Method for control and simulation of gas phase chemical infiltration for carbon compaction of porous substrates

FIELD: chemistry.

SUBSTANCE: invention relates to method for control and simulation of compaction of at least one porous substrate with pyrolitic carbon by chemical gas phase infiltration. According to the method, a lot of one or several substrates to be compacted is placed into furnace, the said substrate is heated, reaction gas containing at least one carbon-source hydrocarbon is supplied to the furnace, pressure, at which reaction gas is capable to diffuse into the heated substrate pores with formation of pyrolitic carbon residue, is established in the furnace, and waste gas is released from the furnace via exhaust pipe connected to the furnace outlet. In waste gas, content of at least one substance chosen from allene, propyne and benzene is determined. According to measured content, process is controlled by setting at least one of the following parameters: flow rate of reaction gas supplied to the furnace, flow rate of at least one component of gas supplied to the furnace, time of gas transit through the furnace, substrate temperature and pressure inside the furnace. At least one of parameters is set so as to provide for almost constant measured gas content. Compaction process can be either controlled in real time or simulated.

EFFECT: possibility of real-time control and simulation of process of compaction of at least one porous substrate with pyrolitic carbon using chemical gas phase infiltration.

12 cl, 8 dwg, 8 tbl, 10 ex

 

The technical FIELD

The invention relates to a seal porous substrates pyrolytic carbon, which is deposited in the pores of the substrate by chemical infiltration in the gas phase.

The scope of the invention is the manufacture of parts made of composite material by sealing the porous fibrous substrates, in particular substrates of carbon fibers, pyrocarbon matrix by chemical infiltration in the gas phase. In this way receive the items from composite carbon-carbon material. Composite carbon-carbon material, thanks to its thermostructural properties suitable for the manufacture of structural parts that use to work at high temperatures, in particular, special parts for engines and structural nodes in aerospace engineering. Frictional characteristics of composite carbon-carbon material also influences its use for the manufacture of friction parts of the brake system and clutch system, for example, brake discs for aircraft and ground vehicles.

PRIOR art

The method of chemical infiltration in the gas phase is well known. In accordance with this method, at least one substrate is placed in an oven to seal in which serves the reaction gas, the soda is containing at least one component, which is the source of the matrix material, which shall be deposited in the pores of the substrate. The flow rate, temperature and pressure are set so that gas can diffuse into the pores of the substrate and to form in them the desired precipitate or one of the components of the decomposition gas, or many interacting components in the gas. To obtain the pyrocarbon matrix using the reaction gas containing at least one gaseous hydrocarbon, capable of decomposition to give a residue of carbon. A typical example of the reaction gas is a mixture of methane and propane, in which the propane acts as "active" gas, which is the main source of pyrocarbon and methane acts as a diluent, contributing to the diffusion of gas into the pores of the substrate and giving part of the deposited pyrocarbon. The method of deposition of pyrocarbon matrix by chemical infiltration in the gas phase (Method PU HIGH) is usually carried out at a temperature from 950°1100°C and a pressure of less than 10 kilopascals (kPa).

There are several options of how PU HIGH, for example, isothermal method and the method in the temperature gradient.

In the isothermal method, the substrate all the time maintained at a temperature, which is essentially the same throughout the volume of the substrate. The disadvantage of this method is that practically N. is possible to obtain a product with a uniform seal. The matrix material is deposited mainly in the pores, which are closer to the outer surface of the substrate. Increasing over time the blockage of surface pores makes it increasingly difficult to access the reaction gas in the thickness of the substrate, resulting in a gradient seal between the surface and inner part of the substrate. Of course, can be mechanically applied to the surface or to remove loose residue from the surface of the substrate one or more times in the compaction process in order to open the surface pores. However, this process must be interrupted for the time necessary to remove the substrate from the Assembly to seal to cool it, remove sediment, re-load the substrate into the machine and heated to the desired temperature. Therefore, the duration of isothermal method PU HIGH increases significantly. In industry, this method of sealing parts such as brake discs for aircraft made of composite carbon-carbon material, it takes several hundred hours.

Using the method with a temperature gradient can largely overcome the above disadvantage. In this way creates a temperature gradient in the thickness of the substrate at which the inside temperature of the substrate is higher than on the surface, which begins to interact R. the special gas. As a result, the matrix material is better precipitates more hot inner region of the substrate. Due to the fact that the surface temperature of the substrate support is lower than the decomposition temperature of the gas or the temperature of the reaction threshold, we can ensure that at least at the initial stage of the process seal, front seal will move inside in the direction of the surface of the substrate. The temperature gradient can be obtained in a known manner by placing the substrate around the current collector connected to the inductor, so that the inner surface of the substrate in contact with the current collector. In addition, the temperature gradient can be obtained by direct inductive connection between the inductor and the substrate in the process of compacting, when the nature of the substrate allows to do it. These methods are described in particular in patent documents FR-A-2711647 and US-A-5348774.

In the document US 5348774 the substrate is heated as by connection to the current collector, and through direct connection with the substrate, because the front seal is moved. For process control sealing is provided by means of carrying out continuous measurement of the mass change of the substrate. Since the process of compaction is a function of the mass change of the substrate, it can be optimized, especially in the sense of the duration, by acting on the parameters of the seals, in particular, the voltage supplied to the coil inductance. The control changes the mass of the substrate can also be used to determine when the end of the compaction process. In comparison with the isothermal method, the method with a temperature gradient really allows you to achieve a more uniform seal, but this method can only be used for the substrate of a certain form, mainly with the substrate, having an annular shape.

Change settings seals in the process of chemical infiltration in the gas phase is described in patent US 6001419. This document describes a method of controlling the microstructure of deposited material. If this material is pyrocarbon, it is known that by changing the conditions of infiltration is possible, in particular, to obtain the pyrocarbon different types: stratified smooth, stratified, dark, layered rough or isotropic. The microstructure of pyrocarbon is a characteristic that is important for the properties of the compacted substrate. For example, parts made of composite carbon-carbon material, it is desirable to have a layered rough microstructure, in particular because it can easily be converted to graphite by heat processing.

