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
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/10—Supplying or treating molten metal
  • B22D11/11—Treating the molten metal

Definitions

• the mixing occurs while minimizing the introduction of gas into, and while minimizing the retention of gas within, the mixture of particles and molten metal, and at a temperature at which the particles do not substantially chemically degrade in the molten metal in the time required to complete the step of mixing.
• the composite mixture withdrawn from the mixer is cast by any appropriate technique.
• the composite material made by the method of the invention has a cast microstructure of the metallic matrix, with particulate distributed generally evenly and homogeneously throughout the cast volume.
• the particulate is well bonded to the matrix, since the matrix was made to wet the particulate during fabrication. No significant oxide layer is interposed between the particulate and the metallic matrix.
• the cast composite is particularly suitable for casting and foundry applications where the matrix alloy is a castable composition. For a composite using a wrought alloy matrix, processing is accomplished by known primary forming operations such as rolling and extruding.
• Metal supply means for introducing a flow of molten metal into the mixing means and particle supply means for introducing a flow of particulate into the mixing means are also provided, the metal flow rate of the metal supply means and the particle flow rate of the particle supply means being controllable. Means for removing a flow of mixed composite material from the mixing means is included.
• the apparatus preferably uses one or multiple stages of mixing. If multiple stages are used, they may be accomplished in either one or multiple chambers. In each stage, the molten metal and the particulate are mixed together, as with a dispersing impeller or other technique for achieving sufficient shear of the molten metal with respect to the particulate to wet the metal to the particulate. Care is taken to prevent air or other adversely reacting gas from interfering with the wetting process, although small amounts of beneficial gases may be introduced into the mixer as needed.
• FIGURE 4 is a side sectional view of another mixing apparatus
• FIGURE 5 is a side sectional view of another mixing apparatus
• the mixing process of the present invention minimizes the incorporation of gases into the melt and the retention of adsorbed, dissolved and entrapped gases in the melt, with the result that there is a reduced level of gases in the melt to interfere with wetting of the metal to the particles.
• the mixing process also creates a state of high shear rates and forces between the molten metal and the solid particles in the melt.
• the shear state helps to remove adsorbed gas and gas bubbles from the surface of the particulate by the physical mechanism of scraping and scouring the molten metal against the solid surface, so that contaminants such as gases and oxides are cleaned away.
• the shear also tends to spread the metal onto the surface, so that the applied shear forces help to overcome the forces otherwise preventing spreading of the metal on the solid surface.
• the shearing action does not deform or crack the particles, instead shearing the liquid metal rapidly past the particles.
• a combination of the molten metal and the particles, prior to mixing, is formed by a convenient method.
• the particles may be added to the surface of the melt or below the surface, although in the latter case the particles typically rise to the surface unless mixing is conducted simultaneously to achieve partial or complete wetting.
• the particles can also be added with the pieces of metal before the metal is melted, so that the particles remain with the metal pieces as they are melted to form the melt. This latter procedure is not preferred, as it is desirable to clean the melt prior to addition of the particulate. If the particulate is present during cleaning of the melt, the particulate may be carried to the surface with the cleaning gas.
• the maximum temperature of the metal when in contact with the particles, should not exceed the temperature at which the particles chemically degrade in the molten metal.
• the maximum temperature is dependent upon the type of alloy used, and may be determined for each alloy. While the molten alloy is in contact with the particulate, the maximum temperature should not be exceeded for any significant period of time.
• Molten metal enters near the top of the first chamber 30 from the metal conduit 20.
• the particulate is introduced onto or just under the surface of the metal through the conduit 26.
• the first chamber 30 contains a vertically mounted impeller 36 generally of the type shown in Figure 2, which enters the chamber 30 through a rotational vacuum fitting 38 and is driven by an external variable speed motor 40.
• the impeller 36 stirs the particulate into the molten metal, to form the first form of the composite material. Care is taken that gas is not introduced into the molten material, as through a vortex produced by the impeller 36. Wetting of the molten metal to the particulate is achieved by the high shear mixing action.
• the apparatus of Figure 3 has a two-stage mixer wherein both stages use impeller mixing.
• Other types of apparatus are possible, and one such alternative embodiment is illustrated in Figure 4.
• the molten metal supply 14, particulate feeder 16, and holding furnace 18 are as previously described.
• the molten metal and the particulate are introduced into an essentially straight cylindrical mixer 62 whose cylindrical axis is horizontal.
• the wall 64 of the mixer 62 is formed of a nonconducting material such as aluminum oxide.
• a high frequency induction coil 66 is wound around the exterior of the cylindrical mixer 62. The induction coil 66, when operated, mixes the molten metal and particulate that is flowing from left to right in the view of Figure 4, to produce the composite material.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Pile Receivers (AREA)

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Publications (2)

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Country Status (7)

Cited By (1)

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Family Cites Families (4)

• 1992
  • 1992-03-04 EP EP92906047A patent/EP0575397B1/de not_active Expired - Lifetime
  • 1992-03-04 AU AU13335/92A patent/AU1333592A/en not_active Abandoned
  • 1992-03-04 WO PCT/CA1992/000095 patent/WO1992015412A1/en active IP Right Grant
  • 1992-03-04 AT AT92906047T patent/ATE161760T1/de not_active IP Right Cessation
  • 1992-03-04 JP JP04505906A patent/JP3096064B2/ja not_active Expired - Fee Related
  • 1992-03-04 DE DE69223950T patent/DE69223950T2/de not_active Expired - Fee Related
• 1993
  • 1993-09-10 NO NO933243A patent/NO303722B1/no not_active IP Right Cessation

Non-Patent Citations (1)

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