CN113248263B - Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method for compounding materials - Google Patents
Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method for compounding materials Download PDFInfo
- Publication number
- CN113248263B CN113248263B CN202110570198.7A CN202110570198A CN113248263B CN 113248263 B CN113248263 B CN 113248263B CN 202110570198 A CN202110570198 A CN 202110570198A CN 113248263 B CN113248263 B CN 113248263B
- Authority
- CN
- China
- Prior art keywords
- powder
- preform
- slurry
- composite material
- whisker
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
- C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
- C04B2235/52—Constituents or additives characterised by their shapes
- C04B2235/5208—Fibers
- C04B2235/5216—Inorganic
- C04B2235/524—Non-oxidic, e.g. borides, carbides, silicides or nitrides
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
- C04B2235/602—Making the green bodies or pre-forms by moulding
- C04B2235/6022—Injection moulding
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
- C04B2235/6562—Heating rate
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
- C04B2235/6567—Treatment time
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Ceramic Products (AREA)
Abstract
The invention relates to Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 The method of the composite material takes hydrochloric acid as a pH regulator, and introduces Si powder and Si under the acidic condition 3 N 4 The forming of the whisker preform is combined, so that the stability of micron-sized Si powder with higher specific surface area in water-based slurry is improved; simultaneously, the polyvinyl alcohol is taken as a dispersant, thereby realizing the Si 3 N 4 Stable dispersion of whiskers in acidic slurry to obtain Si 3 N 4w the/Si complex phase high volume fraction synergetic stable suspension slurry. The volume of the Si powder expands in the nitridation reaction process, so that the pores in the prefabricated body can be effectively occupied; porous Si 3 N 4w Putting the/Si prefabricated body into a nitriding furnace, and introducing N 2 Nitriding the Si powder in the preform to form Si 3 N 4 In-situ forming silicon nitride on the whisker to obtain Si 3 N 4w /Si 3 N 4 A composite material. The method developed by the invention is suitable for preparing large-size components with complex shapes, and the high-performance ceramic matrix composite material with isotropy and small residual stress can be obtained by combining gel casting with in-situ reaction.
Description
Technical Field
The invention belongs to the preparation of whisker reinforced composite materials, and relates to Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 A method of compounding a material. In particular to gel injection molding Si 3 N 4w Si preform, by nitridation of Si 3 N 4 In situ preparation of Si on whiskers 3 N 4 Matrix, thereby obtaining Si 3 N 4w /Si 3 N 4 The preparation method of the composite material is mainly applied to the technical field of wave-transparent ceramic manufacturing.
Background
The wave-transparent composite material can protect a radar antenna system from the influence of the external severe environment, provides an electromagnetic window for the transmission and the reception of electromagnetic waves of the antenna, and ensures the long-term high-efficiency operation of the antenna. The wave-transmitting material for the antenna housing generally has low dielectric constant, low loss and high electromagnetic wave transmittance, and simultaneously has certain mechanical properties such as high strength, high temperature resistance, stable structure and the like, and structural designability.
Silicon nitride (Si) 3 N 4 ) The ceramic is combined by covalent bonds, has excellent mechanical properties, higher thermal stability, low thermal expansion coefficient, good thermal shock resistance and moderate dielectric constant, and can be applied to the field of high-temperature wave-transparent ceramics. The silicon nitride ceramic prepared by the traditional sintering and forming process has high density and high strength, but the high density leads the dielectric constant of the ceramic to be higher, which is not beneficial to improving the wave-transmitting performance; meanwhile, the added sintering aid has certain adverse effects on the high-temperature performance and the wave-transmitting performance of the material; in addition, large-scale shrinkage exists in the sintering process, so that the preparation of a large-size component with a complex shape is difficult, and the prepared component has large residual stress, so that the long-term use of the component is not facilitated. Researchers put forward the design idea of porous silicon nitride ceramics, and the dielectric constant of the ceramics is obviously reduced by introducing pores, so that the wave-transparent performance of the ceramics is improved. However, the preparation process of the porous silicon nitride ceramic still mainly takes sintering as a main part at present, and the adverse effects of volume shrinkage of the sintering aid and the ceramic in the sintering process on the material performance and the forming control are still not effectively eliminated.
