CN108558423B

CN108558423B - Preparation method of low-oxygen-content continuous silicon carbide fiber reinforced Ni-Al/SiCp ceramic matrix composite

Info

Publication number: CN108558423B
Application number: CN201810428337.0A
Authority: CN
Inventors: 罗瑞盈; 侯敏敏
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2018-05-07
Filing date: 2018-05-07
Publication date: 2020-09-15
Anticipated expiration: 2038-05-07
Also published as: CN108558423A

Abstract

The invention relates to a continuous silicon carbide fiber reinforced Ni-Al/SiC with low oxygen content_pA method for preparing a ceramic matrix composite. Taking a silicon carbide fiber preform with low oxygen content as a reinforced framework and taking SiC_pThe main matrix is Al alloy and Ni powder are used as plasticizing phases; concretely, mixing silicon carbide powder, aluminum alloy powder, nickel powder, chromium powder and a dispersing agent, and carrying out ball milling; placing the preform formed by needling into a graphite sintering mold, paving mixed powder on the upper surface and the lower surface of the preform, then carrying out high-temperature vacuum infiltration, obtaining a preformed sample, and carrying out pre-oxidation treatment; and repeating the steps until the weight gain of two adjacent preformed samples is less than 1 percent, thereby obtaining the compact ceramic matrix composite material. Silicon carbide fiber reinforced Ni-Al/SiC prepared by the invention_pThe ceramic matrix composite has the advantages of uniform microstructure, compact structure, good interface bonding, greatly improved strength and fracture toughness, and good high-temperature oxidation resistance and corrosion resistance.

Description

Preparation method of low-oxygen-content continuous silicon carbide fiber reinforced Ni-Al/SiCp ceramic matrix composite

Technical Field

The present invention relates to SiC_fThe field of/SiC ceramic matrix composite materials, in particular to a continuous silicon carbide fiber reinforced Ni-Al/SiC with low oxygen content_pA method for preparing a ceramic matrix composite.

Background

SiC_fThe SiC ceramic matrix composite material has great attention because of the excellent oxidation resistance, can meet the requirements of long-term use, light weight and high temperature resistance of an aeroengine, and becomes a preferred material of an engine with a high thrust-weight ratio. However, in aircraft engines, combustion of the fuel produces a large amount of corrosive products, such as high temperature, high pressure steam, molten salt impurities (alkali salts such as Na, Cl, S), etc., and thus SiC_fthe/SiC ceramic matrix composite has the problems of molten salt corrosion and water vapor corrosion in a gas environment.

SiC produced by CVI_fThe raw material trichloromethylsilane prepared from the SiC ceramic matrix composite material has strong corrosivity, high flammability and low effective utilization rate of the raw material, and the trichloromethylsilane has irritation to skin and eyes, and tail gas discharged in the preparation process pollutes the environment; and SiC prepared by CVI method_fthe/SiC composite material has the defects of long process preparation period and high cost. And SiC is prepared by a precursor polycarbosilane impregnation cracking process (PIP)_fSilicon carbide fiber seriously damaged in the process of the/SiC composite materialA problem; and the cost for preparing the raw material polycarbosilane is relatively high, and a dissolving agent xylene is inflammable and has pungent smell.

Ni-Al/SiC_pThe ceramic matrix composite has the advantages of small thermal expansion coefficient, high thermal conductivity, good dimensional stability, high specific strength, wear resistance, excellent corrosion resistance and the like, has wide application space in the aspects of aviation, aerospace structural members, automobile members and the like, and is one of the materials with the widest potential application prospect. The method finds that the aluminum alloy liquid has good wettability to SiC within the temperature range of 1150-1350 ℃ by venenin and the like, SiC powder with different finenesses is made into a blank body, and the blank body is directly oxidized on the surface of the aluminum alloy liquid without heat treatment, so that near-net reinforced SiC/Al can be obtained₂O₃The Al-Si alloy composite material. The material has excellent corrosion resistance and scouring resistance, and optimal high-temperature stability and mechanical properties.

