CA3114969A1 - Hard metal having toughness-increasing microstructure - Google Patents
Hard metal having toughness-increasing microstructure Download PDFInfo
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- CA3114969A1 CA3114969A1 CA3114969A CA3114969A CA3114969A1 CA 3114969 A1 CA3114969 A1 CA 3114969A1 CA 3114969 A CA3114969 A CA 3114969A CA 3114969 A CA3114969 A CA 3114969A CA 3114969 A1 CA3114969 A1 CA 3114969A1
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- Prior art keywords
- carbide
- cemented carbide
- phase
- cemented
- metal
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 77
- 239000002184 metal Substances 0.000 title claims abstract description 77
- 239000011230 binding agent Substances 0.000 claims abstract description 28
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000013078 crystal Substances 0.000 claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000000843 powder Substances 0.000 claims description 38
- 239000000203 mixture Substances 0.000 claims description 27
- 150000001247 metal acetylides Chemical class 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 19
- 229910003468 tantalcarbide Inorganic materials 0.000 claims description 17
- 239000002245 particle Substances 0.000 claims description 16
- 229910003470 tongbaite Inorganic materials 0.000 claims description 14
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 9
- 239000010941 cobalt Substances 0.000 claims description 8
- 229910017052 cobalt Inorganic materials 0.000 claims description 8
- 239000007858 starting material Substances 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 150000001875 compounds Chemical class 0.000 claims description 5
- 239000003966 growth inhibitor Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- UNASZPQZIFZUSI-UHFFFAOYSA-N methylidyneniobium Chemical compound [Nb]#C UNASZPQZIFZUSI-UHFFFAOYSA-N 0.000 claims description 5
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 238000005245 sintering Methods 0.000 claims description 5
- 238000009826 distribution Methods 0.000 claims description 4
- INZDTEICWPZYJM-UHFFFAOYSA-N 1-(chloromethyl)-4-[4-(chloromethyl)phenyl]benzene Chemical compound C1=CC(CCl)=CC=C1C1=CC=C(CCl)C=C1 INZDTEICWPZYJM-UHFFFAOYSA-N 0.000 claims description 3
- UFGZSIPAQKLCGR-UHFFFAOYSA-N chromium carbide Chemical compound [Cr]#C[Cr]C#[Cr] UFGZSIPAQKLCGR-UHFFFAOYSA-N 0.000 claims description 3
- WHJFNYXPKGDKBB-UHFFFAOYSA-N hafnium;methane Chemical compound C.[Hf] WHJFNYXPKGDKBB-UHFFFAOYSA-N 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 229910026551 ZrC Inorganic materials 0.000 claims description 2
- OTCHGXYCWNXDOA-UHFFFAOYSA-N [C].[Zr] Chemical compound [C].[Zr] OTCHGXYCWNXDOA-UHFFFAOYSA-N 0.000 claims description 2
- 238000004458 analytical method Methods 0.000 claims description 2
- 238000000635 electron micrograph Methods 0.000 claims description 2
- 238000001125 extrusion Methods 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- 239000006187 pill Substances 0.000 claims 1
- 239000000463 material Substances 0.000 description 12
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 9
- 238000007792 addition Methods 0.000 description 5
- 229910009043 WC-Co Inorganic materials 0.000 description 3
- 239000012300 argon atmosphere Substances 0.000 description 3
- 238000005056 compaction Methods 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000007373 indentation Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical group [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 101001034843 Mus musculus Interferon-induced transmembrane protein 1 Proteins 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical group [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910052804 chromium Chemical group 0.000 description 1
- 239000011651 chromium Chemical group 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000011156 metal matrix composite Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000007514 turning Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical group [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 1
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
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/02—Compacting only
-
- 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
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
- B22F3/15—Hot isostatic pressing
-
- 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
-
- 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
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
- C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
-
- 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
- C22C1/1084—Alloys containing non-metals by mechanical alloying (blending, milling)
-
- 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
- C22C29/067—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 comprising a particular metallic binder
-
- 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
-
- 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
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
Abstract
The invention relates to a nanoscale or ultrafine hard metal, comprising tungsten carbide, an additional metal carbide phase that has a cubic crystal structure, and a binder metal phase. The invention further relates to a method for producing said hard metal and to the use of said hard metal to produce tools and wearing parts. The invention further relates to a component that has been produced from the described hard metal.
Description
HARD METAL HAVING TOUGHNESS-INCREASING MICROSTRUCTURE
The present invention relates to a nanoscale or ultrafine cemented carbide including tungsten carbide, an additional metal carbide phase that is in a cubic crystal structure, and a binder metal phase, to a process for the preparation thereof, and to the use thereof for preparing tools and wear parts. Further, the present invention relates to a component prepared from the cemented carbide described.
Cemented carbides are metal matrix composite materials in which hard materials in the form of small particles are cemented together by a matrix of metal.
Cemented .. carbides are employed predominantly in applications in which materials having a high wear resistance and hardness while showing a high strength are required. Thus, cemented carbides are used, for example, as a cutting material for tools (such as turning tools, drills, and milling tools) and as wear-resistant matrices, e.g., in reforming or punching tools. However, conventional cemented carbides have the .. drawback of having a very low fracture toughness, which significantly limits their applicability. Conventionally, increasing the fracture toughness is possible by increasing the content of binder metal, which results in a decrease of hardness, however. Ideally, a tool made of a cemented carbide should have a high hardness while also having a high fracture toughness.
US 5,593,474 describes a sintered body of a composite material comprising a plurality of regions of a first metal carbide; and a plurality of regions of a second metal carbide, the first metal carbide having a larger particle size than the second metal carbide.
DE 10 2004 051 288 addressed the object or providing a polycrystalline powder of hard material with improved hardness while the toughness is maintained. This object is achieved by a polycrystalline powder of hard material consisting of polycrystalline grains of hard material, which are made of crystals of carbides, nitrides and/or carbonitrides of the transition metals of groups 4, 5 and 6 (titanium, vanadium and chromium groups) of the Periodic Table.
WO 2017/186468 relates to a cemented carbide comprising a phase of hard material grains and a phase of a heterogeneously distributed binder metal, wherein Date Recue/Date Received 2021-03-31
The present invention relates to a nanoscale or ultrafine cemented carbide including tungsten carbide, an additional metal carbide phase that is in a cubic crystal structure, and a binder metal phase, to a process for the preparation thereof, and to the use thereof for preparing tools and wear parts. Further, the present invention relates to a component prepared from the cemented carbide described.
Cemented carbides are metal matrix composite materials in which hard materials in the form of small particles are cemented together by a matrix of metal.
Cemented .. carbides are employed predominantly in applications in which materials having a high wear resistance and hardness while showing a high strength are required. Thus, cemented carbides are used, for example, as a cutting material for tools (such as turning tools, drills, and milling tools) and as wear-resistant matrices, e.g., in reforming or punching tools. However, conventional cemented carbides have the .. drawback of having a very low fracture toughness, which significantly limits their applicability. Conventionally, increasing the fracture toughness is possible by increasing the content of binder metal, which results in a decrease of hardness, however. Ideally, a tool made of a cemented carbide should have a high hardness while also having a high fracture toughness.
