CN111018537A

CN111018537A - Method for preparing carbon fiber reinforced SiC ceramic matrix composite material through 3D printing

Info

Publication number: CN111018537A
Application number: CN201911309391.4A
Authority: CN
Inventors: 李晨辉; 邹阳; 史玉升; 胡梁; 刘江安; 吴甲民
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2019-12-18
Filing date: 2019-12-18
Publication date: 2020-04-17
Also published as: WO2021120636A1

Abstract

The invention belongs to the field of composite materials, and particularly discloses a method for preparing a carbon fiber reinforced SiC ceramic matrix composite material by 3D printing, which comprises the following steps: mixing SiC powder with chopped carbon fibers and a binder to obtain mixed powder; carrying out selective laser sintering forming on the mixed powder to obtain a SiC/chopped carbon fiber green body; carrying out carbonization treatment after the surface of the SiC/chopped carbon fiber green blank is cleaned, then impregnating the SiC/chopped carbon fiber green blank with an organic carbon precursor solution, drying the solution and carrying out secondary carbonization treatment to obtain a SiC/chopped carbon fiber/carbon green blank; and performing densification treatment on the SiC ceramic matrix composite material by adopting a liquid phase siliconizing method to obtain the carbon fiber reinforced SiC ceramic matrix composite material. The secondary carbonization of the invention not only can increase the strength of the blank body by means of the residual phase of the carbon precursor after curing and pyrolysis, and is convenient for subsequent operation, but also is beneficial to the exertion of the toughening effect of the chopped carbon fiber; in addition, the space net-shaped secondary carbon formed after carbonization and cracking can further enhance the mechanical property of the composite material.

Description

Method for preparing carbon fiber reinforced SiC ceramic matrix composite material through 3D printing

Technical Field

The invention belongs to the field of composite materials, and particularly relates to a method for preparing a carbon fiber reinforced SiC ceramic matrix composite material through 3D printing.

Background

With the rapid development of the technological level in the fields of aerospace, automobiles, space optics and the like, the requirements of core components, such as a hypersonic aircraft thermal protection system, an aircraft engine hot end component, a high-performance brake system, a space reflector and the like, on the material performance are more and more strict. The SiC ceramic matrix composite is expected to be successfully applied in the fields due to the excellent performances of low density, high thermal conductivity, ablation erosion resistance, wear resistance and the like. However, the SiC ceramic has high brittleness and crack sensitivity, and the inherent difficult processing characteristic restricts the material from being formed into a complex structural part, thereby greatly limiting the application range. For SiC ceramic materials with complex structures, the traditional processing means has the problems of complex process and high manufacturing cost. If a biscuit is obtained by mould pressing or cold isostatic pressing, the forming process of machining the biscuit into a required shape by means of numerical control machine (CNC) equipment depends heavily on the machining capability of the CNC, and the machining cost is high for some components with complex topological optimization structures (such as honeycomb structures with sandwich layers), and sometimes even the design requirements are difficult to achieve. The ceramic wet forming technologies such as slip casting, gel casting and direct solidification which are frequently used in recent years can be used for preparing complex structures, but the methods all need moulds, are high in cost for small-batch production and are not suitable for personalized customization. In addition, the ceramic wet forming technology needs to prepare slurry with high solid content and good fluidity, and the solid content of the actual slurry hardly exceeds 70 wt%, so that the blank is difficult to avoid certain shrinkage in the later solidification, degreasing and sintering stages, and the geometric precision of the sample is relatively low.

The additive manufacturing is listed as an advanced manufacturing technology which improves national competitiveness and needs to be developed urgently in response to future challenges, wherein the emergence of a Selective Laser Sintering (SLS) technology brings new possibility for quickly and efficiently forming large-scale complex ceramic parts. As one of 3D printing (additive manufacturing) technologies, the SLS technology is suitable for quickly manufacturing parts with complex structures and special shapes and can meet the requirements of quickly forming and manufacturing various ceramic parts such as whole parts, split parts and the like; and a support structure is not required to be arranged in the SLS technology forming process, so that the post-treatment process of the formed part is simplified, and the problem of preparation of the SiC ceramic matrix composite part with the complex structure is expected to be solved. In recent years, research on rapid prototyping of ceramic materials by selective laser sintering has been reported, for example, CN200510020015.5 discloses a method for preparing rapid prototyping SiC ceramics by laser sintering, which comprises prototyping a SiC preform by laser sintering, then infiltrating silicon metal and treating with alkali solution to obtain SiC ceramics with complex shape, but the SiC powder used in the method needs to be granulated by spraying to ensure good fluidity, so that the method requires high cost of raw materials and complicated preparation process.

