U.S. patent number 3,879,901 [Application Number 05/395,457] was granted by the patent office on 1975-04-29 for metal-coated diamonds in a metal alloy matrix.
This patent grant is currently assigned to De Beers Industrial Diamond Division Limited. Invention is credited to Robert John Caveney.
United States Patent |
3,879,901 |
Caveney |
April 29, 1975 |
Metal-coated diamonds in a metal alloy matrix
Abstract
A compact comprising substantially graphite-free diamond
particles having a continuous coating of titanium or molybdenum
held in a matrix into which the titanium or molybdenum can diffuse.
The matrix may for example, be an alloy selected from the group of
Fe/Ni, Ni/Co/Cr/Fe, Fe/Si and Ti/Si alloys. The invention also
provides a method of making such a compact by mixing the desired
metal powders in suitable proportions with the coated diamond
particles and compacting the mixture under pressure and temperature
conditions in the diamond stable zone.
Inventors: |
Caveney; Robert John
(Johannesburg, ZA) |
Assignee: |
De Beers Industrial Diamond
Division Limited (Johannesburg, ZA)
|
Family
ID: |
27387381 |
Appl.
No.: |
05/395,457 |
Filed: |
September 10, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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153105 |
Jun 14, 1971 |
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Foreign Application Priority Data
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Jun 24, 1970 [ZA] |
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70/4347 |
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Current U.S.
Class: |
51/295;
51/309 |
Current CPC
Class: |
C22C
26/00 (20130101); B01J 3/062 (20130101); C09K
3/1445 (20130101); B01J 2203/066 (20130101); B01J
2203/0655 (20130101); B01J 2203/0685 (20130101); B01J
2203/062 (20130101) |
Current International
Class: |
C22C
26/00 (20060101); B01J 3/06 (20060101); C09K
3/14 (20060101); B24d 003/06 () |
Field of
Search: |
;51/295,309 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Arnold; Donald J.
Attorney, Agent or Firm: Young & Thompson
Parent Case Text
This is a continuation of application Ser. No. 153,105, filed June
14, 1971, and now abandoned.
Claims
We claim:
1. A compact consisting essentially of substantially graphite-free
diamond particles having a continuous metal coating of thickness
from 1,000 to 2,000A chemically bonded thereto and held in a matrix
by a diffusion alloy of the metal and the matrix at the
metal/matrix interface, the metal being selected from the group
consisting of titanium and molybdenum and the matrix being selected
from the group consisting of Fe/Ni, Ni/Co/Cr/Fe and Fe/Si alloys
and WC bonded with a transition metal of the VIII group, said
compact having a grinding efficiency ratio greater than 1.
2. A compact according to claim 1, wherein the matrix is an Fe/Ni
alloy the ratio of iron to nickel in the alloy being 12/5.
3. A compact according to claim 1, wherein the matrix is a
Ni/Co/Cr/Fe alloy, the ratio of the metals in the alloy being
34/18/14/5.
4. A compact according to claim 1 wherein the matrix is an Fe/Si
alloy the ratio of the iron to the silicon in the alloy being
63/2.
5. A compact according to claim 1 wherein the matrix is WC bonded
with cobalt which is present in the amount of about 10 percent by
weight of the WC.
Description
This invention relates to compacts and it is an object of the
present invention to provide a compact having improved properties
over compacts of the prior art.
According to the invention there is provided a compact comprising
substantially graphite-free diamond particles having a continuous
coating of titanium or molybdenum held in a matrix compatible with
the titanium or molybdenum coating. The term compatible means that
the matrix must be such as allow diffusion of the titanium or
molybdenum into it.
The matrix may be an alloy selected from the group of Fe/Ni,
Ni/Co/Cr/Fe, Fe/Si, Ti/Si, Ti/Ni and Ti/Fe alloys, but is
preferably one of the following alloys: Ni/Co/Cr/Fe:: 34/18/14/5
Fe/Ni:: 12/5 Fe/Si:: 63/2
All the above-mentioned ratios are weight for weight.
