EP1715972A1 - Method of sintering body having high hardness - Google Patents

Method of sintering body having high hardness

Info

Publication number
EP1715972A1
EP1715972A1 EP05721763A EP05721763A EP1715972A1 EP 1715972 A1 EP1715972 A1 EP 1715972A1 EP 05721763 A EP05721763 A EP 05721763A EP 05721763 A EP05721763 A EP 05721763A EP 1715972 A1 EP1715972 A1 EP 1715972A1
Authority
EP
European Patent Office
Prior art keywords
powder
sintered body
diamond
sintering
high hardness
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05721763A
Other languages
German (de)
French (fr)
Inventor
Jeang-Ook Oh
Taek-Jung Shin
Kyu-Hwan Seoul National University OH
Dong-Ik Seoul National University KIM
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Iljin Diamond Co Ltd
Original Assignee
Iljin Diamond Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Iljin Diamond Co Ltd filed Critical Iljin Diamond Co Ltd
Publication of EP1715972A1 publication Critical patent/EP1715972A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B4/00—General methods for preserving meat, sausages, fish or fish products
    • A23B4/03—Drying; Subsequent reconstitution
    • A23B4/031—Apparatus for drying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
    • B01J3/06—Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies
    • B01J3/062—Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies characterised by the composition of the materials to be processed
    • 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
    • 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
    • B22F5/007—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27J—MECHANICAL WORKING OF CANE, CORK, OR SIMILAR MATERIALS
    • B27J1/00—Mechanical working of cane or the like
    • B27J1/003—Joining the cane side by side
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2203/00—Processes utilising sub- or super atmospheric pressure
    • B01J2203/06—High pressure synthesis
    • B01J2203/0605—Composition of the material to be processed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2203/00—Processes utilising sub- or super atmospheric pressure
    • B01J2203/06—High pressure synthesis
    • B01J2203/0605—Composition of the material to be processed
    • B01J2203/062—Diamond
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2203/00—Processes utilising sub- or super atmospheric pressure
    • B01J2203/06—High pressure synthesis
    • B01J2203/0605—Composition of the material to be processed
    • B01J2203/063—Carbides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2203/00—Processes utilising sub- or super atmospheric pressure
    • B01J2203/06—High pressure synthesis
    • B01J2203/0605—Composition of the material to be processed
    • B01J2203/0645—Boronitrides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2203/00—Processes utilising sub- or super atmospheric pressure
    • B01J2203/06—High pressure synthesis
    • B01J2203/065—Composition of the material produced
    • B01J2203/0655—Diamond
    • 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