The SiC ceramic fiber is widely applied to the high-technology fields of missiles, spaceflight, atomic energy and the like due to the characteristics of high temperature resistance, oxidation resistance, corrosion resistance, aging resistance, excellent mechanical property and the like. The preparation of SiC ceramic fiber by organic polymer precursor conversion method is a hot spot in the research field of ceramic matrix composite materials. The production of silicon carbide fibers has been industrialized, but there is a large gap between the practical application temperature and the theoretical application temperature of silicon carbide fibers. The current Nicalon type silicon carbide fiber can be used at a high temperature of 1200 ℃, but the requirements of various high-technology fields on the use temperature and the environment are more and more strict, and the temperature still can not reach the requirements. The research of the foreign Rachman C and the like on the silicon carbide fiber shows that the root cause of the reduction of the high-temperature mechanical property is the existence of oxygen. Oxygen forms an amorphous Si-C-O structure with Si and C in the fiber, and the fiber generates a thermal decomposition reaction of escaping small molecules at high temperature, so that the chain structure of the fiber is broken, the molecular chain is shortened, and the connection between the chains is damaged; on the other hand, the fiber is obviously weightless, and porous structural defects are generated on the surface and in the interior. Based on this, it is very important to find a new method for preparing ceramic matrix composite.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the continuous silicon carbide fiber reinforced Ni-Al/SiC with low oxygen content_pA method for preparing a ceramic matrix composite. The Ni-Al/SiC provided by the invention_pThe ceramic matrix composite has excellent high-temperature oxidation resistance and corrosion resistance, and effectively overcomes the defects of the traditional SiC_fThe oxidation corrosion of the matrix under the environment of the SiC ceramic matrix composite engine.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

in a first aspect, the present invention provides a method for preparing a ceramic matrix composite material, comprising the steps of: s101: selecting silicon carbide fibers with high strength, high hardness, good toughness and low oxygen content, carrying out needling forming by using a three-dimensional needling technology, reinforcing the silicon carbide fibers in the plane direction, combining a silicon carbide net tire as interlayer filling, increasing layer by layer, and needling layer by layer to obtain a silicon carbide fiber laminated three-dimensional needling preform; s102: elutriating SiC powder by using deionized water until the deionized water is completely clear, and drying the elutriated SiC powder; carrying out high-temperature pre-oxidation on the dried SiC powder to form compact SiO on the surface₂Layer, then cooling to room temperature; uniformly mixing Ni powder, aluminum alloy powder, a dispersing agent and the oxidized SiC powder, and then carrying out vacuum drying to obtain mixed powder; s103: ultrasonically cleaning and drying a laminated three-dimensional needling preform of silicon carbide fibers, putting the preform formed by needling into a graphite sintering mold by adopting a vacuum pressureless infiltration method, and paving mixed powder with a preset thickness on the upper surface and the lower surface of the preform; then adding a Cr powder additive, enabling the chromium powder and the mixed powder in S102 to be uniform, immersing and embedding the preform formed by needling, enabling the preform to be in uniform contact, then carrying out high-temperature vacuum infiltration, cooling a product obtained after the high-temperature vacuum infiltration to room temperature, and demoulding to obtain the silicon carbide fiber reinforced Ni-Al/SiC fiber reinforced composite material_pA ceramic matrix composite preform sample; s104: pre-oxidizing the pre-formed sample obtained in the step S103, polishing, washing and drying to obtain pre-oxidized silicon carbide fiber reinforced Ni-Al/SiC_pA ceramic matrix composite preform sample; s105: subjecting the preform obtained in S104 toPutting the product into a graphite sintering mold again, repeating the operations of S103 and S104 until the weight gain of two adjacent preformed samples is less than 1%, and finally obtaining the compact continuous silicon carbide fiber reinforced Ni-Al/SiC_pA ceramic matrix composite.

Preferably, in S101: the density of the silicon carbide fiber laminated three-dimensional needling preform is 0.2-0.6 g/cm³The needling density is 5 to 45 needles/cm²The interlayer density is 1-20 layers/10 mm; the silicon carbide fiber with high strength, high hardness, good toughness and low oxygen content is specifically as follows: the content of Si is 56-60 wt%, the content of C is 30-40 wt%, the content of O is 3-5 wt%, the average diameter is 10-15 μm, the tensile strength is 2-3 GPa, and the Young modulus is 200-240 GPa.

Preferably, in S102: the method for elutriating the SiC powder by using the deionized water specifically comprises the following steps: ultrasonically treating SiC powder in deionized water for 15-30 min, standing for 10-25 min, removing fine SiC particles suspended in the deionized water, filtering, collecting a solid phase, and repeatedly elutriating for 3-5 times; in the elutriated SiC powder, the average grain diameter of the SiC powder is 14-30 mu m, and the purity is more than 99.9%; drying the washed SiC powder for 10-15 h at 110-120 ℃; the high-temperature pre-oxidation specifically comprises the following steps: roasting the dried SiC at the high temperature of 800-850 ℃ for 0.5-1.5 h, and then preserving heat at the temperature of 280-310 ℃ for 3-5 h; the temperature of vacuum drying is 40-50 ℃, and the time is 10-15 h.

