Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B29/00—Layered products comprising a layer of paper or cardboard
• • 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
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
  • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
  • B23B27/148—Composition of the cutting inserts
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
  • C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide
• • 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
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
• • 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
  • Y10T428/12014—All metal or with adjacent metals having metal particles
  • Y10T428/12021—All metal or with adjacent metals having metal particles having composition or density gradient or differential porosity

Definitions

• the present invention relates to cemented carbide bodies preferably used in tools for drilling/cutting of rock and mineral. Also cemented carbide tools used for asphalt and concrete are included. More specifically, the invention pertains to cemented carbide tools made via sintering techniques wherein there are two distinct microstructural zones having complementary properties.
• the grain size, as well as the binder phase (e.g., cobalt) content each has an influence on the performance of the composite. For example, a smaller/finer grain size of the tungsten carbide results in a more wear resistant material. An increase in cobalt content typically leads to an increase in toughness. Cemented carbides having a fine grain size are produced through the incorporation of grain refiners in the initial powder blend.
• Such cemented carbide has a fine grain size throughout its microstructure .
• Cemented carbide with a coarse grain size is produced via sintering without the incorporation of any grain refiners since the tendency of a cemented carbide like a WC-Co composite is for the WC grains to coarsen during sintering.
• Such cemented carbide has a coarse grain size throughout its microstructure.
• these hard bodies have a uniform microstructure throughout the cemented carbide body.
• Cemented carbide bodies having at least two distinct microstructural zones are known in the art. For example drills having a core of a tough cemented carbide grade and a cover of a more wear resistant grade are disclosed in EP-A-951576.
• EP-A-194018 relates to a wire drawing die made from a central layer with coarse grained tungsten carbide particles and a peripheral layer with finer grained tungsten carbide particles. Initially the layers have the same content of cobalt. After sintering the coarse grained layer in the center is reduced in cobalt content.
• EP-A-257869 discloses a rock bit button made with a wear resistant tip portion and a tough core. The tip portion is made from a powder with low Co-content and a fine WC grain size and the core portion is made from a powder with high Co content and coarse WC grains. None is disclosed about the Co-content in the two portions after sintering.
• US 5,623,723 discloses a method of making a cemented carbide body with a wear resistant surface zone.
• the method includes the following steps: providing a compact of cemented carbide; placing a powder of grain refiner on at least one portion of the exposed surface of the compact; and heat treating the compact and grain refiner powder so as to diffuse the grain refiner toward the center of the green compact thereby forming a surface zone inwardly from the exposed surface in which the grain refiner was placed, and forming an interior zone.
• a cemented carbide body is obtained with a surface zone having a grain size that is smaller but with a Co-content that is higher than that of the interior portion of the body.
• Fig 1 is a graph showing hardness (HV3) and cobalt content (WDS-analysis) versus distance from the surface where the grain refiner powder was placed on a button for mining application according to the invention.
• Fig 2 is a graph showing chromium content (WDS-analysis) versus distance from the surface where the grain refiner powder was placed on a button according to the invention.
• Fig 3a is a micrograph showing the microstructure at a distance of 20 ⁇ m from the surface where the grain refiner powder was placed (FEG-SEM, 2000X, BSE mode) on a button according to the invention.
• Fig 3b is a micrograph showing the microstructure at a distance of 2.5 mm from the surface where the grain refiner powder was placed (FEG-SEM, 2000X, BSE mode) in a button according to the invention.
• Fig 3c is a micrograph showing the microstructure in the interior portion (center) of the button (FEG-SEM, 2000X, BSE mode) according to the invention.
• a cemented carbide tool insert/button for mining and construction applications comprising at least one surface portion, the surface zone poor in binder has a width of 0.05-0.9 of the diameter/width of the cemented carbide body, preferably 0.1-0.5, most preferably 0.15-0.4 and the grain size is smaller than in the interior portion and the Co-content is lower than that in the interior portion resulting in compressive stresses at the surface after sintering. More particularly the Co-content of the surface portion is ⁇ 1, preferably- ⁇ 0.9, most preferably ⁇ 0.75 of the Co-content in the interior portion and the WC grain size of the surface zone is ⁇ 1, preferably ⁇ 0.9, most preferably ⁇ 0.8 of the WC grain size in the interior portion.