One major drawback to SiC ceramic matrix composites is the poor toughness of the material, which limits the reliability of parts made from such materials. The carbon fiber is an important one-dimensional reinforced material, and has been used for improving the mechanical property of the traditional ceramic matrix composite material with great success. However, due to the adverse effect of the fiber on the powder laying performance of the powder, the fiber is less applied to selective laser sintering forming based on a powder bed at present. The document "Fabrication and characterization of carbon fiber reinforced SiC Ceramic composites based on 3D printing technology" (Journal of the Eueopean carbon Society 38, 4604. the 4613) discloses a method for preparing a chopped carbon fiber reinforced SiC composite material based on a selective laser sintering and liquid phase siliconizing method, wherein PF/chopped carbon fiber-Si (phenolic resin coated carbon fiber-Si composite powder) used in the method is prepared by a solvent evaporation method, and the problems of high raw material cost and complicated preparation process are also faced, and the problems of poor geometric precision and large size shrinkage in the carbonization process of the formed green body are difficult to avoid due to the low loose density and poor fluidity of the powder because the green body is formed by using the chopped carbon fiber and a small amount of Si powder.

Disclosure of Invention

Aiming at the defects and/or improvement requirements in the prior art, the invention provides a method for preparing a carbon fiber reinforced SiC ceramic matrix composite material by 3D printing, wherein the method comprises the steps of impregnating a carbonized green body with an organic carbon precursor solution and carrying out secondary carbonization treatment, so that the strength of the green body can be increased by virtue of a residual phase obtained after the carbon precursor is cured and pyrolyzed, the subsequent operation is facilitated, the reinforcing and toughening effects of chopped carbon fibers are effectively improved, and in addition, the pores in the green body can be refined by utilizing space-network secondary carbon formed after carbonization and pyrolysis, so that the carbon fiber reinforced SiC ceramic matrix composite material with excellent rupture strength and fracture toughness is prepared, and therefore, the method is particularly suitable for manufacturing parts such as a hypersonic aircraft thermal protection system, an aircraft engine hot end part, a high-performance brake system, a space telescope blank and the.

To achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a carbon fiber reinforced SiC ceramic matrix composite by 3D printing, the method comprising the steps of:

(a) mixing SiC powder with chopped carbon fibers and a binder to obtain mixed powder;

(b) carrying out selective laser sintering forming on the mixed powder to obtain a SiC/chopped carbon fiber green body;

(c) carrying out carbonization treatment after the surface of the SiC/chopped carbon fiber green blank is cleaned, then impregnating the SiC/chopped carbon fiber green blank with an organic carbon precursor solution, drying the solution and carrying out secondary carbonization treatment to obtain a SiC/chopped carbon fiber/carbon green blank;

(d) and performing densification treatment on the SiC/chopped carbon fiber/carbon blank by adopting a liquid phase siliconizing method to finally obtain the carbon fiber reinforced SiC ceramic matrix composite.

More preferably, in the step (a), the particle size distribution in the SiC powder is specifically: the powder with the particle size of 0.1-2 mu m accounts for 0-5 wt% of the whole SiC powder, the powder with the particle size of 2-40 mu m accounts for 22-55 wt% of the whole SiC powder, and the powder with the particle size of 40-250 mu m accounts for 42-75 wt% of the whole SiC powder.

More preferably, in the step (a), the diameter of the chopped carbon fiber is 0.1-20 μm, the length-diameter ratio thereof is 5-500, and the addition amount of the chopped carbon fiber accounts for 1-20 wt% of the total SiC powder.

Further preferably, in the step (a), the binder is one or more of epoxy resin, phenolic resin or nylon 12, and the addition amount of the binder is 3-20 wt% of the SiC powder.

More preferably, in the step (b), the specific method for performing selective laser sintering forming is as follows: and paving powder by adopting a manual or mechanical method, and then irradiating a specific region of the powder bed layer by using laser to obtain the SiC/chopped carbon fiber green body based on slice data obtained by a three-dimensional model of the target forming body.

As a further preference, in step (c), the organic carbon precursor solution is one or more of an epoxy resin solution, a phenolic resin solution or a pitch solution.

As a further preferred, in the step (c), the specific process of the carbonization treatment or the secondary carbonization treatment is: and placing the sample to be carbonized in a non-oxidizing atmosphere, slowly heating the sample within the pyrolysis temperature range of the binder or the carbon precursor, then quickly heating the sample to the target temperature of 850-1100 ℃, and preserving the temperature for 1.0-6 h to carbonize the sample.

As a further preferred, in the step (d), the specific process of the liquid phase siliconizing method is: embedding the SiC/chopped carbon fiber/carbon blank in metal Si, heating to a target temperature of 1420-1800 ℃ under a vacuum condition, and preserving heat for 0.25-3 h.

