CN115515914B - Method for manufacturing ceramic matrix composite material containing specific interface phase - Google Patents

Abstract

A method of manufacturing a composite material comprising a fibre reinforcement and a ceramic matrix, said matrix comprising fibres coated with a thin layer called interface phase, characterized in that said method comprises: -forming an interphase on the fibers by deposition or chemical infiltration in two uninterrupted continuous steps, wherein the main manufacturing step is characterized in that during at least 80% of the time of depositing the complete interphase, a mixture consisting of the following gases is used: on the one hand, at least ammonia and hydrogen, and on the other hand, boron trichloride and carbonyl dichloride, the latter having a concentration of 1% to about 5% with respect to the atomic percentage of boron trichloride, the final total thickness of the interfacial phase being 0.1 to 1 μm; -after coating the interfacial phase on the fibers, subjecting said interfacial phase coated fibers to a heat treatment, without exposure to an oxidizing atmosphere, said heat treatment being carried out at a temperature equal to or higher than about 1100 ℃; the manufacture of the composite is then achieved by including the fibres coated with the interfacial phase in a matrix made at least in large part of ceramic. The relatively inexpensive method can be used to produce high performance ceramic matrix composites.

Description

Method for manufacturing ceramic matrix composite material containing specific interface phase

The present invention relates to ceramic matrix composites, and more particularly to composites having a fibrous reinforcement embedded in a matrix, wherein at least one thin layer, the so-called interphase, separates the fibers from the matrix.

Ceramic matrix composites, hereinafter CMC, are known lightweight materials for use in the manufacture of components exposed to conditions such as in aerospace applications or other fields (e.g., industrial turbines). The material is reinforced with fibers (including carbon fibers and ceramic fibers) and densified by a ceramic matrix. At least one continuous layer or interfacial phase between the fibers and the matrix can tailor the bond strength between the two components of the CMC. CMC is a material that is mechanically resistant in terms of bending, traction and impact resistance, and in particular is capable of retaining its mechanical properties over a wide temperature range from 500 to over 1600 ℃. In the high temperature range, a thermal and/or environmental barrier is used to improve its resistance to ambient gases under the thermo-mechanical conditions of use.

The present invention relates generally to ceramic matrix composites in which the interfacial phase is deposited from the vapor phase by Chemical Vapor Deposition (CVD) or Chemical Vapor Infiltration (CVI) methods. In order to obtain better oxidation resistance than high temperature carbon (pyrocarbon), the interphase is generally at least partially composed of a layer of boron nitride. The interfacial phase is deposited by CVD onto a yarn consisting of hundreds to thousands of reinforcing fibers, typically by a continuous process, which is passed through a chemical reaction zone at a certain velocity, thereby being coated with a layer having a certain thickness, as described for example in us patent 2002066409 A1. The technique described close to CVD, i.e. the technique that has to form a coating of controlled thickness and structure on all the fibres (up to the yarn core), is more precisely referred to herein as "forced CVD/CVI", because the direction of the gas phase has to be directed towards the yarn, in order to perform satisfactory deposition by gas phase infiltration, and mass transfer by forced convection and diffusion to the surface of all the fibres within the yarn. The mixing technique is characterized by a sufficiently fast mass transfer to the fibers that it makes it possible to use relatively high temperatures of 1100 to 1500 ℃. The forced CVD/CVI type process may also be used to continuously deposit layers, including boron nitride layers, on fibers that constitute a thin fabric made by weaving, braiding or knitting yarns, such as described in us patent 2016229758, where vapor infiltration is performed by forced convection and diffusion into the fabric. According to the infiltration process in M.Lepamoux (university of Orleans, 1995) and L.Vandenbulcke and M.Lepamoux (Journal de Physique IV,1995, 05 (C5), pages C5-735-C5-751, pages jpa-00253950), which has been optimized, the boron nitride interface phase is also deposited in a three-dimensional preform by isothermal chemical infiltration (ICVI) from the gas phase, as described in patents WO 9823555 and WO 2014049221, made from a three-dimensional weave of yarns or a stack of woven or woven layers of woven layers. In the ICVI process, the vapor phase is continuously circulated between the inlet and outlet of the deposition reactor. A Pulsed (PCVI) CVI process, such as that described in patent WO 9823555, is also used, in which the interfacial phase is deposited in successive cycles. Each cycle involves introducing a reactive gas into the deposition reactor, maintaining the gas phase during deposition, and then evacuating by pumping or flushing with an inert gas. In ICVI and PCVI, the deposition temperature is much lower than the forced CVD/CVI, typically 650 to 900 ℃.

The expensive starting materials (e.g., fibers) that make up the composite, as well as the expensive processes used in the method of making the interphase and the matrix, make the composite useful for high value-added applications. Even so, any cost reduction of the assembly or process is important.

The invention aims to reduce the manufacturing cost and optimize the interfacial phase of the ceramic matrix composite material. The aim is to produce a CMC with high performance, at least equal to or better than that obtained by depositing boron nitride on fibres using previous methods, while reducing the manufacturing costs. Part of the high manufacturing cost is due to the high gas cost for manufacturing the interfacial phase, particularly boron trichloride, which is most commonly used for depositing boron nitride.

