Note: Descriptions are shown in the official language in which they were submitted.
lOS8841
~ he present invention relates to p~oducing rsfractory in-
organic materials, a~d more speci~ically to a method of obtain-
ing cast refractory inorganic materials, including æuch compo-
unds as carbides, borides, silicides, and nitrides of metals
selected ~rom the IV, V and VI groups of the periodic system,
as well as hard alloys and hard alloys with alloying additi-
ves. ~hese materials ~eature high hardness, strength, wear
resistance and ~ind extensive application in the manufacture
of cutting tools, chemical~, refractories, abrasives and ma-
chine tools.
~ here is known a method o~ obtaining cast refractorg
inorganic material~ by way o~ hèating the powder of inor-
ganic compounds in electric orens or electric arc under at-
mospheric pressure to a melting point as high as 2,000 to
4,000E.
~ his method is disadvantageous in that it is impossible
to obtain cast rsfractory inorganic materials, such as borides,
silicides, and carbides o~ tungsten, chromium, molybdenum pos-
~essing properties meeting industrial requirements because o~
their partial decomposition at the melting point. ~his leads
to ~ormation of a ~ree metal and a non-metal, which results in
lower melting point and hardness o~ the material~ as well as
results in ~ormation o~ pores and cavities.
Other disadvantages of the prior art method are the pos-
sibility of producing onlg small castings, the necessity to
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1058841
obtain, first~ a powder o~ the refractory inorganic compound,
the use of sophisticated equipment, low capacity of this equip-
ment, and high electric power co~sumption.
Industrial hard alloys are also produced by sintering pow-
ders o~ a refractory inorganic compound and a binder metal at
elevated temperatures and under high pressures.
Disadvantages inherent i~ this method are the poQsibility
of obtaining only small si~tered specimen~, their porosity and
presence of free carbon therein, which affects their strength,
the use o~ sop-histicated equipment, low capacity of this e~uip-
ment and high consumption o~ electric power.
~ here is known still another method o~ obtaining starting
powders of refractory inorganic compounds for producing cast
materials, by igniting a small portion of the sur~ace layer o~
the metal-non-mctal mixture, i.e. heating it to a temper~ture
suf~icient for initiating the process of combustion in a thin
layer of the starting components, in which case the propaga-
tion of the combustio~ zone ~rom one layer to another is due
to the heat reIeased as a result of the reaction between the
starting co~ponents and heat transfer. ~hus, the reaction pro-
ceeds in a thin layer of the mixture, which is known as the
combu~tion zone, where temperature is as higrh as 2,000 to
4.000E. The combustion zone propàgates in the mixture at a
rate of 1 to 15 cm/sec. The process is conducted in an air-
tight vessel, in an inert gas medium.
los884~
It is an object of the present invention to pro~ide a
method of obtaining cast re~ractory inorganic materials with
chemical composition, hardness, mechanical properties and po-
rosity such as to meet industrial re~uirement3.
Another object of the invention is to provide a method of
obtaining cast refractory inorganic materials, such as will
permit producing castings of any size and shape.
Still another object of the invention is to provide a me-
thod o~ obtaining cast refractory inorganic materials, such as
will permit producing castings in the process of synthetizing
refractory materials, which eliminates the step of preparing,
in advance, powder~ of refracto~y inorganic compounds.
With these and other objects in view, the present inve~-
tion is aimed at providing a method of obtaining cast refrac-
tory inorganic materials, wherein, according to the invention,
at least one oxide of a metal selected from the IV, V and VI
groups o~ the periodic system is mixed with a metallic reducer
and a ~on-metal or an oxide thereo~, whereafter a small portion
of the mi~ture surface is ignited in a gaseous medium, which
results in propagation of the mixture combustion zone with the
mixture burning under a pressure of 1 to 5.000 atm, to obtain
the end product.
~ o obtain cast hard alloys based on refractory inorganic
compounds, introduced into the mixture should pre~erably be
nickel, cobàlt, molybdenum or oxides thereof in an amount o~
~rom 5 to 20 wt %.
