CN115677355B - Fiber surface Si 3 N 4 Nano-network composite interface phase layer and preparation method thereof - Google Patents
Fiber surface Si 3 N 4 Nano-network composite interface phase layer and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a fiber surface Si 3 N 4 A nano-network composite interface phase layer and a preparation method thereof. The Si grows on the surface of the fiber in situ 3 N 4 The method for the nano-network structure composite interface phase layer comprises the following steps: depositing Si on the surface 3 N 4 Performing heat treatment on the fiber or the fiber braid of the interface phase layer to obtain Si 3 N 4 A nano-network structure composite interface phase layer; the heat treatment includes: (1) Firstly, under 1450-1750 deg.C, vacuum or pressure is 10 Pa-20 Kpa N 2 Or/and Ar for 0.1 to 2 hours; (2) Then N with the pressure of 70Kpa to 1000Kpa is arranged at 1450 to 1750 DEG C 2 Or/and NH 3 And the mixture is kept in the atmosphere for 0.1 to 2 hours.
Description
Technical Field
The invention belongs to the field of composite material preparation, and relates to a method for growing Si on the surface of a fiber 3 N 4 A nano-network composite interface phase layer and a preparation method thereof.
Background
The SiC/SiC ceramic matrix composite has the advantages of high temperature resistance, high specific strength, non-brittle fracture failure mode under the action of stress and the like, is considered as an important candidate material for the hot end part of the aeroengine, and is widely paid attention to. In the SiC/SiC composite material, the composite material is strengthened and toughened by introducing micron-sized fibers into a ceramic matrix, so that the tolerance of the ceramic matrix to damage is improved. Si (Si) 3 N 4 Has lower modulus, superior thermal shock resistance, and more excellent oxidation resistance than SiC, and the excellent characteristics enable Si to be 3 N 4 Becomes a critical interfacial phase of the composite material. During the service process of the composite material, the composite material is impacted by thermal stress, a large number of microcracks are generated in the matrix due to Si 3 N 4 Intrinsic interfacial brittleness, conduction from the matrix to Si at microcracks 3 N 4 Si at interface 3 N 4 Failure occurs and the crack is conducted to the inner layer interface and the fibers. Under the action of cyclic stress, cracks in the matrix can further proliferate and expand to become oxygen diffusion channels, and finally the composite material is damaged in a disastrous way. Improving the Si of the ceramic matrix composite 3 N 4 The ability of interfaces to resist damage becomes a very critical issue.
At present, related researches are carried out to improve the anti-damage capability of the composite material by preparing nano wires on the surface of an interface layer as reinforcements. CN107285793a proposes that the damage resistance of the composite material micro-area matrix is improved by in-situ growth of micro-nano scale multi-stage SiC nanowires on the interface surface. In-situ growth of Si inside carbon felt by precursor impregnation-cracking method in CN104926348A 3 N 4 A nanowire. The method comprises the steps of growing micro-nano-scale SiC and Si in situ 3 N 4 The nano wire can realize deflection of cracks of the composite material matrix and improve the anti-damage capability of the material. The nanowire reinforcement also has a certain problem that nanowires grow divergently on the interface surface of the composite material, and the density difference between the nanowires at the near end and the far end of the fiber surface is large due to the ultrahigh length-diameter ratio of the nanowires, so that the problem of too high porosity of the material can be caused in the subsequent densification process, and the existence of the pores is unfavorable for the material.
Therefore, the in-situ growth of the nanowire reinforcement on the interface surface is not complete enough for improving the performance of the composite material, and a novel nano-network structure interface phase is required to be uniformly coated on the fiber surface so as to improve the mechanical property and the anti-damage capability of the ceramic matrix composite material.
Disclosure of Invention
In order to solve the above problems, the present invention provides a new solution: in situ growth of Si on fiber surface 3 N 4 A nano-network structure composite interface. Firstly, a layer of Si is grown on the surface of the fiber in situ by a chemical vapor deposition method 3 N 4 Interfacial phase, and then to the Si obtained 3 N 4 Performing surface heat treatment on the interface to obtain Si with nano-network structure on the surface 3 N 4 And (3) a composite interface.
