Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
• • 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
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/18—Non-metallic particles coated with metal
• • 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
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
  • C22C49/14—Alloys containing metallic or non-metallic fibres or filaments characterised by the fibres or filaments
• • 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
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
  • C22C1/1047—Alloys containing non-metals starting from a melt by mixing and casting liquid metal matrix composites
• • 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
  • Y10T428/12486—Laterally noncoextensive components [e.g., embedded, etc.]

Definitions

• ABSTRACT Composites formed of incompatible constituents, i.e., constituents which are mutua11y insoluble, are produced by introducing at least one such constituent in c oated form into a molten bath of the other, the bath being subjected to the influence of a vortex.
• the present invention is addressed essentially to the same problem but a new and different process has been developed, a process which among other advantages, can be carried forth both more expeditiously and economically, and which in many instances does not require special measures to ensure against oxidation attack.
• the present invention concerns the pyrometallurgical production (melt processing as opposed to powder metallurgy) of composite metallic products (composites) characterized in that at least one constituent thereof (often referred to herein as the dispersoid") is, as a practical matter, insoluble in a second, the latter being metal the percentage of which (by weight) is normally not less than that of any other component of the composite.
• the second constituent can be an alloy or a single element.
• the dispersoid particles may take the form of powders, pellets, fibers, etc., the specific property required and/or the intended application usually being a determining factor.
• powders would be likely used where such qualities as friction, abrasion and wear are important whereas fibers would often be useful where enhanced strength would be the primary objective.
• Powders submicron in size can be utilized although sizes on the order of about 5 or 10 microns or more might be more conducive to ease of handling.
• the coatings encapsulating the dispersoids are advantageously metallic.
• Metals such as nickel, copper, cobalt, iron, aluminum, zinc and various alloys thereof are deemed suitable.
• silicon, tin, molybdenum, chromium, antimony and tungsten are deemed suitable.
• the coating should possess the capability of imparting or contributing to achieving a state of wettability between the incompatible materials sufficient to cause or bring about the dispersion and retention of one in the other. it is considered preferable in using metal coatings that the metal selected not be one capable of readily forming a substantial solid solution with the base material, e.g., nickel in copper.
• the coating should envelop the dispersoid surface as completeiy as possible. Should the overall enclosed surface area be significantly less than what otherwise could be attained, greater can be the expected loss percentagewise of retained (recovered) dispersoid in the incompatible component, a point being ultimately reached at which recovery of the dispersoid is so inferior as to be tantamount to virtual rejection. This is simply another way of stating that poor coatings lead to inferior results.
• coating thickness up to 25 or 50 microns are ordinarily satisfactory.
• the coatings can be provided by well known procedures, including galvanic deposition, deposition from decomposition of carbonyls, e.g., nickel from nickel carbonyl, etc.
• the energy used to generate the vortex should be sufficient to overcome the surface tension at the melt surface such that the vortex is visible. Excessive speeds to the point of turbulence are without benefit and may lead to the loss of material by way of overflow or to undue oxidation of the bath or to the introduction of an undesirable amount of dross in the melt body. On the other hand, unnecessarily low speeds could result in sluggishness of operation with attendant inferior results. For example, although the use of speeds in which a visible vortex is not induced are not excluded from the invention, a greater amount of processing time is more apt to be required and the percentage of retained dispersoid particles might be less.
• rotational speed employed in a given case will somewhat depend upon the nature of the particular materials used in forming a composite, as will be appreciated by those skilled in the art. Generating a vortex in aluminum (light) and lead (heavy) might, though not necessarily, require different speeds due, for example, to viscosity effects. Too, where an impeller is used the diameter thereof will also have an influence upon impeller speed.
• the vortex can be created by other known suitable means, including other mechanical devices or by techniques such as those involving magnetic principles.
• EXAMPLE I A 50 lb. heat of an aluminum-base alloy (nominally containing 9 percent silicon, 3 percent copper and 1 percent magnesium, the balance essentially being aluminum) was melted in an induction furnace fitted with a clay-graphite crucible. The melt was brought to and maintained at a temperature of about 1,350F. and then degassed with nitrogen for approximately 10 minutes. (In commercial practice aluminum and aluminum-base alloys are commonly degassed with nitrogen and this step was for the purpose of simulating commercial processing.)
• a four-bladed impeller was placed in and near the bottom of the bath, the shaft being inclined about degrees from the vertical.
• About 5 lbs. of nickel-coated graphite particles ranging in size from about 100 to 325 mesh (U.S. Series Equivalent) were then dispersed on the melt surface and a visible vortex was induced in the bath by rotating the impeller (driven by an air motor) at approximately 520 revolutions per minute (rpm.).
• the coated particles (each coated particle contained about 50 percent nickel and 50 percent graphite, 2.5 lbs. of graphite being added) were drawn down and into the molten bath within a period of about l minute. The impeller speed was then reduced to rpm. From a visual observation, the vortex had disappeared but no marked rejection of graphite was noted at the surface.
• Example Vll That dispersoids other than graphite can be introduced, dispersed and retained in various molten baths of incompatible base materials is illustrated by Example Vll.
• EXAMPLE VII Using the procedure set forth in Examples Il-Vl, approximately 0.98 percent of silicon carbide was introduced in the form of nickel-coated particles (50 percent nickel by weight) into an aluminum-base alloy melt which nominally contained 12 percent silicon. Subsequent metallographic examination revealed a uniform dispersion of silicon carbide throughout the alloy matrix and analysis showed the presence of about 0.88 percent silicon carbide, a recovery of some 89 percent.
• an advantage of the subject invention is that in using metal coatings the undertaking of special precautionary measures to protect the coatings from atmospheric attack is normally not necessary before being subjected to the influence of the scribed in connection with Example VIII.
