Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/16—Acidic compositions
  • C23F1/26—Acidic compositions for etching refractory metals
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/04—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in markedly acid liquids
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4981—Utilizing transitory attached element or associated separate material

Definitions

• Gaseous nitrogen oxides generated at the time of dissolution of the mandrel wire of a filament coil can be accurately removed by adding an inhibitor for generation of gaseous nitrogen oxides to a resolving solution comprising nitric acid, water and at least one member selected from sulfuric, hydrochloric and phosphoric acids for dissolving the mandrel wire.
• an inhibitor for generation of gaseous nitrogen oxides to a resolving solution comprising nitric acid, water and at least one member selected from sulfuric, hydrochloric and phosphoric acids for dissolving the mandrel wire.
• said inhibitor are an oxidizing agent composed of an inorganic peroxide such as permanganic acid salt or perchloric acid salt and inorganic or organic reducing agents.
• a filament coil used as the electrode of such light source as incandescent lamp or fluorescent discharge lamp or such electron tube as vacuum tube is produced by winding a fine tungsten wire around a mandrel wire to form a coil and, if necessary, further winding the thus formed coil around other mandrel wire to form a desired coil, e.g. a single or multiple coil.
• the mandrel wire, which has been used to form the tungsten wire into a desired filament coil is required to be removed after formation of the filament coil.
• the mandrel wire is required to satisfy such conditions that it can withstand the heat treatment temperature for removal of internal strain of the tungsten wire and can be easily dissolved after formation of filament coil.
• metals satisfying the above conditions there are molybdenum and nickel silver (an alloy comprising 45 to 65 percent of Cu, 6 to 35 percent of Ni, to 35 percent of Zn and slight amounts of Mn, Fe and Pb; m.p.
• the'heat treatment of the tungsten wire after formation of coil is preferably effected at a temperature as high as possible.
• a molybdenum wire having a melting point of 2,610C. is used as the mandrel wire.
• the heat treatment is conducted at 800C. or above.
• the nickel silver is suitable as a mandrel wire for formation of such filament coil.
• a filament coil is produced by winding a tungsten wire around a mandrel wire to form a coil, heat-treating the coil to remove the internal strain of the tungsten wire and then removing the mandrel wire from the interior of the coil. I-Ieretofore, the mandrel wire has been removed by dissolving said wire with a resolving solution comprising nitric acid, sulfuric acid and water.
• a molybdenum wire is used as the mandrel wire
• a filament coil having the molybdenum mandrel wire inside the coil is charged into a resolving solution comprising 3.75 parts by weight of 98 percent nitric acid, 2.7 parts by weight of 98 percent sulfuric acid and 1 part by weight of water, and then the solution is heated to dissolve the molybdenum mandrel wire.
• a resolving solution comprising 3.75 parts by weight of 98 percent nitric acid, 2.7 parts by weight of 98 percent sulfuric acid and 1 part by weight of water
• the nitric acid in the resolving solution is gradually converted to nitrous acid with dissolution of the mandrel wire, and said nitrous acid generates large amounts of various gaseous nitrogen oxides such as, for example, NO and N0
• gaseous nitrogen oxides are harmful and give injuries to the human body and living things when liberated into the air, so that it is extremely important from the standpoint of environment sanitation to not liberate such air-polluting substances into the air.
• the gaseous nitrogen oxides generated at the time of dissolution of mandrel wire have been removed by washing air containing said gaseous nitrogen oxides with water or alkali solution, but it has been impossible to completely remove said oxides because the washing power is insufficient and long treatment time and enormous installations are required.
• the dissolving operation of the mandrel wire inside the aforesaid filament coil is carried out in a room, so that it is necessary for sanitary reasons to not allow the gaseous nitrogen oxides to stay in the room. Accordingly, the gaseous nitrogen oxides are discharged out of the room by use of a strong suction means.