According to another aspect of the invention, a carbon fiber reinforced SiC ceramic matrix composite prepared by the method is provided.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. according to the invention, the carbonized green body is impregnated by using an organic carbon precursor solution, and then is heated to carry out secondary carbonization treatment, so that the residual phase of the carbonized green body after the carbon precursor is cured and pyrolyzed can be utilized, the strength of the green body is increased, the subsequent operation is convenient, and secondary carbon generated by cracking the green body can be attached to the surface of a matrix material in a pore to be used as a carbon consumption layer to reduce the damage of molten Si to matrix chopped carbon fibers, thereby being beneficial to the exertion of the toughening effect of the chopped carbon fibers; in addition, the space net-shaped secondary carbon formed after the carbonization and cracking of the carbon precursor can further refine and divide micron-sized pores in the precursor into a plurality of nano-sized pores, so that the effect of separating large-size residual Si in the composite material into submicron or nano-sized Si particles is realized, and the mechanical property of the composite material can be further enhanced;

2. particularly, the SiC powder is optimized in particle size distribution, so that the stacking behavior of the mixed powder can be effectively optimized, the adverse effect of adding the chopped carbon fibers on the fluidity of the mixed powder is compensated, the mixed powder has better fluidity and larger apparent density, the mixed powder can be ensured to have good fluidity and SLS forming performance only by adopting simple mechanical mixing, and the complicated processes such as a dissolving precipitation method or a solvent evaporation method required by the preparation of raw material powder in the current ceramic SLS rapid forming process are omitted, so that the preparation cost is greatly reduced;

3. in addition, the process and the process parameters for preparing the carbon fiber reinforced SiC ceramic matrix composite material by 3D printing are optimized, so that the carbon fiber reinforced SiC ceramic matrix composite material with the relative density of more than 98 percent, the breaking strength of more than 180MPa and the fracture toughness of more than 2.5 MPa.m can be obtained under the combined action of the process parameters^0.5The carbon fiber reinforced SiC ceramic matrix composite material.

Drawings

FIG. 1 is a process flow chart for preparing a carbon fiber reinforced SiC ceramic matrix composite by 3D printing provided by the invention;

FIG. 2 is a schematic view of the phase composition distribution of the carbon fiber reinforced SiC ceramic matrix composite prepared according to the preferred embodiment of the present invention;

FIG. 3 is a microstructure photograph of a SiC/chopped carbon fiber green body containing 6 wt% chopped carbon fibers made in example 6 of the present invention;

FIG. 4 is a microstructure photograph of a corroded section of a carbon fiber reinforced SiC ceramic matrix composite containing 6 wt% of chopped carbon fibers prepared in example 6 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1, the invention provides a method for preparing a carbon fiber reinforced SiC ceramic matrix composite by 3D printing, which comprises the following steps:

(d) and (3) performing densification treatment on the SiC/chopped carbon fiber/carbon blank by adopting a liquid phase siliconizing method to finally obtain the carbon fiber reinforced SiC ceramic matrix composite.

Further, in the step (a), the particle size distribution of the SiC powder can be finely designed through a particle stacking density model (such as a multi-element powder particle stacking density model corrected based on the stopval linear stacking theory), so as to optimize the stacking behavior of the mixed powder, and the specific situation of the particle size distribution in the SiC powder is determined through calculation as follows: the powder with the particle size of 0.1-2 mu m accounts for 0-5 wt% of the whole SiC powder, the powder with the particle size of 2-40 mu m accounts for 22-55 wt% of the whole SiC powder, and the powder with the particle size of 40-250 mu m accounts for 42-75 wt% of the whole SiC powder; in order to ensure that the mixed powder has good flowability and a large bulk density, the particle size distribution in the SiC powder may be further preferably: the powder with the particle size of 0.1-2 mu m accounts for 0.6-1.8 wt% of the whole SiC powder, the powder with the particle size of 2-40 mu m accounts for 35-44 wt% of the whole SiC powder, the powder with the particle size of 40-250 mu m accounts for 55-64 wt% of the whole SiC powder, and the maximum particle size is not more than 150 mu m.

Further, in the step (a), the diameter of the short carbon fiber is 0.1-20 μm, the length-diameter ratio of the short carbon fiber is 5-500, the addition amount of the short carbon fiber accounts for 1-20 wt% of the total SiC powder, the binder is one or more of epoxy resin, phenolic resin or nylon 12, the addition amount of the binder is 3-20 wt% of the SiC powder, and the horizontal mixing equipment, the vertical mixing equipment or the three-dimensional mixing equipment is adopted for mechanical mixing; in order to improve the geometric accuracy and mechanical property of the SiC/chopped carbon fiber green body as much as possible, the chopped carbon fiber with the diameter of 5-10 mu m and the length-diameter ratio of 100-200 is preferably selected, and the addition amount of the chopped carbon fiber is preferably 4-8 wt% of the total SiC powder; the binder is preferably epoxy resin or nylon 12, and the addition amount of the binder is preferably 6-10 wt% of the mass of the SiC powder.

