Superhard composite member and method of manufacturing the same

• US 5,889,219 A
• Filed: 11/12/1996
• Issued: 03/30/1999
• Est. Priority Date: 11/15/1995
• Status: Expired due to Term

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Otsuka, Michio, Arisawa, Yoshifumi, Moriguchi, Hideki
• Primary Examiner(s): MAI, NGOCLAN THI
• Application Number:
  US08/745,422
• Time in Patent Office: 868 Days
• Field of Search: 75/236, 75/238, 75/242, 51/307, 428/552, 419/13, 419/14, 419/16, 419/18, 419/23, 419/35, 419/48
• US Class Current: 75/236
• CPC Class Codes: B22F 1/06 Metallic powder characterised by the shape of the particles nanosized particles B22F1/054
• CPC Class Codes: B22F 2005/001 Cutting tools, earth boring or grinding tool other than table ware
• CPC Class Codes: B22F 2009/041 by mechanical alloying, e.g. blending, milling
• CPC Class Codes: B22F 2207/03 of the metallic binder phase in cermets
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 3/1035 Liquid phase sintering
• CPC Class Codes: B22F 3/105 by using electric current other than for infrared radiant energy, laser radiation or plasma B22F3/11 takes precedence; by ultrasonic bonding B22F3/115 takes precedence
• CPC Class Codes: B22F 9/04 starting from solid material, e.g. by crushing, grinding or milling C22C1/1084 takes precedence; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C
• CPC Class Codes: B24B 41/00 Component parts such as frames, beds, carriages, headstocks
• CPC Class Codes: B24D 99/005 Segments of abrasive wheels
• CPC Class Codes: C22C 1/051 Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
• CPC Class Codes: C22C 26/00 Alloys containing diamond or cubic or wurtzitic boron nitride, fullerenes or carbon nanotubes
• CPC Class Codes: Y10T 428/12056 Entirely inorganic

Abstract

A sintered body having diamond grains dispersed and held in a matrix of cemented carbide or cermet is obtained by direct resistance heating and pressurized sintering. The sintering is performed at a liquid phase generating temperature in a short time, so that the diamond grains are not directly bonded to each other. Thus, a superhard composite member that has excellent hardness and wear resistance can be obtained without employing an ultra high-pressure vessel.

Claims

1. A superhard composite member comprising:

a hard phase consisting of a material containing at least one element selected from a group of WC, TiC, TiN and Ti(C,N);

a binder phase being mainly composed of an iron family metal; and

a plurality of diamond grains being dispersed in a structure including said hard phase and said binder phase;

wherein said hard phase, said binder phase and said diamond grains have been formed by direct resistance heating and pressurized sintering under such conditions that diamond is thermodynamically metastable and a liquid phase is present; and

wherein said composite member has apparent porosity satisfying the range of A00 to A08 and B00 to B08 according to ISO standards.

2. The superhard composite member in accordance with claim 1, wherein said hard phase is WC, and said binder phase is Co.

3. The superhard composite member in accordance with claim 1, wherein said binder phase contains Co having a main crystal system being f.c.c.

4. The superhard composite member in accordance with claim 1, wherein said conditions include a temperature allowing appearance of said liquid phase that is higher than 1300°

C.

5. The superhard composite member in accordance with claim 1, wherein each said diamond grain comprises a core and an outer coating on said core, wherein said outer coating consists of at least one metal selected from a group consisting of Ir, Os, Pt, Re, Rh, Cr, Mo and W.

6. The superhard composite member in accordance with claim 5, wherein each said diamond grain further comprises an inner coating consisting of at least one metal selected from Co and Ni that is provided between said outer coating and said core of each said diamond grain.

7. The superhard composite member in accordance with claim 5, comprising at least one element selected from a group consisting of W, Ti, Co and Ni diffused in said outer coating.

8. The superhard composite member in accordance with claim 2, containing crystals of said WC, wherein at least 50% of all of said crystals of WC have a grain size larger than 3 μ

m as determined in an area ratio on an arbitrary cross section through said composite member.

9. The superhard composite member in accordance with claim 2, containing crystals of said WC, wherein at least 10% to 35% of all of said crystals of WC have a grain size smaller than 1 μ

m as determined in an area ratio on an arbitrary cross section through said composite member.

10. The superhard composite member in accordance with claim 2, wherein said WC has a mean grain size smaller than 1 μ

m.

11. The superhard composite member in accordance with claim 2, wherein said WC has a mean grain size smaller than 3 μ

m, and said diamond grains have a mean grain size smaller than 10 μ

m.

12. The superhard composite member in accordance with claim 2, having a section plane on which (001) planes of crystals of said WC are particularly developed.

