CN116425548B - Adhesive jet printing silicon carbide ceramic composite material based on particle-size distribution powder and preparation method thereof - Google Patents

Abstract

The invention relates to a binder jet printing silicon carbide ceramic composite material based on particle-grade powder and a preparation method thereof. The preparation method comprises the following steps: respectively mixing silicon carbide powder with the median diameter of 20 mu m, silicon carbide powder with the median diameter of 5 mu m, silicon carbide powder with the median diameter of 10 mu m, silicon carbide powder with the median diameter of 50 mu m and silicon carbide powder with the median diameter of 80 mu m to obtain composite powder; wherein, the mass ratio of the silicon carbide powder with the median diameter of 20 mu m, the median diameter of 5 mu m, the median diameter of 10 mu m, the median diameter of 50 mu m and the median diameter of 80 mu m is 150 (50-60): 50-60; spraying and printing the composite powder with a binder to obtain a ceramic blank; debonding the ceramic blank to obtain a ceramic biscuit; and performing reaction sintering siliconizing treatment on the ceramic biscuit to obtain the silicon carbide ceramic composite material.

Description

A binder jet printing silicon carbide ceramic composite based on particle-graded powder Materials and preparation methods

Technical field

The invention belongs to the technical field of silicon carbide ceramic material preparation, and specifically relates to a binder jet printing silicon carbide ceramic composite material modified by particle-graded powder and a preparation method thereof.

Background technique

Silicon carbide ceramics have the characteristics of high strength and hardness, high thermal shock resistance, and low thermal expansion. They have wide application value in the fields of national defense and aerospace, such as microreactors, pressure-resistant shells, optical components, and nuclear energy applications. However, the low fracture reliability of silicon carbide ceramics limits its application scope, especially the preparation of complex-shaped special structures. With the development of science and technology, traditional ceramic molding processes such as slip molding and dry press molding have shortcomings such as single shape and high cost, making it difficult to achieve high-precision, rapid and precise processing of geometrically complex special-shaped silicon carbide ceramic composite materials. , unable to meet the requirements of modern space technology. In view of the above shortcomings, silicon carbide ceramic composite materials based on 3D printing rapid prototyping technology have become a current research hotspot. It is based on a three-dimensional model and controlled by a computer system program to process the powder raw materials layer by layer, stack them, and finally manufacture them. Three-dimensional solid. Compared with traditional material-subtractive manufacturing technology, it has the advantages of integration, rapidity, and personalization, and saves more raw materials. It is currently widely used in fields such as bioengineering, industrial equipment, and transportation.

Binder jet printing (BJ), as a new additive manufacturing method, is suitable for manufacturing high-precision complex components from almost all powders (metals, ceramics and polymers). It sprays the adhesive on the surface of the powder through a nozzle, spreads a new layer of powder on the roller, and repeats the bonding process layer by layer. Compared with fused deposition manufacturing (FDM), it has the advantages of high molding accuracy and fast printing speed; compared with light curing molding (SL), it has the advantages of lower requirements on the powder itself and binder; compared with laser selective Sintering (SLS) has the advantages of lower equipment requirements and higher molding accuracy; compared with direct writing technology (DIW), it has the advantages that the green body is less likely to crack during the curing process. BJ is an important way to mold silicon carbide ceramic composite materials with high precision and complex shapes.

