RU2173354C2 - Method and device for infiltration of gas phase of chemical substance and chemical precipitation from gas phase (versions), article manufactured by said method, device for supply of the first reagent gas to furnace for infiltration and precipitation from gas phase and friction disk - Google Patents

Abstract

FIELD: high-temperature composite materials produced by infiltration of gas phase of chemical substance and precipitation of matrix of binding material in porous structure. SUBSTANCE: invention relates to processes of induced infiltration of reagent gas at pressure gradient, device for realization of these processes and products as a result of these processes by partial compaction of porous structure in furnace at pressure gradient. In this case, the first part of porous structure undergoes pressure higher than the second one. The first part has a higher increment of powder density and subsequent compaction of porous structure by precipitation of other matrix in porous structure with the help of at least one additional compaction process. The second part has increase of powder density higher than in the first one. The invention provides for possibility of simultaneous compaction of large number of porous structure, particularly, blanks for aircraft brake disks. EFFECT: higher efficient of method and device. 77 cl, 29 dwg, 10 tbl

Description

 The invention relates to high-temperature composite materials obtained by infiltration of the gas phase of a chemical substance and the deposition of a matrix of a binder material in a porous structure. More specifically, the present invention relates to methods for forced infiltration of a reactant gas in a porous structure under a pressure gradient, to a device for implementing these methods and to the resulting products.

State of the art
Gas phase infiltration of a chemical substance and chemical vapor deposition is a well-known method of deposition of a matrix of a binder material in a porous structure. The expression "chemical vapor deposition" generally refers to the deposition of a surface coating, but this expression is also used in relation to the infiltration and deposition of a matrix of a binder material in a porous structure. In this application, the expression “gas phase infiltration of a chemical substance and chemical vapor deposition” refers to the infiltration and deposition of a matrix of a binder material in a porous structure. This technology is particularly suitable for producing high-temperature composite materials by depositing a carbon or ceramic matrix in a carbon or ceramic porous structure, resulting in very useful structures such as carbon / carbon aviation brake discs and ceramic components of a combustion chamber or turbine. Known methods of gas phase infiltration of a chemical substance and chemical vapor deposition can be divided into four groups: isothermal, with a temperature gradient, with a pressure gradient and with a pulsating flow. (See the work of V.V. Kotlensky, Deposition of pyrolytic carbon in porous bodies, 8 Chemistry and Physics of Carbon, 173, 190-203 (1973); V.J. Lucky, Review, current state and future of the method of chemical gas phase infiltration substances for the preparation of fiber-reinforced ceramic composite materials, Ceram. Eng. Sci. Proc. 10 [7-8] 577, 577-81 (1989) (W.J. Lucky refers to the process with a pressure gradient as "isothermal forced flow" ). In the isothermal method of gas phase infiltration of a chemical substance and chemical vapor deposition of a gas The entrant passes into a heated porous structure at absolute pressures of the order of several thousandths of a millimeter of mercury. This gas diffuses into the porous structure under the influence of concentration gradients and decomposes to precipitate a matrix of a binder material. This method is also known as the "standard" method of gas phase infiltration of a chemical substance and chemical vapor deposition. The porous structure is heated to a more or less uniform temperature (in connection with this, the term "isothermal" arose), but in fact this is not true. Some temperature deviations in the porous structure are unavoidable due to uneven heating (essentially unavoidable in most furnaces (heaters)), cooling of some parts due to the flow of the reactant gas, and heating or cooling of other parts due to the heat of the reaction processes. Essentially, the term "isothermal" means that there is no attempt to create a temperature gradient that would preferably affect the deposition of a matrix of a binder material. This method is well suited for the simultaneous compaction of a large number of porous products and is particularly suitable for the manufacture of carbon / carbon brake discs. Under appropriate process conditions, a matrix having the desired physical properties can be precipitated. However, with the standard method of gas phase infiltration of a chemical substance and chemical vapor deposition, continuous deposition can occur for several weeks to achieve an acceptable density and the surface will tend to become denser, leading to the formation of a "tight coating" that prevents further gas infiltration - reagent into the internal areas of the porous structure. Thus, this technology typically requires several surface machining operations that disrupt the continuity of the compaction process.

 In the method of gas phase infiltration of a chemical substance and chemical vapor deposition at a temperature gradient, the porous structure is heated so as to create large temperature gradients that promote deposition in the desired portion of the porous structure. Temperature gradients can be obtained by heating only one surface of the porous structure, for example, by placing the surface of the porous structure opposite the wall of the current collector (induction currents), and can be increased by cooling the opposite surface, for example, by placing the opposite surface of the porous structure against the wall, cooled by the liquid. The deposition of a matrix of a binder material develops from hot to cold surfaces. The need to create a temperature gradient complicates, increases the cost and complicates the simultaneous compaction (increase in density) of a large number of porous structures.

 In the method of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, the reactant gas is forced to pass through the porous structure by creating a pressure gradient from one surface of the porous structure to the opposite surface of the porous structure. The flow rate of the reactant gas is much greater than the speed of the reactant gas in the isothermal method and the method carried out at a temperature gradient, which leads to an increase in the deposition rate of the matrix of the binder material. This method is also known as a method of gas phase infiltration of a chemical substance and chemical vapor deposition with a "forced flow". Prior to the development of such a method of gas phase infiltration of a chemical substance and chemical vapor deposition, the simultaneous densification of a large number of porous structures was difficult, expensive, and difficult to implement. An example of a method in which a longitudinal pressure gradient is created along a bundle of unidirectional fibers is described by S. Kamura, N. Takase, S. Kasui and E. Yazuda, Cracking of a carbon fiber / carbon composite material obtained by chemical vapor deposition, Carbon '80 (German Ceramic Society) (1980). An example of a method in which a pressure gradient is created only in the radial direction to seal an annular wall is described in US Pat. Nos. 4,212,906 and 4,134,360. The annular porous wall described in these patents can be formed from a large number of annular disks assembled in a bag (for manufacture of disc brakes) or may be a unitary tubular structure. For thick-walled structural composite materials, a purely radial pressure gradient creates a very large undesirable density gradient, ranging from the inner cylindrical surface to the outer cylindrical surface of the annular porous wall. The surface subjected to high pressure also tends to compact very quickly, leading to its sealing, which prevents the passage of the reagent gas in the low-density region. This behavior significantly limits the usefulness of the method, carried out with a purely radial pressure gradient.

 And finally, the pulsating flow provides for quick and cyclical filling and pumping of the chamber containing the heated porous structure with a reagent gas. The cyclic action causes the reactant gas to penetrate into the porous structure and also remove by-products of the decomposition of the reactant gas from the porous structure. The equipment for carrying out such a process is complex, expensive and inconvenient to operate. Such a process is very difficult to carry out to simultaneously seal a large number of porous structures.

 Many developers in this technical field have combined a method carried out with a temperature gradient and a method carried out with a pressure gradient, resulting in a method carried out with a temperature gradient and forced flow. The combination of methods eliminates the disadvantages characteristic of each individual method and results in very fast compaction of porous structures. However, the combination of methods doubles the complexity, since in this case equipment and technology must be provided to create both a temperature gradient and a pressure gradient with some degree of regulation. The method of sealing small discs and pipes, carried out in accordance with the process with a temperature gradient and forced flow, is described in US patent N 4580524 and A.J. Caputo and W.J. Varnishes, Obtaining reinforced fibers of ceramic composite materials by gas phase infiltration of a chemical substance was performed at OAK RIDGE NATIONAL LABORATORY for U. S. DEPARTMENT OF ENERGY under contract N DE-AD05-840R21400 (1984). In accordance with this method, the fiber preform was placed in a water-cooled jacket. The upper part of the preform was heated and the gas was forced to pass through the preform to the heated part, where it decomposed and precipitated the matrix. A method for depositing a matrix in a tubular porous structure is described in US Pat. No. 4,895,108. In accordance with this method, the outer cylindrical surface is heated and the inner cylindrical surface is cooled by a water jacket. The reactant gas was supplied to the inner cylindrical surface. Similar methods carried out under forced flow and at a temperature gradient, designed to obtain various products, are described by T. Khan, C.V. Burkland and B. Bustamant in the work "Sealing thick disk blanks with a silicon carbide matrix by infiltration of the chemical phase gas phase", Ceram. Eng. Sci. Proc. 12 [9-10] pp. 2005-2014 (1991); T.M. Bestman, R.A. Lowden, D.P. Stinton and T.L. Starr in "Method for the rapid infiltration of the gas phase of ceramic composite materials", Journal De Physique, Colloque C5, supplement au n'5, Tome 50 (1989); T.D. Guilder, J.L. Kay and K.P. Norton in "Gas-phase Infiltration (Forced Flow and Temperature Gradient) of Ceramic Matrix Composite Materials", Proc. -Electrochemical Society (1990), 90-12 (Proc. Int. Conf. Chem. Vap. Deposition, 11th, 1990) 546-52. Each of these works describes the compaction processes of only one porous product at a time, which are impractical for the simultaneous processing of a large number of products from composite materials, such as brake discs, carbon / carbon.

 Despite the described advantages, there is a need for a method for gas phase infiltration of a chemical substance and chemical vapor deposition and a device for implementing this method, which would allow porous structures to be quickly and uniformly compacted while minimizing cost and complexity. Preferably, such a method allows the simultaneous compaction of a large number (for example, hundreds) of individual porous structures. In particular, there is a need for a method for quickly and cost-effectively simultaneously sealing a large number of structures of annular fiber preforms for aircraft brake discs having the required physical properties.

SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a method for infiltrating a gas phase of a chemical substance and chemical vapor deposition, comprising:
partial compaction of the porous structure in the furnace (thermal apparatus) for gas phase infiltration of the chemical substance and chemical vapor deposition by deposition of one matrix in the porous structure using the gas phase infiltration of the chemical substance and chemical vapor deposition under the pressure gradient, the first part the porous structure is subjected to a higher pressure than the second part of the porous structure, and the first part has a higher bulk density increment than W Paradise part; and
subsequent densification of the porous structure by deposition of another matrix in the porous structure using at least one additional densification process, the second part having a higher increase in bulk density than the first part.

In accordance with another aspect of the present invention, there is provided a method for infiltrating a gas phase of a chemical substance and chemical vapor deposition, comprising:
partial densification of a large number of annular fibrous carbon structures in a furnace for gas phase infiltration of a chemical substance and chemical vapor deposition by deposition of a first carbon matrix in an annular fibrous carbon structure using a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient, moreover, the first part of each annular fibrous carbon structure is subjected to a higher pressure than Thoraya portion of each annular fibrous carbon structures, and this first portion has a higher increase in bulk density than the second portion; and
subsequent densification of a large number of annular fibrous carbon structures by deposition of a second carbon matrix in each annular fibrous carbon structure using at least one additional densification process, the second part having a higher increase in bulk density than the first part.

In accordance with another aspect of the present invention, a friction disc is claimed having
a compacted annular porous structure having a first carbon matrix deposited in the annular porous structure and a second carbon matrix deposited in the annular porous structure on top of the first carbon matrix, the compacted annular porous structure having two generally parallel flat surfaces connected by an inner annular surface and an outer annular surface spaced from the inner annular surface and surrounding it; the first annular part is adjacent to the inner annular surface, and the second annular part is adjacent to the outer annular surface, while the first and second annular parts are connected by two generally parallel flat surfaces, the second annular part has at least 10% less carbon matrix per unit volume than the first ring portion, wherein the first and second carbon matrices have a substantially coarse layered microstructure, the first carbon matrix being more graphitized than the second carbon matrix.

In accordance with another aspect of the present invention, a method for infiltrating a gas phase of a chemical substance and chemical vapor deposition in a furnace for infiltrating a gas phase of a chemical substance and chemical vapor deposition is provided, comprising
introducing a reagent gas into a sealed heater located in the furnace for gas phase infiltration of a chemical substance and chemical vapor deposition and having an inlet and an outlet, and the reagent gas is introduced into the inlet of the heater and removed from the sealed heater through the outlet and scattered through at least one porous structure located in a furnace for infiltration of a gas phase of a chemical substance and chemical vapor deposition;
heating at least one porous structure;
heating the sealed heater to a temperature that is higher than the temperature of the reactant gas;
measuring the gas temperature of the reagent gas near the outlet;
regulating the temperature of the heater to achieve the desired gas temperature;
and discharging the reactant gas from the furnace to infiltrate the gas phase of the chemical substance and chemical vapor deposition.

In accordance with another aspect of the present invention, there is provided a device for introducing a first reactant gas into a furnace for infiltrating a gas phase of a chemical substance and chemical vapor deposition, comprising
a first gas pipeline for supplying a first reagent gas;
furnace feed lines in communication with the first gas main and furnace for infiltration of the gas phase of the chemical substance and chemical vapor deposition;
first flowmeters measuring the flow rate of the first reactant gas through each furnace feed line; and
first control valves designed to control the flow rate of the first reactant gas through each furnace feed line.