• the present invention relates to a process for accurately removing, overcoming the drawbacks of the prior art process and by a simple procedure, gaseous nitrogen oxides generated at the time of dissolution of the mandrel wire of a filament coil, in which process an inhibitor for generation of gaseous nitrogen oxides is added to a resolving solution for dissolving the mandrel wire to inhibit the formation of nitrous acid, which becomes a source for generation of gaseous nitrogen oxides at the time of dissolution of the mandrel wire, and nitrous acid formed is converted by means of said inhibitor into nitric acid or decomposed into harmless substances such as nitrogen, carbon dioxide, water and the like to prevent the liberation of gaseous nitrogen oxides into the air.
• An object of the present invention is to provide a process for dissolving the mandrel 'wire of a filament coil without generation of air-polluting substances, in which process an inhibitor for generation of gaseous nitrogen oxides is added to a resolving solution for dissolving the mandrel wire to simply prevent the generation of gaseous nitrogen oxides.
• Another object of the invention is to provide a process for dissolving the mandrel wire of a filament coil in which process gaseous nitrogen oxides which become causes for air pollution are completely inhibited from generation and are prevented from being liberated into the air.
• a further object of the invention is to provide a process for dissolving the mandrel wire of a filament coil, in which process an inhibitor for generation of gaseous nitrogen oxides is added to an aqueous solution containing nitric acid to form a resolving solution for dissolving the mandrel wire, so that in dissolving the mandrel wire with said resolving solution, nitrous acid derived from the nitric acid is inhibited by means of said inhibitor from being converted into gaseous nitrogen oxides and is converted into other harmless substances, thereby preventing the generation of harmful gases.
• a still further object of the invention is to provide a process for dissolving the mandrel wire of a filament coil, in which process the dissolution of tungsten wire constituting the filament coil is prevented to obtain a filament coil less in weight loss and stable in efficiency.
• This invention relates to a process for dissolving the mandrel wire of a filament coil by means of a resolving solution comprising nitric acid, water and at least one member selected from sulfuric, hydrochloric acid, phosphoric acids, characterized in that the resolving solution is incorporated with an inhibitor for generation of gaseous nitrogen oxides, and nitrous acid formed in the dissolving step which becomes a cause for generation of gaseous nitrogen oxides is converted by means of said inhibitor into nitric acid or decomposed into harmless substances such as nitrogen, carbon dioxide, water and the like, so that no gaseous nitrogen oxides are formed and liberated into the air.
• the resolving solution is prepared by adding to the above-mentioned aqueous nitric acid solution or nitric acid-containing solution at least one oxidizing agent composed of an inorganic peroxide such as permanganic acid salt or potassium perchlorate, at least one inorganic reducing agent composed of an ammonium salt such as ammonium nitrate, ammonium chloride, ammonium sulfate or ammonium phosphate, at least one organic reducing agent composed of urea or oxalic acid, or a combination ofsaid inorganic reducing agent and organic reducing agent.
• an oxidizing agent composed of an inorganic peroxide such as permanganic acid salt or potassium perchlorate
• at least one inorganic reducing agent composed of an ammonium salt such as ammonium nitrate, ammonium chloride, ammonium sulfate or ammonium phosphate
• at least one organic reducing agent composed of urea or oxalic
• a filament coil produced by winding a tungsten wire around a mandrel wire made of molybdenum or nickel silver to dissolve the mandrel wire with the resolving solution.
• the resolving solution reacts with the mandrel wire, whereby the nitric acid becomes nitrous acid.
• the thus formed nitrous acid is decomposed to form gaseous nitrogen oxides (NO, N N0
• the nitrous acid is converted into nitric acid by means of the aforesaid oxidizing agent in the resolving solution, or is decomposed into water and an entirely harmless gas such as nitrogen or a mixture of nitrogen and carbon dioxide by means of the aforesaid inorganic or organic reducing agent in the resolving solution, so that the nitrous acid is prevented from being liberated as gaseous nitrogen oxides into the air.
• EXAMPLE 1 To an aqueous solution comprising 29 g. of 62 percent nitric acid and 87 g. of water was added 8 g. of potassium permanganate as an inhibitor for generation of gaseous nitrogen oxides to prepare a resolving solution mixture.