Further, in the step (b), the specific method for carrying out selective laser sintering forming comprises the following steps: firstly, paving powder by adopting a manual or mechanical method, then obtaining slice data based on a three-dimensional model of a target forming body, and utilizing laser to irradiate a specific region of a powder bed layer by layer according to the slice data to obtain a SiC/chopped carbon fiber green body, wherein in order to obtain the SiC/chopped carbon fiber green body with higher forming precision, the type of the used laser is preferably continuous wavelength CO₂And (4) laser.

Further, in step (c), the organic impregnant is one or more of an epoxy resin solution, a phenolic resin solution or an asphalt solution, preferably a phenolic resin solution or an asphalt solution.

Further, in the step (c), the carbonization treatment or the secondary carbonization treatment comprises the following specific processes: placing a sample to be carbonized in a non-oxidizing atmosphere, carrying out heat treatment in a high-temperature furnace, setting a temperature rise system to slowly rise within the pyrolysis temperature range of a binder or a carbon precursor, then quickly rising to the target temperature of 850-1100 ℃, and preserving heat for 1.0-6 h to carry out carbonization;

in order to ensure that the sample does not have cracking deformation and is fully carbonized, the temperature rise rate below 650 ℃ is preferably not more than 1.5 ℃/min, the target temperature is preferably 950-1000 ℃, and the holding time is preferably 2-3 h.

Further, in the step (d), the liquid phase siliconizing method comprises the following specific processes: embedding SiC/chopped carbon fiber/carbon blank in metal Si, placing the metal Si and the SiC/chopped carbon fiber/carbon blank together in a high-temperature sintering furnace, starting a vacuumizing device to remove air in the furnace, simultaneously heating the sample and the metal Si to a target temperature of 1420-1800 ℃ and preserving heat for 0.25-3 h; in order to facilitate the sufficient penetration of liquid silicon and avoid excessive sintering of the sample, the target temperature is preferably 1550-1650 ℃, and the heat preservation time is preferably 0.5-1.0 h.

The phase composition distribution of the carbon fiber reinforced SiC ceramic matrix composite material obtained by the preparation method is shown in figure 2, if the detected relative density is more than 98 percent, the breaking strength is more than 180MPa, and the fracture toughness is more than 2.5 MPa.m^0.5。

The invention is further illustrated by the following examples.

Example 1

(a) Preparing SiC powder with a preset particle size distribution range according to the blending ratio obtained by model calculation, wherein the SiC powder with the particle size of 0.1-2 microns accounts for 0 wt%, the SiC powder with the particle size of 2-40 microns accounts for 55 wt%, and the SiC powder with the particle size of 40-250 microns accounts for 45 wt%, then blending the chopped carbon fibers and the nylon 12 with the diameter of 0.1-20 microns and the length-diameter ratio of 5-500 with the SiC powder with the preset particle size distribution range according to the mass ratio of 1:20:100, placing the mixture in a roller mixer, adding grinding balls according to the ball-to-material ratio of 1:1, and mechanically mixing for 2 hours to obtain SiC-chopped carbon fiber-nylon 12 mixed powder;

(b) sintering and forming the mixed powder in a selective laser region to obtain SiC/short powderCutting carbon fiber green body, wherein the laser used in the process is CO with the wavelength range of 9.8-10.2 mu m₂Laser, wherein the diameter of a light spot of the laser is 0.15mm, the power of the laser is 6W, the powder spreading thickness of the powder is 0.15mm, the preheating temperature is 145 ℃, and the scanning rate is 1300mm/s, wherein the laser power at the outline position of the model is 0.5 times of that in the model, and the scanning rate at the outline position of the model is 2 times of that in the model, so that the SiC/chopped carbon fiber green compact with the target shape is obtained;

(c) the surface of the SiC blank is cleaned and then placed in a tube furnace, and is vacuumized and N-filled for 2 times₂Maintaining N in the furnace after operation₂The pressure is not less than 1 atmosphere, then a tube furnace is heated, the temperature is increased from normal temperature to 200 ℃ at the heating rate of 1.05 ℃/min, then the temperature is increased to 480 ℃ at the heating rate of 1 ℃/min, the temperature is kept for 2h at the temperature, then the temperature is continuously increased to 650 ℃ at the heating rate of 1.25 ℃/min, the temperature is kept for 0.5h at the temperature, finally the temperature is increased to 850 ℃ at the heating rate of 6.5 ℃/min, and the temperature is kept for 6h, so that a carbonized blank body is obtained; immersing the carbonized green body in a thermosetting phenolic resin solution, vacuumizing until the absolute pressure is less than 0.003MPa, continuously vacuumizing for 30min under the pressure, putting the green body which is impregnated with the phenolic resin, dried and cured in a tubular furnace, heating the tubular furnace to 750 ℃ at the heating rate of not more than 1 ℃/min under the Ar gas condition, continuously heating to 1000 ℃, and preserving heat for 3h for secondary carbonization;