Definitions

  • the present invention relates to a method for preparing a sintered body having high hardness, in which a hard layer of polycrystalline diamond (hereinafter, referred as
  • the present invention relates to a method for preparing a sintered body having high hardness, wherein the abnormal growth of diamond particles during the sintering process can be suppressed.
  • WC/Co type ultra-hard substrate is widely used as a material for tools.
  • Fig. 1 is a schematic view of illustrating such sintered body with high hardness in conventional arts.
  • a conventional sintered body with high hardness is prepared by: positioning a raw material powder where a diamond powder and a binding powder comprising cobalt as a main ingredient are mixed, on a WC/Co type ultra-hard substrate; and charging the substrate into a fire resistant metal crucible made of a material having a high melting point of 2000 ° C or more, for example Ta, Mo, Nb and the like to sinter it under the conditions of high temperature and high pressure, where diamond is stable.
  • a main binding material of the PCD sintered layer may be those diffused out of the ultra-hard substrate, or cobalt that is contained in the binding powder of the raw material powder.
  • Cobalt is melted under said sintered temperature and pressure condition to form a liquid phase of cobalt, which is served as a catalyst for the PCD forming reaction.
  • the level of activity of diamond in such liquid cobalt becomes very high, therefore the growth and binding reactions of diamond particles, which were diffused into the liquid cobalt, are promoted to finally form a polycrystalline.
  • the crucible is made of a material having a high melting point of 2000 ° C or more, it can be stably maintained without being melted during the PCD sintering process.
  • the method of conventional arts has a problem of abnormal growth of particles near the surface ofthe diamond adjacent to the crucible.
  • the particle growth of diamond is occurred, it is impossible to produce a sintered body thereof having microcrystallines with a targeted particle size.
  • the roughness in the cross-section ofthe material is deteriorated.
  • the particle growth inhibiting materials could be segregated in the PCD layer, which causes a problem of deteriorating the homogeneosity in mechanical characteristics of the sintered body.
  • the particle growth inhibiting materials are minutely milled to the smaller size relative to the diamond powder and mixed in homogenous way, however, the problem of segregation ofthe materials is not completely solved.
  • materials other than cobalt i.e. a binding material are packed into the gap between diamond particles, thereby causing another problem of deteriorating the compactness of sintering.
  • the present invention has been designed to solve those problems of conventional arts.
  • the present invention is to provide a method of preparing a sintered body having high hardness, in which particle growth can be suppressed by using a crucible suppressing the generation of a pool of liquid cobalt, which is the cause of the particle growth.
  • the method of preparing a sintered body with high hardness to achieve said object according to the present invention comprises:
  • a step of preparing a raw material powder for sintering which comprises a diamond powder
  • a step of forming a hard layer of PCD on said ultra-hard substrate by charging the ultra- hard substrate with the raw material powder for sintering into a crucible made of a sintered body comprised of: at least one material selected from a group consisting of catalyst transition metals from Period of 4-6 of Group 4A-6A of Periodic table of elements, and carbides, nitrides and carbo-nitrides thereof and each solid solution thereof; and at least one binding material selected from Fe, Co and Ni, and then carrying out sintering under the conditions of high temperature and high pressure, where diamond is stable.
  • the amount ofthe binding material is 5-30wt% in the crucible composition.
  • the average particle size of the diamond powder is preferably 3 m or less.
  • the raw material powder for sintering preferably comprises a powder of binding material comprised of at least one selected from a group consisting of a catalyst transition metal from Period of 4-6 in Group 3 A ⁇ 7A and Group 8 of Periodic table of elements, and carbides, nitrides, borides and carbo-nitrides thereof and each solid solution thereof.
  • the present inventors have found that the cause of particle growth being occurred around the surface of diamond is based on the formation of a liquid pool of cobalt formed along the wall of a crucible made of a fire resistant metal, wherein the cobalt is melted out from the ultra-hard substrate or the binder. Because the level of activity of the diamond particles is very much increased in the liquid pool of cobalt, it has been thought that diamond particles adjacent to the liquid pool become grow in abnormal way.
  • the liquid pool of cobalt is formed by a phenomenon, so-called 'squeeze out'.
  • 'squeeze out' means that as the diamond particles are getting closer to each other upon the process of sintering, the cobalt component between the diamond particles is squeezed out.
  • the conventional crucible is comprised of a pure metal selected from, for example Mo, Ta, Nb and the like, or alloys thereof, which are stable and compact at sintering temperature, the liquid cobalt which has been squeezed out to the outside starts to form a liquid pool thereof along the wall of the crucible.
  • the present inventors made a research on how to prevent or reduce the liquid pool of cobalt formed along the wall of a crucible. As a result of such investigation, the inventors have found that, when a crucible used for sintering is one being capable of absorbing the liquid pool of cobalt, the squeezed-out liquid cobalt can be absorbed and the particle growth can be prevented.