Preferably, in S102: uniformly mixing Ni powder, aluminum alloy powder, a dispersing agent and the oxidized SiC powder in a high-energy ball mill; wherein the mass ratio of the SiC powder, the Ni powder and the aluminum alloy powder is (50-70): (10-15): (30-50), the ball milling rotating speed is 300-450 r/min, and the time is 8-10 h; the grain size of the aluminum alloy powder is 10-20 mu m, and the aluminum alloy component contains 7-15% of Si, 6-10% of Mg and the balance of Al; the particle size of the Ni powder is 40-50 mu m, and the purity is more than 99.9%.

Preferably, in the ball milling process, the milling balls are Al₂O₃The diameter of the hard alloy is 6-15 mm; wherein, the powder lot: grinding balls: 1 (3-6) and (0.8-1.2), wherein the dispersant is a mixed solution of polyethylene glycol and ethanolIn the liquid, the mass fraction of the polyethylene glycol is 3-5%.

Preferably, in S103: presetting the thickness to be 6-10 mm, wherein the addition amount of the Cr powder additive is 1-5%, and immersing and embedding the preform formed by needling uniformly by the chromium powder and the mixed powder in the S102 to make the preform uniformly contact; the high-temperature vacuum infiltration specifically comprises: filling nitrogen protection in a high-temperature vacuum furnace with the absolute vacuum degree of 5-50 Pa, infiltrating at 1100-1350 ℃, and preserving heat for 2-2.5 hours to enable the Al alloy to be melted and infiltrated into the preform; cooling the product after the high-temperature vacuum infiltration to room temperature specifically comprises the following steps: when the temperature is higher than 900 ℃, the cooling rate is 3-5 ℃/min; and then preserving the heat at 900 ℃ for 30min, and cooling to room temperature at a cooling rate of 5-10 ℃/min.

Preferably, in the impregnation process, the temperature rise rate is 5-15 ℃/min, and the flow rate of nitrogen is 60-120 mL/min.

Preferably, in S104: the pre-oxidation treatment is carried out in a tube furnace, and the specific conditions comprise: putting the preformed sample into a tube furnace, heating to 660-700 ℃, and heating to O₂Preserving heat for 3-5 h under the atmosphere; and the drying temperature is 80-120 ℃, and the drying time is 1-2 h.

In a second aspect, the continuous silicon carbide fiber reinforced Ni-Al/SiC prepared by the method provided by the invention_pA ceramic matrix composite.

Compared with the prior art, the invention has the following beneficial effects:

(1) the Ni-Al/SiC provided by the invention_pThe ceramic matrix composite has excellent high-temperature oxidation resistance and corrosion resistance, and effectively overcomes the defects of the traditional SiC_fThe oxidation corrosion of the matrix under the environment of the SiC ceramic matrix composite engine.

(2) The pressureless infiltration method adopted by the invention has the advantages of simple process method, convenient operation, capability of manufacturing complex components in a near-size forming way and the like.

(3) With conventional SiC_fCompared with the SiC ceramic matrix composite material, the silicon carbide fiber reinforced Ni-Al/SiC prepared by the invention_pThe ceramic matrix composite has uniform microstructure, greatly improved strength and fracture toughness, and oxygen content of 3 to up to5 wt%, bending strength of 400-500 MPa, and fracture toughness of 15-18 MPa.m^1/2The density of the material can reach 96-98.5%, and the thermal expansion coefficient is as low as 8-10 × 10^-6and/K. More importantly, the adoption of the low-oxygen SiC fiber can well improve the high-temperature long-time oxidation resistance of the material.

(4) The SiC powder is uniformly distributed in the matrix, and the phenomenon of particle agglomeration is avoided. The microstructure with uniformly distributed particles is beneficial to relieving stress concentration of the composite material during bearing, thereby being beneficial to load transfer and improving the Ni-Al/SiC_pMechanical properties of the base composite material.

(5) The composite material prepared by impregnating the aluminum alloy containing magnesium has high density and low porosity. Mg can play a role of a permeation aid in the infiltration process, so that the wettability of SiC reinforced particles and Al alloy is improved; meanwhile, Si can effectively inhibit Al₄C₃And the infiltration process can be promoted, so that the prepared composite material has high densification degree and better quality. When the SiC particles are in contact with the molten aluminum, they are actually SiO₂Directly contacts with aluminum liquid to generate Al with high melting point₂O₃。A1₂O₃The ceramic is one of the most widely used ceramic materials at present, has the advantages of high temperature resistance, high wear resistance, corrosion resistance, oxidation resistance, low density and the like, has a melting point higher than 2200K, and is a high-temperature structural material with a good application prospect. Meanwhile, the preoxidation of SiC for sufficient time increases SiO on the surface of SiC particles₂The thickness of the film, Mg in the alloy can form dense MgAl on the surface of SiC particles through interface reaction₂O₄Particles which, like the coating on SiC particles, are effective in protecting SiC from Al₄C₃Is performed. Spinel (i.e. MgAl)₂O₄) The particles being grown attached to the SiC surface, MgAl₂O₄the/SiC belongs to a semi-coherent interface, and the interface bonding is good, which is good for the mechanical property of the prepared composite material.