In one aspect, the present invention provides an in situ growth of Si on a fiber surface 3 N 4 Method for preparing composite interface phase layer with nano-network structure by depositing Si on surface 3 N 4 Performing heat treatment on the fiber or the fiber braid of the interface phase layer to obtain Si 3 N 4 A nano-network structure composite interface phase layer; the heat treatment includes: (1) Firstly, under 1450-1750 deg.C, vacuum or pressure is 10 Pa-20 Kpa N 2 Or/and Ar for 0.1 to 2 hours; (2) Then N with the pressure of 70Kpa to 1000Kpa is arranged at 1450 to 1750 DEG C 2 Or/and NH 3 And the mixture is kept in the atmosphere for 0.1 to 2 hours.
In the invention, si grows in situ on the surface of the fiber 3 N 4 Composite interface of nano network structure utilizing Si 3 N 4 Branching the generated cracks by the network structure with the nano-scale surface, and avoiding the conduction of the microcracks to Si 3 N 4 Brittle fracture is directly generated at the interface, so that the matrix and the interface are strengthened and toughened. Thus, si is constructed 3 N 4 The nano-network structure composite interface has important significance.
Preferably, the fibers are oxide fibers (e.g., al 2 O 3 Fibers, zrO 2 Fibers, etc.) or non-oxide fibers (preferably C fibersOr SiC fibers); the fiber braid is an oxide fiber braid or a non-oxide fiber braid (preferably a C-fiber braid or a SiC-fiber braid).
Preferably, the fiber or the fiber preform further comprises at least one layer selected from a PyC layer, a BN layer, a SiC layer, a SiBN layer, and a SiBCN layer.
Preferably, the diameter of the fibers is 5 μm to 0.5mm.
Preferably, the Si 3 N 4 The thickness of the interfacial layer is 0.1 μm to 3 μm.
Preferably, the chemical vapor deposition process is adopted to deposit Si on the surface of the fiber or the fiber braiding body at the temperature of 700-1100 ℃ and the pressure of 1 KPa-10 KPa 3 N 4 Interfacial phase layers.
Also, preferably, si is prepared by chemical vapor deposition 3 N 4 The interfacial phase layer further comprises: siH (SiH) 4 、SiCl 4 、SiHCl 3 、SiH 2 Cl 2 As a silicon source; NH (NH) 3 As an organic precursor; n (N) 2 、Ar、H 2 At least one of them is used as a diluent gas.
Also, preferably, the silicon source and NH 3 The mole fraction ratio of (2) is (0.05): 1, a step of; preferably (0.2 to 0.5): 1, a step of;
the mole fraction ratio of the silicon source to the diluent gas is (0.01-5): 1, a step of; preferably (0.05 to 0.1): 1, a step of;
the total time of the chemical vapor deposition is 1 to 20 hours, preferably 8 to 15 hours.
Preferably, in the step (2) of the heat treatment, the air pressure is 100KPa to 300KPa.
Preferably, the heat treatment is performed continuously in the same high temperature furnace.
In another aspect, the present invention provides Si prepared according to the above method 3 N 4 And a nano-network structure composite interfacial phase layer.
The beneficial effects are that:
in the invention, the in-situ growth of Si on the surface of the fiber is creatively explored for the first time 3 N 4 Composite interface of nano network structurePhase preparation method, obtaining Si with network structure coating 3 N 4 And (3) compounding an interfacial phase. The preparation process of the invention has the advantages of simplicity, controllability, low cost and short period.
Drawings
FIG. 1 is Si prepared in example 1 3 N 4 Interface scanning electron microscope pictures;
FIG. 2 is Si prepared in example 1 3 N 4 Scanning electron microscope pictures of the composite interface of the nano network structure;
FIG. 3 is Si prepared in example 1 3 N 4 High-power scanning electron microscope pictures of the composite interface of the nano network structure;
FIG. 4 is Si prepared in example 2 3 N 4 Scanning electron microscope pictures of the composite interface of the nano network structure.