  • suitable is a crucible made of sintered body comprised of: at least one material selected from a group consisting of catalyst transition metals from Period of 4-6 of Group 4A ⁇ 6A of Periodic table of elements, and carbides, nitrides and carbo- nitrides thereof and each solid solution thereof; and at least one binding material selected from Fe, Co and Ni.
  • a material having a high melting point which is comprised of catalyst transition metals from Period of 4 ⁇ 6 of Group 4A ⁇ 6A of Periodic table of elements, and carbides, nitrides and carbo-nitrides thereof and each solid solution thereof, remains as a solid state without being melted under a PCD sintering condition of 1000 ⁇ 1700°C and 3 ⁇ 10Gpa, and has a function of inhibiting the particle growth.
  • Fe, Co and Ni in the crucible made of a sintered body are materials, which form a isomorphous solid solution with cobalt that is a binding material of the diamond powder and are melted under said sintering conditions.
  • the crucible Before sintering, the crucible has a structure where a material having a high melting point is studded in a binding material having a low melting point, wherein the binding material is intervened between the materials having a high melting point so as to make interconnections between the materials having a high melting point.
  • the binding material component of the crucible is made of at least one of
  • the wall of the cmcible is composed of nearly 100% of cobalt
  • the particles of the material having a high melting point in the binding material are filtrated into the liquid material formed along the wall of the crucible, and the liquid cobalt of the wall of the cmcible flows into the liquid of the binding material in the crucible.
  • the preferred amount ofthe binding material is in the range of 5 ⁇ 30wt%.
  • the characteristic feature of the invention is that the particle growth is inhibited by making an intervention of a material for inhibiting the particle growth or a material for obstructing the formation ofthe liquid cobalt pool only on the area around the surface of the PCD layer where considerable particle growth is mainly occurred, i.e. the area where the liquid cobalt pool is formed, as well as by making the liquid cobalt pool flown to the cmcible direction, being contrary to the conventional methods for inhibiting particle growth by making an intervention of a material for inhibiting particle growth between diamond powders.
  • the present invention is advantageous since it eliminates the problems occurred in prior arts such as segregation of a material for inhibiting particle growth or decrease in sintering compactness.
  • the present invention has special meaning particularly in case of sintering a diamond powder having fine particle size of 3 / an or less.
  • the raw material powder can be comprised of a pure diamond powder without additional powder of a binding material.
  • a binding material usually added to the raw material powder for sintering is a catalyst metal such as Fe, Co, Ni and the like, however, other catalyst metals may be further added to impart other characteristics to the raw material powder.
  • the powder of a binding material may use at least one selected from transition metals from Period of 4-6 of Group 3A-7A and 10 of Periodic table of elements, and carbides, nitrides, borides and carbo-nitrides thereof and each solid solution thereof. Description of Drawings
  • Fig. 1 is a schematic view of illustrating a method for preparing a sintered body according to conventional arts
  • Fig. 2 is a schematic view of illustrating a method for preparing a sintered body according to the present invention
  • Fig. 3 a is an electro-microscopic picture of a sintered body prepared according to a method of conventional arts
  • Fig. 3b is an electro-microscopic picture of a sintered body prepared according to the method ofthe present invention.
  • a powder of a binding material comprising a cobalt powder having 1.5 zm of the average particle size and a WC powder having 0.8 .m of the average particle size was mixed with diamond powders having each 2 ⁇ m and 4/a ⁇ of the average particle size, according to the composition shown in the above table to provide a raw material powder for sintering.
  • the raw material powder for sintering is loaded onto an ultra-hard substrate of WC-8wt% Co, and the resulted substrate with the mixed raw material powder is charged into a cmcible of Wc-6wt% Co and of Ta, respectively. Then they were undergone a sintering process under the condition of 1600°C and 6Gpa for 1 hour by using a belt-type high pressure apparatus.
  • Fig. 3b is a picture showing the cross-section of a sintered body made of a raw material powder for sintering having the composition of specimen A in the above table. As shown in Fig. 3b, it can be recognized that particle growth was hardly occurred. In the meantime, in specimens A and B which were charged into each Ta cmcible, particle growth as much as approximately 100 / a ⁇ or more was seriously occurred. Fig.
  • 3 a is a picture showing the cross-section of a sintered body made of a raw material powder for sintering having the composition of specimen B in the above table, and it can be recognized that particle growth was seriously occurred.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Organic Chemistry (AREA)
  • Forests & Forestry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Wood Science & Technology (AREA)
  • Zoology (AREA)
  • Food Science & Technology (AREA)
  • Polymers & Plastics (AREA)
  • Cutting Tools, Boring Holders, And Turrets (AREA)
  • Powder Metallurgy (AREA)

