RU2603330C2 - Method of producing multifunctional ceramic matrix composite materials (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of multifunctional composite materials with ceramic matrix of silicon carbonitride, formed on a base of porous reinforcing frame, made from carbon fabric or fibre in form of threads, bundles or layered filaments with a continuous or discrete structure. Such materials are used in power heat-loaded parts of aircraft, combustion chambers and other items for aerospace and aviation equipment. Disclosed method of producing multifunctional ceramic matrix composite materials in volume of porous reinforcing frame, made from carbon fabric or fibre in form of threads, bundles and layered filaments with a continuous or discrete structure, comprises forming a ceramic matrix of silicon carbonitride by chemical vapour deposition (CVD) of silane with nitrogen-bearing precursor to preset density and process of multiple cyclic impregnation of frame with preceramic polymer (silazane) with subsequent polymerisation and pyrolysis (SPP). Chemical deposition is carried out in gas-vacuum furnace at temperature 500…900 °C and pressure of 50…500 Pa, and repeated (from 2 to 4 times) cyclic impregnation of frame with preceramic polymer and subsequent polymerisation and pyrolysis is performed in vacuum compression furnaces at temperature of up to 1,600°C and pressure of up to 20 MPa. Another version of method comprises first a step of SPP, and then CVD.

EFFECT: technical result of patented versions of method is production of ceramic matrix composite materials with density in range of 1,8- 2,1 g/cm³, resistance to mechanical and thermal cyclic loads and level of oxidation resistance at 400-1,400 °C.

10 cl, 2 tbl, 3 ex

Description

The invention relates to methods for producing composite materials, namely multifunctional composite materials with a ceramic matrix of silicon carbonitride, formed on the basis of a porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure, as well as to processes a different combination and sequence of implementation of which under appropriate modes of technological influences provides an increase in environmental safety and technical and economic efficiency of the implementation of the method.

The proposed composite materials are intended for use in power heat-loaded parts of aircraft, combustion chambers of products and equipment of rocket and aviation equipment, the outer surfaces of reusable spacecraft, as well as for the manufacture of parts and assembly units of equipment of the energy, electronic, oil and other industries working in elevated temperatures in chemically active environments.

Currently, various methods for producing ceramic composite materials (CMC) are known. The most widespread in Russia and abroad are liquid-phase silicon-carbon-carbon composite melt siliconization technologies and chemical vapor deposition (CVD) technologies, where methyltrichlorosilane (CH ₃ SiCl ₃ ) is the main reagent to obtain a silicon carbide matrix. [Lacombe A., Bonnet C. Ceramic Matrix Composites, key materials for future space plane technologies // 2-nd Inter. AerospacePlanesConf. (Orlando, Oct. 29-31). 1990. - P. 1-14].

The disadvantages of the method of producing a silicon carbide matrix from methyltrichlorosilane (MTS) include the use of volatile explosive, corrosive, poisonous starting components (MTS and methane) in the CVD process and, as a result, the formation of environmentally hazardous chlorine-containing products (HCl, SiHCl ₃ , SiCl ₄ and other). This necessitates the observance of special safety measures when disposing of unreacted initial reagent and process wastes, the use of special high-temperature corrosion-resistant materials in equipment and measures for their protection, advanced training and additional personnel protection, which requires significant material and energy costs for their implementation.

In addition, the decomposition of MTS or a mixture of MTS and methane proceeds with the formation of impurities from carbon and silicon, which impairs the strength and oxidation properties of CMCs. The processes for producing composite materials with a silicon carbide matrix from the gas phase of other chlorosilanes or silicon chloride SiCl _{4 are} characterized by the same disadvantages as the deposition process from MTS.

Known developed in Russia, an environmentally friendly method of deposition of silicon carbide in porous bodies from the gas phase containing monomethylsilane (CH ₃ SiH ₃ ). The method provides for the production of composite materials homogeneous in composition and physico-mechanical characteristics, allows to reduce the temperature and simplify the hardware design of the HOGF process. [Timofeev AN, Bogachev EA, Gabov AV, Abyzov AM, Smirnov EP, Persia M.I. A method of obtaining a composite material. RF patent No. 2130509, priority of 01/26/1998].