The preparation method of the commercial boron trichloride comprises the following steps: chlorine is reacted with boron carbide in a molten borate or with boron carbide in a fluidized bed with a transition metal chloride catalyst or with boron oxide in the presence of carbon. In all cases, boron trichloride BCl ₃ Are subjected to carbonyl dichloride (COCl) ₂ ) Is a strong contamination of synthetic commercial BCl ₃ One major drawback and additional cost of (1) is due to commercial BCl ₃ It is necessary to carry out purification. The two molecules are indeed difficult to separate, in particular by fractionation, because of the two speciesThe vapor pressure of the mass varies very closely with temperature. Separation of the two, e.g. by COCl ₂ Thermal or photochemical conversion to CO and Cl ₂ Followed by fractionation, which results in the synthesis of commercial BCl ₃ The cost of (2) is greatly increased. On the other hand, volatile gaseous impurities having boiling points well below 0deg.C, e.g. Cl ₂ And HCl, can be easily separated. The product resulting from the simple separation is not a commercially available BCl ₃ But rather BCl ₃ And COCl as a main impurity ₂ (up to about 5% by atomic percent). Commercial BCl purified, chemically pure grade (CP) ₃ Contains only 0.5% of impurities, but has a purity far higher than 99.5%, i.e. equal to or higher than 99.99% of BCl ₃ Can be used in particular in the electronics field, the so-called technical grade BCl ₃ Contains 1% of impurities (organic small molecule biological activity database (Pubchem): boron trichloride/BCl ₃ In (Impurities in Boron trichloride/BCl 3), 1978, sections 7.4-7.5). BCl (binary coded decimal) ₃ All BCl provided by manufacturer and supplier ₃ The purity of (2) varies from 99% to 99.999%, 99% being the lowest purity obtainable under the name boron trichloride.

In the above patents, boron nitride is most often deposited from a mixture of boron trichloride, ammonia and hydrogen, but none of them specifies the purity of the gas used, in particular the purity of the boron trichloride used. None of the above patents describe the presence of at least one other gas in such large amounts that it is not possible to use the unique name boron trichloride as a reactive or synthesis gas for boron compounds such as boron nitride. The name of the chemical is actually specific to technical grade boron trichloride having a purity of at least 99%, whereas the purity of boron trichloride used as chemically pure reagent, i.e. "reagent grade" in its U.S. name, is 99.5% (small organic molecule biological activity database (Pubchem): boron trichloride/impurities in boron trichloride (Impurities in Boron trichloride/BCl 3), 1978, sections 7.4-7.5). Thus, in patent EP 2548855A1 and US 8 986 845 "reagent grade" purity BCl is used ₃ For use in the production of boron trichloride/hydrogen mixturesA boron element layer infiltrated in the CMC matrix is fabricated. Once the boron trichloride with the purity lower than 99% is used, it is no longer boron trichloride but rather boron trichloride with its main impurity COCl ₂ Which mixture will change the properties of the deposited solid. Therefore, as long as hydrogen and BCl having a purity of less than 99% are used ₃ Not obtaining a boron layer but B [ C ] of different structure]A patterned layer, as shown in patent WO 2018220296, wherein the carbon concentration in the deposited solid is well above 0.4%.

Unlike the conditions of deposition of the boron nitride interface phase described in the above patents and publications, the present invention uses mainly chemical deposition or infiltration of the interface phase from a gaseous mixture of at least ammonia and hydrogen, to which a mixture of boron trichloride and carbonyl dichloride is added, the latter in atomic percent having a concentration of up to about 5% relative to that of boron trichloride, when said BCl ₃ When reduced by hydrogen reagent alone, the mixture of boron trichloride and the major impurities formed during its synthesis thus contains sufficient carbon to render B [ C ]]The type deposit contains a large amount of carbon (0.4 to 8% in atomic percent). Thus, COCl ₂ Play an important role in the deposition process used in combination with boron trichloride.

The invention therefore relates to the production of composite materials with a ceramic matrix, the interfacial phase of which is largely composed of BCl ₃ +COCl ₂ +NH ₃ +H ₂ Is made of a mixture of (1) wherein COCl ₂ Without slave BCl ₃ This is in contrast to previous processes which used a reagent named boron trichloride which had to be purified to produce boron nitride, which contained less than 1% COCl ₂ Typically in an amount of 0.05%. For deposition/infiltration of BN, M.Leparoux (university of Orleans paper, 1995) uses BCl ₃ +NH ₃ +H ₂ Wherein the purity of all gases is 99.995%.

The gas mixture used here causes a negative effect of impurities and an initial adverse interaction with the reinforcing fibres of the composite material, compared to the results obtained with such purity and with any reagent called boron trichloride. The method of the invention thus uses in particular two interfacial phase manufacturing steps, which are carried out in a continuous sequence.

The object of the present invention is therefore a method for manufacturing a composite material comprising a matrix of ceramic and fibre reinforcement, the matrix comprising fibres coated with a thin layer called interface phase, characterized in that it comprises:

-in two consecutive steps without interruption, the manufacture of the interface phase being intended to form a thin layer on the fibers by chemical deposition or chemical infiltration from a gaseous phase consisting, in a first manufacturing step, of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9% and boron trichloride with a purity equal to or greater than 99%, then in a second manufacturing step, of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9%, boron trichloride with a purity less than 99% and carbonyl dichloride with an atomic percentage concentration of greater than 1% with respect to boron trichloride, the duration of the first step being less than or equal to 20% of the total duration of the manufacture of the interface phase, the final thickness of the interface phase being between 0.1 and 1 μm.

-after coating the interfacial phase on the fibers, subjecting said interfacial phase coated fibers to a heat treatment, without exposure to an oxidizing atmosphere, at a temperature equal to or higher than about 1100 ℃ for a duration of less than 4 hours;

-subsequently effecting the manufacture of a composite material by including the interfacial phase coated fibers in said matrix.

Preferably, in the first step of chemical deposition or chemical infiltration from the gas phase, the interfacial phase is produced using boron trichloride having a purity equal to or greater than 99.5%. In the second step of the production of the interfacial phase, the production method of the present invention is characterized in that boron trichloride is produced only from highly volatile impurities (essentially Cl) having a boiling point below 0 DEG C ₂ And HCl).

During the synthesis of boron trichloride, impurities other than carbonyl dichloride, e.g. silicon tetrachloride, siCl, are present ₄ Particularly when the synthesis of boron trichloride is carried out in a silica reactor. The invention further comprises a method of manufacture wherein a silicon precursor is added to the gaseous mixture during at least part or all of one of the two chemical deposition or infiltration steps, said precursor being selected from the group consisting of: silane, and one of silicon chloride and methyltrichlorosilane. This addition allows the deposition of an interfacial phase comprising at least one Si-B-N ternary based layer. Preferably, the concentration of the gaseous silicon precursor is adjusted to obtain an atomic percent concentration of silicon in this layer of the interface phase of at least 20%.