• the composition of the cemented carbide is WC+Co with a nominal Co-content of 4-25 wt-%, preferably 5-10 wt-% and a nominal WC grain size, arithmetic mean of intercept, of 1-15 ⁇ m, preferably 1.5-5 ⁇ m. In one embodiment the cemented carbide contains ⁇ -phase.
• the present invention also relates to a method of making a cemented carbide body with a wear resistant surface zone including the following steps: - providing a compact of cemented carbide made from a single powder comprising powders forming hard constituents and binder phase of Co and/or Ni; - possibly grind the compact to desired shape and size; - placing a powder of grain refiner containing on at least one portion of the exposed surface of the compact by dipping, spraying, painting applying a thin tape or in any other way, preferably being any chromium carbide (Cr3C2, Cr23Cg and Cr C3 or mixtures of these) or a mixture of chromium and carbon or other compounds containing chromium and carbon and/or nitrogen; - sintering the compact and grain refiner powder so as to diffuse the grain refiner away from the surface (s) of grain refiner application thereby forming a gradient zone characterised of low binder phase content
• the nominal carbon content of the cemented carbide compact shall be determined by consideration of the carbon contribution from the applied grain refiner. Also compacts that would result in a eta-phase containing microstructure can be used.
• the sintering shall be performed for shortest possible time to obtain the desired structure and a body with closed porosity, preferably a dense body. This time depends on the grain size of WC and the composition of the cemented carbide and can therefore not be closer defined. It is within the purview of the person skilled in the art to determine whether the requisite structure has been obtained and to modify the sintering conditions m accordance with the present specification. If necessary the body can be post-HIP- ed at a lower HIP—temperature compared to the sintering temperature and at a pressure of 2-100 MPa. Alternatively, the gram refiner/chromium carbide powder is placed on a pre-smtered body that is subsequently heat treated to obtain the desired structure at a temperature higher than the temperature for pre-sintering.
• Example 1 Cemented carbide compacts were made according to the following: Cylindrical green compacts were pressed (diameter 12mm) from a powder with the composition of 94 weight-% WC and 6 weight- % Co. The WC raw material was relative coarse-grained with an average grain size of 3.0 ⁇ m (FSSS) . All surfaces were covered with a Cr3C2 containing thin layer (0.02 g Cr3C2/cm 2 ) . Thereafter the compacts were sintered at 1350°C for 30 minutes. During the last 15 minutes of the sintering an isostatic gas pressure of 10 MPa was applied to obtain a dense body. A cross-section of the sintered button was examined. No Cr3C2 could be seen on the surface.
• Figure 1 shows a graph of hardness and cobalt content versus the distance to the previously Cr3C2 ⁇ covered surface.
• the cobalt content is lowest close to the surface and increases with increasing distance to a max value and then decreases again.
• the hardness is highest close to the surface and decreases with the distance to a mm value and then increases again towards the center.
• Figure 2 shows a graph of chromium content versus the distance to the previously Cr3C2 ⁇ covered surface. The chromium content is highest close to the surface and decreases with the distance.
• Figure 3a is a micrograph showing the microstructure at a distance of 20 ⁇ m from the previously Cr3C2-covered surface (FEG-SEM, 2000X, BSE mode) .
• Figure 3b is a micrograph showing the microstructure at a distance of 2.5 mm from the previously Cr3C2- covered surface (FEG-SEM, 2000X, BSE mode) .
• Figure 3c is a micrograph showing the microstructure the interior portion (6 mm from the previously Cr3C2 ⁇ covered surface) of the button (FEG- SEM, 2000X, BSE mode) .
• the WC-grain sizes measured as arithmetic mean of intercept values are presented m table 1. Table 1 .

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Manufacturing & Machinery (AREA)
• Powder Metallurgy (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)

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• 2004
  • 2004-12-07 AU AU2004297495A patent/AU2004297495B2/en not_active Expired
  • 2004-12-07 WO PCT/SE2004/001817 patent/WO2005056854A1/en not_active Ceased
  • 2004-12-07 RU RU2006125430/02A patent/RU2364700C2/ru active
  • 2004-12-07 CA CA2547926A patent/CA2547926C/en not_active Expired - Lifetime
  • 2004-12-07 KR KR1020067012399A patent/KR101387183B1/ko not_active Expired - Lifetime
  • 2004-12-07 JP JP2006545279A patent/JP5448300B2/ja not_active Expired - Lifetime
  • 2004-12-07 EP EP04801724.8A patent/EP1697551B1/en not_active Expired - Lifetime
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• 2008
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• 2012
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