The method disclosed in US 6001419, effective to counter the La microstructure deposited pyrocarbon, and, in addition, gives the advantages of a significant reduction in the total duration of the process seal. The process parameters seals can be changed in accordance with the desired model.

The INVENTION

The objective of the invention is to provide a method allowing to control or simulate (i.e. prejudice) process seal porous substrate pyrolytic carbon in real time to optimize the parameters of infiltration, mainly to reduce the total duration of the process seal.

More specifically, the invention is directed to achieving such control or such modeling, which are able to self-regulate with regard to the real conditions of the chemical infiltration in the gas phase.

To solve this problem, a method of monitoring or modeling, in accordance with which: placed in a furnace at least one substrate to be seal, heated specified substrate, served in a microwave reaction gas containing at least one hydrocarbon, carbon source, installed in the furnace pressure at which the reaction gas is able to diffuse into the pores of the heated substrate with the formation of these sediment pyrolytic carbon, and release from the furnace exhaust gas through the exhaust pipe connected the outlet of the furnace.

And, according to the invention, measured in the exhaust of the contents of at least one compound selected from Allen, propene and benzene, and depending on the received content control process by setting at least one parameter selected from: speed of flow of the reaction gas fed into the furnace, the flow rate of at least one component gas fed into the furnace, the time of passage of the gas through the furnace, the temperature to which heat the substrate, and the pressure inside the furnace.

The applicant was found that among the substances contained in the exhaust gas obtained after the decomposition and transformation of the components of the reaction gas, Allen, propyne and benzene are good indicators of the rate of decomposition of pyrolytic carbon, and the content of these compounds in the exhaust can easily be determined.

The method according to the invention allows to optimize the compaction process in real time, which reduces the overall length of the compaction process until you get the desired product density. In addition to reducing the time for manufacturing compacted parts and, consequently, better performance installation for sealing, the method of the invention is applicable for any particular cycle seal with significant is the reduction of energy consumption for heating and consumption of the reaction gas.

The compaction process can be managed successfully supporting the measured gas concentration is essentially constant.

Contents Allen, propene and benzene can be measured in the pipe running parallel to the output pipe for exhaust gas. Measurements can be performed, for example, by gas chromatography.

In one implementation of the invention can be control by regulating the flow rate of the reaction gas or the flow rate of the gas components based on the measured content of Allen or propina.

In another implementation of the invention can be control by regulating the temperature, pressure or time of passage of the gas through the chamber based on the measured content of benzene.

The gas contains at least one source (the source material for receipt) pyrolytic carbon, selected from alkanes, alkynes and alkenes, more specifically, propane, butane and ethane, diluted with methane or natural gas, or inert gas, e.g. nitrogen.

Also preferred is that the end of the densification process is determined by the fact that it becomes impossible to control the change of the measured gas by adjusting the selected parameter. In the result, it is possible to determine the duration of the process seal. The way the image is the shadow provides control of the conditions of the sealing substrate in the chemical infiltration in the gas phase in real time and with the possibility of self-regulation.

For specific installation for chemical infiltration in the gas phase and for a typical substrate, the method provides the possibility of modeling the densification process by performing at least one initial cycle of the seal. Model or template for a predefined change of the setting is saved for subsequent application concerning the same substrate without the need to analyze the exhaust gas. The duration of the compaction process, which can be defined during the modeling stage can also be saved.

BRIEF DESCRIPTION of DRAWINGS

The invention will be better understood from the following description does not limit the invention, with reference to the accompanying drawings, where:

figure 1 shows a very schematic view of an installation for chemical infiltration in the gas phase for implementing the method according to the invention;

figure 2-6 shows graphs of the content of Allen and propene in the exhaust from the mass and density of the substrate;

figure 7 presents a bar graph showing the compaction process controlled by changing the flow rate of one of the gas components based on the measurement of the content of Allen and propene in the exhaust; and

on Fig presents a bar graph showing the compaction process, controlled by the temperature change is and the basis of measurement of the content of benzene in the exhaust.

INFORMATION CONFIRMING the POSSIBILITY of carrying out the INVENTION

Installation for chemical infiltration in the gas phase is very schematically shown in figure 1.

Porous substrates 10, under seal, placed in a furnace 12 having a cylindrical side wall 14, bottom wall 16 and the cover 18. The wall 14 is made of graphite and is a current collector, inductively associated with the coil 20 of the inductance, which is separated from the wall 14 of insulating material 22. This device is placed in a metal casing (not shown).

Example substrates 10 can be ring blanks from carbon fiber. Blanks are stacked in a vertical stack and are separated from each other by separators.

The reaction gas is introduced into the furnace through the supply pipe 24 connected to an aperture in the bottom wall 16. Inside the furnace the gas passes through the zone 11 pre-heating zone 13, where the substrate 10. The pre-heating zone may, for example, consist of a number of perforated graphite plate, heated to the temperature of the furnace. Upon contact with these plates, the reaction gas is preheated before entering the area with the substrate.

Exhaust gas exits through the exhaust hole in the lid 18, which is connected with the outlet pipe 26. This stove pipe connects with the suction device 28, e.g. the, a pump. The valve 29 mounted on the tube 26, allows you to adjust the pressure inside the furnace. One or more devices for cleaning, for example, the trap resin (not shown)may be installed along the pipe 26 from the suction device.