Increased resistance to thermocyclic loads among ceramic composite materials are materials with a matrix of silicon carbonitride. This is due to a combination of two factors: firstly, silicon carbonitride according to the Kineri criterion (in the foreign literature “FOM-FigureofMerit”) has a significantly (3 to 10 times) higher resistance to thermal shock, which allows it to accumulate defects to a lesser extent with each heating-cooling cycle; secondly, silicon carbonitride chemically precipitated from the gas phase does not undergo phase transformations up to temperatures of at least 1400 ° C, which also allows the silicon carbide-silicon matrix not to acquire new microdefects during operation. [Riedel R. Handbook of ceramic hard materials. Hoboken (NJ): WILEY-VCH, 2000. Vol. 2. 476 p., Lee J.Y. Fabrication of SiCN thin film on substrate and measurement of sheetresistive // University of Colorado at Boulder. URL: www.colorado.edu/engineering/MCEN/MCEN5208/lit_lee.pdf (accessed: 01.12.2008)].

A common drawback of the implementation of the CVD process is the long formation time of ceramic matrices, which is usually from 600 to 1200 hours with a low utilization rate of preceramic gaseous compounds (not more than 10%).

To reduce technological time, an unsteady thermal field is used to localize the chemical reaction zone, or the supply of reagents is increased. Such approaches reduce the economic efficiency of the technological process and complicate the design of technological equipment.

Known pulse method of supplying a gas mixture to a chemical reactor. The method is characterized by a significantly higher yield of the ceramic phase from the initial precursor, but at the same time, the duration of the chemical deposition process is significantly more than doubled. [Naslain RR; Pailler R; Bourrat X. et al. Synthesis of highly tailored ceramic matrix composites by pressure-pulsed CVI. // Solid State Ionics, 2001. - Vol. 141. - P. 541-548].

Over the past two decades, liquid-phase methods for the formation of ceramic matrices from pre-ceramic polymers have been actively developed, which are characterized by higher efficiency and the rate of formation of the matrix material in comparison with the processes of CVD.

EP patent No. 1063210 B1 (published October 15, 2003) proposes a method for producing CMC, including the process of forming fabrics from inorganic fibers, processing the surface of the fibers, providing a coating layer on the surface of these fabrics, as well as obtaining a matrix formed on them basis. The indicated matrix formation process consists of a polymer crosslinking step to form a copolymer consisting of polycarbosilane (PCS) and polymethylsilane (PMS). They are stitched together by holding the mixture of organic polymers for a predetermined time at a temperature of 573 K to 723 K, which is lower than the pyrolysis temperature of both polymers. Next, a polymer impregnation process is implemented to introduce the copolymer mixture into the material, followed by a pyrolysis step in an inert atmosphere to complete the previous processes.

, G. D. (2013) Polymer-Derived Ceramics: 40 Years of Research and Innovation in Advanced Ceramics, in Ceramics Science and Technology Volume 4: Applications (eds R. Riedel and I.-W. Chen), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany].The main disadvantages of the proposed methods include the fact that the resulting ceramic matrix composite materials have a matrix of silicon carbide, are characterized by lower physicomechanical characteristics and oxidative stability compared to materials whose matrix was obtained in the course of CVD. [Colombo, P., Mera, G., Riedel, R. and

, GD (2013) Polymer-Derived Ceramics: 40 Years of Research and Innovation in Advanced Ceramics, in Ceramics Science and Technology Volume 4: Applications (eds R. Riedel and I.-W. Chen), Wiley-VCH Verlag GmbH & Co . KGaA, Weinheim, Germany].

US patent No. 7012035 (published March 14, 2006) discloses a method for producing material from a fibrous ceramic composite made of: a) a dense fabric or a bundle of three-dimensional oriented fibers with high thermal conductivity, b) a crystal matrix of β-silicon carbide, which is obtained in the process of chemical vapor deposition onto fibers; c) the matrix component of β-silicon carbide in the process of impregnation and pyrolysis accumulates in the pores of the tissue structure; g) the future component of β-silicon carbide is obtained in the process of chemical deposition in the pores and cracks of the material obtained in the previous pyrolysis process.

The main differences and disadvantages of this method are the use of highly heat-conducting fibers, which are characterized by reduced physical and mechanical properties and the fact that the matrix of the composite material consists only of silicon carbide. The result is a material having low tensile strength, low resistance to mechanical and thermal shock, which limits its use in parts of gas turbine, rocket engines, on the outer surfaces of reusable spacecraft, and parts of chemical equipment.

