Abstract

Plasma spray forming is recently explored as a near-net-shape fabrication route for ultra-high temperature metals and ceramics. In this study, monolithic tungsten has been produced using an atmospheric plasma spray forming and subsequent high temperature sintering. The spray-formed tungsten preform from different processing parameters has been evaluated in terms of metallurgical aspects, such as density, oxygen content and hardness. A well-defined lamellae structure was formed in the as-sprayed deposit by spreading of completely molten droplets, with incorporating small amounts of unmelted/partially-melted particles. Plasma sprayed tungsten deposit had 84-87% theoretical density and 0.2-0.3 wt.% oxygen content. Subsequent sintering at 2500°C promoted the formation of equiaxed grain structure and the production of dense preform up to 98% theoretical density.

• Keywords: Tungsten;Plasma spraying;Sintering;Oxidation;Splat structure;Equiaxed grain;