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High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes)

An International Journal

ISSN for PRINT: 1093-3611

Institutional price:	$604.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2003, Volume7

145 pages

DOI: 10.1615/HighTempMatProc.v7.i3

Issue price - $144.00

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
University of Limoges, Laboratoire Sciences des Procédés Céramiques et de Traitements de Surface, ENSIL,16 rue d'Atlantis, 87068 LIMOGES Cedex, France

Nickolas J. Themelis
Columbia University, Department of Earth and Environmental Engineering, New York, NY 10027, USA

ABSTRACT

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.