The closest analogue of the first variant of the claimed method is a method for producing ceramic composite materials (US 5459114, class С04В 35/58, publ. 10/17/1995), in which a ceramic matrix is formed from a porous reinforcing frame made of carbon fabric silicon carbonitride by chemical vapor deposition followed by repeated (2 times or more) impregnation with a polymer (polysilazane) with polymerization and pyrolysis (SPP).

However, the proposed method has the following significant disadvantages. When implementing this method, known combinations and sequences of technological effects are used. The description of the method and examples of its implementation do not contain information about the parameters: the initial density of the frame, the volume content of the reinforcing filler depending on the stage of saturation, etc., and the modes of the processes. In this regard, it is very difficult to predict the technical and operational characteristics of the obtained composite materials and, accordingly, the functional purpose of the products and their scope.

The closest analogue to the second variant of the claimed method is a method for producing a highly filled ceramic matrix material according to US patent document No. 2011/0071014 A1 (published March 24, 2011), which includes: forming a matrix blank of non-oxide ceramic and continuous ceramic fibers with an external coating; partial saturation of the preform with polymer during the impregnation process followed by polymerization and pyrolysis (SPP); saturation of the workpiece by chemical vapor deposition (CVD) to a density of at least 95% of theoretical. In this case, oxide-free ceramic is selected from the group consisting of silicon carbide, silicon nitride, silicon carbonitride ceramics, or a mixture thereof. The composite billet is impregnated with resin, followed by its decomposition until a composite of the required density is formed, the preform is saturated from the gas phase to increase the density and reduce the porosity of the ceramic composite material with a final density of at least 90% of theoretical.

However, the proposed method has the following significant drawbacks, among which the low environmental safety of the processes for producing matrix material due to the use of methyltrichlorosilane (CH ₃ SiCl ₃ ) as a pre-ceramic chlorine-containing gas precursor in the chemical vapor deposition process. As a result of the decomposition of this gas, a reaction occurs with the formation of hydrochloric acid (HCl), which has a third degree of danger. In addition, the proposed method involves the use of a reinforcing cage made of silicon carbide fibers, which have lower physical and mechanical characteristics than carbon fiber, and only one combination of CVDF and PPP processes for creating an oxidation-resistant matrix is proposed, which limits the ability to control the functional properties and cost of the final composite material.

The closest analogue to the third variant of the claimed method is the method disclosed in patent EP 1702908 (CL 04B 35/80, publ. 03/26/2014). The known method is intended to produce composite materials based on fibers, including carbon, and a matrix, which may include silicon carbide or silicon nitride, as well as various combinations of matrix phases. The method involves creating a structure of the main and auxiliary fibers, chemical deposition of the matrix material from the gas phase, several cycles of polymer impregnation-polymerization-pyrolysis. After this, an additional HOGF operation can be performed to compact the matrix. It is indicated that the strength of the composite material at high temperatures increases with increasing carbon fiber ratio. So, in the proposed embodiment of the method, in order to reduce the loss of strength of the ceramic composite material at high temperatures and to prevent from destruction of the matrix phase, the volume fraction of carbon fiber in the composite material should be approximately 70%.

The main differences and disadvantages of the proposed method include the fact that the obtained ceramic matrix composite materials (CMC) have a matrix of silicon carbide, are characterized by lower physicomechanical characteristics and oxidative stability compared to materials whose matrix was obtained in the process of CVD. In addition, the significant disadvantages of the method for producing a silicon carbide matrix include the use of volatile explosive, corrosive, poisonous starting components (MTS and methane) in the CVD process and, as a result, the formation of environmentally hazardous chlorine-containing products (HCl, SiHCl ₃ , SiCl ₄ , etc. .).

In addition, the decomposition of MTS or a mixture of MTS and methane proceeds with the formation of impurities from carbon and silicon, which impairs the strength and oxidation properties of CMCs. The processes for producing composite materials with a silicon carbide matrix from the gas phase of other chlorosilanes or silicon chloride SiCl _{4 are} characterized by the same disadvantages as the deposition process from MTS.

The technical result of patented variants of the method is to obtain ceramic composite materials for various functional purposes, possessing, depending on the application and operating conditions, the required density values in the range of 1.8 ... 2.1 g / cm ³ .

Silicon carbonitride is obtained from silazanes or silanes in accordance with the table.