• a double coil filament prepared by winding a tungsten wire around a molybdenum mandrel wire (molybdenum weight 4 g.), whereby the molybdenum mandrel wire was completely dissolved and, nitrous acid formed in the resolving solution was converted into nitric acid by the oxidizing power of the potassium permanganate, and there was scarcely the case where the nitrous acid was decomposed to gaseous nitrogen oxides and liberated into the air.
• the double coil filament taken out of the resolving solution after dissolution of the mandrel wire had more or less amount of a deposit on the surface. When the deposit was removed by acid-washing, however, there was obtained a filament for incandescent lamp which was substantially identical in efficiency with that obtained by washing the double coil filament with a resolving solution comprising nitric acid, sulfuric acid and water.
• the resolving solution after dissolution of the mandrel wire was analyzed to detect no tungsten. F rom this, it was confirmed that the resolving solution used in this example to dissolve the mandrel wire did not dissolve the tungsten wire even partly to bring about no decrease in weight of. the resulting filament coil and thus gave no detrimental effect to the filament coil.
• EXAMPLE 2 The molybdenum mandrel wire of the same double coil filament as in Example 1 was dissolved by use of a resolving solution comprising 29 g. of 62 percent nitric acid, 2.5 g. of 98 percent sulfuric acid, 87 g. of water and 8 g. of potassium permanganate, whereby the dissolution was completed within about 15 minutes.
• EXAMPLE 3 The molybdenum mandrel wire of the same double coil filament as in Example 1 was dissolved by use of a resolving solution comprising 29 g. of 62 percent nitric acid, 2.5 g. of 98 percent sulfuric acid, 87 g. of water, 8 g. of potassium permanganate and l g. of potassium perchlorate (commercially available product), whereby the dissolution was complete within about l0 minutes. r
• the potassium perchlorate formed a mixed crystal with the potassium permanganate and converted the formed nitrous acid into nitric acid to display the action of preventing the generation of gaseous nitrogen oxide, like the potassium permanganate.
• the potassium perchlorate was strong in oxidizing power, so that the time of dissolving the molybdenum mandrel wire could be shortened.
• EXAMPLE 4 A resolving solution comprising 25 g. of 85 percent phosphoric acid, 29 g. of 62 percent nitric acid, 70 g. of water and g. of ammonium chloride was maintained at below 80C., and a double coil filament having a molybdenum mandrel wire of 3 g. in weight was charged in said solution to dissolve the mandrel wire, whereby the dissolution was complete within about 20 minutes.
• nitrous acid was formed, but the ammonium chloride acted as a decomposing agent to decompose the nitrous acid into nitrogen gas and water, and prevented said acid from converting into gaseous nitrogen oxides, so that the amounts of gaseous nitrogen oxides liberated into the air were quite slight.
• the resolving solution after dissolution of the molybdenum mandrel wire was analyzed, whereby tungsten was detected to confirm that a part of the filament coil had been dissolved.
• the amount of dissolved filament coil was quite slight and weight loss of the filament coil was not such an extent as to give any detrimental effect to the characteristics of the filament coil when used as an electrode for light source.
• EXAMPLE 5 A resolving solution comprising 25 g. of 85 percent phosphoric acid, 25 g. of 62 percent nitric acid, 65 g. of water and 3.5 g. of ammonium sulfate was maintained at below about 80C. and was used to dissolve the molybdenum mandrel wire of the double coil filament used in Example 4, whereby the dissolution of the mandrel wire was complete within about minutes.
• EXAMPLE 6 A resolving solution comprising 10 g. of 85 percent phosphoric acid, 25 g. of 62 percent nitric acid, 70 g. of water, l0 g. of ammonium phosphate and 10 g. of ammonium nitrate was maintained at below about 90C. and was used to dissolve the molybdenum mandrel wire of the double coil filament used in Example 4, whereby the dissolution of the mandrel wire was complete within about 10 minutes.
• EXAMPLE 7 A resolving solution comprising 15 g. of 62 percent nitric acid, g. of 98 percent sulfuric acid, 65 g. of water and 4 g. of ammonium sulfate was maintained below about 70C. and was used to dissolve the molybdenum mandrel wire of the double coil filament used in Example 4, whereby the dissolution was complete within about minutes.