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~o5884~
To improve the mechanical properties of hard alloys,
it is expedient to introduce into the mixture such alloying
additives as manganese or magnesium in an amount o~ from 1 to
5 wt %.
To prevent the volatile components of the mixture from
evaporating ~rom the mixture and dissociation of the end pro-
duct, synthesis should pre~erably be conducted under a pressure
o~ 00 to 5,000 atm.
~ o prevent porositg and cavities in the end product,
synthesis should preferably be conducted in steady rotation
conditions at centrifugal accelerations of 100 to 1,500 g,
wherein g is the ~ree fall accele~ation~ and in a gaseous me-
dium under a pressure of 1 to 100 atm.
~ o obtain cast re~ractory inorganic materials the synthe-
~is temperature whereof i~ below their melting point, the mix-
ture should preferably be heated prior to ignition to a tempe-
rature equal to the difference between the melting point .
of the end product and the normal synthesis temperature.
The herein proposed method of obtaining cast refractory
inorganic materials is realized as follows.
Introduced into a reaction mixture including oxides of me-
tals selected ~rom the IV, V and VI groups of the periodic
system, a metallic reducer, such as aluminum or magnesium, is
a non-metal or an oxide thereo~, for example~ carbon~ boron,
boron oxide, silicon, silicon oxide, nitrogen; then, a small
~o58~4~
portion of the mixture sur~ace is ignited in a gaseous medium
under a pressure o~ 1 to 5,000 atm. In obtaining nitride~,
u~ed as the ~aseous medium is ~itrogen, while in the other ca-
ses use is made of an inert medium, such as argon.
Pressure is required in the process of synthesis to pre-
clude violent escape and explosion o$ the reaction mixture.
I~ addition, to prevent evaporation of the volatile components
a~d dissociation of the refracto~y inorganic components, synt-
hesis is conducted under a pres~ure of 1,000 to 5,000 atm. The
max~ mum pressure is limited by the strength o~ the reactor in
which synthesis takes place.
~ ynthesis is based on utilizing the heat of the chemical
reaction of interactio~ of the reaction mixture components and
takes the $orm of combustion. The mixture is ignited by a
heated tungsten coil or any other conventional means locally
in the æurface layer. Combustion proceeds as $ollowss the sur-
face layer of the mixture is ignited and reacts evolving a
great amount of heat which is partially trans$erred to the
adjacent cold layer; the latter is heated, in turn, ignited,
enters into reaction, part of itæ heat being transferred to
the next adjacent layer by way of heat conduction.
Formed in the course of synthesi~ are the end product and
slag, i.e. oxide o$ the metallic reducer, which are liquid at
the syntheæis temperature and separated because of difference
in their specific gravities~ At the end o$ the process, they
æolidi~y $orming distinct layers and can easily be separated
$rom each other.
- 6 -
.
~oss84~
~ he sizes and shapes of the resulting cast refractory
inorganic materials are determined by those of the reactor,
which may be various.
In order to obtain hard alloys, introduced into the reac-
tion mixture in addition to the above-mentioned components is
a binder metal, for example, nickel, cobalt, molybdenum or
their oxides in an amount of from 5 to 20 wt %~ Introduction
of a lesser amount of the binder metal does not ensure the
required plasticity of hard alloys, while an excess of the
binder metal substantially reduces their hardness.
~ o prevent porosity and cavitie as well as to accelerate
separation of the end product from slag, synthesis is conduct-
ed with a centrifugal acceleration of 100 to 1,500 g (g being
the free ~all acceleration) in steady rotation conditions.
Centrifugal acceleration is created by a centrifuge. The
centrifuge is a thick-walled reactor in which synthesis is
conducted and which rotates about its axis.
~ he centrifuge provides for a gaseous medium pressure
from 1 to 100 atm and centrifugal acceleration from 100 to
1,500 g-
~ o impart to hard alloys the required mechanical proper-
ties, ~or example, impact resilience or bending strength, in-
troduced into the reaction mixture is an alloying additive,
such aæ manganese or magnesium, in an amount of from 1 to
5 wt %.
-- 7 --
1058841
Introducing more than 5 wt % o~ the additive is not
recommended for this may result in lower hardness and melting
point of the allogs.
