Preparation method of light-cured 3D printing silicon-based ceramic core with controllable cristobalite content

Abstract

The application relates to a preparation method of a photocured 3D printing silicon-based ceramic core with controllable cristobalite content, which comprises the following steps: preparing a pre-curing agent by mixing a silicon-based ceramic solid-phase powder and a liquid-phase solvent. The silicon-based ceramic solid-phase powder comprises a skeleton support agent, an auxiliary sintering agent and a cristobalite content regulating agent; the liquid-phase solvent comprises a viscosity regulator, an auxiliary curing agent, a powder aggregation inhibitor and a cross-linking auxiliary agent. The pre-curing agent is subjected to a photocured 3D printing process to obtain a ceramic core green body; the ceramic core green body is subjected to a debinding treatment and a sintering treatment to obtain the photocured 3D printing silicon-based ceramic core. The application can accurately regulate the content of cristobalite, reduce the use of the auxiliary sintering agent, simplify the composition of the ceramic core, reduce the number of micro-crack-containing particles in the microstructure of the silicon-based ceramic core material, weaken the stress concentration phenomenon caused by the micro-cracks, improve the high-temperature strength of the ceramic core and better be used for high-temperature alloy casting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of additive manufacturing of ceramic materials, and particularly relates to a preparation method of a light-cured 3D printing silicon-based ceramic core with controllable cristobalite content. BACKGROUND

[0002] Silicon-based ceramic cores are often used in the precision casting of single-crystal hollow turbine blades of aero-engine to prepare hollow high-precision cooling channels of single-crystal high-temperature alloy turbine hollow blades. In order to produce ceramic cores with high performance and high precision, the performance of the ceramic core needs to be precisely controlled, such as the bending strength, thermal stability, dimensional accuracy and thermal shock resistance.

[0003] The cristobalite transformation (fused quartz cristobalite) of the fused quartz in the silicon-based ceramic core has a crucial influence on the performance of the ceramic core. The ceramic core containing a small amount of cristobalite shows poor fire resistance and softens and deforms due to the impact and immersion of the metal liquid during the casting process. When the cristobalite content is too high, the strength of the ceramic core is too high, which causes stress during the solidification of the metal liquid, resulting in recrystallization and other defects of the single-crystal blade. The silicon dioxide-based core material with appropriate cristobalite content can inhibit the softening and shrinkage of the ceramic core at high temperature when used for high-temperature alloy casting.

[0004] At present, there are some methods for controlling cristobalite in industrial production, for example, one is to add auxiliary sintering agents, but the composition of the auxiliary sintering agent is generally complex, it is difficult to accurately control the amount of cristobalite generated, and the introduction of other impurities will affect the high-temperature stability of the ceramic core; two is to change the specific surface area and surface activity of the raw material powder, but the process operation is relatively complex, and there are many different surface states of quartz, it is difficult to ensure the accuracy and batch stability of the powder modification, thereby leading to unstable cristobalite content control in the ceramic core; three is to perform particle size grading, but it is difficult to accurately control the proportion of different particle sizes, and there is a problem of uneven distribution of coarse and fine particles in the grading process; four is to control cristobalite by optimizing the sintering process, but the effect of adjusting the sintering parameters on the cristobalite content is limited.

[0005] In summary, there is an urgent need for a light-cured additive manufacturing silicon-based ceramic core with controllable cristobalite content and a preparation method thereof to further promote the development of the field of ceramic core materials. SUMMARY

[0006] Therefore, the present application provides a preparation method of a light-cured 3D printing silicon-based ceramic core with controllable cristobalite content, and the main purpose is to improve the control accuracy and stability of the cristobalite content.

[0007] In order to achieve the above-mentioned purposes, the present application mainly provides the following technical solutions:

[0008] In one aspect, the present application provides a method for preparing a photocured 3D printed silicon-based ceramic core with controllable cristobalite content, comprising the following steps:

[0009] Preparation of pre-curing agent: 50-60 parts by volume of silicon-based ceramic solid-phase powder and 40-50 parts by volume of liquid-phase solvent are prepared into a pre-curing agent; wherein, the silicon-based ceramic solid-phase powder comprises 80-90 parts by weight of skeleton support agent, 10-20 parts by weight of auxiliary sintering agent, and greater than 0 and less than or equal to 1 part by weight of cristobalite content regulating agent; the liquid-phase solvent comprises 40-60 parts by volume of viscosity adjusting agent, 30-50 parts by volume of auxiliary curing agent, 10-20 parts by volume of powder aggregation inhibitor, and 0-5 parts by volume of cross-linking auxiliary agent;

[0010] Photocured 3D printing process: the pre-curing agent is subjected to a photocured 3D printing process by using a photocured 3D printing technology, to obtain a ceramic core green body;

[0011] Debinding process: the ceramic core green body is subjected to a debinding process, to obtain a debinding-treated ceramic core green body;

[0012] Sintering process: the debinding-treated ceramic core green body is subjected to a sintering process, to obtain a photocured 3D printed silicon-based ceramic core.