• EXAMPLE VIII After forming a molten bath (50 lb.) of a composition set forth in Example I, approximately 5 lbs. of nickel-coated graphite (50 percent graphite) were dispersed on the surface of the melt and permitted to dwell thereon for about 35 minutes at which point the impeller was turned on and the speed raised to 520 rpm., thus generating a visible vortex. After the lapse of about 2 minutes, the impeller speed was reduced to 70 rpm. as in Example I. Again, the once visible vortex disappeared and no marked rejection of graphite was visually detected. Ten permanent mold castings were poured consecutively as in Example I and upon examination each exhibited a pattern of satisfactory graphite distribution, notwithstanding the dwell time of 35 minutes. Three of the castings were analyzed for graphite recovery and the average percentage retained was about 78 percent.
• EXAMPLE IX In a further test performed in much the same manner as in Example VIII, a determination was made that during the dwell period nickel oxide formed. In this test a dwell time of minutes was used; however, samples of the nickel-coated graphite particles were removed at predetermined time intervals of 1 min., 2%, 5 and 15 mins. Temperature was maintained at about 1,350F. Upon X-ray diffraction analysis, a nickel oxide phase was detected as well as nickel and carbon, the intensity of the oxide (ratio of nickel oxide to nickel) increasing with dwell time. (A control example showed only nickel and carbon.) After the 15 min. period, the remaining nickel-coated graphite particles were subjected tothe vortex treatment with good results.
• coated dispersoid particles can remain on the surface of a molten bath for a period at least sufficient for a reaction to take place whereby a substantial portion of the surface of the coating assumes the oxide form but without ultimate detrimental results, is advantageous from a commercial viewpoint. Apart from rendering special measures unnecessary, should an operator unduly delay in generating the vortex once coated particles have been deposited on the melt surface, the operation need not be stopped and scrapped with the possible ineurrence of added expense through loss of material, downtime, etc.
• At least one or more of the constituents constituting the base metal should be capable of reducing the surface of the coating if in oxide form. It is believed that when the oxide is pulled down into the cavity and into the body of molten metal, during the period of suspension therein it is reduced by or reacts with the molten metal such that it transforms back into its native (metallic) state to an extent suffrcient to impart substantial compositional stability between the otherwise incompatible materials. Put another way, it is thought that thevortex operation allows for adequate suspension time to enable the reduction process to take place to a substantial degree.
• a protective atmosphere i.e., a gas blanket, e.g., nitrogen or argon, during the introduction of the coated particles into the bath.
• incompatible systems envisaged as being treatable in accordance herewith, are graphite in copper and copper alloys (e.g., brass and bronze) and lead and tin alloys; silica, alumina and magnesia and other oxides in metals such as copper and nickel; silica, magnesia and others in aluminum; heavy oxides in lead; silicon carbide in nonferrous metals as, for example, zinc or copper as well as aluminum; diamond in aluminum and zinc among others; mica in low melting point metals as zinc, lead, aluminum and magnesium; etc.
• Nitrides and borides as well as carbides and oxides can also serve as the dispersoid.
• molybdenum disulfide is considered a useful dispersoid.
• intermetallic compounds are also contemplated.
• sliding contact elements such as pistons, bearings, sliding valves, cylinder liners and blocks, electrical pickup shoes, all of which can be made from composites of graphite in aluminum and. aluminum alloys.
• Non-skid devices such as tread plates, boat seats, tool handles, boot and shoe soles, nails, etc. are contemplated.
• friction generating devices discs, brakes, brake drums, linings and the like
• friction drive components clutches, conveyor belts, conveyor rolls, gears, mechanisms for toys and projectors, pulleys for belt drives, etc
• machine tool equipment laps, hones, broaches, dies, tools, etc.
• abrasion resistant materials electrical contacts, e.g., for switch gears, pump casings, safes, heat and drill proof items, and grinding wheels.
• a process for producing a solid composite metal product having a metal matrix and at least one constituent distributed therein which is virtually insoluble in a molten bath of the matrix metal which comprises forming a melt of the matrix metal, supplying energy from an external power source to the molten bath such that the molten metal is caused to rotate at a speed sufficient to overcome the surface tension of the melt and to induce therein a visible vortex, subjecting particles of the said insoluble constituent to the rotational action of the vortex, the surfaces of the insoluble constituent particles being substantially encapsulated by a coating possessing the capability of imparting a condition of wettability between the particles and the molten metal, maintaining the vortex until the particles are introduced into and dispersed within the body of the molten bath, and thereafter solidifying at least a portion of the molten metal.
• a process for producing a solid composite metal product composed of at least one dispersoid constituent distributed therein which is virtually insoluble in a molten bath of the metal which comprises forming a melt of the matrix metal, supplying energy to the molten bath such that the molten metal is caused to rotate at a speed sufficient to induce therein a vortex, subjecting particles of the insoluble dispersoid to the action of the rotational effects of the vortex, the surfaces of the particles being substantially encapsulated by a coating possessing the capability of imparting a condition of wettability between the particles and the molten metal, maintaining the vortex such that the particles are drawn into and dispersed within the body of the molten bath, and thereafter solidifying at least a portion of the molten metal.
• a process for producing a solid composite metal product member selected from the group consisting of a sliding contact element, a non-skid device, a friction generating device, a friction drive component and an abrasion resistant article which comprises forming a matrix of molten metal, supplying energy from an external power source to the molten bath such that the bath is caused to rotate at a speed sufficient to overcome the surface tension of the melt and to induce a visible vortex therein, introducing into the molten bath particles of at least one constituent virtually insoluble in the molten metal, the said insoluble constituent particles being subjected to the action of the rotational effects of the'vortex and being further characterized in that they are substantially encapsulated by a metal coating possessing the capability of imparting a condition of wettability between the particles and the molten metal, maintaining the vortex until the particles are introduced into and dispersed within the body of the molten bath, solidifying the molten metal into a composite body and then forming the solid composite into the metal product member desired.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Chemically Coating (AREA)
• Printing Plates And Materials Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=21979427