Abstract

Disclosed is a method of producing a sintered body with high hardness, in which a hard layer of polycrystalline diamond (PCD) is formed on an ultra-hard substrate, which comprises: a step of preparing a raw material powder for sintering, which comprises diamond powder, a step of positioning the raw material powder for sintering onto a WC/Co type ultra-hard substrate; and a step of forming a PCD layer having high hardness on said ultra-hard substrate by charging the ultra-hard substrate with the raw material powder for sintering into a crucible made of a sintered body comprised of: at least one material selected from a group consisting of catalyst transition metals from Period of 4-6 of Group 4A-6A of Periodic table of elements and carbides, nitrides and carbo-nitrides thereof and each solid solution thereof; and at least one binding material selected from Fe, Co and Ni, and then carrying out sintering under the conditions of high temperature and high pressure, where diamond is stable. According to the present invention, it becomes possible to prevent abnormal particle growth of diamond in a PCD layer of a sintered body having high hardness, without adding a powder of a binding material comprising additional materials for inhibiting particle growth, therefore, it is now possible to prepare a sintered body having high hardness, which has excellent machinability and processability.

Description

METHOD OF SINTERING BODY HAVING HIGH HARDNESS
Technical Field
The present invention relates to a method for preparing a sintered body having high hardness, in which a hard layer of polycrystalline diamond (hereinafter, referred as
PCD) is formed on an ultra-hard substrate. Particularly, the present invention relates to a method for preparing a sintered body having high hardness, wherein the abnormal growth of diamond particles during the sintering process can be suppressed.
Background Art A sintered body with high hardness where a hard layer of PCD is formed on a
WC/Co type ultra-hard substrate, is widely used as a material for tools. Fig. 1 is a schematic view of illustrating such sintered body with high hardness in conventional arts.
As illustrated therein, a conventional sintered body with high hardness is prepared by: positioning a raw material powder where a diamond powder and a binding powder comprising cobalt as a main ingredient are mixed, on a WC/Co type ultra-hard substrate; and charging the substrate into a fire resistant metal crucible made of a material having a high melting point of 2000 °C or more, for example Ta, Mo, Nb and the like to sinter it under the conditions of high temperature and high pressure, where diamond is stable. A main binding material of the PCD sintered layer may be those diffused out of the ultra-hard substrate, or cobalt that is contained in the binding powder of the raw material powder. Cobalt is melted under said sintered temperature and pressure condition to form a liquid phase of cobalt, which is served as a catalyst for the PCD forming reaction. Specifically, the level of activity of diamond in such liquid cobalt becomes very high, therefore the growth and binding reactions of diamond particles, which were diffused into the liquid cobalt, are promoted to finally form a polycrystalline.
Disclosure of Invention
Technical Problem
On the other hand, since the crucible is made of a material having a high melting point of 2000 °C or more, it can be stably maintained without being melted during the PCD sintering process.
However, the method of conventional arts has a problem of abnormal growth of particles near the surface ofthe diamond adjacent to the crucible. When the particle growth of diamond is occurred, it is impossible to produce a sintered body thereof having microcrystallines with a targeted particle size. When cutting a material with a tool made of a sintered body in which the abnormal particle growth was occurred, the roughness in the cross-section ofthe material is deteriorated.
Particularly, in case of the abnormal growth of diamond particles as much as 100/rnι or more, there is also a problem such that a wire EDM (Electrical Discharge
Machining) for manufacturing a tool with the sintered body becomes impossible.
In order to prevent such abnormal particle growth of diamond, a sintering method has been proposed, in which carbides, nitrides and borides of a metal selected from Group 4A to 6A of Periodic table of elements, or mixed powder thereof, which inhibit the particle growth of diamond by being positioned on the grain boundary of the diamond particles, are mixed with a diamond powder and sintered together.
However, according to the method, there is a possibility that the particle growth inhibiting materials could be segregated in the PCD layer, which causes a problem of deteriorating the homogeneosity in mechanical characteristics of the sintered body. In order to prevent said problem, in the method, the particle growth inhibiting materials are minutely milled to the smaller size relative to the diamond powder and mixed in homogenous way, however, the problem of segregation ofthe materials is not completely solved.
Additionally, according to said method, materials other than cobalt i.e. a binding material are packed into the gap between diamond particles, thereby causing another problem of deteriorating the compactness of sintering.
Technical Solution
The present invention has been designed to solve those problems of conventional arts. The present invention is to provide a method of preparing a sintered body having high hardness, in which particle growth can be suppressed by using a crucible suppressing the generation of a pool of liquid cobalt, which is the cause of the particle growth.
The method of preparing a sintered body with high hardness to achieve said object according to the present invention comprises:
a step of preparing a raw material powder for sintering, which comprises a diamond powder;
a step of positioning the raw material powder for sintering onto a WC/Co type ultra-hard substrate; and,
