Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01K—ELECTRIC INCANDESCENT LAMPS
  • H01K1/00—Details
  • H01K1/02—Incandescent bodies
  • H01K1/04—Incandescent bodies characterised by the material thereof
  • H01K1/10—Bodies of metal or carbon combined with other substance
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/045—Alloys based on refractory metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
  • C22C27/04—Alloys based on tungsten or molybdenum
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01K—ELECTRIC INCANDESCENT LAMPS
  • H01K1/00—Details
  • H01K1/02—Incandescent bodies
  • H01K1/04—Incandescent bodies characterised by the material thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01K—ELECTRIC INCANDESCENT LAMPS
  • H01K3/00—Apparatus or processes adapted to the manufacture, installing, removal, or maintenance of incandescent lamps or parts thereof
  • H01K3/02—Manufacture of incandescent bodies

Definitions

• ABSTRACT Sintered tungsten filaments for incandescent lamps contain as dopants 0.01-100 ppm beryllium, at least one of 10-100 ppm potassium or 0.1-l0 ppm thallium, and at least one of 0.5-2 ppm of alluminum or 0.01-5 ppm gallium. These have greater strength than the corresponding alloys in which silicon is present instead of beryllium. Any silicon in the present invention will be less than half the beryllium by weight.
• the invention relates to a tungsten incandescent body containing foreign substances, which is in a recrystallized state, and has high strength at room temperature.
• illuminating tungsten filament incandescent lamps such as gas-filled double-coil lamps, halogen-containing incandescent lamps, etc.
• Tungsten wire characteristics corresponding to the requirements of incandescent lamp production are today generally attained by the addition of not more than all together one percent of an additive material composed of compounds containing K, Si and Al to the base material of the tungsten wire: the W or the blue oxide/e.g. WO the thus achieved so called doped base material is then reduced to doped tungsten metal powder by heating it in a stream of hydrogen.
• the majority of the said additive material is thereafter removed from such metal powders by washing them out and porous bars are pressed from it.
• the porous bars are pressed from the doped metal powder without washing it out.
• additives is applied to those chemical materials which contain (foreign) atom species different from tungsten and which are added to the starting material for the preparation of the tungsten wire.
• the residual traces of these which are present in the prepared tungsten wire are termed foreign materials, even when they contain foreign atoms themselves different from tungsten, and when these consist of a chemical compound or compounds of the foreign atom species different from tungsten.
• impurities traces of substances or residues of these being present as non-additives but natural impurities, are hereafter called impurities.
• the aim of the present invention was to improve the strength of tungsten wires in their recrystallized state at normal (room) temperatures. It was found that this aim can be achieved by modifying the foreign materials hitherto used in tungsten.
• the foreign materials form solid-phase molecules in the tungsten metal, and give rise to the favourable recrystallization properties, etc., by being situated initially on the surface of the fibres of the drawn tungsten wires. It is considered possible that the composition of the molecules is KAlSi O that is it corresponds to the composition of the mineral leucite.
• the foreign materials similarly form solid-phase molecules, and give rise to the recrystallization and other favourable properties by finally being dispersed throughout the tungsten metal.
• the molecules have diamaters of about 400 A, while their composition is 3Al O .2SiO approximately the same as that of the mineral mullite.
• a network of spherical micropores can be found in recrystallized tungsten metal doped with foreign materials containing K, Si and Al; and according to the most recent observations these pores contain elemental potassium.
• the network of micropores may give rise to the recrystallization and other favourable properties in tungsten metal doped with foreign materials containing K, Si and Al in just the same way as the above-mentioned network of foreign-phase molecules.
• the diameters of the spherical micropores are about A.
• a tungsten metal powder was therefore prepared by the addition of an aqueous solution of KCl, BeCl and Al Cl to the W0 base material, with the aim of examining whether, by replacing the SiO with BeO which is even more difficult to reduce with hydrogen, the large-crystalline structure would remain and other properties better than those already known would appear.
• the additive-containing aqueous paste was dried, the doped W0 was reduced with hydrogen, a bar was pressed from the metal powder formed, and this was then sintered by the passage of an electric current.
• the sintered bar was worked into incandescent lamp wires by swaging and wire-drawing.
• the tungsten wires prepared according to the invention do not contain considerable amounts (either as impurities or as foreign materials) of Si or compounds containing Si, but do contain, and precisely instead of it, foreign material containing Be; in this way the wires differ primarily from the tungsten wires prepared with the foreign materials Be SiO or BeSiO according to the British Pat.
