Note: Descriptions are shown in the official language in which they were submitted.
~0~44~)~
The present invention relates to abrasive tools and
more particularly it relates to a bind for abrasive tools.
~ ~5
3 The present inventionAuseful in making abrasive tools t
on the basis of boron nitride or diamond. Such abrasive tools
are employed for rock drilling, in the building industry, for
cutting and grinding hard non-metallic materials. The abrasive
tools made of boron nitride with the bond according to the pre-
~na~ I nq
sent invention can be used for~ , for example, drill bits
for work in the rocks of VI-XI categories of drilling capacity,
drills for making holes in ferroconcrete, and cutorf wheels for
cutting stones.
With respect to the drilling capacity the categories
VI-XI of rock include albitophyres, aleurolites, a mphibolites,
apatites, gabbro, granites, gneissose-granites, gneisses, dunites, ;~ -
diorites, diabases, bauxites, basalts, beresites, iron ores,
metacherts and cornstone, ceratophires, conglomerates, quartz-
ites, labradorites, liparites, onokis, peridotites, sandstones,
pyroxenites, porphyries, pegmatites, corundum rocks, hornstones,
siderites, shales, syenites, skarns, diabasic and silicified
tuffs, trachytes, chromites, phosphorites.
A bond for abrasive tools is known based on natural
diamond comprising tungsten carbide, cobalt and copper as its
main components. This bond is a hard heat-resistant alloy with
a cermet structure and a sintering point above 1100C. However,
this bond cannot be used for abrasive tools based on boron
nitride because heat-resistance of the abrasive materal, e.g. -
cube boron nitride known in the USSR under the trademar~
"Elbor-R" does not exceed 1000-1050C. Heating such an abrasive `
material above 1050C cau~es a modified transition ~ BN -~ ~ BN
and the material loses its abrasive properties. Further, tung-
sten on which said bond is made is a rare, scarce and expensive
material, all this limiting the use of said bond.
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~54400
Also ~nown are metallic bonds for abrasive tools whose
sintering point is below 1000C. The hardest and most heat-resis-
cvonf~
tant of these bonds cont~o~ a metal of the iron sub-group of VIII
group in the periodic chart, copper and a low-melting metal, eOg.
tin. However, such bonds are unfit for use in the abrasive tools
intended for rock drilling since they lack the requisite hardness
and heat resistance which are inherent in the bonds with a cermet
structure.
Thus, the employment of abrasive tools, e.g. Elbor-R
drill bits with a bond based on tungsten carbide is impossible -
because the abrasive material is destroyed during manufacture
while drill bits made of ~lbor-R with a bond: metal or iron sub-
group -- copper-low-melting metal are unsuitable due to softening ~ ;
of the bond during operation of such drill bits.
The present invention provides a bond which is suffi-
ciently hard to be useful in abrasive tools based both on boron
nitride and diamonds and intended for drilling rocks of VI-XI
categories of drilling capacity (see the textbook "Technology
and Techniques of Exploration Drilling" hy F.A. Shamshev et al, -
Nedra Publishers, Moscow, 1966).
The present invention also provides a bond which
possesses a heat resistance near or equal to the thermal stability
limit of the abrasive tools based on boron nitride.
The present invention further provides a bond which
features good wettability with respect to the abrasive material,
i.e. boron nitride or diamond.
According to the prèsent invention there is provided a
bond for abrasive tools comprising 15 to 90 per cent by weight of ;
chromium carbide; 0.01 to 10 per cent by weight of at least one
of metals selected from the group titanium, vanadium, chromium,
zirconium, niobium, molybdenum and tungsten; l to 30 per cent of
a metal selected from the group tin, zinc, lead, aluminum, bismuth
-- 3
~054~0~
and cadmium; 2 to 30 per cent by weight of a metal belonging to
the iron subgroup of Group VIII of the Periodic table, and 3 to
75 per cent by weight of copper.
Thus in accordance with the present invention the bond
for abrasive tools comprises copper, a low-melting metal, a metal
of the iron subgroup of group VIII of periodic chart which, accor-
ding to the present invention, contains additionally chromium car
bide and at least one metal selected from the group titanium, vana-
dium, chromium, zirconium, niobium, molybdenum, tungsten.
