Silicified graphite material, silicified graphite casting mold and preparation method of silicified graphite casting mold

Abstract

The invention provides a silicified graphite material, a silicified graphite casting mold and a preparation method of the silicified graphite casting mold, and relates to the technical field of nickel-based high-temperature alloy and titanium alloy casting. The silicified graphite material provided by the invention comprises a porous graphite matrix and a silicon carbide layer wrapping the surface of the porous graphite matrix, the porous graphite substrate has a hierarchical porous structure, the hierarchical porous structure comprises closed holes and penetrating holes, the aperture of the closed holes is 0.001-0.05 mm, the penetrating holes penetrate through the porous graphite substrate, and the penetrating holes comprise first-level penetrating holes with the aperture of 0.03-0.2 mm and second-level penetrating holes with the aperture of 0.1-1 mm; and the silicon carbide layer uniformly wraps the external surface of the hierarchical porous graphite matrix and the surfaces of the internal through holes. The silicified graphite material not only has good thermal stability and thermal conductivity, but also has good high-temperature oxidation resistance, good corrosion resistance, high mechanical strength, excellent air permeability and good dimensional stability.

Description

Technical Field

[0001] This application claims priority based on the Chinese patent application filed on December 31, 2024, with application number "202411993089.6" and title "A graphite-based casting mold and preparation method thereof". All of these are incorporated into this application for reference.

[0002] The invention belongs to the field of nickel-based high-temperature alloy and titanium alloy casting, and specifically relates to a silicified graphite material, a silicified graphite casting mold and a preparation method thereof. Background Art

[0003] Nickel-based superalloys and titanium alloys have good comprehensive properties and are widely used in aviation, aerospace, ships, weapons, petrochemicals and other fields. With the rapid development of related fields, the demand for nickel-based superalloys and titanium alloy parts with complex cavities is increasing.

[0004] The casting process combines mold design and shape control technology to achieve the integral forming of complex structure nickel-based high-temperature alloy and titanium alloy parts. Graphite does not react chemically with nickel-based high-temperature alloy and titanium alloy, and has good thermal conductivity and thermal stability, making it one of the more commonly used casting mold materials. However, graphite materials have poor oxidation corrosion resistance and high brittleness at high temperatures. At the same time, due to the poor chilling effect and yield of graphite, machined graphite molds are prone to many defects on the surface of castings (such as cracks, cold shuts, flow marks, etc.), and product quality is difficult to guarantee, which is not suitable for large-scale production of complex-shaped castings. For parts with complex structures and cavities, their shape control cores also have complex structures accordingly, so it is difficult to remove traditional graphite cores using conventional machining methods. In addition, with the increase in the size of castings, especially for large, complex, thin-walled castings, the importance of air permeability becomes particularly prominent. Therefore, it is necessary to use a mold with excellent air permeability to ensure the smooth progress of the casting process. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a silicified graphite material, a silicified graphite casting mold and a preparation method thereof. The silicified graphite material not only has good thermal stability and thermal conductivity, but also has good high-temperature oxidation resistance, good corrosion resistance, high mechanical strength, excellent air permeability and good dimensional stability.

[0006] The specific technical solutions of the present invention are as follows: In the first aspect, the present invention provides a silicified graphite material, comprising a multi-level porous graphite matrix and a silicon carbide layer wrapped on the surface of the multi-level porous graphite matrix; the multi-level porous graphite matrix has a hierarchical porous structure, the hierarchical porous structure comprises closed holes and through holes, the closed holes are non-penetrating holes, the pore size of the closed holes is 0.001-0.05 mm, the through holes penetrate the multi-level porous graphite matrix, the through holes include first-level through holes and second-level through holes, the pore size of the first-level through holes is 0.03-0.2 mm, the pore size of the second-level through holes is 0.1-1 mm, and the silicon carbide layer is uniformly wrapped on the outer surface of the multi-level porous graphite matrix and the surface of the inner through holes.