US 5,593,474 describes a sintered body of a composite material comprising a plurality of regions of a first metal carbide; and a plurality of regions of a second metal carbide, the first metal carbide having a larger particle size than the second metal carbide.
DE 10 2004 051 288 addressed the object or providing a polycrystalline powder of hard material with improved hardness while the toughness is maintained. This object is achieved by a polycrystalline powder of hard material consisting of polycrystalline grains of hard material, which are made of crystals of carbides, nitrides and/or carbonitrides of the transition metals of groups 4, 5 and 6 (titanium, vanadium and chromium groups) of the Periodic Table.
WO 2017/186468 relates to a cemented carbide comprising a phase of hard material grains and a phase of a heterogeneously distributed binder metal, wherein Date Recue/Date Received 2021-03-31
- 2 -said hard material grains have an average grain size within a range of from 1 nm to 1000 rim, and said heterogeneously distributed binder metal is present in the form of binder islands within the cemented carbide that have an average size 0.1 pm to 10 pm, and an average distance between neighboring binder islands of .5 from 1 pm to 7 pm.
EP 1 526 189 describes a cemented carbide comprising WC, a binder phase based on Co, Ni or Fe, and a gamma phase in which said gamma phase has an average particle size of less than 1 pm. Said gamma phase is prepared from presynthesized mixed carbides in the form (Me,W)C.
CN 103540823 describes a cemented carbide composition comprising from 40 to 50% by weight of WC, from 5 to 10% by weight of vanadium carbide, from 3 to 8% by weight of chromium carbide, from 5 to 9% by weight of titanium carbide, from 6 to 11% by weight of tantalum carbide, from 2 to 5% by weight of niobium carbide, and from 12 to 18% by weight of cobalt. The particle size of said WC
is within a range of from 0.1 to 0.8 pm.
EP 1 557 230 relates to a cemented carbide body comprising from 10 to 12% by weight of cobalt, less than 3% by weight of tantalum carbide, from 1 to 5.5%
by weight of niobium carbide, and from 3 to 5% by weight of titanium carbide, the balance being WC. Said WC has a particle size of from 0.4 to 1.5 pm, especially from 0.8 to 1.5 pm.
US 4,698,266 discloses a cutting tool comprising a maximum of 70% by weight of WC, and from 5 to 10% by weight of a cobalt binder phase, the rest of the composition being formed by metal carbides selected from the group consisting of TiC, TaC, NbC, HfC, and mixtures thereof. The average grain size of said WC is 2.5 from 0.9 to 1.3 pm.
Even if some solution approaches are already offered in the prior art, there is still no commercial solution for cemented carbides that have both a high hardness and wear resistance, and a high fracture toughness.
Date Recue/Date Received 2021-03-31
EP 1 526 189 describes a cemented carbide comprising WC, a binder phase based on Co, Ni or Fe, and a gamma phase in which said gamma phase has an average particle size of less than 1 pm. Said gamma phase is prepared from presynthesized mixed carbides in the form (Me,W)C.
CN 103540823 describes a cemented carbide composition comprising from 40 to 50% by weight of WC, from 5 to 10% by weight of vanadium carbide, from 3 to 8% by weight of chromium carbide, from 5 to 9% by weight of titanium carbide, from 6 to 11% by weight of tantalum carbide, from 2 to 5% by weight of niobium carbide, and from 12 to 18% by weight of cobalt. The particle size of said WC
is within a range of from 0.1 to 0.8 pm.
EP 1 557 230 relates to a cemented carbide body comprising from 10 to 12% by weight of cobalt, less than 3% by weight of tantalum carbide, from 1 to 5.5%
by weight of niobium carbide, and from 3 to 5% by weight of titanium carbide, the balance being WC. Said WC has a particle size of from 0.4 to 1.5 pm, especially from 0.8 to 1.5 pm.
US 4,698,266 discloses a cutting tool comprising a maximum of 70% by weight of WC, and from 5 to 10% by weight of a cobalt binder phase, the rest of the composition being formed by metal carbides selected from the group consisting of TiC, TaC, NbC, HfC, and mixtures thereof. The average grain size of said WC is 2.5 from 0.9 to 1.3 pm.
Even if some solution approaches are already offered in the prior art, there is still no commercial solution for cemented carbides that have both a high hardness and wear resistance, and a high fracture toughness.
Date Recue/Date Received 2021-03-31
- 3 -Therefore, it is the object of the present invention to provide a cemented carbide that pas an improved combination of hardness and fracture toughness, and preferably is accessible in a simple way.
Surprisingly, it has been found that this object is achieved by providing a nanoscale or ultrafine cemented carbide based on tungsten carbide, which further includes a metal carbide phase that is in a cubic crystal structure at room temperature.
Therefore, the present invention first relates to a cemented carbide, comprising a) a tungsten carbide phase having an average grain size of from 0.05 to 0.5 pm;
b) an additional metal carbide phase; and c) a binder metal phase, wherein said additional metal carbide phase is in a cubic crystal structure at room temperature, and wherein the proportion of said additional metal carbide phase in said cemented carbide is at least 4% by volume, based on the total volume of the cemented carbide, and wherein the average grain size was determined by the linear-intercept technique according to ISO 4499-2.
The conversion from percent by volume to percent by weight, or the conversion from percent by weight to percent by volume, is effected according to the following formulas:
m=vpi = ________ .avi = Pi) m, 1 ¨ \
E _____________________________________________ k-Pi) wherein m represents the mass proportion, vi represents the volume proportion, and pi represents the density of the respective component.
The cemented carbide according to the invention is a nanoscale or ultrafine cemented carbide, whose classification is effected in accordance with ISO 4499-2.
Date Recue/Date Received 2021-03-31
Surprisingly, it has been found that this object is achieved by providing a nanoscale or ultrafine cemented carbide based on tungsten carbide, which further includes a metal carbide phase that is in a cubic crystal structure at room temperature.
Therefore, the present invention first relates to a cemented carbide, comprising a) a tungsten carbide phase having an average grain size of from 0.05 to 0.5 pm;
b) an additional metal carbide phase; and c) a binder metal phase, wherein said additional metal carbide phase is in a cubic crystal structure at room temperature, and wherein the proportion of said additional metal carbide phase in said cemented carbide is at least 4% by volume, based on the total volume of the cemented carbide, and wherein the average grain size was determined by the linear-intercept technique according to ISO 4499-2.
The conversion from percent by volume to percent by weight, or the conversion from percent by weight to percent by volume, is effected according to the following formulas:
m=vpi = ________ .avi = Pi) m, 1 ¨ \
E _____________________________________________ k-Pi) wherein m represents the mass proportion, vi represents the volume proportion, and pi represents the density of the respective component.
The cemented carbide according to the invention is a nanoscale or ultrafine cemented carbide, whose classification is effected in accordance with ISO 4499-2.