The silicon nitride crystal whisker is a single crystal material, has excellent mechanical property, can keep stable at high temperature, and is not easy to grow crystal grains or generate other defects. In the early period of the team, the silicon nitride whisker is used as a raw material, and a silicon nitride whisker preform with porous structure characteristics, certain bearing capacity and excellent wave-transmitting performance is formed by adopting a gel casting process. In the whisker preform formed by gel casting, the bonding between whiskers is weaker, and in order to improve the strength and rigidity of the material, a silicon nitride base is prepared in the silicon nitride whisker preform by adopting the processes of precursor impregnation cracking (PIP), chemical Vapor Infiltration (CVI) and the likeFinally obtaining the silicon nitride whisker reinforced silicon nitride ceramic matrix composite material (Si) with good mechanical property and wave-transmitting property 3 N 4w /Si 3 N 4 ). The gel casting is combined with the PIP/CVI combined process, and impurities such as sintering aids and the like are not introduced into the material; meanwhile, the gel casting process has the advantages of simple operation, low cost, near net size and the like; compared with PIP and CVI methods, the PIP and CVI methods have lower preparation temperature and smaller material size change in the process of preparing the substrate by the two methods. Therefore, the combined process of gelcasting combined with PIP/CVI solves the problems of the conventional sintering process to some extent. However, specific analysis shows that when a substrate is prepared in a silicon nitride whisker preform by a PIP process, the substrate produced usually has defects such as hole cracks and the like due to certain shrinkage in the process of converting a liquid polymer precursor into ceramic, and the inside of the material still has certain stress; when the matrix is prepared by adopting a CVI (chemical vapor infiltration) process, micron-sized pores in the whisker preform are not beneficial to full diffusion of a gaseous precursor, the micron-sized pores are easy to nucleate at pore diameters so as to seal pores, and the prepared matrix is in gradient distribution, namely, the surface is more, the interior is less, and the matrix is not beneficial to whisker bearing. Therefore, there is still a need to find a new silicon nitride substrate preparation process matched with the gel injection molding preparation of silicon nitride whisker preform to solve the above problems and further improve Si 3 N 4w /Si 3 N 4 The comprehensive performance of the composite material.
The invention provides a method for preparing a silicon nitride substrate by adopting Si powder nitridation, which fills the pores of a prefabricated body by utilizing the volume expansion in the process of Si powder nitridation reaction and avoids the problem of shrinkage stress generated by other processes. It is worth proposing that in the invention, the Si powder is not introduced in a dipping mode by preparing Si powder slurry after the silicon nitride whisker preform is formed, but the Si powder and the silicon nitride whisker are mixed to prepare slurry and are introduced together by a gel injection molding process when the whisker preform is formed. The invention adopts micron-sized Si powder to ensure that the matrix generated by the subsequent nitridation reaction is uniformly distributed. Stable dispersion of micron-sized Si powder in gel casting process slurry and Si in acidic slurry 3 N 4w The synergistic stable dispersion with Si powder will be the technical idea of the present inventionThe key to implementation is no.
The gel casting process is to form a three-dimensional network structure by reacting a monomer and a cross-linking agent at a certain temperature, and fix ceramic powder in the three-dimensional network structure to realize low-temperature ceramic molding. When the slurry is prepared, the dispersant, the pH regulator and the like are added to realize uniform mixing of the slurry. Due to the surface charge characteristics of the silicon nitride powder, the dispersibility of the silicon nitride powder in the slurry is closely related to the pH value of the slurry. Studies have shown that when the slurry pH is adjusted>7, the silicon nitride surface groups will adsorb [ OH-]The surface of the particles is negatively charged to form an electric double layer. Along with the increase of the pH value, the thickness of the double electric layers on the surfaces of the particles is increased, the interparticle repulsive force is increased, the dispersibility of the silicon nitride particles is improved, the viscosity of the slurry is reduced, and the system stability can be realized. However, aiming at the technical assumption provided by the invention, si is easy to hydrolyze in an alkaline environment to generate bubbles due to the difference of the properties of the original powder; meanwhile, although the activity of the large-particle-size Si powder is low and the large-particle-size Si powder can be kept stable in the alkaline slurry under the condition of low volume fraction, the size of a matrix formed after the large-particle-size Si powder is nitrided is large, the matrix is not easy to be uniformly distributed, and the reinforcing effect is limited; however, the specific surface area of the Si powder with the particle size of less than 10 microns is large, the reaction activity is higher, stable dispersion cannot be realized in alkaline slurry, and the performance control of the final material is not facilitated; although SiO is formed by surface modification, e.g. oxidation, of Si powder 2 And the method of layer and the like can realize the stability of the oxide layer in the alkaline slurry, but the oxide layer has a barrier effect on the subsequent nitridation reaction and is not beneficial to the regulation and control of material performance.