When it is necessary to obtain ca~t refractory inorganic
materials the synthesis temperature whereo~ is less than their
melting point, for example, carbides of tungsten, zirconium,
hafnium, or tantalum, the starting mixture i~ heated, prior to
ignition.
~ he temperature of heating the starting mixture must be
su~ficient for the inorganic refracto~y material to melt in
the process o~ synthesis noDmally the heatin~ temperature ~or
different mixtures is selected e~perimentally. In the case of
mixtures, whose synthesis temperature is known, the starting
mi~ture heating temperature is equal to the difference between
the melting point of the refractory compound and temperature
of its synthe is under normal conditions. In the case o~ tungs-
ten carbide, for example, the mixture is heated to a tempera-
ture o~ 300 to 550C-
The proposed method permits obtaining cast refractory in-
organic materials of any size and shape with properties ~atis-
fying industrial requirements. Obtaining a cast material by
this method enables dispensing with sophisticated equipment
including presses and ovenæ a~ well as some of the steps nor-
mally indispensable when such materials are produced b~ sinter-
ing u~der industrial conditions, namely:
-- 8 --
105884~
1) the step of producing metal from its oxide and non-
-metal from its o~ide~
¦ 2) the step o~ synthetizing the starting refractory com-
pound.
The method of this invention will be better understood
from the following example~ illustrating the manner in which
it can be realized.
Exam~le 1 Obtaining ¢ast Mo2C.
288 g of MoO3~ 12 g of carbon and 108 g o~ Al were mixed
in a mixer for one hour. The re~ulting mixture was charged
into a reiractory cylindrical container and pac~ed therein~
bhen, the container with the mixture was placed in a reactor.
The mixture was ignited by mean~ of a heated tungsten coil,
the pressure of the gas in the reactor being equal to 1 atm.
Combustion was accompanied by violent escape of the mixture.
After combustion, the sample was allowed to stay in the
reactor for one hour during which period the end product
(Mo2C) wa~ completely separated from slag (Al203), both compo-
nents be mg liquid at the s~nthesis temperature; then, both
components solidified in two distinct layers and were cooled
down to room temperature.
.
End Product _haracteristics
Obtained as a result of synthesis was a cast cylindrical
piece divided into two layers. The top layer was grey and brittl
~ _ g _
1058841
le (A1203), while the bottom layer was ~ilvery and hard
(Mo2C). ~he yield was 20 wt % o~ the expected value because
o~ the mi~ture escaping violently from the container, resulting
in tin~ pores and cavities in the end product.
X-Ra~ Phase Ana~is_Data
The end product wa~ a mixture of Mo2C and Mo.
Qhemical_~nalysis Data_
Content of ~ixed carbon~ in wt ~: 5.85 - calculated for
Mo2C~ 4.2 -Iound.
.,
Microhardness _nd De_s_t~ Ana~ysis_Data
Microhardness, in kg/mm2s 1,500 to 1,800 - according to
literature~ 1,790 - found.
De~ity, in g/cm3: 9.2 - according to literature; 9.1
found.
Exam~le 2 Obtaining ca~t Mo2C.
288 g of MoO3, 12 g o~ carbon and 108 g of Al were mi~ed
in a mixer for one hour. ~he resulting mixture was charged
into a refractory cylindrical container ~nd packed therein.
~he container with the mixture was then placed in a reactor.
~he mixture was ignited by a heated tungsten coil, the pres-
sure of argo~ in the reactor bei~g 100 atm.
- 10 _
105884'1
During combustion, no Yiolent escape of the mixture was
observed. After combustion, the sample was removed from the
container.
End Product Ch3racteristics
The synthesis product was a cast cylindrical piece di-
vided into two distinct layers. The top laye~ was grey and
brittle (A1203), while the bottom layer was silve~y and hard
(Mo2C). ~he yield of Mo2C was 100 wt % of the expected value.
The end product is ~ree o~ pores and cavities.
Chemical Ana~y~is Data
Cont~nt of fixed carbo~, in wt %: 5.85 - calculated for
Mo2C; 5.6 - ~ou~d.