For powder-laying molding technology such as BJ, powder fluidity is an important factor affecting the performance of the molded specimen. Chinese patent CN202210319685 discloses a silicon carbide/carbon/chopped carbon fiber composite powder with good fluidity obtained through ball milling drying or spray granulation. The ceramic green body is formed by BJ and degreased and siliconized to obtain high-density carbonization. Silicon ceramic composites. Since this method is BJ's slurry printing, the slurry preparation steps are cumbersome and a series of factors such as slurry viscosity and solid content need to be considered, which is not friendly to rapid prototyping. Chinese patent CN202210900589 discloses a carbon-containing powder configured into a slurry, which is dried or sprayed and granulated to obtain a composite powder. The blank is printed through BJ molding, debonded, impregnated, solidified, cracked, and finally siliconized. Silicon carbide ceramic material with higher performance. Chopped carbon fiber powder is a rod-shaped cylindrical particle. Due to the large shear force and plane contact points between the particles, its fluidity is poorer than that of nearly spherical silicon carbide particles. As an important material for High-performance ceramic fillers, when mixed with the silicon carbide matrix during the 3D printing process, will reduce the fluidity of the composite powder and have a certain impact on the porosity of the material. Therefore, it is necessary to process the silicon carbide powder to improve its flow. sex.

Contents of the invention

In view of the problems existing in the prior art, the present invention adopts orthogonal experimental design optimization to obtain the optimal fluidity of silicon carbide powder with different particle gradations, and provides a binder jet printing carbonization based on particle gradation powder. Silicon ceramic composite materials and preparation methods thereof.

In a first aspect, the present invention provides a method for preparing silicon carbide ceramic composite materials, including:

(1) Take silicon carbide powder with a median diameter of 20 μm, silicon carbide powder with a median diameter of 5 μm, silicon carbide powder with a median diameter of 10 μm, silicon carbide powder with a median diameter of 50 μm, and Silicon carbide powder with a median diameter of 80 μm is mixed to obtain a composite powder; preferably, the silicon carbide powder with a median diameter of 20 μm, the silicon carbide powder with a median diameter of 5 μm, and the carbonized powder with a median diameter of 10 μm The mass ratio of silicon powder, silicon carbide powder with a median diameter of 50 μm, and silicon carbide powder with a median diameter of 80 μm is 150: (50～60): (50～60): (50～60): ( 50～60);

(2) Perform binder jet printing on the composite powder to obtain a ceramic body;

(3) Debonding the ceramic body to obtain a ceramic green body;

(4) The ceramic blank is subjected to reaction sintering and siliconization treatment to obtain the silicon carbide ceramic composite material.

Preferably, the mixing method is roller ball milling, the rotation speed is 50 to 70 rpm, the ball to material ratio is 1.5 to 2:1, and the ball milling time is 1 to 1.5 hours.

Preferably, the composite powder has a bulk density of 1.01-1.15g/cm ³ , a tap density of 1.50-1.61g/cm ³ , a Carr index of 27.20-35.30, and a Haussner ratio of 1.28-1.68.

Preferably, the parameters of the binder jet printing are: loose powder speed 10~50mm/s, printing layer thickness 20~50μm, roller rotation speed 300~400rpm, and the base layer of powder before printing is set to 15~20 layers , the heater sweeping speed is 15~30mm/s, and the drainage oscillator speed is 2600~3000rpm.

Preferably, the jet binder used in the binder jet printing is an aqueous organic binder with a saturation level of 70 to 75%, and the components of the jet binder include ethylene glycol and ethylene glycol monobutyl ether. and phenolic resin.

Preferably, the debonding temperature is 900-1000°C, and the debonding time is 9-10 hours; the porosity of the ceramic body after debonding is controlled to be 50-70%, and the density is 0.98-1.22g/cm ³ .

Preferably, the mass ratio of silicon powder to ceramic blank in the siliconizing sintering is 1-1.2:1.5-2; the siliconizing sintering temperature is 1500-1600°C, and the siliconizing sintering time is 4-5 hours. .

Preferably, the preparation method also includes impregnating and cracking the ceramic blank at least once between debonding and siliconizing sintering; controlling the density of the ceramic blank after the impregnation and cracking treatment to be 1.73-2.22g/cm ³ and resistant to The flexural strength is 3.59~19.24MPa.

