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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

2004, Volume8

178 pages

DOI: 10.1615/HighTempMatProc.v8.i1

Issue price - $144.00

UNDERSTANDING OF SUSPENSION PLASMA SPRAYING

V. Rat
PCTS -CNRS UMR 6638, University of Limoges, 123 av. A. Thomas, 87060 Limoges cedex, France

C. Delbos
Laboratoire Sciences des Precedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS-Universite de Limoges, conventionne avec le CEA n° M08

C. Bonhomme
Laboratoire Sciences des Precedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS-Universite de Limoges, conventionne avec le CEA n° M08

J. Fazilleau
Laboratoire Sciences des Precedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS-Universite de Limoges, conventionne avec le CEA n° M08

J. F. Coudert
PCTS -CNRS UMR 6638, University of Limoges, 123 av. A. Thomas, 87060 Limoges cedex, France

Pierre Fauchais
Laboratoire Sciences des Precedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS-Universite de Limoges, faculte des Sciences et Technique, conventionne avec le CEA n° M08, France

ABSTRACT

The aim of this paper is to present the recent advances regarding the Suspension Plasma Spraying process (SPS). The latter is devoted to synthesize finely structured coatings which are of great interest for the electrolytes (of low thickness, 20-30 μm) of Solid Oxide Fuel Cells (SOFC). Powders of Yttria (13.5wt%) Stabilised Zirconia (YSZ) are dispersed in ethanol to produce a stable suspension. The latter is injected by using a mechanical injection into a plasma jet generated by a DC plasma torch. Four centimetre square coatings are built with a deposition efficiency ranging between 50 and 60 % and a deposition rate up to 15 μm.h⁻¹.m⁻².
The injection pressure of suspensions is optimized by using a pulsed infra-red illumination of the atomization processes of suspensions which is observed with a fast shutter camera.
The influences of the preheating and roughness of the substrates, the plasma gas composition and the particle size distribution on the flattening degree of collected splats are investigated. Moreover, the effect of these experimental parameters on the coating microstructures is then studied. It is shown that substrates have to be polished and preheated to enable the most favorable flattening of splats. Moreover, the particle size distribution of powder in suspension has to be narrow with a size adapted to the spraying conditions, for example, centered on about l μm for a plasma enthalpy of 17.5 MJ.kg⁻¹. The results about splats are confirmed when analyzing coating microstructures which present micro-sized porosity.