The reaction gas is a mixture of gases stored in cylinders or tanks 30 and 32. For example, you can use a mixture of methane (CH4) and propane (C3H8). Propane or active gas is the main source of pyrolytic carbon, which is released as a result of decomposition at the temperature and pressure maintained within the furnace. Methane acts as a diluent, which promotes the diffusion of gas into the pores of the substrate, and contributes to the formation of pyrolytic carbon. Butane (C4H10), or propylene ethane (C6H6can also be used as "active" gas instead of or in combination with propane. Valves 34 and 36 are installed in the pipes 38 and 40 connecting the tanks 30 and 32 with methane and propane with feed pipe so that it is possible to regulate the flow rate of methane and propane. Valves 34 and 36 regulate by controlling circuit 42. This circuit is also connected to the valve 29 for adjusting the pressure in the furnace and circuit 44 for supplying electricity to the coil 20 of the inductance to adjust the heat in the furnace. Oven SN is beena temperature sensors and pressure (not shown), the feed controlling circuit 42 signals of temperature and pressure in the furnace. The temperature sensor may include at least one optical pyrometer mounted on the cover 18 and measuring the surface temperature of the substrate. The pressure sensor can be installed at the outlet of the furnace.

Mounting type described above are well known in this field.

Pipe 46 connected in parallel to the bypass pipe 26. The device 48 for measuring the content of one or more components in the exhaust, which is a measure of the degree of deposition of pyrolytic carbon on the inside of the substrate 10, is installed in the pipe 46 between the valves 47 and 49. The device 48 may represent, for example, gas chromatograph. As the device 48 can also be used, for example, the device performing the analysis by spectroscopic methods.

The device 48 is connected with the controlling circuit 42, where it sends a signal characterizing the measured content of the component or components. Measurements are performed periodically by a control circuit 42, which opens the valves 47 and 49.

The process of chemical infiltration in the gas phase depends on several parameters, in particular:

- velocity of the reaction gas;

- velocity of the one or more gas components, in particular, as described in visiprise the hinnon example, velocity of the active gas;

- from temperature to which the heated substrate;

pressure inside the furnace; and

from the time of passing the reaction gas through the furnace.

It should be noted that the last two parameters, i.e. the pressure (P) and time (τ) are interrelated, because the time is usually determined by the equation:

where V is the internal volume of the furnace, through which the gas, Q - gas flow rate. Volume V includes the amount of available pores of the substrate loaded into the oven.

Time τ depends on the degree of loading of the furnace and to some extent changed during the process of compaction of the substrate, while the other parameters remain equal.

The applicant was found that among the components of the exhaust gas, Allen a-C3H4, propyne p-C3H4and benzene With6H6are the components, the content of which reflects the rate of formation of pyrolytic carbon and varies depending on one or more of the above parameters of the process seal.

Tests were carried out on the installation type shown in figure 1, but of smaller size than the industrial unit, with volume VRthe furnace is equal to 640 cm3, of which 50 cm3correspond the pre-heating zone. Volume V the furnace is correlated with the above volume V as follows:

VR=V+VS,

where VS- the volume of the portion of the substrate where there are no available pores.

As porous substrates were taken annular fibrous structure of carbon fiber with an outer diameter of 15 mm and thickness of 15 mm, an Initial volume fraction of the substrate, i.e., the fraction of the volume of the substrate occupied by pores was approximately 80%, which corresponds to the initial specific gravity (or relative density)is equal to 0.4. The substrates were placed in a vertical stack and separated from each other graphite separators thickness of 3 mm, so that the intervals between them.

Samples of the substrate were cut from plates made from superimposed on each other and sewn with a needle thin layers. Each thin layer consisted of a multiple sheet made of two unidirectional sheets, i.e. sheets, in which the fibers are parallel to the General direction and unidirectional sheets superimposed on each other in different directions and slightly sutured needle. It should be noted that this type of fibrous structures are well known in the manufacture of brake discs from carbon-carbon composite material.

Test 1

Conducted chemical processes of infiltration in the gas phase using the substrates of the different degree of compaction and in each case with different furnace.

The process parameters were as follows: the reaction gas was a mixture of CH4/S3H8in a volume ratio of 0.9/0.1 to; the temperature is about 1000°C, the pressure is about 1.3 kPa, the time of passing of gas is about 1 second (s).

Table I shows the total measured the content of Allen and propina for substrates with different relative density d, component from 0.4 to 1.55V, i.e. from the substrate at the beginning of the densification process to the substrates at the end of the densification process, for various ratios of m0/VR(in grams per cubic centimeter g/cm3)), where m0- the total initial mass of substrates loaded into the furnace, a VR- the volume of the furnace.

The total content of Allen and propina expressed in volume% in the exhaust.

Table I
Density (d) m0/VR10-2g/cm30,40,70,91,351,55
1,560,61
2,340,72
2,810,43
3,130,69
4,060,24
4,690,5
5,470,14
7,030,37
7,810,45
9,380,150,80
10,940,330,84
15,630,600,80
21,090,76

These results are plotted on the graphs in figure 2-6 for different densities of the substrates.

The dotted lines in figure 2-6 shows the curves 1/R from the values of m0/VRwhere R is the degree of deposition, expressed in grams is Mmax/hour (g/h).

You can see that the total content of C3H4decreases with increasing deposition and that there is a correlation between the degree of deposition and measured gas content. You can also see that the relationship between the mass of the substrates and the total content of C3H4always satisfactory, although to a lesser extent, with increasing density, the weight of the substrate to the total content of C3H4and the degree of deposition is lower for substrates with higher density.

Test 2

The method was the same as in Test 1, except that the time of passage of the gas was increased to 2 seconds.

Table II shows the total measured the contents of C3H4for the same range of loads, as in Test 1.

Table II
Density (α) m0/VR10-2g/cm30,40,70,91,351,55
1,560,43
2,340,50
2,810,30
3,130,48
4,060,17
4,690,35
5,470,08
7,030,26
7,810,32
9,380,110,56
10,940,230,59
15,630,420,55
21,090,51

These results confirm the conclusions made in respect of the Test 1. They also show that there is reduction in the total content3H4with increasing time of passage of the gas.