a step of forming a hard layer of PCD on said ultra-hard substrate by charging the ultra- hard substrate with the raw material powder for sintering into a crucible made of a sintered body comprised of: at least one material selected from a group consisting of catalyst transition metals from Period of 4-6 of Group 4A-6A of Periodic table of elements, and carbides, nitrides and carbo-nitrides thereof and each solid solution thereof; and at least one binding material selected from Fe, Co and Ni, and then carrying out sintering under the conditions of high temperature and high pressure, where diamond is stable.
The amount ofthe binding material is 5-30wt% in the crucible composition.
Further, the average particle size of the diamond powder is preferably 3 m or less. On the other hand, the raw material powder for sintering preferably comprises a powder of binding material comprised of at least one selected from a group consisting of a catalyst transition metal from Period of 4-6 in Group 3 A~7A and Group 8 of Periodic table of elements, and carbides, nitrides, borides and carbo-nitrides thereof and each solid solution thereof. Hereinafter, the present invention is further described in detail.
As a result of intensive research, the present inventors have found that the cause of particle growth being occurred around the surface of diamond is based on the formation of a liquid pool of cobalt formed along the wall of a crucible made of a fire resistant metal, wherein the cobalt is melted out from the ultra-hard substrate or the binder. Because the level of activity of the diamond particles is very much increased in the liquid pool of cobalt, it has been thought that diamond particles adjacent to the liquid pool become grow in abnormal way.
It is assumed that the liquid pool of cobalt is formed by a phenomenon, so-called 'squeeze out'. The term 'squeeze out' means that as the diamond particles are getting closer to each other upon the process of sintering, the cobalt component between the diamond particles is squeezed out. Since the conventional crucible is comprised of a pure metal selected from, for example Mo, Ta, Nb and the like, or alloys thereof, which are stable and compact at sintering temperature, the liquid cobalt which has been squeezed out to the outside starts to form a liquid pool thereof along the wall of the crucible.
Considering above-mentioned mechanism of particle growth, the present inventors made a research on how to prevent or reduce the liquid pool of cobalt formed along the wall of a crucible. As a result of such investigation, the inventors have found that, when a crucible used for sintering is one being capable of absorbing the liquid pool of cobalt, the squeezed-out liquid cobalt can be absorbed and the particle growth can be prevented.
According to the research ofthe present inventors, it was found that as a crucible having such function, suitable is a crucible made of sintered body comprised of: at least one material selected from a group consisting of catalyst transition metals from Period of 4-6 of Group 4A~6A of Periodic table of elements, and carbides, nitrides and carbo- nitrides thereof and each solid solution thereof; and at least one binding material selected from Fe, Co and Ni.
In the crucible made of a sintered body, a material having a high melting point, which is comprised of catalyst transition metals from Period of 4~6 of Group 4A~6A of Periodic table of elements, and carbides, nitrides and carbo-nitrides thereof and each solid solution thereof, remains as a solid state without being melted under a PCD sintering condition of 1000~1700°C and 3~10Gpa, and has a function of inhibiting the particle growth.
Further, Fe, Co and Ni in the crucible made of a sintered body are materials, which form a isomorphous solid solution with cobalt that is a binding material of the diamond powder and are melted under said sintering conditions.
Before sintering, the crucible has a structure where a material having a high melting point is studded in a binding material having a low melting point, wherein the binding material is intervened between the materials having a high melting point so as to make interconnections between the materials having a high melting point.
The specific mechanism of inhibiting the particle growth ofthe present invention is explained as follows.
When an ultra-hard substrate having a diamond powder or a mixed powder of a diamond powder and a binding material powder on the surface thereof is charged into the cmcible having above-mentioned composition and sintered under the conditions of high temperature and pressure, where diamond is stable, a liquid material of which composition is about 100% cobalt is eluted through the periphery of the crucible wall owing to the squeeze-out.
Since the binding material component of the crucible is made of at least one of
Fe, Co and Ni, all of which have a low melting point, it is melted during the sintering process, and on the other hand, the particles of the material having a high melting point, which remain as a solid form, become suspended in the liquid phase of the binding material.
In an aspect of concentration equilibrium, since the wall of the cmcible is composed of nearly 100% of cobalt, the particles of the material having a high melting point in the binding material are filtrated into the liquid material formed along the wall of the crucible, and the liquid cobalt of the wall of the cmcible flows into the liquid of the binding material in the crucible.