The matrix may also advantageously be tungsten carbide bonded with
a transition metal of the 8th group, preferably cobalt. The
transition metal is preferably present in the amount of about 10
percent by weight of the tungsten carbide.
The thickness of the titanium or molybdenum coat would normally be
of the order of 1,000 to 2,000 A, but coats of greater thickness
can also be used.
The titanium or molybdenum coated diamonds for use in the compacts
may be prepared by methods known to the art. The coating may, for
example, be deposited on to the diamond surface by the method of
vacuum deposition described in "Vacuum Deposition of Thin Films" by
L. Holland, Chapman and Hall, 1st Edition 1956. In order to create
a titanium/diamond or molybdenum/diamond bond, as the case may be,
the coated diamond may be heated to a temperature of greater then
500.degree.C to form the desired bond. However, this heating is not
necessary as the during compact manufacture temperatures above
500.degree.C are encountered and the bond formation can therefore
be obtained during the compact manufacture.
Further according to the invention, there is provided a method of
making a compact including the steps mixing diamond particles
having a continuous coating of titanium or molybdenum with a matrix
material suitable to provide, on compaction, a matrix compatible
with the titanium or molybdenum coating of the particles and
compacting the mixture under pressure and temperature conditions in
the diamond stable zone.
The diamond stable zone is a set of conditions known to the art and
the Applicant refers to Berman R, and Simon F, Z. Elektrochem, Vol
59, 1955 page 333 in this regard.
Preferably, the pressure during compaction is about 60 kilobars and
the temperature is between about 1,200.degree. and
1,400.degree.C.
Embodiments of the invention will now be described.
Diamond compacts having a variety of matrices were prepared in the
following manner:
In all cases, diamond grit having a continuous titanium or
molybdenum coating and the metal powders necessary to make the
desired alloy were weighed into a plastic bottle. If for example,
an iron/nickel alloy (12:5) was desired then 12 parts by weight of
iron powder and 5 parts by weight of nickel powder were weighed
into the bottle. The metal powders and grit were then mixed by
placing the bottle in a milling machine for about 20 minutes. The
mixture was placed in a graphite mould and loaded into a standard
synthesis capsule. If the synthesis volume was not completely
filled by the mould, compacted graphite was added to the capsule to
fill the balance of the volume.
The mixture was then subjected to compaction for about five minutes
at a pressure of about 60 kilobars and a temperature of between
1,200.degree. and 1,400.degree.C. These temperatures and pressures
are in the diamond stable zone.
Using the above-mentioned method a number of diamond compacts were
manufactured. Table I below sets out the diamond grit particle size
and the matrix material used in these compacts.
TABLE I ______________________________________ Compact Diamond
Particle Matrix Size (mesh) ______________________________________
1 60/80 Fe/Ni::12/5 2 140/170 Fe/Ni::12/5 3 - 325 Fe/Ni::12/5 4
60/80 WC -- 10% Co. 5 140/170 Ti/Ni::37/6 6 60/80 Cu/Al::65/5 7
60/80 Fe/Si::6.3/2 8 140/170 Fe/Si::63/2 9 60/80 Ti/Si::34/3 10
140/170 Ni/Co/Cr/Fe::34/18 14/5 11 140/170 Ti/Fe::31/15
______________________________________
In all the above cases, the diamond content of the compacts was 65%
Vol/Vol.
The above mentioned compacts were compared in properties with a
compact comprising uncoated diamond grit in a titanium-silicon
matrix and it was found on an average that the grinding efficiency
ratios of the invented compacts were greater than 1. The efficiency
ratio is the ratio of wear under a set of abrading conditions of
the invented compact to the wear under the same set of conditions
of the standard compact times a conversion factor. The conversion
factor reflects the differing densities of the matrices.
A value of greater than 1 indicates that the invented compact has
superior abrasion resistance to the standard compact. Of the
results, the most significant were those obtained for the compacts
having Fe/Ni, WC bonded with 10% Co, Ni/Co/Cr/Fe, and Fe/Si
matrices where the efficiency ratios were found to be 1.59, 4.53,
3.79 and 1.50, respectively.
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