Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Patent
1983-09-19
1985-12-17
O'Keefe, Veronica
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
428620, 428661, 428663, H01J 1716, C23C 500, C25D 500
Patent
active
045592780
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a current inlet conductor made of molybdenum covered by an intermediate metal coating at least on a part to be welded. The current inlet conductor according to the invention serves particularly in vacuum devices, e.g. in electric light sources for passing electric current through vitreous material, wherein the conductor can be tighted hermetically. The invention relates further to a method of producing the proposed current inlet conductor.
BACKGROUND OF THE INVENTION
The main requirements for current inlet conductors in the field of vacuum lamps are the following:
The current inlet conductor passed through a vitreous material closing device is generally to be connected to an element made of any metal in the innerspace of the device. The connection should be characterized by a defined level of mechanical and electrical features. In the case of electric light sources the electric inlet conductor is usually connected by welding, particularly by resistance welding to the metallic element. The principal requirement is consequently high weldability. Another requirement can be drafted as follows: the current inlet conductor should be capable of being surrounded and wetted by a vitreous material in order to produce a hermetic seal. The current inlet conductors of the vacuum devices are most generally made of molybdenum. In vacuum devices, for example, such as high-pressure gas discharge lamps or halogenide lamps comprising a bulb made of quartz glass, thin plates or foils made of molybdenum are used for supplying electric current to the electrodes. In the case of light sources with bulbs made of hard glass or in electronic tubes, molybdenum wires are generally used. In order to facilitate welding of the molybdenum parts and to improve the quality of binding to elements made of molybdenum, the molybdenum element characterized by low weldability is covered with an intermediate metal coating. Another possibility lies in applying between the surfaces to be connected to one another, an element made of intermediate metal of required characteristics. The material of the intermediate metal coating or element is chosen in order to ensure required mechanical features such as strength and toughness at higher temperatures of operation. These requirements especially in the case of halogenic lamps or lamps with metallic halogenic filling, are to resistance against the atmosphere surrounding the metallic element. According to the art the more widely used intermediate metals are tantalum and platinum, however, in the literature it is mentioned that the use of zirconium, rhodium, nickel, gold or palladium and the alloys thereof can be advantageous (e.g. W. Espe: "Material of High Vacuum Technology", Vol. 1., Ch. 9, Pergamon Press, 1966).
When applying a special intermediate point made of a required metal, it is obvious that a further element should be taken into account during production in that the metal has to be supplied at the place of operation and positioned according to the requirements. The process is thereby made more complex than without the coating step. It is an obvious simplifying step to cover the elements made of molybdenum with a coating of intermediate metal at least on the surface parts where welding is to be later applied. The coating should be prepared before applying the element for production of the light source. The French Patent Specification No. 2 079 541 proposes the previous covering of the molybdenum foil by lubricating the surface of the foil with a solution of a platinum alloy which can be fixed by following with heat treatment.
The published West German Patent Specification No. DE-OS 31 04 043 discloses a method of preparing the coating on the surface of a molybdenum foil by vacuum sputtering or evaporation of a suitable metal. This specification discloses also the use of platinum, and further of tantalum, gold and rhenium. These metals are mentioned as to be theoretically suitable for preparing a coating. The vacuum sputtered or evaporated coating
REFERENCES:
patent: 2113984 (1936-04-01), Harris et al.
patent: 2859562 (1958-11-01), Dorgelo et al.
patent: 3386159 (1968-06-01), Milch et al.
patent: 3504426 (1970-04-01), Craig et al.
patent: 4277716 (1981-07-01), Banks
Handbook of Galvanic Coating in Mechanical Engineering-Moscow, 1979-translation of pp. 88 to 90.
Nagy Janos
Nagy Laszlo
Oldal Endre
Dubno Herbert
O'Keefe Veronica
Ross Karl F.
Tungsram Reszvenytarsasag Abr. Tungsram Rt.
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