In a second aspect, the present invention provides a silicon carbide ceramic composite material obtained according to the above preparation method. The silicon carbide ceramic composite material has a flexural strength of 235-312MPa, an elastic modulus of 216-301GPa, and a fracture toughness of 1.74 -2.96MPa·m ^1/2 , density is 97-99%.

Beneficial effects:

(1) The present invention obtains composite powders of different particle gradations with good fluidity through orthogonal experimental design ball milling. The preparation of composite powders with excellent performance is conducive to binder jet printing to obtain ceramic blanks with uniform pore distribution, which is beneficial to subsequent The reaction siliconization process produces silicon carbide ceramics with better performance;

(2) Increase the carbon content of the green body through impregnation and cracking treatment, and use reaction sintering in a high-temperature vacuum environment to obtain high-density silicon carbide ceramic composite materials.

Description of drawings

Figure 1 is a schematic diagram of the fluidity test of the composite powder in Example 1;

Figure 2 is an SEM image of the polished surface of the silicon carbide ceramic composite material prepared in Example 1;

Figure 3 is an SEM image of the polished surface of the silicon carbide ceramic composite material prepared in Example 3;

Figure 4 is a schematic diagram of the powder fluidity test in Comparative Example 1;

Figure 5 is an SEM image of the polished surface of the silicon carbide ceramic composite material prepared in Comparative Example 1.

Detailed ways

The present invention is further described through embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

In the present invention, silicon carbide with different particle gradations is used as an investigation factor, Carr Index and Hausner ratio are used as evaluation indicators, and an orthogonal experimental method is used to sieve the powder. Select silicon carbide powder with good flow as the benchmark, and powders with other particle gradations as variable factors. According to the packing density determination method specified in GB/T 16913.3-2008 (Determination of packing density by natural packing method) and ASTM D6393- The tap density measurement method specified in the 99 standard (Carr index) uses the HYL-1001 powder comprehensive characteristic tester to measure the angle of repose, bulk density and tap density of the powder. According to the calculation of the Carr index and Hausner's ratio value formula to obtain the Carr index and Hausner ratio of the composite powder. Among them, the smaller the Carr index and Hausner ratio, the better the fluidity. Measure the fluidity of each group of powders to obtain the powder ratio with the best fluidity. By performing BJ printing on powders of different particle sizes before and after particle gradation, and performing post-processing such as debonding and siliconization on the printed parts, silicon carbide ceramic composite materials with excellent mechanical properties can be obtained.

The following is an exemplary description of the preparation method of the silicon carbide ceramic composite material provided by the present invention. The preparation method may include the following steps.

Ingredients. Take respectively silicon carbide powder with a median diameter of 20 μm (the particle size range can be 15-25 μm), silicon carbide powder with a median diameter of 5 μm (the particle size range can be 2-8 μm), and silicon carbide powder with a median diameter of 10 μm ( Silicon carbide powder with a particle size range of 8-15 μm), silicon carbide powder with a median diameter of 50 μm (a particle size range of 30-60 μm), and silicon carbide powder with a median diameter of 80 μm (a particle size range of 70-70 μm). 100 μm) silicon carbide powder is put into a ball mill grinding jar for ball milling to obtain a uniformly mixed composite powder. Wherein, the silicon carbide powder with a median diameter of 20 μm, the silicon carbide powder with a median diameter of 5 μm, the silicon carbide powder with a median diameter of 10 μm, the silicon carbide powder with a median diameter of 50 μm, and the silicon carbide powder with a median diameter of 50 μm. The mass ratio of silicon carbide powder with a diameter of 80 μm can be 150:(50～60):(50～60):(50～60):(50～60).