(6) Oxygen in the air enters NiO generated by reaction with Ni through diffusion to react with Al to generate Al with high melting point₂O₃With Ni, the content of residual metal Al can be reduced and increasedHigh temperature performance of the composite.

(7) Compared with the traditional SiC_fThe preparation method of the SiC ceramic matrix composite mainly adopts cheap SiC powder, Ni powder and Al alloy powder as raw materials, and has the advantages of simple preparation process, low cost, no corrosion to equipment and no pollution to the environment; and the material is formed in a near size, so that the processing cost of the material can be effectively reduced.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a flow chart of a method for preparing a ceramic matrix composite according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.

The experimental procedures in the following examples are conventional unless otherwise specified. In the quantitative experiments in the following examples, three replicates were set up, and the data are the mean or mean ± standard deviation of the three replicates. The performance parameters of the SiC powder used in the invention are shown in the following table:

material	Modulus of elasticity/GPa	Density (g.cm)^-3)	Coefficient of linear expansion/K^-1	Poisson ratio
					SiC	400～450	3.18～3.20	4.30×10^-6	0.17

The invention provides a continuous silicon carbide fiber reinforced Ni-Al/SiC with low oxygen content_pThe preparation method of the ceramic matrix composite material, as shown in figure 1, comprises the following steps:

the method comprises the following steps: preparation of laminated three-dimensional needling preform of silicon carbide fiber

Selecting silicon carbide fibers with high strength, high hardness, good toughness and low oxygen content, carrying out needling forming by using a three-dimensional needling technology, reinforcing the silicon carbide fibers in the plane direction, combining a silicon carbide net tire as interlayer filling, increasing layer by layer, and needling layer by layer to obtain the silicon carbide fiber laminated three-dimensional needling preform. Wherein the density of the silicon carbide fiber laminated three-dimensional needling preform is 0.2-0.6 g/cm³The needling density is 5 to 45 needles/cm²The density of the layers is 1 to 20 layers/10 mm.

Step two: preparation of the powder mixture

(1) Ultrasonically treating the SiC powder in deionized water for 15-30 min, standing for 10-25 min, pouring the deionized water together with the fine SiC particles suspended in the deionized water, and repeatedly elutriating for 3-5 times until the deionized water is completely clear; and (3) keeping the temperature of the washed SiC powder at 110-120 ℃ and drying for 10-15 h for later use.

(2) Roasting the dried SiC at 800-850 ℃ for 0.5-1.5 h, and then preserving heat at 280-310 ℃ for 3-5 h to preoxidize the SiC at high temperature to form a layer of compact SiO on the surface₂Layer, then cooled to room temperature.

(3) Mixing 50-70% of SiC powder, 10-15% of Ni powder, 30-50% of Al alloy powder and a dispersing agent after oxidation treatment, and placing the mixture in a high-energy ballAnd (3) carrying out dry milling for 8-10 h in a mill (the rotating speed is 300-450 r/min), using a milling ball to promote the raw material powder to be uniformly dispersed, and finally putting the ball-milled mixed powder into a vacuum drying oven at 40-50 ℃ for drying for 10-15 h at constant temperature. Specifically, in the ball milling process, the milling ball is Al₂O₃The diameter of the hard alloy is 6-15 mm; wherein the powder lot: grinding balls: the dispersant is 1 (3-6) and 0.8-1.2, the dispersant is a mixed solution of polyethylene glycol and ethanol, and the mass fraction of the polyethylene glycol in the mixed solution of the polyethylene glycol and the ethanol is 3-5%.