[0007] The silicified graphite material provided by the present invention provides a rich pore size by adopting a multi-level pore graphite matrix with a pore structure of different sizes. By controlling the number and distribution area of ​​the closed holes with a pore size of 0.001-0.05 mm, the thermal conductivity of the local area of ​​the material can be adjusted, and then the cooling rate of the local area of ​​the casting during casting can be controlled, the temperature field of the casting can be adjusted, the thermal stress defects of the casting can be reduced, and the chilling effect of the silicified graphite material can be improved. The structural strength can also be improved by optimizing the distribution of the closed holes to ensure that the silicified graphite material has sufficient resistance to the impact of metal liquid during the casting process. At the same time, the closed holes also provide a certain compression capacity for the silicified graphite material, provide a certain space for the volume of the casting to shrink during the cooling and solidification process, and improve the yield of the silicified graphite material. The first through hole with a pore size of 0.03-0.2 mm and the second through hole with a pore size of 0.1-1 mm constitute an effective gas channel, so that the silicified graphite material has excellent air permeability, which is conducive to the smooth discharge of a large amount of gas (such as air, steam generated by water evaporation, etc.) generated after the high-temperature molten metal is poured into the mold. The silicon carbide layer wrapping the multi-level porous graphite matrix can effectively prevent the oxidizing atmosphere and / or high-temperature molten metal from corroding the silicified graphite material during the casting process, and further improve its dimensional stability and mechanical strength.

[0008] Furthermore, the second level through-holes are prepared by additive manufacturing technology. The use of additive manufacturing technology can adjust the pore size and distribution in the multi-level porous graphite matrix according to the needs of the actual application scenario, and the internal pore structure can be prepared simultaneously during the graphite-based casting molding process by additive manufacturing technology, avoiding the risk of low strength of the graphite casting and easy damage during machining in the prior art.

[0009] Furthermore, in the multi-level porous graphite matrix, the closed pores and the through pores are arranged in at least one of a parallel combination, a series combination, a modular combination, a hierarchical combination, and a network combination. By adopting the above combination, the distribution of the pores is adjusted, and thus the thermal conductivity, strength, etc. of the local area of ​​the silicified graphite material are adjusted, so that the needs for the casting mold in practical applications can be met.

[0010] Furthermore, the parallel combination, the series combination, the modular combination, the hierarchical combination and the network combination are achieved by adjusting the additive manufacturing process, and the process includes at least one of model slicing processing method, layer thickness, filler spacing, filler method, slurry extrusion speed, slurry extrusion pressure, extrusion head size, nozzle resolution, ink drop size, inkjet pressure, laser power, spot size, scanning speed, printing path, temperature, humidity and protective gas.

[0011] In a possible implementation, the thickness of the silicon carbide layer is 0.05-5 mm. By controlling the thickness of the silicon carbide layer, the corrosion of the silicified graphite casting material by the oxidizing atmosphere and high-temperature molten metal during the casting process can be effectively prevented, thereby improving its dimensional stability and mechanical strength.

[0012] In a second aspect, the present invention provides a silicified graphite casting mold, wherein the material composition of the silicified graphite casting mold includes the above-mentioned silicified graphite material.

[0013] Furthermore, the siliconized graphite casting mold comprises a core, a shell, a casting component, an exhaust component and a guide component, and at least one of the core, the shell, the casting component and the exhaust component uses the siliconized graphite material described in any one of claims 1-5.

[0014] In a third aspect, the present invention provides a method for preparing the above-mentioned silicified graphite casting, comprising the following steps: S1. Modeling: According to the functional requirements of the siliconized graphite casting, a combination of closed pores and through pores in the corresponding hierarchical porous structure is designed, and a three-dimensional model of a graphite matrix having the hierarchical porous structure is constructed; S2, mixed raw material preparation: the carbon source, the binder, the auxiliary agent and the solvent are fully mixed to form a mixed slurry; the mass ratio of the carbon source, the binder, the auxiliary agent and the solvent is (60-90): (0-40): (0-10): (30-100); S3, blank manufacturing: importing the three-dimensional model described in step S1 into the control module of the additive manufacturing equipment, adding the mixed slurry described in step S2 into the hopper of the additive manufacturing equipment, and performing three-dimensional printing to obtain a blank of a multi-level porous graphite matrix; S4, high temperature treatment: the green body of the multi-level porous graphite matrix in step S3 is subjected to carbonization treatment and graphitization treatment in sequence, and then subjected to siliconization treatment to form a silicon carbide layer, and then selectively subjected to silicon removal treatment to obtain a siliconized graphite casting mold.