Such process is carried out in nearly simultaneous way, it becomes very difficult that a liquid pool of cobalt, which is so great as to cause abnormal particle growth on the wall ofthe cmcible, is formed. In the meanwhile, when the amount ofthe binding material in the cmcible is less than 5%, the material having a high melting point in the cmcible is changed to an eta- phase thus having a tendency of being brittle, the fluidity of the material having a high melting point is reduced thereby suppressing its transfer to the liquid pool, and therefore it becomes hard to effectively inhibit the formation of the liquid pool. On the other hand, when the amount of the binding material in the cmcible is more than 30wt%, the shape of the cmcible can be collapsed during the sintering process. Therefore, the preferred amount ofthe binding material is in the range of 5~30wt%. The characteristic feature of the invention is that the particle growth is inhibited by making an intervention of a material for inhibiting the particle growth or a material for obstructing the formation ofthe liquid cobalt pool only on the area around the surface of the PCD layer where considerable particle growth is mainly occurred, i.e. the area where the liquid cobalt pool is formed, as well as by making the liquid cobalt pool flown to the cmcible direction, being contrary to the conventional methods for inhibiting particle growth by making an intervention of a material for inhibiting particle growth between diamond powders.
Therefore, the present invention is advantageous since it eliminates the problems occurred in prior arts such as segregation of a material for inhibiting particle growth or decrease in sintering compactness.
In the meanwhile, the smaller the size of the diamond powder is, the more the abnormal growth of diamond particles is greatly occurred. This is because, when the size of diamond becomes smaller, its interfacial surface area contacting with the liquid cobalt becomes larger and thus the surface energy, which is a driving force of particle growth, becomes dramatically increased.
Generally, when the average particle size of a diamond powder raw material is over 3μm, it becomes short ofthe surface energy, and thereby the frequency of occurring abnormal particle growth is significantly decreased. Therefore, the present invention has special meaning particularly in case of sintering a diamond powder having fine particle size of 3 /an or less.
In theory, it is possible to sinter a diamond powder with a cobalt component diffused out ofthe ultra-hard substrate, thus the raw material powder can be comprised of a pure diamond powder without additional powder of a binding material. However, it is common to premix the powder of a binding material into a diamond powder for the structural homogeneity ofthe resulted sintered body.
A binding material usually added to the raw material powder for sintering is a catalyst metal such as Fe, Co, Ni and the like, however, other catalyst metals may be further added to impart other characteristics to the raw material powder. The powder of a binding material may use at least one selected from transition metals from Period of 4-6 of Group 3A-7A and 10 of Periodic table of elements, and carbides, nitrides, borides and carbo-nitrides thereof and each solid solution thereof. Description of Drawings
Fig. 1 is a schematic view of illustrating a method for preparing a sintered body according to conventional arts,
Fig. 2 is a schematic view of illustrating a method for preparing a sintered body according to the present invention,
Fig. 3 a is an electro-microscopic picture of a sintered body prepared according to a method of conventional arts, and
Fig. 3b is an electro-microscopic picture of a sintered body prepared according to the method ofthe present invention.
Best Mode
Hereinafter, preferred embodiments of the present invention are described with referencing the drawings attached to the end of this specification.
EXAMPLES
A powder of a binding material comprising a cobalt powder having 1.5 zm of the average particle size and a WC powder having 0.8 .m of the average particle size was mixed with diamond powders having each 2μm and 4/aτι of the average particle size, according to the composition shown in the above table to provide a raw material powder for sintering. The raw material powder for sintering is loaded onto an ultra-hard substrate of WC-8wt% Co, and the resulted substrate with the mixed raw material powder is charged into a cmcible of Wc-6wt% Co and of Ta, respectively. Then they were undergone a sintering process under the condition of 1600°C and 6Gpa for 1 hour by using a belt-type high pressure apparatus.
The resulted sintered body was subjected to an abrasion process, a polishing process and a wire-cut EDM, and then its cross-section was observed to find that in all of the specimens of the examples according to the present invention, which were charged into the cmcible of WC-6wt% Co, particle growth was hardly occurred. Fig. 3b is a picture showing the cross-section of a sintered body made of a raw material powder for sintering having the composition of specimen A in the above table. As shown in Fig. 3b, it can be recognized that particle growth was hardly occurred. In the meantime, in specimens A and B which were charged into each Ta cmcible, particle growth as much as approximately 100/aτιor more was seriously occurred. Fig. 3 a is a picture showing the cross-section of a sintered body made of a raw material powder for sintering having the composition of specimen B in the above table, and it can be recognized that particle growth was seriously occurred. On the other hand, in the comparative example C where the WC content was
35wt%, particle growth was not occurred, and it is understood that WC blocked the binding of diamond particles and this prevented particle growth.
Further, in the comparative example B, also particle growth was not occurred and it is understood that the average particle size of diamond particles is more than 3μm and the driving force required for particle growth is insufficient to cause serious particle growth.
As described so far, for the examples of the present invention, particle growth was hardly occurred regardless of the composition of a binding material contained in the raw material powder, however for the comparative examples, particle growth was possible to be prevented only when considerable amount of WC was added.
Industrial Applicability
As seen from the above, according to the present invention, it becomes possible to prevent abnormal particle growth of diamond in a PCD layer of a sintered body having high hardness, without adding a powder of a binding material comprising additional materials for inhibiting particle growth, therefore, it is possible to prepare a sintered body having high hardness, which has excellent machinability and processability.