Step three: preparation of silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform sample

Ultrasonically cleaning and drying a silicon carbide fiber porous preform, putting the preform subjected to needle punching into a graphite sintering mold by adopting a vacuum pressureless infiltration method, paving mixed powder with the thickness of 6-10 mm on the upper surface and the lower surface of the preform, adding 1-5 w.t.Cr powder additive, uniformly immersing and embedding the preform subjected to needle punching into chromium powder and the mixed powder in S102, uniformly contacting the preform, and adding the chromium powder to facilitate grain refinement, increase uniform dispersibility of particles and improve plasticity of the material. Filling nitrogen into a high-temperature vacuum furnace with the absolute vacuum degree of 5-50 Pa for protection, infiltrating at 1100-1350 ℃, heating up at the rate of 5-15 ℃/min, and keeping the temperature for 2-2.5 h, so that Al alloy is melted and infiltrated into the preform and reacts with SiC powder and Ni powder introduced into the preform; and proper infiltration heat preservation time is carried out, which is beneficial to the tight combination between SiC particles and aluminum alloy and prevents Al₄C₃Generation of a harmful interface; then cooling to room temperature and demoulding to obtain the silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform samples. Wherein, the cooling to the room temperature specifically comprises the following steps: when the temperature is higher than 900 ℃, the cooling rate is 3-5 ℃/min; and then preserving the heat at 900 ℃ for 30min, and cooling to room temperature at a cooling rate of 5-10 ℃/min.

Step four: composite preform sample pre-oxidation

Putting the obtained preformed sample into a tube furnace, heating to 660-700 ℃, and carrying out O reaction₂Preserving heat for 3-5 h under atmosphere for pre-oxidation treatment toThoroughly eliminating the influence of the residual Al alloy powder on the high-temperature performance of the composite material; then polishing, washing, drying and drying at 80-120 ℃ for 1-2 h to obtain the preoxidized silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform samples.

Step five: preparation of dense continuous silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite

Putting the preformed sample obtained in the step S104 into a graphite sintering mold again, repeating the steps S103 and S104 until the weight gain of the preformed samples in two adjacent steps is less than 1%, and finally obtaining the compact continuous silicon carbide fiber reinforced Ni-Al/SiC_pA ceramic matrix composite.

In a further embodiment of the present invention, in S101, the silicon carbide fiber having high strength, high hardness, good toughness and low oxygen content is specifically: the content of Si is 56-60 wt%, the content of C is 30-40 wt%, the content of O is 3-5 wt%, the average diameter is 10-15 μm, the tensile strength is 2-3 GPa, and the Young modulus is 200-240 GPa. In other words, the low-oxygen content silicon carbide fiber used not only has excellent mechanical properties, but also has better high-temperature resistance.

In a further embodiment of the present invention, in S102, the average particle size of the SiC powder after the elutriation is 14 to 30 μm, and the purity is > 99.9%; the particle size of the aluminum alloy powder is 10-20 mu m, and the aluminum alloy contains 7-15% of Si, 6-10% of Mg and the balance of Al; the particle size of the Ni powder is 40-50 mu m, and the purity is more than 99.9%.

In a further embodiment of the present invention, in S103, during the ball milling process, the milling balls are Al₂O₃The diameter of the hard alloy is 6-15 mm; powder lot: grinding balls: the dispersant is 1, (3-6), (0.8-1.2), the dispersant is a mixed solution of polyethylene glycol and ethanol, and the mass fraction of the polyethylene glycol in the mixed solution of polyethylene glycol and ethanol is 3% -5%; in addition, the whole non-pressure infiltration process is carried out under the protection of flowing high-purity nitrogen with the volume percentage of 99.99 percent, and the flow rate of the nitrogen is 60-120 mL/min.

The present invention will be further described with reference to the following specific examples.

Example one

This example provides a low oxygen content continuous silicon carbide fiber reinforced Ni-Al/SiC_pThe preparation method of the ceramic matrix composite material comprises the following steps:

Selecting continuous silicon carbide fiber with low oxygen content, Si content of 59.73 wt%, C content of 35.28 wt%, O content of 3.78 wt%, average diameter of 10 mu m, tensile strength of 3GPa and Young modulus of 240GPa, carrying out needling forming by using a three-dimensional needling technology, reinforcing the silicon carbide fiber in the plane direction, combining a silicon carbide net tire as interlayer filling, increasing layer by layer, and needling layer by layer to obtain the silicon carbide fiber laminated three-dimensional needling preform. Wherein the density of the preform is 0.4g/cm³The needling density is 20 needles/cm²The interlayer density was 10 layers/10 mm.

Step two: preparation of the powder mixture

Weighing 140.4g of SiC powder with the average diameter of 14 mu m, 54g of aluminum alloy powder with the average diameter of 10 mu m and 21.6g of Ni powder with the average diameter of 40 mu m, wherein the mass fractions of the powder are 65%, 25% and 10%; weighing 1335g of Al with the diameter of 8mm₂O₃Grinding balls, wherein the ratio of the grinding balls to the mixed materials is 6: 1; taking 222.5g of mixed solution of polyethylene glycol and ethanol, wherein the mass fraction of the polyethylene glycol in the mixed solution is 3%, and the mass ratio of the mixed solution to the dispersing agent is 1: 1.