X-Ra~ Phase Anal~s~s_Data
~ he end product was Mo2C.
1 ,
Microhardness and Den~it~ Ana~is Data
Microhardness, in ~g~mm2: 1,500 to 1,800 - according to
literature~ 1,790 - found.
Density, in ~/cm3: 9.2 - ac¢ording to literature; 8.8 -
- found.
ExamPle 3 Obtaining cast Mo2C.
288 g o~ ~oO3, 12 g o~ carbon and 108 g of Al were mixed
in a mixer for one hour. The re~ulti~g mixture wa~ charged into
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lOS8841
a re~ractory cylindrical container and packed therein. The
container with the mixture was then placed in a reactor. ~he
mixture was ignited by a heated tungsten coil, the pressure
of argon in the reactor being equal to 2,000 atm. Combustion
proceeded without violent escape of the mixture. After combus-
tion, the sample was removed from the container.
End Product Characteristics
The synthesis product was a cast cylindrical piece divided
into two distinct layers, the top layer being grey and brittle
(A1203) and the bottom layer being silvery and hard (Mo2C). ~he
yield of Mo2C was 100 wt % o~ the expected value. ~o pores and
cavities were found.
Ch_mic_l_Ana~ysis Data
Content of fixed carbon, in wt %: 5.85 - calculated ~or
Mo2C~ 5.8 - found.
g-Ra~ Phase A~al~sis_Data
The end product was Mo2C.
Microhardness 3nd Densit~ Ana~y is Data
Microhardness, in kg/mm2: 1,500 to 1,800 - according to
literature; 1,790 - found.
Density, in g/cm3s 9.2 - according to literature; 8.8 -
~ound.
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105884~
~xam~le 4 Obtaining cast Mo2C
288 g o~ ~oO3, 12 g of carbon and 108 g o~ Al were mixed
in a mixer for one hour. The resulting mixture was charged in-
to a refractory cylindrical container and packed therein. The
container with the mixturs was then placed on a centrifuge
which was rotated. The centrifugal acceleration was brought
up to 1,000 g, wherea~ter the mixture was i~nited with a heated
tungsten coil, the pressure in the reactor being 1 atm. Comb~ -
tion proceeded without violent escape of the mixture. After
combustio~, the sample was withdrawn from the container.
~nd Product Characteristics
_ _ _ _ _ _ _ _ _ _ _ _ _ _
The synthe~is product was a cast cylindrical piece divid-
ed into two distinct layers. The top layer wa~ gre~ and brittle
(A1203), while the bottom layer was silvery and hard (~o2C).
The yield of ~o2C was 100 wt % o~ the expected value. The end
product was free of pores and cavities.
X-Ra~ Phase Anal~s_s_Data
~ he end product was a mixture o~ Mo2C and Mo.
Ch_mical_Ana~ysis Data_
Content of fixed carbon, in wt %: 5.85 - calculated for
Mo2Ct 4.4 - found.
- 13 -
- 1058841
Microhardness Anal sis_Data
Microhardness, in kg/mm2: 1,500 to 1,800 - accordin~ to
literature~ 1,790 - found.
Examples 5-8 Obtai~ing cast Mo2~.
The process was conducted as in ~xample 4. The pressure
of argon was 100 atm and centri~ugal accelerations were 100,
300, 1,00 and 1,500 g, respectively. For end product charac-
teristics ~ee Table.
Example 9 Obtaining cast VC.
The process was conducted as in Example 1. For end pro-
duct characteristics see Table.
Exam~le, 10 Obtaining cast ~C.
The proces3 was condu¢ted as in ~xample 2. ~or end pro-
duct characteristics see Table.
ExamPle 11 Obtaining cast VC.
The process was conducted as in Example 3. For end pro-
duct characteristics see Table.
Example ?2 Obtaining cast VC.
The process was conducted a~ in Example 4. ~or end pro-
duct characteristics see Table.
Examples 13, and 14 Obtaining cast VC.
The process was conducted as in Example 4, the preqsure
being equal to 100 atm a~d centrifugal accelerations being
100 and 1,500 g, respectivel~. For end product characteristic~
see ~able.