Claims

CLAIMSWhat is claimed is:
1. A method of preparing a sintered body with high hardness, which comprises:
a step of preparing a raw material powder for sintering, which comprises a diamond powder;
a step of positioning the raw material powder for sintering onto a WC/Co type ultra-hard substrate; and,
a step of forming a hard layer of PCD (PolyCrystaline Diamond) on said ultra-hard substrate by charging the ultra-hard substrate with the raw material powder for sintering into a cmcible made of a sintered body comprised of: at least one material selected from a group consisting of catalyst transition metals from Period of 4-6 of Group 4A-6A of Periodic table of elements, and carbides, nitrides and carbo-nitrides thereof and each solid solution thereof; and at least one binding material selected from Fe, Co and Ni, and then carrying out sintering under the conditions of high temperature and high pressure, where diamond is stable.
2. The method of preparing a sintered body with high hardness according to claim 1, characterized in that the amount of the binding material is 5-30wt% in the cmcible composition.
3. The method of preparing a sintered body with high hardness according to claim 1 or 2, characterized in that the average particle size ofthe diamond powder is 3/zm or less.
4. The method of preparing a sintered body with high hardness according to claim 1, characterized in that the raw material powder for sintering comprises a powder of a binding material comprised of at least one selected from a group consisting of catalyst transition metals from Period of 4-6 in Group 3A~7A and Group 8 of Periodic table of elements, and carbides, nitrides, borides and carbo-nitrides thereof and each solid solution thereof.
EP05721763A 2004-01-13 2005-01-11 Method of sintering body having high hardness Withdrawn EP1715972A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020040002148A KR100568970B1 (en) 2004-01-13 2004-01-13 Method of sintering body having high hardness
PCT/KR2005/000079 WO2005068113A1 (en) 2004-01-13 2005-01-11 Method of sintering body having high hardness

Publications (1)

Publication Number Publication Date
EP1715972A1 true EP1715972A1 (en) 2006-11-02

Family

ID=34793234

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05721763A Withdrawn EP1715972A1 (en) 2004-01-13 2005-01-11 Method of sintering body having high hardness

Country Status (3)