Date Recue/Date Received 2021-03-31
- 4 -Within the scope of the present invention, "cemented carbide" describes a sintered composite material. Said additional metal carbide phase, which is in a cubic crystal structure at room temperature, i.e., at 25 C within the scope of the present invention, is hereinafter referred to interchangeably as a "cubic metal carbide".
The cemented carbide according to the invention has a high hardness and a high fracture toughness. The problem that the fracture toughness decreases as the hardness of the cemented carbide increases, i.e., that the material becomes brittle and friable, which occurs in conventional cemented carbides, was not observed in the case of the cemented carbide according to the invention. Without being bound by theory, it is considered that the positive properties of the cemented carbide according to the invention can be attributed, in particular, to the combination of the small grain size of the tungsten carbide and the presence of the cubic metal carbide phase. Therefore, the tungsten carbide used in the cemented carbide according to the invention has an average grain size of from 0.05 to 0.5 pm, preferably from 0.05 to 0.23 pm, more preferably from 0.05 to 0.09 pm, as determined by the linear-intercept technique according to ISO 4499-2 In a further preferred embodiment, the metal carbide phase that is in a cubic crystal structure at room temperature is selected from the group consisting of titanium carbide, tantalum carbide, niobium carbide, hafnium carbide, zirconium carbide, mixtures thereof, and mixed carbides of these compounds.
Preferably, the metal carbide phase used in the cemented carbide according to the invention has an average grain size of from 0.3 to 4.0 pm, preferably from 0.5 to 1.5 pm, as determined by the linear-intercept technique according to ISO 4499-2.
Surprisingly, it has been found that a particularly advantageous relationship of hardness and fracture toughness could be achieved if the metal carbide phases present in the cemented carbide according to the invention are homogeneously distributed. Therefore, an embodiment is preferred in which the metal carbide phase contained in the cemented carbide is in a periodically repeated distribution with an average distance of from 0.5 to 10 pm, preferably from 1 to 3 pm. Said average distance can be determined by linear analysis (linear-intercept technique) on electron micrographs of sections, and relates to the distance from grain center to grain center.
Without being bound by theory, the particularly homogeneous distribution of the Date Recue/Date Received 2021-03-31
The cemented carbide according to the invention has a high hardness and a high fracture toughness. The problem that the fracture toughness decreases as the hardness of the cemented carbide increases, i.e., that the material becomes brittle and friable, which occurs in conventional cemented carbides, was not observed in the case of the cemented carbide according to the invention. Without being bound by theory, it is considered that the positive properties of the cemented carbide according to the invention can be attributed, in particular, to the combination of the small grain size of the tungsten carbide and the presence of the cubic metal carbide phase. Therefore, the tungsten carbide used in the cemented carbide according to the invention has an average grain size of from 0.05 to 0.5 pm, preferably from 0.05 to 0.23 pm, more preferably from 0.05 to 0.09 pm, as determined by the linear-intercept technique according to ISO 4499-2 In a further preferred embodiment, the metal carbide phase that is in a cubic crystal structure at room temperature is selected from the group consisting of titanium carbide, tantalum carbide, niobium carbide, hafnium carbide, zirconium carbide, mixtures thereof, and mixed carbides of these compounds.
Preferably, the metal carbide phase used in the cemented carbide according to the invention has an average grain size of from 0.3 to 4.0 pm, preferably from 0.5 to 1.5 pm, as determined by the linear-intercept technique according to ISO 4499-2.
Surprisingly, it has been found that a particularly advantageous relationship of hardness and fracture toughness could be achieved if the metal carbide phases present in the cemented carbide according to the invention are homogeneously distributed. Therefore, an embodiment is preferred in which the metal carbide phase contained in the cemented carbide is in a periodically repeated distribution with an average distance of from 0.5 to 10 pm, preferably from 1 to 3 pm. Said average distance can be determined by linear analysis (linear-intercept technique) on electron micrographs of sections, and relates to the distance from grain center to grain center.
Without being bound by theory, the particularly homogeneous distribution of the Date Recue/Date Received 2021-03-31
- 5 -metal carbide phase in the cemented carbide according to the invention is attributed, inter alia, to the use of a tungsten carbide powder having the above mentioned grain sizes.
It has been found advantageous if powders having a particular particle size are used as starting materials for the tungsten carbide and the cubic metal carbide, wherein a "starting material" within the scope of the present invention means an unsintered powder. Therefore, in a preferred embodiment, a tungsten carbide powder having an average particle size dgET of from 0.05 to 0.30 pm, preferably from 0.05 to 0.25 pm, more preferably from 0.05 to 0.2 pm, is used as a starting material. The average particle size d1 is calculated from the specific surface area of the starting material as determined according to BET (BET surface area) by converting it according to the formula dBET = 6/(BET surface area * density). The specific surface area can be determined by the BET method according to DIN ISO 9277. The density corresponds to the physical density of the pure solid and can be extracted from the literature, the density of tungsten carbide usually being stated as 15.7 g/cm3.
As the starting material for the cubic metal carbide, there is preferably employed a cubic metal carbide powder having an average particle size dB ET of from 0.3 to 5 pm, more preferably from 0.4 to 1 pm, as determined according to the BET surface area of the starting material, and by conversion according to the formula dBET =
It has been found advantageous if powders having a particular particle size are used as starting materials for the tungsten carbide and the cubic metal carbide, wherein a "starting material" within the scope of the present invention means an unsintered powder. Therefore, in a preferred embodiment, a tungsten carbide powder having an average particle size dgET of from 0.05 to 0.30 pm, preferably from 0.05 to 0.25 pm, more preferably from 0.05 to 0.2 pm, is used as a starting material. The average particle size d1 is calculated from the specific surface area of the starting material as determined according to BET (BET surface area) by converting it according to the formula dBET = 6/(BET surface area * density). The specific surface area can be determined by the BET method according to DIN ISO 9277. The density corresponds to the physical density of the pure solid and can be extracted from the literature, the density of tungsten carbide usually being stated as 15.7 g/cm3.
As the starting material for the cubic metal carbide, there is preferably employed a cubic metal carbide powder having an average particle size dB ET of from 0.3 to 5 pm, more preferably from 0.4 to 1 pm, as determined according to the BET surface area of the starting material, and by conversion according to the formula dBET =
6/(BET
surface area * density). The physical density of the respective cubic carbide is to be used as said density. The values can be extracted from the literature.
In a preferred embodiment, the binder metal is a compound selected from the group consisting of cobalt, iron, nickel, and mixtures thereof. More preferably, the binder metal is cobalt. In a further preferred embodiment, the binder metal is a mixture consisting of iron, cobalt, and nickel, in which the proportion of the respective metals in the mixture is more than 1% by mass.
Surprisingly, it has been found that the sole addition of the cubic metal carbides as described above has no influence on grain growth during the production process, so that grain growth inhibitors may be optionally added to the cemented carbide according to the invention for reducing grain growth during the production process thereof. Therefore, an embodiment is preferred in which the cemented carbide further includes grain growth inhibitors, preferably those selected from the group Date Recue/Date Received 2021-03-31 consisting of vanadium carbide, chromium carbide, mixtures thereof, and mixed carbides of such compounds. The proportion of grain growth inhibitor in the cemented carbide is preferably from 0.05 to 6% by volume, based on the total volume of the cemented carbide.
