Abstract Method of preparing tungsten, molybdenum or zirconium members such as can be used in light sources wherein a metallic member has vapor-deposited thereon additional metal by a chemical vapor deposition process. For the process of fabrication of tungsten filament wire, the required dopants can also be chemically vapor deposited in the desired concentration. There is also provided the product produced by this process. The method of chemical vapor deposition of members is particularly adapted to continuous production techniques wherein after deposition, the member is mechanically reduced to its original cross-section area and wherein a portion of the mechanically reduced material has deposited thereon additional material to provide a continuous chemical vapor deposition method preparation.
The method as specified in claim 1, wherein said elongated doped tungsten member is self-resistance heated by passing an electric current through said tungsten member.
Claim 2
Independent Claim
198 words
A method of preparing a tungsten member containing one metal selected from the group consisting of potassium, sodium, and lithium together with at least one metal oxide selected from the group consisting of silica and alumina as dopants from which lamp filament wire can be prepared, which method comprises: a. heating an elongated doped tungsten member to a temperature of 450*-1,200*C in an atmosphere comprising hydrogen, said atmosphere being a pressure of between 5 and 800 torrs and being heAted to a temperature of 300*-400*C, and surrounding said heated tungsten member with tungsten halide gas selected from the group consisting of WCl6 and WF6 which in the presence of said atmosphere comprising hydrogen will cause said tungsten halide gas to react upon contact with said heated tungsten member to deposit metallic tungsten thereon; and b. simultaneously introducing a vapor comprising one metal selected from the group consisting of K, Na and Li and at least one metal chloride selected from the group consisting of AlCl3 and SiCl4 into contact with said heated tungsten member to simultaneously deposit preselected dopant on said heated member in an atom ratio of dopant to tungsten of between 1 ppm and 500 ppm.
Claim 3
Dependent Claim
19 words
The method as specified in claim 3, wherein said vapor consists essentially of water vapor, SiCl4, AlCl3, and K.