[0013] Preferably, in the step of preparing the pre-curing agent, the skeleton support agent is one or more of silica, quartz glass, and fused quartz powder; and / or the auxiliary sintering agent is one or more of zirconium silicate, mullite, zirconia, and alumina; and / or the cristobalite content regulating agent is one or more of potassium oxide, calcium oxide, sodium oxide, iron sesquioxide, magnesium oxide, titanium dioxide, and yttrium sesquioxide.

[0014] Preferably, the skeleton support agent is selected from a powder with a particle size of 5-50 μm; and / or the auxiliary sintering agent is selected from a powder with a particle size of greater than 0 and less than or equal to 12 μm; and / or the cristobalite content regulating agent is selected from a powder with a particle size of greater than 0 and less than or equal to 50 μm.

[0015] Preferably, the viscosity modifier is one or more of 1,6-hexanediol diacrylate, triethylene glycol dimethacrylate (TTEGDMA), polyethylene glycol diacrylate, and ethoxylated bisphenol A diacrylate; and / or the auxiliary curing agent is one or more of trimethylolpropane triacrylate, glycerol propoxylate triacrylate, propoxylated glycerol triacrylate, and pentaerythritol triacrylate; and / or the powder agglomeration inhibitor is one or more of BYK9076, BYK180, BYK111, and AKN2010; and / or the crosslinking auxiliary agent is one or more of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide BAPO, diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide TPO, benzoin diethyl ether BDK, and 1-hydroxycyclohexyl phenyl ketone UV-184; and / or the viscosity of the viscosity modifier is 10-700 mPa.s; and / or the viscosity of the auxiliary curing agent is 100-1000 mPa.s; and / or the viscosity of the crosslinking auxiliary agent is 50-1000 mPa.s.

[0016] Preferably, the step of the photocuring 3D printing process comprises:

[0017] 1) designing a ceramic core three-dimensional model by three-dimensional model design software, slicing the three-dimensional model, and exporting a 3D printing STL file;

[0018] 2) importing the 3D printing STL file into a photocuring 3D printer, setting 3D printing parameters, and performing photocuring 3D printing processing on the pre-curing agent according to the three-dimensional model to obtain a ceramic core green body.

[0019] Preferably, the parameter settings of the photocuring 3D printing process are as follows: the curing thickness is 150-300 μm, the curing power is 25-50 mW / cm 2 , and the single-layer curing time is 5-10 s.

[0020] Preferably, in the step of the debinding process: the ceramic core green body is heated to 700-800 °C in air, and after being kept at a temperature of 700-800 °C for 120-180 min, it is cooled down; preferably, the heating rate is 10-30 °C / h, and the cooling rate is 10-30 °C / h.

[0021] Preferably, in the step of the sintering treatment, the ceramic core blank after the debinding treatment is heated to 1000-1050℃ in air, and kept at 1000-1050℃ for 60-120min, then heated to 1100-1150℃, and kept at 1100-1150℃ for 60-120min, then heated to 1200-1300℃, and kept at 1200-1300℃ for 300-360min, and then cooled down; preferably, the heating rate is 80-120℃ / h, and the cooling rate is 80-120℃ / h.

[0022] In still another aspect, the present application provides a photocured 3D printing silicon-based ceramic core, wherein the photocured 3D printing silicon-based ceramic core is prepared by the method for preparing the photocured 3D printing silicon-based ceramic core with controllable cristobalite content according to any one of the above. The cristobalite content in the silicon-based ceramic core prepared by the present application is in the range of 25-35wt%; the microstructure of the silicon-based ceramic core prepared by the present application contains sufficient pores for easy debinding after pouring, and needs to contain fewer particles containing micro-cracks, and the performance needs to meet the requirements of ceramic cores for pouring, i.e. the room temperature and high temperature (1500-1550℃) bending strength are both higher than 10MPa, and the porosity is greater than 20%.

[0023] Compared with the prior art, the method for preparing the photocured 3D printing silicon-based ceramic core with controllable cristobalite content of the present application has at least the following beneficial effects:

[0024] In one aspect, the embodiment of the present application provides a preparation method of a photocured 3D printing silicon-based ceramic core with controllable cristobalite content, comprising the following steps: preparing 50-60 parts by volume of a silicon-based ceramic solid-phase powder and 40-50 parts by volume of a liquid-phase solvent into a pre-curing agent; wherein, the silicon-based ceramic solid-phase powder comprises 80-90 parts by weight of a skeleton support agent, 10-20 parts by weight of an auxiliary sintering agent, and greater than 0 and less than or equal to 1 part by weight of a cristobalite content regulating agent; the liquid-phase solvent comprises 40-60 parts by volume of a viscosity adjusting agent, 30-50 parts by volume of an auxiliary curing agent, 10-20 parts by volume of a powder aggregation inhibitor, and 0-5 parts by volume of a cross-linking auxiliary agent; performing a photocured 3D printing process on the pre-curing agent by using a photocured 3D printing technology to obtain a ceramic core green body; performing a debinding process on the ceramic core green body to obtain a debinding-treated ceramic core green body; and performing a sintering process on the debinding-treated ceramic core green body to obtain a photocured 3D printing silicon-based ceramic core. It is to be noted that the above method of the present application controls the crystallization degree of fused quartz by controlling the addition amount of the cristobalite content regulating agent, which is dissolved in the microstructure to increase the number of non-bridging oxygen atoms and the diffusion mobility of SiO4 tetrahedron, thereby resulting in a higher crystallization tendency of amorphous silicate grains, which helps to control the crystallization degree of fused quartz within a range beneficial to the performance of the ceramic core. In this embodiment, the content of the cristobalite content regulating agent is adjusted to accurately control the crystallization tendency of amorphous silicate grains in the ceramic core, thereby improving the control accuracy and stability of the cristobalite content.

