Doping Fe-based diamond tool matrix composites with a rare-earth element
The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is...
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| Cite this: | Doping Fe-based diamond tool matrix composites with a rare-earth element / Q. Zou, W. Gong, X. Zeng, Y. Wu, J. Liu, Sh. Zou // Сверхтвердые материалы. — 2009. — № 6. — С. 67-74. — Бібліогр.: 3 назв. — англ. |
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Zou, Q. Gong, W. Zeng, X. Wu, Y. Liu, J. Zou, Sh. 2014-06-01T15:10:58Z 2014-06-01T15:10:58Z 2009 Doping Fe-based diamond tool matrix composites with a rare-earth element / Q. Zou, W. Gong, X. Zeng, Y. Wu, J. Liu, Sh. Zou // Сверхтвердые материалы. — 2009. — № 6. — С. 67-74. — Бібліогр.: 3 назв. — англ. 0203-3119 https://nasplib.isofts.kiev.ua/handle/123456789/63427 66.046.51:661.865.5:621.9.025.7 The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is indicated. The performance of matrix composites with and without rare-earth elements has been assessed. The results obtained show that the flexural strength, the hardness, and the impact ductility of matrix composites with rare-earth elements have been improved. The flexural strength and the impact ductility increased correspondently by 10—62 % and about 5 %, as compared to composites free of rare-earth elements. Rare-earth diamond tool matrix composites where Co was replaced with Fe, which provides a good practical service performanc, and a low price, have been successfully studied, corresponding diamond bits and saw blades have been manufactured. en Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України Сверхтвердые материалы Инструмент, порошки, пасты Doping Fe-based diamond tool matrix composites with a rare-earth element Article published earlier |
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Doping Fe-based diamond tool matrix composites with a rare-earth element |
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Doping Fe-based diamond tool matrix composites with a rare-earth element Zou, Q. Gong, W. Zeng, X. Wu, Y. Liu, J. Zou, Sh. Инструмент, порошки, пасты |
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Doping Fe-based diamond tool matrix composites with a rare-earth element |
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Doping Fe-based diamond tool matrix composites with a rare-earth element |
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Doping Fe-based diamond tool matrix composites with a rare-earth element |
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Doping Fe-based diamond tool matrix composites with a rare-earth element |
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doping fe-based diamond tool matrix composites with a rare-earth element |
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Zou, Q. Gong, W. Zeng, X. Wu, Y. Liu, J. Zou, Sh. |
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Zou, Q. Gong, W. Zeng, X. Wu, Y. Liu, J. Zou, Sh. |
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Инструмент, порошки, пасты |
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Инструмент, порошки, пасты |
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2009 |
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Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України |
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The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is indicated. The performance of matrix composites with and without rare-earth elements has been assessed. The results obtained show that the flexural strength, the hardness, and the impact ductility of matrix composites with rare-earth elements have been improved. The flexural strength and the impact ductility increased correspondently by 10—62 % and about 5 %, as compared to composites free of rare-earth elements. Rare-earth diamond tool matrix composites where Co was replaced with Fe, which provides a good practical service performanc, and a low price, have been successfully studied, corresponding diamond bits and saw blades have been manufactured.
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Doping Fe-based diamond tool matrix composites with a rare-earth element / Q. Zou, W. Gong, X. Zeng, Y. Wu, J. Liu, Sh. Zou // Сверхтвердые материалы. — 2009. — № 6. — С. 67-74. — Бібліогр.: 3 назв. — англ. |
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2025-11-25T00:50:28Z |
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ISSN 0203-3119. Сверхтвердые материалы, 2009, № 6 67
Инструмент, порошки, пасты
UDC 66.046.51:661.865.5:621.9.025.7
Q. Zou, W. Gong, X. Zeng, Y. Wu, J. Liu,
Sh. Zou (Wuhan, Hubei, P. R. China)
Doping Fe-based diamond tool matrix
composites with a rare-earth element
The paper presents the experiments on adding rare-earth element
cerium to diamond matrix composites. Based on the doping of rare earth in metal
powders including tungsten carbide, a small amount of nickel, iron entirely replacing
cobalt in diamond matrix and the process route of rare earth doping is indicated. The
performance of matrix composites with and without rare-earth elements has been
assessed. The results obtained show that the flexural strength, the hardness, and the
impact ductility of matrix composites with rare-earth elements have been improved.
