmental Engineering, New York, NY 10027, USA
Armelle Vardelle
ENSIL, ESTER Technopole, 87068 Limoges - France
Nickolas J. Themelis
Columbia University, Department of Earth and Environmental Engineering, New York, NY 10027, USA

RESUMO

Metal particles injected in a plasma jet flowing through air may be subjected to evaporation and reaction with entrained oxygen. These phenomena are undesirable from the viewpoints of quality of coating, powder utilization, and fume formation. This paper is concerned with the plasma-spraying of iron powders and presents the results of four sequential models that simulated, a) temperature/velocity/concentration profiles and particle trajectories in the jet flow, b) heat transfer between plasma gas and particles, c) interaction between iron evaporation and oxidation phenomena, and d) oxidation rate of liquid iron droplets along particle trajectories The results showed that oxidation may be enhanced by induced flow within the particle that sweeps away the outer layer of iron oxide and exposes new metal surface. Also, the presence of oxygen in the enveloping atmosphere enhances metal evaporation by decreasing the thickness of the boundary layer around the particle. The model projections are in fair agreement with experimental observations of plasma-sprayed iron particles and fume formation.