| Abstract: |
It is well-known that size distribution of spraying powder affects the coating structure and properties significantly; a smaller?sized powder, in general, results in high quality of the coating. Some studies on a new thermal spray process called suspension plasma spray (SPS) are carried out and reported to spray with smaller particles.
In this study, a suspension spraying was carried out with using the very unique system called ?Twin-cathode Type Plasma Spray Gun? (Aeroplasma Corporation, Japan). This plasma spray gun equips three plasma torches; one ?P-torch? with a reversed polarity (i.e. a cathodic nozzle and an anodic electrode), and a pair of ?N-torches? with a normal polarity. During the operation in this system, electric power is supplied between an anode of P-torch and two cathodes of N-torches, so that plasma jet can be maintained with a very unique shape of arc between P- and N-torches. Since this anode of P-torch is a hollowed electrode, axial feeding of spraying materials is available.
A suspension of fine yttria powder with ethanol was sprayed onto the steel substrate with using this plasma gun, and the relationship between spray parameters (such as plasma gas flow rate, electric power input, nozzle shape, amount of yttria, and so on) and microstructure of the deposits were evaluated. Detailed results will be presented at the conference.
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