[0025] Further, the preparation method of the light-cured 3D printing silicon-based ceramic core with controllable cristobalite content provided by the embodiment of the present application is designed as follows: after the ceramic core green body after the debinding treatment is heated to 1000-1050 DEG C in air, and is kept at the temperature of 1000-1050 DEG C for 60-120 min, then continues to be heated to 1100-1150 DEG C, and is kept at the temperature of 1100-1150 DEG C for 60-120 min, then continues to be heated to 1200-1300 DEG C, and is kept at the temperature of 1200-1300 DEG C for 300-360 min and then is cooled. In this way, the cristobalite content is more accurately controlled, the batch stability is better and the operation window is larger by the synergistic control of the cristobalite content regulator and the sintering parameter design. The addition of the cristobalite content regulator reduces the melting point of fused quartz, and in the sintering process at 1100-1250 DEG C, the fused quartz is in a glass state, which promotes viscous flow. The addition of the cristobalite content regulator provides favorable conditions for the nucleation of fused quartz, which promotes the crystallization reaction. The multiple holding times at the high-temperature stage help to occur for a longer time, which promotes the formation of sintering necks between particles. In this way, the content of the cristobalite content regulator and the sintering parameters can both control the crystallization tendency of the amorphous silicate grains in the ceramic core, and adjusting the sintering parameters helps to compensate for the degree and accuracy of the cristobalite content control by the cristobalite content regulator, so that through the synergistic control of the two, the content of cristobalite can be more accurate and stable.

[0026] In summary, the preparation method of the light-cured 3D printing silicon-based ceramic core with controllable cristobalite content provided by the embodiment of the present application can accurately control the cristobalite content, thereby reducing the use of auxiliary sintering agents, simplifying the composition of the ceramic core, reducing the number of particles containing micro-cracks in the microstructure of the silicon-based core material by controlling the cristobalite content, weakening the stress concentration phenomenon caused by micro-cracks, and inhibiting the grain growth, thereby improving the high-temperature strength of the ceramic core and better used for high-temperature alloy casting.

[0027] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and can be implemented according to the content of the specification, the following is a preferred embodiment of the present application and is described in detail below with the help of the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The influence curve of the cristobalite content with the addition of different contents of Fe2O3.

[0029] Figure 2 The influence curve of the cristobalite content with the addition of different contents of CaO in Example 2.

[0030] Figure 3For the embodiment, the three-dimensional model of the ceramic core. DETAILED DESCRIPTION

[0031] To further illustrate the technical means and effects taken by the present application to achieve the intended object, the specific embodiments, structures, features and effects according to the present application are described in detail below in conjunction with the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0032] In one aspect, the present application provides a method for preparing a light-cured 3D printed silicon-based ceramic core with controllable cristobalite content, which comprises the following steps:

[0033] Preparation of pre-curing agent: 50-60 parts by volume of silicon-based ceramic solid-phase powder and 40-50 parts by volume of liquid-phase solvent are prepared into a pre-curing agent; wherein, the silicon-based ceramic solid-phase powder comprises, by weight: 80-90 parts by weight of skeleton support agent, 10-20 parts by weight of auxiliary sintering agent, and greater than 0 and less than or equal to 1 part by weight of cristobalite content regulating agent; the liquid-phase solvent comprises, by volume: 40-60 parts by volume of viscosity adjusting agent, 30-50 parts by volume of auxiliary curing agent, 10-20 parts by volume of powder aggregation inhibitor, and 0-5 parts by volume of cross-linking auxiliary agent.

[0034] Preferably, the skeleton support agent is one or more of silicon dioxide, quartz glass, and fused quartz powder; the auxiliary sintering agent is one or more of zirconium silicate, mullite, zirconia, and aluminum oxide; the cristobalite content regulating agent is one or more of potassium oxide, calcium oxide, sodium oxide, iron sesquioxide, magnesium oxide, and titanium dioxide; the viscosity adjusting agent is one or more of 1,6-hexanediol diacrylate, triethylene glycol dimethacrylate, polyethylene glycol diacrylate, and ethoxylated bisphenol A diacrylate; the auxiliary curing agent is one or more of trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, propoxylated glycerol triacrylate, and pentaerythritol triacrylate; the powder aggregation inhibitor is one or more of BYK9076, BYK180, BYK111, and AKN2010; and the cross-linking auxiliary agent is one or more of BAPO, TPO, BDK, and UV-184.

[0035] Here, a larger viscosity is not conducive to the uniformity of the blade in the printing process, so the viscosity adjusting agent, auxiliary curing agent, and cross-linking auxiliary agent should be selected to have a smaller viscosity, specifically as follows: the viscosity of the viscosity adjusting agent is 10-700 mPa.s; the viscosity of the auxiliary curing agent is 100-1000 mPa.s; and the viscosity of the cross-linking auxiliary agent is 50-1000 mPa.s.