Detailed Description
The invention will be further described in connection with the following embodiments, it being understood that the drawings and the following embodiments are only for illustrating the invention, and not for limiting the invention.
In the invention, si grows on the surface of the fiber or the fiber woven body in situ through chemical vapor deposition in-situ growth and high-temperature heat treatment 3 N 4 A nano-network structure composite interface. The Si is 3 N 4 The composite interface of the nano-network structure is Si with the surface uniformly coated with the nano-scale network structure 3 N 4 And (3) a composite interface. The fiber braid means a fiber structure in which fibers are formed by braiding.
The preparation process of the invention has the advantages of simplicity, controllability, low cost and short period, and effectively obtains the Si with uniform coating and distinct scale 3 N 4 A nano-network structure composite interface. The following exemplary description of in situ growth of nano-network structure Si in fibers 3 N 4 A preparation method of a composite interfacial phase.
The fiber woven body is ultrasonically cleaned by absolute ethyl alcohol and then is placed in an oven for drying. As an example), silicon carbide fibers or fiber braiding bodies prepared by the silicon carbide fibers are soaked in absolute ethyl alcohol for ultrasonic cleaning, and particle impurities possibly existing on the surfaces of the silicon carbide fibers or fiber braiding bodies are removed and then placed into an oven for drying. Wherein the ultrasonic cleaning time can be 0.1 to 5 hours.
Adopting chemical vapor deposition process to deposit Si on the surface of the fiber in the fiber woven body at the temperature of 700-1100 ℃ and the pressure of 1 KPa-10 KPa 3 N 4 Interfacial phase layers.
Will deposit long Si 3 N 4 Continuously placing the fiber or fiber braid of the interface phase layer into a high temperature furnace, raising the temperature to 1450-1750 ℃, maintaining the pressure of 10 Pa-20 Kpa for 0.1-2 h, and aiming at Si 3 N 4 The decomposition reaction is carried out under high temperature and high vacuum to form Si and N 2 ，N 2 The volatilization occurs, through which the liquid Si can be combined with the underlying Si at high temperature 3 N 4 The N element in the silicon is reacted to generate Si 3 N 4 Lower layer Si 3 N 4 The Si is changed into liquid phase Si, which can generate certain agglomeration due to surface tension, and a porous structure is generated on the interface surface. Keeping the temperature at 1450-1750 ℃ continuously after keeping the low pressure for 0.1-2 h, and introducing N 2 、NH 3 At least one of them is kept at a pressure of 70Kpa to 1000Kpa for a period of 0.1 to 2 hours, and is aimed at maintaining the pressure at high temperature and high pressure in an excess of N 2 Or NH 3 Liquid phase Si energy and N under atmosphere 2 、NH 3 The N atoms in the silicon react to generate Si 3 N 4 Finally form Si 3 N 4 A nano-network structured interface. The heat treatment is continuously carried out in the same high temperature furnace.
In alternative embodiments, the fibers may be C fibers, siC fibers. The fiber braid has a composition of C fibers, siC fibers, or the like. Preferably, the surface of the fibers or the surface of the fibers in the fiber weave has been deposited with P y C. BN, siC, siBN, siBCN, etc.
The present invention will be further illustrated by the following examples. It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, since numerous insubstantial modifications and variations will now occur to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below.
Example 1
The woven body of silicon carbide fibers (SiC fibers having a diameter of 13 μm) was washed in an ethanol solution, and then taken out and dried under vacuum. Placing the dried silicon carbide fiber braid into chemical vapor deposition equipment, heating to 950 ℃ under argon atmosphere, stopping argon, and introducing SiCl 4 、NH 3 And H 2 ，SiCl 4 /NH 3 The mole fraction ratio is 0.2, the furnace pressure is 2KPa, and the reaction time is 10h. After the reaction is finished, the gas is closed, and the mixture is cooled to room temperature under the argon atmosphere to obtain Si 3 N 4 Interfacial phase layer (thickness 1 μm). The obtained silicon-deposited material is 3 N 4 And continuously placing the fiber braid at the interface into a high-temperature furnace for further treatment, heating to 1550 ℃ under the argon atmosphere, controlling the pressure at 1Kpa, and preserving the heat for 1h. Continuously raising the temperature to 1620 ℃, and introducing NH 3 The pressure was adjusted to 200Kpa and the reaction time was 0.5h. After the reaction is finished, the gas is closed, and the mixture is cooled to room temperature under the argon atmosphere to obtain Si 3 N 4 A nano-network composite interface.