Due to the inclusion into the bond of the chromium car-
bide, the hardness of the bind according to the invention is in-
creased to 70 Rc while its iheat resistance is raised to the ther-
mal stability limit of the used abrasive material -- boron nitride
or diamond; owing to the inclusion into the bond of transition
metals selected rrom IV - VI groups of the periodic chart, e.g. `~
titanium, the adhesion of the abrasive material to the bond is
raised to the strength limit of the abrasive material.
It is desirable that the bond for abrasive tools ~ ;
according to the present invention should contain 15 - 90 wt.-%
B 20 of chromium carbide, 2-30 wt.-% of metal from the iron subgroup
of VIII group of the periodic chart, 3 - 75 wt.-% of coppe~,
0.01 - 10 wt.-% of at least one metal selected from a group titan-
ium, vanadium, chromium, zirconium, niobium, molybdenum, tung-
sten, and 1 - 30 wt.-% of low-melting metal.
Besides, it is desirable that the bond according to the
invention should contain 73 wt.-% of copper, 20 wt.-% oE chro-
1~ . . .
rD~
- ~0544~
mium carbide, 1 wt.-% of titanium, 3 wt.-% of tin and lead
and 3 wt. -% of nickel.
Owing to the use of the bond according to the invention J
e.g. while making drill bits on the base of "Elbor-R"
material it has become possible to drill rocks of VIII-XI
categories of drilling capacity at a drill speed which is
1.5 - 2 times greater than those achieved formerly with the
drill bits made of diamond with a bond containing tungsten
carbide. While drilling rocks of VI - VIII categories of
drilling capacity the drill bits made of "Elbor-R" on the
bond according to the invention feature a drill speed which
is 1.5 and bit meterage 5 - 6 times greater, respectively,
than those of the drill bits of a hard alloy, i.e. bits made
by securing hard-alloy cutting elements in a steel body.
The operational characteristics of the drill bits of
natural diamonds with the bond according to the invention
approach those of the bits made of natural diamonds with a
tungsten carbide bond which makes it possible to substitute
the scarce and expensive tungsten carbide in the bonds for
drilling tools by a cheaper and easily obtainable chromium
carbide.
While drilling ferroconcrete the drills made of
"Elbore-R" with the bond according to the invention are 3 -4
times better than the diamond drilling tools with a bond
based on the tungsten carbide and than the carbide -faced
tools with respect to the drill speed.
Other objects and advantages of the present invention
will become apparent from the detailed description that follows
of the bonds for abrasive tools and from theexamples of said
bond
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The bond for abrasive tools according to the present
invention includes copper, a low-melting metal, e.g. tin,
a metal from the iron subgroup of VIII group of the periodic
chart. It is known that the bond which includes only these -
components is a low-temperature material and has a metallic
structure. We have found that a low` temperature bond with
a cermet structure can be produced by merely introducing ~`
chromium carbide. We have chosen chromium carbide due to
the following considerations: it possesses good wettability
with respect to the metals of the iron subgroup of VIII
group of the periodic system and to copper; it has a high
hardness (microhardness about 14000 kg/mm ); besides, chro-
mium carbide is cheaper and its production on an industrial
scale involves no complications that are characteristics oftungsten carbide production.
We have investigated a number of mechanical properties
of alloys in the system of chromium carbide - nickel - copper
tin, such as hardness, bending strength, modulus of elasti~
city, impact strength and sintering point, using a hot-
pressing method under a pressure of 0 - 300 kg/cm . We
have established that, depending on the composition of the ~:
alloys, the hot pressing temperature varies from 750 to
lZ00 C with a simultaneous change in hardness from 80 RB
to 70 Rc, i.e. this covers the entire range of hardnesses of
the bonds for drilling tools. It should be noted that the
hot-pressing temperature is the temperature at which the
alloy reaches the rated maximum density at a given unit
pressure.
- 6 -
~ . .
~544C~
A consideration of the phase composition of the
alloys has shown that at a temperature of 750 - 1200C
the metallic part of the alloy becomes comparatively homo-
genized (the metallic
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- 6a ~
~0~4g(~ `
part of the alloy includes copper a metal from the iron
subgroup - a low-melting metal) with a simultaneous partial
re-crystallization of chromium carbide through the liquid
metallic part of the alloy which leads to the formation of
a bond with a cermet structure. .