[0015] The preparation method of the silicified graphite mold provided by the present invention controls the ratio of the mixed raw materials so that the closed pores and the first-level penetration holes of the mixed raw materials are present in the printed graphite matrix, and the second-level penetration holes are designed in the three-dimensional model of the graphite matrix by modeling, and then by subsequent three-dimensional printing, while printing the graphite matrix, the second-level penetration holes are formed in its internal structure, and the silicified graphite mold with a multi-level pore structure that meets the design requirements is prepared. At the same time, in the preparation process of the silicified graphite mold, the penetration hole is the channel and reaction area for the raw materials for silicification to enter the multi-level pore graphite matrix. In addition, the preparation method of the silicified graphite mold provided by the present invention can prepare a graphite-based mold with rich pore size, controllable pore size and pore size distribution, which overcomes the drawbacks of the existing preparation method such as single pore size, difficult to control pore size, uneven pore distribution and easy to cause closed pores, which leads to the single function and low material transfer efficiency of the graphite-based mold. And the preparation method provided by the present invention is simple and controllable, which is conducive to large-scale industrial production.

[0016] In a possible implementation manner, the combination method in step S1 is a parallel combination or a hierarchical combination of the closed holes and the penetrating holes.

[0017] In a possible implementation, the preparation process of the mixed raw material in step S2 further includes granulation, that is, spheroidizing and granulating the mixed slurry to obtain a mixed material. Spheroidizing and granulating can provide the mixed raw material with more closed pores and first-level penetrating pores.

[0018] In a possible implementation, the carbon source in step S2 includes at least one of natural graphite powder, isostatically pressed graphite powder, graphite electrode powder, asphalt coke, petroleum coke, metallurgical coke and carbon black.

[0019] In a possible implementation, the binder in step S2 includes at least one of epoxy resin, phenolic resin, furan resin, urea-formaldehyde resin, polyurethane, polyvinyl alcohol, polymethyl methacrylate and polyvinyl butyral.

[0020] In a possible implementation manner, the auxiliary agent in step S2 includes at least one of a curing agent, a sintering aid, a dispersant and a diluent.

[0021] In a possible implementation, the solvent in step S2 includes at least one of water, methanol, ethanol, acetone, ethylene glycol, xylene, ethyl acetate and petroleum ether.

[0022] In a possible implementation manner, the three-dimensional printing in step S3 adopts any one of slurry extrusion technology, three-dimensional printing technology, powder laser solidification technology and selective laser sintering technology; In a possible implementation manner, the silicidation treatment in step S4 adopts any one of chemical vapor infiltration, chemical vapor deposition, chemical vapor reaction and liquid silicon infiltration.

[0023] In a possible implementation, the desiliconization treatment in step S4 adopts a molten alkali desiliconization method or a high temperature volatilization desiliconization method. Through the desiliconization treatment, the unreacted excess silicon on the surface and / or through-holes of the casting after the silicification treatment can be removed to prevent the pores from being blocked, thereby further improving the air permeability of the casting.

[0024] Based on the common knowledge in this field, the above-mentioned implementation modes can be combined arbitrarily.

[0025] The reagents and raw materials used in the present invention are commercially available.

[0026] The positive and progressive effects of the present invention are: The silicified graphite material provided by the present invention has a pore structure of different sizes, provides a rich pore size, and through different combination strategies of closed pores and through pores, a silicified graphite-based casting material that meets multiple functional requirements such as local adjustment of thermal conductivity and local adjustment of strength can be obtained. The silicified graphite material has good resistance to high-temperature oxidation and corrosion, excellent air permeability, good dimensional stability and good mechanical strength. The preparation method of the silicified graphite casting provided by the present invention is simple and controllable, which is conducive to large-scale industrial production. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0028] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0029] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventionally understood meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments is carried out in accordance with the protocols and parameters given by the manufacturer.

[0030] Example 1

[0031] The present embodiment provides a silicified graphite material, which includes a multi-level porous graphite matrix and a silicon carbide layer wrapped on the surface of the multi-level porous graphite matrix. The multi-level porous graphite matrix is ​​evenly divided into three layers from the inside to the outside, wherein the inner layer and the outer layer are small-pore porous graphite, the small-pore porous graphite has closed holes with an average pore size of 0.003 mm and first-level penetration holes with an average pore size of 0.08 mm, and the middle layer is large-pore porous graphite. In addition to the closed holes with an average pore size of 0.003 mm and the first-level penetration holes with an average pore size of 0.08 mm, the structure of the large-pore porous graphite also has second-level penetration holes with a designed pore size of 1 mm. The second-level penetration holes in the large-pore porous graphite are connected with the first-level penetration holes in the small-pore porous graphite and penetrate the multi-level porous graphite matrix. The silicon carbide layer is evenly wrapped on the outer surface of the multi-level porous graphite matrix and the surface of the inner penetration holes, and the average thickness of the silicon carbide layer is 0.1 mm.