• the beryllium content of the tungsten wire according to the invention was at least 0.000001 percent, that is 0.01 ppm. It was also observed that to avoid the disturbing effect of silicon-containing foreign material or impurity traces and thus for the necessary attainment of the favourable effect of the beryllium-containing siliconfree additive, it was sufficient if the silicon content of the tungsten wires according to the invention was less than half the beryllium content so as to ensure a considerable beryllium content being independent from the Si content.
• Our invention is thus a foreign material-containing tungsten incandescent body, which is in a recrystallized state, has high strength at room temperature, and is characterized by the facts that one of the foreign materials contains beryllium, that the beryllium content of the tungsten incandescent body is 0.01-100 ppm, and that the silicon content (impurity) is less than half the beryllium content.
• the procedure for the preparation of the tungsten incandescent body according to the invention is characterized by the fact that a silicon-free beryllium compound is added as one of the additives, in a proportion of 100l0,000 ppm calculated as beryllium oxide, to a tungsten oxide the silicon dioxide impurity of which does not exceed the amount corresponding to the atomic ratio one silicon to six berylliums, and the tungsten oxide is itself then reduced to metal powder, pressed, sintered and swaged, and finally formed into wire by wire-drawing and hence into an incandescent body, by known methods.
• the preparation of the tungsten incandescent body according to the invention can also be carried out in such a way that the silicon dioxide impurity content is adjusted to less than the amount corresponding to the atomic ratio one silicon to six berylliums by the washing out of the reduced metal powder or the partially sintered metal body, for example by the washing out with a hydrofluoric acid solution by a known method.
• a maximum of about one-sixth part of the beryllium content in the incandescent body may be bound by the silicon. It follows from the atomic weights of beryllium and silicon that for 90.2 parts by weight of beryllium to form beryllium silicate of composition BeSiO in its complete entirety, 280.6 parts by weight of silicon are necessary. Thus, 45 .1 parts by weight of silicon, i.e. half of 90.2 parts by weight, bind 45.1 /280.6, i.e. approximately one-sixth part of 90.2 parts by weight of the beryllium amount.
• tungsten wire and tungsten incandescent body are understood a tungsten wire and a tungsten incandescent body which in addition to the proposed Be-containing foreign materials also contain one or more other foreign materials, such as for example foreign materials containing K and- /or Al, or K and or Ga, as well as for example Tl and/or A, or Tl and/or Ga, etc., but does not contain silicon only as an impurity (if it does).
• Tungsten wires prepared with the foreign material quartet combination containing for example K, Be, Al and Ga according to the invention are large-crystalline on recrystallization, and their good properties attain and even exceed the good properties of known tungsten wires prepared with the foreign material trio combination containing K, Si and Al; in addition to this their strength in the recrystallized state at room temperature is substantially better than such strength of known recrystallized tungsten wires prepared with the foreign material trio K, Si and Al.
• EXAMPLE 1 A 0.3% aqueous solution of KCl, an aqueous solution of beryllium chloride corresponding to 0.20% BeO, and an aqueous solution of aluminum chloride corresponding to 0.05% A1 0 calculated with respect to the W0 are added to a dilute aqueous paste of W0 powder prepared by heating from ammonium paratungstate (the so-called para-crystals), and then tungsten metal powder is made from this in the normal way, that is by drying and by reduction with hydrogen. Bars are pressed from the metal powder, and these are sintered to make them compact by heating them with an electric current in hydrogen gas. The bars thus prepared contain approximately O.10-10.0 ppm Be, 1-2 ppm Al and 10-100 ppm K.
• EXAMPLE 2 An aqueous solution of thallium/l/nitrate corresponding to 0.1% T1, an aqueous solution of beryllium chloride corresponding to 0.20% BeO and an aqueous solution of aluminum chloride corresponding to 0.05% A1 0 calculated with respect to the W0 are added to a dilute aqueous paste of blue oxide powder of composition W0 prepared from para-crystals by heating and mild reduction, and then from this by the method of Example 1 compact, sintered tungsten bars are prepared. Such bars contain approximately 0.10-10.0 ppm Be, 1-2 ppm Aland 0.0110.0 ppm Tl.
• EXAMPLE 3 A 0.3% aquoeus solution of KCl, an aqueous solution of beryllium nitrate corresponding to 0.20% BeO and an aqueous solution of gallium nitrate corresponding to 0.03% Ga O calculated with respect to the W0 are added to a dilute aqueous paste of blue oxide" powder of composition W0 obtained from para-crystals by heating and mild reduction, and then from this by the method of Example 1 compact, sintered tungsten bars are prepared. Bars so prepared contain approximately 0. l0-10.0 ppm Be, 0.01-5 ppm Ga and 10-100 ppm K.