(1) Ultrasonically treating the SiC powder in deionized water for 20min, standing for 15min, pouring the deionized water together with the fine SiC particles suspended in the deionized water, and repeatedly elutriating for 3-5 times until the deionized water is completely clear; and (4) keeping the temperature of the washed SiC powder at 120 ℃ and drying for 12h for later use.

(2) Roasting the dried SiC powder at 800 ℃ for 1h, and then preserving heat at 300 ℃ for 3h to preoxidize the SiC at high temperature to form a layer of compact SiO on the surface₂Layer, then cooled to room temperature.

(3) Mixing 70% of SiC powder, 10% of Ni powder, 20% of Al-alloy powder and a dispersing agent after oxidation treatment, dry-milling the mixture in a high-energy ball mill (the rotating speed is 300r/min) for 8 hours, and promoting the raw material powder to be uniformly dispersed by using a grinding ball, wherein the powder comprises the following components in percentage by weight: grinding balls: dispersant 1:6: 1; and finally, placing the ball-milled mixed powder into a vacuum drying oven at 45 ℃ for constant-temperature drying for 12 hours.

Ultrasonically cleaning and drying a silicon carbide fiber porous preform, putting the preform subjected to needle punching forming into a graphite sintering mold by adopting a vacuum pressureless infiltration method, paving mixed powder with the thickness of 8mm on the upper surface and the lower surface of the preform, adding 6.48g of chromium powder additive, and immersing and embedding the preform subjected to needle punching forming uniformly by using the chromium powder and the mixed powder in S102 so as to enable the preform to be in uniform contact. Filling nitrogen into a high-temperature vacuum furnace with the absolute vacuum degree of 5Pa for protection, infiltrating at the temperature of 1100 ℃, heating at the rate of 5 ℃/min, keeping the temperature for 2h, enabling Al alloy to be melted and infiltrated into the preform, reacting with SiC powder and Ni powder introduced into the preform, cooling to room temperature, and demolding to obtain the silicon carbide fiber reinforced Ni-Al/SiC/fiber reinforced Ni-Al_pA ceramic matrix composite preform sample; proper infiltration and heat preservation time is carried out, which is beneficial to the tight combination between SiC particles and aluminum alloy and prevents Al₄C₃Generation of a harmful interface; then cooling to room temperature and demoulding to obtain the silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform samples. Wherein, the cooling to the room temperature specifically comprises the following steps: cooling at a rate of 3 deg.C/min before 900 deg.C, maintaining at 900 deg.C for 30min, and rapidly cooling to room temperature at 6 deg.C/min. The whole pressureless infiltration process is carried out under the protection of flowing high-purity nitrogen with the volume percentage of 99.99 percent, and the flow rate of the nitrogen is 100 mL/min.

Step four: composite preform sample pre-oxidation

Placing the obtained preformed sample into a tube furnace, heating to 700 ℃, and performing O₂Preserving heat for 3 hours in the atmosphere, and thoroughly eliminating the influence of residual Al alloy powder on the high-temperature performance of the composite material; then grinding, washing, drying and drying at 120 ℃ for 2h to obtain the preoxidized silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform samples.

Example two

Selecting low-oxygen-content continuous silicon carbide fibers with the Si content of 56.32 wt%, the C content of 39.13 wt%, the O content of 4.42 wt%, the average diameter of 15 mu m, the tensile strength of 2GPa and the Young modulus of 200GPa, carrying out needling forming by using a three-dimensional needling technology, reinforcing the silicon carbide fibers in the plane direction, combining a silicon carbide net tire as interlayer filling, increasing layer by layer, and needling layer by layer to obtain the silicon carbide fiber laminated three-dimensional needling preform. Wherein the density of the preform is 0.6g/cm³The needling density is 30 needles/cm²The interlayer density was 20 layers/10 mm.

Step two: preparation of the powder mixture

Weighing 162g of SiC powder with the average diameter of 30 mu m, 81g of aluminum alloy powder with the average diameter of 20 mu m and 27g of Ni powder with the average diameter of 50 mu m, wherein the mass fractions of the powder are 60%, 30% and 10%; 835g of Al with a diameter of 6mm was weighed₂O₃Grinding balls; taking 333.8g of mixed solution of polyethylene glycol and ethanol, wherein the mass fraction of the polyethylene glycol in the mixed solution is 5%.