Country Link
EP (1) EP1715972A1 (en)
KR (1) KR100568970B1 (en)
WO (1) WO2005068113A1 (en)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101273151B (en) * 2005-08-16 2011-12-28 六号元素（产品）（控股）公司 Fine grained polycrystalline abrasive material
GB0819257D0 (en) * 2008-10-21 2008-11-26 Element Six Holding Gmbh Insert for an attack tool
US8069937B2 (en) * 2009-02-26 2011-12-06 Us Synthetic Corporation Polycrystalline diamond compact including a cemented tungsten carbide substrate that is substantially free of tungsten carbide grains exhibiting abnormal grain growth and applications therefor
US8277722B2 (en) * 2009-09-29 2012-10-02 Baker Hughes Incorporated Production of reduced catalyst PDC via gradient driven reactivity
GB0917670D0 (en) * 2009-10-09 2009-11-25 Element Six Ltd Polycrystalline diamond composite compact element and tools incorporating same
US8505654B2 (en) 2009-10-09 2013-08-13 Element Six Limited Polycrystalline diamond
CN103842067B (en) * 2011-08-23 2016-01-13 六号元素有限公司 There is the thin polycrystalline diamond composite sheet of grain growth inhibitor layer between diamond and base material
CN103602887B (en) * 2013-10-10 2015-11-18 安徽澳德矿山机械设备有限公司 A kind of Powder metallurgy bit matrix and preparation method thereof
CN104493182B (en) * 2014-10-23 2016-06-29 金华中烨超硬材料有限公司 A kind of diamond-Gao vanadium titanium hard alloy glomerocryst composite sheet and preparation method thereof
US10933511B2 (en) 2015-12-27 2021-03-02 Schlumberger Technology Corporation Polycrystalline diamond constructions with modified reaction zone
CN107442776B (en) * 2017-07-12 2019-12-31 东北大学 Method for preparing bimetal composite material by surface liquid phase sintering
CN108284229B (en) * 2018-01-26 2020-04-17 上海工程技术大学 Sintering connection method of nano hard alloy and invar alloy
CN110253024B (en) * 2019-07-22 2021-07-13 吉林大学 Diamond composite sheet containing graphene and preparation method thereof
CN110919004B (en) * 2019-12-04 2022-04-01 武汉玖石超硬材料有限公司 High impact toughness polycrystalline diamond hard alloy composite sheet and manufacturing method thereof
CN111482609B (en) * 2020-06-28 2020-10-13 北京春仑石油技术开发有限公司 Method for manufacturing radial centralizing sliding bearing moving ring

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59563B2 (en) * 1981-10-26 1984-01-07 科学技術庁無機材質研究所長 Manufacturing method of diamond sintered body
DE3583567D1 (en) * 1984-09-08 1991-08-29 Sumitomo Electric Industries SINTERED DIAMOND TOOL BODY AND METHOD FOR PRODUCING IT.
EP0701861B1 (en) * 1994-09-16 2004-11-17 Sumitomo Electric Industries, Ltd. A diamond sintered body and a process for the production of the same, tools and abrasive grains using the same
JPH11240762A (en) * 1998-02-26 1999-09-07 Sumitomo Electric Ind Ltd High-strength, high-abrasion-resistant diamond sintered product and tool therefrom

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005068113A1 *

Also Published As

Publication number Publication date
WO2005068113A1 (en) 2005-07-28
KR100568970B1 (en) 2006-04-07
KR20050073988A (en) 2005-07-18

Similar Documents

Publication Publication Date Title
EP1715972A1 (en) Method of sintering body having high hardness
US5441693A (en) Method of making cemented carbide articles and the resulting articles
CA2281546C (en) Diamond sintered body having high strength and high wear resistance, andtool including the same
US4370149A (en) Diamond compact for a wire drawing die and a process for the production of the same
KR20100067657A (en) Polycrystalline diamond composites
KR20090086999A (en) Polycrystalline diamond abrasive compacts
JP2005239472A (en) High strength and high wear resistance diamond sintered compact and its production method
WO2008053430A1 (en) Polycrystalline diamond abrasive compacts
EP1492897A1 (en) Pre-alloyed bond powders
WO2005068114A1 (en) Method of sintering body having high hardness
CN113059161B (en) Polycrystalline diamond compact and preparation method thereof
JPH0530897B2 (en)
JP2010208942A (en) High strength-high wear resistant diamond sintered body and method of producing the same
CN111321312B (en) In-situ generated tungsten particle reinforced high-entropy alloy-based composite material and preparation method thereof
EP0181979B1 (en) High hardness sintered compact and process for producing the same
WO2020002442A1 (en) Cemented carbide with alternative binder
JPH03115541A (en) Wc-base hard alloy
JPS63286550A (en) Nitrogen-containing titanium carbide-base alloy having excellent resistance to thermal deformation
JP4351453B2 (en) Cemented carbide and drill using the same
JP2004256863A (en) Cemented carbide, production method therefor, and rotary tool using the same
JP5008789B2 (en) Super hard sintered body
JPS63286549A (en) Nitrogen-containing titanium carbide-base sintered alloy having excellent resistance to plastic deformation
JP2017148895A (en) Wc-based cemented carbide drill excellent in breakage resistance
KR100818572B1 (en) High-strength and highly-wear-resistant sintered diamond object and manufacturing method of the same
JP2502322B2 (en) High toughness cermet

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20060814

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE

DAX Request for extension of the european patent (deleted)
RBV Designated contracting states (corrected)

Designated state(s): DE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20090801