Test 3

Method the ka was the same as in Test 1, except that the time of passage of the gas was reduced to 0.75 seconds, and the temperature was 1050°C.

Table III shows the total measured content3H4for the same range of loads, as in Test 1.

Table III
Density (d) m0/VR10-2g/cm30,40,70,91,351,55
1,560,69
2,340,84
2,810,48
3,130,79
4,060,28
4,690,59
5,470,13
7,030,44
7,810,53
9,380,180,90
10,940,380,92
15,630,680,87
21,090,82

These results confirm the findings in relation to Tests 1 and 2.

Test 4

The method was the same as in Test 1, except that instead of a3H8used other active gas - butane With4H10in a volume ratio of CH4/S4H10-0,9/0,1.

Table IV shows the total measured content3H4for the same range of loads, as in Test 1.

These results are essentially comparable with the results of the Test 1.

Test 5

The method was the same as in Test 4, except that the time of passage of the gas was increased to 2 seconds.

Table V shows the total measured content3H4for the same range of loads, as in Test 1.

Table IV
Density (d) m0/VR10-2g/cm30,40,70,91,351,55
1,560,67
2,340,80
2,810,47
3,130,76
4,060,26
4,690,55
5,470,12
7,030,41
7,810,49
9,380,160,88
10,940,360,89
15,630,640,84
21,090,80
Table V
Density (d) m0/VR10-2g/cm30,40,70,91,351,55
1,560,47
2,340,56
2,810,33
3,130,53
4,060,18
4,690,39
5,470,08
7,030,29
7,810,34
9,380,110,62
10,940,250,62
15,630,450,59
21,090,55

These results coincide with the results of Test 2.

Test 6

The method was the same as in Test 3, except that instead of a3H8used other active gas - ethane With2H6in a volume ratio of CH4/S2H6- 0,9/0,1, and that the time of passing of gas was increased to 2 seconds.

Table VI shows the total measured the contents of C3H4for the same range of loads, as in Test 1.

Table VI
Density (d) m0/VR10-2g/cm30,40,70,9 1,351,55
1,560,51
2,340,63
2,810,36
3,130,59
4,060,21
4,690,44
5,470,10
7,030,33
7,810,40
9,380,140,68
10,940,290,69
15,630,5 0,65
21,090,62

These results confirm the conclusions made in respect of the Test 1.

Test 7

The method was the same as in Test 1, except that the temperature was about 950°and the pressure is about 1.9 kPa.

Table VII shows the total measured content3H4for the same range of loads, as in Test 1.

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Table VII
Density (d) m0/VR10-2g/cm30,40,70,91,351,55
1,560,39
2,340,50
2,810,27
3,130,47
4,060,16
4,690,35
5,470,07
7,030,26
7,810,32
9,380,110,54
10,940,230,55
15,630,400,52
21,090,49

Test 8

The method was the same as in Test 7, except that the pressure was about 1 kPa.

Table VIII shows the total measured the contents of C3H4for the same range of loads, as in Test 1.

Table VIII
Density (d) m0/VR10-2g/cm30,40,70,91,351,55
1,560,38
2,340,48
2,810,27
3,130,46
4,060,17
4,690,34
5,470,08
7,030,25
7,810,32
9,380,110,52
10,940,240,52
15,630,400,51
21,090,48

The results of tests 7 and 8 are close. The pressure change in Tests 7 and 8 has little effect.

In the processes of chemical infiltration in the gas phase is known from the prior art, traditionally used fixed parameters of the compaction process.

For each parameter it is customary to choose a value that is intermediate between the first value that could be optimal for the beginning of the densification process, when the pores of the substrate are easily accessible, and a second value, which could be optimal when the gas diffusion into the pores of the substrate becomes more difficult. The optimum values are determined, in particular, type the desired microstructure pyrolytic carbon. The first value of the flow velocity of the reaction gas, the concentration of the active gas, temperature and pressure are higher than the second value. An inverse relationship is observed for values of time passing gas.

If you were to choose a constant value for each parameter, which is the optimal value at the end of the process, or very close to it, the degree of deposition would be low and the duration of the process would increase. On the contrary, if you were to choose a constant value, which is the optimal value at the beginning of the process and is very close to it, it would not have contributed to the increase in the degree of deposition at the end of the process, when the degree of deposition depends mainly on diffusion, and would, first, to the risk of premature clogging of the pores of the surface sediments and, secondly, to the deposition of pyrolytic carbon undesirable microstructure, or even to the deposition of undesirable substances, such as soot.

Described tests show that certain components of the exhaust gas is responsible for the degree of deposition and that the contents of these components in the exhaust depends on one or more parameters of the process seal.

In the present invention to optimize the densification process is proposed to control the process of PU HIGH by influencing at least one parameter of the compaction process based on the measured content of one or more particular components of the exhaust gas.

These components are Allen, propyne and benzene. Described tests showed the influence of time of passage of gas and temperature on the content of C3H4. Other tests performed without loading the substrate, showed that the measured content of Allen and propina depends on the content of the active gas in a mixture of reaction gas and its flow rate, and that the measured benzene content depends on the temperature. The adjustment to the each parameter of the compaction process, in which decide to have an impact, carried out in a range of values. For various of the above-mentioned parameters, the maximum value is one which can be set at the beginning of the densification process. It is chosen, in particular, depending on the characteristics of the porosity of the substrate and on the type of the desired microstructure pyrolytic carbon. The minimum value is below which it is not desirable or impossible to hold the end of the densification process.

