Classifications

• • 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
  • C22C1/0466—Alloys based on noble metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C9/00—Cooling, heating or lubricating drawing material
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/14—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of noble metals or alloys based thereon
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S72/00—Metal deforming
  • Y10S72/70—Deforming specified alloys or uncommon metal or bimetallic work

Definitions

• the present invention relates to the art of wire drawing and more particularly to processes for drawing wire made of ruthenium or ruthenium-rich alloys.
• the refractory metal ruthenium is normally produced as a powder by the reduction of a salt or compound of the element.
• the powder is preferably compacted and sintered by conventional powder-metallurgical techniques.
• the resultant metal is usually difiicult to work and the workability can be improved by alloying it with from 0.1%, or 0.25%, to 25% rhenium by powder-metallurgical methods, e.g., as described in U.S. Pat. No. 3,362,799.
• Ruthenium or a ruthenium-rich alloy is sometimes required as wire, e.g., for spark plug electrodes and thermocouples. Hitherto this has been produced by hot-drawing the metal or alloy through a die made of tungsten carbide in a cobalt or similar matrix or of other sintered hard metal, which is heated to as high a temperature as is practicable, e.g., to about 1200 C.
• Such processes however have the great disadvantages that only a very small reduction can be effected in each pass, the surface rfinish of the wire is poor due to breakdown of the lubricant, the wear on the die is very great and the yield of satisfactory material is low. Insofar as We are aware there was not heretofore known any process for drawing ruthenium wire that was entirely successful when carried into practice commercially on an industrial scale.
• the present invention contemplates a process comprising drawing a ruthenium-rich metal, which can be commercially pure ruthenium or a ruthenium alloy containing at least 90% ruthenium, through a die of hard metal that is maintained at a temperature of 900 C. to 1050 C. Below 900 C., the temperature of the die is too low and the wire splinters, thus giving an undesirable surface. Above 1050 C. the wear on the throat of the die is excessive and the finished size of the wire is very difficult, if not impossible, to control.
• the present invention involves the discovery that ruthenium is more readily hot drawn to wire when the temperature of the drawing die is relatively low and is controlled within narrow limits of 900 C. to 1050 C., advantageously 950 C.
• the ruthenium which is usually in the form of rod, is preheated to a temperature of about 1000 C. to about 1300 C., advantageously within the range of 1150" C. to 1250 C.
• This preheating may be done in an electric-resistance furnace and is advantageously done in a nonoxidizing atmosphere, such as an inert or reducing gas.
• the hot die can be substantially enclosed in a small electric-resistance tube furnace containing an inert or reducing, and thus nonoxidizing, atmosphere, e.g., an atmosphere of hydrogen. It is essential to lubricate the wire and it is advantageous to use graphite for the lubricant in the present process.
• any hot drawing lubricant that is not harmful to ruthenium will usually suffice. It is highly de sirable to prevent oxidation of the wire when it emerges from the die and it is also advantageous to chill the wire at this stage to obtain adequate strength in the wire at that zone in order to enable the drawing force to be maintained without breaking the wire.
• These objects of preventing undue oxidation and obtaining adequate strength can be accomplished simultaneously by quenching the emerging wire with a water jet, which ensures that it falls to a temperature at which oxidation will not take place and which also provides a blanket of steam around the die outlet and so assists in preventing oxidation.
• the water jet should be as close to the die as possible without impinging directly upon it. It will, of course, be understood that other harmless quenching fluids that are volatilizable into a protective atmosphere can also be employed for these purposes.
• Alloys of ruthenium which are processed in accordance with the invention include ruthenium powder metallurgical alloys containing 0.1% or 0.25% or more rhenium, e.g., 2% rhenium.
• rhenium content is controlled to amounts not greater than about 10%, e.g., 0.1% to 10% rhenium. All alloy composition percentages set forth herein are by weight.
• Ruthenium-rhenium alloy products, e.g., rods, that are suitable as wire drawing stock for the process of the invention can be produced by the method described in Us. Pat. No. 3,362,799.
• the ruthenium-rich metals drawn in the process of the invention contain at least about ruthenium.