[0036] Preferably, the skeleton proppant is irregular polygonal powder with a particle size of 5-50 μm; the auxiliary sintering agent is rhombic powder with a particle size of 0-12 μm; and the cristobalite content regulating agent is irregular polygonal powder with a particle size of 0-50 μm.

[0037] Preferably, the step of preparing the pre-curing agent comprises:

[0038] 1) mechanically stirring the skeleton proppant, the auxiliary sintering agent and the cristobalite content regulating agent to obtain a silicon-based ceramic solid-phase powder;

[0039] 2) mixing the viscosity regulator, the auxiliary curing agent, the powder agglomeration inhibitor and the cross-linking auxiliary agent to obtain a liquid-phase solvent;

[0040] 3) adding the silicon-based ceramic solid-phase powder into the silicon-based ceramic solid-phase powder to stir and homogenize, thereby obtaining the pre-curing agent.

[0041] The light-curing 3D printing process: using a light-curing 3D printing technology to perform a light-curing 3D printing process on the pre-curing agent, thereby obtaining a ceramic core green body.

[0042] Preferably, in this step: a ceramic core three-dimensional model is designed by using a three-dimensional model design software (such as Figure 3 , but not limited thereto), the three-dimensional model is subjected to a slicing process, and a 3D printing STL file is exported; the STL file is imported into a light-curing 3D printer, 3D printing parameters are set, the pre-curing agent is cured according to the three-dimensional model, and a ceramic core green body is obtained.

[0043] Preferably, the parameters of the light-curing 3D printing process are set as follows: the curing thickness is 150-300 μm, the curing power is 25-50 mW / cm 2 , and the single-layer curing time is 5-10 s.

[0044] The debinding process: performing a debinding process on the ceramic core green body, thereby obtaining a debound ceramic core green body.

[0045] Preferably, the ceramic core green body is heated to 700-800 °C in air, and then cooled after being kept at 700-800 °C for 120-180 min; preferably, the heating rate is 10-30 °C / h, and the cooling rate is 10-30 °C / h.

[0046] The sintering process: performing a sintering process on the debound ceramic core green body, thereby obtaining a light-curing 3D printed silicon-based ceramic core.

[0047] The defatted ceramic core green body is heated to 1000-1050 DEG C in air, and is kept at 1000-1050 DEG C for 60-120 min, then is continuously heated to 1100-1150 DEG C, and is kept at 1100-1150 DEG C for 60-120 min, then is continuously heated to 1200-1300 DEG C, and is kept at 1200-1300 DEG C for 300-360 min, and is then cooled down;

[0048] Preferably, the heating rate is 80-120 DEG C / h, and the cooling rate is 80-120 DEG C / h.

[0049] Here, regarding the above scheme, the following is explained:

[0050] 1) The preparation method of the light-cured 3D printing silicon-based ceramic core with controllable cristobalite content provided by the application controls the crystallization degree of fused quartz by controlling the addition amount of the cristobalite content regulating agent, the cristobalite content regulating agent dissolves in the microstructure, increases the number of non-bridging oxygen atoms and the diffusion mobility of SiO4 tetrahedron, thereby leading to a higher crystallization tendency of amorphous silicate grains, which helps to control the crystallization degree of fused quartz within a range beneficial to the performance of the ceramic core.

[0051] 2) The preparation method of the light-cured 3D printing silicon-based ceramic core with controllable cristobalite content provided by the application controls the cristobalite content more accurately, has better batch stability and a larger operation window through the synergistic control of the cristobalite content regulating agent and sintering parameters. The addition of the cristobalite content regulating agent reduces the melting point of fused quartz, and during the sintering process at 1100-1250 DEG C, the fused quartz is in a glass state, which promotes viscous flow; the addition of the cristobalite content regulating agent provides favorable conditions for the nucleation of fused quartz, promoting the crystallization reaction; multiple holding times at high temperature help to occur for a longer time, promoting the formation of sintering necks between particles.

[0052] 3) The preparation method of the light-cured 3D printing silicon-based ceramic core with controllable cristobalite content provided by the application can accurately regulate the content of cristobalite, thereby reducing the use of auxiliary sintering agents, simplifying the composition of the ceramic core, reducing the number of particles containing micro-cracks in the microstructure of the silicon-based core material by regulating the cristobalite content, weakening the stress concentration phenomenon caused by micro-cracks, and inhibiting grain growth, thereby improving the high-temperature strength of the ceramic core and better used for high-temperature alloy casting.

[0053] The application is further described below through specific embodiments:

[0054] In the following examples and comparative examples, the viscosity of the viscosity modifier is 10-700 mPa·s; the viscosity of the curing aid is 100-1000 mPa·s; and the viscosity of the crosslinking aid is 50-1000 mPa·s.

