Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C37/00—Manufacture of metal sheets, rods, wire, tubes, profiles or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
  • B21C37/04—Manufacture of metal sheets, rods, wire, tubes, profiles or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of rods or wire
  • B21C37/042—Manufacture of coated wire or rods
• • 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
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
  • B23K20/22—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating taking account of the properties of the materials to be welded
  • B23K20/233—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating taking account of the properties of the materials to be welded without ferrous layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/018—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of a noble metal or a noble metal alloy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
  • H01J19/28—Non-electron-emitting electrodes; Screens
  • H01J19/30—Non-electron-emitting electrodes; Screens characterised by the material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2893/00—Discharge tubes and lamps
  • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
  • H01J2893/0012—Constructional arrangements
  • H01J2893/0019—Chemical composition and manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2893/00—Discharge tubes and lamps
  • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
  • H01J2893/0012—Constructional arrangements
  • H01J2893/0019—Chemical composition and manufacture
  • H01J2893/002—Chemical composition and manufacture chemical
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2893/00—Discharge tubes and lamps
  • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
  • H01J2893/0012—Constructional arrangements
  • H01J2893/0019—Chemical composition and manufacture
  • H01J2893/0022—Manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2893/00—Discharge tubes and lamps
  • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
  • H01J2893/0012—Constructional arrangements
  • H01J2893/0019—Chemical composition and manufacture
  • H01J2893/0022—Manufacture
  • H01J2893/0023—Manufacture carbonising and other surface treatments
• • 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
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12014—All metal or with adjacent metals having metal particles
  • Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
  • Y10T428/12063—Nonparticulate metal component
• • 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
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
  • Y10T428/12826—Group VIB metal-base component
  • Y10T428/12833—Alternative to or next to each other
• • 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
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12875—Platinum group metal-base component

Definitions

• the present invention relates to wire for electron tubes and, more particularly, to iridium-sheathed wire having a core of tungsten or molybdenum.
• the art has endeavored to provide wire suitable for use in high power electron tubes.
• the grid wire which is used in high power electron tubes must have low secondary-emission characteristics and must withstand temperatures up to 1500 C. resulting from electron bombardment. Secondary emission of grid wires is minimized by using materials with low emissivity.
• the platinum layer is capable of keeping the primary grid emission very low, a feature which is of particular importance in transmitting tubes, in which grids often assume a very high tempera ture. With the high power electron tubes now being made, the temperatures reached by the grid wires are such that volatilization of platinum occurs.
• platinum has an appreciable vapor pressure and at temperatures of about 1500 C. and above a platinum-coated grid begins to lose platinum from its surface. Furthermore, in the case of grid wires made of platinum-coated molybdenum or platinum-coated tungsten operating at such elevated temperatures, a platinum-molybdenum or platinum-tungsten alloy which is electronically unsatisfactory is formed on the surface of the grid by diffusion.
• iridium does not diffuse readily into molybdenum or tungsten, and it has a high work function (electron emission energy), good strength at high temperature and a lower vapor pressure than platinum.
• work function electron emission energy
• platinum has not hitherto been possible to produce an iridium-coated molybdenum or tungsten wire. It is notoriously difficult to attempt to deposit iridium by electroplating methods, and iridium is so refractory as to be very diflicult to work mechanically.
• sheathed wire having characteristics which render it highly suitable for use in high power electron tubes, which characteristics include a low work function at the wire surface, low volatilization and good strength at elevated temperatures of at least about 1500 C. and which also include resistance to having the sheath contaminated by diffusion with the core metal and freedom from foreign materials, can be produced by a new process involving powder metallurgy and hot working techniques.
• Another object of the invention is to provide iridiumsheathed wire having a core of tungsten or molybdenum which is free from diffusion between the metal of the sheath and the metal of the core and which is free from foreign substances.
• the present invention is directed to production of iridium-sheathed wire having a core of tungsten or molybdenum without diffusion between the core metal and the iridium and without interposition of any foreign substance between the sheath and the core.