Controlling the particle size distribution (PSD) of raw materials through particle gradation. Filling the gaps between large particles with small particles is an important way to obtain lower porosity blanks, which facilitates efficient molding and also affects the post-processing densification and sintering step. Furnace's theory is a typical discontinuous size particle packing theory. This theory believes that the densest packing is formed when small particles just fill the gaps of large particles. If there are three sizes of particles, the medium particles should just fill the gaps of the coarse particles, and the fine particles should fill the gaps of the medium and coarse particles. This extends to the situation of particles of multiple sizes. Affected by 3D printing equipment and existing research foundations, the layer thickness of 3D printing is generally controlled between 0 and 100 μm, which requires that the selection of powder particle size should not be greater than 100 μm, otherwise the printing quality will be reduced. The selection of particle accumulation of multiple sizes is of great significance to the control of the mechanical properties of ceramics. The present invention uses five particle sizes: with a median diameter of 5 and 10 μm as small particles, 20 μm as medium particles, and 50 and 80 μm as large particles for Furnace theory 3 Various sizes of particles are controlled and mixed to prepare powder with good accumulation and fluidity to meet the different performance requirements of ceramics in different fields.

In some embodiments, the ball mill is a roller ball mill, the rotation speed can be 50 to 70 rpm, the ball-to-material ratio can be 1.5 to 2:1, and the ball milling time can be 1 to 1.5 hours. Excessive ball-to-material ratio and too long ball milling time will break the powder, affecting the particle size of the composite powder, causing the later molded powder to be too fine to print successfully; conversely, it will lead to uneven mixing and "inclusion" Phenomenon.

In some embodiments, the bulk density of the composite powder can be controlled to be 1.01-1.15g/cm ³ , the tap density is 1.50-1.61g/cm ³ , the Carr index is 27.20-35.30, and the Hausner ratio is 1.28 -1.68. Preferably, the composite powder has a bulk density of 1.01-1.15g/cm ³ , a tap density of 1.50-1.6g/cm ³ , a Carr index of 27.80-34.94, and a Hausner ratio of 1.38-1.59. Powder under this fluidity parameter can ensure a certain degree of compaction and fluidity, which is beneficial to the flow state of the powder during powder spreading and the compaction of the powder after particle gradation. If the Carr index is too large, the compaction of the powder during grading will be reduced, thereby causing the porosity to be too high; if the Carr index is too small, the fluidity of the powder will be increased and the pressing performance will be reduced, ultimately affecting the quality and quality of the blank. Properties of ceramics after sintering.

Blank printing. The composite powder is subjected to binder jet printing to obtain a ceramic body.

In some embodiments, the parameters of the binder jet printing can be: powder speed 10-50 mm/s, printing layer thickness 20-50 μm, roller rotation speed 300-400 rpm, and the base layer of powder before printing is set to 15 ~20 layers, heater sweeping speed 15~30mm/s, drainage oscillator speed 2600~3000rpm.

In some embodiments, the jet binder used in the binder jet printing is a water-based organic binder, and the components of the jet binder may include ethylene glycol, ethylene glycol monobutyl ether and phenolic resin. This type of binder is suitable for printing high-temperature materials including non-metallic materials such as carbon, tungsten carbide, silicon carbide and other ceramics, with a saturation of 70 to 75%.

The spray binder is an organic binder, which can provide more carbon sources for sintering described later. If the binder saturation is too low, the adhesion between the powders will be weak, thus reducing the performance of the specimen; if the binder saturation is too high, the viscosity will lead to nozzle clogging and affect printing efficiency.

Debonding. The ceramic body is debonded at high temperature to obtain a ceramic green body.

In some embodiments, the debonding temperature can be 900-1000°C, and the debonding time can be 9-10 hours; the porosity of the ceramic body after debonding is controlled to be 50-70%, and the density is 0.98-1.22g/ cm ³ . Maintaining the porosity of the debonded ceramic body between 50 and 70% is conducive to obtaining silicon carbide ceramics for use in various fields through subsequent siliconization processes.

Siliconized sintering. The ceramic blank is subjected to reaction sintering and siliconization treatment to obtain a high-density silicon carbide ceramic composite material.