[0032] This embodiment also provides a silicified graphite casting mold for preparing a titanium alloy pipe. The shell and core of the silicified graphite casting mold are made of the silicified graphite material provided in this embodiment, which is prepared by the following preparation method: S1. Modeling: Design and draw drawings of the silicified graphite casting mold according to the shape and size of the titanium alloy pipe to be prepared and the functional requirements of the silicified graphite casting mold, and then construct the designed drawings into a three-dimensional model; S2, mixed material preparation: carbon source: binder: auxiliary agent: solvent according to the mass ratio of 75:10:6:66, put into a blender and mix thoroughly to form a mixed slurry; wherein the carbon source is composed of isostatically pressed graphite powder and carbon black in a mass ratio of 1:1, the binder is polyvinyl alcohol, the auxiliary agent is a water-soluble sol, and the solvent is water; S3, blank manufacturing: the three-dimensional model in step S1 is introduced into the slurry extrusion equipment, the mixed slurry in step S2 is loaded into the hopper of the slurry extrusion equipment, and the process conditions are set as follows: the model is sliced ​​automatically, the layer thickness is 0.3 mm, the extrusion head diameter is 0.4 mm, the filler interval is 0.4 mm, and the working temperature is 45°C. The extruded wire is deposited and solidified along the set path, and continuous pores with a diameter of 0.1 mm are formed between the angles of the wires, and then accumulated layer by layer to prepare a blank with a multi-level porous graphite matrix; S4, high temperature treatment: After the green body of the multi-level porous graphite matrix obtained in step S3 is subjected to carbonization treatment and graphitization treatment in sequence, a silicon carbide layer is deposited by chemical vapor deposition to obtain a silicified graphite casting mold.

[0033] Example 2

[0034] The present embodiment provides a silicified graphite material, which includes a multi-level porous graphite matrix and a silicon carbide layer wrapped on the surface of the multi-level porous graphite matrix, wherein the multi-level porous graphite matrix has a plurality of Class A regions and a plurality of Class B regions in a checkerboard pattern, wherein the Class A regions and the Class B regions are arranged alternately, wherein the Class A regions have closed holes with an aperture of 0.005 mm and first-level through holes with an aperture of 0.05 mm, and the Class B regions have second-level through holes with an aperture of 0.5 mm in addition to closed holes with an aperture of 0.005 mm and first-level through holes with an aperture of 0.05 mm, and the distribution density of the second-level through holes increases stepwise from the center to the edge of the Class B regions; the silicon carbide layer is uniformly wrapped on the outer surface of the multi-level porous graphite matrix and the surface of the inner through holes, and the average thickness of the silicon carbide layer is 0.2 mm.

[0035] This embodiment also provides a silicified graphite mold for preparing a nickel-tungsten alloy concave plate. The shell, core and casting components of the silicified graphite mold are made of the silicified graphite material provided in this embodiment, which is prepared by the following preparation method: S1. Modeling: Design and draw drawings of the silicified graphite casting mold according to the shape and size of the nickel-tungsten alloy concave plate to be prepared and the functional requirements of the silicified graphite casting mold, and then construct the designed drawings into a three-dimensional model; S2, mixed material preparation: carbon source: binder: auxiliary agent: solvent according to the mass ratio of 85:30:8:96, put into a blender and fully mix to form a mixed slurry, and then spheroidize and granulate to obtain a mixed material; wherein the carbon source is composed of natural graphite powder and petroleum coke in a mass ratio of 5:2, the binder is phenolic resin, the auxiliary agent is an amine curing agent, and the solvent is ethanol; S3, blank manufacturing: the three-dimensional model in step S1 is introduced into the powder laser curing equipment, and the mixed material in step S2 is loaded into the equipment hopper. The process conditions adopted are: the model is sliced ​​manually, the layer thickness is 0.15 mm, the spot size is 0.2 mm, the laser power is 25 W, the laser scanning speed is 900 mm / s, the working temperature is 75 ° C, and N2 is filled as a protective gas in the operating space; during the blank manufacturing process, the laser filling interval from the center of area B to the edge of area B in the model is gradually increased from 0.2 mm to 0.5 mm, so as to achieve a step-by-step increase in the distribution density of the 0.5 mm second-level penetration holes, and obtain a blank with a multi-level hole graphite matrix; S4, high temperature treatment: the green body of the multi-level porous graphite matrix obtained in step S3 is subjected to carbonization treatment and graphitization treatment in sequence, a silicon carbide layer is prepared by liquid silicon infiltration method, and then silicon removal treatment is performed by high temperature volatilization method to obtain a siliconized graphite casting mold.

