Process of manufacturing a tungsten lamp filament

摘要

An electric lamp filament of tungsten is disclosed that has been coiled and heat-treated to at least 1600 DEG C. on a wire mandrel containing molybdenum but which is essentially free of molybdenum contamination. A barrier layer of tungsten or tantalum is provided on said mandrel to preclude the molybdenum contamination and the coated mandrel can thereafter be dissolved from the uncontaminated tungsten filament coil in an acid mixture.