In accordance with yet another aspect of the present invention, there is provided a method of densification by gas phase infiltration of a chemical substance and chemical vapor deposition, comprising
compaction of the first porous wall in the furnace for infiltration of the gas phase of the chemical substance and chemical deposition from the gas phase at a pressure gradient, wherein the first reagent gas stream is scattered through the first porous wall;
densification of the second porous wall using a gas phase infiltration process of a chemical substance and chemical vapor deposition at a pressure gradient, the second reagent gas stream being scattered through the second porous wall; and
independent control of the first reagent gas stream and the second reagent gas stream.

List of drawings
FIG. 1 is a schematic representation of a furnace for gas phase infiltration of a chemical substance and chemical vapor deposition according to the present invention.

 FIG. 2 is a cross-sectional view of a retainer for effecting gas phase infiltration of a chemical substance and chemical vapor deposition in accordance with an aspect of the present invention.

 FIG. 3-7 are a sectional view of a latch according to the present invention.

 FIG. 8-13 are sectional views of a densified structure according to the present invention.

 FIG. 14 is a schematic representation of a furnace for a standard process for gas phase infiltration of a chemical substance and chemical vapor deposition.

 FIG. 15 is a schematic diagram of a furnace for simultaneously densifying a large number of porous structures by gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient according to the present invention.

 FIG. 16 is an isometric view of a heater according to the present invention.

 FIG. 17 is an isometric view of a retainer with porous structures according to the present invention.

 FIG. 18 is a view of a retainer with porous structures according to the present invention.

 FIG. 19-21 are schematic diagrams of a method according to the present invention.

 FIG. 22 is another embodiment of a flat cap for use with the heater shown in FIG. 16.

 FIG. 23 is a cross-sectional view of a densified structure according to the present invention.

 FIG. 24 is a graph of bulk density versus time for several processes of the present invention.

 FIG. 25 is a graph of average deposition rate versus predetermined reagent gas flow rate for several processes of the present invention.

 FIG. 26 is a graph of average deposition rate versus predetermined reagent gas flow rate for various pressures in the reactor volume according to the present invention.

 FIG. 27 is a graph of pressure change across a porous wall versus average bulk density for various reagent gas flows and pressures in the reactor volume according to the present invention.

 FIG. 28 is a partially cutaway retainer for holding porous structures having alternating ring-shaped gaskets along the outer and inner diameters.

 FIG. 29 is a partially cutaway retainer for holding porous structures having all ring-shaped gaskets in inner diameter.

Information confirming the possibility of carrying out the invention
The present invention and various embodiments thereof are shown in FIG. 1 -29, where similar elements are indicated by the same reference numbers, and an accompanying description. Used in this application, the expression "standard process of gas phase infiltration of a chemical substance and chemical vapor deposition" refers to the method described above for isothermal gas phase infiltration of a chemical substance and chemical vapor deposition. The expression "process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient" refers to the method described above for gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient or to a method carried out under forced flow and is intended to replace exceptions to the methods described above carried out under a temperature gradient and forced flow to the extent that deliberately used a given temperature gradient that affects the deposition process.

 In FIG. 1 is a schematic illustration of a furnace 10 for gas phase infiltration of a chemical substance and chemical vapor deposition configured to deposit a matrix in a porous structure 22 during a gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient according to the present invention. The furnace 10 comprises a casing 13 having an inner surface 12 that limits the volume 14 of the furnace, a gas inlet 16 for introducing gas into the furnace 10. The current collector 30 (induction currents) is located around the volume 35 of the reactor and is heated by induction by the inductor 20 in accordance with methods that are good known in the art. Other heating methods, such as resistive heating or microwave heating, may also be used, with each heating method appearing to be within the scope of the present invention. An insulation layer 31 is located between the current collector 30 and the inductor 20. The current collector 30 has an inner surface 33 that limits the volume 35 of the reactor located in the volume 14 of the furnace. The porous structure 22 is located in the retainer 2 in the reactor volume 35 and is predominantly heated by radiation from the current collector 30. The vacuum device 58, containing a vacuum pump or a steam-vacuum system, communicates with the exhaust pipe 32 and is designed to pump the furnace volume 14 to a pressure below atmospheric. The reagent gas is introduced into the reactor volume 35 through the gas inlet 16 from the inlet pipe 26 of the furnace. The reagent gas is infiltrated through the porous structure 22, where it decomposes and precipitates the matrix in the porous structure 22. One or more types of gases can be supplied to the gas inlet 16.

 According to a preferred embodiment, the reagent gas comprises a mixture of two reagent gases which are introduced through the first main gas line 42 and the second main gas line 44. The furnace supply pipe 26 communicates with the first and second main gas lines 42 and 44 and the gas pipe 16, providing with this, the supply of reagent gases to the furnace 10. The first flow meter 46 measures the flow rate of the first gas (shown by arrow 50) supplied to the furnace feed pipe 26 through the first gas main od 42, and the second flow meter 48 measures the flow rate of the second gas (indicated by arrow 52) supplied to the furnace feed line 26 through the second gas pipeline 44. The gas flow rate in the furnace feed pipe 26 is controlled by a first control valve 54 that controls the flow of the first reactant gas from the first main gas pipeline 42, and the second control valve 56, which regulates the flow of the second reagent gas from the second main gas pipeline 44.

 The porous structure 22 contains an opening 23. The tube 60 communicates with the retainer 2, providing a reagent gas to the retainer 2. The retainer contains a pair of plates 38 and 40, and the tube 60 is sealed with a gas inlet 16 and with a plate 38. The porous structure 22 is sealed between the annular plates gaskets 62 and 64 along the inner and outer diameters, respectively, and the plates 38 and 40 are connected by tie rods 66. The porous structure 22 forms a porous wall 68 located between the gas inlet 16 and the exhaust pipe 32. The furnace volume 14 and the reactor volume 35 from pumped to a pressure below atmospheric, and gas is supplied through the opening 23 of the porous structure at a higher pressure than the pressure in the volume of the reactor, which creates a pressure gradient through the porous wall 68 and provides forced dispersion of the gas through the porous structure before it is removed from the volume 35 of the reactor and furnace volume 14 by means of a vacuum device 58, as shown by arrows 34, 36 and 28.

 The pressure inside the furnace volume is measured by the outlet pressure sensor 72, and the pressure in the opening of the porous structure 23 is measured by the intake pressure sensor 70. The approximate temperature of the reactant gas in the hole 23 of the porous structure is measured by the temperature sensor 74 of the flow, and the temperature of the porous structure is approximated by the temperature sensor 76 of the structure, which is located in the immediate vicinity of the plate 40. As will be described in more detail, the temperature and pressure parameters are chosen such so that the gas decomposes and precipitates a matrix having certain desired properties in the porous structure 22. Various aspects of the present invention can be used to I matrix deposition of any type, obtained by gas phase chemical infiltration and chemical vapor deposition, including but not limited to, carbon or ceramic matrix deposited in porous structures 22 or carbon-based ceramic. The present invention is particularly suitable for deposition of a carbon matrix in a carbon-based porous structure, and mainly for the production of carbon / carbon composite structures, such as aircraft brake discs.

 In FIG. 2 is a detailed view of the retainer 2 for holding the porous structure 22. According to a preferred embodiment, the porous structure is annular and has two opposed, generally planar surfaces 78 and 80 that are connected by an inner annular surface 82 and an outer annular surface 84. The annular an outer diameter gasket 64 having an average diameter smaller than the diameter of the outer annular surface 84 is located between the porous structure 22 and the plate 38. The annular a second gasket 62 in internal diameter, having an average diameter slightly larger than the diameter of the inner annular surface 82, is located between the porous structure 22 and the plate 40. The annular gaskets 62 and 64 also serve to allow gas flow between the porous structure 22 and the plates 38 and 40, as well as for sealing the porous structure 22 with plates 38 and 40. The tie rods 66 can be threaded at one or both ends and have nuts 67 screwed on them. For load balancing on the plates 38 and 40 washers 69 may be used.

 As described above, the furnace volume is pumped out using a vacuum pump and the reagent gas is introduced into the tube 60 at a higher pressure than the pressure in the furnace volume. Thus, the first part 86 (indicated by the dashed line) of the fibrous structure 22 is subjected to a higher pressure than the second part 88 (indicated by the thin dashed line) of the fibrous structure 22, which creates the dispersion of the reactant gas through the porous structure 22, as indicated by arrows 90. When the gas is scattered through the porous structure, an additional gas stream passes through the pipe 60 to the porous structure 22, as indicated by arrows 92. Thus, the reactant gas is continuously supplied and forcedly scattered through the pores. the true structure 22. In this example, the first part 86 has a surface 78, and the second part 88 has another opposite surface 80. The first part 86 also has an inner annular surface 82, and the second part 88 has an outer annular surface 84.

 In FIG. 3 shows an alternative retainer 4 (which can be used instead of retainer 2) in which two porous structures 22 are packaged and sealed at the same time. In this case, two annular gaskets 64 and tie rods 65 are used, which are similar to tie rods 66 shown in FIG. . 2, but having a large length. A pressure gradient is applied to the porous structure (as described above with reference to Fig. 2), leading to the dispersion of the reactant gas through the porous structure, as indicated by arrows 90. Other elements of the retainer 4 are identical to the elements of the retainer 2.

 The reactant gas tends to decompose and is preferably deposited as a matrix in parts of the porous structure 22, which are subjected to a relatively higher pressure than the pressure in other parts. For example, in FIG. 8 shows a densified structure 300, structure 22, which is obtained using the processes shown in FIG. 2 and FIG. 3. The relative density corresponds to the density of the hatching: finer shaded areas have a higher density than the larger shaded areas. The density decreases monotonically from zone 302 having the highest density to zone 308 having the lowest density, with zones 304 and 306 having an intermediate density. The densified structure 300 has an average bulk density, with zone 302 having a density of typically 110-140% of the average bulk density, and zone 308 has a density of typically 60-90% of the average bulk density. It should be noted that the zone 302 of the highest density, as a rule, corresponds to the first part 86, and the zone 308 of the lowest density, as a rule, corresponds to the second part 88. Thus, in the process of gas phase infiltration of a chemical substance and chemical vapor deposition, shown in FIG. 2 and 3, the first part 86 has a greater increase in bulk density than the second part 88.

 The density gradient shown in FIG. 8 is not acceptable for many applications. The density gradient can be reduced by deposition of the first matrix in the porous structure by the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient, as shown in FIG. 2 and 3. In this first process, the first part 86 has a greater increase in bulk density than the second part 88, as shown in FIG. 8. After this, the porous structure 22 can be further densified by deposition of the second matrix during at least one additional densification process, during which the second part 88 has a greater increase in bulk density than the first part 86. For example, the partially sealed structure 300, shown in FIG. 8 can be inverted and subjected to a process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient shown in FIG. 2 and 3. The second part 88 is subjected to a higher pressure than the first part 86, which leads to the fact that the second part 88 has a greater increase in bulk density than the first part 86. In FIG. 9 shows a densified structure 310 obtained by such a two-step process carried out by inverting a porous structure. The density decreases monotonically from the highest density zone 312 to the lowest density zone 316, with zone 314 having an intermediate density. The densified structure 310 has an average bulk density, and the density zone 312 has a bulk density, typically 105-115% of the average bulk density, and the density zone 316 has a bulk density, typically 85-95% of the average bulk density density. The density gradient in this case, as a rule, is symmetrical in thickness of the porous structure 22, which is desirable in the manufacture of brake discs. This density gradient is also smaller than the density gradient of the densified structure 300 shown in FIG. 8. Other or additional processes may include gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient, a standard process for gas phase infiltration of a chemical substance and chemical vapor deposition, and resin impregnation after carbonization. In addition, in order to increase the graphitization of the carbon matrix before the additional matrix is deposited, the porous structure, partially densified by the carbon matrix, can be subjected to heat treatment at a temperature higher than the operating temperature of the previous processes of gas phase infiltration of a chemical substance and chemical vapor deposition.