The flexural strength and the impact ductility increased correspondently by 10—62 %
and about 5 %, as compared to composites free of rare-earth elements.
Rare-earth diamond tool matrix composites where Co was replaced with Fe, which
provides a good practical service performanc, and a low price, have been successfully
studied, corresponding diamond bits and saw blades have been manufactured.
Key words: doping cerium, matrix materials, flexural strength,
impact ductility, metallized diamond tools.
Introduction
Hot-pressed diamond tool composites are composed of diamond
particles and the matrix, which includes cemented carbide bonded powder with
WC as a framework, bronze-bonded powder with 663Cu as the main component,
Co-based bonded powder with Co—Ni as the main constituent [1—3], etc. Taken
together, these components constitute the most common matrix formulation of hot-
pressed diamond tool composites. This reseach has mainly involved the preparation
of Fe-based bonded powder doped with rare-earth cerium as an important point [1,
2], the study of doping rare-earth cerium and the replacement of the expensive Co-
based bonded powder in the above matrix formulation. Since the amount of the
rare-earth additive is quite small, generally below 1 % of the gross amount of a
binding agent, the cost of Fe-based diamond tool composites with the rare earth is
very low.
No matter how to add the rare earth and in what form, one of the main purposes
is to ensure the uniform diffusibility and catalytic activity of the rare-earth material
in carbide, so as to ensure the stability of the performance of diamond tool compos-
ites under the action of the rare earth.
© Q. ZOU, W. GONG, X. ZENG, Y. WU, J. LIU, SH. ZOU, 2009
www.ism.kiev.ua; www.rql.kiev.ua/almaz_j 68
When a rare-earth element is directly added with rare-earth oxides, rare-earth
pure metal powder, rare-earth hydride, rare-earth nitride, and rare-earth salt, it is
difficult to ensure its uniform diffusibility and catalytic activity, with the result that
it is also difficult to ensure the stability of the performance of the diamond tool
composites, so both the adding mode and technique have been rejected. Mean-
while, although the alloy powder can be directly added to the rare-earth and its
uniform diffusibility can be ensured, it is easy to meet with oxidation and the price
is relatively high, therefore, it is also not perfect.
In view of these factors, the study involved experiments on rare-earth doping
technique of diamond tool (matrix) composites by means of the improved doping
technique.
Experimental
Doping technique. One of the purposes of doping technique is to make the rare-
earth element evenly dispersed in the mixture with the aim to obtain the uniform
catalytic action and activation. One rare-earth element available in the market is
hydrous rare-earth chloride. The heating, dehydration and thermal decomposition
of hydrous rare-earth chloride are carried out by the hot pressing technique after
doping to get anhydrous rare-earth chloride CeCl3 and rare-earth sesquioxide
Ce2O3. In experiments it was shown that CeCl3 and Ce2O3 have relatively strong
catalytic and activating characteristics.
RE Cl
3
solution WC/mixed powder with iron
Doping
Drying at 100 °C
TiH
2
reduction
WC/mixed powder + RE/(RE salt)
RE Cl
3
organic solvent solution WC/mixed powder with iron
Doping and soaking
Drying at 30—40 °C
TiH
2
reduction
WC/mixed powder + RE/(RE salt)
B. Improved doping
A. Conventional doping
Fig. 1. Process chart of getting composite powders with dispersed RE/RE salt by doping.
ISSN 0203-3119. Сверхтвердые материалы, 2009, № 6 69
The dehydration and thermal decomposition of CeCl3 · 7H2O [1]:
CeCl3 · 7H2O = H2O + CeCl3 · 6H2O = 3H2O+ CeCl3 · 3H2O =
= 2H2O + CeCl3 · H2O → CeCl3 → CeOCl → Ce2O3.