(d) burying the blanks subjected to secondary carbonization in a certain amount of metal Si, and placing the blanks in a high-temperature sintering furnace together; and starting a vacuumizing device to remove air in the furnace, and simultaneously heating the sample and the metal Si to 1420 ℃ and preserving the heat for 3 hours to obtain the carbon fiber reinforced SiC ceramic matrix composite.

The SiC-chopped carbon fiber-nylon 12 mixed powder has good fluidity in the preparation process, the prepared SiC/chopped carbon fiber green compact has high geometric precision, the size shrinkage rate is small in the carbonization process, and the prepared carbon fiber reinforced SiC ceramic matrix composite has high breaking strength and fracture toughness.

Example 2

(a) Preparing SiC powder with a preset particle size distribution range according to the blending ratio obtained by model calculation, wherein the SiC powder with the particle size of 0.1-2 microns accounts for 5 wt%, the SiC powder with the particle size of 2-40 microns accounts for 53 wt%, and the SiC powder with the particle size of 40-250 microns accounts for 42 wt%, then blending the chopped carbon fibers with the diameter of 0.1-20 microns and the length-diameter ratio of 5-500, phenolic resin (PF) and the SiC powder with the preset particle size distribution range according to the mass ratio of 20:3:100 in a roller mixer, adding grinding balls according to the ball-to-material ratio of 2:1, and then mechanically mixing for 2 hours to obtain SiC-chopped carbon fiber-PF mixed powder;

(b) carrying out selective laser sintering and forming on the mixed powder to obtain a SiC/chopped carbon fiber green body, wherein the conditions except the preheating temperature of 125 ℃ in the selective laser sintering and forming process are the same as those in the embodiment 1;

(c) cleaning the surface of the SiC blank, placing the SiC blank in a tube furnace, maintaining the Ar gas atmosphere in the furnace, heating the tube furnace, heating the rough blank from the normal temperature to 700 ℃ at the heating rate of not more than 1.0 ℃/min, preserving heat at the temperature for 1.0h, heating the rough blank to 1100 ℃ at the speed of 6 ℃/min, and preserving heat for 1.0h to obtain a carbonized blank; immersing the carbonized green body in an asphalt solution, then placing the green body in a vacuum drying oven at 80 ℃ for vacuumizing until the absolute pressure is less than 0.005MPa, and continuously vacuumizing for 30min under the pressure to ensure that the asphalt solution fully permeates into the sample; placing the green blank which is impregnated with the asphalt solution and dried and cured in a tubular furnace, heating to 850 ℃ at a speed of not more than 1.0 ℃/min under the Ar atmosphere condition, preserving heat for 0.5h, continuously heating to 1100 ℃, preserving heat for 2.0h, and carrying out secondary carbonization;

(d) burying the blanks subjected to secondary carbonization in a certain amount of metal Si, and placing the blanks in a high-temperature sintering furnace together; starting a vacuumizing device to remove air in the furnace, simultaneously heating the sample and the metal Si to 1800 ℃ and preserving the temperature for 0.25h to obtain the carbon fiber reinforced SiC ceramic matrix composite.

Example 3

(a) Preparing SiC powder with a preset particle size distribution range according to the blending ratio obtained by model calculation, wherein the SiC powder with the particle size of 0.1-2 microns accounts for 3 wt%, the SiC powder with the particle size of 2-40 microns accounts for 22 wt%, and the SiC powder with the particle size of 40-250 microns accounts for 75 wt%, then blending the chopped carbon fibers and the nylon 12 with the diameter of 0.1-20 microns and the length-diameter ratio of 5-500 with the SiC powder with the preset particle size distribution range according to the mass ratio of 10:12:100, placing the mixture in a roller mixer, adding grinding balls according to the ball-to-material ratio of 1:1, and then mechanically mixing for 1.0h to obtain SiC-chopped carbon fiber-nylon 12 mixed powder;

(b) carrying out selective laser sintering and forming on the mixed powder to obtain a SiC/chopped carbon fiber green body, wherein the experimental conditions of selective laser sintering and forming are the same as those of the embodiment 1;