The present invention relates to the use of various fiber reinforced ceramic matrix composites. The fibers used are carbon, alumina, mullite or silicon carbide fibers. In the latter case, the silicon carbide fiber contains carbon and silicon as main elements, and among other impurities, the concentration of oxygen is 0.05 to 14% in atomic percent. As is well known to the expert, the fibres have very different thermal stabilities, depending on their composition and structure. The fibers will be included in a composite material that is applied to a temperature range of 550 to 1600 c, depending on their thermal stability.

The process of the invention uses fibres of various diameters, most commonly 7 to 15 μm. The fibers are not used alone, but are organized to form a yarn containing hundreds to thousands of fibers. The yarns may be coated directly from the interfacial phase by using the method of the present invention. The yarns may also be organized into a predominantly elongated, thin fabric having two directions (2D), the fabric being made by weaving, braiding, or knitting the yarns. According to the method of the invention, the 2D fabric may also be coated with an interfacial phase. In both cases, the interfacial phase is produced on one or more parallel arranged yarns or on a 2D fabric by forced chemical deposition/infiltration from the gas phase (forced CVD/CVI) so that all the fibers of the yarn or fabric have the same interfacial phase thickness, or at least a similar thickness and similar structure. In order to obtain such a result, the mass transfer to all the areas to be coated must be sufficiently fast with respect to the chemical kinetics of the surface of said areas. In order to obtain such a result, which has been known for a long time (l.vandenbulcke: j. Electrochem. Soc.124 (12), 1977, pages 1931-1937 and 1937-1942), the direction of flow of the vapor phase in the deposition chamber according to the process of the present invention is at least more than about 20 degrees from the main direction of the yarn or the plane of the fabric if not exactly perpendicular to the yarn or the fabric as described in the publications cited above. The interfacial phase deposition temperature and vapor pressure also play an important role in the mass transfer conditions and deposition kinetics of the vapor phase to each fiber. The forced CVD/CVI deposition conditions allow the use of relatively high deposition/infiltration temperatures while maintaining good interphase thickness uniformity across each fiber. Thus, the process of the present invention uses interfacial phase fabrication methods on 2D yarns and fabrics by chemical deposition/infiltration at temperatures equal to or greater than 1100 ℃ and pressures from 0.2 to 10 kPa.

The interfacial phase fabrication in the deposition chamber is performed on one or more yarns or on a stationary 2D fabric. The manufacture can also be carried out according to the method of the invention on one or more yarns or on 2D fabrics, with a passage speed of 2 to 500 cm per minute. In the last case, the implementation of the method, although more complex, allows to coat greater amounts of fibers without having to interrupt the process.

In a variant of the method for manufacturing a composite according to the invention, when the interfacial phase is manufactured by forced CVD/CVI on one or more yarns or 2D fabrics, there is no need for heat treatment of the fibers coated with the interfacial phase in case the deposition/infiltration temperature is sufficiently high (temperature greater than 1100 ℃, preferably equal to or greater than about 1250 ℃) to ensure good interfacial phase stability. The system for carrying out the method comprises two interfacial phase manufacturing chambers through which the yarn or fabric passes. Systems that use multiple sequential chambers for deposition operations are well known to those of ordinary skill in the art.

The invention therefore comprises a method for manufacturing a composite material comprising a matrix of ceramic and fibre reinforcement, the matrix comprising fibres coated with a thin layer called interface phase, characterized in that it comprises:

-in two consecutive steps without interruption, the manufacture of the interface phase being made in order to form a thin layer on the fibers by chemical deposition or chemical infiltration from a gaseous phase consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9% and boron trichloride with a purity equal to or greater than 99%, in a first manufacturing step, then in a second manufacturing step, the gaseous phase consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9%, boron trichloride with a purity less than 99% and carbonyl dichloride with an atomic percentage concentration of greater than 1% with respect to boron trichloride, the duration of the first step being less than 20% of the total duration of the manufacture of the interface phase, the final thickness of the interface phase being between 0.1 and 1 μm, the manufacture being carried out on one or more yarns or 2D fabrics according to the forced CVD/CVI method at a temperature greater than 1100 ℃.

-subsequently effecting the manufacture of a composite material by including the interfacial phase coated fibers in said matrix.

The above method comprises only two deposition chambers, and does not comprise a heat treatment chamber when the deposition temperature is higher than 1100 ℃, preferably in the highest temperature range, i.e. equal to or higher than about 1250 ℃.

In another version of the method, according to well known methods, in particular in the electronics field, the system used comprises winding the yarn or fabric on a drum, causing it to be evacuated in a controlled atmosphere, and subsequently transporting and placing it in a heat treatment chamber.

In a variant of the forced CVD/CVI process mainly for fibres with the highest oxygen content, the object of the present invention is a process characterized in that the duration of the first step is zero, i.e. the interfacial phase is entirely made of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or higher than 99.9%, boron trichloride with a purity lower than 99% and carbonyl dichloride with a concentration higher than 1% relative to boron trichloride, the final thickness of the interfacial phase being between 0.1 and 1 μm. The interfacial phase is then fabricated in a single deposition/infiltration chamber and thermal processing chamber.

The invention therefore comprises a method for manufacturing a composite material comprising a matrix of ceramic and fibre reinforcement, the matrix comprising fibres coated with a thin layer called interface phase, characterized in that it comprises:

-the manufacture of an interface phase for forming a thin layer on the fibres by chemical deposition or chemical infiltration from a gaseous phase consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9%, boron trichloride with a purity less than 99% and carbonyl dichloride with a concentration greater than 1% relative to the atomic percentage of boron trichloride, the thickness of the interface phase being between 0.1 and 1 μm.

After the interfacial phase has been applied to the fibers, the interfacial phase coated fibers are heat treated at a temperature equal to or greater than about 1100 ℃ for a duration of less than 4 hours without exposure to an oxidizing atmosphere,

-subsequently effecting the manufacture of a composite material by including the interfacial phase coated fibers in said matrix.

