Production of fine metal and ceramic powders by the plasma melt and rapid solidification (PMRS) process

Abstract

Ultra-fine metal and ceramic powders are of technological importance because of the ease in using them in the forming of near-net-shape components and because products would require shorter firing cycles. This paper reports the production of fine stainless steel (AISI 316) and yttria-stabilised zirconia (ZrO 2-8 wt% Y 2O 3) powders using the plasma melt and rapid solidification (PMRS) process. The initial feedstock with a size range of 45−150 μm is injected into a thermal plasma jet stream where the powders become molten and are ejected at high velocity towards a rotating target. Fragmentation of the molten particles upon impact results fine, spherical powders in the size range <1–50 μm. Various process parameters affecting the average particle size and the percentage of spherical powders have been investigated. Preliminary results show that the type of powder feed anode, the substrate rotating speed, the substrate material and the plasma gas composition are the major factors that influence the successful production of fine and spherical powders.