In some embodiments, the mass ratio of silicon powder to ceramic blank in the siliconized sintering can be controlled to 1-1.2:1.5-2.

In some embodiments, the siliconizing and sintering temperature can be 1500-1600°C, and the siliconizing and sintering time can be 4-5 hours.

Densification is achieved by reactive infiltration. Silicon melts and infiltrates into the pores of the sample, and can react with carbon to form silicon carbide.

In some embodiments, the ceramic green body can also be impregnated and cracked at least once between the debonding and siliconizing sintering. The impregnation and cracking can provide a carbon source for the densification process of the green body, thereby achieving the effect of The function of pre-densification promotes the performance improvement of sintered parts and obtains highly dense silicon carbide ceramic composite materials.

Wherein, the impregnation and cracking process may be as follows: phenolic resin powder and ethanol solution are configured into an impregnation liquid at a mass ratio of 1:1, and the debonded green body is immersed in the impregnation liquid and evacuated, and then placed in the impregnation liquid. Dry in an oven at 120°C for 6 hours to obtain the preform, and then continue to debond, which is consistent with the above debonding process.

In some embodiments, the density of the ceramic green body after impregnation and cracking treatment can be controlled to be 1.73-2.22g/ ^cm3 , and the flexural strength can be controlled to be 3.59-19.24MPa.

The present invention improves the flow characteristics of the composite powder as a whole through gradation compounding and optimization, and increases the density of the printed blank through accumulation of multiple graded powders, thereby also improving the density of the printed blank after debonding. , which is beneficial to the sintering densification of silicon carbide materials. At the same time, through particle gradation, the combination of particles of various thicknesses can also increase the sintering driving force during the densification stage of siliconizing sintering, thereby more effectively promoting densification and improving the performance of the final sintered body.

The silicon carbide ceramic composite material prepared by the invention has a flexural strength of 235-312MPa, an elastic modulus of 216-301GPa, a fracture toughness of 1.74-2.96MPa·m ^1/2 and a density of 97-99%.

Examples are further enumerated below to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above contents of the present invention all belong to the present invention. The protection scope, the specific process parameters of the following examples are only an example of the appropriate range, that is, those skilled in the art can make selections within the appropriate range through the description of this article, and are not limited to the specific numerical values of the examples below.

Example 1

Weigh 150g of silicon carbide with a particle size of 20 μm, 55 g of 5 μm silicon carbide, 60 g of 10 μm silicon carbide, 50 g of 50 μm silicon carbide, and 55 g of 80 μm silicon carbide, put them into a grinding jar of a ball mill, and grind them for 1.5 hours at a ball-to-material ratio of 1.5:1 to obtain a mixture. For uniform composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

High-temperature debonding at 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank;

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Figure 1 is a schematic diagram of the fluidity test of the composite powder in Example 1.

Figure 2 is an SEM image of the polished surface of the silicon carbide ceramic composite material prepared in Example 1.

Example 2

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 50g of 80μm silicon carbide; put them into a ball mill grinding jar with a ball-to-material ratio of 1.5:1, and conduct ball milling for 1.5h to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation treatment with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank;

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Example 3

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 60g of 80μm silicon carbide; put them into a ball mill grinding jar with a ball-to-material ratio of 1.5:1, and conduct ball milling for 1.5h to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Figure 3 is an SEM image of the polished surface of the silicon carbide ceramic composite material prepared in Example 3.

Example 4

Weigh 150g of 20μm silicon carbide, 60g of 5μm silicon carbide, 55g of 10μm silicon carbide, 50g of 50μm silicon carbide and 60g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Example 5

Weigh 150g of 20μm silicon carbide, 60g of 5μm silicon carbide, 60g of 10μm silicon carbide, 55g of 50μm silicon carbide and 50g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Example 6

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 55g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 40 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Example 7

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 55g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 30 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Example 8

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 55g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with an unsaturation of 75%, and set the printing parameters, including a printing layer thickness of 20 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and the basis for spreading powder before printing. The layer is set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Comparative example 1

Weigh 300g of silicon carbide powder with a median diameter of 20 μm, use a powder physical property tester to measure the bulk density and tap density of the powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Figure 4 is a schematic diagram of the powder fluidity test in Comparative Example 1.