As can be seen, the process of the present invention uses fibers of various diameters, most commonly 7 to 15 μm. The fibrous structure forms a yarn containing several hundred to several thousand fibers. In the method of the invention described above, the yarn or the 2D fabric made of yarn is coated with the interfacial phase by forced CVD/CVI.

The yarns consisting of fibres are also used to construct a three-dimensional fibrous preform made of a three-dimensional weave of yarns or a stack of woven or woven layers of woven layers having a more or less strong reinforcement (strong reinforcement) in a third dimension, the woven layers being stacked by a clamping means consisting of a porous solid material that allows the passage of gas through the fibres. The tools used as shapers (formers) for fiber preforms are well known to those of ordinary skill in the art.

For the three-dimensional fiber preform, the interfacial phase manufacturing process is a continuous gas phase chemical infiltration process (CVI) or a pulse gas phase chemical infiltration Process (PCVI) performed from a gas phase at a temperature of 650 to 900 ℃ and a pressure of 0.1 to 5kPa, and a gas mixture composed of at least ammonia gas and hydrogen gas having a purity of 99.9% or more, boron trichloride having a purity of less than 99%, and carbonyl dichloride having an atomic percentage concentration of more than 1% with respect to boron trichloride is always used for at least 80% of the interfacial manufacturing time.

The object of the present invention is therefore a method for manufacturing a composite material comprising a matrix of ceramic and fibre reinforcement, the matrix comprising fibres coated with a thin layer called interface phase, characterized in that it comprises:

-carrying out the manufacture of the interfacial phase from a gas phase consisting of a gas mixture consisting of at least ammonia and hydrogen with a purity equal to or higher than 99.9% and boron trichloride with a purity equal to or higher than 99% in a first manufacturing step, then of at least ammonia and hydrogen with a purity equal to or higher than 99.9% in a second manufacturing step, of boron trichloride with a purity less than 99% and a concentration of more than 1% by atomic percentage relative to boron trichloride, the duration of the first step being less than or equal to 20% of the total duration of the manufacture of the interfacial layer, the final thickness being between 0.1 and 1 μm.

-after coating the interfacial phase on the fibers, subjecting said interfacial phase coated fibers to a heat treatment, without exposure to an oxidizing atmosphere, at a temperature equal to or higher than about 1100 ℃ for a duration of less than 4 hours;

-subsequently effecting the manufacture of a composite material by including the interfacial phase coated fibers in said matrix.

In the case of performing the CVI or PCVI method on a fiber preform, after heat treatment of the interfacial phase coated fiber, the gripping tool is most often used to consolidate (con solid) the preform from a first matrix layer manufactured by CVI. Densification of the substrate then takes place after the preform has been removed from its gripping tool.

Of course, the variants of the invention described above for the forced CVD/CVI process are also applicable to the CVI and PCVI processes, in addition to variants that do not use heat treatment after infiltration of the interfacial phase.

In a variant of the CVI/PCVI process for three-dimensional fiber preforms, the object of the present invention is a process characterized in that the first step has a zero duration, i.e. the manufacture of the interphase completely uses a gaseous mixture consisting at least of ammonia and hydrogen with a purity equal to or greater than 99.9%, boron trichloride with a purity less than 99% and carbonyl dichloride with an atomic percentage concentration of greater than 1% with respect to boron trichloride, the final interphase having a thickness ranging from 0.1 to 1 μm.

In addition to forcing CVD/CVI at a temperature equal to or greater than 1250 ℃, the method of the present invention, after coating the fibers with the interfacial phase, subjects the fibers coated with the interfacial phase to a heat treatment at a temperature of at least 1100 ℃ for a time of less than or equal to 4 hours, preferably less than or equal to 2 hours, without exposure to an oxidizing atmosphere. The selected treatment temperature depends on the thermal stability of the fibers. For silicon carbide fibers, such as Nicalon of Nippon Carbon ^TM The shaped fibers, depending on the type of fiber, maintain good thermal stability at about 1100 ℃ to 1600 ℃. The heat treatment is carried out taking into account said temperature and therefore does not significantly alter the inherent mechanical properties of the fiber. Thus, the process of the present invention treats the interfacial phase coated fibers at a temperature of about 1100 ℃ to 1600 ℃. The heat treatment is preferably carried out under an inert atmosphere and at a temperature and for a time at which the nominal intrinsic modulus of elasticity of the fibers provided by the manufacturer does not vary by more than 5%. The heat treatment is performed in a gas atmosphere such as a rare gas (preferably argon) or nitrogen.

The method of manufacturing a composite material according to the present invention is further performed by embedding fibers coated with an interface phase deposited or heat treated at a high temperature in a matrix. The matrix is composed of at least one material selected from the group consisting of oxides, carbides, nitrides and silicides, or a combination of materials derived from at least one of them. Among them, silicon carbide is widely used as a material constituting the matrix.

According to various techniques known to those of ordinary skill in the art, fibers coated with an interphase deposited or heat treated at high temperature are at least partially embedded by:

-Chemical Vapor Infiltration (CVI) and/or

Impregnation with at least one polymer of a ceramic precursor, subsequent pyrolysis and/or

-introducing carbon and/or ceramic powder between the fibres coated with the interfacial phase and infiltrating the silicon-based metal in molten state to form silicon carbide.

For example, a third method called "melt infiltration" or MI is described in particular in patent US4,889,686 (a) and US5,015,540 (a).

The method of manufacturing a composite material according to the present invention further comprises a matrix material that allows the matrix to self-repair when the interior of the matrix is exposed to an oxidizing atmosphere through cracks in the joining surfaces, whether it originates from the manufacture or use of the composite material. In said case, the matrix consists of layers of different nature, comprising silicon carbide and at least one carbide from the binary or ternary systems of boron-carbon, as described for example in patent US5246736 and WO 2018220296. In the present invention, the layers are penetrated by CVI and elemental boron is provided in all of the B-C or Si-B-C layers by a gas phase preferably containing boron trichloride having a purity of less than 99%.