Within the scope of the present invention, it has been found advantageous if the proportion of tungsten carbide in the cemented carbide according to the invention does not exceed a proportion of 950/0 by volume. Therefore, an embodiment is preferred in which the proportion of tungsten carbide in the cemented carbide according to the invention is from 40 to 80% by volume, based on the total volume of the cemented carbide. In this way, a sufficient hardness and fracture toughness of the cemented carbide can be ensured.
Further, it has been found advantageous to limit the proportion of binder metal in the cemented carbide. Therefore, an embodiment is preferred in which the proportion of binder metal in the cemented carbide according to the invention is not more than 40% by volume, preferably from 10 to 32% by volume, respectively based on the total volume of the cemented carbide.
Surprisingly, it has been found that the hardness of the cemented carbide can be increased while the fracture toughness is maintained, if the volume proportion of the additional metal carbide phase in the cemented carbide according to the invention comprises at least 4% by weight. Therefore, an embodiment is preferred in which the proportion of the additional metal carbide phase is from 4 to 30% by volume, preferably from 10 to 20% by volume, alternatively from 25 to 37% by volume, respectively based on the total volume of the cemented carbide.
In a particularly preferred embodiment, the cemented carbide according to the invention has the following composition:
i) from 40 to 90% by volume of tungsten carbide phase; and ii) from 10 to 32% by volume of binder metal phase; and balance: additional metal carbide phase;
Date Recue/Date Received 2021-03-31
surface area * density). The physical density of the respective cubic carbide is to be used as said density. The values can be extracted from the literature.
In a preferred embodiment, the binder metal is a compound selected from the group consisting of cobalt, iron, nickel, and mixtures thereof. More preferably, the binder metal is cobalt. In a further preferred embodiment, the binder metal is a mixture consisting of iron, cobalt, and nickel, in which the proportion of the respective metals in the mixture is more than 1% by mass.
Surprisingly, it has been found that the sole addition of the cubic metal carbides as described above has no influence on grain growth during the production process, so that grain growth inhibitors may be optionally added to the cemented carbide according to the invention for reducing grain growth during the production process thereof. Therefore, an embodiment is preferred in which the cemented carbide further includes grain growth inhibitors, preferably those selected from the group Date Recue/Date Received 2021-03-31 consisting of vanadium carbide, chromium carbide, mixtures thereof, and mixed carbides of such compounds. The proportion of grain growth inhibitor in the cemented carbide is preferably from 0.05 to 6% by volume, based on the total volume of the cemented carbide.
Within the scope of the present invention, it has been found advantageous if the proportion of tungsten carbide in the cemented carbide according to the invention does not exceed a proportion of 950/0 by volume. Therefore, an embodiment is preferred in which the proportion of tungsten carbide in the cemented carbide according to the invention is from 40 to 80% by volume, based on the total volume of the cemented carbide. In this way, a sufficient hardness and fracture toughness of the cemented carbide can be ensured.
Further, it has been found advantageous to limit the proportion of binder metal in the cemented carbide. Therefore, an embodiment is preferred in which the proportion of binder metal in the cemented carbide according to the invention is not more than 40% by volume, preferably from 10 to 32% by volume, respectively based on the total volume of the cemented carbide.
Surprisingly, it has been found that the hardness of the cemented carbide can be increased while the fracture toughness is maintained, if the volume proportion of the additional metal carbide phase in the cemented carbide according to the invention comprises at least 4% by weight. Therefore, an embodiment is preferred in which the proportion of the additional metal carbide phase is from 4 to 30% by volume, preferably from 10 to 20% by volume, alternatively from 25 to 37% by volume, respectively based on the total volume of the cemented carbide.
In a particularly preferred embodiment, the cemented carbide according to the invention has the following composition:
i) from 40 to 90% by volume of tungsten carbide phase; and ii) from 10 to 32% by volume of binder metal phase; and balance: additional metal carbide phase;
Date Recue/Date Received 2021-03-31
- 7 -wherein the proportion of the additional metal carbide phase is at least 4% by volume, based on the total volume of the cemented carbide, and wherein said percent by volume are respectively based on the total volume of the cemented carbide and sum up to 1000/0 by volume, optionally considering further components, .5 such as grain growth inhibitors.
Conventional cemented carbides have the disadvantage that although the hardness is increased by reducing the content of binder metal, the fracture toughness decreases. At the same time, an undesirable increase of thermal conductivity may occur. Surprisingly, it has been found that the cemented carbide according to the invention has an advantageous thermal conductivity. In a preferred embodiment, the cemented carbide according to the invention has a thermal conductivity of less than 50 W/m*K, preferably less than 40 W/m*K, as determined by the laser flash technique at 40 C.
In addition to an advantageous thermal conductivity, the cemented carbide according to the invention is further characterized by an improved fracture toughness.
Therefore, an embodiment is preferred in which the cemented carbide according to the invention has a fracture toughness of more than 8.0 MPa*rn1/2, as determined from Vickers hardness impressions according to the Pairnquist method as described in Shetty et al., Journal of Materials Science 20 (1985), pp. 1873 to 1882.
.. The present invention further relates to a process for the preparation of a cemented carbide according to the invention, comprising:
i) providing a powder mixture, including a) a tungsten carbide powder having an average particle size dBET of from 0.05 to 0.3 pm, preferably from 0.05 to 0.25 pm, more preferably from 0.05 to 0.2 pm;
b) an additional metal carbide powder that is in a cubic crystal structure at room temperature (25 C) and has an average particle size dBET of from 0.3 to 5 pm; and c) a binder metal powder; and Date Recue/Date Received 2021-03-31
Conventional cemented carbides have the disadvantage that although the hardness is increased by reducing the content of binder metal, the fracture toughness decreases. At the same time, an undesirable increase of thermal conductivity may occur. Surprisingly, it has been found that the cemented carbide according to the invention has an advantageous thermal conductivity. In a preferred embodiment, the cemented carbide according to the invention has a thermal conductivity of less than 50 W/m*K, preferably less than 40 W/m*K, as determined by the laser flash technique at 40 C.
In addition to an advantageous thermal conductivity, the cemented carbide according to the invention is further characterized by an improved fracture toughness.
Therefore, an embodiment is preferred in which the cemented carbide according to the invention has a fracture toughness of more than 8.0 MPa*rn1/2, as determined from Vickers hardness impressions according to the Pairnquist method as described in Shetty et al., Journal of Materials Science 20 (1985), pp. 1873 to 1882.
.. The present invention further relates to a process for the preparation of a cemented carbide according to the invention, comprising:
i) providing a powder mixture, including a) a tungsten carbide powder having an average particle size dBET of from 0.05 to 0.3 pm, preferably from 0.05 to 0.25 pm, more preferably from 0.05 to 0.2 pm;
b) an additional metal carbide powder that is in a cubic crystal structure at room temperature (25 C) and has an average particle size dBET of from 0.3 to 5 pm; and c) a binder metal powder; and Date Recue/Date Received 2021-03-31
- 8 -ii) forming and sintering the mixture.