For example, to seal substrates from carbon fibers of the type commonly used for the manufacture of parts made of composite carbon-carbon material, in particular, brake discs for aircraft, and for the formation of pyrolytic carbon from layered rough microstructure, you can use the following ranges of parameters:

temperature between 900°and 1100°to obtain a desired microstructure pyrolytic carbon;

- the pressure is between 0.1 kPa and 10 kPa to obtain a desired microstructure pyrolytic carbon and to address the technical difficulties of creating and maintaining a very low pressure in the furnace;

the time of passage of the gas of 0.5-5 seconds, especially in order to eliminate excessive gas retention, which can lead to the formation of undesirable deposits; and

volume from which compared active gas, in particular, propane, butane or ethane in the reaction gas mixture containing methane and one or more active gases is in the range of 0-70% or 0-100%as possible, so that the reaction gas consisted only of active gas in the beginning of the seals.

The total rate of flow of the reaction gas is determined by the mass of fibrous substrates, which are subject to compaction, thus, to ensure that each substrate has been treated with the reaction gas.

Because the degree of deposition in the beginning of the process of compaction is determined rather by the multiplexing options, and not the ability of the gas to diffuse into the substrate, it is preferable to choose as the initial values of the varying parameters the maximum value of the predetermined range or a value close to the specified maximum value, excluding the time of passage of the gas for which it is preferable to choose the minimum or close to minimum value.

The process is controlled in such a way as to maintain the contents of Allen, propene and benzene essentially constant or equal to the value at the beginning of the densification process. This reference value may be a value measured in a few hours, or a value that is an average of several measurements made in the beginning of the process to achieve its stabilizat is I. As the process develops slowly, it is not necessary to measure the controlled content constantly. Enough measurements periodically, for example, at intervals of 0.25 to 1 hour.

The measured content can be maintained essentially constant, provided that it is in the range [T-20%, T+20%], where T is the control value set in the beginning of the process.

In practice, maintaining the measured content is essentially constant leads to the fact that other parameters seals gradually decrease, except for the time of passage of the gas, which increases.

The end of the densification process is determined by the fact that the adjustment of the selected variable parameter can not longer maintain the measured content is essentially constant value in a predefined range. In practice, in this case, there is an uncontrolled increase in the measured content. Consider that the end of the densification process came when the measured content exceeds a threshold that is equal to or greater than the upper limit of the range of values for this content.

Examples of implementation of the method according to the invention are described below.

The furnace was loaded with many fibrous substrates with an initial density of 0.4 and the ratio of m0/VR=5,47×10-2g/cm3. The substrates plot the Yali to achieve a density of about 1.6.

Example 1

Used reaction gas containing a mixture of CH4/S3H8. Was in the process of chemical infiltration by setting the temperature inside the furnace is approximately 1000°C, the pressure is about 1.3 kPa, and the time of passage of the gas - 1±0,30 seconds, and change the time of passage of gas were directly related to changes in the flow velocity.

The content of Allen and propene (the total content of C3H4) was measured periodically, and the content of C3H8in the mixture gas was set circuit 42, the control valve 36 so as to maintain the measured content is essentially equal to 0.2. In the beginning of the process, the proportion of active gas, i.e. the molar percentage3H4in the reaction gas should be 50%.

7 shows how the measured content3H4and the proportion of C3H8with the passage of time. You will notice that maintaining the overall content With3H4at almost a constant level leads to a decrease in the proportion of the active gas, until it is reduced to about 5% at the end of the densification process.

For comparison was in the process of deposition of pyrocarbon matrix by chemical infiltration in the gas phase (process PU HIGH) under similar conditions, except that the molar proportion of the active gas With3H8supported pic is annoy and equal to 10%. To achieve a relative density of about 1.6 it took 40% longer than during the process of PU HIGH with the change in the molar proportion of the active gas.

Example 2

Used reaction gas composed of a mixture of CH4/S4H10. Was in the process of PU HIGH, setting the pressure in the furnace of about 1.0 kPa and the time of passage of the gas is approximately 1 second.

The content of benzene (C6H6) was measured periodically, and the temperature in the furnace was installed by circuit 42, the control circuit 44 of the supply voltage so as to maintain the measured content is essentially equal to the value measured at the beginning of the densification process. In the beginning of the process temperature set value 1100°C.

On Fig shows how changing the measured content6H6and temperature over time. You will notice that maintaining the measured content6H6at almost a constant level leads to a decrease of the temperature to 950°at the end of the densification process.

For comparison was in the process of PU HIGH under similar conditions, except that the temperature was maintained constant and equal to approximately 1000°C. To achieve a relative density of about 1.6 it took 30% longer than when carrying out the process with treason is receiving temperature.

Examples 1 and 2 confirm the efficiency of the method according to the invention for reducing the time required for sealing through the optimization process PU HIGH. This reduction of time leads to the decrease of flow of the reaction gas and to decrease the content of some substances, such as polycyclic aromatic hydrocarbons, in the exhaust.

Although examples 1 and 2 reflect the impact on only one of the parameters of compaction, the compaction process can change several parameters.

The method according to the invention is applicable to control the compaction process in real time by measuring the content of Allen, propene and/or benzene in the exhaust and install at least one parameter of the compaction process.

The method according to the invention is also applicable to simulate the compaction process for the specific installation for chemical infiltration and for typical loading of the substrate subject to compaction. During one or more cycles seals for modeling purposes, it is possible to set at least one parameter of the compaction process as a function of the measured content of Allen, propene and/or benzene. Changing at least one or each set, and the duration of the process seal preserve. The resulting model can EAP is due to play for sealing substrate of the same type, repeating the modifying of the same parameters for the same duration of the compaction process, as in the model cycle.

Although the invention is described with reference to the process seal of the party of substrates, which is a stack of annular workpieces, it is also applicable for sealing substrate of any shape.