- ~4 -
1058841
Exam~le 15 Obtaining cast Cr3C2.
The process was conducted as in Example 1. For end pro-
duct characteristics see '~able.
ExamPle 16 Obtaining cast Cr3C2.
~ he process was conducted as in Exa~ple 2. For end pro-
du¢t characteristics see ~able.
i E~am~le 17 Obtaining cast Cr C .
3 2
The process was conducted as in Example 3. Eor end pro-
duct characteristics see ~ablé.
ExamPle 18 Obtaining cast Cr3C2.
The process was conducted as in Example 4. ~or end pro-
duat characteristics see ~able.
~ xamples 19 and 20 Obtaining cast Cr3C2.
~ he process was conducted as in ~xample 4 under a presqure
o~ 100 atm and at a centrifugal acceleration of 100 and 1,500g,
respectively. For end product characteristics see Table.
ExamPle 21 Obtai~ing cast ~C.
232 g o~ W03, 12 g o~ carbon and 54 g o~ Al were mixed in
a mixer for one hour. The reæulting mixture was charged into
a refractory container, conical in shape, and packed therein.
Then, the container with the mixture was placed in a reactor
and heated to a temperature o~ 300C. The mix*ure was ignited
b~ a heated tungsten coil, the pressure in the reactor being
equal to 5 atm. The temperature in the combustion zone was
2~600 to 2,700C under normal conditions, the melting point
o~ WC being equal to 2,870C. For e~d product characteristics
see ~able.
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1058841
Examples 22 and 23 Obtaining cast WC.
The process was conducted a~ in Example 21, the starting
mixture being heated to 550C under an argon pressure of 100
and 2,000 atm, respectively. ~or end product characteristics
see ~able.
ExamPles 24-32 Obtaining cast Mo~.
For process parameters and end product characteristics
see ~able.
xample 32 Obtaining cast VN.
552 g of V205 and 270 g of Al were mixed in a mixer for
one hour. The resulting ~ixture was charged into a re~ractory
cylindrical container and pac~ed therein. The mixture was ig-
nited by means o~ a heated tungsten coil, the nitrogen pressu-
re i~ the reactor being 100 atm. Combustion proceeded without
violent escape of the mixture. After combustion, the sample
was extracted from the container.
, .
End Product _haracteristics
he synthesis product was a cast piece divided into two
distinct layers: the top layer was grey and brittle (Al203),
while the bottom layer was grey brown and hard (V~). The
yield o~ VN was 100 wt % of the expected ~alue. The end pro-
duct had pores and cavities.
- 16 -
1058841
X-Ra~ Phase Anal~sis Data
~he end product was a mixture o~ VN, V3~, and V.
.
Chemical Ana~sis Data
~.~",,
Content o~ ~ixed nitrogen, in wt %: 21.6 - calculated
for VN~ 11.5 - found.
ExamPle 33 Obtaining cast VN.
~ he process wa~ conducted as in Example 32. ~or end pro-
duct characteri~tics see Table.
Ex~mPle 34 Obtaining a hard alloy containing 30 wt ~ of
TiC, 60 wt % of Mo2C, 10 wt % oP Ni.
87 g of MoO3, 40 g of ~iO2, 10.5 g of NiO, 11 g of
carbon~ and 36 g of Al were mixed ~or one hour, the resulting
mixture being char~ed into a re~ractory cylindrical container
and packed therein. ~he container with the ~ixture was then
placed in a reactor. The mixture was ignited by a heated
tungsten coil, the reactor pressure being 1 atm. Combustion
was accompanied by violent escape of the mixture. A~ter com-
bustion, the sample was removed from the container.
- ~nd Product Characteristics
-- _ _ _ _ _
The product was a cast cylindrical piece dirided into two
layers. ~he top layer was greay and brittle (Al203), while the
bottom la~er was silvery and hard (hard alloy). ~he yield o~
the end product was 30 wt % of the expected value.
- 17 -
: 1058~41
,, .
~-Ra~ Phase _nal~si~Data
' ~he end product was a mixture of ~iC, Mo2C, C~ ~i, and
Mo.
