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
  • C22C1/0425—Copper-based alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
  • C22C32/0084—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ carbon or graphite as the main non-metallic constituent
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/02—Parts of sliding-contact bearings
  • F16C33/04—Brasses; Bushes; Linings
  • F16C33/06—Sliding surface mainly made of metal
  • F16C33/12—Structural composition; Use of special materials or surface treatments, e.g. for rust-proofing
  • F16C33/121—Use of special materials

Definitions

• This invention is directed to a novel mixture of elemental powders for producing sintered nickel-bronze articles from compacts having a low dimensional sensitivity to variations in sintering temperature.
• the sintering temperature employed is sufficiently high to cause the tin to melt and thereafter dilfuse rapidly into the still solid copper constituent to form the desired bronze.
• the powder mixture most commonly used contains approximately 90% copper and 10% tin and is dimensionally highly sensitive to changes in the temperature and time employed for sintering.
• the sintering furnace temperature will vary somewhat from time to time within the normal tolerance of the furnace temperature controls and through erroneous settings and from other causes. Aside from such variations in average furnace temperature, there may be local overheating or underheating due to such factors as placement of heating elements and location and volume of the furnace charge.
• the desired characteristics are obtained using a mixture of the powder constituents tin, nickel, graphite and copper in a relatively narrow and critical range of composition.
• This range of composition is, by weight, from 7% to 8% tin, from 4.5% to 5.5% nickel, from 0.25% to 4% graphite, and the balance essentially copper with small amounts of incidental impurities.
• An optimized mixture composition for the elemental powders within the above-defined range contains, by weight, about 7.5% tin, about 5% nickel, about 1% graphite and the balance essentially copper except for small amounts of incidental impurities.
• the copper constituent of the powder employed in making the compacts of the invention may be in the form of a powder substantially all of which will pass through a 100 mesh (British Standard Screen) sieve.
• the tin constituent is preferably in the form of a powder substantially all of which will pass through a 300 mesh (B.S.S.) sieve.
• the nickel constituent is preferably added in the form of fine carbonyl nickel powder (average particle size 9 microns).
• the graphite constituent may Ibe added as a fine powder that will pass through a 300 mesh B.S.S. sieve.
• the powder mixture may contain pore-forming agents or die lubricants or both, for example, a metallic stearate such as zinc stearate or paraffin wax.
• the constituent powders are first thoroughly mixed and tumbled for 2 hours in a double cone mixer.
• the powders are then formed into hearings or other articles by the usual process of pressing, sintering and sizing or coining, and the invention includes such sintered articles.
• Green compacts were made employing the optimized powder mixture composition of, by weight, 7.5 tin, 5% nickel, 1% graphite and the balance copper except for small amounts of incidental impurities.
• approximately grams of the mixed powder were pressed at 8 tons per square inch in a 1" diameter steel die. This compaction step yields green compacts with final densities of 5.8 to 6.2 grams per cubic centimeter. The green compacts were 1" in diameter and approximately 1" high.
• the compacts were sintered at temperatures of 760 C., 780 C., 800 C., or 830 C. for times of 15, 30, 45 or 60 minutes in a cracked ammonia atmosphere.
• the sintering time was measured as the time at the given temperature after an initial heating period of 15 minutes to bring the compact to the sintering temperature. Cooling was accomplished in a water-jacketed cold zone of the furnace.
• Table I the value for dimensional change during sintering was determined along a diameter of the cylinder of two compacts sintered at each temperature, and the mean of the two values was taken.
• the percentages of nickel and tin are specifically set forth; it being understood that the mix- :ure contained 1% graphite, and 0.75% zinc stearate with :he balance copper and impurities.
• composition according to the invention is also relatively insensitive to sintering time, though this is of lesser significance under commercial conditions, since the sintering time can be more readily controlled.
• the dimen- 4 sional changes of compacts of Mixture A after sintering for diiferent times at 800 C. are set forth in Table III.
• a method for making sintered nickel-bronze alloy members by powder metallurgy techniques which comprises pressing the constituent powders to produce green compacts of predetermined configuration and thereafter sintering the green compacts to produce a1- loy members from the compacted constituent powders in the predetermined configuration
• the improvement comprising controlling the composition of the constituent powders from which the green compacts are made to a relatively restricted range to minimize the dimensional sensitivity of the compacts to variations in the sintering temperature, the constituent powders consisting of, by weight, from 7% to 8% tin, from 4.5% to 5.5% nickel, from 0.25% to 4% graphite and the balance essentially copper except for small amounts of incidental impurities and exhibiting low dimensional sensitivity to variations in sintering temperature over the temperature range 760 C. to 830 C.
• constituent powders consist of, by weight, about 7.5% tin, about 5% nickel, about 1% graphite and the balance essentially copper except for small amounts of incidental impurities.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10054708

Family Applications (1)

Country Status (6)

Cited By (3)

Families Citing this family (3)

Citations (4)

• 1967
  • 1967-04-03 GB GB05195/67A patent/GB1162573A/en not_active Expired
• 1968
  • 1968-03-08 US US711513A patent/US3453103A/en not_active Expired - Lifetime
  • 1968-03-28 AT AT306668A patent/AT281438B/de not_active IP Right Cessation
  • 1968-03-29 NL NL6804497A patent/NL6804497A/xx unknown
  • 1968-04-02 FR FR1565007D patent/FR1565007A/fr not_active Expired
  • 1968-04-03 BE BE713156D patent/BE713156A/xx unknown

Patent Citations (4)

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