 In FIG. 4 shows another alternative retainer 6, which can be used instead of retainer 2 for another process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient. The latch 6 has an annular gasket 62, the inner diameter, which leads to the fact that only the inner annular surface 82 of each porous structure is subjected to a higher pressure than the pressure in the volume of the reactor 35. Thus, the first part 87 of the porous structure 22 is subjected to a higher pressure than the second part 89. This causes the reagent gas to flow through the porous structures under pressure, as indicated by arrows 91. In this example, the first part 87 has an inner annular surface 82, and the second part 89 has an outer annular surface 84 and two opposite surfaces 78 and 80. The reactant gas has the ability to quickly pass through the porous structure 22 and exit near the annular gasket 62. Thus, the reagent gas is not forced to disperse through the entire porous structure 22. FIG. 10 shows the densified structure 320 obtained by implementing the process illustrated in FIG. 4. The sealed structure 320 has a zone 322 of the highest density located adjacent to the inner annular surface 82, and the density decreases to the zone 328 of the lowest density located in the middle. The density monotonically increases from the zone 328 of the lowest density to the zone 322 of the highest density, and zones 324 and 326 are regions having intermediate density values. The densified structure 320 has an average bulk density, and zone 322 typically has a bulk density of approximately 140% of the average bulk density, and zone 324 typically has a bulk density of approximately 115% of the average bulk density. Zone 328 typically has a bulk density of approximately 80% of the average bulk density. The highest density zone 322 typically corresponds to the first portion 87 shown in FIG. 4. An intermediate density region 324 adjacent to the outer annular surface 84 is formed using a standard gas phase infiltration process of a chemical substance and chemical vapor deposition by means of a reagent gas that is not completely decomposed leaving the adjacent porous structures. The densified structure 320 may be further densified by other or additional densification processes, which include a gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, a standard chemical vapor phase infiltration process, and chemical vapor deposition and impregnation resin after carbonization.

 In FIG. 5 illustrates an alternative fixative 8, which can be used instead of fixative 2 for an alternative process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient. The latch 8 has an annular gasket 64, in outer diameter, causing the inner annular surface 82 and the opposite surfaces 78 and 80 of each porous structure to be subjected to a higher pressure than the pressure in the reactor volume 35. The outer annular surface 84 is subjected to pressure of the volume of the reactor 35. Thus, the first part 94 of the porous structure 22 is subjected to a higher pressure than the second part 96. This leads to the fact that under the influence of pressure there is a movement of the flow of the reagent gas through the porous structures 22, as indicated by arrows 98. In this example, the first part 94 has an inner annular surface 82 and opposite surfaces 78 and 80, and the second portion 96 has an outer annular surface 84. As shown, the reactant gas is dispersed through the entire porous structure 22. FIG. 11 shows the densified structure 330 obtained by the process illustrated in FIG. 5. The densified structure 330 has a zone 332 of highest density adjacent to the inner annular surface 82, and a part consisting of two opposite surfaces 78 and 80. The zone 332 sometimes extends to the outer annular surface 84 and contains substantially completely opposite surfaces 78 and 80. Density monotonously decreases from zone 332 of highest density to zone 338 of lowest density, with zones 334 and 336 having intermediate densities. The densified structure 330 has an average bulk density, with a density zone 332 typically having a density of 110-125% of the average bulk density, and a zone 338 typically has a density of 80-90% of the average bulk density. The process illustrated in FIG. 5 makes it possible to obtain a densified structure 330 that has a symmetric density gradient across the thickness of the structure. However, in some densified structures 330, the density gradient may shift to one of the surfaces 78 or 80 due to deviation of the process parameters. It should be noted that zones 332 and 334 typically correspond to the first part 94 shown in FIG. 5, and the second part 96 has a relatively lower increase in density, as shown by zones 336 and 338. The densified structure 330 may be further densified by other or additional densification processes, which include the gas phase infiltration of the chemical and chemical vapor deposition phase with a pressure gradient, a standard process of gas phase infiltration of a chemical substance and chemical vapor deposition and resin impregnation after carbonization.

 In FIG. 12 shows a densified structure 340, which is obtained by additionally sealing the porous structure 330 illustrated in FIG. 11, using a standard gas phase infiltration process of a chemical substance and chemical vapor deposition. As shown, the highest density occurs in area 342, adjacent inner annular surface 82, which remains from area 332 shown in FIG. 11. The subsequent standard process for gas phase infiltration of a chemical substance and chemical vapor deposition reduces the density gradient in the radial direction. This is shown by the intermediate density zone 344 adjacent to the outer annular surface 84. The lower density zone 346 surrounds the central lowest density zone 348. The subsequent process densifies the parts of lower density remaining in the densified structure 330 shown in FIG. 11. Thus, the second part 96 shown in FIG. 5, during the subsequent standard process of gas phase infiltration of a chemical substance and chemical vapor deposition, has a higher increase in bulk density than the first part 94. In addition, the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient, carried out as shown in FIG. 5 makes it possible to obtain the desired porosity distribution in the densified structure 330, which makes it extremely sensitive to subsequent densification using standard processes of gas phase infiltration of a chemical substance and chemical vapor deposition. The densified structure 330 rather reaches the final density and has a minimal tendency to become denser during subsequent standard processes of gas phase infiltration of a chemical substance and chemical vapor deposition than a structure having the same bulk density that was previously densified only by standard processes of chemical gas infiltration substances and chemical vapor deposition. This greatly reduces the need for surface machining during subsequent processes, which greatly simplifies and speeds up the entire compaction process. This synergistic effect was a startling discovery.

 In FIG. Figure 6 shows an alternative fixative that can be used instead of fixative 2 for an alternative process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient. The process illustrated in FIG. 6 is a “reverse flow” process in which the reactant gas enters the porous structure from the outside rather than from the inside of the porous structure 22. This process is carried out by placing the porous structure 22 between the plates 38 and 41. The plate 41 is essentially identical to the plate 40 behind except that the plate 41 has an opening 43. An insulating cylinder 350 surrounds the porous structure 22, is located between the plates 38 and 41 and sealed with them. The peripheral part of the surface 80 is separated from the plate 41 and sealed with it by means of an annular gasket 64 along the outer diameter. The peripheral part of the surface 78 is separated from the sealing plate 352 and sealed with it by an annular gasket 64 on the outer diameter, the sealing plate 352 being located between the porous structure 22 and the plate 38. A certain number of spacer sleeves 353 provides a gap between the sealing plate 352 and the plate 38, forming a number of holes 354. The reagent gas is supplied to the retainer 9 in the direction of arrow 92. By means of the sealing plate 352, the gas flow passes radially outward through the holes 354. Then, through the insulating cylinder 350, the gas flow passes upward, as shown by arrows 356 to the outer annular surface 84 of the porous structure 22. The hole 43 in the plate 41 communicates the inner region of the retainer with the furnace volume and is under pressure that is less than the pressure of the gas supplied through the tube 60. Thus, the first part 95 is subjected to a higher pressure than the second part 97, which causes the gas to disperse through the porous structure 22, as shown by arrows 99. The gas exits and 9 into the reactor volume 35 through the opening 43, as shown by arrow 358. In this example, the first part 95 has an outer annular surface 84 and the second part 97 has an inner annular surface 82 and opposite surfaces 78 and 80. The sealed structure may be further sealed with using other or additional densification processes, which include the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, a standard chemical gas phase infiltration process eskogo substances and chemical deposition from the vapor phase and impregnation with resin after carbonization.

 In FIG. 7 illustrates an alternative fixative 7 that can be used instead of fixative 2 for an alternative process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient. FIG. 7 illustrates a reverse flow process that is very similar to the process shown in FIG. 6. The latch 7 is essentially identical to the latch 9 except that the latch 7 contains ring-shaped gaskets 62 in inner diameter, and not ring-shaped gaskets 64 in outer diameter. The reagent gas stream enters through opposing surfaces 78 and 80 and the outer annular surface 84, and exits the inner annular surface 82 of the porous structure 22, as shown by arrows 101. The inner annular surface 82 is under pressure from the reactor volume 35, and the outer annular surface 84 and opposing surfaces 78 and 80 are exposed to pressure of the supplied reactant gas. Thus, the first part 552 of the porous structure 22 is subjected to a higher pressure than the second part 550. In this example, the second part 550 has an inner annular surface 82, and the first part 552 has an outer annular surface 84 and opposite surfaces 78 and 80. In FIG. . 13 illustrates the densified structure 341 obtained by the process shown in FIG. 7. The densified structure 341 has a zone 343 of the highest density adjacent to the outer annular surface 84, and a part consisting of two opposite surfaces 78 and 80. The density monotonously decreases from the zone 343 of the highest density to the zone 349 of the lowest density, and zones 345 and 347 have an intermediate density. The densified structure 341 has an average bulk density, wherein zone 343 typically has a density of approximately 120% of the average bulk density, and zone 349 typically has a density of 80% of the average bulk density. The densified structure 341 may be further densified by other or additional densification processes, which include a gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, a standard chemical gas infiltration process, and chemical vapor deposition and impregnation resin after carbonization.

The various elements of the clips 2, 4, 6, 7 are preferably made of graphite, but any highly heat-resistant material can be used from the practice of the present invention. Various compounds can be sealed with elastic seals and / or liquid adhesives, such as graphite cement. The porous structure may be pressed against the annular gaskets to form adequate seals if the porous structures are pliable prior to sealing. Suitable spacers may be formed from a flexible graphite such as a flexible graphite sheet family EGC Thermafoil ^®, supplied EGC Enterprises Incorporated, Mentor, Ohio, USA, sealants and tape supplied from UCAR Carbon Company Inc., Cleveland, Ohio , USA.

The standard process of gas phase infiltration of a chemical substance and chemical vapor deposition can be carried out
using the furnace 11 shown in FIG. 14. The furnace 11 is very similar to the furnace 10 (see Fig. 1). However, the retainer 2 is replaced by a retainer 360 containing a support plate 362 located on the support legs 364. The porous structure is mounted on gaskets 368 that separate the porous structure 22 from the plate 362, allowing reagent gas to pass between the plate 362 and the porous structure 22. Support plate 362 has a large number of holes (not shown) to allow dispersion of the reagent gas through the plate and around the porous structure 22. The support posts 364, gaskets 368, and the support plates 362 with holes are preferably made of gr afita. Tube 60 illustrated in FIG. 1 is replaced by a pipe 366 having a larger diameter. Gas enters the furnace volume and expands freely, as shown by arrows 370. Gas passes over the porous structure, as shown by arrows 34, and leaves the furnace volume 14 into a vacuum device 58, as shown by arrows 36 and 28. Usually, only one temperature sensor 76 is used , which measures the total temperature of the porous structure 22. The pressure measured by the pressure sensor 70 is only slightly larger than the pressure measured by the sensor 72 during the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition phase. The reagent gas mixture may be introduced from the gas pipelines 42 and 44, as described above with reference to FIG. 1.

 For each of the clips shown in FIG. 2 to 7, each annular porous structure 22 has a surface area, a slightly larger part (more than 50%) of it is exposed to the reactant gas when it enters or leaves the porous structure 22. A high level of exposure reduces the pressure gradient required for forced dispersion gas through each porous structure. It is preferable to expose the reactant gas to as large a surface area of the porous structure as possible. Preferably, at least 80% of the surface area of the porous structure is exposed.

 In FIG. 15 shows a furnace 400 for infiltrating a gas phase of a chemical substance and chemical vapor deposition and a device 402 for supplying a first reactant gas to a furnace 400. The furnace 400 and device 402 are particularly suitable for simultaneously sealing a large number of porous articles, for example from five hundred to a thousand annular blanks for the production of aviation brake discs. The first main gas pipeline 404 delivers the first reagent gas, as shown by arrow 406. The furnace supply lines 408 communicate with the first gas main 404 and the furnace 400. The first flow meters 410 measure the flow rate of the first reactant gas through each furnace supply pipe 408. The first control valves 412 are designed to control the flow rate of the first reactant gas through each furnace feed line 408. The device 402 comprises four inlet lines 408, four control valves 412, and four flow meters 410, but the present invention is not limited to the use of such a number of elements since it can be more or less in accordance with the requirements of a particular application.

 According to a preferred embodiment, the furnace 400 and the reagent gas supply device 402 are controlled by a controller 414. Each flow meter 410 can transmit flow measurement data to the controller 414 via a first flow measurement data line 416, and the controller 414 can control each control valve 412 along line 418 of control of the first valve. Thus, for each supply pipe 408, the flow rate of the first reactant gas in the furnace 400 can be independently set and adjusted. The controller 414 is preferably microprocessor-based and has a screen 415 for displaying various control parameters and states in the reactant gas supply device 402 and the furnace 400. In accordance with a specific embodiment, each furnace feed line 408 includes one first flow meter 410 and one first control valve 412, as shown in FIG. 15, as well as the first main control valve 420 located in the first main gas pipeline 404, preferably for regulating the pressure therein. The first main flow meter 422 may also be located in the first main gas pipeline 404.