Aiming at the problems, the invention provides a method for adjusting the pH of slurry by using hydrochloric acid as a pH regulator<7, forming a positive ion layer on the surfaces of the silicon nitride and the Si, and realizing the stability of the Si powder; meanwhile, a certain amount of dispersant polyvinyl alcohol (PVA) is added, hydrophobic groups in molecules of the PVA can be adsorbed on the surfaces of the solid particles, and hydroxyl groups in the molecules have hydrophilic characteristics, so that a potential barrier layer can be formed on the surfaces of the solid particles, particle aggregation and gravity settling are hindered, and uniform dispersion of the mixed powder is realized. After the mixed slurry of the silicon nitride crystal whisker and the Si powder with proper viscosity is obtained by adjusting the pH value, the content of a dispersant, the volume fraction of a solid phase and the like of the slurry, the gelation is carried out at low temperature to realize the gelation of Si 3 N 4w Si green bodyAnd (5) molding. Then, si is converted into a silicon nitride matrix by high-temperature nitridation, thereby obtaining a silicon nitride whisker reinforced silicon nitride composite material (Si) 3 N 4w /Si 3 N 4 )。
Disclosure of Invention
Technical problem to be solved
In order to avoid the defects of the prior art, the invention provides Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 The composite material is prepared through compounding silicon nitride crystal whisker and Si powder to form homogeneous, isotropic and near-net-size three-dimensional netted Si structure 3 N 4w Si preform, then introducing nitrogen gas into the preform to cause the nitridation reaction of the Si powder, and forming a silicon nitride substrate on the silicon nitride whisker in situ, thereby obtaining Si 3 N 4w /Si 3 N 4 A composite material.
Technical scheme
Si 3 N 4w the/Si prefabricated body is characterized in that the components are Si powder and Si with the volume ratio of 1:2-10 3 N 4 A whisker, wherein: the grain size of the Si powder is 1-10 μm, and the length-diameter ratio of the crystal whisker is 5-20.
By using the Si 3 N 4w Preparation of Si from Si preform 3 N 4w /Si 3 N 4 A method of compounding a material, characterized by the steps of:
step 1, preparing slurry: 40 to 55wt.% of Si 3 N 4 Whisker, 5 to 15wt.% of Si powder, polyvinyl alcohol PVA as a dispersant and polyethylene glycol-400 as a wetting agent, wherein the PVA is 0.5 to 0.8 wt%, and the polyethylene glycol-400 is 1.2 to 1.7wt.% are dissolved in deionized water, 2.5 to 4.5wt.% of HCl is added, the pH value is adjusted to be 1 to 3, and the mixture is subjected to ball milling and dispersion for 1 to 6 hours; then adding 5-8 wt.% of acrylamide AM and 0.3-0.5 wt.% of N, N-methylene bisacrylamide MBAM, and performing ball milling dispersion for 0.5-4 hours to obtain slurry;
step 2, injection molding and curing: adding 0.3-0.45 wt.% of ammonium persulfate APS (ammonium persulfate per second) into the slurry as an initiator, removing bubbles in vacuum for 5-10 min, stirring, then carrying out injection molding, vibrating to remove bubbles, and then crosslinking and curing the slurry at 60-90 ℃ to obtain a ceramic wet blank;
step 4, glue discharging treatment: placing the dried ceramic biscuit in a muffle furnace, heating to 400-600 ℃ at the speed of 0.5-2 ℃/min, and preserving heat for 1-4 h to obtain porous Si 3 N 4w a/Si preform;
step 5, in-situ nitridation: porous Si 3 N 4w the/Si preform is placed in a nitriding furnace in N 2 Heating to 1400-1500 deg.c at 1-5 deg.c/min in atmosphere, maintaining for 1-4 hr to react Si powder to produce silicon nitride matrix, filling the pores and obtain Si powder 3 N 4w /Si 3 N 4 A composite material.