It has been found that the greatest adhesion to the
materials based on boron nitride is displayed by strong
transition metals included into IV-VI groups of the periodic ;
chart, namely, titanium, vanadium, chromium, zirconium, nio-
bium, molybdenum, tungsten. The contact of the above-men~
tioned metals or alloys containing said metals with boron -
nitride produces a reaction: BN + Me- ~ MedBb + MecNd ..
i.e. there takes place the surface decomposition of boron ~.-
nitride and formation of new phases, i.e. borides and
nitrides of the above-men-tioned transition metals. Depend-
ing onthe relation between the thermal effect produced by -
the formation of nitrides and borides of the corresponding
metal it may occur either that the borides and nitrides
of the metal will be formed simultaneously or that formation
of the borides will be accompanied by liberation of nitrogen `
in the form of gas or there will be predominant formation
of nitrides. -:
In any case new phases will be formed on the surface
of contact between boron nitride and the transition metal or
the alloy containing this metal which ensures wetting of
boron nitride. Therefore, we deem it practicable to intro-
_ 7 -
~C~5440~
duce into the bond according to the invention at least one
metal ~elected from the group includ ng titanium, vanadium, :~
chromium, zirconium, niobium, molybdenum, tungsten.
.~.., ~ .-.
- 7a -
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.-
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44~
While investigating the contact layer at the boundary:
abrasive material - bond according to the invention in the
form of an alloy consisting of copper - metal from the iron
subgroup of VIII group of periodic chart - low-melting metal
said transition metal belonging to IV - VI groups of the
periodic chart we have established the presence of new
phases (borides and/or nitrides of the used transition metal)
i.e., we have proved wettability of the abrasive material
by the bond. The strength of adhesion of the abrasive mater- `
ial to the bond has increased, becoming commensurate with `
the strength of the abrasive material itself.
The bond consisting of copper - metal of the iron sub_
group of VIII group of the periodic chart (cobaltj iron, -
nickel) - a low-melting metal (tin, zinc, lead, aluminium,
bismuth,cadmium) -s taken as a source metallic bond for
transformation into a low-temperature cermet bond on the
ground of the following considerations.
1. Copper constitutes the base of practically all-
low-melting alloys (melting temperature below 1000 C) with
comparatively high mechanical properties since alloys based
on noble metals are scarce and expensive; the alloys based
on low-melting metals such as, say, aluminium orzinc have
very low mechanical properties, the bonds based on the metals ~-`
of the iron subgroup or on such metals as molybdenum or tung-
sten have a too high melting temperature while the bonds ;
based on titanium are too high melting and difficult to pro-
cess.
Thus, the alloys based on copper are sufficiently strong,
- 8 -
~)S440~
heat-conducting and can easily be processed; besides, copper
alloys dissolve the above-mentioned transition metals such
as titanium, zirconium, niobium.
2. The metals of the iron subgroup of VIII group o~
the periodic chart are easily; fused with copper, i.e. the
base of the alloy (e.g. nickel with copper forms continuous
solid solutions) and increase the heat resistance of copper
alloys. In addition, the metals belonging to the iron sub~
group of VII group of the periodic chart wet efficiently the
chromium carbide
(the angle of wetting of chromium carbide)with these metals
is near or equal to zero), which is an indispensable prere- ,!
quisite for forming cermet, and dissolve chromium, vanadium,
titanium, zirconium, niobium, molybdenum and tungsten.
3. Low-melting metals are required for reducing the ;
melting temperature of the alloys consisting of copper and
said metal of the iron subgroup, all of which have a melting ~`
temperature higher than that of copper (1083 C). Besides,
it is known that introduction of tin into copper-nickel
alloys improves their strength and hardness.
The bond according to the present invention includes
the following components:
chromium carbide 15 - 90 wt. -~0.
metal of iron subgroup of
VIII group of perio-
dic chart 2 - 30 wt.-%,
copper 3 - 7~ wt.-~o;
low-melting metal 1 - 30 wtJ-~;
at least one metal selected from the group including
titanium, vanadium, chromium, zirconium,
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lOS~
niobium, molybdenum,
tungsten 0.01 - 10 wt.-%.
The above proportion of the components in the bond
according to the invention is motiva-ted by the following con-
siderations.
The alloys containing less than 15 w-t. -~ of chromium
carbide do not differ in mechanical properties from purely
metal alloys in spite of the change to the cermet structure.
We have found that the alloys containing more than 90 wt.