 A gas mixture may be supplied to the furnace 400 by performing at least a second gas main 424 for supplying a second reactant gas, as indicated by arrow 426. Second flowmeters 430 are provided that measure the amount of flow of the second reactant gas through each furnace feed line 408, with second control valves 432, designed to control the flow rate of the second reactant gas through each furnace inlet pipe 408. Each flowmeter 430 can transmit flow measurement data to a controller 414 via a second flow measurement data line 436, and a controller 414 can control each control valve 432 via a second valve control line 438. According to a particular embodiment, the second gas pipeline 424 comprises a second gas control valve 440 located in the second gas pipeline 424. The second gas flow meter 442 may also be located in the second gas pipeline 424. The second gas control valve 440 preferably controls the pressure in the second gas pipeline 424.

 The furnace 400 comprises a furnace casing 444 that limits the volume 446 of the furnace. In a furnace volume 446 is a reactor volume 447. The furnace feed lines 408 communicate with a reactor volume of 447. The vacuum device 448 communicates with the furnace volume 446 and the reactor volume 447 through exhaust pipes 450. The vacuum device 448 reduces the pressure in the furnace volume 446 to below atmospheric pressure and may contain any suitable apparatus, for example, a vacuum pump or a steam-vacuum system with appropriate filters and gas scrubbers, which remove unwanted by-products from the reagent gas used. The reagent gas supplied from this furnace feed line 408 enters the corresponding heater 458. The first heater 458 is located in the reactor volume 447 and has an inlet 460 and an outlet 461. The first heater 458 is sealed so that substantially all of the reagent gas fed through the inlet 460 from the corresponding furnace inlet 408, was heated and exited the heater through the corresponding outlet 461, where it is infiltrated through at least one porous structure, p laid in the oven. The expression “substantially all gas” refers to minor leaks. The first heater 458 has a temperature that exceeds the temperature of the reactant gas in the corresponding furnace feed line 408. The porous structure is also heated. In this example, the porous structure has a first porous wall 452 located in the volume 447 of the reactor. The first porous wall 452 is preferably annular and comprises a first upper plate 454 that seals the upper open end of the first porous wall 452, thereby defining a first closed cavity 456. The other end of the first porous wall 452 is sealed with a first heater 458, the first outlet 461 of the heater communicates with the first closed cavity 456.

 The first reagent gas stream enters the first preheater 458 and then flows into the first closed cavity 456 at a higher pressure than the pressure in the 447 reactor volume. Thus, one side of the first porous wall 452 is exposed to a higher pressure of the reactant gas than the other side of the first porous wall. In the example shown in FIG. 15, the inner side of the porous wall 452 (closed cavity 456) is exposed to a higher pressure of the reactant gas than the outer side of the porous wall 452. The pressure drop causes the first flow of reactant gas to pass through the first porous wall, where the heated gas decomposes and precipitates the binder matrix material in the heated first porous wall 452. After this, the remaining gas and by-products exit the first porous wall 452 and are removed from the reactor volume 447 through exhaust pipes 450 using a vacuum device and 448. Thus, reactant gas is dispersed in the annular porous wall by supplying and exhausting the reactant gas from the furnace for vapor infiltration of chemicals and chemical vapor deposition on opposite sides of the annular porous wall. At least one exhaust pipe 450 is preferably provided between each two porous walls. Each heater 452 can also supply reactant gas to more than one annular porous wall 452. The furnace 400 can be heated by any method known in the art for heating. furnaces for gas phase infiltration of a chemical substance and chemical vapor deposition, moreover, this method can be resistive heating and induction heating.

 According to a preferred embodiment, the heater 458 and the porous wall 452 are heated by radiation from the current collector 462 (induction currents), which surrounds the first heater 458 and the porous wall 452 from all sides. The current collector 462 limits the volume 447 of the reactor and the base 463 on which the first heater 458 rests. The current collector 462 preferably contains an annular part 464, and the furnace 400 contains a first inductor 466, a second inductor 468 and a third inductor 470 that surround the annular part 464. The current collector 462 is connected with inductors 466, 468 and 470, which transfer energy to the current collector, where it is converted into heat by a method known in the art. Maintaining a uniform temperature from the bottom to the top of the furnace to infiltrate the gas phase of the chemical and chemical vapor deposition during the compaction of a large number of porous structures (hundreds) can be difficult. The rate at which the gas decomposes and precipitates the matrix of the binder material is largely determined by the temperature, while the concentration of the reactant gas is sufficient. Thus, deviations in the temperature of the porous structure in the furnace cause corresponding deviations in the increase in bulk density, which can reduce the yield during the implementation of this technological cycle of gas phase infiltration of a chemical substance and chemical vapor deposition. The use of multiple inductors, as shown in FIG. 15 allows a different amount of heat to be applied along the length of the furnace. Thus, a more uniform temperature profile of the porous structure along the furnace (in the direction of gas flow) can be obtained.

 According to another embodiment, the first gas temperature of the first reagent gas stream is measured near the outlet 461 of the first heater using the first temperature sensor 490. The temperature sensor 490 may comprise a type K thermocouple in a suitable protective case. To achieve the desired gas temperature, the heater temperature can be adjusted. It is not necessary to directly measure the temperature of the heater, since the temperature of the heater due to convection is related to the temperature of the gas at the outlet 461. The temperature of the heater is controlled by increasing or decreasing the heating of the first heater 458. As shown in FIG. 15, the current collector wall 464 consists of a first current collector wall part 467, a second current collector wall part 469, and a third current collector wall part 471. The first inductor 466 is connected to the first part 467 of the wall of the current collector so as to convert its electrical energy into thermal energy in the first part 467 of the wall of the current collector. The same applies to the second current collector wall part 469 and the second inductor 468, as well as the third current collector wall part 471 and the third inductor 470. The first heater 458 is heated mainly by the heat energy emitted by the first current collector wall part 467, which is adjacent to the first inductor 466. Thus, the temperature of the first heater can be adjusted by adjusting the electric power supplied to the first inductor 466. The electric power supplied to the second inductor at 468 and 470 to the third inductor may be adjusted to the desired value to maintain a desired temperature profile along the porous structure of the furnace length. The first heater 458 is preferably located near the first part 467 of the wall of the current collector, which improves the transfer of thermal energy by radiation. The temperature measured by the first temperature sensor 490 may be transmitted to the controller 414 via a first measurement data transmission line 494 of the first temperature sensor. The controller can process the measurement data of the temperature sensor and automatically adjust the electrical power supplied to the first inductor 466 as necessary to achieve the desired temperature of the first gas stream when it leaves the outlet 461 of the first heater. In some furnace devices, the heater may be located near the center of the furnace and surrounded by adjacent heaters that are located near the wall of the current collector and the unit for transmitting thermal energy by radiation to the center of the heater. In this case, the central heater is heated mainly by thermal conductivity from adjacent heaters that are heated by radiation. Thus, the central heater is indirectly heated by radiation from the wall of the current collector, and the temperature of the central heater can be adjusted by changing the electric power supplied to the first inductor 466. The heaters can also have resistive heating, which will directly regulate the thermal energy supplied to each heater. Any of these options are possible for use in the present invention.

 The second porous wall 472 can be sealed with a second heater 478 and has a second upper plate 474. The second heater 478 has an inlet 480 and an outlet 481. To measure the temperature of the second reagent gas stream when it exits the outlet of the second heater 481, it can a second temperature sensor 492 will be provided. A second porous wall 472 defines a second closed cavity 476 that communicates with the outlet 481 of the second heater. The second gas stream is supplied to the second heater through the corresponding furnace supply line 408, after which it is scattered through the second porous wall 472 and leaves the furnace volume 446 in the same way as described with respect to the first porous wall 452. Thus, one side of the second porous the walls 472 are subjected to a higher pressure than the other side of the second porous wall 472. According to a particular embodiment, the second heater 478 and the second porous wall 472 heat mainly radiation 464 m from the wall of the susceptor. The second heater 478 is heated to a temperature that is higher than the temperature of the reactant gas from the corresponding furnace feed line 408. The preheated gas is infiltrated through a second porous wall 472, where it decomposes and precipitates a matrix of binder material. After that, the remaining gas and by-products exit the second porous wall 472 and are pulled out of the furnace volume 446 using a vacuum device 448. A second temperature sensor 492 may be located near the outlet 481 of the second heater. The temperature measured by the second temperature sensor 492 may be transmitted to the controller 414 via a measurement data transmission line 496 of the second temperature sensor. The controller 414 can process the temperature sensor measurement data and automatically adjust the electrical power supplied to the first inductor 466 to the desired value to achieve the desired temperature of the second gas stream when it leaves the outlet 481 of the second heater. The electric power supplied to the first inductor 466 can also be manually adjusted to the required value to achieve the desired temperature of the gas stream. At least a third porous wall can be sealed using a similar process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient, wherein in this process at least a third stream of reactant gas is forced to disperse through at least a third porous wall, exposing one side of at least the third porous wall to a higher pressure than the other side, while the third gas flow can be independently adjusted. Similarly, when using additional furnace feed lines 408 and additional heaters, additional porous walls can be added and sealed. Additional heaters and gas flow temperature sensors may be provided near the outlet of each additional heater. Thus, the present invention allows the simultaneous sealing of a large number of porous walls.

 To measure the temperature of the first porous wall 452, a temperature sensor 498 can be provided in close proximity to it. The temperature of the first porous wall can be increased or decreased by increasing or decreasing the flow rate of the first reagent gas stream that passes through the first porous wall 452. For example, the first the reagent gas stream may be at a lower temperature than the porous structure when it exits the outlet 461 of the first heater. An increase in the flow rate of the first reactant gas stream at this lower temperature leads to a decrease in the temperature of the porous wall, and a decrease in the flow rate leads to an increase in the temperature of the porous wall. The opposite phenomenon will occur if the first reagent gas stream has a higher temperature than the first porous wall 452. The temperature sensor 498 of the first porous wall can be connected to the controller 414 by the transmission line 502 of the measurement data of the temperature sensor of the first porous wall, this line allows automatic or manual control of the flow rate of the first gas stream to the required value to achieve the desired temperature of the first porous wall. Similarly, the temperature of the second porous wall can be measured using a temperature sensor 500. The temperature sensor 500 of the second porous wall may be connected to the controller 414 by a data line 504 for measuring the temperature sensor of the second porous wall, this line allowing automatic or manual control of the flow rate of the second gas flow to the required value to achieve the desired temperature of the second porous wall. In a similar way, the temperature of the third and additional porous walls can be measured and adjusted. Each individual gas stream from the furnace feed lines 408 can be independently controlled to influence the process of gas phase infiltration of a chemical substance and chemical vapor deposition by means of a reagent gas supply device 402. The temperature sensors of the porous wall can also be installed directly in the porous walls, as is the temperature sensor 506. A thermocouple can be installed between an adjacent pair of annular porous structures if the porous wall is formed from a packet of porous structures. The temperature of the porous wall can also be measured using an optical pyrometer 548 focused through a window 546 on an optical target 544 located between an adjacent pair of porous walls 452 and 472.

 According to a preferred embodiment, the furnace volume 446 is maintained at a constant vacuum pressure. The pressure inside the first closed cavity 456, the second closed cavity 476, and any third or additional closed cavity is determined by the flow of reagent gas introduced into this cavity and the porosity of the corresponding porous wall. For example, the flow in the first closed cavity 456 may be maintained at a constant volume. At the beginning of the compaction process, the pressure inside the first closed cavity can only be slightly higher than the pressure of the furnace volume outside the closed cavity. The pressure inside the first closed cavity 456 increases as the matrix of binder material is deposited in the first porous wall, since the porosity decreases, and the flow rate of the first reactant gas stream remains constant. The pressure inside the first closed cavity 456 can be controlled by increasing or decreasing the flow rate of the reactant gas in the first closed cavity. An increase in flow increases pressure, and a decrease in flow decreases pressure. To measure the pressure inside the first closed cavity 456, a first pressure sensor 508 may be provided. The first pressure sensor 508 may be connected via line 512 to a controller 414, which allows automatic and manual control of the flow rate supplied to the first closed cavity 456 to the required value to achieve the desired pressure. Similarly, to control the flow rate and pressure inside the second closed cavity 476, a second pressure sensor 510 and a measurement data transmission line 514 by a second pressure sensor may be provided. If necessary, a third and other pressure sensors and transmission lines of measurement data by pressure sensors may be provided. The gas flow rate in this closed cavity is preferably kept constant and the pressure will naturally increase as the porous wall is densified, but it should not increase too quickly and not exceed the maximum specified value, in which case the gas flow rate can be reduced or completely discontinued. The reagent gas supply device 402 allows independent control of the gas flow rate for each porous wall. The current pressure control inside the porous wall also provides an indication of the degree of compaction of each porous wall in real time. A lack of pressure increase or an unusually low pressure increase indicates a leak in the heater and / or in the porous wall. The process can be stopped and subsequently resumed after a leak has been detected and repaired. An unusually rapid increase in pressure may indicate soot formation or gumming of one or more annular porous walls.