[0055] Example 1

[0056] This embodiment proposes a method for preparing a photopolymerizable 3D-printed silicon-based ceramic core with controllable cristobalite content. The raw materials used are as follows: 60 parts by volume of silicon-based ceramic solid powder and 40 parts by volume of liquid solvent. Specifically, the silicon-based ceramic solid powder comprises 89.8 parts by weight of a support agent, 10 parts by weight of an auxiliary sintering agent, and 0.2 parts by weight of a cristobalite content regulator. The liquid solvent comprises, by volume fraction, 50 parts by volume of a viscosity modifier, 49 parts by volume of an auxiliary curing agent, 1 part by volume of a crosslinking aid, and 10 parts by volume of a powder agglomeration inhibitor. The skeleton support is made of quartz glass powder with a particle size of 5μm, the auxiliary sintering agent is made of zirconium silicate powder with a particle size of 1μm, the cristobalite content regulator is made of ferric oxide powder with a particle size of 1μm, the viscosity modifier is 1,6-hexanediol diacrylate, the auxiliary curing agent is trimethylolpropane triacrylate, the powder agglomeration inhibitor is dispersant BYK9076, and the crosslinking aid is BAPO.

[0057] The preparation method of this embodiment specifically includes the following steps:

[0058] 1) Weigh quartz glass powder, zirconium silicate powder, and ferric oxide powder, and mechanically stir and mix them evenly to obtain silicon-based ceramic solid-phase mixed powder; mix 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, BYK9076 and photoinitiator BAPO to obtain liquid solvent; add silicon-based ceramic solid-phase mixed powder to liquid solvent for stirring and homogenization to obtain pre-curing agent.

[0059] 2) Design a 3D model of the ceramic core (e.g.) Figure 3 As shown, the 3D model is sliced ​​and exported as a 3D printing STL file. The STL file is then imported into a photopolymer 3D printer, and the 3D printing parameters are set (curing thickness of 200μm, curing power of 40mW / cm). 2 The curing time for a single layer is 10s. The pre-curing agent obtained in step (2) is cured according to the three-dimensional model to obtain a ceramic core blank.

[0060] 3) The ceramic core blank is degreased to obtain a degreased ceramic core blank; wherein, the degreased conditions are as follows: the ceramic core blank is heated to 800℃ in air, and then kept at 800℃ for 120 min before cooling; the heating rate is 20℃ / h and the cooling rate is 20℃ / h.

[0061] 4) sintering the ceramic core green body after the debinding treatment to obtain a photocured 3D printed silicon-based ceramic core green body; wherein the sintering treatment is under the following conditions:

[0062] In air, the ceramic core green body after the debinding treatment is heated to 1050°C, and kept at 1050°C for 60 min, then heated to 1150°C, and kept at 1150°C for 60 min, then heated to 1250°C, and kept at 1250°C for 360 min before cooling; the heating rate is 120°C / h, and the cooling rate is 120°C / h.

[0063] In this embodiment, the cristobalite content in the photocured 3D printed silicon-based ceramic core green body sample is controlled to 27%, at this time the room temperature bending strength is 12.8 MPa, and the high temperature bending strength is 19.6 MPa, which well meets the casting requirements of high-temperature alloy. In addition, the high temperature bending strength test of this embodiment and other embodiments and comparative examples is: keeping at 1500°C for 15 minutes. The specific test method of room temperature bending strength experiment is three-point bending method, and the test method of room temperature bending strength experiment is three-point bending method in a high temperature furnace.

[0064] In addition, Figure 1 To add different content of ferric oxide to the cristobalite content curve. It can be seen that: the addition of a small amount of cristobalite content regulator can control the cristobalite content in a certain range (25-35%), at this time the high temperature performance of the sample is good, and too much addition will significantly increase the cristobalite content, which will promote the expansion of micro-cracks and reduce the performance of the ceramic core.

[0065] Example 2

[0066] This embodiment proposes a preparation method of a photocured 3D printed silicon-based ceramic core with controllable cristobalite content, wherein the raw materials used are as follows: 50 parts by volume of silicon-based ceramic solid phase powder and 50 parts by volume of liquid phase solvent. Among them, the silicon-based ceramic solid phase powder includes: 85 parts by weight of skeleton support agent, 14.8 parts by weight of auxiliary sintering agent, and 0.2 parts by weight of cristobalite content regulator. Among them, the liquid phase solvent includes 60 parts by volume of viscosity regulator, 39 parts by volume of auxiliary curing agent, 1 part by volume of crosslinking auxiliary agent, and 10 parts by volume of powder aggregation inhibitor. Among them, the skeleton support agent selects quartz glass powder with a particle size of 5 μm, the auxiliary sintering agent selects zirconium silicate powder with a particle size of 1 μm, the cristobalite content regulator selects calcium oxide powder with a particle size of 1 μm, the viscosity regulator is triethylene glycol dimethacrylate, the auxiliary curing agent is trimethylolpropane triacrylate, the powder aggregation inhibitor is dispersant BYK111, and the crosslinking auxiliary agent is BAPO.

[0067] The preparation method of this embodiment specifically includes the following steps:

[0068] 1) Weigh out quartz glass powder, zirconium silicate powder, and calcium oxide powder, and mechanically stir and mix them evenly to obtain silicon-based ceramic solid-phase mixed powder; mix triethylene glycol dimethacrylate, trimethylolpropane triacrylate, BYK111 and photoinitiator BAPO to obtain liquid solvent; add silicon-based ceramic solid-phase mixed powder to liquid solvent for stirring and homogenization to obtain pre-curing agent.