[0036] Example 3

[0037] The present embodiment provides a material for silicification of graphite, which includes a multi-level porous graphite matrix and a silicon carbide layer wrapped on the surface of the multi-level porous graphite matrix, the multi-level porous graphite matrix is ​​divided into two layers from the inside to the outside, the outer layer has evenly distributed closed holes and first-level through holes, the average diameter of the closed holes is 0.001 mm, and the average diameter of the first-level through holes is 0.03 mm, the inner layer has a network structure formed by a network combination of a core skeleton and ribs, the core skeleton has closed holes with an average pore size of 0.001 mm, and first-level through holes with an average pore size of 0.03 mm, which plays a self-supporting role, and the closed holes and the first-level through holes are evenly distributed on the skeleton; the ribs are wrapped or involved around the core skeleton, and the ribs have closed holes with an average pore size of 0.001 mm and an average pore size of 0.03 mm. In addition to the first-level penetration holes of mm, there are also second-level penetration holes with an average pore size of 0.8mm. The closed holes, first-level penetration holes and second-level penetration holes are evenly distributed on the ribs. The silicon carbide layer is evenly wrapped on the outer surface of the multi-level porous graphite matrix and the surface of the internal penetration holes, and the average thickness of the silicon carbide layer is 0.1mm.

[0038] This embodiment also provides a silicified graphite mold for preparing titanium-magnesium alloy space lattice foam structural components. The shell, core, casting component, exhaust component and guide component of the silicified graphite mold are all made of the silicified graphite material provided in this embodiment, which is prepared by the following preparation method: S1. Modeling: Design and draw drawings of the silicified graphite casting mold according to the shape and size of the titanium-magnesium alloy space lattice foam structural components to be prepared and the functional requirements of the silicified graphite casting mold, and then construct the designed drawings into a three-dimensional model; S2, mixed material preparation: carbon source: curing agent: solvent according to the mass ratio of 95:5:40, put into a blender and mix thoroughly to form a mixed slurry, and then spheroidize and granulate to obtain a mixed material; wherein the carbon source is composed of pitch coke, graphite electrode powder and carbon black in a mass ratio of 5:1:3, the curing agent is p-toluenesulfonic acid, and the solvent is water; S3, blank manufacturing: the three-dimensional model in step S1 is introduced into the three-dimensional printing equipment, the mixed material in step S2 is loaded into the equipment hopper, and the process conditions of the three-dimensional printing are set as follows: the ink sprayed is furan resin, the core skeleton area is 1200PDI inkjet resolution, and the rib area is 400PDI inkjet resolution, so as to obtain a blank with a multi-level porous graphite matrix; S4, high temperature treatment: the green body of the multi-level porous graphite matrix obtained in step S3 is subjected to carbonization treatment and graphitization treatment in sequence, a silicon carbide layer is prepared by chemical vapor infiltration, and then a molten alkali method is used to remove silicon to obtain a silicified graphite casting.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicified graphite material, characterized in that: The invention comprises a multi-level porous graphite matrix and a silicon carbide layer wrapped on the surface of the multi-level porous graphite matrix, wherein the multi-level porous graphite matrix has a hierarchical porous structure, wherein the hierarchical porous structure comprises closed holes and through holes, wherein the closed holes are non-penetrating holes, and the pore size of the closed holes is 0.001-0.05 mm, and the through holes penetrate the multi-level porous graphite matrix, wherein the through holes comprise first-level through holes and second-level through holes, wherein the pore size of the first-level through holes is 0.03-0.2 mm, and the pore size of the second-level through holes is 0.1-2 mm, and the silicon carbide layer is uniformly wrapped on the outer surface of the multi-level porous graphite matrix and the inner surface of the through holes.