 In FIG. 16 shows a heater 100, which is a preferred embodiment of the heaters 458 and 478 shown in FIG. 15. Heater 100 is described in more detail in a pending US patent application entitled “Device for Use with Chemical Phase Gas Infiltration and Gas Deposition Processes” filed on the same day as this application by inventors James W. Rudolph, Mark J. Purdy, and Lowell D. Bock, which is incorporated herein by reference in its entirety. The heater 100 contains a sealed channel structure 102 located in the furnace 10 and resting on the base 463 of the current collector. Gas from the gas inlet 460 (FIG. 15) enters the heater 100, which can be connected to one or more perforated tubes 19, which facilitate the distribution of gas throughout the sealed channel structure 102. The heater 100 comprises a sealed guide structure 108 that rests on the sealed channel structure 102 The sealed guide structure 108 comprises a series of spaced perforated plates 128 and 129 including a lower perforated plate having an inlet channel 104 of the guide structure and an upper perforated A plate having an exhaust channel 106 of the guide structure. The sealed structure 102 and the sealed guide structure 108 are sealed to each other, in addition, the channel structure 102 is sealed with the base 463 of the current collector through the connection 118 so that gas can only flow through the sealed guide structure 108. The sealed channel structure 102 contains at least elements 119 , 120 and 121, the upper ring 122 and the lower ring 123, which together form several tight joints 124, 125, 166, 168, 170, 172 and 174. The support elements 119, 120 and 121 and the lower ring 123 support a sealed guide structure 108. The flat cover 110 preferably abuts the sealed duct device above the perforated plate 106 having outlet openings. The flat cover 110 serves to maintain the retainers of the porous structures and is configured to use a chemical substance and chemical vapor deposition with the gas phase infiltration process under a pressure gradient and has a number of openings 114 and 116, each of which provides a flow of reactant gas to the annular porous the wall. The flat cover 110 is sealed with a sealed channel structure 102 by means of an elastic gasket mounted in connection between them. The perforated plates 128 and 129 are adjacent and located in a block bounded by the perimeter 132 of the guide structure. Each plate 128 of the sealed guide structure has a set of perforations 130, and the perforations 130 of one plate 128 of the current collector are not aligned with the perforations 130 of the adjacent plate 129 of the current collector. Such a device greatly facilitates the transfer of heat by radiation from the wall 464 of the current collector to the directly perforated plates 128 and 129. Along the plates 128 and 129, heat is transferred due to thermal conductivity, and to the gas by forced convection. Around the perimeter 132, the guide structure is sealed by elastic gaskets 134, and the outer border of each plate 128 and 129 is located in close proximity to the wall 464 of the current collector. Gaskets 134 also serve to span perforated plates 128 and 129 relative to each other. The sealed channel structure 102 preferably has a step 136, on which the specified sealed guide structure 108 rests. In the embodiment shown, the support elements 119, 120 and 121 define the step in combination with the lower ring 123. Stands 140 may be provided that reduce the load on the guide the structure 108 in the furnace, and also additionally support the structure 108 and the flat cover 110. Each rack 140 has a larger part (not shown) that rests on the base 463 of the current collector. The sealed guide structure 108 rests on a support. The various elements of the heater 100 are preferably made of monolithic graphite. Various compacted joints are preferably formed using elastic gaskets and / or graphite cement. Suitable pliable gaskets can be made of elastic graphite, for example, flexible sheet graphite of the EGC Thermafoil family, and tape sealants supplied from EGC Enterprises Incorporated, Mentor, Cleveland, Ohio, USA. Compatible materials may be sourced from UCAR Carbon Company Inc., Clevelend, Ohio, USA.

 Porous walls 452 and 472 shown in FIG. 15 may be formed from stacks of annular porous structures that are particularly preferred for the manufacture of aircraft brake discs. In FIG. 17 shows a preferred retainer 200 for sealing a stack of annular porous structures 22 using a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient. The latch 200 is described in more detail in a pending US patent application entitled “Device for use with chemical gas vapor deposition and gas vapor deposition processes” filed on the same day as this application by inventors James B Rudolph, Mark J. Purdy, and Lowell D. Bock. The latch 200 is preferably used with the heater 100 shown in FIG. 16. The porous structures 22 are assembled into a bag 202. The retainer comprises a base plate 204, a spacer structure 206 and an upper plate 208. The upper plate 208 may have an opening 210 that is sealed with a flat cover 212, an elastic gasket 213 and a weight of 214. The base plate 204 is made with can be connected to the flat cover 110 and has an opening (key 216 in FIG. 18) that is aligned with one of the openings 114 or 116 of the flat cover. The base plate 204 is preferably precisely mounted using tapered pins 226. Such a device facilitates alignment of the opening of the base plate with the corresponding hole of the flat cover. The base plate 204 is preferably sealed with a flat cap 110 by means of an elastic gasket.

 The upper plate 208 is located at a distance from the base plate 204. The spacer structure 206 is installed between the base plate 204 and the upper plate 208 and is in contact with them. In the present embodiment, the spacer structure comprises spacer posts 218 located around a pack of porous structures and extending between the base plate 204 and the top plate 208. Each post 218 has pins 220 at each end that are mounted in mating holes 224 in the base plate 204 and the top plate 208. The spacer structure 206 preferably comprises at least three legs 218 and can be made as one element, with other devices for connecting the base plate 204 and top s plate 208, which can be used in the present invention. At least one ring-shaped gasket 234 in outer diameter is located in the bag 202 of porous structures 22 between each pair of neighboring porous structures 22. An annular gasket 234 surrounds the openings 23 of the neighboring porous structures. At least one of the annular gaskets 234 in outer diameter is preferably located between the base plate 204 and adjacent porous structure 22 and between the upper plate 208 and adjacent porous structure 22. Base plate 204, package of porous structures 202 and at least one ring-shaped gasket 234 limit the closed cavity 236 extending from the opening of the base plate (position 216 in FIG. 18), each having an opening 23 of the porous structure and ending near the upper plate 208. As defined in with an embodiment, the outer diameter of the annular gasket 234 is approximately 21.9 inches (556.26 mm) and the inner diameter of the gasket is 19.9 inches (505.46 mm) to obtain annular porous structures 22 having an outer diameter of approximately 21 inches (533 , 4 mm). The annular gaskets preferably have a thickness of at least 0.25 inches (6.35 mm).

 In FIG. 18 shows a preferred retainer 201 for simultaneously sealing a large number of porous structures 22 by a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient. The spacer structure 207 comprises at least one intermediate plate 272 located between the base plate 204 and the upper plate 208, which separates the package of porous structures 203. Racks 218 extend between the upper plate 208 and one of the intermediate plates 272, between the base plate 204 and the other intermediate the plate 272 and between adjacent pairs of intermediate plates 272. In another respect, the retainer 201 is essentially identical to the retainer 200. Each intermediate plate 272 has an opening 274 located between a pair of porous structures round 22. The closed cavity 236 further comprises an opening 274 of each intermediate plate. At least one of the annular gaskets 234 is located on each side and seals the intermediate plate 272 and the porous structures 22. The clips 201 can be assembled into a bag. In this case, the base plate of one retainer 201 is in contact with the upper plate 208 of the lower retainer 201, the opening 216 of the base plate of the upper retainer communicates with the hole 210 of the upper retainer lower plate. Thus, the closed cavity extends from one retainer 201 to the next until it ends with a flat cover 212 located over the opening 210 of the uppermost plate. As can be seen from this drawing, the base plate 204 is provided with conical holes 230 in which the conical part of the conical pins 226 is mounted, and a flat cover 110 is provided with the holes 228 in which the cylindrical part of the conical pins 226 is mounted.

 In FIG. 28 depicts an alternative retainer 299 for densifying a pack of porous structures under a pressure gradient. The latch 299 is essentially identical to the latch 200 except that the bag 302 contains annular gaskets 234 located on the outer diameter of each porous structure 22, alternating with annular gaskets 284 located on the inner diameter of each porous structure. O-rings 234 in outer diameter preferably have an inner diameter 233 slightly smaller than the outer diameter 608 of the porous structure. O-rings 284 in inner diameter preferably have an outer diameter of 286 slightly larger than the inner diameter of the porous structure 610, and an inner diameter of 288, which generally coincides with the inner diameter of the porous structure 610. With ring-shaped gaskets 284, the outer diameter of the porous structure 608 is larger than the outer diameter 286 of the ring-shaped gasket 284. The wall thickness of each ring-shaped gasket 234 and 284 is preferably minimized in order to maximize the impact on the surface area of the porous structure of the reactant gas as it enters or leaves each porous structure 22. In FIG. Figure 29 shows an alternative retainer 301 for sealing under a pressure gradient of the packet of porous structures 303. The retainer 301 is substantially identical to the retainer 200 except that all of the ring-shaped gaskets of the bag 303 are ring-shaped gaskets 284 in inner diameter located along the inner diameter of each porous structure.

 The various elements of the retainers 200, 201, 299 and 301 are preferably made of graphite. The various joints formed in the retainers are preferably sealed by O-rings configured to compress from a flexible graphite material, as described above. If the porous structures 22 are compressible, they can be pressed directly to the annular gaskets 234 to provide sufficient sealing and elimination of seals between the porous structures 22 and the annular gaskets 234. The ring-shaped gaskets are preferably coated with a sealant having a pyrolytic carbon deposition surface, which facilitates removal of the annular gasket from the compacted porous structure after deposition of a matrix of a binder material.

 Clamps, similar to clamps 200 and 201, can be used in the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition, in which the annular gaskets 234 are replaced by spacer blocks that separate porous structures and allow the reactant gas to freely pass through, on top of and around the porous structures 22. In this case, the flat cover 110 may be replaced by the flat cover 152 shown in FIG. 22, in order to facilitate the distribution of the reactant gas over the furnace volume. Flat cover 152 contains a set of holes 153. Seals of various compounds formed in the retainer, made with the possibility of using a chemical substance and chemical vapor deposition in the standard process of gas phase infiltration, are not necessary or desirable.

In FIG. 19 is a schematic diagram of a method for gas phase infiltration of a chemical substance and chemical vapor deposition according to an aspect of the present invention. According to a preferred embodiment, a large number of annular porous carbon structures are placed in a furnace for gas phase infiltration of a chemical substance and chemical vapor deposition, for example in a furnace 400 (FIG. 15), using group fixatives, for example fixative 201 (FIG. 18) which is sealed to group heaters, for example, to heater 100. Reagent gas is supplied to the furnace using a device such as a gas supply device 402 (FIG. 15). The furnace is heated until conditions are stabilized, after which the first carbon matrix is deposited in porous structures using the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient. Greater support for porous structures than shown in FIG. 17 and 18, during the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, it is not necessary since porous structures do not sag during this process. Then the porous structures are subjected to heat treatment without removing them from the furnace or from the retainers. Alternatively, the porous structures may be removed from the furnace and retainers before performing heat treatment. The heat treatment is carried out at a higher temperature than the temperature of the deposition process described above, which increases the graphitization of the first carbon matrix. After heat treatment, the porous structures are removed from the furnace and subjected to mechanical surface treatment to ensure accurate measurement of bulk porosity. Surface machining can also increase open porosity on the surface. After that, in the porous structures using the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition from the gas phase, a second carbon matrix is deposited. Thus, the second matrix overlaps the first matrix. After reaching the final density, the densified structures are machined to obtain the final parts. In a specific embodiment, the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient and the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition were carried out at a temperature of about 1750-1900 ^° F (954.4-1037.8 ^o C), and heat treatment was carried out at a temperature of approximately 3300-4000 ^o F (1815-2260.0 ^o C). Thus, the first matrix has a higher level of graphitization due to the intermediate heat treatment process.

 In FIG. 20 is a schematic diagram of an alternative method that begins with a gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient by which a first carbon matrix is deposited in porous structures. Then, the porous structures are heat treated without removing the porous structures from the furnace or from the retainers. After that, during another process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient that immediately follows the heat treatment process, a second carbon matrix is deposited. Alternatively, the porous structures may be removed from the furnace and retainers prior to the heat treatment process and returned to retainers to infiltrate the gas phase of the chemical and chemical vapor deposition at the pressure gradient before the second such process. Then the porous structures are subjected to surface machining. After that, using the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition, an additional second carbon matrix is deposited and the porous structures are machined to obtain the final parts. Leaving porous structures in the same furnaces and fixers during the first and second processes of gas phase infiltration of a chemical substance and chemical deposition from a gas phase under a pressure gradient and heat treatment process provides a “continuous” method. To prevent subsidence during the heat treatment process, additional support blocks may be required located between adjacent pairs of porous structures in the retainers.

 In FIG. 21 shows an alternative schematic diagram of a method that begins with a gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient in which a first carbon matrix is deposited in porous structures. The porous structures are subjected to surface machining and then, using the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition from a gas phase, a second carbon matrix is deposited at a pressure gradient, followed by heat treatment.