[0069] 2) Design a 3D model of the ceramic core (e.g.) Figure 3 As shown, the 3D model is sliced ​​and exported as a 3D printing STL file. The STL file is then imported into a photopolymer 3D printer, and the 3D printing parameters are set (curing thickness of 200μm, curing power of 40mW / cm). 2 The curing time for a single layer is 10s. The pre-curing agent obtained in step (2) is cured according to the three-dimensional model to obtain a ceramic core blank.

[0070] 3) The ceramic core blank is degreased to obtain a degreased ceramic core blank; wherein, the degreased conditions are as follows: the ceramic core blank is heated to 800℃ in air, and then kept at 800℃ for 120 min before cooling; the heating rate is 30℃ / h and the cooling rate is 30℃ / h.

[0071] 4) The degreased ceramic core preform is sintered to obtain a photopolymerizable 3D printing silicon-based ceramic core preform; the sintering conditions are as follows:

[0072] In air, the degreased ceramic core blank is heated to 1000°C and held at 1000°C for 60 min, then heated to 1100°C and held at 1100°C for 60 min, then heated to 1250°C and held at 1250°C for 360 min before cooling down; the heating rate is 100°C / h and the cooling rate is 100°C / h.

[0073] In this embodiment, the cristobalite content in the photopolymer 3D printed silicon-based ceramic core blank sample was adjusted to 32%. At this time, the room temperature bending strength was 11.5 MPa and the high temperature bending strength was 17.8 MPa, which well met the casting requirements of high temperature alloy.

[0074] Figure 2The curves show the effect of adding different amounts of calcium oxide on the quartz content. It can be seen that the addition of a small amount of quartz content regulator can control the quartz content within a certain range (25-35%), at which point the sample exhibits good high-temperature performance. However, excessive addition will significantly increase the quartz content, which will promote the propagation of microcracks and reduce the performance of the ceramic core.

[0075] Example 3

[0076] The raw materials and their mass fractions used in the method described in this embodiment are as follows: 60 parts by volume of silicon-based ceramic solid powder and 40 parts by volume of liquid solvent. The silicon-based ceramic solid powder includes: 84.6 parts by weight of a framework support agent, 15 parts by weight of an auxiliary sintering agent, and 0.4 parts by weight of a cristobalite content regulator. The liquid solvent includes 55 parts by volume of a viscosity modifier, 43 parts by volume of an auxiliary curing agent, 2 parts by volume of a crosslinking aid, and 10 parts by volume of a powder agglomeration inhibitor. Specifically, the framework support agent is quartz glass powder with a particle size of 5 μm, the auxiliary sintering agent is zirconium silicate powder with a particle size of 1 μm, the cristobalite content regulator is yttrium oxide powder with a particle size of 1 μm, the viscosity modifier is 1,6-hexanediol diacrylate, the auxiliary curing agent is trimethylolpropane triacrylate, the powder agglomeration inhibitor is dispersant BYK9076, and the crosslinking aid is TPO.

[0077] A photopolymer additive manufacturing method for silicon-based ceramic cores with controllable cristobalite content and its controllability includes the following steps:

[0078] 1) Weigh quartz glass powder, zirconium silicate powder, and yttrium oxide powder, and mechanically stir and mix them evenly to obtain silicon-based ceramic solid-phase mixed powder; mix 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, BYK9076 and TPO to obtain liquid solvent; add silicon-based ceramic solid-phase mixed powder to liquid solvent for stirring and homogenization to obtain pre-curing agent.

[0079] 2) Design a 3D model of the ceramic core (e.g.) Figure 3 As shown, the 3D model is sliced ​​and exported as a 3D printing STL file. The STL file is then imported into a photopolymer 3D printer, and the 3D printing parameters are set (curing thickness of 200μm, curing power of 40mW / cm). 2 The curing time for a single layer is 10s. The pre-curing agent obtained in step (2) is cured according to the three-dimensional model to obtain a ceramic core blank.

[0080] 3) The ceramic core blank is degreased to obtain a degreased ceramic core blank; wherein, the degreased conditions are as follows: the ceramic core blank is heated to 800℃ in air, and then kept at 800℃ for 120 min before cooling; the heating rate is 20℃ / h and the cooling rate is 20℃ / h.

[0081] 4) sintering the ceramic core green body after the debinding treatment to obtain a photocured 3D printed silicon-based ceramic core green body; wherein the sintering treatment conditions are as follows:

[0082] In air, the ceramic core green body after the debinding treatment is heated to 1050℃, and kept at 1050℃ for 60 min, then heated to 1150℃, and kept at 1150℃ for 60 min, then heated to 1250℃, and kept at 1250℃ for 360 min before cooling; the heating rate is 120℃ / h, and the cooling rate is 120℃ / h.

[0083] In this embodiment, the content of cristobalite in the sample is controlled to 29wt%, at this time the room temperature bending strength is 11.8 MPa, and the high temperature (1500℃) bending strength is 18.8 MPa, which well meets the casting requirements of high-temperature alloy.