The average particle size d BET is determined as described above from the BET
surface area and conversion according to the formula clBET 6/(BET surface area *
density).
The proportion of said additional cubic metal carbide powder in the powder mixture is selected for the cemented carbide obtained to have a proportion of at least 4% by volume of the cubic metal carbide phase, based on the total volume of the cemented carbide.
The binder metal powders as stated above are preferably used.
1 0 In a preferred embodiment, said forming and sintering of the mixture is performed to obtain a cemented carbide body. Said cemented carbide body may be, for example, a component.
In a preferred embodiment, the sintering within the scope of the process according to the invention is effected at a temperature of from 1150 to 1550 C. In this way, the cemented carbide according to the invention is accessible by a process that can be realized simply in industry.
Within the scope of the present invention, it has been surprisingly found that, for preparing the cemented carbide according to the invention, it is not necessary to use presynthesized mixed carbides of the form (Me,W)C, as described in the prior art.
Rather, the cemented carbide according to the invention can be prepared from the pure metal carbides or mixtures thereof.
The cemented carbide according to the invention is suitable, in particular, for use in fields of application in which a high hardness and at the same time a good fracture toughness are required. Therefore, the present invention further relates to the use of the cemented carbide according to the invention for the production of tools.
Preferably, the tools are tools with defined and undefined cutting edges, and tools for the machining of all kinds of materials.
Date Recue/Date Received 2021-03-31 -g -The present invention further relates to a component obtained by forming the cemented carbide according to the invention. Preferably, the component is selected from the group consisting of drills, solid carbide cutters, indexable inserts, saw teeth, forming dies, sealing rings, extrusion punches, press dies, and wear parts.
The present invention is further explained by means of the following Examples, which are by no means to be understood as limiting the idea of the invention.
Examples Example 1:
As the starting powder, a WC powder having a dBFT value of 90 nm, a cobalt metal powder having a d BET value of 205 nm, a TiC powder having a d BET value of 610 nm, a TaC powder having a dBET value of 370 nm, a Cr3C2 powder having a dBET value of 430 nm, and a VC powder having a nuil -BET value of 350 nm were used. A 200 g mixture of 62.7% by volume (77% by weight) WC, 15.9% by volume (11% by weight) Co, 12.9% by volume (5% by weight) TiC, 4.4% by volume (5% by weight) TaC, 1.9%
by volume (1% by weight) Cr3C2, and 2.2% by volume (1% by weight) VC was ground in n-heptane in a ball mill for 48 hours. The dispersion of cemented carbide obtained was dried and pressed uniaxially with a pressing power of 300 MPa into rectangular test specimens with a green density of > 50% of the density to be expected for a solid body (theoretical density). The test specimens were compacted under vacuum at a temperature of 1450 C and with a holding time of 30 min to above 95% of the theoretical density, followed by a final compaction under an argon atmosphere at the same temperature (Sinter-HIP technology). The test specimens proved to be completely dense under an optical microscope. The porosity according to ISO 4505 corresponded to > A02, BOO, COO. The Vickers hardness was determined to be 1770 1-11/10, and the fracture toughness (Kic) was calculated by measuring the crack lengths and using the formula of Shetty (Shetty 1985 -Indentation fracture of WC-Co cermets, see reference above) to be 9.5 MPa*m1/2.
The thermal conductivity (TC) was determined to be 29 W/m*K (measurement at 40 C by the laser flash technique).
Date Recue/Date Received 2021-03-31 -Table 1 shows the characteristics determined as compared to a cemented carbide having a composition without additions of cubic metal carbide, but with an otherwise comparable content of binder metal.
Example 2:
5 As the starting powder, a WC powder having a dBET value of 90 nm, a cobalt metal powder having a dBET value of 205 nm, a TiC powder having a dBET value of 610 nm, a TaC powder having a dBET value of 370 nm, a Cr3C2 powder having a dBET value of 430 nm, and a VC powder having a dBET value of 350 nm were used. A 200 g mixture of 68.9% by volume (80.6% by weight) WC, 16% by volume (10.6% by weight) 10 Co, 4% by volume (2.6% by weight) TiC, 7% by volume (4.3% by weight) TaC, 1.9% by volume (0.9% by weight) Cr3C2, and 2.2% by volume (1% by weight) VC
was ground in n-heptane in a ball mill for 48 hours. The dispersion of cemented carbide obtained was dried and pressed uniaxially with a pressing power of 300 MPa into rectangular test specimens with a green density of > 50% of the density to be expected for a solid body (theoretical density). The test specimens were compacted under vacuum at a temperature of 1450 C and with a holding time of 30 min to above 95% of the theoretical density, followed by a final compaction under an argon atmosphere at the same temperature (Sinter-HIP technology). The test specimens proved to be completely dense under an optical microscope. The porosity according to ISO 4505 corresponded to > A02, BOO, COO. The Vickers hardness was determined to be 1690 HV10, and the fracture toughness (Kic) was calculated by measuring the crack lengths and using the formula of Shetty (Shetty 1985 -Indentation fracture of WC-Co cermets, see reference above) to be 9.7 MPa*mil2.
The thermal conductivity (TC) was determined to be 39 W/m*K (measurement at 40 C by the laser flash technique).
Table 1 shows the characteristics determined as compared to the characteristics from Example 1.
Table 1: Composition and achieved hardness, fracture toughness, and thermal conductivity of nanoscale or ultrafine cemented carbides having a content of binder metal of 16 0.2% by volume with and without additions of cubic metal carbide (MeC) of 17 and 11% by volume, respectively.
Date Recue/Date Received 2021-03-31 Camp.
Ex. without MeC WC Co TIC TaC Cr3C2 VC
hardness 1783 + 20 HV10 % by weight J89 1 10::: :9 8.9 mpern1./2 : %byvolume 147:: :16,2 0 õ013H 0:4 TC
50 W/m*K
hardness 1770 20 HVIO
Ex. 1 17% by volume Kic 9.5 MPa*
MeC WC Co TIC TaC Cr3C2 j_ VC IC 29 W/m*K
:%byvolurne 627 '159 12:.9 : :4.4 1922 hardness 1690 20 liV10 Ex. 2 11% by yolurnP. K1c 9_7 NAPA*
MeC WC Co TIC TaC Cr3C2 VC TC 39 W/m*K
% by weight 806H.:19;k, E% by volume:, ,68.9 :16E" , 4:, :19 22 Example 3:
As the starting powder, a WC powder having a dBET value of 90 nm, a cobalt metal powder having a d BET value of 205 nm, a TiC powder having a d BET value of 610 nm, a TaC powder having a dDET value of 370 nm, a Cr3C2 powder having a dBET value of 430 nm, and a VC powder having a clBET value of 350 nm were used. A 200 g mixture of 68.5% by volume (79.1% by weight) WC, 10% by volume (6.5% by weight) Co, 10.1% by volume (3.7% by weight) TiC, 9% by volume (9.6% by weight) TaC, 1.2% by volume (0.6% by weight) Cr3C2 and 1.2% by volume (0.5% by weight) VC was ground in n-heptane in a ball mill for 44 hours. The dispersion of cemented carbide obtained was dried and pressed uniaxially with a pressing power of 300 MPa into rectangular test specimens with a green density of > 50% of the density to be expected for a solid body (theoretical density). The test specimens were compacted under vacuum at a temperature of 1460 C and with a holding time of 30 min to above 95% of the theoretical density, followed by a final compaction under an argon atmosphere at the same temperature (Sinter-HIP technology). The test specimens proved to be completely dense under an optical microscope. The porosity according to ISO 4505 corresponded to > A02, BOO, COO. The Vickers hardness was determined to be 2020 HV10, and the fracture toughness (Kic) was calculated by measuring the crack lengths and using the formula of Shetty (Shetty 1985 -Indentation fracture of WC-Co cermets, see reference above) to be 8.5 MPa* im /2.