(1) Ultrasonically treating the SiC powder in deionized water for 30min, standing for 25min, pouring the deionized water together with the fine SiC particles suspended in the deionized water, and repeatedly elutriating for 3-5 times until the deionized water is completely clear; and (4) keeping the temperature of the washed SiC powder at 120 ℃ and drying for 12h for later use.

(2) The dried SiC powder is roasted for 1h at the high temperature of 850 ℃, and then the temperature is kept for 5h at the temperature of 300 ℃ so that the SiC is pre-oxidized at the high temperature and a layer is formed on the surfaceDense SiO₂Layer, then cooled to room temperature.

(3) Mixing the oxidized 60% SiC powder, 10% Ni powder, 30% Al-Al alloy powder and a dispersing agent, dry-milling in a high-energy ball mill (the rotating speed is 400r/min) for 10 hours, and promoting the raw material powder to be uniformly dispersed by using a grinding ball, wherein the powder comprises the following components in percentage by weight: grinding balls: dispersant 1:3: 1.2; and finally, placing the ball-milled mixed powder into a vacuum drying oven at 45 ℃ for constant-temperature drying for 12 hours.

Ultrasonically cleaning and drying a silicon carbide fiber porous preform, putting the preform subjected to needle punching forming into a graphite sintering mold by adopting a vacuum pressureless infiltration method, paving mixed powder with the thickness of 8mm on the upper surface and the lower surface of the preform, adding 8.1g of chromium powder additive, and immersing and embedding the preform subjected to needle punching forming uniformly by using the chromium powder and the mixed powder in S102 so as to enable the preform to be in uniform contact. Filling nitrogen into a high-temperature vacuum furnace with the absolute vacuum degree of 20Pa for protection, infiltrating at 1200 ℃, keeping the temperature at the rate of 5 ℃/min, keeping the temperature for 2.5h, enabling Al alloy to be molten and infiltrated into the preform, reacting with SiC powder and Ni powder introduced into the preform, cooling to room temperature, and demolding to obtain the silicon carbide fiber reinforced Ni-Al/SiC fiber reinforced Ni-Al/SiC_pA ceramic matrix composite preform sample; proper infiltration and heat preservation time is carried out, which is beneficial to the tight combination between SiC particles and aluminum alloy and prevents Al₄C₃Generation of a harmful interface; then cooling to room temperature and demoulding to obtain the silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform samples. Wherein, the cooling to the room temperature specifically comprises the following steps: cooling at a rate of 5 deg.C/min before 900 deg.C, maintaining at 900 deg.C for 30min, and rapidly cooling to room temperature at 10 deg.C/min. The whole pressureless infiltration process is carried out under the protection of flowing high-purity nitrogen with the volume percentage of 99.99 percent, and the flow rate of the nitrogen is 80 mL/min.

Step four: composite preform sample pre-oxidation

The obtained pre-shaped sample is put into a tube furnace, heated to 660 ℃ and heated to O₂Keeping the temperature for 5 hours in the atmosphere to thoroughly eliminate the residual Al alloy powder pair compositionInfluence of high temperature properties of the material; then grinding, washing, drying and drying at 80 ℃ for 2h to obtain the preoxidized silicon carbide fiber reinforced Ni-Al/SiC_pCeramic matrix composite preform samples.

It should be noted that, in addition to the cases listed in the above examples one and two, other preparation process parameters may be selected.

The Ni-Al/SiC provided by the invention_pThe ceramic matrix composite has excellent high-temperature oxidation resistance and corrosion resistance, and effectively overcomes the defects of the traditional SiC_fThe problem of matrix oxidation corrosion in the SiC ceramic matrix composite engine environment; finally prepared continuous silicon carbide fiber reinforced Ni-Al/SiC with low oxygen content_pThe density of the ceramic matrix composite material is more than 97%, the oxygen content is 3-5 wt%, and SiC in the composite material is added_pThe content is increased, the bending strength is increased from 450MPa to 485MPa, and the thermal expansion coefficient is increased from 9.8 × 10^-6The K is reduced to 8.2 × 10^-6K, fracture toughness in SiC_pThe content of the additive can reach 18 MPa.m when 65 percent^1/2。