Table 1 shows Si prepared in example 1 3 N 4 EDS results for interfacial phase layer:
| elemental composition | wt％ | wt％Sigma | Atomic percent |
| C | 3.43 | 0.46 | 5.39 |
| N | 39.76 | 0.60 | 53.58 |
| O | 5.63 | 0.38 | 6.64 |
| Si | 51.18 | 0.58 | 34.39 |
| Total amount of | 100.00 | - | 100.00 |
。
As can be seen from FIG. 1 and Table 1, the in-situ growth of the fiber surface yielded Si 3 N 4 And (5) an interface. As can be seen from FIGS. 2 and 3, the surface of the fiber is uniformly coated with Si 3 N 4 A nano-network structure composite interface.
Example 2
Si obtained in example 1 was used 3 N 4 And (3) performing high-temperature treatment in the steps 3 and 4 on the interfacial phase layer. The obtained silicon-deposited material is 3 N 4 The fiber braid at the interface is put into a high temperature furnace, heated to 1450 ℃ under the nitrogen atmosphere, the pressure is controlled at 400Pa, and the temperature is kept for 1.5h. Continuously raising the temperature to 1500 ℃, and introducing N 2 The pressure was adjusted to 120Kpa and the reaction time was 1h. After the reaction is finished, cooling to room temperature under nitrogen atmosphere to obtain Si 3 N 4 The nanonetwork composite interface is shown in fig. 4.
Example 3
The Si deposited obtained in example 1 3 N 4 And continuously placing the fiber braid at the interface into a high-temperature furnace for further treatment, heating to 1550 ℃ under the argon atmosphere, controlling the pressure at 1Kpa, and preserving the heat for 1h. The reaction was continued at 1550℃under a pressure of 200Kpa for a reaction time of 0.5h.
Comparative example 1
The Si deposited obtained in example 1 3 N 4 And continuously placing the fiber braid at the interface into a high-temperature furnace for further treatment, heating to 1550 ℃ under the argon atmosphere, controlling the pressure at 1Kpa, and preserving the heat for 1h. The temperature was continuously raised to 1620℃and the pressure was 1Kpa and the reaction time was 0.5h. At this time, only low-pressure heat treatment is adopted, so that Si 3 N 4 The decomposition forms Si simple substance, which is extremely disadvantageous for improving the damage resistance of the composite material micro-domain matrix even if it has a porous structure.
Comparative example 2
The Si deposited obtained in example 1 3 N 4 And continuously placing the fiber braid at the interface into a high-temperature furnace for further treatment, heating to 1550 ℃ under the argon atmosphere, controlling the pressure at 200Kpa, and preserving the heat for 1h. The temperature was continuously raised to 1620℃and the pressure 200Kpa and the reaction time 0.5h. At this time, only high-pressure heat treatment is adopted, si 3 N 4 The interfacial layer does not change, and the surface is smooth and still dense.
As can be seen from comparison of FIG. 3 and FIG. 4, the nanocomposite interface in example 1 has a more complete and ordered structure, and the liquid Si has higher reactivity and NH at higher temperature and pressure 3 Ratio N 2 Is easier to react with liquid phase silicon, and the generated nano-network structure is more uniform.
