General Electric Company

Lewis V McCarty

Ivan Berlec

John W Pugh

A continuous wire coating method is described which features a reaction chamber wherein a volatilized refractory metal compound is thermally decomposed to deposit said refractory metal as a coating on a refractory metal wire during passage through said reaction chamber. A substantially uniform thickness coating of the refractory metal is deposited in passing the refractory metal wire through said reaction chamber in a substantially vertical direction. The nature of said coating substantially precludes any subsequent thermal migration of the refractory metal in the wire core.

Refractory metal coating method

An improved incandescent lamp filament is described having an inner core of doped tungsten crystals with a surface layer of chemically vapor deposited undoped tungsten crystals. The inner core material exhibits the sag-resistant grain structure obtained with dispersion alloy products of tungsten whereas the unalloyed tungsten crystals in the surface layer are of a finer size and can further exhibit a preferred crystallographic orientation. Incandescent lamps utilizing said improved tungsten filaments exhibit increased vibration resistance and greater notch resistance when operated on direct current.

Incandescent lamp

An electric lamp filament of tungsten is disclosed that has been coiled and heat-treated to at least 1600.degree. 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.

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Cleveland Heights, OH, United States of America

Lewis V McCarty