The method of manufacturing a composite material according to the invention comprises a matrix of fibre reinforcement and mainly composed of ceramic, wherein said matrix, internally comprising fibres coated with a thin layer called interface phase, may comprise a multi-directional reinforcement. The composite material comprises the following reinforcements: the fiber reinforcement constituting the elongated yarns in one main reinforcement direction (1D composite), or the yarn reinforcement constituting the fabric with two main reinforcement directions (2D composite), or the yarn reinforcement additionally comprising partial reinforcement in the third direction (2.5D composite), or the yarn reinforcement constituting reinforcement in the nth direction, where N is not less than 3.

Further features and advantages of the invention will be more clearly demonstrated from the description of the drawings and the following examples.

Fig. 1 is a schematic cross-sectional view of a composite material made in accordance with the present invention reinforced in two directions. The composite material (1) comprises a fibrous reinforcement (10) and a matrix (11) consisting essentially of ceramic, the fibers being coated with a thin layer called interface phase (12), the fibers being contained in the matrix.

For example, U.S. Pat. nos. 6,630,029 and 2016229758 provide examples of apparatus for implementing a forced CVD/CVI interfacial phase manufacturing process on a yarn or fabric. According to an early technique of depositing amorphous boron on tungsten filaments to form amorphous boron filaments having a diameter of about 100 μm, the yarn or fabric is passed through a deposition/infiltration chamber. Another type of forced CVD/CVI device based on similar scientific principles but in stationary mode is herein referred to as a variant of the CVI device described in detail below. It can be seen that it combines mass transfer by forced convection (upward in nature) with mass transfer by natural rising convection and diffusion of gaseous reactants under reduced pressure.

Fig. 2 is an exemplary schematic diagram of a CVI device for manufacturing an interfacial phase and a substrate. This involves infiltration of the interfacial phase into the fiber preform, which is embedded in its clamping tool. Hydrogen is filled in a gas cylinder (20), BCl ₃ Is filled in a gas bottle (21), COCl ₂ Is arranged in a gas cylinder (22). From the two gases BCl ₃ And COCl ₂ The mixture formed, the latter content being greater than with respect to BCl ₃ The mixture is a mixture resulting from the synthesis of boron trichloride, here artificially duplicated by mixing two pure gases. Ammonia is contained in a cylinder (23) and is delivered at a controlled flow rate through pipes, each having a shut-off valve (24), (25), (26) and (27) and a mass flow meter (28), (29), (30) and (31). The gas mixture of controlled composition is then introduced into a deposition reactor (33) through a conduit (32). It is placed in a chamber (34) in which the atmosphere can be evacuated and controlled. Inside the reactor (33), there are one or more fibrous preforms (36) of interface phase to be coated within a susceptor (35) of thermally conductive material, such as graphite coated with silicon carbide. The thermal sensor (37) is connected to the high frequency generatorA susceptor (38), a high frequency generator (38) heating the susceptor and the fibrous web to be interfacially infiltrated. The thermocouple (39) allows driving the generator with the aid of a temperature controller (40) so that the susceptor and the fibrous preform to be infiltrated reach the desired temperature. A pump (41) is used to create an initial vacuum in the chamber (34) and then the pressure in the chamber is maintained at a desired value by a pressure sensor and control valve (42) secured to the chamber. A trap (43) located before the pump protects the pump and control system from corrosive halogenated gases. The remaining gas lines allow the entire process to proceed. Thus, the heat treatment is carried out under a controlled atmosphere, such as argon introduced from a gas source (44) having a valve (45) and a flow meter (46). The initial consolidated deposit of the fibrous preform, for example with a silicon carbide layer, may be made of a mixture of hydrogen contained in a bottle (20) and methyltrichlorosilane from an additional bottle, the accessories of which are not shown here.

After consolidation of the fiber preform, for example, after removal of the fiber preform from its clamping tool, the matrix may be further densified with silicon carbide in the same reactor.

The ease of implementation, versatility of the method and variants thereof, and advantages of the method are demonstrated by the more specific examples.

In example 1, the method of manufacturing a composite material according to the present invention uses a fiber preform made of a fabric and reinforced in two directions (2D). Hi-Nicalon produced by Nippon Carbon ^TM The fiber composition, which has been subjected to a specific treatment, removes the natural oxides on its surface according to well known methods. The preform is placed in a clamping tool and the whole set is introduced into the deposition reactor (33) of fig. 2 to deposit the interphase by CVI. The first step used a gas mixture consisting of ammonia and hydrogen with a purity of 99.95% and boron trichloride with a purity of 99.95%, and permeated the 0.04 μm interfacial layer at a temperature of 700 ℃ and a pressure of 1.3 kPa. A second step of using a gas mixture composed of ammonia gas and hydrogen gas having a purity of 99.95%, boron trichloride having a purity of 99.95% and carbonyl dichloride having a concentration of 2.5% relative to the boron trichloride under the same temperature and pressure conditions to Final interface thickness of 0.2 μm. The boron trichloride plus carbonyl dichloride mixture used herein corresponds to the synthesis of only the volatile materials such as Cl ₂ And boron trichloride purified in HCl.

After flushing the deposition reactor with argon to remove the previous reagents, the fibers coated with the interfacial phase were heat treated in argon for 1 hour at a temperature of 1400 ℃.

The preform is still held in its tool and is then consolidated by a ceramic layer, here a ceramic layer formed from methyltrichlorosilane (CH) at a temperature of about 1000-1040 ℃ and a pressure of 7.5 to 15kPa according to well known methods ₃ SiCl ₃ ) And hydrogen (H) ₂ ) Silicon carbide deposited by CVI. The consolidated preform is then removed from its gripping tool and its shape and size are maintained. Densification of the preform continues by CVI to form the ceramic matrix, where it is still formed by SiC infiltration. Note that other densification techniques as described above may be used. Densification continues here to form the silicon carbide matrix and complete the fabrication of the composite. It is also noted that the outer surface of the composite material may be protected by a coating that acts as a thermal barrier and/or Environmental Barrier (EBC). The purpose of this type of coating is to reduce the temperature in the composite and to protect the composite from corrosion in an oxidizing or humid environment. Such coatings are described, for example, in patents US7,544,394, WO9631687 (A1), US9,133,541 and US 2018363476.