It can be seen from the above processes of dehydration and thermal
decomposition of rare-earth chloride (CeCl3) that the latter plays the role of
catalytic action and activation twice in the doping technique of rare-earth chloride
(CeCl3): one is catalytic action and activation of CeCl3 as Lewis acid and the other
is the one of rare-earth sesquioxide Ce2O3 obtained when heated to a relatively
high temperature.
In the doping process, if temperatures of drying and heating of the doped pow-
der of rare-earth chloride are too high, the active rare-earth chloride may only react
with a part of doped metal powder (WC, Ni, 663Cu, Fe, etc.) to produce rare-earth
metal composite oxides (such as the composite oxides of rare earth and W,
LnNiO3, Ln2CuO4, etc.), in this way, there is no sufficient rare-earth oxide (Ce2O3)
to generate the activity of the above rare-earth metal composite oxides in subse-
quent hot pressing and agglomeration processes.
Therefore, the temperature for thermal decomposition of rare-earth chloride to
prepare the oxides should not be too high. Figure 1 is the process chart of preparing
the rare-earth matrix composites by doping.
In experiments it haz been shown that it is possible to effectively improve the
activity of doping powder by means of reduction treatment of rare-earth (Ce) dop-
ing powder with TiH2 powder (see Fig. 2).
20 30 40 50 60 70 2θ, deg
D
if
fr
ac
ti
on
in
te
ns
it
y
2.5
5.0
0
C
e
(1
11
)
C
e
(2
00
)
C
e
(2
20
)
C
e
(3
11
)
C
e
(2
22
)
C
e
(4
00
)
Fig. 2. X ray spectrum of Ce obtained by reduction treatment with TiH2 after doping WC with
CeCl3.
Improvement of doping technique. This study has made an important
improvement in doping technique. The most serious problems encountered in dop-
ing technique are:
— After doping, the dried powder of a metal alloy easily forms a very hard
small particle block which is easy to meet with oxidation, seriously affecting the
grain size and quality of the powder and the doping effect of uniform diffusibility
to which the doping rare earth should reach up. If various rare-earth salts, rare-
earth oxides, and rare-earth chlorides are diluted with water, as the doping rare-
earth diluent, and then doped, they will easily meet with the above-mentioned
harmful consequences.
www.ism.kiev.ua; www.rql.kiev.ua/almaz_j 70
— In case of direct doping with rare-earth chloride, it is still not easy to realize
the doping effect of uniform diffusibility with the result that the stability of the
service performance of doped matrix composites and Fe-based diamond tool
composites doped with a rare earth will not be ensured effectively.
— The surface oxidation of the powder caused by improper operation of doping
technique, the rare earth and the metal that have not been completely reduced, etc.
included in the diamond tool composites, will show up as microcracks and pores in
the oxide layer, which will impair the hot-pressed plasticity and compactness of
diamond tool composites.
— After doping with rare-earth nitric acid solution, the nitrate ions can only be
removed after being heated to a considerably high temperature. Hot-pressed ag-
glomeration is generally made at 900 °C and the service performance of diamond
tool composites may drop sharply if the nitrate ions cannot be removed effectively
at this temperature.
After improvement, the doping technique has put special emphasis on
improving the doping process using rare-earth chloride (CeCl3, CeCl2) with organic
substances, meanwhile, reduction treatment has been carried out by adding TiH2 in
different adding manners and in different amounts. The corresponding optimizing
experiments have been made and a relatively good reduction effect (see Fig. 2) has
been obtained, the service performance, stability and repeatability of the Fe-based
powder matrix composites doped with the rare earth have been improved greatly.
Testing of the diamond matrix service performance. General. The study
involved hot-pressed agglomeration processing of diamond tool (matrix)
composites with the rare earth by the doping method, the related service
performance tests, and compared the test results for diamond tool (matrix)
composites with the rare earth with those for composites free of the rare earth. The
results have shown that the service performance of the Fe-based diamond tool
(matrix) composites with the rare earth is obviously higher than that of the Fe-
based diamond tool (matrix) composites free of rare-earth doping, the repeatability
and stability of the experiment have reached a higher level [1, 2].