Заявленный технический результат достигается в результате реализации способа получения многофункциональных керамоматричных композиционных материалов, характеризующегося тем, что в объеме пористого армирующего каркаса, выполненного из углеродных тканей или волокон в виде нитей, пучков и слоистых филаментов непрерывной или дискретной структуры, формируют керамическую матрицу из карбонитрида кремния различными методами, обусловленными вариативностью сочетаний и последовательностей реализации процесса химического осаждения из газовой фазы (ХОГФ) и процесса многократной цикловой пропитки каркаса предкерамическим полимером с последующей полимеризацией и пиролизом (ППП), При этом сочетания и последовательности реализации процессов характеризуются своим количественным вкладом и режимами технологических воздействий каждого из них в формирование керамической матрицы материалов различного функционального назначения с учетом установленных требований к уровню их физико-механических, физико-химических свойств и эксплуатационных характеристик. При этом химическое осаждение проводят в газо-вакуумных печах при температуре 500…900°C и давлении 50…500 Па, а многократную цикловую пропитку каркаса предкерамическим полимером и последующую полимеризацию и пиролиз реализуют в вакуум-компрессионых печах при температуре до 1600°C и давлении до 20 МПа.

The claimed technical result is achieved as a result of the method for producing multifunctional ceramic-matrix composite materials, characterized in that in the volume of a porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles and layered filaments of continuous or discrete structure, a ceramic matrix of silicon carbonitride is formed by various methods due to the variability of combinations and sequences of the chemical gas deposition process the new phase (HOGF) and the process of repeated cyclic impregnation of the frame with a pre-ceramic polymer followed by polymerization and pyrolysis (PPP). Moreover, combinations and sequences of processes are characterized by their quantitative contribution and the modes of technological influences of each of them in the formation of the ceramic matrix of materials of various functional purposes, taking into account established requirements for the level of their physicomechanical, physicochemical properties and operational characteristics. In this case, chemical deposition is carried out in gas-vacuum furnaces at a temperature of 500 ... 900 ° C and a pressure of 50 ... 500 Pa, and multiple cyclic impregnation of the frame with a pre-ceramic polymer and subsequent polymerization and pyrolysis are carried out in vacuum compression furnaces at temperatures up to 1600 ° C and pressure up to 20 MPa.

The above ranges are essentially the boundaries of the effective occurrence of the processes of diffusion of the pre-ceramic gas phase into the porous body and are typical for most CVD processes. An effective compaction of a porous body from the gas phase of silazanes and silanes occurs in the temperature range 500–900 ° C, depending on the chemical composition and a number of technological factors. At temperatures below 500 ° C, the rate of growth of the condensed phase is extremely low, since there is no complete decomposition of the preceramic molecule. This leads to an increase in the deposition time and to obtain a ceramic matrix with a high content of impurities. At high temperatures (above 1100-1200 ° C), the rate of the chemical reaction of the decomposition of the main component of the gas phase involved in the formation of the condensed ceramic phase becomes extremely high and makes it impossible for the molecules to penetrate into the porous frame. As a rule, low pressure values (below 10 Pa) of the CVD process lead to a significant increase in the time of compaction processes, since the compaction rate directly depends on the concentration of the main components of the gas phase. In addition, at relatively low pressures of the HOGF processes, the requirements for tightness and internal gas emission of equipment increase. High pressure values (approximately above 1000 Pa) are not used in the compaction of porous bodies for two main reasons. The first is the impossibility of organizing at high pressures the required rates of supply of the initial gas phase and removal of gaseous products of its decomposition from the porous frame, which affects the uniformity of compaction of the porous frame and the composition of the condensed phase. The second is to increase the likelihood of the process transitioning from the heterogeneous growth of the CVD process, in which the condensed phase can grow on the solid surfaces of the porous body, to the homogeneous region of the CVD process, in which the solid product is formed as a powder in the entire volume of the furnace, and the porous framework does not compact.

1. The first embodiment of the method (HOGF + 2-3 PPP cycles) is that in the volume of the porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure (2D, 2D + 1 , 3D), they form a ceramic matrix of silicon carbonitride by filling interfilament and inter-beam pores during the CVD process to a density of 1.45 ... 1.85 g / cm ³ , depending on the initial density of the frame, the volume content of the reinforcing filler and the saturation stage. Further, for the most uniform filling of the porous volume with the ceramic phase, the residual porosity is filled during the implementation of two or three SPP cycles. The result is a material with a density of at least 2.1 g / cm ³ , which is at least 95% of theoretical.