 After heat treatment, the completely compacted porous structures are machined to obtain the final parts. Obviously, the process sequences shown in FIG. 19 to 21, additional operations may be modified and introduced without departing from the spirit and scope of the present invention.

The first and second carbon matrices preferably have a substantially coarse layered microstructure. The coarse layered microstructure has a higher density (approximately 2.1 g / cm ³ ), higher thermal conductivity and lower hardness than a uniform layered microstructure. A coarse layered microstructure is particularly preferred for some carbon / carbon aviation brake discs. The microstructure can be optically characterized as described by M.L. Lieberman and H.O. Pearson in the work “Effect of gas phase parameters on pyrocarbons of the obtained matrix in carbon / carbon composite materials”, 12 Carbon 233-41 (1974).

 In FIG. 23 illustrates a compacted porous structure 600 obtained in accordance with any method shown in FIG. 19, 20 or 21. The densified porous structure 600 has a first annular zone 612 adjacent to the inner annular surface 82 and a second annular zone 614 adjacent to the outer annular surface 84. The first and second annular zones 612 and 614 extend over the entire thickness of the densified porous structure 600 and connected by opposite surfaces 78 and 80. The densified porous structure 600 contains a first carbon matrix deposited in a porous structure consisting of carbon fibers and obtained during the process of gas phase chemical vapor infiltration society and chemical deposition from the gas phase pressure gradient. According to a preferred embodiment, the first carbon matrix is deposited by a process in which retainers 200 and / or 201 are used having annular outer pads 234 (FIGS. 17 and 18), which is similar to the process described with reference to FIG. 5, and leads to uneven deposition of the first carbon matrix providing a density distribution similar to that found in the densified porous structure 330 shown in FIG. 11. The first annular zone 612 is subjected to a higher pressure of the reactant gas than the second annular zone 614 during the compaction process by infiltration of the gas phase of the chemical and chemical vapor deposition at the pressure gradient, which leads to the first annular zone 612 has a higher density increase than the second annular zone 614. In a particular embodiment, the second annular zone 614 has about 15% less than the first carbon matrix per unit less than the first annular zone 612, and the first carbon matrix preferably has a substantially coarse layered microstructure. The second annular zone 614, as a rule, has at least 10% less than the first carbon matrix per unit volume than the first annular zone 612, and may have less than the first carbon matrix by 20%, 30%, 40% and further%. The densified porous structure 600 also contains a second carbon matrix deposited using a standard gas phase infiltration process and chemical vapor deposition on the first carbon matrix, resulting in a densified porous structure 600 having a final density distribution that is the same as that in the densified the porous structure 340 shown in FIG. 12. The second carbon matrix also preferably has a substantially coarse layered microstructure. The first and second carbon matrices preferably have at least 90% coarse layered microstructure, more preferably at least 95% coarse layered microstructure, and in some preferred embodiments, 100% coarse layered microstructure.

 The first carbon matrix can be subjected to heat treatment, which leads to the fact that it becomes more graphitized than the second carbon matrix. An increase in graphitization increases bulk density and thermal conductivity. Thus, the initial density gradient after the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient can be identified in the densified porous structure 600 after deposition of the second carbon matrix. If the first carbon matrix has such a distribution as shown in FIG. 11, the first annular zone 612 has, as a rule, higher thermal conductivity than the second annular zone 614, and, as a rule, a higher bulk density than the second annular zone 614, even after deposition of the second carbon matrix. Closed porosity remaining in the densified porous structure 600 affects the measurement of bulk porosity. The effects of porosity can be minimized by measuring the bulk density of the crushed samples, referred to in this application as the bulk density of the crushed samples. In accordance with a specific methodology, the bulk density of the crushed samples was measured by cutting a sample from a compacted porous structure and destroying the sample between parallel steel plates of the ultimate load test. The sample is preferably destroyed so as to preserve it in one piece. This can be done by compressing the sample beyond the yield strength without crushing. After this, bulk density was measured in accordance with the Archimedes method using white spirit, for example Isopar M (synthetic isoparaffin hydrocarbon), supplied from Exxon Chemical Americas, Houston, Texas, USA. Vacuum was used to force the introduction of white spirits into this structure. Bulk density is determined by measuring the density of a material that is not permeable to penetration by white spirits. The destruction of the sample reveals previously closed porosity, which was impervious to the penetration of white spirits and minimizes the effects of porosity. Alternatively, the bulk density of the crushed crushed samples can be measured using a helium pycnometer. Density measurements of densified porous structures obtained similarly to densified porous structure 600 showed that the bulk density of the crushed samples adjacent to the inner annular surface 82 was respectively at least 0.2% higher, and maybe 0.4 and 0, 5% more than adjacent outer circumferential surface 84. Thus, the bulk density of the crushed samples tends to decrease in the direction from the inner surface 82 to the outer surface 84.

The thermal conductivity of densified porous structures similar to those of densified porous structure 600 (as described in the previous paragraph) was measured in two directions: perpendicular to opposite surfaces 78 and 80, which will be referred to as
"thermal conductivity of the plane", and perpendicular to the annular surfaces 82 and 84 (in the radial direction), which will be referred to as "thermal conductivity of the edge". The thermal conductivity of the plane of the annular zone 614 was at least 5% less than the annular zone 612, when measured on opposite surfaces 78 and 80. The thermal conductivity of the plane of the annular zone 614 was at least 12% less than the annular zone 612 half the distance between opposite surfaces 78 and 80. The thermal conductivity of the edge of the annular zone 614 was at least 5% less than the annular zone 612, when measured on the opposite surfaces 78 and 80. The thermal conductivity of the edge of the annular zone 614 was at least 4% less than annular zone 612, when measured at half the distance between opposite surfaces 78 and 80. Thus, thermal conductivity tends to decrease from the inner annular zone 612 to the outer annular zone 614. This tendency is explained by higher graphitization of the first matrix than the second.

 The following examples further illustrate various aspects of the present invention.

EXAMPLE 1
The following was established for the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. A fibrous textile structure with a thickness of approximately 1.5 inches (38.1 mm) was obtained in accordance with FIG. 1-4, US Pat. No. 4,790,052, starting with a 320K unidirectional polyacrylonitrile fiber tow. Thereafter, an annular porous structure having an outer diameter of about 7.5 inches (190.5 mm) and an inner diameter of about 2.5 inches (63.5 mm) was cut from the textile structure. The annular porous structure was then pyrolyzed to convert the fibers to carbon. Thereafter, a pyrolyzed porous structure having a bulk density of 0.49 g / cm ³ was placed in a furnace similar to furnace 11 shown in FIG. 14. The pressure inside the furnace was reduced to 10 millimeters of mercury and the furnace was heated and stabilized at a temperature of approximately 1860 ^° F (1015.6 ^° C), measured with a temperature sensor located as temperature sensor 76 shown in FIG. 14. The reagent gas mixture was introduced as described in FIG. 14, where it is freely scattered through and around the porous structure as in the usual standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. The reagent gas mixture contained 87 vol.% Natural gas and 13 vol.% Propane at a flow rate of 4000 cm ³ / min and a residence time of approximately 1 second in the reactor volume. Natural gas had a content of 96.4 vol.% Methane, 1.8 vol.% Ethane, 0.50 vol. % propane, 0.15 vol.% butane, 0.05 vol.% pentane, 0.70 vol.% carbon dioxide and 0.40 vol.% nitrogen. The process was stopped three times to measure the increase in bulk porosity. The total deposition process time was 306 hours. For each of the three compaction cycles, the average deposition rate was calculated. Table 1 shows the test conditions and data taken from this example, including the total deposition time and the total increase in density for each specified cumulative time. Almost the entire carbon matrix deposited in the compacted porous structure had a coarse layered microstructure at the end of the process with minimal deposition of an even layered microstructure on the surface of the porous structure.

EXAMPLE 2
An annular porous structure having a thickness of 1.6 inches (40.64 mm), an outer diameter of 6.2 inches (157.48 mm) and an inner diameter of 1.4 inches (35.56 mm) was cut from a fibrous textile structure and subjected technological processing, as in example 1, using the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. Table 2 shows the test conditions and data taken from this example.

EXAMPLE 3
Two ring-shaped porous structures (discs A and B) obtained from a fibrous textile structure and having the same dimensions as in Example 1 were compacted using a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient using a furnace, similar to the furnace 10 shown in FIG. 1, a latch similar to the latch 2 shown in FIG. 2, having ring-shaped gaskets on the inner and outer diameters, and the reagent gas mixture of Example 1. The test conditions and data taken from this example are shown in Table 3. The furnace pressure was 10 millimeters of mercury. The temperature of the gas stream measured with a temperature sensor, for example a temperature sensor 74, shown in FIG. 1 was 1740 ^° F (948.9 ^° C). Gas flowed through the porous structure as described above with reference to FIG. 2, at a flow rate of 4000 cm ³ / min. The entire carbon matrix deposited in disk A had a coarse layered structure. The microstructure of disc B was not determined. Disk A was cut into small samples and the bulk density of these samples was measured by the Archimedes method, and the resulting density profile was similar to that shown in FIG. 8.

EXAMPLE 4
Three ring-shaped porous structures (discs A, B, and C) were obtained and separately densified by a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient in the same manner as in Example 3, except that the porous structures were turned over during the process in order to obtain a more uniform distribution of the final density. The temperature of the gas stream measured with a temperature sensor, for example a temperature sensor 74 shown in FIG. 1 was 1740 ^° F (948.9 ^° C). Test conditions and data taken from this example are shown in table 4.

EXAMPLE 5
Two annular porous structures obtained from a fibrous textile structure and having the same dimensions as in Example 1 were simultaneously densified by a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient using a clamp similar to retainer 6 shown in FIG. 4, having all the ring-shaped gaskets in inner diameter, and the reagent gas mixture of Example 1. The temperature of the gas stream measured with a temperature sensor, for example, temperature sensor 74 shown in FIG. 1 was 1745 ^° F (951.6 ^° C). The test conditions and data taken from this example are shown in Table 5. The density increase data shown in Table 5 is the arithmetic average of two disks. The entire carbon matrix deposited in the densified porous structure had a coarse layered structure at the end of the process. Computed tomographic scanning of the disks yielded density profiles similar to those shown in FIG. 10.

EXAMPLE 6
Four ring-shaped porous structures obtained from a fibrous textile structure and having the same dimensions as in Example 1 were densified by a gas phase infiltration process of a chemical substance and chemical vapor deposition using a pressure gradient using a retainer similar to retainer 8 shown in FIG. 5 having all ring-shaped gaskets in outer diameter and the reagent gas mixture of Example 1. Two disks were sealed simultaneously (disk pair A and B) and the reagent gas flow rate was doubled to maintain a flow rate of 4000 cm ³ / min on the disk . The temperature of the gas stream measured with a temperature sensor, for example a temperature sensor 74, shown in FIG. 1 was approximately 1750 ^° F (954.4 ^° C). The test conditions and data taken from this example are shown in Table 6. The density increase data shown in Table 6 is the arithmetic mean for each pair of disks. The entire carbon matrix deposited in the densified porous structure had a coarse layered structure at the end of the process. The tomographic scan calculations of disk pair B yielded density profiles similar to those shown in FIG. eleven.

EXAMPLE 7
An annular porous structure was obtained from a fibrous textile structure having the same dimensions as in Example 2, and was densified by a gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient using a clamp similar to retainer 7 shown in FIG. . 7 having all the ring-shaped gaskets in inner diameter, which provided a reverse flow of the reagent gas, and the mixture of the reagent gas from Example 1. The temperature of the gas stream, measured using a temperature sensor, for example temperature sensor 74, shown in FIG. 1 was 1730 ^° F (943.3 ^° C). The reactant gas flowed through the porous structure as described above with reference to FIG. 7, with a flow rate of 3000 cm ³ / min (flow rate was reduced because the disk was smaller than the disks used in examples 3-6). The test conditions and data taken from this example are shown in Table 7. The carbon matrix deposited in the densified porous structure had a substantially uniform layered microstructure at the end of the process.

In FIG. 24 in the form of graphs presents the data shown in tables 1-7. The data taken from tables 1 and 2 are represented by a single smooth curve 516 representing the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. The data taken from tables 3 and 4 are represented by a single smooth curve 518, representing the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient using ring-shaped gaskets along the inner and outer diameters. The data taken from Table 5 is represented by a single smooth curve 520 representing the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient using only ring-shaped gaskets with an inner diameter. The data taken from table 6, is presented by one smooth curve 522, representing the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient using only ring-shaped gaskets in outer diameter. The data taken from Table 7 is represented by a single smooth curve 524, representing the process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient with a reverse flow of reagent gas and using only ring-shaped gaskets with an inner diameter. Compaction rates increased 0.5-5 times compared to compaction rates using the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. The time required to increase the bulk density by 1 g / cm ³ decreased by approximately 25-80% compared with the time required by using the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. The importance of avoiding leaks as much as possible is apparent from FIG. 24. Any leakage will reduce the compaction speed from the maximum achievable value. Increased compaction rates can be achieved even with a small leak. Thus, some leakage may occur according to the present invention.

