Plasma spheroidization of nickel powders in a plasma reactor

Abstract. Thermal spray coatings of surfaces with metal, alloy and ceramic materials for protection against corrosion, erosion and wear is an intense field of research. The technique involves injection of the powder into a plasma flame, melting, acceleration of the powder particles, impa t and bonding with the substrate. Feed-stock powders of metals, alloys and ceramics for thermal spray applications have to meet several require-ments. Particle shape, size and its distribution, powder flow characteristics and density are the important factors to be considered in order to ensure high spray efficiency and better coating properties. For smooth and uniform feeding of powders into plasma jet, the powder particles have to be spherical in shape. High tem-peratures and steep temperatures present in thermal plasma is exploited to spheroidize particles in the pre-sent investigation. Nickel powder particles in the size range from 40–100 m were spheroidized using plasma processing. SEM and optical micrographs showed spherical shape of processed particles