And the oscillation defoaming time in the step 2 is 5-10 min.
And (3) naturally drying for 24-72 h at room temperature.
Advantageous effects
The invention provides Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method of making a composite material, si 3 N 4 Preparing the crystal whisker and the Si powder into a ceramic wet blank by gel casting one-step molding, drying and then adopting low-temperature air firing to discharge gel to obtain porous Si 3 N 4w a/Si preform; porous Si 3 N 4w Putting the/Si prefabricated body into a nitriding furnace, and introducing N 2 Nitriding the Si powder in the preform to form Si 3 N 4 In-situ forming silicon nitride on the whisker to obtain Si 3 N 4w /Si 3 N 4 A composite material. The invention takes hydrochloric acid as a pH regulator, innovatively introduces Si powder and Si under acidic condition 3 N 4 The forming of the whisker preform is combined, so that the stability of micron-sized Si powder with higher specific surface area in water-based slurry is improved; simultaneously, the polyvinyl alcohol (PVA) is taken as a dispersant, thereby realizing the Si 3 N 4 Stable dispersion of whiskers in acidic slurry to obtain Si 3 N 4w Si complexThe high volume fraction synergistically stabilizes the slurry in suspension. The volume of the Si powder expands in the nitridation reaction process, so that the pores in the prefabricated body can be effectively occupied, and the shrinkage of the blank body is reduced; and the in-situ reaction does not change the distribution of Si, so that a silicon nitride substrate with uniform distribution can be obtained, and the crystal whisker bearing is facilitated. The method developed by the invention is suitable for preparing large-size complex-shaped components, and the high-performance ceramic matrix composite material with isotropy and smaller residual stress can be obtained by combining gel casting with in-situ reaction.
In order to solve the problem that the low-particle-size Si powder cannot be stably dispersed in the conventional gel-casting alkaline slurry, the invention provides an acidic slurry with the pH value less than 7, and polyvinyl alcohol (PVA) is used as a dispersing agent, so that the suspension stable dispersion of the high-volume-fraction silicon nitride whiskers and the low-particle-size Si powder multiphase particles with the particle size of less than 10 mu m is realized.
In order to solve the problems of more holes and cracks, uneven distribution and the like of a PIP/CVI silicon nitride substrate when a composite material is prepared by combining a gel casting process with a PIP/CVI process, the method utilizes Si powder in-situ nitridation reaction to uniformly occupy the holes of a ceramic blank and effectively reduces the stress in the composite material.
In order to solve the problem of complex process flow caused by that when a composite material is prepared by combining gel casting with PIP/CVI technology, firstly forming a whisker preform, and then preparing a substrate step by step and for many times by a CVI or PIP method, the invention provides that Si powder is added in the forming process of a silicon nitride whisker preform, and the two processes of forming the preform and preparing the substrate are highly combined, so that the process steps of the composite material are obviously simplified, and the manufacturing period is shortened.
Si provided by the invention 3 N 4w /Si 3 N 4 The preparation method of the composite material has the beneficial effects that:
1. si prepared by the invention 3 N 4w /Si 3 N 4 The composite material has excellent mechanical, wave-transmitting, high-temperature and environmental properties and good comprehensive performance, and can meet the high-performance requirements of high-altitude Wen Toubo parts of a hypersonic aircraft radome on the material.
2. Si according to the invention 3 N 4w /Si 3 N 4 The preparation method of the composite material can obtain the high-performance ceramic matrix composite material with isotropy and small residual stress, and is suitable for manufacturing large-size components with complex shapes.
3. Si according to the invention 3 N 4w /Si 3 N 4 The preparation method of the composite material comprises the step of introducing reaction source Si powder of a silicon nitride substrate in the composite material into Si in advance 3 N 4 In the whisker preform, the preparation process of the composite material matrix is simplified, the process complexity is reduced, and the preparation period is greatly shortened.
4. Si according to the invention 3 N 4w /Si 3 N 4 The slurry of the composite material preparation method takes HCl as a pH regulator, thereby realizing the stable dispersion of Si powder with the particle size of less than 10 mu m, improving the volume fraction of solid phase in gel casting slurry, not only effectively improving the strength of a blank body and ensuring the integrity of the blank body, but also reducing the volume shrinkage and residual stress in the drying process of the blank body and being beneficial to the mechanical property of the composite material.