Figure 5 is an SEM image of the polished surface of the silicon carbide ceramic composite material prepared in Comparative Example 1.

Comparative example 2

Weigh 300g of silicon carbide powder with a median diameter of 50 μm, use a powder physical property tester to measure the bulk density and tap density of the powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Comparative example 3

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 0g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio. The compressibility of the composite powder of this formula is relatively poor, which is not conducive to the molding described later. The performance of the blank is improved.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Comparative example 4

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 40g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio. The compressibility of the composite powder of this formula is relatively poor, which is not conducive to the molding described later. The performance of the blank is improved. Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Comparative example 5

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 70g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 50 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Comparative example 6

Weigh 150g of 20μm silicon carbide, 55g of 5μm silicon carbide, 60g of 10μm silicon carbide, 50g of 50μm silicon carbide and 55g of 80μm silicon carbide, put them into the grinding jar of a ball mill and grind them for 1.5h at a ball-to-material ratio of 1.5:1 to obtain a uniform mixture. For composite powder, use a powder physical property tester to measure the bulk density and tap density of the composite powder, and calculate the Carr index and Hausner ratio.

Use binder jet printing, select a binder with a saturation of 75%, and set the printing parameters, including a printing layer thickness of 10 μm, a powder speed of 50 mm/s, a roller rotation speed of 300 rpm/min, and a base layer of powder before printing. Set to 20 layers, the heater sweeping speed is 30mm/s, the drainage oscillator speed is 2600rpm/min, and the silicon carbide ceramic body is printed.

Debonding at a high temperature of 900°C, impregnation with phenolic resin ethanol solution at a mass ratio of 1:1, and then debonding to obtain a blank.

Siliconization treatment was performed at 1550°C to obtain high-density silicon carbide ceramic composite materials, and their mechanical properties were tested.

Table 1 below shows the composition of the powders of Examples 1 to 8 and Comparative Examples 1 to 6:

Table 2 below shows the bulk density, tap density, Carr index and Hausner ratio parameter values of the powders of Examples 1 to 8 and Comparative Examples 1 to 6.

sample Bulk density (g/cm ³ ) Tap density (g/cm ³ ) Carr index Hausnaby Example 1 1.105 1.531 27.80 1.38 Example 2 1.092 1.529 28.35 1.40 Example 3 1.104 1.535 27.98 1.39 Example 4 1.047 1.610 34.94 1.54 Example 5 1.099 1.571 30.05 1.43 Example 6 1.105 1.531 27.80 1.38 Example 7 1.105 1.531 27.80 1.38 Example 8 1.105 1.531 27.80 1.38 Comparative example 1 1.058 1.682 37.11 1.59 Comparative example 2 1.139 1.595 28.57 1.40 Comparative example 3 1.021 1.522 33.89 1.49 Comparative example 4 1.078 1.520 29.03 1.41 Comparative example 5 1.101 1.542 28.60 1.40 Comparative example 6 1.105 1.531 27.80 1.38

.