In FIG. 25 shows curves of the compaction rate versus normalized flow. The normalized flow is denoted by F ^* and represents the value of the flow per unit volume of the disk (for example, 4000 cm ³ / min per disk volume 1000 cm ³ = 4 min ^-1 ). Additional tests were carried out in accordance with the above examples 6 and 7 except that the flow rate of the reactant gas was changed from test to test. The data obtained from the tests carried out in accordance with Example 6 with a variable flow are shown in Table 8, and the data taken from the tests carried out in accordance with Example 6 with a variable flow are shown in Table 9. Curve 526 represents the standard gas infiltration process. chemical phase and chemical vapor deposition. The data taken from table 8, is represented by curve 528, which represents the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient using all ring-shaped gaskets along the outer diameter (Fig. 5). The data taken from table 9, is presented by curve 530, which represents the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient using all ring-shaped gaskets in inner diameter (Fig. 7).

 In FIG. Figure 26 shows curves representing the dependences of compaction rate on normalized flow. Additional tests were carried out in accordance with example 6 described above (the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient using all ring-shaped gaskets with an outer diameter, except that the pressure in the furnace volume and the gas flow rate the reagent was changed from test to test.The data obtained from these tests are shown in table 10. The data taken from table 10 are represented by three curves 532, 534 and 536. Curve 532 represents the data at a pressure in the furnace volume of 10 millimeters of mercury, curve 534 presents data at a pressure in the furnace volume of 25 millimeters of mercury, curve 536 represents data at a pressure in the kiln volume of 50 millimeters of mercury. pressure 72 shown in Fig. 1. The entire matrix deposited in all of these tests has a coarse layered microstructure. 26, additional increases in compaction speed while maintaining the desired coarse layered microstructure can be obtained by increasing the pressure in the furnace volume (pressure in the reactor). This was an unexpected discovery.

In FIG. Figure 27 shows the pressure drop across the porous structure versus bulk density for several flow rates of the reactant gas. Additional tests were carried out in accordance with example 6 at different flow rates. The data obtained from these tests are shown in table 11. The data taken from table 11 are shown in FIG. 27, the first set of curves 538 obtained for a flow rate of 1000 cm ³ / min per disk, the second set of curves 540 obtained for a flow rate of 2000 cm ³ / min per disk, and the third set of curves 542 obtained for a flow rate of 4000 cm ³ / min to disk. The entire matrix deposited in all of these tests had a coarse layered microstructure. Table 11 shows the initial pressure drop across the porous structure and the final pressure drop across the porous structure, with the pressure in the reactor volume being kept constant. As follows from FIG. 27, the pressure gradient across the porous structure may be at least 80 millimeters of mercury (which indicates a pressure of 90 millimeters of mercury on the side of the porous structure that has a higher pressure) while maintaining the desired coarse layered microstructure.

Tests have shown that the process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient corresponding to the present invention can be carried out at a temperature of the part in the range of 1800-2000 ^° F, a pressure in the reactor in the range of 10-150 millimeters of mercury, normalized flow rate (F ^* ) in the range of 0.4-10 min ^-1 and a mixture of hydrocarbon reagent gas, which is a mixture of natural gas and 0-40 vol.% propane. Carrying out the process in these ranges allows you to get a rough layered and / or smooth layered microstructure. Carrying out this process with all technological parameters selected at or near the upper limit of each of these ranges can lead to gumming or soot formation. Without departing from the spirit and scope of the present invention, other carbon-containing gases, pressures, and temperatures known from the prior art for use in chemical gas deposition and gas vapor deposition processes can be used in the processes.

The compaction of the porous structure by a gas phase infiltration process of a chemical substance and chemical vapor deposition under a pressure gradient in accordance with the present invention, followed by the standard process of gas phase infiltration of a chemical substance and chemical vapor deposition, gives a densified porous structure having more uniform density distribution than that of a porous structure densified only by the standard chemical gas phase infiltration process eschestva and chemical vapor deposition. According to a particular embodiment, for example, an annular porous carbon structure having an inner diameter of about 10.5 inches (266.7 mm) (indicated in FIG. 23, position 602), a wall (indicated in FIG. 23, position 604) a thickness of approximately 5.25 inches (133.35 mm) and having a thickness (indicated in FIG. 23, item 606) of approximately 1.25 inches (31.75 mm), was first compacted with a carbon matrix deposited by a chemical gas phase infiltration process substance and chemical vapor deposition at a pressure gradient (conditions I, of example 6), using a clamp, for example clamp 201 (FIG. 18), in a furnace, for example in a furnace 400 (FIG. 15), which gave a density distribution similar to the density distribution of the densified structure 330 shown in FIG. 11. The carbon matrix, further precipitated using a standard chemical gas infiltration and gas vapor deposition process (conditions of Example 1), resulted in a density distribution similar to the density distribution of the densified structure 340 shown in FIG. 12, and had an average bulk density of approximately 1.77 g / cm ³ . The standard (quadratic) bulk density deviation for the densified structure was approximately 0.06 g / cm ³ . The standard deviation of the bulk density of a comparable porous carbon structure, compacted to an equivalent average bulk density using only standard processes of gas phase infiltration of a chemical substance and chemical vapor deposition, was approximately 0.09 g / cm ³ . Thus, a porous structure densified by a gas phase infiltration process of a chemical substance and chemical vapor deposition at a pressure gradient followed by a standard process of chemical gas infiltration and chemical vapor deposition has a more uniform density distribution than a porous structure densified only by standard processes of gas phase infiltration of a chemical substance and chemical vapor deposition. Both peripheral and general deviation are reduced. Uniformity is desirable for carbon / carbon aviation brake discs.

The standard deviation of the bulk density in the carbon / carbon structure obtained in accordance with the present invention is preferably less than or equal to 0.07 g / cm ³ and more preferably less than or equal to 0.06 g / cm ³ or 0.05 g / cm ³ , and most preferably, less than or equal to 0.04 g / cm ³ or 0.03 g / cm ³ . The deviation coefficient of bulk density in any compacted porous structure is preferably less than or equal to 4%, more preferably less than or equal to 3.5% or 3%, and most preferably less than or equal to 2.3% or 1.8%.

 Obviously, without deviating from the scope of the present invention defined in the claims, many changes are possible.

Claims (77)