• Wire of the invention is made by hot swaging at about 1450 C. to about 1550 C. and hot drawing at about 500 C. to about 750 C. an assembly which is a filled tube comprising a special iridium tube and a tungsten or molybdenum rod having special characteristics which are correlated to characteristics of the iridium tube.
• the iridium tube is of cylindrical shape with a concentric hole therethrough.
• the rod of core material is sized suitably for making a sliding lit with the hole in the tube.
• the outside and inside diameters of the sintered iridium tube for the assembly are in a ratio from 5:3 to 2:1.
• the swaged and drawn iridium sheath in the wire of the invention is a continuous penetration-resistant sheath that does not have discontinuities such as might be present if a sheath were applied by electroplating.
• the starting metal for the core of wire of the invention is a metal selected from the group consisting of sintered tungsten powder, swaged molybdenum containing up to about 0.5% titanium and swaged and drawn molybdenum containing up to about 0.5% titanium.
• Drawn tungsten is not satisfactory as a starting metal for making wire in accordance with the invention. It is highly advantageous that the metal of the core be characterized by a recrystallization temperature that is higher than the recrystallization temperature of the sheath metal in order that a fibrous structure be developed in the core.
• iridium-sheathed tungsten or molybdenum wire is produced by inserting into a special tube of sintered iridium powder a core that makes a sliding fit in the tube, this core being a sintered rod of tungsten or a swaged or swaged and drawn rod of molybdenum, swaging the filled tube to rod and drawing down the swaged rod.
• the resistances to deformation of the tube and the core be substantially the same.
• the tensile strength of each is within the range of 5000 pounds per square inch (p.s.i.) to 12,000 p.s.i. If the resistances to deformation as shown by the tensile strengths are not substantially the same, excessive stresses are set up in the iridium tube and, as iridium is brittle in the sintered condition, the tube may and probably will fracture.
• the sintered tube of iridium is made by compacting iridium powder and then sintering the compact in air or, preferably, in vacuum.
• a discovery of the invention is that the desired'similar resistances to deformation are obtained by making the sintered density of the iridium from 16 grams per cubic centimeter (gms./
• the sintered density of the tungsten from 14 gms./cm. to 17 gms./cm. It is advantageous that if the sintered density of the iridium is near the lower end of its range, the sintered density of the tungsten should likewise be near the lower end.
• the corresponding hardnesses are from about 220 Vickers Diamond Penetration Number (V.P.N.) to about 310 V.'P.N. for the iridium and about 480 V.P.N. to about 520 V.P.N. for the tungsten.
• Iridium powder' having good sintering properties that is to say, having a surface area of about 0.3 square meters per gram, was compacted around a polished mild steel former under a hydrostatic pressure of 15 long tons per square inch.
• the former having a flange at one end, was surrounded by a latex sheath in which the powder was placed.
• the finished green compact was a tube of iridium of about 4 inches length, of 0.19 inch inside diameter, and of 0.37 inch outside diameter.
• the tub-e was then sintered in vacuum at 1500 C.
• the linear (lengthwise) shrinkage was about 16%, producing a tube having a sintered density of 18 gms./cm. a hardness of about 305 V.P.N., an outside diameter of 0.305 inch and an inside diameter of 0.18 inch.
• a sintered tungsten rod of density of 15 gms./cm. to 16 gms./cm. and not above 17 gms./cm. and having a hardness of about 510 V.P.N. was ground to size to make a sliding fit within the sintered iridium tube.
• the filled tube was swaged at 1500" C. to /s inch diameter rod.
• the swage is one which will produce a smooth finish from fast-acting hammers and with small reductions a symmetrical sheath can be obtained.
• Iridium must be swaged quickly to ensure the metal temperature is high enough during the operation.
• the swaged rod was hot-drawn at 750 C. to 650 C.
• the finished wire had an outside diameter of 0.01 inch, a core diameter of 0.0075 inch, a sheath hardness of 582 V.P.N. and a core hardness of 803 V.P.N.
• the tungsten core When the tungsten core is placed within the iridium tube it can, if desired, be blocked at each end with plugs of iridium, but this is essential only if the heating operation is carried out under oxidizing conditions.
