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 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.

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.

The retractable and removable crystallizer is constructed in such a manner that the base thereof is made of a material 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 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 1 made in the shape of the seamless tube, the removable, demountable crystallizer 4 is attached to one cover, while to the second 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 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.