(c) the surface of the SiC blank is cleaned and then placed in a tube furnace, and is vacuumized and N-filled for 3 times₂Maintaining N in the furnace after operation₂The pressure is not less than 1 atmosphere, then a tube furnace is heated, the temperature is increased from normal temperature to 200 ℃ at the heating rate of 1.05 ℃/min, then the temperature is increased to 480 ℃ at the heating rate of 1 ℃/min, the temperature is kept for 2h, then the temperature is continuously increased to 650 ℃ at the heating rate of 1.25 ℃/min, the temperature is kept for 0.5h, finally the temperature is increased to 1000 ℃ at the heating rate of 6.5 ℃/min, and the temperature is kept for 2h, so that a carbonized blank body is obtained; immersing the carbonized blank body in an epoxy resin solution mixed with 8 wt% of triethanolamine, quickly vacuumizing at 80 ℃ until the absolute pressure is less than 0.005MPa, maintaining the pressure for 15min, putting the green blank impregnated with the phenolic resin, dried and cured in a tube furnace, and putting the green blank in a N-shaped furnace₂Heating the tube furnace to 750 ℃ at a heating rate of not more than 1 ℃/min under the atmosphere condition, then continuously heating to 850 ℃, and preserving heat for 6 hours for secondary carbonization;

(d) burying the blanks subjected to secondary carbonization in a certain amount of metal Si, and placing the blanks in a high-temperature sintering furnace together; and starting a vacuumizing device to remove air in the furnace, and simultaneously heating the sample and the metal Si to 1550 ℃ and preserving the temperature for 1.0h to obtain the carbon fiber reinforced SiC ceramic matrix composite.

Example 4

(a) Preparing SiC powder with a preset particle size distribution range according to the blending ratio obtained by model calculation, wherein the SiC powder with the particle size of 0.1-2 microns accounts for 0.6 wt%, the SiC powder with the particle size of 2-40 microns accounts for 44 wt%, and the SiC powder with the particle size of 30-150 microns accounts for 55.4 wt%, then blending the chopped carbon fibers and the epoxy resin with the diameter of 5-10 microns and the length-diameter ratio of 100-200 with the SiC powder with the preset particle size distribution range according to the mass ratio of 4:6:100, placing the mixture in a roller mixer, adding grinding balls according to the ball-to-material ratio of 4:1, and then mechanically mixing for 4 hours to obtain SiC-chopped carbon fiber-epoxy resin mixed powder;

(b) the mixed powder is used for selective laser sintering and forming, and the laser used in the selective laser sintering and forming process is CO with the wavelength of 9.8-10.2 mu m₂Laser, wherein the diameter of a light spot of the laser is 0.15mm, the power of the laser is 6W, the powder spreading thickness of the powder is 0.15mm, the preheating temperature is 45 ℃, and the scanning rate is 1300mm/s, wherein the laser power at the outline position of the model is 0.5 times of that in the model, and the scanning rate at the outline position of the model is 2 times of that in the model, so that a SiC/chopped carbon fiber green body is obtained;

(c) cleaning the surface of the SiC blank, placing the SiC blank in a tube furnace, maintaining the reducing atmosphere in the furnace, then heating the tube furnace, heating the rough blank from the normal temperature to 700 ℃ at the heating rate of 1.5 ℃/min, preserving the heat at the temperature for 1.0h, heating the rough blank to 950 ℃ at the rate of 6 ℃/min, and preserving the heat for 3h to obtain a carbonized blank; immersing the carbonized green body in a phenolic resin solution added with 10 wt% of dilute hydrochloric acid, quickly vacuumizing until the absolute pressure is less than 1000Pa, continuously vacuumizing for 30min under the pressure to infiltrate the phenolic resin, putting the sample which is infiltrated with the phenolic resin and dried and cured in a tube furnace to carry out secondary carbonization, wherein the secondary carbonization process is the same as the secondary carbonization process used in the embodiment 1.

(d) Burying the blanks subjected to secondary carbonization in a certain amount of metal Si, and placing the blanks in a high-temperature sintering furnace together; starting a vacuumizing device to remove air in the furnace, simultaneously heating the sample and the metal Si to 1650 ℃, and preserving the temperature for 0.5h to obtain the carbon fiber reinforced SiC ceramic matrix composite.

