Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PRESSURE REACTOR FOR PRODUCING MATERIALS HAVING
DIRECTED POROSITY
The invention relates to a pressure reactor for producing
materials having directed porosity.
A device known from FR2208743 for producing porous
materials is constructed of a pressure chamber in which a
crucible or a pot is arranged which is placed in a water-
cooled metal mould. The mould is covered from a top with a
cover provided with a gas drain hole and from the bottom it is
provided with an opening for injecting of a gas. The pressure
chamber is fed with a pressurized gas, and a high pressure gas
= is injected into the liquid molten metal placed in the =
crucible. As a result of a gas pressure controlling in the
= pressure chamber, gas saturated metal enters into the mould,
wherein at the same time the gas is evacuated from the
pressure chamber and a solidification of the metal occurs. At
the same time the gas also is released from the metal leaving
pores that are created in this manner. A device known from the
patent US5181549 for producing porous materials comprises .a
pressure autoclave provided with covers and a pressurised gas
supply, inside of which autoclave a crucible or a ladle and a
mould are coaxially permanently mounted. The crucible, which -
is surrounded by a heating element, is provided with an upper
charging door or opening and a bottom drain hole. A layer of
elevated thermal conductivity is arranged in side walls or
bottom wall of the mould. A drain hole is arranged in the
bottom of the crucible, above the mould.. A process for
producing porous materials consists in that the autoclave,
after the crucible is loaded with a charge material, is
supplied with the gas mixture comprising hydrogen. After the
charge material in the crucible is melted, a hydrogen having
determined partial pressure is fed that hydrogen is then
=
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dissolved in the charge material. Subsequently, the molten and
saturated with the hydrogen charge material is discharged
through the drain hole into the mould. In the autoclave during
solidification of the charge material a predetermined gas
pressure is generated and the material solidifies and,
depending on the arrangement and localization of the layer
having higher thermal conductivity, a porous material with
axially oriented pores or radialy oriented pores is obtained.
Summary of the Invention
The pressure reactor according to the invention for
producing materials having directed porosity, consisting of a
pressure chamber provided with a gas inlet valve and covers
detachably connected to it is characteristic by the pressure
chamber connected to the vacuum installation having an
external cooling jacket, wherein further inside of the
pressure chamber, preferably made in a shape of a seamless
tube, a removable and replaceable, retractable, demountable
crystallizer is attached to one its cover, while to the other
cover retractable melting furnace with an internal removable
crucible is attached. A heater having a form of a heating
element encapsulated with insulation in a form of ceramic
beads is provided between the inner housing of the melting
furnace and the crucible. The drain hole of the crucible of
the melting furnace is directed toward the inlet filling hole
of the crystallizer. An intermediate member, preferably in the
form of a conical funnel, is provided between the melting
furnace and the crystallizer. The pressure chamber is mounted
rotatably on a supporting frame in the manner allowing its
rotation around its transverse axis passing through the centre
of the symmetry. Thermoelements are arranged in the melting
furnace and in the crystallizer.
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In accordance with an aspect of the present invention,
there is provided a pressure reactor for producing materials
having directed porosity, the pressure reactor comprising: a
pressure chamber provided with a gas inlet valve and covers
detachably connected thereto, the pressure chamber connected
to a vacuum installation and having an external cooling
jacket; wherein inside of the pressure chamber; a retractable,
removable, demountable crystallizer located inside of said
pressure chamber attached to one of said covers; a retractable
melting furnace with an internal removable crucible attached
to a second cover; a heater in a form of a heating element
encapsulated with an insulation in a form of ceramic beads
provided between an inner housing of the melting furnace and
the crucible, wherein a drain hole of the crucible is directed
in the direction of an inlet filling hole of the crystallizer;
an intermediate element fastened between the melting furnace
and the crystallizer; wherein the pressure chamber is
rotatably mounted in a supporting frame in a manner allowing
its rotation around a transverse axis passing through its
centre of symmetry.
Brief Description of the Drawing
Figure 1 is a cross-sectional view of the pressure
reactor of the invention.
The retractable and removable crystallizer is constructed
in such a manner that the base thereof is made of a material
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having the high thermal conductivity, and the side walls are
made of insulating material or in such a manner that the base
is made of the insulating material and the side walls are made
of a material having high thermal conductivity. The base of
the crystallizer is in direct contact with the cover or an
additional insulating material is provided between the cover
and the base of the crystallizer.
The use of an external cooling jacket prevents overheating
of the pressure chamber, prevents uncontrolled heat losses and
provides precise temperature control, allowing operating the
process under isothermal conditions. Rotation of the apparatus
around its own horizontal axis makes possible to use of the
crucible having only one opening which is designated, first of
all to fill in the crucible with the charge material, and
after following melting of the charge material and rotation of
the pressure chamber, the said opening serves to supply the
crystallizer with liquid metal, allowing for quick and direct
feeding of the crystallizer with liquid metal. During pouring
the melt, an intermediate element between the crystallizer and
the crucible ensures minimum heat loss and also provides a
laminar flow of the metal from the crucible of the furnace
into the crystallizer and prevents splashing of the metal
inside the pressure chamber.