1. The method of monitoring or modeling the densification process at least one porous substrate pyrolytic carbon by chemical infiltration in the gas phase, in accordance with which: placed in a furnace batch of one or more substrates that are subject to condensation, heat up the specified substrate, served in a microwave reaction gas containing at least one hydrocarbon, carbon source, installed in the furnace pressure at which the reaction gas is able to diffuse into the pores of the heated substrate with the formation of these sediment pyrolytic carbon, and release from the furnace exhaust gas through the exhaust pipe connected with the outlet of the furnace, characterized in that is measured in the exhaust of the contents of at least one compound selected from Allen, propene and benzene, and depending on the received content control process by setting at least one parameter selected from the flow velocity of the reaction gas, podemos is in the oven, flow rate of at least one component gas fed into the furnace, the time of passage of the gas through the furnace, the temperature to which heat the substrate, and the pressure inside the furnace.

2. The method according to claim 1, characterized in that at least one parameter set so that the measured gas content was maintained essentially constant.

3. The method according to claim 1, characterized in that the gas content is measured in the pipe running parallel to the output pipe.

4. The method according to claim 1 or 3, characterized in that the gas content measured by gas chromatography.

5. The method according to claim 1, wherein setting at least one parameter is carried out by regulating the flow rate of the reaction gas or the flow rate of the components of the reaction gas based on the measured content of Allen and/or propene.

6. The method according to claim 1, wherein setting at least one parameter is carried out by regulating the temperature to which heat the substrate, depending on the measured content of benzene.

7. The method according to claim 1, wherein the reaction gas contains at least one component selected from alkanes, alkynes and alkenes.

8. The method according to claim 1, wherein the reaction gas contains a component selected from propane, butane and ethane, razbam the military methane.

9. The method according to claim 1, wherein the selected parameter set in a predetermined range of values.

10. The method according to claim 9, characterized in that the end of the densification process is determined by the fact that it becomes impossible to control the change of the measured gas by adjusting the selected parameter.

11. The method according to claim 1, wherein implementing changes at least one parameter that was set keep your change and get a model that is reproducible in subsequent processes seals the party of the same type.

12. The method according to claim 10 or 11, characterized in that preserve the length of the compaction process.



 

Same patents:

FIELD: physics, guidance.

SUBSTANCE: invention concerns field of automatic control and is intended for pulsing transformers of a voltage, wide application in guidance of electric drives and adjustable secondary power supplies can find. Carry out guidance of the voltage transformer switching of a key device on a sign of the driving signal, thus a driving signal shape as the total of current values of pulsing making energy of a choke of the filter and the energy necessary for a filter capacitor for achievement of the given target voltage.

EFFECT: simplification of formation of driving signal for systems with pulsing transformers of voltage with LC-filter.

1 dwg

FIELD: physics, guidance.

SUBSTANCE: invention concerns automatics field, in particular, to guidance of the process having of some mechanisms of feedback control. Controller includes the first and second modules of servomotor control which generate the first and second leading signals on the basis of the information of a feedback from the first and second data units for guidance of a control mean of process according to the first and second control modes, accordingly. The controller also includes the module of transmission of feedback control which transfers control of operation of a control mean of process of the first control mode in the second control mode on the basis of the information of a feedback from the first data unit. In some versions, such transmission of guidance guesses the program of guidance which initiatingly generates the second leading signal on the basis of the first leading signal for the purpose of maintenance with smooth, without shocks, guidance transmission between control modes.

EFFECT: increase of reliability of operation of a control system.

31 cl, 5 dwg

FIELD: physics, guidance.

SUBSTANCE: invention concerns automatics field, in particular, to guidance of the process having of some mechanisms of feedback control. Controller includes the first and second modules of servomotor control which generate the first and second leading signals on the basis of the information of a feedback from the first and second data units for guidance of a control mean of process according to the first and second control modes, accordingly. The controller also includes the module of transmission of feedback control which transfers control of operation of a control mean of process of the first control mode in the second control mode on the basis of the information of a feedback from the first data unit. In some versions, such transmission of guidance guesses the program of guidance which initiatingly generates the second leading signal on the basis of the first leading signal for the purpose of maintenance with smooth, without shocks, guidance transmission between control modes.

EFFECT: increase of reliability of operation of a control system.

31 cl, 5 dwg

FIELD: physics, guidance.

SUBSTANCE: invention concerns field of guidance of ecological safety in emergencies at the enterprises of the chemical, petrochemical, oil refining and gas-processing industry. The system is intended for the equipment of the columned type having major diameter of the inferior part. The system consists of self-acting systems: 1) liquid phase gathering at decompression of the apparatus executed in the form of a trench, welded on outside perimetre of the apparatus and a drain pipe for an overflowing of a liquid phase from a trench in female capacity, with its subsequent pumping-out on treatment facilities; 2) systems of dispersion of a gaseous cloud of an explosive yield water steam through the punched collector welded on an outside surface of the kettle above a trench of gathering of a liquid phase. The system has the control block of fire and explosion hazard situations.

EFFECT: increase of reliability of operation of system of automatic control and regulation and reduction of its dimensions.

4 dwg

FIELD: physics.

SUBSTANCE: proposed method of pinpointing faulty pickup in a surplus system consists in periodical checking up of the relationship between the measured parameters of motion describing normal operation of pickups and the disturbed aforesaid relationship to set the motion, after revealing said disturbances, wherein the output signal of either of the selected three pickups is set to be lower than a certain preset minor value Δ. It also comprises recording the control pickup readings, varying the scaling factor of three pickups selected to control purposes and pinpointing faulty pickup proceeding from the measurement results.

EFFECT: expanded performances thanks to opportunity of pinpointing faulty pickup with shift signal slowly varying.

1 dwg

FIELD: physics, computer equipment.

SUBSTANCE: invention is related to modeling systems. Method for object manufacture that has potential {x}, generated as response to the field {f} imposed on it, includes stage of object geometric model design. Mathematical model processed with the help of computer is generated by means of object geometric model discretisation into multiple final elements and determination of units at element borders, at that in units values of field {f} and potential {x} are established. Then matrix [k] of material properties is calculated on the basis of ratio {f}=[k]{x}. Then coefficients of material properties are recovered from matrix [k] of material properties for every final element in mathematical model processed with the help of computer, and recovered coefficients of material properties are compared to coefficients of material properties for known materials, in order to coordinate recovered coefficients of material properties with coefficients of material properties for known materials. Then production parameters are determined that correspond to coordinating coefficients of material properties.

