U.S. patent application number 11/030160 was filed with the patent office on 2005-07-21 for composite diamond compacts.
This patent application is currently assigned to DE BEERS INDUSTRIAL DIAMONDS (PROPRIETARY) LIMITED. Invention is credited to Tank, Klaus.
Application Number | 20050155295 11/030160 |
Document ID | / |
Family ID | 25588792 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050155295 |
Kind Code |
A1 |
Tank, Klaus |
July 21, 2005 |
Composite diamond compacts
Abstract
A composite diamond compact is provided which has a diamond
compact (12) bonded to a cemented carbide substrate (10). The
composite diamond compact is characterised by the second phase for
the diamond compact (12) and the binder for the cemented carbide
substrate (10) both being a nickel/cobalt alloy.
Inventors: |
Tank, Klaus; (Essexwold,
ZA) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
DE BEERS INDUSTRIAL DIAMONDS
(PROPRIETARY) LIMITED
Johannesburg
ZA
|
Family ID: |
25588792 |
Appl. No.: |
11/030160 |
Filed: |
January 7, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11030160 |
Jan 7, 2005 |
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10297590 |
Jun 3, 2003 |
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10297590 |
Jun 3, 2003 |
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PCT/IB01/01023 |
Jun 13, 2001 |
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Current U.S.
Class: |
51/293 ; 408/145;
428/408; 428/698; 451/28; 451/540; 451/559; 51/295; 51/307;
51/309 |
Current CPC
Class: |
Y10T 428/30 20150115;
C09K 3/1409 20130101; B22F 2005/001 20130101; B22F 7/008 20130101;
B22F 2998/00 20130101; Y10T 408/81 20150115; C22C 26/00 20130101;
B24D 3/06 20130101; Y10T 83/0414 20150401; B22F 2998/00 20130101;
B22F 7/06 20130101 |
Class at
Publication: |
051/293 ;
051/295; 051/307; 051/309; 408/145; 451/540; 451/028; 451/559;
428/408; 428/698 |
International
Class: |
B24D 003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 13, 2000 |
ZA |
2000/2967 |
Claims
1. A composite diamond compact comprising a diamond compact bonded
to a cemented carbide substrate, the diamond compact comprising a
polycrystalline bonded mass of diamond crystals present in an
amount of at least 80 percent by volume of the diamond compact and
a second phase consisting essentially of a nickel/cobalt alloy, the
cemented carbide substrate comprising a mass of carbide particles
bonded into a coherent form by means of a binder consisting
essentially of a nickel/cobalt alloy.
2. The composite diamond compact according to claim 1, wherein the
mass ratio of nickel to cobalt in both of the nickel/cobalt alloys
is in the range 75:25 to 20:80.
3. The composite diamond compact according to claim 1, wherein the
mass ratio of nickel to cobalt in both of the nickel/cobalt alloys
is in the range 30:70 to 45:55.
4. A The composite diamond compact according to claim 1, wherein
the mass ratio of nickel to cobalt in both of the nickel/cobalt
alloys is 40:60.
5. The composite diamond compact according to claim 1, wherein the
carbide particles of the substrate are selected from tungsten
carbide particles, tantalum carbide particles, titanium carbide
particles, molybdenum carbide particles and a mixture containing
two or more of such particles.
6-7. (canceled)
8. The composite diamond compact according to claim 2, wherein the
carbide particles of the substrate are selected from tungsten
carbide particles, tantalum carbide particles, titanium carbide
particles, molybdenum carbide particles and a mixture containing
two or more of such particles.
9. The composite diamond compact according to claim 3, wherein the
carbide particles of the substrate are selected from tungsten
carbide particles, tantalum carbide particles, titanium carbide
particles, molybdenum carbide particles and a mixture containing
two or more of such particles.
10. The composite diamond compact according to claim 4, wherein the
carbide particles of the substrate are selected from tungsten
carbide particles, tantalum carbide particles, titanium carbide
particles, molybdenum carbide particles and a mixture containing
two or more of such particles.