In the pressure reactor for producing materials having
directed porosity according to the invention, thanks to the
construction of the crystallizer being characteristic by
different thermal conductivity of its walls, porous materials
with pores of desired size, shape, and spatial distribution
are obtained. By means of using the removable, replaceable,
demountable and retractable crystallizer and the retractable
melting furnace with the replaceable crucible repeating using
of both these devices is allowed, as well as: easy loading of
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the melting crucible with a charge material, convenient
removal of the resulting product from inside of the
crystallizer and effortless inspection of the apparatus status
which is convenient for the operator are ensured.
The flexible construction of the heater of the crucible
makes possible shaping of the heating element in any desired
manner, and allows to remove the crucible from the melting
furnace.
The use of thermocouples in the melting furnace and in the
crystallizer allows for precise and controlled conducting the
process for producing materials having directed porosity, that
results in significant reduction in the amount of defective
materials and an increase in a quality of the produced
materials.
The device according to the invention is characterized by
safety operation and a stability of casting parameters thanks
to the tight, hermetic chamber that are used and the
isothermicity of the process.
In the pressure reactor for producing materials having
directed porosity according to the present invention porous
materials of plastics, non-ferrous metals, non-ferrous metal
alloys, ferrous alloys and ceramics are cast.
The pressure reactor for producing materials having
directed porosity according to the invention in an embodiment
is presented in the drawing fig.l.
The pressure reactor for producing materials having
directed porosity is constructed of a pressure chamber 1 with
the outer cooling jacket 2. Inside the pressure chamber I made
in the shape of the seamless tube, the removable, demountable
crystallizer 4 is attached to one cover, while to the second
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cover 5 the melting furnace 6 with the inner, removable and
replaceable crucible 7 is attached. The' heater 16 in the form
of a heating element encapsulated with insulation 17 in a form
of ceramic beads is provided between the inner housing of the
melting furnace 6 and the crucible 7. The drain hole 8 of the
crucible 7 is directed towards the filling inlet hole 9 of the
crystallizer 4. The intermediate element 10 in the form of a
conical funnel is fastened between the melting furnace 6 and
the crystallizer 4; which the intermediate element 10 of the
shape of the conical funnel with its larger diameter,adhers to
the drain hole 8 of the crucible 7 and with the smaller
diameter is directed towards the filling hole 9 of the
crystallizer 4. The pressure chamber 1 is provided with a
vacuum valve 19 and a working gas supplying valve 20. The
pressure chamber 1 is mounted rotatably in a supporting frame
11 in a manner allowing its rotation around the transverse
axis passing through its centre of the symmetry. The base 12
of the crystallizer 4 is made of a material having high
thermal conductivity, while the side walls 13 of the
crystallizer 4 are made of insulating material. An additional
insulation material 15 is provided between the base 12 of the
crystallizer 4 and the cover 3. The crucible 7 of the melting
furnace 6 and the crystallizer 4 are equipped with
thermocouples 14 and 18 for measuring the temperature of the
charge material and of the cast material.
A method for producing materials having directed porosity
in a pressure reactor according to the invention:
The melting furnace 6 attached to the cover 5 is moved out
outside of the pressure chamber 1 and some copper is placed in
the crucible 7. The uploaded furnace 6 is then introduced into
the pressure chamber 1 and the cover 5 is screwed on. Then,
the crystallizer 4, the base 12 of which is made of a material
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having high thermal conductivity, is placed in the pressure
chamber 1 and it is screwed down to the cover 3. The pressure
chamber 1 is positioned in such a way that the melting furnace
6 is arranged in the lower part of the chamber while the
crystallizer 4 is located in the upper part of the chamber.
After positioning of the pressure chamber 1 it is connected to
the vacuum system by means of the vacuum valve 19 and the
metal is then subjected to melting in the melting furnace 6.
Following the melting of the copper a gas mixture containing
hydrogen under a pressure of 1 MPa is fed through the valve
20. The copper is saturated with hydrogen for 15 minutes.
After saturation of the copper with the hydrogen, the pressure
chamber 1 is rotated by 180 and in this time, the molten
copper saturated with hydrogen is poured from the crucible 7
of the melting furnace 6 via the intermediate element 10 into
the crystallizer 4. The copper is solidified in the
crystallizer 4 and in the meantime the working gas is
discharged from the pressure chamber 1 through the vacuum
valve 19. The finished cast is removed from the pressure
chamber 1 together with the crystallizer 4. The resulting
porous copper material has pores arranged parallel to the
longitudinal axis of the
crystallizer.