This option provides ceramic materials with high physico-mechanical, physico-chemical, thermophysical properties and operational characteristics, which provides the possibility of their use in the manufacture of critical parts and components of equipment and aircraft.

2. The second embodiment of the method (3-4 cycles of PPP + HOGF) is characterized in that in the volume of the porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure (2D, 2D + 1, 3D), a ceramic matrix is formed from silicon carbonitride by performing at least three to four SPP cycles up to a density of the composite material of 1.35 ... 1.65 g / cm ³ depending on the initial density of the carcass, the volume content of the reinforcing filler, and the saturation stage. Then, for the most uniform filling of the porous volume with the ceramic phase and increase the oxidative stability of the material, the residual and near-surface porosity is filled with ceramics formed from the gas phase (CHOF) based on a mixture of monomethylsilane with the addition of a nitrogen-containing procursor (ammonia or nitrogen) to a final density of the composite material of not more than 1 , 85 g / cm ³ .

The relationship of the initial (starting) density of the frame (1.0 ± 0.15 g / cm ³ ) with the required number of 3 or 4 cycles of the RFP to achieve the required density is shown in table 1.

The implementation of this option for producing ceramic composite materials provides the possibility of manufacturing parts and components of products that do not perceive significant mechanical loads during operation, but have a sufficiently high oxidation resistance in aggressive environments.

3. The third embodiment of the method (HOGF + 3 PPP + HOGF cycles) is that in the volume of the porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure (2D, 2D + 1 , 3D), they form a ceramic matrix of silicon carbonitride by filling interfilament and interbeam pores during gas deposition (CVD) of a mixture of monomethylsilane and ammonia (CH ₃ SiH ₃ + NH ₃ ) in a continuous stream for 40 ... 100 hours at a temperature of 500 -900 ° C to a density of 1.15 ... 1.45 g / cm ³ . Further, for the most uniform filling of the porous volume with the ceramic phase, the residual porosity is filled by performing at least three SPP cycles. As a result, a material with a density of 1.65 ... 1.85 g / cm ^{3 is} obtained, and then additional matrix compaction is carried out by the repeated process of CVD until the density of the composite material is at least 2.1 g / cm ³ .

This embodiment of the method provides high oxidative stability of the composite material in combination with sufficiently high physical and mechanical characteristics.

Chemical vapor deposition processes in all process implementations are carried out in gas-vacuum furnaces at a temperature of 500 ... 900 ° C and a pressure of 50 ... 500 Pa.

To ensure the regimes of the formation of the ceramic matrix by liquid-phase methods and gaseous media of the required composition with a temperature in the chemical reactor up to 900 ° C and a pressure of 5 to 1 × 10 ⁷ Pa, a special vacuum compression shaft resistance furnace with programmed temperature control is used. The furnace is designed to process materials in vacuum or under pressure up to 20 MPa at temperatures up to 1600 ° C and has the following technical characteristics: heating rate up to 400 ° C / hour; exposure time at a given temperature up to 5 hours; leakage into the gas-vacuum circuit is not more than 5 · 10 ^-4 Pa × m ³ / s; temperature uniformity in the isothermal zone ± 5 ° C.

Silicon carbonitride in all embodiments of the process is obtained from silazane, or silane, or a mixture of monomethylsilane and ammonia. In this case, hydrocarbon silanes are used as silane: methylsilane, ethylsilane; as silazanes, polysilazanes: disilazane, methylsilazane, ethylsilazane or cyclosilazanes: trisilazane, tetrasilazane, pentasilazane or Si, N-methylcyclosilazane and Si, N-ethylcyclosilazane.

Examples of the method according to the proposed options for producing multifunctional ceramic composite materials.

1. The method of producing a ceramic composite material according to option 1 (HOGF + 2-3 PPP cycles), which provides the highest functional characteristics of products with respect to their mechanical strength, heat resistance and oxidative stability, is realized as a result of technological actions in two stages. At the first stage, the compaction of a carbon - carbon porous reinforcing framework of a continuous structure (2D + 1) (density of the order of 1.05 g / cm ³ , open porosity of the order of 32%), made on the basis of UT-900-3K-240 ED fabric, phenolic coke resin and partially compacted with pyrolytic carbon from the gas phase of methane, is carried out in the process of HOGF, which provides the greatest contribution to filling the porous volume of the matrix. The duration of the CVD process is not more than 550 hours and is carried out at a temperature of 500-900 ° C and a pressure of 50-500 Pa. The density of the composite material increases to about 1.80 g / cm ³ and the open porosity decreases to 8%. At the second stage, the matrix is further compacted using methylsilazane as a result of three PPP cycles, which is no more than 24 hours of technological time. Thus, the total technological time for the formation of the silicon nitride matrix did not exceed 574 hours, and the final density of the composite material increased to 2.10 g / cm ³ with an open porosity of about 1.5%.