Table 3 below shows the bending strength and other mechanical properties of the molded parts of Examples 1 to 8 and Comparative Examples 1 to 6 after one-time impregnation and cracking and the ceramics after siliconization and densification:

Referring to the data in Table 1-3, it can be seen that compared with the ungraded pure 20μm silicon carbide system, the fluidity after gradation can be significantly improved, and the blanks and ceramics printed with various powder BJ The flexural strength is also higher; from the data of Examples 1 to 3 and Comparative Example 3, it can be seen that the fluidity of the five powders (5 μm, 10 μm, 20 μm, 50 μm, 80 μm) after gradation is better than that of the four powders ( 5μm, 10μm, 20μm, 50μm), the addition of 80μm silicon carbide increases the popularity and compressibility of the powder, and promotes the performance of the molded blank; secondly, after grading the powder BJ printing blank and In terms of ceramic performance, there is also a direct relationship between fluidity and performance. After one PIP treatment, the best performance of the blank can reach 19.2MPa, the best ceramic performance can reach 285MPa, the elastic modulus can reach 278GPa, and the fracture toughness can reach 2.24 MPa·m ^{1 /2} , corresponding to the group of powders with the best fluidity.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (9)

1. A method for preparing a silicon carbide ceramic composite material, comprising the steps of:

(1) Respectively mixing silicon carbide powder with the median diameter of 20 mu m, silicon carbide powder with the median diameter of 5 mu m, silicon carbide powder with the median diameter of 10 mu m, silicon carbide powder with the median diameter of 50 mu m and silicon carbide powder with the median diameter of 80 mu m to obtain composite powder; wherein the mass ratio of the silicon carbide powder with the median diameter of 20 mu m to the silicon carbide powder with the median diameter of 5 mu m to the silicon carbide powder with the median diameter of 10 mu m to the silicon carbide powder with the median diameter of 50 mu m to the silicon carbide powder with the median diameter of 80 mu m is 150 (50-60): 50-60;

(2) Spraying and printing the composite powder with a binder to obtain a ceramic blank;

(3) Debonding the ceramic blank to obtain a ceramic biscuit;

(4) And performing reaction sintering siliconizing treatment on the ceramic biscuit to obtain the silicon carbide ceramic composite material.

2. The preparation method according to claim 1, wherein the mixing mode is roller ball milling, the rotating speed is 50-70 r/min, the ball-to-material ratio is 1.5-2:1, and the ball milling time is 1-1.5 h.

3. The method according to claim 1, wherein the process comprisesThe bulk density of the composite powder is 1.01-1.15g/cm ³ Tap density of 1.50-1.61g/cm ³ The Calf index is 27.20-35.30, and the Haoshan ratio is 1.28-1.68.

4. The method of claim 1, wherein the parameters of the binder jet printing are: the powder scattering speed is 10-50 mm/s, the printing layer thickness is 20-50 mu m, the roller rotating speed is 300-400 rpm, the base layer for paving powder before printing is set to 15-20 layers, the heater sweeping speed is 15-30 mm/s, and the drainage oscillator speed is 2600-3000 rpm.

5. The method according to claim 1, wherein the binder is aqueous organic binder having a saturation of 70-75% and used for the binder jet printing, and the components of the binder include ethylene glycol, ethylene glycol monobutyl ether and phenolic resin.

6. The preparation method according to claim 1, wherein the debonding temperature is 900-1000 ℃ and the debonding time is 9-10 hours; the porosity of the ceramic body after the debonding is controlled to be 50 to 70 percent and the density is controlled to be 0.98 to 1.22g/cm ³ 。

7. The preparation method according to claim 1, wherein the mass ratio of the silicon powder to the ceramic biscuit in the siliconizing sintering is 1-1.2:1.5-2; the siliconizing sintering temperature is 1500-1600 ℃, and the siliconizing sintering time is 4-5h.

8. The method of claim 1, further comprising dip cracking the ceramic greenware at least once between debinding and siliconizing sintering; the density of the ceramic biscuit after the dipping and cracking treatment is controlled to be 1.73-2.22 g/cm ³ The bending strength is 3.59-19.24 MPa.

9. A silicon carbide ceramic composite material obtained by the preparation method according to claim 1, which is characterized in thatThe bending strength of the silicon carbide ceramic composite material is 235-312MPa, the elastic modulus is 216-301GPa, and the fracture toughness is 1.74-2.96MPa m ^1/2 The density is 97-99%.