Date Recue/Date Received 2021-03-31 The thermal conductivity was determined to be 35 W/m*K (measurement at 40 C
by the laser flash technique).
Table 2 shows the characteristics determined as compared to a cemented carbide having a composition without additions of cubic metal carbide, but with an otherwise comparable content of binder metal.
Table 2: Composition and achieved hardness, fracture toughness, and thermal conductivity of nanoscale or ultrafine cemented carbides having a content of binder metal of 10 0.2% by volume with and without additions of cubic metal carbide (MeC).
Comp. hardness 2010 without MeC WC Co TIC TaC Cr3C2 VC
Ex. HV10 % by weight 93.1 6 0, 0 0,6 0.3 Kw 8.0 MPa*mu2 % by volume 87.9 10 0 0 1.3 0.8 TC 61 W/m*K
Ex. 3 19 % by volume WC Co TIC TaC Cr3C2 VC hardness 2020 MeC HV10 % by weight 79.1 6.5 3.7 9.6 0.6 0.5 Kw 8.5 MPa*m1/2 % by volume 68.5 10.0 10.1 9.0 1.2 1.2 TC 35 W/m*K
F
As can be seen from Tables 1 and 2, the cemented carbides of the invention according to the Examples have a fracture toughness that is improved over that of conventional cemented carbides, and a lower thermal conductivity without adversely affecting the Vickers hardness of the cemented carbides according to the invention within the accepted tolerance of 20 HV10.
Figure 1 shows a scanning electron micrograph of a cemented carbide according to the invention, which shows the periodically repeated distribution of the additional metal carbide phase with an average distance of about 1 to 3 pm.
The picture was recorded on an electron microscope with an EsB detector having an acceleration voltage of 2 kV and a 10,000 x magnification. The numbers represent:
Date Recue/Date Received 2021-03-31 1 - tungsten carbide phase 2 - cubic metal carbide phase 3 - binder metal phase Date Recue/Date Received 2021-03-31
The average particle size d BET is determined as described above from the BET
surface area and conversion according to the formula clBET 6/(BET surface area *
density).
The proportion of said additional cubic metal carbide powder in the powder mixture is selected for the cemented carbide obtained to have a proportion of at least 4% by volume of the cubic metal carbide phase, based on the total volume of the cemented carbide.
The binder metal powders as stated above are preferably used.
1 0 In a preferred embodiment, said forming and sintering of the mixture is performed to obtain a cemented carbide body. Said cemented carbide body may be, for example, a component.
In a preferred embodiment, the sintering within the scope of the process according to the invention is effected at a temperature of from 1150 to 1550 C. In this way, the cemented carbide according to the invention is accessible by a process that can be realized simply in industry.
Within the scope of the present invention, it has been surprisingly found that, for preparing the cemented carbide according to the invention, it is not necessary to use presynthesized mixed carbides of the form (Me,W)C, as described in the prior art.
Rather, the cemented carbide according to the invention can be prepared from the pure metal carbides or mixtures thereof.
The cemented carbide according to the invention is suitable, in particular, for use in fields of application in which a high hardness and at the same time a good fracture toughness are required. Therefore, the present invention further relates to the use of the cemented carbide according to the invention for the production of tools.
Preferably, the tools are tools with defined and undefined cutting edges, and tools for the machining of all kinds of materials.
Date Recue/Date Received 2021-03-31 -g -The present invention further relates to a component obtained by forming the cemented carbide according to the invention. Preferably, the component is selected from the group consisting of drills, solid carbide cutters, indexable inserts, saw teeth, forming dies, sealing rings, extrusion punches, press dies, and wear parts.
The present invention is further explained by means of the following Examples, which are by no means to be understood as limiting the idea of the invention.
Examples Example 1:
As the starting powder, a WC powder having a dBFT value of 90 nm, a cobalt metal powder having a d BET value of 205 nm, a TiC powder having a d BET value of 610 nm, a TaC powder having a dBET value of 370 nm, a Cr3C2 powder having a dBET value of 430 nm, and a VC powder having a nuil -BET value of 350 nm were used. A 200 g mixture of 62.7% by volume (77% by weight) WC, 15.9% by volume (11% by weight) Co, 12.9% by volume (5% by weight) TiC, 4.4% by volume (5% by weight) TaC, 1.9%
by volume (1% by weight) Cr3C2, and 2.2% by volume (1% by weight) VC was ground in n-heptane in a ball mill for 48 hours. The dispersion of cemented carbide obtained was dried and pressed uniaxially with a pressing power of 300 MPa into rectangular test specimens with a green density of > 50% of the density to be expected for a solid body (theoretical density). The test specimens were compacted under vacuum at a temperature of 1450 C and with a holding time of 30 min to above 95% of the theoretical density, followed by a final compaction under an argon atmosphere at the same temperature (Sinter-HIP technology). The test specimens proved to be completely dense under an optical microscope. The porosity according to ISO 4505 corresponded to > A02, BOO, COO. The Vickers hardness was determined to be 1770 1-11/10, and the fracture toughness (Kic) was calculated by measuring the crack lengths and using the formula of Shetty (Shetty 1985 -Indentation fracture of WC-Co cermets, see reference above) to be 9.5 MPa*m1/2.
The thermal conductivity (TC) was determined to be 29 W/m*K (measurement at 40 C by the laser flash technique).
Date Recue/Date Received 2021-03-31 -Table 1 shows the characteristics determined as compared to a cemented carbide having a composition without additions of cubic metal carbide, but with an otherwise comparable content of binder metal.