• EXAMPLE 4 An aqueous solution of thallium/l/nitrate corresponding to 0.1% Tl, an aqueous solution of beryllium nitrate corresponding to 0.20% BeO and an aqueous solution of gallium nitrate corresponding to 0.03% Ga O calculated with respect to the W are added to a dilute aqueous paste of W0 powder prepared from para-crystals by heating, and then from this by the method of Example 1 compact, sintered tungsten bars are prepared. Bars so prepared contain approximately 010-100 ppm Be, 0.0l ppm Ga and 01-100 ppm Tl.
• EXAMPLE 6 A 0.3 aqueous solution of KCl, an aqueous solution of beryllium chloride corresponding to 0.02% BeO and an aqueous solution of gallium nitrate corresponding to 0.03% Ga O calculated with respect to the W0 are added to a dilute aqueous paste of blue oxide powder of composition W0 prepared from paracrystals by heating and mild reduction, and then from this by the procedure of Example 1 compact, sintered tungsten bars are prepared. Bars so prepared contain approximately 0.0ll.0 ppm Be, 0.01-5 ppm Ga and 10-50 ppm K.
• EXAMPLE 8 An aqueous solution of thallium/I/nitrate corresponding to 0.1% Tl, an aqueous solution of beryllium nitrate corresponding to 0.02% BeO and an aqueous solution of gallium nitrate corresponding to 0.03% Ga O calculated with respect to the W0 are added to a dilute aqueous paste of WO .l-l O precipitated with boiling hydrochloric acid from a boiling aqueous solution of Na WO and then from this by the method of example 1 compact, sintered tungsten bars are prepared.
• Bars so prepared contain approximately 0.0ll.0 ppm Be, 0.0l-1.0 ppm Ga and 0.1-1.0 ppm EXAMPLE 9
• a 0.3% aqueous solution of KCl, an aqueous solution of BeCl corresponding to 0.02% BeO, an aqueous solution of Al Cl corresponding to 0.03% A1 0 and an aqueous solution of gallium nitrate corresponding to 0.03% Ga O calculated with respect to the W0 are added to a dilute aqueous paste of blue oxide powder of composition W0 prepared from para-crystals by heating and mild reduction, and then from this by the procedure of Example 1 compact, sintered tungsten bars are prepared.
• Bars so prepared contain approximately 0.0l-l.0 ppm beryllium, 0.5-1.0 ppm aluminium, 0.0l5.0 ppm gallium and l050 ppm potassium.
• Beryllium tungsten bars prepared according to Examples l to 8 and 9 are swaged and worked into drawn wire, and from this coil-shaped incandescent bodies with a wire diameter of 0.3 mm for example, and also 220 V/40 W double coils with a wire diameter of 0.014 mm are prepared; it is observed that in these on recrystallization a structure develops which consists of crystals much longer than the wire diameter.
• the other properties of such beryllium tungsten incandescent bodies in general attain the good properties of silicon tungsten incandescent bodies prepared with foreign materials containing K, Si and Al.
• the roomtemperature strength of the recrystallized beryllium tungsten incandescent bodies far exceeds those of recrystallized silicon tungsten incandescent bodies: while 220 V/40 W recrystallized double coils prepared with foreign materials containing K, Si and Al can be drawn out to about twice their original length at room temperature without breaking, the beryllium tungsten recrystallized 220 V/40 W double coils can be drawn out on average to three-four times their original length.
• Incandescent bodies for example 220 V/40 W double coils, can be prepared from the beryllium tungsten bars made with foreign material containing Tl, but without foreign material containing K, as in Examples 2, 4, 6 and 8, such that they do not burn out by arcing in gas-filled incandescent lamps among others corresponding to the description in the Hungarian Pat. No. 155,352 (4), not even if they are connected in the first instance directly at the maximum incandescent filament temperature, which causes burn out by arcing almost without exception in the case of incandescent filaments prepared with foreign materials containing K, Si, and Al. Foreign material containing Be does not mar the favourable effect of foreign material containing Tl.
• wires of beryllium tungsten bars prepared according to Examples 6 and 8 are particularly suitable for incandescent bodies of incandescent lamps containing halogen, in which in addition to a crystal structure ensuring retention of shape it is also desirable (in order to ensure the non-disturbance of the gas-space processes) to maintain the possibly evaporating foreign material content of the incandescent filaments at en extremely low level.
• a sintered tungsten incandescent body containing 0.01- ppm beryllium, at least one member selected from the group consisting of 10-100 ppm potassium and 0.1-10 ppm thallium, and at least one member selected from the group consisting of O.52 ppm of aluminum and 0.01-5 ppm gallium, containing less than half as much silicon as beryllium by weight, balance essentially tungsten.

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• Engineering & Computer Science (AREA)
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• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)
• Radiation-Therapy Devices (AREA)

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Cited By (4)

Citations (9)

• 1972
  • 1972-03-16 HU HUMA2339A patent/HU163582B/hu unknown
  • 1972-06-27 US US00266578A patent/US3853492A/en not_active Expired - Lifetime
  • 1972-09-18 AT AT800072A patent/AT316686B/de active
  • 1972-09-20 DE DE2246092A patent/DE2246092A1/de active Pending
• 1973
  • 1973-03-07 GB GB1119873A patent/GB1397865A/en not_active Expired
  • 1973-03-15 FR FR7309382A patent/FR2221812B1/fr not_active Expired
  • 1973-03-15 NL NL7303655A patent/NL7303655A/xx unknown

Patent Citations (9)

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