2. The silicified graphite material according to claim 1, characterized in that: The second level penetration holes are prepared by additive manufacturing technology.

3. The silicified graphite material according to claim 2, characterized in that: In the multi-level porous graphite matrix, the closed pores and the through pores are in at least one of a parallel combination, a series combination, a modular combination, a hierarchical combination and a network combination.

4. The silicified graphite material according to claim 3, characterized in that: The parallel combination, the series combination, the modular combination, the hierarchical combination and the network combination are realized by adjusting the process of the additive manufacturing technology, and the process includes at least one of model slicing processing method, layer thickness, filler spacing, filler method, slurry extrusion speed, slurry extrusion pressure, extrusion head size, nozzle resolution, ink drop size, inkjet pressure, laser power, spot size, scanning speed, printing path, temperature, humidity and protective gas.

5. The silicified graphite material according to claim 1, characterized in that: The thickness of the silicon carbide layer is 0.05-5 mm.

6. A silicified graphite casting mold, characterized in that: The material composition of the silicified graphite casting mold includes the silicified graphite material described in any one of claims 1-5.

7. The silicified graphite casting mold according to claim 6, characterized in that: The siliconized graphite casting mold comprises a core, a shell, a casting component, an exhaust component and a guide component, and at least one of the core, the shell, the casting component, the exhaust component and the guide component uses the siliconized graphite material described in any one of claims 1-5.

8. A method for preparing the silicified graphite casting mold according to claim 6 or 7, characterized in that: The following steps are involved: S1. Modeling: According to the functional requirements of the siliconized graphite casting, a combination of closed pores and through pores in the corresponding hierarchical porous structure is designed, and a three-dimensional model of a graphite matrix having the hierarchical porous structure is constructed; S2, mixed raw material preparation: the carbon source, the binder, the auxiliary agent and the solvent are fully mixed to form a mixed slurry; the mass ratio of the carbon source, the binder, the auxiliary agent and the solvent is (60-90): (0-40): (0-10): (30-100); S3, blank manufacturing: importing the three-dimensional model described in step S1 into the control module of the additive manufacturing equipment, adding the mixed slurry described in step S2 into the hopper of the additive manufacturing equipment, and performing three-dimensional printing to obtain a blank of a multi-level porous graphite matrix; S4, high temperature treatment: the green body of the multi-level porous graphite matrix in step S3 is subjected to carbonization treatment and graphitization treatment in sequence, and then subjected to siliconization treatment to form a silicon carbide layer, and then selectively subjected to silicon removal treatment to obtain a siliconized graphite casting mold.

9. The method for preparing the silicified graphite casting mold according to claim 8, characterized in that: The combination method in step S1 is a parallel combination or a hierarchical combination of the closed holes and the penetrating holes.

10. The method for preparing the silicified graphite casting mold according to claim 8, characterized in that: The preparation process of the mixed raw material in step S2 further includes granulation, that is, spheroidizing and granulating the mixed slurry to obtain a mixed material; And / or, the carbon source in step S2 includes at least one of natural graphite powder, isostatic graphite powder, graphite electrode powder, asphalt coke, petroleum coke, metallurgical coke and carbon black; And / or, the binder in step S2 includes at least one of epoxy resin, phenolic resin, furan resin, urea-formaldehyde resin, polyurethane, polyvinyl alcohol, polymethyl methacrylate and polyvinyl butyral; And / or, the auxiliary agent in step S2 includes at least one of a curing agent, a sintering aid, a dispersant and a diluent; And / or, the solvent in step S2 includes at least one of water, methanol, ethanol, acetone, ethylene glycol, xylene, ethyl acetate and petroleum ether; And / or, the three-dimensional printing in step S3 adopts any one of slurry extrusion technology, three-dimensional printing technology, powder laser solidification technology and selective laser sintering technology; And / or, the silicidation treatment in step S4 adopts any one of chemical vapor infiltration, chemical vapor deposition, chemical vapor reaction and liquid silicon infiltration; And / or, the desiliconization treatment in step S4 adopts a molten alkali desiliconization method or a high temperature volatilization desiliconization method.