,~ Ch_mical_Analysis Data
s Content of ~ixed carbon, in wt %: 7.5 - calculated for
~ l 30 wt % of TiC, 60 wt ~ of Mo2C, 10 wt % of Ni; 7.0 - found.
,. . .
Dens_t~ Anal~sis_Data
Density, in g/cm3: 8.2 - obtained.
Examples 35-39 Obtaining a cast hard alloy containing
95 wt % of TiC, 60 wt % o~ Mo2C, 10 wt %
of ~i.
For end product characteristics see Table.
Examples 40-42 Obtaining a cast hard alloy containin~
95 wt % of WC, 5 wt % of Co.
~or end product characteristi~s see ~able .
ExamPles 43-45 Obtaining a cast hard alloy containing
90 wt % of WC, 10 wt % of Co.
~or end product characteristics see ~able.
Exam~les 46-48 Obtaining a cast hard alloy containing
80 wt % of WC, 20 wt % of Co.
~or end product charactexistics see Table.
~am~les 49-51 Obtaining a cast hard alloy containing
50 wt ~0 o~ ~iC, 40 wt % of Cr3C2, 10 wt
% of Ni.
~or e~d product charac~eristics see ~able.
- 18 -
,
10 5 8 8 41
_xamDles 52-54 Obtaining a cast hard alloy containing
90 wt % of VC, 10 wt % of Co.
~or end product characteristics see ~able.
Exam-ples 55-57 Obtaining a cast hard alloy containing
: .
90 wt % o~ MoB, 10 wt % o~ Ni.
For end product characteristics see ~able.
Examples 58-60 Obtaining a cast hard alloy with alloy-
ing additi~es, containing 85 wt % of VC,
10 wt % of Ni, 5 wt % of Mn.
~or end product characteristics see ~able.
~xamles 61-63 Obtaining a cast hard alloy with allo~ing
additives, containing 85 wt % o~ VC,
14 wt % of Ni, 1 wt % of Mn.
For end product characteristics see Table.
Examples 64-66 Obtalnin~ a cast hard alloy with alloyin~
. .
additives, containing 45 wt % of ~iC,
40 wt % o~ Cr3C2, 10 wt ~ o~ ~i, 5 wt %
o~ Mn.
~or end product characteristics see ~able.
~xamPle 67 Obtaining a cast hard alloy with alloying
additives, containing 45 wt % o~ ~iC, 44 wt%
of Cr3C2, 10 wt % of Ni, 1 wt % o~ Mg.
For end product characteristics see ~able.
Examles 68-71 Obtaining cast W2~.
For end product characteristics see ~able.
- 19 -
1058841
xamples 72-?4 Obtaining a cast hard alloy containing
90 wt ~ of WC, 10 wt % o~ Mn.or end product characteristics see ~able.xamples 75-77 Obtaining a cast hard alloy containing
85 wt % of Cr3C2, 15 wt % of Mn.
~or end product characteristics see l'able.
xamPle~ 78-BO Obtainin~ cast NbSi2.
~or end product characteristic~ see Ilable.
Examples 81-83 Obtainin~ cast V3Si.
~or end product characteristics see Table.
xamples 84-86 Obtainin~ cast WSi2.
For end product characteristics ~ee ~able.
ExamPle 87 Obtaining cast MoSi2.
For end product characteristics see ~able.
xamples 88 and 89 Obtaining a cast complex carbide
containning 30 wt % of TiC, 70 wt %
o~ Mo2C.
~or end product characteristics see Table.xamPles 90 and 91 Obtaining a cast complex silicide
containing 50 wt % of MoSi2, 50 wt %
of ~iSi2.or end product characteristics see Table.amPles 92 and 93 Obtaining a cast complex boride
containing 50 wt % o~ MoB, 50 wt %
of ~iB2.or end product characteristics see ~able.
- 20 -
1058841
xamPle 94 Obtaining a cast hard alloy containing
90 wt % of WC, 10 wt % of Mo.
For end product characteristics see ~able.
_ 21 -
-
. ~ 1058841
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