Main indexes of performance tests include bending strength, hardness, impact
toughness and porosity, among which the bending strength is the most important.
The tests may be carried out in three steps: the first step is the evaluation of the
performance of the composite material of the matrix; the second step is that of
bonded and uncoated diamond tool composites for matrix; the third step is that of
bonded and coated diamond tool composites for matrix.
Raw materials, equipment, and the method of experiment.
– Raw materials.
Raw materials used for the experiment include: standard WC powder (grain size
of 40 μm), Co powder (grain size of 50 μm), rare-earth Ce, uncoated diamond and
diamond with vacuum deposited W (grain size of 250 μm), 663Cu powder, pure
Fe, Ni, Mn, Co, TiH2 powder, etc. (grain size of 50 μm).
– Preparation of the materials.
After doping, the rare earth is dried in vacuum at 90 °C in a dry box. The
diamond, powder material of the matrix, and hexane are put in a ball grinding pot.
This study involves two matrix formulations. The first one: take 663Cu as a
binder phase of the liquid phase for matrix composites and mix it with 35 % pure
Fe (or pure Co) and 15 % WC, the rest being Ni, Mn, and TiH2 powders, etc. The
second one: take 663Cu as a binder phase of the liquid phase for matrix composites
ISSN 0203-3119. Сверхтвердые материалы, 2009, № 6 71
and mix it with 3—5 % pure Fe (or pure Co) and 35 % WC, the rest being Ni, Mn,
and TiH2 powders, etc.
Carry out the ball milling tempering of the above formulations with and without
rare-earth elements (RE = 0) separately. Weight ratio of ball materials is 1:2. Mill
the material in a ball mill for 12 h and load the mixed powdered material into a
graphite die. Sintering conditions are: temperature — 1000 °C, holding time —
2—3 min, sintering pressure — 50—60 MPa.
– Sintering equipment: an intermediate frequency induction sintering furnace
with the heating power of 100 kW, intermediate frequency of 1 kHz, a noncontact
optical fiber temperature meter bearing a measuring scope of 600—1200 °C, and
an open-sided press bearing a tonnage of 40 t.
Performance testing of the diamond matrix. The bending strength of the
specimen was tested by the three-point bending method. The size of the specimen
was b×h×l = 8×7×40 mm and the calculation formula of the cross-breaking
strength was Rtr = 3PL/2b2h (MPa), where P is the breaking load, b and h are the
width and the height of the specimen, respectively, L is the distance between sup-
porting points and equals 24 mm in the actual measurement. The hardness of the
specimen was tested on the Rockwell hardness tester. Refer to Tables 1 and 2 for
the test results.
The room-temperature impact testing of the specimen was carried out on the
impact tester; the bearing line space of the specimen was 30 mm. Refer to Table 3
for the test results.
Testing of diamond tool. Use coated diamond, add the rare earth to the matrix,
manufacture diamond tools (a bit and a saw blade) by the hot-press sintering
method, then test the bit on an indoor micro-drilling test bench and carry out the
test of productive cutting of granite. The test and the analysis of its technical
characteristics are described in [1].
Microdrilling with diamond bits. A number of bits 25 mm in diameter, RMB
55/piece, with coated diamond and the matrix formulation with the rare earth and
bits 25 mm in diameter, RMB 56.2/piece, with uncoated diamond and the matrix
formulation free of the rare earth have been manufactured by hot-press sintering
and tested in drilling in marble and granite on a microdrilling test bench. See Table
4 for drilling results.
Production testing of diamond saw blades. By means of hot-press sintering, two
blades 350 mm in diameter have been manufactured using coated diamond and the
matrix formulation with the rare earth and two blades 350 mm in diameter have
been manufactured using uncoated diamond and the matrix formulation free of the
rare earth. Cutting tests have been carried out on two kinds of granite. See Table 5
for the test results.
Results and analysis
Analysis of the experimental results. Refer to Tables 1—5 for the test results.
It can be seen from Table 1 that the average bending strength of the 35 % Fe-
based matrix with the rare earth has improved at least by 10 % as compared to that
free of the rare earth (samples 1 and 2 for comparison) and by 62 % (samples 1 and
5 for comparison) at most. The hardness has also improved to a certain extent.