-% of chromium carbide have a too high sintering temperature
(above llOO C); besides, such alloys are difficuly to process
since they are sintered with a high residual porosity.
Copper and chromium carbide being the basic components
of the bond according to the present invention, an increase
in the proportion of one of them brings about a corresponding
decrease in the content of the other. An increased propor-
tion of copper ,reduces the sintering temperature, hardness
and heat resistance of the bond; an increased proportion of
chromium carbide produces a contrary effect. Therefore,
when the copper content is below 3 wt.-%, the alloys prove
to be excessively high melting, while the proportion of
copper exceeding 75 wt. -~ causes the content of chromium
carbide to drop below the practicable value.
According to the present invention, the bond for abra-
sive materials contains not over 30 wt. -% of metal belonging
to the iron subgeoup of VIII group of the periodic chart
otherwise
.... .
1 0
~054~
the alloy becomes too high melting while the proportion of
said metal of the iron subgroup below 2 wt.-% exerts prac-
tically no influence on the properties of the alloy which
fact has just caused the suggested lower limit of constant
of, say, nickel in the bond for abrasive tools.
Experiments have shown that introduction into the bond
aCcording to the invention of such low-melting metal as tin
in a proportion less than 1 wt. -% fails to exert such an
effect on the properties of the bond which is expected after
the introduction of a low-melting metal; if the prop~ortion
of the low-melting metal is increased above 30 wt.-% there
appears an excessively brittle phase in the metal part of
cermet which weakens the cermet. -
It must be noted that the quantity of introduced metal
depends practically on its nature.
For example, it is impracticable to introduce tin in
a quantity more than 18 - 20% of the copper content, i.e.
more than 15 w-t.-% it is possible to introduce up to 30 wt.-%
of zinc wh~ch corresponds to 40% of copper content. `
The content of the metal selected from the group which
includes titanium, vanadium, chromium, zirconium, niobium,
molybdenum, tungsten in the bond according to the invention
has been determined considering the nature of the used metal
and said content may vary widely.
Thus, practically it is possible to obtain the effect
of wettability by introducing as little as 0.01 wt.-% of
such elements as chromium or titanium while the content of
such elements
- 1 1 - t
~1)5~4~
as molybdenum, vanadium or tungsten may reach 5 - lO wt.
%
. .
The qualitative and quantitative composition of the
bond can be checked by a combination of spectral, X-ray
diffraction and microscopic analyses.
Example 1. Drill bits of 59 mm diameter with the
volumetric and cut-ting elements made from cube boron -
nitride blanks 4 mm in diameter and 4 mm high employ the
bond of the following composition: chromium carbide 23.6 g,
nickel 4.30 g, copper 99.8 g, tin 4.8 g, lead 0.3 g, titan-
ium 0.2 g.
The bits are hot-pressed at a pressure of 150 kg/cm and
a temperature of 950C.
The bits made by this method are used for drilling
iron quartzite of X-XI categories of drilling capacity with ;
wash water. The drill speed averaged 2.5 m/hr at an aver- ,
age bit meterage of 1 m. The diamond drill bits with the
bond based on tungsten carbide have produced an average
mechanical drill speed of 0.8 m/hr at an average bit
meterage of 0.8 linear metres.
Example 2. Drill bits of 59 mm dia with the volumetric
and cutting elements made from cube boron nitride blanks 4
mm in diameter and 4 mm high employ the bond of the following ~'
:,
composition: -
chromium carbide 78 g ~
nickel 11.7 g, -~ -
copper 26.1 g -~
tin 8 g -
cadmium 2 g
vanadium 4.5 g
- 12 -
... . .,. ,. - - . , . , :.
~0~40~
The bits are hot-pressed at a pressure of 300 kg/cm
and a temperature of 1000C.
The bits manufactured in this manner are used for
airblast drilling of monolithic quartz reefs~:of X category
of drilling capacity. The average mechanical drill speed
is 4.6 m/hr and the bit meterage 0.80 linear metre.
Under the same conditions the diamond drill bits with
a bond based on tungsten carbide display a drill speed of
1.35 m/hr at a bit meterage of 0.8 m.