After interfacial phase fabrication, heat treatment, preform consolidation and final densification steps, the composite material thus formed is processed into tensile test specimens without the need for an external EBC coating. The processing is performed to obtain a main direction of the sample following the reinforcement direction of the 2D composite. Tensile testing was then performed at room temperature and in air. The tensile specimen breaks at a stress of 300MPa and a relative elongation of 0.4%.

In comparative example 1', the tensile test specimen was processed from a SiC/BN/SiC composite material produced under the same conditions as in example 1, but using boron trichloride (containing no COCl) having a purity of 99.95% ₂ ) And pure gases of ammonia and hydrogenThe bulk mixture deposited a conventional 0.2 mu mBN interphase throughout its thickness. The results of stretching at room temperature and in air are the same as the previous results.

In example 2, the manufacturing process of the composite material according to the invention uses a fiber preform reinforced in two directions (2D). It is composed of Nicalon-NLM202 ^TM The fibers are made and subjected to a specific treatment to remove the natural oxides on their surface according to well known methods. The preform is placed in a clamping tool and the entire assembly is introduced into the deposition reactor (33) of fig. 2 to deposit the interfacial phase by CVI. In the first manufacturing step, a gas mixture consisting of ammonia and hydrogen with a purity of 99.95% and boron trichloride with the same purity was carried out at a temperature of 700 ℃ and a pressure of 1.3kPa for a period of 5 minutes. In the second manufacturing step, a gas mixture consisting of ammonia and hydrogen with a purity equal to 99.95%, boron trichloride with a purity equal to 99.95% and carbonyl dichloride with a concentration equal to 3% with respect to the boron trichloride was used for 150 minutes under the same temperature and pressure conditions. After the reaction gas was exhausted, the reactor was filled with argon and the temperature of the fiber preform was brought to 1100 ℃ in 2 hours. The preform, still held in its tool, is then consolidated by a ceramic layer, here silicon carbide infiltrated by CVI from a mixture of methyltrichlorosilane and hydrogen, according to the method already described in example 1. The consolidated preform is then removed from its gripping tool and its shape and size are retained. The preform continues to be densified by CVI to form a ceramic matrix. In that case, however, the matrix is no longer made solely of SiC, but rather of the self-repairing matrix described in the initial patent US5246736 and its variants US5965266 and WO 2018220296. Here, an alternating ternary system of SiC and SiBC is permeated from a mixture of hydrogen, methyltrichlorosilane and boron trichloride, and 3% COCl relative to boron trichloride is added ₂ (again corresponding to the use of boron trichloride purified only from its volatile impurities after synthesis). SiC penetrated under the same conditions as in example 1. The SiBC ternary composition is produced by chemical vapor infiltration at a temperature of 850 to 1150 ℃ and a pressure of 0.5 to 30 kPa.

After the steps of interfacial phase fabrication, heat treatment, consolidation of the preform and subsequent final densification of the self-healing matrix, two tensile specimens were processed in the composite material thus formed. The processing is performed in order to obtain a main direction of the sample, which follows the reinforcing direction of the 2D composite. After processing, each coupon was coated with a silicon carbide layer to close the pores created during processing. The properties of the selected fibers, which have a thermal stability of almost no more than 1100 ℃ and a low modulus (about 220 Gpa), and the use of self-healing matrices, make the composite particularly suitable for applications under moderate stresses and temperatures (600 to 1100 ℃). The test pieces were subjected to 120MPa of tensile/tensile fatigue test in air at 800 and 1050 ℃ respectively. For both temperatures, the lifetime was about 200 hours, which surprisingly, as seen in the comparative examples below, was higher than the values obtained using a conventional boron nitride interface phase according to the previous method.

In comparative example 2', the same test was carried out on a sample processed from a SiC/BN/SiC-SiBC composite material manufactured under the same conditions as in example 2, but deposited over its entire thickness with a pure gas mixture consisting of boron trichloride having a purity equal to 99.95% and ammonia, hydrogen, free of COCl, with a conventional BN interface phase ₂ . The results obtained in the tensile/stretching fatigue tests at 800 and 1050 ℃ respectively under 120MPa air were lower than the previous results, the service life being about 180 hours.

In example 3, the fiber used was Hi-Nicalon manufactured by Nippon Carbon ^TM A fiber, said fiber having a modulus of 270 GPa. Yarns made from this fiber are woven into thin 2D fabrics. Here, forced CVD/CVI infiltration is used on the gas mixture, which flows in a direction substantially perpendicular to the fabric surface, i.e. in an upward direction, allowing natural convection to be combined with forced convection and reduced pressure diffusion. A fabric is used here instead of the preform (36) of fig. 2. Which is arranged perpendicular to the direction of the gas flow into the reactor (33) of fig. 2 and which is almost closed by the fact that the passage between the reactor (33) and the susceptor (35) is almost completely closed The whole part of the susceptor (35) receiving the majority of the gas flow entering the reactor (33). This technique allows a slight pressure difference to be created between the surface exposed to the inflow of gas and the surface on its evacuation side towards the reactor outlet. Because of the small thickness of the fabric, gas flow by forced convection, natural upward convection, and diffusion under reduced pressure allow coating of all fibers under conditions where the reagent concentration at its surface is relatively close, but this depends on the relationship between the temperature of the process and mass transfer conditions, which has long been demonstrated in the case of deposition where the gas jet impinges on a planar surface (L.Vandenbulcke, J.Electrochem.Soc.124 (1977) 1932-1937). The temperature used here was 1300℃and the air pressure was 2kPa. In the first step, an interface layer of 0.04 μm was permeated with a gas mixture composed of ammonia and hydrogen with a purity of 99.95% and boron trichloride with a purity of 99.95%. In a second step, a gas mixture consisting of ammonia and hydrogen with a purity of 99.95%, boron trichloride with a purity of 99.95% and carbonyl dichloride with a ratio of 2% relative to boron trichloride was used under the same temperature and pressure conditions to reach a final interface phase thickness of 0.2 μm. The mixture of boron trichloride and carbonyl dichloride used again here corresponds to the synthesis of only the volatile substances thereof, such as Cl ₂ And COCl which is purified from HCl but has not been purified from its main impurity ₂ Boron trichloride purified in the process.