 1. The method of gas phase infiltration of a chemical substance and chemical vapor deposition, comprising partially densifying a porous structure in a furnace by gas phase infiltration of a chemical substance and chemical vapor deposition by deposition of one matrix in a porous structure, characterized in that the gas infiltration process is carried out phase of a chemical substance and chemical vapor deposition at a pressure gradient at which the first part of the specified porous structure is exposed higher pressure than the second part of the porous structure, wherein said first part has a higher bulk density increment than the second part, as well as the subsequent densification of said porous structure by deposition of another matrix in said porous structure by at least one additional a compaction process in which said second part has a higher bulk density increment than said first part.  2. The method according to claim 1, characterized in that the additional sealing process is a standard process of gas phase infiltration of a chemical substance and chemical vapor deposition.  3. The method according to claim 1. characterized in that said additional densification process is a process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient, said second part being subjected to a higher pressure than said first part.  4. The method according to claim 1, characterized in that said additional compaction process is a resin impregnation process comprising charring said resin.  5. The method according to claim 1, characterized in that before the subsequent subsequent compaction of the porous structure by means of at least one additional compaction process, heat treatment of said partially densified porous structure is carried out at a higher temperature than the temperature of said process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient.  6. The method according to p. 1, characterized in that said porous structure is a carbon porous structure, and in said process of gas phase infiltration of a chemical substance and chemical vapor deposition from a gas phase, a carbon matrix is deposited in said porous structure under a pressure gradient.  7. The method according to p. 1, characterized in that said porous structure is ring-shaped and has two, as a rule, flat opposite surfaces, wherein said first part includes one of these opposite surfaces, and said second part includes another of these two opposite surfaces.  8. The method according to p. 1, characterized in that said porous structure is ring-shaped and has an inner annular surface and an outer annular surface, wherein said first part includes said inner annular surface, and said second part includes said outer annular surface.  9. The method according to p. 1, characterized in that said porous structure is ring-shaped and has an inner annular surface and an outer annular surface, wherein said first part includes said outer annular surface, and said second part includes said inner annular surface.  10. The method according to claim 1, characterized in that said porous structure is ring-shaped and has two, as a rule, parallel flat surfaces connected by an inner annular surface and an outer annular surface spaced from the surrounding inner annular surface and surrounding it, said first part includes said inner annular surface and one of said two parallel planar surfaces, and said second part includes said outer annular overhnost and the other of said two parallel flat surfaces.  11. The method according to claim 1, characterized in that said porous structure is ring-shaped and has two parallel flat surfaces connected by an inner annular surface and an outer annular surface spaced from and surrounding the said inner annular surface, wherein said first part includes the specified outer surface and one of these two parallel flat surfaces, and the specified second part includes the specified inner annular surface and the other of these two parallel flat surfaces.  12. The method according to claim 1, characterized in that after said process of gas phase infiltration of a chemical substance and chemical vapor deposition under a pressure gradient and before said subsequent densification of said porous structure, said porous structure is thermally treated at a higher temperature than temperature the specified process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient.  13. The method according to claim 1, characterized in that after said process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, said porous structure is heat treated without having to be removed from said furnace.  14. The method according to claim 1, characterized in that said porous structure is a series of annular fibrous carbon structures.  15. The method according to claim 1, characterized in that each annular fibrous carbon structure has two flat parallel surfaces, wherein said first part includes one of said two parallel surfaces, and said second part includes the other of said two, generally parallel surfaces.  16. The method according to claim 1, characterized in that each annular fibrous carbon structure has an inner annular surface and an outer annular surface, wherein said first part includes said inner annular surface, and said second part includes said outer annular surface .  17. The method according to claim 1, characterized in that each annular fibrous carbon structure has an inner annular surface and an outer annular surface, wherein said first part includes said outer annular surface, and said second part includes said inner annular surface .  18. The method according to 14, characterized in that each annular fibrous carbon structure has two parallel flat surfaces connected by an inner annular surface and an outer annular surface spaced from the surrounding inner annular surface and the first part includes the specified inner annular surface and one of these two parallel flat surfaces, and the specified second part includes the specified outer annular surface and the other of these two parallel flat surfaces.  19. The method according to 14, characterized in that each annular fibrous carbon structure has two parallel flat surfaces connected by an inner annular surface and an outer annular surface spaced from the surrounding inner annular surface and the first part includes the specified outer annular surface and one of these two parallel flat surfaces, and the specified second part includes the specified inner annular surface and the other of these two parallel flat surfaces.  20. The method according to 14, characterized in that after the specified process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient and before said subsequent densification of said annular fibrous structure, heat treatment of said annular fibrous structure is carried out at a higher temperature, than the temperature of the indicated process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient.  21. The method according to p. 20, characterized in that after said process of gas phase infiltration of a chemical substance and chemical vapor deposition at a pressure gradient, said porous structure is heat treated without having to be removed from said furnace. 22. The method according to PP.1 to 21, characterized in that the heating of the porous carbon structure, at least to a temperature of 954.4 ^o C (1750 ^o F) and heating of the hydrocarbon gas reagent, at least to a temperature of 899 ^o C (1650 ^o F), and a partial seal of the specified porous carbon structure is carried out to ensure the passage of the specified reagent gas through the specified porous carbon structure from the first part to its second part, in which the specified first part has a higher increment in bulk density than specified second part While also conducted subsequent sealing of said porous carbon structure by depositing a second matrix in said porous carbon structure by means of at least one additional densification process in which said second portion has a higher bulk density increment than said first portion.  23. The method according to item 22, wherein said second matrix is a carbon matrix, and said additional densification process is a standard process of gas phase infiltration of a chemical substance and chemical vapor deposition. 24. The method according to item 22, wherein said additional densification process includes heating the porous carbon structure to at least 954.4 ^o C (1750 ^o F), heating the hydrocarbon reactant gas, at least , to a temperature of 899 ^o C (1650 ^o F) and the supply of the specified reagent gas around the specified porous structure. 25. The method according to item 22, wherein after partial densification of the specified porous carbon structure and before the subsequent subsequent densification, additional heat treatment of the specified porous carbon structure is carried out, at least at a temperature of 1815 ^o C (3300 ^o F).  26. The method according A.25, characterized in that the heat treatment of the specified porous structure is carried out after the specified process of gas phase infiltration of the chemical substance and chemical deposition from the gas phase at a pressure gradient without removing the specified porous carbon structure from the specified furnace.  27. The product obtained using the method according to claims 1 to 26.  28. A friction disk containing a compacted annular porous structure having a first carbon matrix deposited thereon, characterized in that said porous structure includes a second carbon matrix deposited on an annular porous structure on top of said first carbon matrix, and has two, typically parallel flat surfaces connected by an inner annular surface and an outer annular surface spaced from the inner annular surface and surrounding it, wherein the first the annular part of the porous structure is adjacent to the indicated inner annular surface, and its second annular part is adjacent to the indicated outer annular surface, wherein said first and second annular parts are connected by the indicated two parallel flat surfaces, and said second annular part contains at least 10% less than said first carbon matrix per unit volume than said first annular portion, said first and second carbon matrices having a substantially coarse layered micro structure, and said first carbon matrix is more graphitized than said second carbon matrix.  29. The friction disc of claim 28, wherein said first and second carbon matrices have at least 90% coarse layered microstructure.  30. The friction disk according to claim 28, wherein said first annular part has a higher thermal conductivity in the direction perpendicular to said two parallel flat surfaces than said second annular part.  31. The friction disk according to claim 28, wherein said first annular part has higher thermal conductivity in a direction perpendicular to said first and second annular surfaces than said second annular part.  32. The friction disk according to claim 28, wherein said first annular part has a higher bulk density of crushed samples than said second annular part.  33. The friction disk according to claim 28, wherein said first annular part has a 0.2% higher bulk density of crushed samples than said second annular part.  34. The friction disk according to claim 28, wherein said first carbon matrix has a higher thermal conductivity than said second carbon matrix.  35. The friction disc of claim 28, wherein said first carbon matrix has a higher density than said second carbon matrix.  36. The friction disk according to claim 28, characterized in that said annular porous structure contains carbon fibers.  37. The friction disk according to claim 28, wherein said compacted annular porous structure comprises an annular fibrous structure.  38. The friction disk according to claim 28, wherein said densified annular porous structure comprises an annular fibrous structure having carbon fibers.  39. The friction disk according to § 38, wherein said first annular part has a higher thermal conductivity perpendicular to said two parallel flat surfaces than said second annular part.  40. The friction disk according to claim 38, wherein said first annular part has a higher thermal conductivity perpendicular to said first and second annular surfaces than said second annular part.  41. The friction disk according to claim 38, wherein said first annular part has a higher bulk density of crushed samples than said second annular part.  42. The friction disk according to claim 28, wherein said densified annular porous structure comprises an annular fibrous structure having only carbon fibers.  43. The friction disk according to claims 28 to 42, characterized in that the thermal conductivity measured perpendicular to said two opposite surfaces and the bulk density of the crushed samples from said compacted annular porous structure decrease, as a rule, in the radial direction from said inner annular surface to the specified outer annular surface.  44. The friction disk according to item 43, wherein the specified compacted annular fibrous structure contains carbon fibers.  45. The method of gas phase infiltration of a chemical substance and chemical vapor deposition carried out in a furnace, comprising introducing a reactant gas into a furnace volume in which a sealed heater is located, characterized in that said reactant gas is fed into the heater inlet, removed through the outlet of the heater and dispersed through at least one porous structure located in the specified furnace, the method also includes heating the specified at least one porous page uktury, heating the specified tight heater to a temperature that is higher than the temperature of the specified reagent gas, measuring the temperature of the gas of the specified reagent gas near the specified outlet, regulating the specified temperature of the heater to achieve the desired gas temperature and the release of the specified reagent gas from the specified furnace.  46. The method according to item 45, wherein said furnace contains a wall of the current collector, the method further includes heating the specified wall of the current collector, the study of thermal energy from which the specified heating of the sealed heater is provided.  47. The method according to item 45, wherein the specified sealed heater is located in close proximity to the specified wall of the current collector.  48. The method according to item 45, wherein said furnace contains a wall of the current collector having at least first and second parts, and at least first and second inductors, the first of which is inductively coupled to the specified first part of the wall a current collector with converting electrical energy from said first inductor to thermal energy in said first part of the wall of the current collector, and said second inductor is inductively coupled to said second part of the wall of the current collector with converting electric energy from of a second inductor into thermal energy in said second part of the wall of the current collector, wherein said sealed heater is located near said first part of the wall of the current collector and is heated to said temperature, at least in part, by the thermal energy of radiation from said first part of the wall of the current collector, and with said regulating the temperature of the heater regulates the electric power supplied to the specified first inductor.  49. The method according to item 45, wherein the specified furnace contains a cylindrical wall of the current collector having at least first and second parts, and at least first and second cylindrical inductors, the first of which is coaxially located around the first part of the cylindrical wall of the current collector and inductively coupled to it with the conversion of electrical energy from the specified first cylindrical inductor into thermal energy in the specified first part of the cylindrical wall of the current collector, and the specified second cylindrical the th inductor is coaxially located around the specified second part of the cylindrical wall of the current collector and is inductively connected with it with the conversion of electric energy from the specified second cylindrical inductor to thermal energy in the specified second part of the cylindrical wall of the current collector, while the specified sealed heater is made cylindrical and located coaxially in the specified first part the cylindrical wall of the current collector and in close proximity to it and is heated to the indicated temperature for at least an hour typically, by means of the thermal energy of radiation from the indicated first part of the cylindrical wall of the current collector, and with said temperature control of the heater, the electric power supplied to said first inductor is controlled.  50. The method according to item 45, wherein the specified furnace contains a cylindrical wall of the current collector, and the specified tight heater has, as a rule, an arcuate perimeter and is located in close proximity to the specified cylindrical wall of the current collector.  51. The method according to item 45, wherein the specified sealed heater is heated using electrical energy of a resistive heater.  52. The method according to item 45, wherein the specified outlet of the heater is made in the form of a set of perforations.  53. The method according to item 45, wherein said at least one porous structure has first and second parts, and in the method additionally provide the passage of the specified reagent gas through the specified at least one porous structure from the first parts to the specified second part.  54. The method according to item 53, wherein the deposition of the specified reagent gas of a carbon matrix having a substantially coarse layered microstructure in the specified at least one porous structure.  55. The method according to item 45, wherein the specified at least one porous structure is a carbon porous structure, and the specified reagent gas precipitates a carbon matrix in the specified at least one porous structure.  56. The method according to item 45, wherein said at least one porous structure is made in the form of a series of annular porous structures assembled in a package defining an annular porous wall, and the method further disperses the specified reagent gas through the specified an annular porous wall by feeding and separating from said furnace on opposite sides of said annular porous wall.  57. The method according to p, characterized in that the said package of ring-shaped porous structures has at least one ring located coaxially between each pair of adjacent porous structures, while most of the surface area of each ring-shaped porous structure is free for the action of said gas reagent.  58. The method according to p. 56, characterized in that the said bag has a closed cavity defined by the specified annular porous wall, and the method further supplies the specified reagent gas from the specified outlet of the heater to the specified closed cavity, sealed with the specified outlet .  59. The method of gas phase infiltration of a chemical substance and chemical vapor deposition carried out in a furnace, which includes the formation of an annular porous wall and the supply of carbon-bearing reagent gas to said furnace, characterized in that said porous wall has a closed cavity and is made in the form of a package of annular fibrous carbon structures, the method includes sealing said annular porous wall with a sealed heater having an inlet and an outlet a hole communicating with said closed wall cavity, supplying a reagent gas to said inlet and discharging it through an outlet into said closed cavity, heating said annular porous wall, heating said heater to a temperature that is higher than said reagent gas in said zone heater inlet, measuring a temperature of said reagent gas near said heater outlet, controlling said temperature la to achieve the desired gas temperature and an outlet of said reactant gas from said enclosed cavity of the oven through the opposite side surface of said annular porous wall providing a dispersion of said reactant gas through said annular porous wall.  60. The method according to § 59, wherein said furnace contains a wall of a current collector having at least first and second parts, and at least first and second inductors, the first of which is inductively coupled to said first wall part a current collector with converting electrical energy from said first inductor to thermal energy in said first part of the wall of the current collector, and said second inductor is inductively coupled to said second part of the wall of the current collector with converting electric energy from of a second inductor into thermal energy in said second part of the wall of the current collector, wherein said hermetic heater is located near said first part of the wall of the current collector and is heated to said temperature, at least partially by the thermal energy of radiation from said first part of the wall of the current collector, the temperature of the heater controls the electrical power supplied to the specified first inductor.  61. The method according to p, characterized in that the said reagent gas precipitates a carbon matrix having an essentially coarse layered microstructure in the specified at least one porous structure.  62. The method according to § 59, wherein said packet of annular porous structures has at least one ring located coaxially between each pair of adjacent annular fibrous carbon structures, with most of the surface area of each annular fibrous carbon structure being free for exposure to the specified reagent gas.  63. A device for gas phase infiltration of a chemical substance and chemical vapor deposition, in particular for supplying reagent gas to a furnace containing at least one main gas pipeline for supplying reagent gases, furnace inlet pipes, gas flow control valves, reagent through each furnace feed line and a control controller for said control valves, characterized in that it includes reactant gas flow meters through the furnace feed line, yaschie conduits communicate with main pipelines and said control valves are connected via the controller with flowmeter.  64. The device according to p, characterized in that each furnace inlet pipe contains one flowmeter associated with the controller, and one control valve associated with the specified controller.  65. A device for filtering the gas phase of a chemical substance and chemical vapor deposition, in particular for sealing more porous structures, comprising a furnace, a first gas main and a vacuum apparatus in communication with the furnace volume, characterized in that it includes furnace feed lines communicated with said first main gas pipeline, and porous structures are installed in said furnace in the form of a number of packets of porous structures, each of which has a closed cavity communicated with the furnace inlet pipe and sealed in the indicated furnace volume to ensure the supply of reagent gas to each closed cavity through the specified one furnace furnace inlet pipe and disperse it through the specified porous structures before being discharged from the furnace volume using the specified vacuum apparatus.  66. The device according to p. 65, characterized in that it further comprises a first main control valve located in the specified first main gas pipeline.  67. The device according to p. 65, characterized in that it further comprises first flowmeters for measuring the flow of the first reagent gas through each furnace inlet pipe and first control valves for controlling a specified flow of the first reactant gas through each furnace inlet pipe.  68. The device according to p, characterized in that each furnace inlet pipe contains one first flowmeter that interacts with the controller, and one first control valve, which controls the specified controller.  69. The device according to p. 66, characterized in that it further comprises a second main gas pipeline for supplying a second reagent gas, in communication with the specified supply pipelines of the furnace.  70. The device according to p, characterized in that it further comprises second flowmeters for measuring the flow of the second reagent gas through each inlet pipe of the furnace and second control valves for regulating the specified flow rate of the second reagent gas through each inlet pipe of the furnace.  71. A method of gas phase infiltration of a chemical chemical vapor deposition, in particular densification by gas chemical vapor infiltration and gas vapor deposition, the method comprising: sealing a first porous wall in a furnace by gas chemical vapor infiltration and chemical vapor deposition phase with a pressure gradient, characterized in that the dispersion of the first stream of the reactant gas through the specified first porous wall, the second porous seal walls via the gas phase infiltration process chemical and chemical deposition from the gas phase at a pressure gradient through the dispersion of the second reactant gas flow through said second porous wall and independent control of the first flow of reactant gas parameters and the parameters of the second flow of reactant gas.  72. The method according to p. 71, characterized in that it further includes sealing at least a third porous wall using a process of gas phase infiltration of a chemical substance and chemical deposition from the gas phase at a pressure gradient by dispersing at least a third reagent gas stream through said third porous wall and independently controlling parameters of said third reagent gas stream.  73. The method according to p, characterized in that it further measures the temperature of the first porous wall and its regulation by increasing or decreasing the flow rate of the first stream of reagent gas.  74. The method according to p, characterized in that it further measures the temperature of the second porous wall and its regulation by increasing or decreasing the flow rate of the second reagent gas stream.  75. The method according to p, characterized in that the said seal of the first porous wall is carried out by exposing one side of the first porous wall to the specified first stream of reagent gas at the first pressure and on its opposite side at a vacuum pressure less than the specified first pressure, and said compaction of the second porous wall is carried out by exposing one side of the second porous wall to said second reagent gas stream at a second pressure and to its opposite side at a vacuum pressure less than pressure.  76. The method according to claim 75, characterized in that it further measures said first pressure and controls it by increasing or decreasing the flow rate of the first reactant gas stream.  77. The method according to p, characterized in that it further carry out the measurement of the specified second pressure and its regulation by increasing or decreasing the flow rate of the second stream of reagent gas.

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