Example 2:
5 As the starting powder, a WC powder having a dBET value of 90 nm, a cobalt metal powder having a dBET value of 205 nm, a TiC powder having a dBET value of 610 nm, a TaC powder having a dBET value of 370 nm, a Cr3C2 powder having a dBET value of 430 nm, and a VC powder having a dBET value of 350 nm were used. A 200 g mixture of 68.9% by volume (80.6% by weight) WC, 16% by volume (10.6% by weight) 10 Co, 4% by volume (2.6% by weight) TiC, 7% by volume (4.3% by weight) TaC, 1.9% by volume (0.9% by weight) Cr3C2, and 2.2% by volume (1% by weight) VC
was ground in n-heptane in a ball mill for 48 hours. The dispersion of cemented carbide obtained was dried and pressed uniaxially with a pressing power of 300 MPa into rectangular test specimens with a green density of > 50% of the density to be expected for a solid body (theoretical density). The test specimens were compacted under vacuum at a temperature of 1450 C and with a holding time of 30 min to above 95% of the theoretical density, followed by a final compaction under an argon atmosphere at the same temperature (Sinter-HIP technology). The test specimens proved to be completely dense under an optical microscope. The porosity according to ISO 4505 corresponded to > A02, BOO, COO. The Vickers hardness was determined to be 1690 HV10, and the fracture toughness (Kic) was calculated by measuring the crack lengths and using the formula of Shetty (Shetty 1985 -Indentation fracture of WC-Co cermets, see reference above) to be 9.7 MPa*mil2.
The thermal conductivity (TC) was determined to be 39 W/m*K (measurement at 40 C by the laser flash technique).
Table 1 shows the characteristics determined as compared to the characteristics from Example 1.
Table 1: Composition and achieved hardness, fracture toughness, and thermal conductivity of nanoscale or ultrafine cemented carbides having a content of binder metal of 16 0.2% by volume with and without additions of cubic metal carbide (MeC) of 17 and 11% by volume, respectively.
Date Recue/Date Received 2021-03-31 Camp.
Ex. without MeC WC Co TIC TaC Cr3C2 VC
hardness 1783 + 20 HV10 % by weight J89 1 10::: :9 8.9 mpern1./2 : %byvolume 147:: :16,2 0 õ013H 0:4 TC
50 W/m*K
hardness 1770 20 HVIO
Ex. 1 17% by volume Kic 9.5 MPa*
MeC WC Co TIC TaC Cr3C2 j_ VC IC 29 W/m*K
:%byvolurne 627 '159 12:.9 : :4.4 1922 hardness 1690 20 liV10 Ex. 2 11% by yolurnP. K1c 9_7 NAPA*
MeC WC Co TIC TaC Cr3C2 VC TC 39 W/m*K
% by weight 806H.:19;k, E% by volume:, ,68.9 :16E" , 4:, :19 22 Example 3:
As the starting powder, a WC powder having a dBET value of 90 nm, a cobalt metal powder having a d BET value of 205 nm, a TiC powder having a d BET value of 610 nm, a TaC powder having a dDET value of 370 nm, a Cr3C2 powder having a dBET value of 430 nm, and a VC powder having a clBET value of 350 nm were used. A 200 g mixture of 68.5% by volume (79.1% by weight) WC, 10% by volume (6.5% by weight) Co, 10.1% by volume (3.7% by weight) TiC, 9% by volume (9.6% by weight) TaC, 1.2% by volume (0.6% by weight) Cr3C2 and 1.2% by volume (0.5% by weight) VC was ground in n-heptane in a ball mill for 44 hours. The dispersion of cemented carbide obtained was dried and pressed uniaxially with a pressing power of 300 MPa into rectangular test specimens with a green density of > 50% of the density to be expected for a solid body (theoretical density). The test specimens were compacted under vacuum at a temperature of 1460 C and with a holding time of 30 min to above 95% of the theoretical density, followed by a final compaction under an argon atmosphere at the same temperature (Sinter-HIP technology). The test specimens proved to be completely dense under an optical microscope. The porosity according to ISO 4505 corresponded to > A02, BOO, COO. The Vickers hardness was determined to be 2020 HV10, and the fracture toughness (Kic) was calculated by measuring the crack lengths and using the formula of Shetty (Shetty 1985 -Indentation fracture of WC-Co cermets, see reference above) to be 8.5 MPa* im /2.
Date Recue/Date Received 2021-03-31 The thermal conductivity was determined to be 35 W/m*K (measurement at 40 C
by the laser flash technique).
Table 2 shows the characteristics determined as compared to a cemented carbide having a composition without additions of cubic metal carbide, but with an otherwise comparable content of binder metal.
Table 2: Composition and achieved hardness, fracture toughness, and thermal conductivity of nanoscale or ultrafine cemented carbides having a content of binder metal of 10 0.2% by volume with and without additions of cubic metal carbide (MeC).
Comp. hardness 2010 without MeC WC Co TIC TaC Cr3C2 VC
Ex. HV10 % by weight 93.1 6 0, 0 0,6 0.3 Kw 8.0 MPa*mu2 % by volume 87.9 10 0 0 1.3 0.8 TC 61 W/m*K
Ex. 3 19 % by volume WC Co TIC TaC Cr3C2 VC hardness 2020 MeC HV10 % by weight 79.1 6.5 3.7 9.6 0.6 0.5 Kw 8.5 MPa*m1/2 % by volume 68.5 10.0 10.1 9.0 1.2 1.2 TC 35 W/m*K
F
As can be seen from Tables 1 and 2, the cemented carbides of the invention according to the Examples have a fracture toughness that is improved over that of conventional cemented carbides, and a lower thermal conductivity without adversely affecting the Vickers hardness of the cemented carbides according to the invention within the accepted tolerance of 20 HV10.
Figure 1 shows a scanning electron micrograph of a cemented carbide according to the invention, which shows the periodically repeated distribution of the additional metal carbide phase with an average distance of about 1 to 3 pm.
The picture was recorded on an electron microscope with an EsB detector having an acceleration voltage of 2 kV and a 10,000 x magnification. The numbers represent:
Date Recue/Date Received 2021-03-31 1 - tungsten carbide phase 2 - cubic metal carbide phase 3 - binder metal phase Date Recue/Date Received 2021-03-31
Claims (16)
1. A cernented carbide, comprising a) a tungsten carbide phase having an average grain size of from 0.05 to 0.5 pm, preferably frorn 0.05 to 0.23 pm, more preferably from 0.05 to 0.09 pm;
b) an additional metal carbide phase; and c) a binder metal phase, wherein said additional metal carbide phase is in a cubic crystal structure at room temperature, and wherein the proportion of said additional metal carbide phase in said cemented carbide is at least 4% by volume, based on the total volume of the cemented carbide, and wherein the average grain size was determined by the linear-intercept technique according to ISO 4499-2.
b) an additional metal carbide phase; and c) a binder metal phase, wherein said additional metal carbide phase is in a cubic crystal structure at room temperature, and wherein the proportion of said additional metal carbide phase in said cemented carbide is at least 4% by volume, based on the total volume of the cemented carbide, and wherein the average grain size was determined by the linear-intercept technique according to ISO 4499-2.
2. The cemented carbide according to claim 1, characterized in that said additional metal carbide phase is selected frorn the group consisting of titaniurn carbide (TiC), tantalum carbide (TaC), niobium carbide (NbC), hafnium carbide (HfC), zirconium carbide, mixtures thereof, and mixed carbides of these compounds.
3. The cemented carbide according to clairn 1 or 2, characterized in that said additional metal carbide phase has an average grain size of from 0.3 to 4 pm, preferably from 0.5 to 1.5 pm, as determined by the linear-intercept technique according to ISO 4499-2.