11. A method for cutting comprising: cutting with a composite
diamond compact, wherein the composite diamond compact comprises a
diamond compact bonded to a cemented carbide substrate, the diamond
compact comprising a polycrystalline bonded mass of diamond
crystals present in an amount of at least 80 percent by volume of
the diamond compact and a second phase consisting essentially of a
nickel/cobalt alloy, the cemented carbide substrate comprising a
mass of carbide particles bonded into a coherent form by means of a
binder consisting essentially of a nickel/cobalt alloy; and wherein
said cutting is carried out at a temperature in excess of
500.degree. C. at a cutting edge of the composite diamond
compact.
12. The method according to claim 11, wherein the mass ratio of
nickel to cobalt in both of the nickel/cobalt alloys is in the
range 75:25 to 20:80.
13. The method according to claim 11, wherein the mass ratio of
nickel to cobalt in both of the nickel/cobalt alloys is in the
range 30:70 to 45:55.
14. The method according to claim 11, wherein the mass ratio of
nickel to cobalt in both of the nickel/cobalt alloys is 40:60.
15. The method according to claim 11, wherein the carbide particles
of the substrate are selected from tungsten carbide particles,
tantalum carbide particles, titanium carbide particles, molybdenum
carbide particles and a mixture containing two or more of such
particles.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to composite diamond compacts.
[0002] Diamond compacts, also known as polycrystalline diamond or
PCD, are well known in the art and are used extensively in cutting,
milling, drilling and other abrasive operations. Diamond compacts
are polycrystalline in nature and contain a high diamond content.
Diamond compacts may be produced without the use of a second or
bonding phase, but generally contain such a phase. When such a
phase is present, the dominant component of the phase is generally
a diamond catalyst/solvent such as cobalt, nickel or iron or a
combination thereof.
[0003] Diamond compacts are manufactured under elevated temperature
and pressure conditions, i.e. conditions similar to those which are
used for the synthesis of diamond.
[0004] Diamond compacts tend to be brittle and so in use they are
usually bonded to a substrate, the substrate generally being a
cemented carbide substrate. Bonding of the diamond compact to the
substrate will generally take place during the manufacture of the
compact itself. Diamond compacts bonded to a substrate are known as
composite diamond compacts.
[0005] Composite diamond compacts are used in a variety of
applications and, in particular, in drilling applications. The
bonding phase for such composite diamond compacts is generally
cobalt. Cobalt undergoes a phase transformation at temperatures
above about 400.degree. C. This gives rise to problems in the use
of composite diamond compacts in drilling applications where
temperatures of the order of 700.degree. C. or higher are
encountered at the cutting edge of such compacts. The phase
transformation of the cobalt at these temperatures results in
thermal fatigue craze cracking and snake skin cracking of the
composite compacts during drilling applications.
SUMMARY OF THE INVENTION
[0006] According to the present invention, a composite diamond
compact comprises a diamond compact bonded to a cemented carbide
substrate, the diamond compact comprising a polycrystalline bonded
mass of diamond crystals present in an amount of at least 80
percent by volume of the compact and a second phase consisting
essentially of a nickel/cobalt alloy, and the cemented carbide
substrate comprising a mass of carbide particles bonded into a
coherent form by means of a binder consisting essentially of a
nickel/cobalt alloy.
[0007] Further according to the invention, there is provided the
use of a composite diamond compact as described above in the
abrasive applications where temperatures in excess of 500.degree.
C. are encountered at a cutting edge provided on the compact.
BRIEF DESCRIPTION OF THE DRAWING
[0008] The drawing is a sectional side view of an embodiment of a
composite diamond compact of the invention.