[0084] Example 4

[0085] Example 4 proposes a preparation method of a photocured 3D printed silicon-based ceramic core with controllable cristobalite content, wherein the raw materials used are as follows: 60 parts by volume of silicon-based ceramic solid phase powder and 40 parts by volume of liquid phase solvent. Among them, the silicon-based ceramic solid phase powder includes, in parts by weight: 89.8 parts by weight of skeleton support agent, 10 parts by weight of auxiliary sintering agent, and 0.2 parts by weight of cristobalite content control agent; wherein the liquid phase solvent includes, in parts by volume: 47 parts by volume of viscosity adjusting agent, 50 parts by volume of auxiliary curing agent, 3 parts by volume of crosslinking auxiliary agent, and 10 parts by volume of powder aggregation inhibitor. Among them, the skeleton support agent selects quartz glass powder with a particle size of 5μm, the auxiliary sintering agent selects zirconium silicate powder with a particle size of 1μm, the cristobalite content control agent selects iron sesquioxide powder with a particle size of 1μm, the viscosity adjusting agent is 1,6-hexanediol diacrylate, the auxiliary curing agent is trimethylolpropane triacrylate, the powder aggregation inhibitor is BYK9076, and the crosslinking auxiliary agent is BAPO.

[0086] The preparation method of this embodiment specifically includes the following steps:

[0087] 1) Weigh the quartz glass powder, zirconium silicate powder, and iron sesquioxide powder, and mechanically stir to mix uniformly to obtain a silicon-based ceramic solid phase mixed powder; mix 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, BYK9076, and photoinitiator BAPO to obtain a liquid phase solvent; add the silicon-based ceramic solid phase mixed powder into the liquid phase solvent for stirring and homogenization to prepare a pre-curing agent.

[0088] 2) Design a three-dimensional model of the ceramic core (such as Figure 3The three-dimensional model is sliced and processed to export a 3D printing STL file. The STL file is imported into a light-curing 3D printer, and 3D printing parameters (a solidification thickness of 200 pm, a solidification power of 40 mW / cm 2 The pre-curing agent obtained in step (2) is cured according to the three-dimensional model to obtain a ceramic core green body.

[0089] 3) The ceramic core green body is subjected to debinding treatment to obtain a debound ceramic core green body; wherein the debinding treatment conditions are: the ceramic core green body is heated to 800 DEG C in air, and then cooled after being kept at 800 DEG C for 120 min; the heating rate is 20 DEG C / h, and the cooling rate is 20 DEG C / h.

[0090] 4) The debound ceramic core green body is subjected to sintering treatment to obtain a light-curing 3D printing silicon-based ceramic core green body; wherein the sintering treatment conditions are:

[0091] The debound ceramic core green body is heated to 1250 DEG C in air, and then cooled after being kept at 1250 DEG C for 360 min; the heating rate is 120 DEG C / h, and the cooling rate is 120 DEG C / h.

[0092] The sample in Example 4 has a cristobalite content of 14%, a room temperature bending strength of 9.9 MPa, and a high temperature bending strength of 14.3 MPa.

[0093] It should be noted that: Example 4 adopts the most basic inventive concept of the present application, that is, a cristobalite content regulator is added, but it is not a preferred embodiment of the present application because it does not adopt the preferred sintering scheme. The preferred sintering scheme and the cristobalite content regulator have a synergistic effect. Therefore, compared with Example 1, although the cristobalite content regulator is added in Example 4, the multiple holding intervals at the high temperature stage are not set in the sintering step, which will cause the cristobalite content to grow slowly, although the bending strength meets the use requirements, but it is significantly lower than the sample with multiple holding intervals. The results show that: the addition of the cristobalite content regulator and the multiple holding at the high temperature stage in the sintering step both help to promote the formation of cristobalite, and through the synergistic control of the cristobalite content regulator and the sintering parameter design, the cristobalite content is more accurately controlled, the ceramic core performance is better, and the casting demand of the high-temperature alloy is well met.

[0094] Table 1 shows the cristobalite content, bending strength and shrinkage of the ceramic core samples prepared in the above examples and comparative examples.

[0095] Table 1

[0096]

[0097] From Table 1, it can be seen that:

[0098] Embodiments 1-2 of the present application can further control the content of cristobalite in the ceramic core within a beneficial range by designing the sintering process to cooperate with the cristobalite content adjusting agent, while greatly improving the room temperature bending strength and high temperature bending strength of the ceramic core.

[0099] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A method for preparing a photocured 3D printed silica-based ceramic core with controllable cristobalite content, characterized in that, It comprises the following steps: Preparation of pre-curing agent: 50-60 parts by volume of silicon-based ceramic solid phase powder and 40-50 parts by volume of liquid phase solvent are prepared into a pre-curing agent; wherein, the silicon-based ceramic solid phase powder comprises: 80-90 parts by weight of framework support agent, 10-20 parts by weight of auxiliary sintering agent, and greater than 0 and less than or equal to 1 part by weight of cristobalite content regulator; the liquid phase solvent comprises: 40-60 parts by volume of viscosity regulator, 30-50 parts by volume of auxiliary curing agent, 10-20 parts by volume of powder aggregation inhibitor, and 0-5 parts by volume of cross-linking auxiliary agent; Photocuring 3D printing process: using photocuring 3D printing technology to perform photocuring 3D printing process on the pre-curing agent to obtain a ceramic core green body; Degreasing treatment: performing degreasing treatment on the ceramic core green body to obtain a degreasing treated ceramic core green body; Sintering treatment: performing sintering treatment on the degreasing treated ceramic core green body to obtain a photocuring 3D printing silicon-based ceramic core; Wherein, the cristobalite content regulator is one or more of potassium oxide, calcium oxide, sodium oxide, diiron trioxide, magnesium oxide, titanium dioxide, and diyttrium trioxide; Wherein, by adjusting the addition amount of the cristobalite content regulator, the cristobalite content in the photocuring 3D printing silicon-based ceramic core is 25-35wt%; Wherein, in the sintering treatment step: the degreasing treated ceramic core green body is heated to 1000-1050℃ in air, and is kept at 1000-1050℃ for 60-120min, then is continuously heated to 1100-1150℃, and is kept at 1100-1150℃ for 60-120min, then is continuously heated to 1200-1300℃, and is kept at 1200-1300℃ for 300-360min before cooling.