• EXAMPLE 8 A resolving solution comprising 20 g. of 62 percent nitric acid, 15 g. of hydrochloric acid, 65 g. of water and 5 g. of ammonium chloride was maintained below about 70C. and was used to dissolve the molybdenum mandrel wire of the double coil filament used in Example 4, whereby the dissolution was complete within about 25 minutes.
• EXAMPLE 9 A resolving solution comprising 10 g. of 62 percent nitric acid, g. of water and 4 g. of urea was maintained at below about C. and was used to dissolve the molybdenum mandrel core (2 g.) of a double coil filament, whereby the dissolution of the mandrel wire was complete within about 20 minutes.
• nitrous acid which is easily converted into gaseous nitrogen oxides, was formed at the time of dissolution of the mandrel wire, said acid was decomposed into nitrogen, carbon dioxide by the reducing action of the urea, and the amounts of gaseous nitrogen oxides liberated into the air were so slight as to bring about no cause for air pollution.
• the resolving solution after dissolution of the molybdenum mandrel wire was analyzed, whereby tungsten was detected to find that a part of the tungsten wire constituting the filament coil had been dissolved.
• the amount of dissolved tungsten wire was not more than 0.5 percent of the theoretical amount and was not such an extent as to injure the efficiency of the filament coil.
• EXAMPLE 10 An aqueous solution containing 86 g. of 85 percent phosphoric acid, 10 g. of 62 percent nitric acid and 3 g. of urea was maintained at below about 90C., and was used to dissolve the molybdenum mandrel wire (molybdenum weight 1.5 g.) of a double coil filament, whereby themandrel wire could be dissolved within about 15 minutes.
• molybdenum mandrel wire molybdenum weight 1.5 g.
• EXAMPLE 1 l A resolving solution comprising 67 g. of 85 percent phosphoric acid, 8 g. of 62 percent nitric acid, 25 g. of water and 2.5 g. of urea was maintained at below about C., and was used to dissolve the molybdenum man drel wire (2 g.) of a double coil filament, whereby the dissolution was complete within about 25 minutes.
• Example 10 the urea acted, like in Example 9, as a decomposing agent for nitrous acid, which becomes a cause for generation of gaseous nitrogen oxides, and decomposed said acid into harmless nitrogen and carbon dioxide, and there was scarcely the case where gaseous nitrogen oxides were liberated into the air. Moreover, the weight loss of the tungsten wire was quite slight.
• the double coil filament of Example ll was used as an electrode for fluorescent discharge lamp to find that the filament was not injured in efficiency as the electrode.
• the present invention is applicable to the cases where the mandrel wire of a filament coil composed of a tungsten wire is dissolved by means of a resolving solution containing nitric acid, and the mandrel wires usable in the present invention are not limited only to molybdenum and nickel silver wires but include other materials that can be used as mandrel wires.
• washing said filament coil comprising adding an inhibitor to the resolving solution to prevent generation of gaseous nitrogen oxides at the time of dissolution of the mandrel wire, the inhibitor consisting essentially of an inorganic peroxide, an ammonium salt or an organic reducing agent.
• said resolving solution additionally contains at least one member selected from the group consisting of sulfuric acid, hydrochloric acid and phosphoric acid.
• the inorganic peroxide is at least one member selected from the group consisting of permanganic acid salt and perchloric acid salt.
• the inhibitor is at least one member selected from the group consisting of ammonium nitrate, ammonium chloride, ammonium sulfate and ammonium phosphate.
• organic reducing agent is at least one member selected from the group consisting of urea and oxylic acid.
• mandrel wire is made from molybdenum or nickel silver.
• said inhibitor is selected from the group consisting of potassium permanganate, potassium perchlorate, ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium nitrate, urea and mixtures thereof.
• mandrel wire is a nickel silver alloy comprising about 45 to 65 percent copper, 60 to 35 percent nickel and 15 to 35 percent zinc.

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• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

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Citations (3)

• 1971
  • 1971-07-14 JP JP46051712A patent/JPS5231668B1/ja active Pending
• 1972
  • 1972-07-03 US US00268451A patent/US3807005A/en not_active Expired - Lifetime

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