No heat treatment is performed here after the high temperature deposition. The high deposition temperature ensures good stability of the interfacial phase upon deposition. Twelve fabrics made from yarns containing fibers coated with their interfacial phase were tightly stacked in a perforated holding tool to allow gas to pass through. The fibrous structure thus formed is subsequently consolidated by a ceramic layer, where the ceramic layer is formed from methyltrichlorosilane (CH) according to well known methods at a temperature of about 1000-1040 ℃ and a pressure of 7.5 to 15kPa ₃ SiCl ₃ ) And hydrogen (H) ₂ ) Silicon carbide deposited by CVI. The consolidated preform is then removed from its gripping tool, where densification of the bonded fibrous structure continues by CVI to form a ceramic matrix that is still made of SiC.

A tensile specimen is processed in the composite material thus produced. The processing is performed in such a way that the main direction of the sample follows the reinforcing direction of the 2D composite. Tensile testing was then performed at room temperature and in air. The failure of the tensile specimen occurs at a stress of 290MPa and a relative elongation of 0.35%.

In comparative example 3', the tensile test specimen was processed from a SiC/BN/SiC composite material produced under the same conditions as in example 3, but using pure gas mixture of boron trichloride and ammonia, hydrogen gas having a purity of 99.95% (no COCl) ₂ ) The conventional 0.2 μm BN interfacial phase was deposited throughout its thickness. The results obtained by stretching at room temperature and in air are the same as the previous results.

These examples show that most of the interfacial phase between the fiber and the matrix can be made with boron trichloride, which is purified after synthesis to eliminate only high volatile materials. The boron trichloride contains, in particular, COCl in a concentration of more than 1% to about 5% ₂ Substances, avoiding the extra costs due to their difficulty in purification. The most important and unexpected results relate to the properties of the composite materials produced with the interfacial phases of the type described. The results were unchanged compared to composites made using previous methods of purifying boron trichloride to produce a conventional boron nitride interface phase. Surprisingly, the present invention even achieves better results than composites made with conventional boron nitride interface phases, as can be seen, for example, by comparison of examples 2 and 2'.

These examples are clearly not exhaustive, and many variants can be used, depending on the nature of the fibres, their arrangement in the yarn, fabric or fibre preform, the heat treatment conditions depending on the fibres and the manufacturing conditions of the fibres taking into account the structure of the yarn arrangement, the nature of the matrix used and the various infiltration processes present.

In addition, sublayers that are components of the interphase may be infiltrated. Thus, when boron trichloride is purified only from highly volatile chemicals, it also comprises silicon tetrachloride, especially when its synthesis is carried out in a silica tube. Can be manufactured in interfacial phaseAt the end of the first or second step, a silicon precursor is added to mixture H ₂ 、NH ₃ 、BCl ₃ (+COCl ₂ ) In BCl (binary coded decimal) ₃ The purity of (C) is equal to or higher than 99% or more than 1% of COCl ₂ Mixing to form a sub-layer with variable silicon proportion based on the Si-B-N ternary system. For example, according to L.Vandenbulcke et al (fifth International conference on high temperature ceramic matrix composites (Proceedings of the 5th International Conference on High Temperature Ceramic Matrix Composites) (2005) ISBN: 978-1-574-98263-3), an oxidation resistant layer is formed when the percentage of silicon is about 20 atomic percent. Thus, the ternary system may be used as a primer for the fiber-side or matrix-side interfacial phase. The silicon precursor added to the gas mixture during at least part or all of one of the two deposition or chemical infiltration steps is selected from the group consisting of silane, silicon chloride and methyltrichlorosilane.

To facilitate handling of the fabric, especially yarns, the interfacial phase may also be coated with a protective layer after it has been deposited at high temperature. The protective layer must be removable after the fibrous structure is manufactured and before the matrix is densified. Polymers dissolved in solvents and applied by dipping or spraying are generally used. The removal is essentially accomplished by heat treatment without leaving any residue on the surface of the fiber.

Finally, composite materials made according to any of the variants of the above method are an integral part of the present invention.

The embodiments presented in the foregoing description are obviously not limiting. Variations or modifications may be made therein by any person skilled in the art without departing from the scope of the present invention. The scope of the invention is, however, generally determined by the claims.

Claims (26)

1. A method of manufacturing a composite material (1) comprising a matrix of fibers (10) reinforced and composed mainly of ceramic, the matrix (11) comprising fibers coated with a thin layer called interface phase (12), characterized in that it comprises:

-in two consecutive steps without interruption, the manufacture of the interface phase being for forming a thin layer on the fibers by chemical deposition or chemical infiltration from a gaseous phase consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9% and boron trichloride with a purity equal to or greater than 99%, then in a second manufacturing step, the gaseous phase consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9%, boron trichloride with a purity less than 99% and carbonyl dichloride with an atomic percentage concentration relative to boron trichloride greater than 1%, the duration of the first step being less than or equal to 20% of the total duration of the manufacture of the interface phase, the final thickness of the interface phase being between 0.1 and 1 μm;

-after coating the interfacial phase on the fibers, subjecting said interfacial phase coated fibers to a heat treatment, without exposure to an oxidizing atmosphere, at a temperature equal to or higher than 1100 ℃ for a duration of less than 4 hours;

-subsequently effecting the manufacture of a composite material by including the interfacial phase coated fibers in said matrix.

2. The method of claim 1, wherein in the first step, the interfacial phase is produced with boron trichloride having a purity of 99.5% or greater.