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14 cl, 13 dwg

FIELD: physics; control.

SUBSTANCE: invention is related to automatic control systems on the basis of computer equipment. Complex of remote automatic control of engineering equipment of enterprise buildings contains central computer module with input-output unit that represents programmed controlling server intended for monitoring and control of complex equipment, and, at least, one computer station, which is connected with its input-output module through local computer network to central computer module. Complex contains converters of ETHERNET - RS-485 interface, which are connected to central computer module through local computer network of enterprise, at that at least one symbolic circuit is connected to every converter of interface, as well as remote modules of input-output, to every of which appropriate sensor or device is connected for control of specific aggregate of engineering equipment.

EFFECT: creation of remote automatic control complex, which provides reduction of power losses, increase of operation life resources and safety of equipment.

1 dwg

FIELD: physics, control.

SUBSTANCE: invention is related to multi-level controller that controls operation of system, which performs technological process. Process has multiple process parameters (MPP): one of MPP is controlled process parameter (CTPP) and one of MPP is target process parameter (TPP); and designated target value (DTV), which represents the first limit of actual average value (AAV) of TPP in preset period of time with duration TPLAAV2. AAV and is calculated on the basis of actual values (AV) of TPP in preset period. The first logic controller predicts future average values (FAV) of TPP for the first future time period (FFTP), which has duration TPLAAV2 and starts from the current moment of time T0 to the future moment of time TPLAAV2, before which TPP switches over to steady mode. FAV are predicted on the basis of (i) AAV TTP in different moments of time in the first preceding time period (FPTP) with duration of at least TPLAAV2, which continues from preceding time TPLAAV2 to current time T0, (and) current values of MPP, and (iii) DTV. The second logic controller sets additional target value (FTV), which represents the second limit of AAV TTP for the second future time period (SFTP), which has duration equal to TPLAAV2, which is less than duration TPLAAV2, and starts from current time T0 to future time TPLAAV1. FTV, being established on the basis of one or more predicted FAV TPP in FFTP.

EFFECT: higher efficiency of system operation control.

24 cl, 28 dwg, 3 tbl

FIELD: physics; control.

SUBSTANCE: invention is related to the field of automatics and may be used for control of chemical, power-producing, electromechanical and other objects with alternating or non-stationary parameters. Adaptive control system contains regulator, summator, control object, three amplitude and phase meters, unit of phase frequency self-tuning, generator, computer unit, computer of amplitude-phase characteristic, unit of amplitude self-tuning. Connection of mentioned elements of adaptive system is executed according to application documents.

EFFECT: exclusion of band-stop filter from circuit; expansion of amplitude range of operation; make it possible to operate with low amplitude at the output from control object, expansion of application field.

3 cl, 3 dwg

Relay regulator // 2342690

FIELD: physics; control.

SUBSTANCE: present invention pertains to automatic control technology, particularly to the technology of generating control signals. The relay regulator contains, in each of (2m+1) channels, an analogue-to-digital converter, memory device, digital comparator, pulse generator, pulse counter, trigger, multiplexer, first and second majority elements, OR and XOR elements. The given parameters of duration τd and interval τi of the control signal as a function of the input signal are stored in the memory device and due to continuous comparison of real values with given values, the relay regulator does not cause delays in the control system. Due to defined connections, correct functioning of the relay regulator can be achieved when there are faults in m channels of the regulator. The proposed relay regulator can be used in different control systems, particularly in spacecraft.

EFFECT: increased efficiency.

1 dwg

FIELD: technological processes.

SUBSTANCE: invention is related to metal coatings that are applied by means of chemical-thermal deposition from steam phase, and also to products and methods. Metal-containing precursor is transported in transport medium via chamber to base at temperature in transport volume that is less than temperature of metal-containing precursor decomposition. Deposition of metal layer onto base is carried out by means of decomposition of metal-containing precursor on base. Temperature at base is higher than decomposition temperature of metal-containing precursor. Temperature of base and temperature of metal-containing precursor in transport volume are measured directly. Rate of deposition and quality of mentioned metal layer on specified base is controlled by means of regulation of specified base temperature and temperature of metal-containing precursor in transport volume with application of transport mediums that are saturated with precursor. Temperature is regulated between transport mediums and base and during maintenance of conditions for transport mediums that are at least close to saturation.

EFFECT: improves quality of thin film from deposited material and significantly reduces formation of metal dust.

44 cl, 10 dwg, 2 tbl, 12 ex

FIELD: inorganic chemistry.

SUBSTANCE: invention relates to the method of forming thin films of oxide on the surface of carrying base, a device for forming thin films (variants), and thin film forming process monitoring methods, and can be used during production of packages in different industries. A gaseous mixture containing gaseous monomer and an oxidising reaction gas is converted into plasma by changing the ratio of the gaseous monomer flow value to the reaction gas flow value so that the said ratio is within a set range of over 0 to 0.05. This allows to form thin films with gas protection properties stably and without deviations. In the process of thin film formation, it is determined if a thin film with the required surface properties is formed, by measuring the intensity of the α line of hydrogen and the oxygen emission, which are radiated by the plasma during the thin film formation. The measured values are compared to the corresponding reference intensity values, at which thin films with required layer properties were obtained. The corresponding devices are also developed for the forming and monitoring methods.

EFFECT: formation of thin films with gas protection properties.

17 cl, 11 dwg, 19 ex, 6 tbl

FIELD: technological processes.

