Session *BB3.4

10:15 AM *BB3.4
PLASMA SPRAYING USING THE SUPERSONIC INDUCTION PLASMA TORCH. Kim Mailhot, Francois Gitzhofer and Maher Boulos, Plasma Technology Research Centre, Department of Chemical Engineering, Universite de Sherbrooke, Sherbrooke, Quebec, CANADA.

Induction plasma technology has long been known for its potential use in material processing whether for powder densification and spheroidization, reactive in-flight processing of materials and the plasma deposition of protective coatings and near net shape parts. Its principal features are the absence of electrodes which results in the great flexibility that it offers for the control of the chemical composition of the atmosphere under which the treatment takes place. Reactive plasma deposition is a typical example where the chemical nature of the material deposited differs from that of the feed stock. Examples reported in literature include the deposition of tungstun carbide using a feed of tungstun powder and methane as powder carrier gas. Titanium carbide is another example where the reaction between the titanium feed and methane used as powder carrier gas takes place in-flight in the plasma. Common to all these applications is the caracteristic feature of induction plasmas which is known to be a low velocity plasma allowing for a long contact time between the feed material and the plasma. In the present investigation induction plasma technology is taken one step further through the attatchment of a supersonic laval type nozzel to a standard induction plasma torch. Materials processed in such a torch benifits from this added feature which results in the tremendous acceleration of the particles at the exit of the torch prior to their impact on the substrait without sacrificing the inherent, above listed, features of induction plasma technology. Examples are given in this paper of different oxide ceramic coatings which were obtained using this technique. These exhibit excelent microstructural properties.