Claims (9)
1. In-situ growth of Si on fiber surface 3 N 4 Nano network structure complexA method for forming an interfacial layer, characterized in that Si is deposited on the surface 3 N 4 Performing heat treatment on the fiber or the fiber braid of the interface phase layer to obtain Si 3 N 4 A nano-network structure composite interface phase layer; the fibers are oxide fibers or non-oxide fibers; the fiber braid is an oxide fiber braid or a non-oxide fiber braid, and the Si 3 N 4 The thickness of the interfacial layer is 0.1-3 mu m; the heat treatment includes: (1) Firstly, at 1450-1750 deg.C, vacuum or pressure is 10 Pa-20 KPa N 2 Or/and Ar for 0.1 to 2 hours; (2) Then at 1450-1750 ℃ and the pressure of 70 KPa-1000 KPa 2 Or/and NH 3 And the mixture is kept in the atmosphere for 0.1 to 2 hours.
2. The method of claim 1, wherein the fiber or fiber braid further comprises at least one of a PyC layer, a BN layer, a SiC layer, a SiBN layer, and a SiBCN layer.
3. The method according to claim 1, wherein the fibers have a diameter of 5 μm to 0.5mm.
4. The method according to claim 1, wherein the Si is deposited on the surface of the fiber or fiber braid by chemical vapor deposition at a temperature of 700 to 1100 ℃ and a pressure of 1 to 10KPa 3 N 4 Interfacial phase layers.
5. The method of claim 4, wherein Si is prepared by chemical vapor deposition 3 N 4 The interfacial phase layer further comprises: siH (SiH) 4 、SiCl 4 、SiHCl 3 、SiH 2 Cl 2 At least one of which is used as a silicon source and NH 3 N as a nitrogen source 2 、Ar、H 2 At least one of them is used as a diluent gas.
6. The method of claim 5, wherein the silicon source is combined with NH 3 Molar fraction of (2)The number ratio is (0.05-2): 1, a step of;
the mole fraction ratio of the silicon source to the diluent gas is (0.01-5): 1, a step of;
the total time of the chemical vapor deposition is 1-20 hours.
7. The method of claim 6, wherein the silicon source is combined with NH 3 The mole fraction ratio of (2) to (0.5): 1, a step of;
the mole fraction ratio of the silicon source to the diluent gas is (0.05-0.1): 1, a step of;
the total time of the chemical vapor deposition is 8-15 hours.
8. The method according to any one of claims 1 to 7, wherein the gas pressure in the step (2) of the heat treatment is 100KPa to 300KPa.
9. Si prepared according to the method of any one of claims 1-8 3 N 4 And a nano-network structure composite interfacial phase layer.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102619081A (en) * | 2012-03-31 | 2012-08-01 | 中材高新材料股份有限公司 | Preparation technology for preparing interface layer of boron nitride fabric through CVD (Chemical Vapor Deposition) |
| CN103086731A (en) * | 2011-10-28 | 2013-05-08 | 中国科学院上海硅酸盐研究所 | Micro-region in-situ reaction preparation method for high strength fiber-reinforced ceramic matrix composite material |
| CN103664214A (en) * | 2012-09-13 | 2014-03-26 | 南京航空航天大学 | Preparation method of wave-transparent composite material containing silicon nitride interface |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6630413B2 (en) * | 2000-04-28 | 2003-10-07 | Asm Japan K.K. | CVD syntheses of silicon nitride materials |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103086731A (en) * | 2011-10-28 | 2013-05-08 | 中国科学院上海硅酸盐研究所 | Micro-region in-situ reaction preparation method for high strength fiber-reinforced ceramic matrix composite material |
| CN102619081A (en) * | 2012-03-31 | 2012-08-01 | 中材高新材料股份有限公司 | Preparation technology for preparing interface layer of boron nitride fabric through CVD (Chemical Vapor Deposition) |
| CN103664214A (en) * | 2012-09-13 | 2014-03-26 | 南京航空航天大学 | Preparation method of wave-transparent composite material containing silicon nitride interface |
Non-Patent Citations (1)
| Title |
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| 刘永胜等.CVI制备C/Si3N4复合材料及其表征.《无机材料学报》.2005,第20卷(第5期),第1209页第1,4段，表1. * |
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