Tables 1 and 2 show that the bending strength and hardness of 35 % Fe-based ma-
trix with the rare earth are close to those of 35 % Fe-based matrix free of the rare
earth (samples 5 and 6 and samples 15 and 16 for comparison).
www.ism.kiev.ua; www.rql.kiev.ua/almaz_j 72
Table 1. Average bending strength and hardness of 35 % Fe-based*
(35 % Co-based) pure matrix with and without the rare-earth element
Sample Type, wt %
Average bending strength,
MPa
Average hardness
HRB
1 RE = 0, 35 % Fe-based 534.30 82.37
2 Ce = 0.2, 35 % Fe-based 585.58 85.49
3 Ce = 0.5, 35 % Fe-based 782.42 92.85
4 Ce = 0.7, 35 % Fe-based 800.10 93.16
5 Ce = 0.3, 35 % Fe-based 864.65 94.35
6 RE = 0, 35 % Co-based 971.37 96.24
* 35 % Fe = 35 % Fe + (18—25) % WC + 35 % 663Cu + (5—10) % Ni + 1 % P,
35 % Co = 35 % Co + (18—25) % WC + 35 % 663Cu + (5—10) % Ni + 1 % P.
Samples in 30×8×8 mm size.
Table 2. Average bending strength and hardness of 35 % Fe-based
(35 % Co-based) diamond matrix with and without the rare-earth element
Sample Type, wt %
Average
bending
strength, MPa
Average
hardness
HRB
10 RE = 0, 35 % Fe-based with uncoated diamond 522.36 92.53
11 RE = 0, 35 % Fe-based with coated diamond 529.61 92.46
12 Ce = 0.3 %, 35 % Fe-based with uncoated diamond 562.52 93.78
13 Ce = 0.3 %, 35 % Fe-based with coated diamond 587.38 94.52
14 Ce = 0.3 %, 35 % Fe-based with uncoated diamond 585.12 93.89
15 Ce = 0.3 %, 35 % Fe-based with coated diamond 596.87 96.21
16 RE = 0, 35 % Co-based with coated diamond 590.83 94.58
It is seen from Table 2 that the bending strength of bonded and coated diamond
matrix is universally higher than that of bonded and uncoated diamond matrix. The
bending strength of the matrix with the rare earth has been improved by 10 % as
compared to that of the matrix free of the rare earth (bonded diamond), the
hardness has also been slightly improved. Furthermore, the performance of Fe-
based diamond matrix with the rare earth was quite close to and even exceeded the
performance of the similar Co-based diamond matrix (free of the rare earth).
Table 3. Average impact toughness of 35 % Fe-based diamond matrix
at room temperature with and without the rare-earth element
Sample
with the rare
earth
Cross
sectional
area F0, cm2
Ak, J
Impact
toughness
ak, J⋅cm–2
Sample
free of the
rare earth
Cross
sectional
area F0,
cm2
Ak, J
Impact
toughness
ak, J⋅cm–2
1 0.624 5.9 9.46 4 0.6806 4.3 6.32
2 0.6557 2.3 4.17 5 0.648 2.7 3.51
3 0.6399 2.3 3.59 6 0.6478 2.3 3.56
ISSN 0203-3119. Сверхтвердые материалы, 2009, № 6 73
Refer to Table 3 for the results of the impact toughness of 35 % Fe-based
bonded diamond matrix at room temperature with and without the rare-earth
element.
Table 3 shows that the average impact toughness of the sample with the rare
earth is about 5 % higher than that of the one without the rare earth.
Table 4. Drilling characteristics of diamond bits of different types
Drilling rate Bit life Cost Rock Bit type
m/h–1 ratio, % m ratio, % YUAN/m–1 ratio, %
Coated, with
the rare earth
6.12 1.02 30.7 1.17 1.83 1.00 Marble
Uncoated, without
the rare earth
6.0 1.00 26.2 1.00 2.09 1.14
Coated, with
the rare earth
4.51 1.07 25.8 1.19 2.18 1.00 Granite
Uncoated, without
the rare earth
4.21 1.00 21.6 1.00 2.55 1.17
Note: the cost “YUAN” in the table is in RMB.