DESCRIPTION OF EMBODIMENTS
[0009] The composite diamond compact of the invention is
characterised by the alloy which is present in the diamond compact
and in the cemented carbide substrate. The alloy in both layers
consists essentially of a nickel/cobalt alloy. This means that the
components of the alloy will consist essentially of nickel and
cobalt with other components being present in trace or minor
amounts only. It has been found that a composite diamond compact of
this nature has a significantly lower tendency to failure through
delamination than prior art composite diamond compacts. Braze
delamination occurs when composite abrasive compacts are brazed
into drill bits. The typical braze alloys used are zinc containing
alloys. Zinc corrosion attack of cobalt binder in the substrate
together with residual stresses in the substrate causes
delamination cracking during the bit brazing process. Further, the
presence of nickel increases significantly the thermal fatigue
resistance of the compact and reduces the tendency for snake skin
cracking to occur during operations such as drilling where
temperatures of the order of 700.degree. C. or higher are
encountered.
[0010] Thus, the invention also provides the use of a composite
abrasive compact in abrasive applications where temperatures in
excess of 500.degree. C. are encountered at a cutting edge of the
compact. The cutting edge will generally be provided by the
peripheral edge of the diamond compact. The abrasive applications
may be cutting, drilling, milling or the like.
[0011] A mass ratio of nickel to cobalt in the alloy will generally
range from 75:25 to 20:80 and preferably in the range 30:70 to
45:55. A typical example of an alloy is one containing a mass ratio
of nickel to cobalt of 40:60. The carbide particles of the
substrate may be tungsten carbide particles, tantalum carbide
particles, titanium carbide particles, molybdenum carbide particles
or a mixture containing two or more of such particles.
[0012] The composite diamond compact of the invention may be made
by methods known in the art. More particularly, a mass of diamond
particles may be placed on a surface of a cemented carbide
substrate forming an unbonded assembly which is then subjected to
diamond synthesis conditions. The alloy from the substrate
infiltrates the diamond mass forming a diamond compact which bonds
to the substrate. In one preferred form of the invention, a recess
is formed in the cemented carbide substrate and the mass of diamond
particles is placed in the recess. After formation of the diamond
compact, the sides of the substrate may be removed to expose the
diamond compact. The diamond synthesis conditions will typically be
a pressure of 40 to 70 kilobars (4 to 7 GPa) and a temperature of
1300 to 1600.degree. C. These conditions will typically be
maintained for a period of 20 to 60 minutes.
[0013] An embodiment of the invention will now be described. A
cylindrical cemented carbide substrate was provided. The substrate
comprised a mass of tungsten carbide particles bonded into a
coherent form by means of a nickel/cobalt alloy. The mass ratio of
the nickel to cobalt in the alloy was 40:60.
[0014] A recess was formed in one flat end surface of the
substrate. A mass of diamond particles was placed in the recess and
filled the recess. This unbonded assembly was placed in the
reaction zone of a conventional high temperature/high pressure
apparatus and subjected to a temperature of about 1500.degree. C.
and a pressure of about 55 kilobars (5,5 GPa). These conditions
were maintained for a period sufficient to produce a diamond
compact of the diamond particles. During the formation of the
compact, nickel/cobalt alloy from the substrate infiltrated the
diamond mass and formed a second phase for the diamond compact. The
diamond compact was bonded to the cemented carbide body.
[0015] The resulting product was removed from the apparatus and the
sides of the cemented carbide substrate removed. The resulting
product is illustrated by the accompanying drawing and consisted of
a diamond compact 12 bonded to a cemented carbide substrate 10
along interface 14. The diamond compact 12 had a second phase
consisting essentially of a nickel/cobalt alloy and the cemented
carbide substrate 10 had a binder consisting essentially of the
same alloy. The diamond compact 12 has an upper working surface 16
and a peripheral cutting edge 18.
[0016] The composite abrasive compact illustrated by the drawing
may be used as a drill insert. In use, the cutting edge 18 performs
a cutting action in drilling and in hard rocks temperatures in
excess of 500.degree. C. are encountered. Due to the presence of
the nickel/cobalt alloy in both the diamond compact and in the
cemented carbide substrate, the thermal fatigue resistance of the
composite compact is increased and there is reduction in the
tendency for snake skin cracking to occur, as is a common problem
with prior art composite compacts using cobalt as the binder
alloy.
* * * * *