5. Si according to the invention 3 N 4w /Si 3 N 4 The preparation method of the composite material can adjust Si in the slurry 3 N 4 The proportion of the crystal whiskers and the Si powder realizes the design of a pore structure of the prefabricated body, the content and the distribution of two phases can be regulated, more space is provided for the collaborative design of the mechanics and the wave-transmitting performance of the composite material, the requirements under different conditions can be met, and the customized design is hopeful to be realized.
6. Si according to the invention 3 N 4w /Si 3 N 4 According to the preparation method of the composite material, the Si powder is subjected to nitridation reaction to increase weight, and the volume is expanded in the reaction process. The generated silicon nitride substrate can copy the distribution of Si powder in a preform, or uniformly grow on the lap joint of the whiskers to strengthen the preform, or form holes among the whiskers and the surface of the whiskers, effectively fill ceramic pores to play a role in densification, and is favorable for improving the material performance.
Drawings
FIG. 1 is a process flow diagram of the present invention
FIG. 2 is a preparation of example 1 of the present inventionSi of (2) 3 N 4w Macroscopic photograph of/Si preform
FIG. 3 is Si prepared according to example 1 of the present invention 3 N 4w Scanning Electron Microscope (SEM) picture of/Si preform degumming rear section
FIG. 4 shows Si prepared in example 1 of the present invention 3 N 4w /Si 3 N 4 Scanning Electron Microscope (SEM) photograph of composite section
FIG. 5 shows Si prepared in example 1 of the present invention 3 N 4w Si preform and Si 3 N 4w /Si 3 N 4 X-ray diffraction (XRD) patterns of composite materials
Detailed Description
The invention will now be further described with reference to the following examples and drawings:
si provided by the invention 3 N 4w /Si 3 N 4 A preparation method of a composite material, in particular to gel casting Si 3 N 4w After the/Si preform, at high temperature N 2 Nitriding reaction of Si is carried out in an atmosphere to generate a silicon nitride substrate in situ, thereby obtaining Si 3 N 4w /Si 3 N 4 A method of compounding a material. The invention can prepare Si with isotropic characteristic, excellent mechanical property and wave-transmitting property 3 N 4w /Si 3 N 4 The composite material solves the problems of complex preparation process, large residual stress, more defects of prepared matrix and uneven distribution of the existing whisker reinforced ceramic matrix composite material.
Example 1.
Step one, preparing slurry:
in this example, si having a diameter of 0.5 to 1 μm and an aspect ratio of about 5 to 10 is used 3 N 4 Crystal whisker and Si powder with the grain diameter of 1-10 mu m. Adding Si into a ball milling tank 3 N 4 25.27g of whiskers and 2.10g of Si powder, then adding 0.6g of polyethylene glycol-400, 0.28g of polyvinyl alcohol, 1.5g of concentrated hydrochloric acid and 16.79g of deionized water, and carrying out ball milling for 4 hours. 2.72g of acrylamide and 0.18g of N, N-methylenebisacrylamide were then added and the ball milling was continued for 1 hour.
Step two, injection molding and curing:
and (3) fully dissolving 0.15g of ammonium persulfate in 1.5g of deionized water, adding the solution into the slurry obtained in the step one, removing bubbles in vacuum for 3min, circulating for 3 times, uniformly stirring, then carrying out injection molding, vibrating for 5min to remove bubbles, and then crosslinking and curing the slurry at 80 ℃.
Step three, demolding and drying:
and (3) after the slurry is completely gelatinized, demolding to obtain a ceramic wet blank, and naturally drying the obtained wet blank in the air for 48 hours to obtain a ceramic biscuit.
Step four, glue discharging treatment:
putting the ceramic biscuit obtained in the third step into a muffle furnace, heating to 600 ℃ at the speed of 1 ℃/min, and preserving the temperature for 2h to obtain Si shown in figure 2 3 N 4w The surface of the/Si prefabricated body is smooth and complete and has no crack; as shown in FIG. 3, the Si powder can be observed to be uniformly distributed on the lapping part of the whisker, the hole between the whiskers and the surface of the whisker on the section of the crystal under a scanning electron microscope.