13. The superhard composite member in accordance with claim 12, wherein V(001)/V(101) is larger than 0.5 and H(001)/H(101) is smaller than 0.45, wherein V(001) and V(101) respectively represent peak strength values of (001) and (101) planes of said WC crystals by X-ray diffraction on a first section plane which is perpendicular with respect to a pressure axis for said direct resistance heating and pressurized sintering, and H(001) and H(101) respectively represent peak strength values of said (001) and (101) planes of said WC crystals by X-ray diffraction on a second section plane which is parallel with respect to said pressure axis.

14. The superhard composite member in accordance with claim 1, comprising free carbon present in an interior of said composite member.

15. The superhard composite member in accordance with claim 1, having an interface between said hard phase and said diamond grains, and comprising at least one component being selected from carbides of elements belonging to the groups IVa, Va and VIa of the periodic table and SiC deposited on at least a part of said interface between said hard phase and said diamond grains.

16. The superhard composite member in accordance with claim 1, wherein said diamond grains have a mean grain size in a range from 10 to 1000 μ

m.

17. The superhard composite member in accordance with claim 1, wherein a content of said diamond grains is 5 to 50 vol. % of said composite member.

18. The superhard composite member in accordance with claim 1, wherein a content of said binder phase is 10 to 50 vol. % of said composite member.

19. The superhard composite member in accordance with claim 1, wherein a content proportion of said diamond grains varies in a thickness direction so as to be greater toward a first surface of said superhard composite member and lesser toward a second surface of said superhard composite member opposite said first surface.

20. The superhard composite member in accordance with claim 1, further in combination with and connected onto a substrate containing at least any one of WC cemented carbide, TiC(N) cermet and a metal material.

21. The superhard composite member in accordance with claim 1, further comprising at least any one of cubic boron nitride and wurtzite boron nitride also dispersed in said structure including said hard phase and said binder phase.

22. The superhard composite member in accordance with claim 1, wherein said plurality of diamond grains have at least either a structure including no diamond skeletons or a structure including no parts where said diamond grains are directly bonded to each other.

23. The superhard composite member in accordance with claim 22, being configured and adapted as a cutter bit for a shield machine.

25. A method of manufacturing the superhard composite member of claim 1, said method comprising the steps of:

mixing raw powder materials including a diamond powder containing said diamond grains, a hard phase powder containing said material of said hard phase, and a binder phase powder containing said iron family metal, with each other for obtaining a mixed raw material; and

sintering said mixed raw material by directly resistance heating said mixed raw material to a prescribed temperature and applying a prescribed pressure to said mixed raw material.

26. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said prescribed temperature is at least 1100°

C. and not more than 1350°

C., and said prescribed pressure is at least 5 MPa and not more than 200 MPa.

27. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said step of obtaining said mixed raw material further includes a step of coating at least any one of said diamond powder and said hard phase powder with at least either Co or Ni.

28. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said step of obtaining said mixed raw material further includes a step of coating said diamond powder with at least one metal being selected from a group consisting of Ir, Os, Pt, Re, Rh, Cr, Mo and W.

29. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said raw powder materials further include at least one metal being selected from elements belonging to the groups IVa, Va and VIa of the periodic table and Si.

30. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said step of mixing said raw powder materials comprises using mechanical alloying.

31. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said sintering is carried out for a time not greater than 10 minutes.

32. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said sintering is performed while allowing appearance of a liquid phase.

33. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said step of obtaining said mixed raw material further includes a step of obtaining a plurality of types of mixed raw materials respectively having different mixing ratios of said diamond powder,

wherein said plurality of types of mixed raw materials are arranged in order of said mixing ratios of said diamond powder and sintered in said sintering step, thereby varying a proportional content of said diamond grains in a thickness direction of said composite member.

34. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said sintering step further includes a step of arranging said mixed raw material on a substrate to provide a composite body, heating said composite body of said mixed raw material and said substrate by resistance heating, and sintering said mixed raw material thereby obtaining a sintered body while sintering and bonding said sintered body onto said substrate.

35. The method of manufacturing a superhard composite member in accordance with claim 34, wherein said step of obtaining said mixed raw material further includes a step of obtaining a plurality of types of mixed raw materials respectively having different mixing ratios of said diamond powder,

wherein said plurality of types of mixed raw materials are arranged on said substrate in order of said mixing ratios of said diamond powder and sintered in said sintering step, thereby varying a proportional content of said diamond grains in a thickness direction of said composite member.

36. The method of manufacturing a superhard composite member in accordance with claim 25, wherein said raw powder materials further include at least any one of cubic boron nitride and wurtzite boron nitride that is mixed together with said diamond powder, said hard phase powder and said binder phase powder.

24. A superhard composite member comprising a hard phase being mainly composed of WC, a binder phase being mainly composed of Co, and a plurality of diamond grains being dispersed in a structure including said hard phase and said binder phase,

the main crystal system of said Co being f.c.c.,

superhard composite member containing at least 5 vol. % and not more than 50 vol. % of said diamond grains with no parts where said diamond grains are directly bonded to each other, and

said superhard composite member having apparent porosity satisfying the range of A00 to A08 and B00 to B08 according to ISO standards.