Development of a powder metallurgy process for tungsten components

At present, a He-cooled divertor design for future fusion power plants is being developed at Forschungszentrum Karlsruhe. The divertor has to withstand high heat loads as well as sputtering, so that tungsten is considered to be the most promising material. Due to its high hardness, processing by standard shaping technologies, such as milling, is either difficult or even impossible. Consequently, powder injection moulding (PIM) as a method for cost-effective net shape fabrication has been adapted to tungsten.The key steps in injection moulding, such as feedstock formulation, the injection moulding process itself as well as debinding and sintering were studied. A tungsten feedstock with an optimised solid load of 55 vol.% was developed and successfully tested in moulding experiments applying complex shaped cavities. Thermal consolidation of injection-moulded components leads to a sintered density of approximately 96% and a grain size of approximately 18 μm. For final densification and grain size reduction, hot isostatic pressing (HIP) was investigated.