2. To obtain a ceramic composite material according to option 2 (3-4 cycles of PPP + HOGF) used in the manufacture of products less mechanically loaded and working in oxidizing environments, sealing a porous reinforcing framework of a continuous structure 2D (density of the order of 1.05 g / cm ³ , open porosity of the order of 32%), formed on the basis of UT-900-3K-240-ED fabric and phenolic resin coke, is carried out in two stages.

Initially, silicon carbonitride is formed on a porous reinforcing framework by triple cyclic impregnation with a pre-ceramic polymer (oligoorganosilazane) followed by its polymerization and pyrolysis (SPP) in a nitrogen-containing medium at a temperature of more than 600 ° C and a pressure of up to 0.8 MPa. At the same time, the technological time of the process with 4 cycles of IFR is approximately 32 hours. The density of the material is about 1.50 g / cm ³ . The final densification of the matrix is carried out by chemical vapor deposition of monomethylsilane with ammonia (CHOF) in the temperature range of 500-900 ° C and a pressure of 50-500 Pa for about 70 hours until the density of the composite material is about 1.75 g / cm ³ and open porosity about 1.5%. Tensile and compressive strengths of such a ceramic composite material are at least 100 MPa and 140 MPa, respectively; and the limit of proportionality is not less than 35 MPa. The total technological time for the formation of the silicon nitride matrix was 132 hours; The maximum compaction time can reach 190 hours.

3. To obtain a ceramic composite material with improved functional characteristics according to option 3 (HOGF + 3 PPP + HOGF cycles), a carbon – carbon porous reinforcing frame of a continuous structure 2D + 1 (density of the order of 1.1 g / cm ³ , open porosity of the order of 30 %), made on the basis of UT-900-3K-240-ED fabric, phenolic resin coke and partially densified with pyrolytic carbon from the methane gas phase. The compaction of the porous framework with silicon carbonitride was carried out as a result of technological actions in three stages. Initially, silicon carbonitride was precipitated from a gas mixture of monomethylsilane and ammonia (CH ₃ SiH ₃ + NH ₃ ) in a continuous stream in the temperature range of 500-900 ° C and a pressure of 50-500 Pa for about 100 hours. The process of chemical vapor deposition (CVD) is carried out until the predominant closure of interfilament porosity and provides a density of about 1.35 g / cm ³ . At the second stage, three cycles of impregnation with a pre-ceramic polymer (oligoorganosilazane) were carried out, followed by polymerization and pyrolysis in a nitrogen-containing medium at a temperature of more than 600 ° C and a pressure of up to 0.8 MPa. At this stage, the technological time of the process was 24 hours. The density of the material increased to about 1.75 g / cm ³ . In the third stage, to close the near-surface porosity, a chemical vapor deposition of a mixture of monomethylsilane and ammonia was carried out in a gas temperature range of 500–900 ° C and a pressure of 50–500 Pa for 60 hours. The final density of the ceramic composite material was 2.1 g / cm ³ with an open porosity of less than 1%.

The implementation of this embodiment of obtaining CMC allows to reduce the technological time by 20-25% in comparison with the process of obtaining a ceramic matrix only by chemical vapor deposition (CVD). The tensile and compressive strengths of such a material are at least 130 MPa and 170 MPa, respectively, and the proportionality limit is 42 MPa.

After testing in air 120 cycles (heating to 1050 ° C in 40 seconds - holding for 20 minutes - cooling to 20 ° C within 150 ... 200 seconds), the decrease in tensile strength is not more than 4.5%; and the limit of proportionality is 4.7%. This is more than 2 times the oxidation resistance of a traditional C / SiC material and more than 20% physical and mechanical properties of C / SiC type CMs after similar tests.

When operating up to 1050 ° C, the degradation of material properties will be less than in the presented example. At temperatures above 1050 ° C - respectively more. In this case, the tendency in the advantage of a composite material with a SiCN matrix up to 1400 ° C compared with a composite material with a SiC matrix will continue.