4. The cernented carbide according to at least one of the preceding claims, characterized in that said additional metal carbide phase in the cemented carbide is in a periodically repeated distribution with an average distance of from 0.5 to 10 pm, preferably from 1 to 31_1111, as determined by linear analysis (linear-intercept technique) on electron micrographs of sections.
5. The cemented carbide according to at least one of the preceding claims, characterized in that a tungsten carbide powder having an average particle size d BET of from 0.05 to 0.3 pm, preferably from 0.05 to 0.25 pill, more preferably from 0.05 to 0.2 pm, is used as a starting material, as determined according to the BET surface area by converting it according to the formula d BET = 6/(BET surface area * density).
6. The cemented carbide according to at least one of the preceding claims, characterized in that a metal carbide powder having an average particle size d BET of from 0.3 to 5 pm, more preferably from 0.4 to 1 pm, is used as a starting material, as determined according to the BET surface area, and by conversion according to the formula dBET = 6/(BET surface area * density)õ
7. The cemented carbide according to at least one of the preceding claims, characterized in that said binder metal phase is selected from the group consisting of iron, cobalt, nickel, and mixtures thereof.
8. The cemented carbide according to claim 7, characterized in that said binder metal phase is a mixture consisting of iron, cobalt, and nickel, in which the respective contents of the components are more than 1% by mass.
9. The cemented carbide according to at least one of the preceding claims, characterized in that said cemented carbide further includes grain growth inhibitors, preferably those selected from the group consisting of vanadium carbide, chromium carbide, mixtures thereof, and mixed carbides of such compounds.
10. The cernented carbide according to at least one of the preceding claims, characterized in that said tungsten carbide phase in the cemented carbide comprises from 40 to 90% by volume, based on the total volume of the cemented carbide.
11. The cemented carbide according to at least one of the preceding claims, characterized in that said cemented carbide has a thermal conductivity of less than 50 W/m*K, as determined by the laser flash technique at 40 C.
12. A process for the preparation of a cemented carbide according to one or more of claims 1 to 11, comprising the steps of:
i) providing a powder mixture, including a) a tungsten carbide powder having an average particle size dBET of from 0.05 to 0.3 pm;
b) an additional metal carbide powder that is in a cubic crystal structure at room temperature (25 C) and has an average particle size dBET of from 0.3 to 5 pm; and c) a binder metal powder; and ii) forming and sintering the mixture.
i) providing a powder mixture, including a) a tungsten carbide powder having an average particle size dBET of from 0.05 to 0.3 pm;
b) an additional metal carbide powder that is in a cubic crystal structure at room temperature (25 C) and has an average particle size dBET of from 0.3 to 5 pm; and c) a binder metal powder; and ii) forming and sintering the mixture.
13. The process according to claim 12, characterized in that said sintering is effected at a temperature of from 1150 to 1550 C.
14. Use of a cemented carbide according to one or more of claims 1 to 11 for the production of tools.
15. A component, characterized by being obtained by forming the cemented carbide according to one or more of claims 1 to 11.
16. The component according to claim 15, characterized in that said component is drills, solid carbide cutters, indexable inserts, saw teeth, forming dies, sealing rings, extrusion punches, press dies, and wear parts.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP18200028 | 2018-10-12 | ||
| EP18200028.1 | 2018-10-12 | ||
| PCT/EP2019/075352 WO2020074241A1 (en) | 2018-10-12 | 2019-09-20 | Hard metal having toughness-increasing microstructure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA3114969A1 true CA3114969A1 (en) | 2020-04-16 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA3114969A Pending CA3114969A1 (en) | 2018-10-12 | 2019-09-20 | Hard metal having toughness-increasing microstructure |
Country Status (9)
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| US (1) | US20220267882A1 (en) |
| EP (1) | EP3864183A1 (en) |
| JP (1) | JP2022504253A (en) |
| KR (1) | KR20210075078A (en) |
| CN (2) | CN112840050B (en) |
| CA (1) | CA3114969A1 (en) |
| IL (1) | IL281952A (en) |
| MX (1) | MX2021003781A (en) |
| WO (1) | WO2020074241A1 (en) |
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|---|---|---|---|---|
| WO2020086971A1 (en) | 2018-10-26 | 2020-04-30 | Oerlikon Metco (Us) Inc. | Corrosion and wear resistant nickel based alloys |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4698266A (en) * | 1985-11-18 | 1987-10-06 | Gte Laboratories Incorporated | Coated cemented carbide tool for steel roughing applications and methods for machining |
| US5593474A (en) | 1988-08-04 | 1997-01-14 | Smith International, Inc. | Composite cemented carbide |
| SE527348C2 (en) * | 2003-10-23 | 2006-02-14 | Sandvik Intellectual Property | Ways to make a cemented carbide |
| SE527679C2 (en) * | 2004-01-26 | 2006-05-09 | Sandvik Intellectual Property | Carbide body, especially spiral drill, and its use for rotary metalworking tools |
| DE102004051288B4 (en) | 2004-10-15 | 2009-04-16 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Polycrystalline hard material powder, composite material with a polycrystalline hard material powder and method for producing a polycrystalline hard material powder |
| CN103540823A (en) * | 2013-10-17 | 2014-01-29 | 常熟市良益金属材料有限公司 | Hard alloy |
| DE102016207028A1 (en) | 2016-04-26 | 2017-10-26 | H.C. Starck Gmbh | Carbide with toughening structure |
| CN108570589B (en) * | 2018-04-09 | 2020-05-05 | 广东翔鹭钨业股份有限公司 | Hard alloy cutter material and preparation method thereof |
-
2019
- 2019-09-20 CA CA3114969A patent/CA3114969A1/en active Pending
- 2019-09-20 CN CN201980065576.7A patent/CN112840050B/en active Active
- 2019-09-20 CN CN202310280386.5A patent/CN116287927A/en active Pending
- 2019-09-20 EP EP19769529.9A patent/EP3864183A1/en active Pending
- 2019-09-20 WO PCT/EP2019/075352 patent/WO2020074241A1/en active Application Filing
- 2019-09-20 US US17/282,062 patent/US20220267882A1/en active Pending
- 2019-09-20 KR KR1020217009568A patent/KR20210075078A/en not_active Application Discontinuation
- 2019-09-20 MX MX2021003781A patent/MX2021003781A/en unknown
- 2019-09-20 JP JP2021518593A patent/JP2022504253A/en active Pending
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2021
- 2021-03-31 IL IL281952A patent/IL281952A/en unknown
Also Published As
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|---|---|
| CN112840050B (en) | 2023-06-09 |
| JP2022504253A (en) | 2022-01-13 |
| CN116287927A (en) | 2023-06-23 |
| KR20210075078A (en) | 2021-06-22 |
| CN112840050A (en) | 2021-05-25 |
| MX2021003781A (en) | 2021-05-27 |
| WO2020074241A1 (en) | 2020-04-16 |
| IL281952A (en) | 2021-05-31 |
| US20220267882A1 (en) | 2022-08-25 |
| EP3864183A1 (en) | 2021-08-18 |
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