SUBSTANCE: electrode that surrounds the receptacle and forms part of pressure reduction chamber intended for receptacle installation and electrode that is installed next to receptacle neck above its opening are installed one opposite to each other and separated with insulating body. This body forms part of pressure reduction chamber. Inlet tube of gas is made of insulating material for guiding gas that is supplied to the mentioned chamber with the help of supply facility of gas that is transformed into plasma for application of diamond-like film of coating onto receptacle wall internal surface. Tube is installed on facility for exhaust of gas that is available in pressure reduction chamber from the bottom part of receptacle part with opening. High-frequency supply facility is connected to electrode that surrounds receptacle, therefore, it is possible to freely ignite plasma and execute discharge.

EFFECT: stabilisation of plasma discharge and prevention of dust adhesion to electrode.

16 cl, 12 dwg, 2 ex, 2 tbl

FIELD: metallurgy.

SUBSTANCE: invention refers to plastic package with inside surface of wall coated with diamond-like film; invention also refers to device for fabricating this package and to method of package fabricating. The device contains an electrode encompassing the package and forming one portion of a chamber for pressure fall where the package and a facing electrode located inside the package above an aperture are arranged. The said electrodes face each other and are divided with an insulating body forming portion of the pressure fall chamber. A device for source gas supply contains an inlet pipe of supplied gas. There are also a pumping out device and a device of high frequency supply. The method includes pumping out the package contents till achieving the pressure less or equal to specified, then introduction of source gas for generating plasma, termination of pumping out and decreasing the rate of introduction of the source gas to the value less than the rate of introduction at the moment of change, generating plasma for formation of diamond-like carbon film on the interior surface of the plastic package wall. Thus the package with film is produced; the said film has equal level of oxygen impenetrability; and colouring of film formed at the throat portion of the package is avoided.

EFFECT: production of package with diamond-like carbon film with uniform level of oxygen impenetrability.

25 cl, 24 dwg, 7 tbl

FIELD: carbon particles.

SUBSTANCE: invention relates to technology of preparing particles having monocrystalline diamond structure via growing from vapor phase under plasma conditions. Method comprises step ensuring functioning of plasma chamber containing chemically active gas and at least one carbon compound and formation of reactive plasma, which initiate appearance of seed particles in the plasma chamber. These particles ensure multidirectional growing of diamond-structured carbon thereon so that particles containing growing diamond are formed. Functioning of plasma chamber proceeds under imponderability conditions but can also proceed under gravitation conditions. In latter case, seed particles and/or diamond-containing particles in reactive plasma are supported under effect of external gravitation-compensating forces, in particular by thermophoretic and/or optic forces. Temperature of electrons in the plasma are lowered by effecting control within the range from 0.09 to 3 ev. Chamber incorporates plasma generator to generate plasma with reduced electron temperature and device for controlling forces to compensate gravitation and to allow particles to levitate in the plasma with reduced electron temperature. This device comprises at least one levitation electrode for thermophoretic levitation of particles in plasma with reduced electron temperature or an optical forceps device.

EFFECT: enabled efficient growing of high-purity duly shaped particles with monocrystalline diamond structure having sizes from 50 μm to cm range (for instance, 3 cm).

19 cl, 5 dwg

FIELD: processes of chemical infiltration or chemical deposition from vapor phase, case hardening in furnace.

SUBSTANCE: method is used for monitoring process realized in furnace with use of gas reagent containing at least one gaseous hydrocarbon. Method comprises steps of adjusting working parameters of furnace; adding into furnace gas-reagent containing at least one gaseous hydrocarbon; discharging from furnace exhaust gases that contain by-products of gas-reagent reaction; washing out exhaust gases by means of oil that absorbs resins present in exhaust gases; receiving information related to process according to measured quantity of resins absorbed by oil. It is possible to change working parameters of furnace such as temperature, pressure in furnace, gas-reagent consumption and composition.

EFFECT: possibility for monitoring process in furnace without special apparatus of infiltration furnace.

14 cl, 1 dwg, 1 ex

FIELD: the invention refers to application of covers in a liquefying layer particular to an arrangement for settling covers in a liquefying layer.

SUBSTANCE: the arrangement for settling covers in a liquefying layer has a chemical reactor of a cylindrical form and a system of feeding with liquefiable gas, the inner surface of the cylindrical reactor is provided with vertical grooves located on ribs of regular polygons inscribed into the inner diameter of the reactor. At that the number of grooves is chosen in the limits 3-20, the grooves in the section have a form of an equilateral triangle and for a reactor with a diameter of 20-100 mm the relation of squares of transversal sections of the reactor and of all grooves is in the limits 100-200.

EFFECT: the invention provides stability of a liquefying layer at essential increasing of the particles' mass in the process of applying a cover.

1 cl, 1 dwg

FIELD: metal science; protection of materials against external and corrosive attacks.

SUBSTANCE: proposed method for producing diamond-like films designed for encapsulating solar photocells to protect them against chemical, radiation, and mechanical damage includes variation of ion kinetic energy, plasma discharge current, and spatial density distribution of plasma incorporating C+, H+, N+, and Ar+ ions by acting upon ion current from radial source with electric field built up by stop-down, neutralizing, and accelerating electrodes. Spatial plasma distribution is checked for uniformity by measuring plasma current density on solar photocell surface whose temperature is maintained not to exceed 80 oC. In the process substrate holder makes complex axial movement in three directions within vacuum chamber. Diamond-like films produced in the process on solar photocell surface area over 110 cm2 are noted for uniformity, difference in their optical parameters variable within desired range is not over 5%.

EFFECT: enhanced adhesive property, microhardness, and resistance of films to corrosive attacks.

5 cl, 12 dwg, 2 tbl

The invention relates to the production of carbon ceramic products with pyrocarbon coatings in chemical engineering, nuclear and electronic industries

The invention relates to the field of chemical deposition from the vapor phase and, in particular, to plazmostimulirovannom chemical deposition from parasol phase of high-quality diamond-like carbon films on partially restricted surfaces or surfaces with a high degree of uncouthness
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