Example 3. Drill bits of 59 mm diameter with the
volumetric and cutting elements made from cube boron nitride
blanks 4 mm in diameter and 4 mm high employ the bond of the
following composition:
chromium carbide 20.4 g
Nickel 3~4 g
copper 67.5 g
zinc 36.3 g ;~
aluminium 0.8 g
chromium 0.05 g
The bits are hot prOessed at a pressure of 150 kg/cm
and a temperature of 780 C. The bits produced in this ;
manner are used for dilling iron quartzite of X - XI categor-
ies of drilling capacity with wash water. The average `~
mechanical drill speed is 2.3 m/hr at a bit meterage of 0.9
linear metre; the average mechanical drill speed of the dia-
mond bits with a bond based on tungsten carbide while drilling
the same rocks is 0.8 m/hr at an average bit meterage of 0.8
linear metre.
~ r
- 13 -
~054~0~
~ _an~le 4. Drill bits of 76 mm diameter with the
volumetric and cutting elements made from cube boron ni-tride
blanks 4 mm in diameter, 4 mm high employ the bond of the
following composition:
chromium carbide107.3 g
nickel 9.4 g
cobalt 4.8 g
copper 60.5 g
tin 11.8 g i`
bismuth 0.3 g
zirconium 0.3 g
The bits are hot-pressed at a pressure of 150 kg/cm2
and a temperature of 1000C. `
The bits manufactured in this manner used for drilling
argillite-siltstone stratum with sandstone streaks of VII cate~
gory of drilling capacity have an average mechanical drill speed
of 8 m/hr at a bit meterage of 80 linear metres. While drilling
the same rocks, carbide-faced bits ensure a drill speed of 5.5
m/hr at a bit meterage of 14 linear metres.
Example 5. Drills of 36 mm diameter with the cutting
elements made of cube boron nitride blanks 4 mm in diameter, 4
mm high employ the bond of the following composition:
chromium carbide5.8 g
iron 3.1 g
copper 17.8 g
tin l.9 g
niobium 0 3 g
titanium 0.1 g
- 14
.
- ' 3LOS~
~ he drill~ are hot pxessed at a pressuxe ~f 150 k~/cm2 a~d
a temperature ef 1000C.
Whil2 d:rilli~; f èrroconcrete lwith a s~rength o~ 300 kg/cm2
and rainforceme~t bars of 12 - 16 mm diameter the average drill
speed is 4 - 5 m~hr at a drill meterag~ OI 31~5 linear metr~s.
Under the sam8 conditions diamond drills l-ith a bond base
on tungsten carb~de en~ure a mechanical dr~ll speed of 1.3 mJhr
at a drill meterage o~ 1.5 linear ~etres; under the ~ama co~-
ditions carbide-îaced drills give a mechAnical speed of 105
m/hr at a drill meterage of 0.7 linear metre.
E~am~le 6. Dr~ll bit~3 oî 59 mm di~meter made o~ natural
diamond employ the bond of the followiD~ compo~ition:
chromium c&rbid0 55.6 g
~ickel 44 g
copper 35.3 g
tin 1.6 g
moly~denum 8.7 g
chlomium 201 g
tungsten 2.5 g
~ he bit~ are hot-pres~ed at a pressure o~ 150 kg/em2 a~d a
temperature o~ 1250C.
During ai~bla~t drilling o~ monolithic quartz o~ X category
of drill~ng capacity the average drilliDg spcad i~ 1.5 mJhr at
a bit meterage of 0.9 m.
Undsr the same condition~, similar diamo~d bits with a bo~d r
based on tungsts~ carbide give a drill speed o~ ~.35 m/hr at a
bit meterage o~ 0.8 linear metre.
_ 15 _
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~ OS ~40 ~
Example ~. Drill bits of 59 mm diameter made rrom ~atural
diamond emplo~ the bond of the ~ollowi~g cemposition:
chromium carbide 109.2
cobalt 1.3 ~
nickel 10.9 g
copper 6.5 g
tin 1.4
titanium 0.2
~ he bits are hot-pressed at ~ pres~ure o~ ~00 ~g/cmZ and
temperature of 1000C.
While drilling red granite ~lab~ of VIII-IX ca~eg~rie~
o~ drill~ng capacity the a~erage mechan~cal drill speed i~
3.0 m/hr at a bit meterage o~ 32 linear metres.
Under the ~ame conditions the ~iamond bit~ ~ith the bond
basQd o~ tungs~en carbide give a drill speed of 2.2 mJhr at a -`;
bit meterage of 34 linear ~e~res.
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