The carbon fiber reinforced SiC ceramic matrix composite material obtained according to the embodiment is detected to have the volume density of 2.70 g-cm^-3The apparent porosity is 0.27%, the bending strength reaches 202MPa, and the fracture toughness is about 3.0 MPa.m^0.5。

Example 5

(a) Preparing SiC powder with a preset particle size distribution range according to the blending ratio obtained by model calculation, wherein the SiC powder with the particle size of 0.1-2 microns accounts for 1.8 wt%, the SiC powder with the particle size of 2-40 microns accounts for 43.2 wt%, and the SiC powder with the particle size of 30-150 microns accounts for 55 wt%, then blending the chopped carbon fibers and the epoxy resin with the diameter of 5-10 microns and the length-diameter ratio of 100-200 with the SiC powder with the preset particle size distribution range according to the mass ratio of 8:10:100, placing the mixture in a roller mixer, adding grinding balls according to the ball-to-material ratio of 4:1, and then mechanically mixing for 4 hours to obtain SiC-chopped carbon fiber-epoxy resin mixed powder;

(b) carrying out selective laser sintering forming by using the mixed powder, wherein the process conditions and parameters adopted in the process are the same as those of the embodiment 4;

(c) cleaning the surface of the SiC blank, placing the SiC blank in a tube furnace, maintaining the reducing atmosphere in the furnace, then heating the tube furnace, heating the rough blank from the normal temperature to 700 ℃ at the heating rate of 1.5 ℃/min, preserving the heat at the temperature for 1.0h, heating the rough blank to 1000 ℃ at the speed of 6 ℃/min, and preserving the heat for 2h to obtain a carbonized blank; immersing the carbonized green body in a phenolic resin solution added with 12 wt% of dilute hydrochloric acid, quickly vacuumizing until the absolute pressure is less than 1000Pa, continuously vacuumizing for 30min under the pressure to infiltrate the phenolic resin, putting a sample which is impregnated with the phenolic resin, dried and cured in a tube furnace, and putting the sample in a N-shaped furnace₂Heating to 850 ℃ at a speed of not more than 1.2 ℃/min under the condition, then preserving heat for 1.0h, continuously heating to 950 ℃, preserving heat for 3h, and carrying out secondary carbonization;

(d) burying the blanks subjected to secondary carbonization in a certain amount of metal Si, and placing the blanks in a high-temperature sintering furnace together; and starting a vacuumizing device to remove air in the furnace, and simultaneously heating the sample and the metal Si to 1550 ℃ and preserving the temperature for 1h to obtain the carbon fiber reinforced SiC ceramic matrix composite.

The carbon fiber reinforced SiC ceramic matrix composite material obtained according to the embodiment is detected to have the volume density of 2.64 g-cm^-3The apparent porosity is 0.36%, the bending strength reaches 208MPa, and the fracture toughness is about 3.2 MPa.m^0.5。

Example 6

(a) Preparing SiC powder with a preset particle size distribution range according to the blending ratio obtained by model calculation, wherein the SiC powder with the particle size of 0.1-2 microns accounts for 1 wt%, the SiC powder with the particle size of 2-40 microns accounts for 35 wt%, and the SiC powder with the particle size of 30-150 microns accounts for 64 wt%, then blending the chopped carbon fibers and the phenolic resin with the diameter of 5-10 microns and the length-diameter ratio of 100-200 with the SiC powder with the preset particle size distribution range according to the mass ratio of 6:8:100, placing the blended powder into a roller mixer, adding grinding balls according to the ball-material ratio of 4:1, and then mechanically mixing for 4 hours to obtain SiC-chopped carbon fiber-phenolic resin mixed powder;

(b) the mixed powder is used for carrying out selective laser sintering and forming, and the process adopts the same process conditions and parameters as those of the embodiment 4 except that the preheating temperature is 125 ℃;

(c) cleaning the surface of the SiC blank, placing the SiC blank in a tube furnace, maintaining the reducing atmosphere in the furnace, then heating the tube furnace, heating the rough blank from the normal temperature to 700 ℃ at the heating rate of 1.5 ℃/min, preserving the heat at the temperature for 1.0h, heating the rough blank to 950 ℃ at the rate of 6 ℃/min, and preserving the heat for 3h to obtain a carbonized blank; immersing the carbonized green body in asphalt, quickly vacuumizing until the absolute pressure is less than 1000Pa, continuously vacuumizing for 30min under the pressure to enable the asphalt to fully permeate into pores of a sample, putting the sample which is impregnated with the asphalt, dried and cured in a tubular furnace, heating to 850 ℃ at a temperature not more than 1.2 ℃/min under the condition of carbon burying, preserving heat for 1.0h, and continuously heating to 1100 ℃ and preserving heat for 1.0h to carry out secondary carbonization;

(d) the blanks after the secondary carbonization are buried in a certain amount of metal Si and are placed in a high-temperature sintering furnace together for reaction infiltration, and the process and parameters used in the process are the same as those in the embodiment 4.