Step five, in-situ nitridation:
putting the prefabricated body obtained in the fourth step into a nitriding furnace, and performing N reaction 2 Heating to 1450 deg.C at a rate of 5 deg.C/min in atmosphere, and maintaining for 2h to allow Si powder in the preform to react sufficiently to obtain Si 3 N 4w /Si 3 N 4 The fracture of the composite material is observed, and as shown in fig. 4, the generated silicon nitride matrix duplicates the distribution of Si powder in the prefabricated body, uniformly grows at the lap joint of the whisker, reinforces the prefabricated body of the whisker, and simultaneously plays a certain role in densifying the matrix distributed in the holes among the whiskers and the surface of the whisker. Comparative analysis of XRD results of the materials before and after the reaction in FIG. 5 revealed that Si was completely converted to Si 3 N 4 。
Example 2.
Step one, preparing slurry:
in this example, si having a diameter of 0.5 to 1 μm and an aspect ratio of about 5 to 10 is used 3 N 4 Crystal whisker and Si powder with the grain diameter of 1-10 mu m. Adding Si into a ball milling tank 3 N 4 23.40g of whisker and 3.50g of Si powder, then adding 0.6g of polyethylene glycol-400, 0.28g of polyvinyl alcohol, 1.5g of concentrated hydrochloric acid and 16.79g of deionized water, and ball-millingAnd 4h. 2.72g of acrylamide and 0.18g of N, N-methylenebisacrylamide were then added and the ball milling was continued for 1 hour.
Step two, injection molding and curing:
and (3) fully dissolving 0.15g of ammonium persulfate in 1.5g of deionized water, adding the solution into the slurry obtained in the step one, removing bubbles in vacuum for 3min, circulating for 3 times, uniformly stirring, then carrying out injection molding, vibrating for 5min to remove bubbles, and then crosslinking and curing the slurry at 80 ℃.
Step three, demolding and drying:
and (3) after the slurry is completely gelatinized, demolding to obtain a ceramic wet blank, and naturally drying the obtained wet blank in the air for 48 hours to obtain a ceramic biscuit.
Step four, glue discharging treatment:
putting the ceramic biscuit obtained in the third step into a muffle furnace, heating to 600 ℃ at the speed of 1 ℃/min, and preserving heat for 2h to obtain Si 3 N 4w a/Si preform.
Step five, in-situ nitridation:
putting the prefabricated body obtained in the fourth step into a nitriding furnace, and performing N reaction 2 Heating to 1450 deg.C at a rate of 5 deg.C/min in atmosphere, and maintaining for 2h to allow Si powder in the preform to react sufficiently to obtain Si 3 N 4w /Si 3 N 4 A composite material.
Example 3.
Step one, preparing slurry:
in this example, si having a diameter of 0.5 to 1 μm and an aspect ratio of about 5 to 10 is used 3 N 4 Crystal whisker and Si powder with the grain diameter of 1-10 mu m. Adding Si into a ball milling tank 3 N 4 18.72g of whisker and 6.99g of Si powder, then 0.6g of polyethylene glycol-400, 0.28g of polyvinyl alcohol, 1.5g of concentrated hydrochloric acid and 16.79g of deionized water are added, and ball milling is carried out for 4 hours. 2.72g of acrylamide and 0.18g of N, N-methylenebisacrylamide were then added and the ball milling was continued for 1 hour.
Step two, injection molding and curing:
and (3) fully dissolving 0.15g of ammonium persulfate in 1.5g of deionized water, adding the solution into the slurry obtained in the step one, removing bubbles in vacuum for 3min, circulating for 3 times, uniformly stirring, then carrying out injection molding, vibrating for 5min to remove bubbles, and then crosslinking and curing the slurry at 80 ℃.
Step three, demolding and drying:
and (3) after the slurry is completely gelatinized, demoulding to obtain a ceramic wet blank, and naturally drying the obtained wet blank in the air for 48 hours to obtain a ceramic biscuit.
Step four, glue discharging treatment:
putting the ceramic biscuit obtained in the third step into a muffle furnace, heating to 600 ℃ at the speed of 1 ℃/min, and preserving heat for 2h to obtain Si 3 N 4w a/Si preform.
Step five, in-situ nitridation:
placing the preform obtained in the fourth step in a nitriding furnace in N 2 Heating to 1450 deg.C at a rate of 5 deg.C/min in atmosphere, and maintaining for 2h to allow Si powder in the preform to react sufficiently to obtain Si 3 N 4w /Si 3 N 4 A composite material.