• the sheath will tear unless at about 0.060 inch outside diameter the sheath has a thickness of at least 0.010 inch. As the outside diameter becomes smaller the force required to draw the wire is much reduced and the sheath can then come down in thickness.
• the final wire can be of 0.01 inch diameter, the thickness of the iridium sheath being as low as 0.0005 inch, but usually from 0.001 to 0.002 inch. Thinner sheaths are obtained than would be expected from the initial diameter ratios of the iridium and the tungsten, which are between :3 and 2: 1, because in drawing from 0.03 inch to 0.01 inch diameter the iridium is deformed more than the tungsten.
• molybdenum which as a metal is not as strong as tungsten
• swaged molybdenum rod is used for the core in order to arrive at the essential similarity of resistance to deformation.
• the core metal it is advantageous, in order to produce wire having an iridium sheath of good surface quality, that the molybdenum contain about 0.5% titanium.
• Such an alloy is characterized, among other advantageous characteristics, by a higher recrystallization temperature than pure molybdenum.
• the swaged and drawn condition with a slightly higher hardness (372 V.P.N.) than the swaged condition (337 V.P.N.) is the best starting condition.
• the iridium tube for molybdenum-cored wire is made in exactly the same way as when the core is tungsten.
• the ratio of the outer diameters of the tube and rod is advantageously about 2: 1.
• the rod has a tensile strength between 5000 and 12,000 p.s.i. and its density can be about 10.2 grams per cc.
• An illustrative example of the production of wire having an iridium sheath and a core of an alloy of molybdenum containing about 0.5 titanium in accordance with the invention is as follows.
• a compacted and sintered iridium tube having the same characteristics and dimensions of the tube described in conjunction with the foregoing example of production of iridium-tungsten wire was produced by the same method of the foregoing example, except that the sintered tube of this example had an internal diameter of 0.15 inch.
• a rod of swaged and drawn molybdenum containing 0.5% titanium and having a hardness of about 375 V.P.N. was fitted into the tube, the rod being directed in contact with the iridium surface of the tube.
• the ends of the tube were sealed with iridium plugs to prevent oxidation.
• the filled and sealed tube was hot swaged and hot drawn to a final diameter of 0.012 inch in accordance with the methods employed for making the iridium-tungsten wire of the foregoing example.
• the final diameter of the molybdenum core was 0.005 inch.
• the sheath hardness of the finished wire was 698 V.P.N. and the core hardness was 386 V.P.N.
• the invention is particularly applicable to grid wire for electron tubes, especially for tubes in which the grid becomes as hot as 1500 C. or greater. Since the wire of the invention is essentially free of foreign substances, i.e., substances other than the aforementioned metals of the sheath and core, the wire is especially useful where it is desired to avoid having some such foreign substances in the enclosure within which the wire is used.
• the invention is also generally applicable where wire having oxidation resistance and high strength at elevated temperatures is required and especially where it is desired to have a sheathed wire that has high resistance to diffusion by the core metal.
• a process for making iridium-sheathed wire especially adapted for use as grid wire in a high power electron tube comprising compacting and sintering iridium powder into a tube having outside and inside diameters in a ratio from 5:3 to 2:1, a Vickers Diamond Penetration hardness of 220 to 310 and a sintered density from 16 grams per cubic centimeter to 20 grams per cubic centimeter, providing a rod of metal characterized by tensile strength of 5000 pounds per square inch to 12,000 pounds per square inch and selected from the group consisting of sintered tungsten, swaged molybdenum containing up to about 0.5 titanium and swaged and drawn molybdenum containing up to about 0.5% titanium, fitting said metal rod into said iridium tube to make a filled tube, hot swaging said filled tube at about 1450" C. to about 1550 C and then hot drawing the filled tube at about 500 C. to about 750 C. to wire.

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  • NL NL300785D patent/NL300785A/xx unknown
• 1962
  • 1962-11-26 GB GB44639/62A patent/GB983023A/en not_active Expired
• 1963
  • 1963-11-08 US US322541A patent/US3271849A/en not_active Expired - Lifetime
  • 1963-11-20 DE DEJ24763A patent/DE1195871B/de active Pending
  • 1963-11-26 CH CH1448563A patent/CH411532A/fr unknown

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