E. Nogues, University of Limoges / BOC Edwards, Limoges, France; P. Fauchais, M. Vardelle, University of Limoges, Limoges, France; P. Granger, BOC Edwards, Corbeil-Essonnes, France
On plasma spraying, the arc root fluctuations, modifying the length and the density of the plasma jet, have an important influence on particle thermal treatment. These voltage fluctuations are strongly linked to the cold boundary layer thickness depending to the plasma spray parameters (nature and plasma flow rate, current,…) and to the plasma torch shape (anode-nozzle internal diameter and shape,...). In order to show the influence of these different spray parameters on the cold boundary layer thickness and on the voltage fluctuations, experiments were performed with two different plasma torches from Sulzer Metco. The first one is a PTF4 torch with a conical anode-nozzle, working with Ar-H2 plasma gas mixture and the second one is a 3MB torch with both a conical and a cylindrical anode-nozzle, working with a N2-H2 plasma gas mixture.
Moreover, the arc voltage fluctuation influence on particle thermal treatment was observed by the measurement of temperature and velocity of particles, using an yttria partially stabilized zirconia powder with a size distribution between 5 to 25 µm.
The paper show the influence of different spray parameters on the cold boundary layer thickness and on the voltage fluctuations. The experiments were performed with two different plasma torches from Sulzer Metco. The first one is a PTF4 torch with a conical anode-nozzle, working with Ar-H2 plasma gas mixture and the second one is a 3MB torch with both a conical and a cylindrical anode-nozzle, working with a N2-H2 plasma gas mixture.
Moreover, the arc voltage fluctuation influence on particle thermal treatment was observed by the measurement of temperature and velocity of particles, using an yttria partially stabilized zirconia powder with a size distribution between 5 to 25 µm.