Claims (3)
1. By using Si 3 N 4w Preparation of Si from Si preform 3 N 4w /Si 3 N 4 A method of compounding materials, characterized by: the components of the Si3N4w/Si preform are Si powder and Si3N4 crystal whisker with the volume ratio of 1:2-10, wherein: the grain size of the Si powder is 1-10 mu m, and the length-diameter ratio of the crystal whisker is 5-20;
the method comprises the following steps:
step 1, preparing slurry: 40 to 55wt.% of Si 3 N 4 Dissolving crystal whiskers, 5-15 wt.% of Si powder, 0.5-0.8 wt.% of dispersing agent polyvinyl alcohol (PVA), 1.2-1.7 wt.% of wetting agent polyethylene glycol-400 in deionized water, adding 2.5-4.5 wt.% of hydrochloric acid (HCl), adjusting the pH value to 1-3, and performing ball milling dispersion for 1-6 hours; then adding 5-8 wt.% of acrylamide AM and 0.3-0.5 wt.% of N, N-methylene bisacrylamide MBAM, and performing ball milling dispersion for 0.5-4 hours to obtain slurry;
step 2, injection molding and curing: adding 0.3-0.45 wt.% of ammonium persulfate APS (ammonium persulfate solution) serving as an initiator into the slurry, removing bubbles in vacuum for 5-10 min, stirring, then carrying out injection molding, vibrating to remove bubbles, and then crosslinking and curing the slurry at 60-90 ℃ to obtain a wet ceramic blank;
step 3, demolding and drying: demoulding the cured ceramic wet blank, and naturally drying at room temperature;
step 4, glue discharging treatment: placing the dried ceramic biscuit in a muffle furnace, heating to 400-600 ℃ at the speed of 0.5-2 ℃/min, and preserving heat for 1-4 h to obtain porous Si 3 N 4w a/Si preform;
step 5, in-situ nitridation: porous Si 3 N 4w the/Si preform is placed in a nitriding furnace in N 2 Heating to 1400-1500 deg.c at 1-5 deg.c/min in atmosphere, maintaining for 1-4 hr to react Si powder to produce silicon nitride matrix, filling the pores and obtain Si powder 3 N 4w /Si 3 N 4 A composite material.
2. The method of claim 1, wherein: and the oscillation defoaming time in the step 2 is 5-10 min.
3. The method of claim 1, wherein: and (3) naturally drying for 24-72 h at room temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110570198.7A CN113248263B (en) | 2021-05-25 | 2021-05-25 | Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method for compounding materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110570198.7A CN113248263B (en) | 2021-05-25 | 2021-05-25 | Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method for compounding materials |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113248263A CN113248263A (en) | 2021-08-13 |
| CN113248263B true CN113248263B (en) | 2022-11-22 |
Family
ID=77184301
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110570198.7A Active CN113248263B (en) | 2021-05-25 | 2021-05-25 | Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method for compounding materials |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113248263B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115368161B (en) * | 2022-05-14 | 2023-10-13 | 西北工业大学 | Silicon nitride foam ceramic with multilevel structure and preparation method of silicon-impregnated nitriding in-situ growth whisker or nanowire bonding CVI (chemical vapor infiltration) process |
| CN115073195B (en) * | 2022-06-05 | 2023-04-18 | 西北工业大学 | Silicon nitride whisker reinforced nitride composite material for 3D printing radar antenna housing and preparation and printing methods |
| DE102023103508A1 (en) | 2023-02-14 | 2024-08-14 | Rogers Germany Gmbh | Method for producing a metal-ceramic substrate and a metal-ceramic substrate produced by such a method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110156484A (en) * | 2019-05-13 | 2019-08-23 | 西北工业大学 | A kind of BN/Si3N4Whisker preform and the preparation method for using gel casting forming |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4978643A (en) * | 1987-04-09 | 1990-12-18 | Ceramics Process Systems Corporation | Forming whisker reinforced sintered ceramics with polymerizable binder precursors |
| SE511312C2 (en) * | 1997-12-22 | 1999-09-06 | Sandvik Ab | Ways to manufacture whisker reinforced ceramics |
| CN1092170C (en) * | 1999-12-22 | 2002-10-09 | 中国科学院上海硅酸盐研究所 | Process for preparing biscuit of ceramics by reaction induced gelatination |