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. The preparation method of the ceramic matrix composite is characterized by comprising the following steps:

s101: selecting silicon carbide fibers with high strength, high hardness, good toughness and low oxygen content, carrying out needling forming by using a three-dimensional needling technology, reinforcing the silicon carbide fibers in the plane direction, combining a silicon carbide net tire as interlayer filling, increasing layer by layer, and needling layer by layer to obtain a silicon carbide fiber laminated three-dimensional needling preform;

s102: elutriating SiC powder by using deionized water until the deionized water is completely clear, and drying the elutriated SiC powder; carrying out high-temperature pre-oxidation on the dried SiC powder to form compact SiO on the surface₂Layer, then cooling to room temperature; uniformly mixing Ni powder, aluminum alloy powder, a dispersing agent and the oxidized SiC powder, and then carrying out vacuum drying to obtain mixed powder;

s103: ultrasonically cleaning and drying the silicon carbide fiber laminated three-dimensional needling preform, putting the needling-formed preform into a graphite sintering mold by adopting a vacuum pressureless infiltration method, and paving the mixed powder with a preset thickness on the upper surface and the lower surface of the preform; then adding Cr powder additive, carrying out high-temperature vacuum infiltration, cooling the product subjected to high-temperature vacuum infiltration to room temperature, and demolding to obtain the silicon carbide fiber reinforced Ni-Al/SiC_pA ceramic matrix composite preform sample;

s104: pre-oxidizing the preformed sample obtained in the step S103, polishing, washing and drying to obtain pre-oxidized silicon carbide fiber reinforced Ni-Al/SiC_pA ceramic matrix composite preform sample;

s105: putting the preformed sample obtained in the step S104 into a graphite sintering mold again, repeating the operations of the step S103 and the step S104 until the weight gain of the preformed samples in two adjacent steps is less than 1%, and finally obtaining the compact continuous silicon carbide fiber reinforced Ni-Al/SiC_pA ceramic matrix composite;

in the step S102:

uniformly mixing Ni powder, aluminum alloy powder, a dispersing agent and the oxidized SiC powder in a high-energy ball mill; wherein the mass ratio of the SiC powder, the Ni powder and the aluminum alloy powder is (50-70): (10-15): (30-50), the ball milling rotating speed is 300-450 r/min, and the time is 8-10 h; the particle size of the aluminum alloy powder is 10-20 mu m, the content of Si in the aluminum alloy is 7-15%, the content of Mg in the aluminum alloy is 6-10%, and the balance is Al; the particle size of the Ni powder is 40-50 mu m, and the purity is more than 99.9%.

2. The method of preparing a ceramic matrix composite according to claim 1, wherein:

in the step S101:

the density of the silicon carbide fiber laminated three-dimensional needling preform is 0.2-0.6 g/cm³The needling density is 5 to 45 needles/cm²The interlayer density is 1-20 layers/10 mm;

the silicon carbide fiber with high strength, high hardness, good toughness and low oxygen content is specifically as follows: the content of Si is 56-60 wt%, the content of C is 30-40 wt%, the content of O is 3-5 wt%, the average diameter is 10-15 μm, the tensile strength is 2-3 GPa, and the Young modulus is 200-240 GPa.

3. The method of preparing a ceramic matrix composite according to claim 1, wherein:

in the step S102:

the elutriating of the SiC powder by using the deionized water specifically comprises the following steps: ultrasonically treating the SiC powder in deionized water for 15-30 min, standing for 10-25 min, filtering, collecting a solid phase, and repeatedly elutriating for 3-5 times; in the washed SiC powder, the average grain diameter of the SiC powder is 14-30 mu m, and the purity is more than 99.9%; and drying the washed SiC powder for 10-15 h at the temperature of 110-120 ℃.

4. The method of preparing a ceramic matrix composite according to claim 1, wherein:

in the step S102:

the high-temperature pre-oxidation specifically comprises the following steps: roasting the dried SiC powder at the high temperature of 800-850 ℃ for 0.5-1.5 h, and then preserving heat at the temperature of 280-310 ℃ for 3-5 h;

the temperature of the vacuum drying is 40-50 ℃, and the time is 10-15 h.

5. The method of preparing a ceramic matrix composite according to claim 1, wherein:

in the ball milling process, the milling ball is Al₂O₃The diameter of the hard alloy is 6-15 mm; wherein, the powder lot: grinding balls: the dispersant is 1 (3-6) and 0.8-1.2, the dispersant is a mixed solution of polyethylene glycol and ethanol, and the mass fraction of the polyethylene glycol in the mixed solution of the polyethylene glycol and the ethanol is 3-5%.

6. The method of preparing a ceramic matrix composite according to claim 1, wherein:

in the S104:

the pre-oxidation treatment is carried out in a tube furnace, and the specific conditions comprise: putting the preformed sample into a tube furnace, heating to 660-700 ℃, and heating to O₂Preserving heat for 3-5 h under the atmosphere; and the drying temperature is 80-120 ℃, and the drying time is 1-2 h.

7. Continuous silicon carbide fiber reinforced Ni-Al/SiC prepared by the method of any one of claims 1 to 6_pA ceramic matrix composite.