Family Applications (1)

Country Status (13)

Cited By (14)

Families Citing this family (8)

Citations (9)

• 1970
  • 1970-07-06 US US00052713A patent/US3753694A/en not_active Expired - Lifetime
• 1971
  • 1971-03-23 CA CA108511A patent/CA934167A/en not_active Expired
  • 1971-06-21 ZA ZA714048A patent/ZA714048B/xx unknown
  • 1971-07-01 DE DE19712132665 patent/DE2132665A1/de active Pending
  • 1971-07-05 AU AU30791/71A patent/AU3079171A/en not_active Expired
  • 1971-07-05 AT AT581871A patent/AT311069B/de not_active IP Right Cessation
  • 1971-07-05 CH CH985471A patent/CH537768A/fr not_active IP Right Cessation
  • 1971-07-05 ES ES392902A patent/ES392902A1/es not_active Expired
  • 1971-07-05 FR FR7124517A patent/FR2100260A5/fr not_active Expired
  • 1971-07-06 GB GB3172271A patent/GB1305846A/en not_active Expired
  • 1971-07-06 BE BE769565A patent/BE769565A/xx unknown
  • 1971-07-06 NL NL7109305A patent/NL7109305A/xx unknown
  • 1971-07-06 JP JP4986971A patent/JPS5429442B1/ja active Pending

Patent Citations (9)

Also Published As

Similar Documents