3. The method according to claim 1, wherein in the second step of manufacturing the interfacial phase, boron trichloride is purified only from highly volatile components having a boiling point below 0 ℃ after synthesis.

4. The method of claim 1, wherein a silicon precursor is added to the gaseous mixture during at least part or all of one of the two chemical deposition or infiltration steps, the precursor being taken from the group consisting of: silane, and one of silicon chloride and methyltrichlorosilane.

5. The method of any one of claims 1 to 4, wherein the fibers are carbon, alumina, mullite or silicon carbide fibers.

6. The method as claimed in claim 5, wherein the silicon carbide fiber contains carbon and silicon as main elements, and the concentration of oxygen is 0.05 to 14% in terms of atomic percentage among other impurities.

7. The method of any one of claims 1 to 4, wherein the fibers constitute a yarn comprising several hundred fibers or a fabric made by weaving, braiding or knitting the yarn.

8. The method according to claim 7, wherein the interfacial phase is produced by forced chemical deposition/infiltration from the gas phase, i.e. forced CVD/CVI, in a deposition chamber where the direction of flow of the incident gas phase and the main direction of the yarn or the plane of the fabric are at an angle of more than 20 degrees, the interfacial phase being produced at a temperature equal to or greater than 1100 ℃ and a pressure of 0.2 to 10 kPa.

9. The method as recited in claim 8, wherein the yarn or yarns comprising fibers, or the fabric, remain stationary in the deposition chamber.

10. The method of claim 8, wherein the yarn or yarns, or fabric, passes through the deposition chamber at a speed of 2 to 500 cm per minute.

11. The method according to any one of claims 8 to 10, wherein the interfacial phase is produced by forced chemical deposition/infiltration from the gas phase, i.e. forced CVD/CVI, in a deposition reactor where the position of the yarn or fabric is horizontal and the gas flow from the inlet to the outlet of the chemical deposition/infiltration reactor is substantially upward, mass transfer being carried out to all fibres by forced convection combined with natural upward convection and reduced pressure diffusion.

12. A method according to any one of claims 1 to 4, wherein the fibres constitute a three-dimensional preform made from a three-dimensional weave of yarns or a weave of yarns into a woven layer or a stack of woven layers, the woven layer being held in the stack by holding means consisting of a porous solid material that allows gas to pass through the fibres constituting the yarns.

13. The method of claim 12, wherein the interfacial phase is produced from the gas phase by continuous chemical permeation or pulsed chemical permeation at a temperature of 650 to 900 ℃ and a pressure of 0.1 to 5 kPa.

14. A method as claimed in claim 12, wherein after heat treatment of the fibres coated with the interfacial phase, the preform is consolidated with the first layer of matrix made by CVI using a clamping tool, and densification of the matrix is continued after the preform has been removed from its clamping tool.

15. The method according to any one of claims 1 to 4, wherein the heat treatment is performed at a temperature of 1100 ℃ to 1600 ℃ for a duration of less than or equal to 2 hours, depending on the properties of the fiber.

16. The method of claim 15, wherein the temperature and time of the heat treatment are such that the nominal intrinsic modulus of elasticity of the fiber as indicated by the fiber manufacturer does not change by more than 5% under an inert atmosphere.

17. The method of any one of claims 1 to 4, wherein the matrix consists of at least one material from the group of oxides, carbides, nitrides or silicides, or a combination of materials from at least one of them.

18. The method of claim 17, wherein the substrate is made of silicon carbide.

19. The method of any one of claims 1 to 4, wherein the embedding of the interfacial phase coated fibers into the matrix is performed at least in part by Chemical Vapor Infiltration (CVI).

20. The method of claim 19, wherein the substrate is comprised of layers of different properties, the layers comprising silicon carbide and one carbide from a boron carbon binary or silicon boron carbon ternary system.

21. The method of claim 20 wherein said substrate is comprised of layers of different properties, said layers comprising silicon carbide and a carbide from the binary or ternary boron-carbon boron system, the boron element being provided in all of said layers by a gas phase comprising boron trichloride having a purity of less than 99%.

22. The method of any one of claims 1 to 4, wherein the interfacial phase coated fiber embedding matrix is at least partially performed by impregnation with at least one polymer precursor of a ceramic followed by pyrolysis.

23. The method of any one of claims 1 to 4, wherein the embedding of the interfacial phase coated fibers into the matrix is achieved at least in part by introducing carbon and ceramic powder into the spaces between the fibers and infiltrating the silicon-based metal in a molten state.

24. The method of any one of claims 1 to 4, wherein the composite material comprises the following enhancements: fiber reinforcement, i.e. 1D composite, constituting the elongated yarns in one main reinforcement direction; yarn reinforcement, i.e. 2D composite, constituting a fabric with two main directions of reinforcement; or additionally comprises a partially reinforced yarn reinforcement in a third direction, i.e. a 2.5D composite; or a yarn reinforcement constituting reinforcement in the nth direction, where N is 3 or more.

25. A method of manufacturing a composite material comprising a matrix of ceramic and fibre reinforcement, the matrix comprising fibres coated with a thin layer called interface phase, the method comprising:

-in two consecutive steps without interruption, the manufacture of the interfacial phase being for forming a thin layer on the fibers by chemical deposition or chemical infiltration from a gaseous phase consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9% and boron trichloride with a purity equal to or greater than 99%, then in a second manufacturing step consisting of a gaseous mixture consisting of at least ammonia and hydrogen with a purity equal to or greater than 99.9%, boron trichloride with a purity less than 99% and carbonyl dichloride with an atomic percentage concentration of greater than 1% relative to boron trichloride, the first step being for a duration of less than or equal to 20% of the total duration of the manufacture of the interfacial phase, the final thickness of the interfacial phase being between 0.1 and 1 μm, the manufacture being carried out on one or more yarns or 2D fabrics according to the forced CVD/CVI method at a temperature greater than 1100 ℃;

-subsequently effecting the manufacture of a composite material by including the interfacial phase coated fibers in said matrix.

26. A composite material manufactured by the method of any one of claims 1-25.