• Wire-drawing dies for the present process are of heatresistant hard metal, e.g., sintered metals such as cobaltbonded tungsten carbide. Another satisfactory metal for the dies is chromium carbide. It is to be understood that any other hard metal carbide of sufficient wear resistance may also be used and that certain ceramic dies such as those of alumina or similar ceramics may offer advantages.
• EXAMPLE I Commercially pure ruthenium powder containing at least about 99.9% ruthenium and very small amounts of impurities, e.g., 0.001% palladium, 0.03% osmium, 0.01% iron, 0.002% nickel, and of particle sizes passing through a 200 British Standard Screen (BSS) mesh sieve was pressed isostatically in a flexible bag at a pressure of 25 long tons (2240 pounds) per square inch. This pressing produced a right cylindrical. compact of 3-inches length and 0.5-inch diameter. The thus-produced compact was sintered at 1450 C. for 8 hours in vacuo to form a right cylindrical ingot. The sintered ingot was swaged at 1500 C.
• impurities e.g., 0.001% palladium, 0.03% osmium, 0.01% iron, 0.002% nickel, and of particle sizes passing through a 200 British Standard Screen (BSS) mesh sieve was pressed isostatically in a flexible bag at a pressure of 25 long tons (2
• the wire was flash-annealed in an induction In contrast to the good surface finish results obtained furnace in an atmosphere of hydrogen and 90% 10 with Examples 1 through 7, detrimental splintering on the nitrogen for 10 seconds at 1800 C.
• the Wire Surface was encountered when swaged and centerless wire was lubricated by an aqueous suspension of graphite. ground rod of an alloy containing 2% rhenium and bal- When thus drawn to 0.046-inch diameter the ruthenium ance ruthenium was preheated to 1200 C. and drawn wire produced in this example of the invention was of with the die at a temperature of 800 C. (which die temgood quality with a highly satisfactory surface finish.
• Metal-Ru-2% Re refers to alloy of 2% rhenium and balance ruthenium.
• Rod stock dia.-Diameter of red at start of drawing.
• Anneal H.T.AAnnealing heat treatment during wire drawing, of flash annealing by induction heating to about 1,800 C. for 5 to 10 seconds in a nitrogen-10% hydrogen atmosphere.
• Anneal HEB-Annealing heat treatment during wire drawing, by holding in a resistance furnace at 1,500 C. in a hydrogen atmosphere.
• the wire was preheated to 1200 C. and drawn through tungsten carbide dies that were heated to 950 C.
• powders of the metals to be drawn were consolidated by compaction and sintering and the sintered compacts were then worked to rod by forging and swaging.
• the swaged rods were centerless ground, generally reducing the diameter about 0.02 inch, and were then annealed using the same heat treatment that was to be applied for intermediate annealing, if any.
• Drawing lubrication was applied with semicolloidal graphite layers that were baked onto the rods or wires before each pass.
• the bore of the die was impregnated with graphite lubricant.
• the wire was drawn at a speed of about 30 inches per minute with the die in a resistance furnace wherein a hydrogen atmosphere was maintained.
• a water jet was directed onto the hot wire where it emerged from the furnace so as to quench the Wire below red heat and provide a steam atmosphere to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand.
• Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.
• a process of hot drawing a ruthenium-rich metal containing at least about ruthenium through a hard metal die comprising preheating said ruthenium-rich metal to a temperature of about 1000 C. to about 1300 C. in a nonoxidizing atmosphere and, while protecting said preheated ruthenium-rich metal from oxidation, drawing the hot ruthenium-rich metal through the wire drawing die at a die temperature of 900 C. to 1050 C.
• a process as set forth in claim 1 comprising, at about the time the wire emerges from the die, chilling 5 6 the drawn wire and simultaneously providing a nonoxidiz- References Cited ing atmosphere around the emerging wire.
• UNITED STATES PATENTS 4 A process as set forth in claim 1 comprising directing a water jet onto the wire at about the time the wire 3,124,657 7/1965 J nes at al. l 148-11.5 X emerges f the r ,3 2,799 1/1968 Betterl ge et a 75172 X 5.
• a process as set forth in claim 1 wherein the rutheni- 0 um-rich metal is commercially pure ruthenium.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Metal Extraction Processes (AREA)

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Publications (1)

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Cited By (12)

Citations (2)

• 1967
  • 1967-07-10 GB GB31676/67A patent/GB1162750A/en not_active Expired
• 1968
  • 1968-06-19 US US738126A patent/US3528862A/en not_active Expired - Lifetime
  • 1968-07-05 DE DE19681752717 patent/DE1752717A1/de active Pending
  • 1968-07-09 FR FR1579693D patent/FR1579693A/fr not_active Expired
  • 1968-07-09 NL NL6809657A patent/NL6809657A/xx unknown
  • 1968-07-10 BE BE717885D patent/BE717885A/xx unknown

Patent Citations (2)

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