Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
  • B02C15/004—Shape or construction of rollers or balls
  • B02C15/005—Rollers or balls of composite construction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C13/00—Disintegrating by mills having rotary beater elements ; Hammer mills
  • B02C13/26—Details
  • B02C13/28—Shape or construction of beater elements
• • 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
  • B22D19/02—Casting in, on, or around objects which form part of the product for making reinforced articles
• • 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
  • B22D19/06—Casting in, on, or around objects which form part of the product for manufacturing or repairing tools
• • 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
  • B22D19/08—Casting in, on, or around objects which form part of the product for building-up linings or coverings, e.g. of anti-frictional metal

Definitions

• the present invention relates to a composite wear part produced by casting and made up of a metal matrix, the wear surface has inserts with good resistance to wear.
• the invention relates in particular to wearing parts used in crushing, crushing and transport facilities various abrasive materials found in industries such as cement plants, mines, metallurgy, power plants or various careers. These parts are often subjected to high mechanical stresses in the mass and high wear by abrasion to their working surface. It is therefore desirable that these parts have a high resistance to abrasion and a certain ductility to be able to withstand mechanical stresses such as shocks and to possibly be machined.
• the ceramic cake can be formed in pouring into a suitable mold grains of ceramic material and then a liquid glue with good fluidity, for example a resin liquid which, after hardening, retains the grains to form the ceramic structure.
• a liquid glue with good fluidity for example a resin liquid which, after hardening, retains the grains to form the ceramic structure.
• the ceramic material can be made aluminum oxide or zirconium oxide.
• This known technique is however limited to the molding of precision of relatively small parts and where compatibility between the metal matrix and the ceramic structure, especially in terms of thermal behavior, hardly poses any problems since when casting metal the mold and the ceramic structure are preheated and the part does not undergo subsequent heat treatment.
• the technique is, moreover, limited to the production of specific parts with specific requirements determined for hardness and toughness, as well as for parts sold at a very high price because the lost wax molding process is itself very expensive.
• the object of the present invention is to provide a wearing part composite with ceramic inserts meeting, so satisfies the requirements listed above.
• the invention provides a composite wear part produced by conventional or centrifugal casting and consisting of a metal matrix, the wear surface of which includes inserts having good wear resistance, characterized in that the inserts are ceramic parts, themselves composite, consisting of 20 to 80% of Al 2 O 3 and 80 to 20% of ZrO 2 , the percentages being expressed by weight of the constituents.
• the inserts may, in addition, contain other oxides, the proportion by weight does not exceed 3 to 4%.
• the inserts consist of an agglomerate of ceramic grains composites preferably having a particle size included in the range F6 to F20 of the FEPA standard, i.e. a diameter included between approximately 1.5 mm and 5.5 mm. These grains can be made by electrofusion, sintering, thermal spraying or any other process merging the two constituents.
• the invention is based on the observation that aluminum oxide (corundum) and zirconium oxide have different properties, which allows, by a judicious choice in the aforementioned ranges, to adjust the hardness, toughness and the coefficient of thermal expansion of the ceramic composite so as to obtain good hardness and good toughness and to make it compatible with the precise application for which the part is intended, on the one hand, and to obtain, on the other hand, a coefficient of expansion of the ceramic composite which is close to that of the chosen casting metal, that is to say of cast iron or steel having a coefficient of expansion of between 10.10 -6 and 11.10 -6 .
• Zirconium oxide has the advantage of having a coefficient of expansion which is close to that of metal. In addition, it contributes to good toughness, that is to say it reduces the risk of breakage.
• Aluminum oxide on the other hand, contributes to good hardness. These composirts are known to have good toughness.
• the zirconia particles present in alumina make it possible, by well-known mechanisms, to increase the resistance to cracking of the latter and thus to obtain a toughness greater than that of each component considered in isolation, namely ZrO 2 or Al 2 O 3 .
• the choice of the proportions of the constituents of the ceramic insert composite can, of course, also take into account the composition of the casting metal in view of the properties required the application for which the part is intended. Similarly, the choice of composition of the casting metal can be adapted to the nature of the composite insert.
• Example 1 manufacture of an axis crusher ejector vertical.
• a mixture of 75% Al 2 O 3 and 25% ZrO 2 is formed, the two constituents of which are fused by electrofusion to form grains with a particle size included in categories F6 to F20 of the FEPA standard. These grains are then poured into a mold of suitable shape with a liquid resin which, after hardening, retains the grains together to form the ceramic wafer which must constitute the insert of the wear part. These inserts are placed in a suitable mold into which a liquid metal is poured comprising 3% carbon, 26% chromium and other traditional elements in small proportion which are always encountered in alloys of this type. A wear part is thus produced with ceramic inserts with a hardness of the order of 1600 Hv with a coefficient of expansion close to 8.10 -6 , maintained in a cast iron matrix with a hardness close to 750 Hv.
• Example 2 manufacture of a crusher rotor.
• An insert is prepared as in Example 1 but by choosing, this time, a ceramic composition which favors the coefficient of expansion at the expense of hardness, more precisely 40% of ZrO 2 and 60% of Al 2 O 3 . This produces an insert with a hardness of around 1,350 Hv with a coefficient of expansion close to 9.10 -6 .
• the goal here is to reduce the risk of cracks in the room because of the high impact level to which this type of part is subjected.
• the metallic matrix will consist of a manganese steel with a composition of 1% carbon, 14% manganese and 1.5% molybdenum.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Food Science & Technology (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Compositions Of Oxide Ceramics (AREA)

Priority Applications (28)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8224453

Family Applications (1)

Country Status (2)

Cited By (9)

Citations (7)

• 1996
  • 1996-10-01 EP EP96202741A patent/EP0838288A1/de not_active Withdrawn
• 1997
  • 1997-09-26 ZA ZA978672A patent/ZA978672B/xx unknown

Patent Citations (7)

Non-Patent Citations (4)

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