The total technological time for the formation of the silicon nitride matrix was 324 hours; The maximum compaction time can reach 374 hours.

Claims (10)

1. The method of obtaining multifunctional ceramic-matrix composite materials, which consists in the fact that in the volume of a porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure, a ceramic matrix of silicon carbonitride is formed by filling interfilament and inter-beam then in the process of chemical deposition from the gas phase to a density of 1.55 ... 1.85 g / cm ³ , and then for the most uniform filling of the porous volume of ceramic f The residual porosity is filled in by means of two or three cycles of impregnation, polymerization and pyrolysis (PPP), the result is a material with a density of at least 2.1 g / cm ³ , while chemical deposition is carried out in gas-vacuum furnaces at a temperature of 500 ... 900 ° C and a pressure of 50 ... 500 Pa. 2. The method according to p. 1, which consists in the fact that the ceramic matrix of silicon carbonitride is obtained from silazane and silane. 3. The method according to p. 2, characterized in that the silane used is hydrocarbon silanes: methylsilane, ethylsilane; as silazanes, polysilazanes: disilazane, methylsilazane, ethylsilazane or cyclosilazanes: trisilazane, tetrasilazane, pentasilazane or Si, N-methylcyclosilazane and Si, N-ethylcyclosilazane. 4. The method according to p. 1, characterized in that the impregnation process followed by polymerization and pyrolysis is carried out in a vacuum compression shaft resistance furnace at temperatures up to 1600 ° C in gaseous media with a pressure of up to 20 MPa. 5. A method for producing multifunctional ceramic-matrix composite materials, which consists in the fact that in the volume of a porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure, a ceramic matrix of silicon carbonitride is formed by the implementation of three or four cycles of the impregnation process with subsequent polymerization and pyrolysis to a density of the composite material of 1.35 ... 1.65 g / cm ³ depending on the initial density of the frame, volume a lot of reinforcing filler content and saturation stage, and then for the most uniform filling of the porous volume with a ceramic phase, the residual porosity is filled with ceramics formed on the basis of a mixture of monomethylsilane with the addition of a nitrogen-containing procursor during chemical deposition from the gas phase to a final density of the composite material of at least 1.85 g / cm ³ , while chemical deposition is carried out in gas-vacuum furnaces at a temperature of 500 ... 900 ° C and a pressure of 50 ... 500 Pa. 6. The method according to p. 5, which consists in the fact that the ceramic matrix of silicon carbonitride is obtained from silazane and a mixture of monomethylsilane and ammonia. 7. The method according to claim 6, characterized in that polysilazanes are used as silazanes: disilazane, methylsilazane, ethylsilazane or cyclosilazanes: trisilazane, tetrasilazane, pentasilazane or Si, N-methylcyclosilazane and Si, N-ethylcyclosilazane. 8. A method of obtaining multifunctional ceramic-matrix composite materials, which consists in the fact that in the volume of a porous reinforcing frame made of carbon fabrics or fibers in the form of threads, bundles or layered filaments of continuous or discrete structure, a ceramic matrix of silicon carbonitride is formed by filling interfilament and inter-beam then in the process of chemical vapor deposition for 40 ... 100 hours to a density of 1.15 ... 1.45 g / cm ^3, then for the most uniform filling of porous EMA residual porosity of the ceramic phase is filled by performing three cycles of the impregnation process, followed by polymerization and pyrolysis to yield material with a density of 1.65 ... 1.85 g / cm ^3, and then carried out further densification of the matrix in the process of chemical deposition from the gas phase into 40 ... 100 hours to a density of composite material of at least 2.1 g / cm ³ , while chemical deposition is carried out in gas-vacuum furnaces at a temperature of 500 ... 900 ° C and a pressure of 50 ... 500 Pa. 9. The method of claim 8, wherein the ceramic matrix is made of silicon carbonitride from silazane and silane or a mixture of monomethylsilane and ammonia. 10. The method according to p. 8, characterized in that as the silane using hydrocarbon silanes: methylsilane, ethylsilane; as silazanes, polysilazanes: disilazane, methylsilazane, ethylsilazane or cyclosilazanes: trisilazane, tetrasilazane, pentasilazane or Si, N-methylcyclosilazane and Si, N-ethylcyclosilazane.