The carbon fiber reinforced SiC ceramic matrix composite material obtained according to the embodiment is detected to have the volume density of 2.64 g-cm^-3The apparent porosity is 0.56%, the bending strength reaches 190MPa, and the fracture toughness is about 2.8 MPa.m^0.5。

Fig. 3 is a microstructure photograph of the SiC/chopped carbon fiber green compact obtained in example 6, and it can be seen from the drawing that the distribution shape of the carbon fibers in the SLS-shaped preform is complete and the distribution is relatively uniform, which shows that the particle size distribution of the powder and the mixing manner thereof provided by the present invention can realize uniform dispersion of the carbon fibers in the material.

Fig. 4 is a microstructure photograph of a corrosion section of the carbon fiber reinforced SiC ceramic matrix composite obtained in example 6, and it can be seen that after the molten silicon infiltrates the preform, the siliconized carbon fibers generated by the reaction between the internal carbon fibers and the molten silicon still maintain a high aspect ratio, and because the components of the siliconized carbon fibers are close to SiC in the material matrix and have good interface bonding with each other, the corrosion section can perform the functions of inhibiting crack propagation, such as crack deflection, bridging, fiber extraction and the like, in the material, and is beneficial to the improvement of the mechanical properties of the composite.

Because the particle size distribution of the SiC powder is further optimized in the embodiments 4-6, the obtained mixed powder has better fluidity and larger apparent density compared with the embodiments 1-3, and simultaneously, SiC/chopped carbon fiber green bodies with higher geometric accuracy and mechanical property can be obtained by optimizing the addition amounts of the chopped carbon fibers and the binder; in addition, compared with the embodiments 1 to 3, the heating temperature and the heat preservation time in the carbonization treatment, the secondary carbonization treatment and the liquid phase siliconizing treatment are further optimized, the cracking deformation and the excessive sintering of the sample can be avoided, the full carbonization and the penetration are realized, and the obtained carbon fiber reinforced SiC ceramic matrix composite material has higher breaking strength and fracture toughness.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a carbon fiber reinforced SiC ceramic matrix composite material through 3D printing is characterized by comprising the following steps:

2. The method for preparing the carbon fiber reinforced SiC ceramic matrix composite material by 3D printing according to claim 1, wherein in the step (a), the specific conditions of the particle size distribution in the SiC powder are as follows: the powder with the particle size of 0.1-2 mu m accounts for 0-5 wt% of the whole SiC powder, the powder with the particle size of 2-40 mu m accounts for 22-55 wt% of the whole SiC powder, and the powder with the particle size of 40-250 mu m accounts for 42-75 wt% of the whole SiC powder.

3. The method for preparing the carbon fiber reinforced SiC ceramic matrix composite material through 3D printing according to claim 1, wherein in the step (a), the diameter of the chopped carbon fiber is 0.1-20 μm, the length-diameter ratio of the chopped carbon fiber is 5-500, and the addition amount of the chopped carbon fiber accounts for 1-20 wt% of the total SiC powder.

4. The method for preparing the carbon fiber reinforced SiC ceramic matrix composite material through 3D printing according to claim 1, wherein in the step (a), the binder is one or more of epoxy resin, phenolic resin or nylon 12, and the addition amount of the binder is 3-20 wt% of SiC powder.

5. The method for preparing the carbon fiber reinforced SiC ceramic matrix composite material by 3D printing according to claim 1, wherein in the step (b), the specific method for carrying out selective laser sintering forming comprises the following steps: and paving powder by adopting a manual or mechanical method, and then irradiating a specific region of the powder bed layer by using laser to obtain the SiC/chopped carbon fiber green body based on slice data obtained by a three-dimensional model of the target forming body.

6. The method for preparing a carbon fiber reinforced SiC ceramic matrix composite material according to claim 1, wherein in the step (c), the organic carbon precursor solution is one or more of an epoxy resin solution, a phenolic resin solution or a pitch solution.

7. The method for preparing the carbon fiber reinforced SiC ceramic matrix composite material by 3D printing according to claim 1, wherein in the step (c), the specific process of the carbonization treatment or the secondary carbonization treatment is as follows: and placing the sample to be carbonized in a non-oxidizing atmosphere, slowly heating the sample within the pyrolysis temperature range of the binder or the carbon precursor, then quickly heating the sample to the target temperature of 850-1100 ℃, and preserving the temperature for 1.0-6 h to carbonize the sample.

8. The 3D printing method for preparing the carbon fiber reinforced SiC ceramic matrix composite material according to any one of claims 1 to 7, wherein in the step (D), the specific process of the liquid phase siliconizing method is as follows: embedding the SiC/chopped carbon fiber/carbon blank in metal Si, heating to a target temperature of 1420-1800 ℃ under a vacuum condition, and preserving heat for 0.25-3 h.

9. A carbon fiber reinforced SiC ceramic matrix composite prepared by the method according to any one of claims 1 to 8.