It can be seen from Table 4 that the technical and economical characteristics of
the coated diamond bit with the rare earth are higher than those of the uncoated
diamond bit free of the rare earth, the drilling rate has been raised by 2—7 %, the
service life of the bit has been prolonged by 17—19 %, and the cost has been re-
duced by 14—17 % when drilling marble and granite.
Table 5. Experimental results of cutting granite with a diamond saw blade
Saw blade life Diamond efficiency
Rock
Saw blade
type
Dose
of diamond,
mg m2 ratio % m2⋅mg–1 ratio %
Electric
current, A
Uncoated,
without the rare
earth
7680 62.0 1.00 0.00487 1.00 11.6 635 type
granite
Coated, with
the rare earth
7680 76.5 1.23 0.00592 1.24 10.5
Uncoated,
without the rare
earth
8640 37.4 1.00 0.00433 1.00 12.5 605 type
granite
Coated, with
the rare earth
8640 45.5 1.22 0.00527 1.21 11.2
It is seen From Table 5 that the service life of the coated diamond saw blade
with the rare earth has been increased by 22 % and the utilization ratio of diamond
has been increased by 22 % compared with the uncoated diamond saw blade free
of the rare earth. Meanwhile, it should be pointed out that the sawing current
strength is related to the consumption of power, which can also explain the cutting
efficiency and the degree of sharpness of the saw blade. Therefore, it is deemed
that the cutting efficiency of the bonded and coated diamond saw blade with the
rare-earth matrix is higher and the saw blade is sharper.
www.ism.kiev.ua; www.rql.kiev.ua/almaz_j 74
Conclusions
The paper deals with diamond tool (matrix) composites, in which Co is re-
placed with Fe, and mainly with the doping technique with rare-earth chloride. The
doping method has a simple technique, low cost, good repeatability and stability.
The doping variety of the rare earth is mainly Ce, and the amount of the addition
will be better controlled between 0.3 % and 0.8 % (wt). The performance of the Fe-
based diamond tool with the rare earth has basically reached that of the Co-based
diamond tool, offering the basis to realize the commercial production of diamond
tools based on the Fe matrix doped with a rare-earth element.
Emphasizing on the matrix formulation with 35 % (wt) Fe, the tests were car-
ried out on the service performance of rare-earth Fe-based diamond tool matrix and
a monolithic material (including coated or uncoated diamond). The tests have
shown that the bending strength and the impact toughness have been increased by
more than 10 % and 15 %, respectively, the porosity has been reduced by more
than 3 %, and the hardness has been improved only slightly.
In addition, the results indicate that the above four characteristics (the bending
strength, etc.) of the rare-earth Fe-based diamond tool matrix or a monolithic mate-
rial (including coated or uncoated diamond) are close to or exceed the correspond-
ing characteristics of the similar diamond tool composites without the Co base.
As to the diamond tools (bits and saw blades) manufactured by hot-press
sintering, trial drilling and productive cutting of granite have been carried out on an
indoor microdrilling test bench. The test results have indicated that the service life
of the coated diamond tools (the bit and the saw blade) and of those doped with the
rare earth has been improved on average by more than 20 % as compared with that
of the uncoated diamond tools free of the rare earth, the other technical and
economic characteristics have been greatly improved as well.
1. Zou Q. Ph. D. Thesis. — Wuhan, P. R. China: China University of Geosciences, 2000. —
P. 20—22 (in Chinese).
2. Zou Q. H., Zhao H. M., Zhang D. Y. et al. Thermophysics characteristics and densification of
powder metallurgy composite // Powder Metallurgy. — 2006. — 49, N 2. — P. 183—188.
3. Prokopiv M. M. Study of the microporosity of WC—Co alloys // J. Superhard Materials. —
2008. — 30, N 4. — P. 266—272.
School of Mechanical and Electronic Engineering Received 06.03.09
School of Science
Institute of Textile and Material
School of Computer Science and Engineering
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