| CN107698271B (en) * | 2017-09-11 | 2020-11-06 | 西北工业大学 | High-temperature-resistant high-strength and high-toughness silicon nitride-based wave-transparent composite material and preparation method thereof |
| CN108017405A (en) * | 2017-11-22 | 2018-05-11 | 马鞍山科润冶金材料有限公司 | A kind of preparation method of In-situ Mullite Whisker ceramic material |
| CN109320276B (en) * | 2018-10-15 | 2021-04-02 | 西北工业大学 | Preparation method of silicon nitride whisker and silicon nitride nanowire reinforced silicon nitride-based wave-transmitting ceramic |
| CN111320484B (en) * | 2020-04-01 | 2022-10-14 | 西北工业大学 | Preparation method of isotropic silicon nitride crystal whisker reinforced nitride composite material antenna housing |
| CN112279670A (en) * | 2020-11-10 | 2021-01-29 | 衡阳凯新特种材料科技有限公司 | Low-shrinkage porous silicon nitride ceramic and preparation method thereof |
-
2021
- 2021-05-25 CN CN202110570198.7A patent/CN113248263B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110156484A (en) * | 2019-05-13 | 2019-08-23 | 西北工业大学 | A kind of BN/Si3N4Whisker preform and the preparation method for using gel casting forming |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113248263A (en) | 2021-08-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113248263B (en) | Si 3 N 4w Si preform and preparation of Si using the same 3 N 4w /Si 3 N 4 Method for compounding materials | |
| CN111777427B (en) | Preparation method of nacre-like layered high-strength super-tough ceramic | |
| CN107698271B (en) | High-temperature-resistant high-strength and high-toughness silicon nitride-based wave-transparent composite material and preparation method thereof | |
| CN110093588B (en) | Fine-grain aluminum-scandium alloy target material and preparation method and application thereof | |
| WO2022222778A1 (en) | Fine ceramic material formed by means of ceramic precursor framework and preparation method therefor and use thereof | |
| CN109970439B (en) | Preparation method of light ceramic composite sheet | |
| CN108484173B (en) | SiCf/SiC composite material and preparation method thereof | |
| CN112645729B (en) | High-temperature-resistant zirconia composite heat-insulating material with mesoporous structure and preparation method thereof | |
| CN114773082B (en) | Silicon nitride ceramic radome with symmetrical continuous gradient structure and preparation method thereof | |
| CN114804912A (en) | Method for preparing high-toughness high-temperature-resistant directionally-arranged silicon nitride monolithic porous ceramic | |
| CN109320257B (en) | Preparation method of high-strength high-porosity porous silicon nitride ceramic | |
| CN108178636B (en) | Si3N4/SiC composite wave-absorbing ceramic and preparation method thereof | |
| CN112645713B (en) | High-strength and high-toughness ceramic composite material and preparation method thereof | |
| CN117534495A (en) | Method for preparing ceramic matrix composite by combining precursor dipping, cracking and reaction infiltration | |
| CN109761623B (en) | Preparation method and application of organic-deposition-phase-free 3D printing silicon oxynitride ink | |
| CN115073195B (en) | Silicon nitride whisker reinforced nitride composite material for 3D printing radar antenna housing and preparation and printing methods | |
| CN116573952A (en) | Adhesive jet printing silicon carbide-aluminum composite material and preparation method thereof | |
| CN112898040B (en) | Method for preparing intercrystalline-free glass phase beta-Si by using high length-diameter ratio whisker3N4Method for producing porous ceramics | |
| CN115196976A (en) | Gradient porous ceramic and preparation method thereof | |
| CN114195538A (en) | Preparation method of compact hexagonal boron nitride ceramic material | |
| CN114349516A (en) | Method for synthesizing high-density SiC ceramic at low temperature | |
| CN109627691B (en) | Preparation method of silicon carbide/epoxy resin composite material | |
| CN118084498B (en) | Forming method of silicon carbide ceramic wafer boat | |
| CN111470866A (en) | Diamond-silicon carbide composite material, preparation method thereof and electronic equipment | |
| CN115974578B (en) | alpha-SiAlON porous ceramic and preparation method and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |