Classifications

• • 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
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F2005/001—Cutting tools, earth boring or grinding tool other than table ware
• • 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
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Definitions

• Tungsten carbide for in particular stone, concrete and asphalt cutting
• the invention relates to a hard metal for tools for mechanical processing of, in particular, stone, concrete and asphalt, and to a tool equipped with such a hard metal.
• tungsten carbide-cobalt hard metals with an average WC grain size of approx. 2 to 10 ⁇ m are used for rock, concrete and asphalt cutting.
• the WC medium grain size in hard metals can be determined, for example, by the line cutting method.
• WC hard metals mentioned here can have any combinations and ratios of tungsten and carbon (carbide).
• the entirety of these combinations of tungsten carbide is abbreviated to WC both in the following description and in the claims.
• the hard metal structure between coarse-grained toilet grains contains relatively thick intermediate layers of the co-binder.
• the coercive field strength values of the hard metal indicate how thick the Co intermediate layers are.
• the coercive field strength values of the coarse-grained hard metals are normally in a range up to 17.0 kA / m.
• the carbon content of hard metals should lie approximately in the middle of the two-phase field (without free carbon and ⁇ phase) (H. Suzuki, H. Kubota, "Planseeberichte Pulvermetallurgie", 1966, Vol. 14, 2, Pp. 96-109).
• the concentration of the tungsten in the co-binder of the WC-Co hard metal depends on the carbon content. The tungsten concentration is much higher with a low carbon content.
• the W concentration or the carbon content in a WC-Co hard metal with a specific Co content can be defined by the value of the magnetic saturation.
• the magnetic saturation of a hard metal is defined both as a magnetic moment per unit weight ⁇ (in English “magnetic moment / unit wt.") And as an inductance of saturation per unit weight 4 ⁇ (in English “Saturation induction / unit wt.”) ( B. Roebuck. "Magnetic Moment (Saturation) Measurements on Hardmetals", Int. J. Refr. Met. Hard Mater., 14 (1996) 419).
• the magnetic moment must be multiplied by 4 ⁇ in order to obtain the inductance of the saturation, so that the magnetic moment ⁇ of pure Co is 16.1 ⁇ Tm 3 / kg and the inductance of the saturation 4 ⁇ of pure Co is 201.9 ⁇ TnrVVkg.
• a hard metal for tools for cutting stone, concrete and asphalt is described, for example, in US Pat. No. 4,859,543.
• EP 1 205 569 A2 and EP 1 043 415 A2 relate to hard metals for metal cutting with a low carbon content or low values of magnetic saturation. Both published documents each describe hard metals which contain more than 1% by weight of cubic carbides (TaC, TiC and NbC). The use and the specified minimum amount of these cubic carbides is absolutely necessary for the use of hard metals for metal cutting tools. Hard metals for tools for the construction or mining industry, however, must not contain such significant constituents of Ta, Ti or Nb, since their cubic carbides have a negative effect on the fracture toughness of the WC-Co hard metals. The hard metals used in mining are without exception tungsten carbide-cobalt alloys (H. Kolaska, "Powder Metallurgy of Hard Metals", Hagen, 1992, p.15 / 3).
• US Pat. No. 5,723,177 describes hard metals which contain 3 to 60% by volume of diamond grains with a coating of carbides, nitrides and / or carbonitrides of the chemical elements of groups IV, V and VI of the periodic table. This coating prevents the diamond grains from dissolving directly in the liquid binder during sintering. However, the coating itself is dissolved relatively quickly in the liquid binder.
• the invention has for its object to provide a hard metal or a carbide-tipped tool with improved properties and performance.
• a hard metal having the features of claim 1, claim 6 or claim 13 or a tool according to claim 28.
• the improvement in performance has an effect in particular in the case of hard metals with coercive field strength values of up to 9.5 kA / m, better still up to 8 kA / m, but preferably in the range from 1.6 to 6.4 kA / m.
• the mean WC grain size should preferably be selected from a range from 0.2 ⁇ m to 20 ⁇ m, more preferably from a range from 2 ⁇ m to 20 ⁇ m, and particularly preferably from a range from 4 to 20 ⁇ m.
• the lattice constant of the cobalt in the binder is greater than 1 to 5% greater than that of pure cobalt (0.3545 nm) due to the higher concentration of the tungsten. It has been shown that in order to achieve the preferred properties in hard metals with relatively thin intermediate binder layers or high coercive field strength values of 17 kA / m up to 30 kA / m, the W concentration in the binder must be somewhat higher in order for the binder of such hard metals to be effective is reinforced. This means that, according to the invention, the values of the magnetic saturation of such hard metals are to be selected even lower than the particularly coarse-grained hard metals, namely from the range specified in claim 6.
• the hard metal according to the invention can be further reinforced by embedding nano-particles (particles finer than 100 nm) made of tungsten and cobalt and / or carbon in the co-matrix in the binder.
• nano-particles particles finer than 100 nm
• the flexural strength of such hard metals is up to 30% higher than that of conventional hard metals with a similar WC grain size and the same Co content.
• a hard metal according to the invention containing at least 5% by volume of nano-particles in the binder can preferably contain up to 40% by weight of carbides, nitrides and / or carbonitrides of Ta, Nb, Ti, V, Cr, Mo, B, Zr and / or Hf included.
• the nano-particles preferably also contain Ni, Fe, Ta, Nb, Ti, V, Cr, Mo, Zr and / or Hf.
• the nano-particles which are coherent with the cobalt matrix, stabilize the binder and thus the ones already described Improvements in hard metal properties and a tool provided with them.
• the nano-particles advantageously have a hexagonal or cubic lattice structure, the nano-particles consisting of one or more of the phases C C ⁇ W ⁇ Cz with values X from 1 to 7, Y from 1 to 10 and Z from 0 to 4.
• the nano-particles consist of a phase Co 2 WC. It is also possible that the nano-particles consist of one or more intermetallic phases of tungsten and cobalt and thus contribute to a further improvement of the binder in the sense of the above-mentioned object.
• the binder can also be strengthened if it has fcc-Co and / or hcp-Co in the form of a solid solution of W and / or C in Co.
• the lattice constants of this solid solution are on the order of 1 to 5% larger than those of pure Co.
• the binder can also contain up to 30% by weight of iron.
• the hard metals according to the invention with a low carbon content or high concentration of W in the binder also contain some or all of them round toilet grains, which has a very positive effect on the service life.
• Round toilet bowls are not only circular shapes, but even mostly irregular grain shapes with rounded corners, without sharp facets.
• the hard metals according to the invention with a high W content in the binder, with the inclusion of coated diamond grains can bring about a significant improvement in performance even in the group of ultra-hard hard metal materials, and can be used successfully, since the combination of the high tungsten concentration in the binder with low magnetic saturation leads to a dissolution process of the coating on the Diamond grains significantly suppressed.
• the hard metal has 3 vol.% To 60 vol.% Diamond grains with a coating of carbides, carbonitrides and / or nitrides of Ti, Ta, Nb, W, Co, Mo, V, Zr , Hf and / or Si.
• Figure 1 shows the limit values of magnetic saturation for the range defined in claims 1 and 13.
• Example 1 shows the limit values of magnetic saturation for the range defined in claims 1 and 13.
• a WC-Co hard metal with 6.5% by weight Co and low carbon content was produced.
• the coercive force of this hard metal is 7.0 kA / m
• the flexural strength is 2400 MPa.
• the hard metal contains round WC grains, Co-binder and no ⁇ phase.
• a film-thin sample was prepared for examination by TEM (transmission electron microscopy).
• the W concentration in the binder was measured on the sample using EDX (energy-dispersive X-ray microanalysis).
• the co-lattice constant was determined by TEM and X-ray examinations.
• the W concentration in the binder of the sample is 18 to 19 atom% and the binder contains nano-particles, which are shown in Fig. 2.
• the electron diffractions of the binder show reflections of the tungsten-containing cubic cobalt matrix with fcc structure and the lattice constant of 0.366 nm as well as reflections of the nano-particles in between, which are approx. 3 to 10 nm in size (Fig. 3).
• the largest measurable Dhki value of the nano-particles is 0.215 nm.
• a conventional carbide with 6.5% Co and normal carbon content was produced as a reference.
• the coercive field strength of the reference hard metal is 6.4 kA / m
• hardness HV30 1140
• flexural strength 1950 MPa. Street chisels with cutting elements made of both hard metals were produced and tested on street milling machines. Wear-intensive asphalt was milled, on average 20 cm above the concrete surface, with an average feed of 10 meters per minute. Half of the milling cutter was equipped with the chisels of the new hard metal and the other half with those of the conventional hard metal.
• Fig. 4 shows a comparison of the worn chisels after the field test.
• a WC-Co hard metal with 9.5% by weight Co and low carbon content was produced.
• the coercive field strength is 6.1 kA / m
• hardness HV30 990
• bending strength 2720 MPa.
• the hard metal contains round WC grains, co-binders and no ⁇ phase.
• a conventional carbide with 9.5% Co and normal carbon content was produced as a reference.
• the coercive field strength is 4.3 kA / m
• hardness HV30 1020
• flexural strength 2010 MPa.
• the TEM investigations of the new hard metal show that the W concentration in the binder is 19 to 21 atom% and the binder contains nano-particles.
• the lattice constant of fcc-Co in the binder is 0.368 nm.
• Chisels with cutting elements were made from the two hard metals and tested in the laboratory when cutting abrasive concrete and granite.
• the chisels were also tested in a coal mine when cutting coal / sandstone with a high sandstone content.
• cutting capacities of 700 m concrete up to wear of 1 mm could be achieved, whereas with the chisels with conventional hard metal the cutting performance was only 100 m with the same wear.
• the service life of the chisels when cutting granite with the new hard metal was approx. 2.5 times longer than that of the chisels with conventional hard metal.
• a WC-Co hard metal with 6.5% by weight Co and low carbon content was produced.
• the coercive field strength of this hard metal is 31.2 kA m
• the flexural strength is 2900 MPa
• that Fracture toughness Kic 12.4 MPam 1 2 .
• the W concentration in the binder of the sample is 17 to 18 atom% and the binder contains nano-particles which are embedded in fcc-Co.
• the concentration of the nano-particles in the binder was determined by the line cut method.
• the concentration of the nano-particles is 7.0 ⁇ 0.5% by volume.
• a conventional hard metal without nano-particles with 6.5% Co and normal carbon content was produced.
• the new hard metal clearly has a better combination of hardness, flexural strength and fracture toughness.
• hard metals are preferred in this respect according to the tests carried out, the dhki value of the ordered phases being up to 0.215 nm ⁇ 0.007 nm. Due to the binder described above, the hard metals according to the invention with a coarse-grained structure have an improved combination of bending strength, fracture toughness and wear resistance. Tools with these hard metals have a very high performance in the field of rock and asphalt cutting and, as wearing parts, have a considerably longer service life.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)
• Powder Metallurgy (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (7)

Publications (2)

Family

ID=30118720

Family Applications (1)

Country Status (7)

Families Citing this family (16)

Family Cites Families (2)

• 2003
  • 2003-07-10 DE DE50309106T patent/DE50309106D1/de not_active Revoked
  • 2003-07-10 AU AU2003250024A patent/AU2003250024A1/en not_active Abandoned
  • 2003-07-10 WO PCT/EP2003/007462 patent/WO2004007784A2/fr not_active Ceased
  • 2003-07-10 EP EP03763783A patent/EP1520056B1/fr not_active Revoked
  • 2003-07-10 ES ES03763783T patent/ES2300616T3/es not_active Expired - Lifetime
  • 2003-07-10 US US10/517,661 patent/US20060093859A1/en not_active Abandoned
  • 2003-07-10 AT AT03763783T patent/ATE385262T1/de not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events