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Proceedings Paper

Diagnostics of thermal spray processes by in-flight measurement of particle size and shape with innovative particle-shape-imaging (PSI) technique
Author(s): Tilo Streibl; Thomas Duda; Klaus D. Landes
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Paper Abstract

In the simplest terms possible, thermal spraying coating involves heating a material, in powder or wire form, to a molten or semi-molten state. The material is propelled using a heat source, e.g. a very high temperature plasma flame to deposit it, creating a surface structure on a given substrate. The process is very complex because it depends on numerous parameters influencing each other. A necessary condition to improve process efficiency and quality of produced coatings is the determination of in-flight particle properties. The innovative Particle-Shape-Imaging (PSI) technique offers a new potential in particle diagnostics. It is intended for the analysis of size and shape of single particles within the plasma jet. The method is based on telemicroscopic imaging of the particle shades. A cw-laser beam is split into two beams of equal intensities, which are superimposed in the focal plane of a long-distance-microscope. The detection system consists of a CCD camera with a Micro- Channel-Plate intensifier allowing exposure times of a few nanoseconds. When a particle passes the measuring volume, the laser beams generate two individual shades. The position of the particle relatively to the focal plane is determined from the separation of the two shades in the image plane. From the evaluation of area and contour of the shades, particles can be classified in regard to size and form. Corresponding distributions of the particles within the plasma jet as well as changes of the particle form in the melting process can be determined.

Paper Details

Date Published: 11 April 2001
PDF: 8 pages
Proc. SPIE 4308, High-Speed Imaging and Sequence Analysis III, (11 April 2001); doi: 10.1117/12.424996
Show Author Affiliations
Tilo Streibl, Univ. der Bundeswehr Muenchen (Germany)
Thomas Duda, Univ. Dortmund (Germany)
Klaus D. Landes, Univ. der Bundeswehr Muenchen (Germany)


Published in SPIE Proceedings Vol. 4308:
High-Speed Imaging and Sequence Analysis III
James S. Walton; Alan M. Frank, Editor(s)

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