2. The method according to claim 1, wherein the content of cristobalite in the photocured 3D-printed silica-based ceramic core is controlled. In the step of preparing the pre-curing agent: The framework support agent is one or more of silicon dioxide, quartz glass, and fused quartz powder; and / or The auxiliary sintering agent is one or more of zirconium silicate, mullite, zirconia, and di-aluminum trioxide.

3. The method of claim 1, wherein the amount of cristobalite in the photocured 3D printed silica-based ceramic core is controlled by the amount of silica in the photocurable 3D printing silica-based ceramic core precursor. In the step of preparing the pre-curing agent: The framework support agent is selected from powders with a particle size of 5-50μm; and / or The auxiliary sintering agent is selected from powders with a particle size of greater than 0, ≤12μm; and / or The cristobalite content regulator is selected from powders with a particle size of greater than 0, ≤50μm.

4. The method according to claim 1, wherein the content of cristobalite in the photocured 3D-printed silica-based ceramic core is controlled. In the step of preparing the pre-curing agent: The viscosity regulator is one or more of 1,6-hexanediol diacrylate, triethylene glycol dimethacrylate, polyethylene glycol diacrylate, and ethoxylated bisphenol A diacrylate; and / or The auxiliary curing agent is one or more of trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, propoxylated glycerol triacrylate, and pentaerythritol triacrylate; and / or The powder aggregation inhibitor is one or more of BYK9076, BYK180, BYK111, and AKN2010; and / or The cross-linking auxiliary agent is one or more of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide BAPO, diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide TPO, benzoin diethyl ether BDK, and 1-hydroxycyclohexyl phenyl ketone UV-184; and / or The viscosity of the viscosity adjusting agent is 10-700 mPa.s; and / or The viscosity of the auxiliary curing agent is 100-1000 mP.s; and / or The viscosity of the cross-linking auxiliary agent is 50-1000 mPa.s.

5. The method of claim 1, wherein the amount of cristobalite in the photocured 3D printed silica-based ceramic core is controlled. The step of preparing the pre-curing agent comprises: 1) mixing and processing the framework proppant, auxiliary sintering agent, and cristobalite content regulator to obtain a silicon-based ceramic solid-phase powder; 2) mixing and processing the viscosity adjusting agent, auxiliary curing agent, powder agglomeration inhibitor, and cross-linking auxiliary agent to obtain a liquid-phase solvent; 3) adding the silicon-based ceramic solid-phase powder into the liquid-phase solvent for stirring and homogenizing treatment to obtain the pre-curing agent.

6. The method of claim 1, wherein the amount of cristobalite in the photocured 3D printed silica-based ceramic core is controlled. The step of the photocuring 3D printing process comprises: 1) designing a ceramic core three-dimensional model by using a three-dimensional model design software, slicing the three-dimensional model, and exporting a 3D printing STL file; 2) importing the 3D printing STL file into a photocuring 3D printer, setting 3D printing parameters, and performing photocuring 3D printing treatment on the pre-curing agent according to the three-dimensional model to obtain a ceramic core green body.

7. The method of claim 1-6, wherein the content of cristobalite in the photocured 3D printed silica-based ceramic core is controlled by adjusting the content of silica in the photocured 3D printed silica-based ceramic core. The parameter settings of the photocuring 3D printing process are as follows: The curing thickness is 150-300 μm, the curing power is 25-50 mW / cm 2 The single layer curing time is 5-10 s.

8. The method according to claim 1, wherein the content of cristobalite in the photocured 3D-printed silica-based ceramic core is controlled. In the step of the debinding process: The ceramic core green body is heated to 700-800℃ in air, and then cooled after being kept at 700-800℃ for 120-180 min.

9. The method according to claim 8, wherein the content of cristobalite in the photocured 3D-printed silica-based ceramic core is controlled by adjusting the content of silica in the photocured 3D-printed silica-based ceramic core. In the step of the debinding process: the heating rate is 10-30℃ / h, and the cooling rate is 10-30℃ / h.

10. The method of claim 1, wherein the amount of cristobalite in the photocured 3D printed silica-based ceramic core is controlled. In the step of the sintering process: the heating rate is 80-120℃ / h, and the cooling rate is 80-120℃ / h.

11. A photocured 3D printed silicon-based ceramic core, characterized in that, The photocuring 3D printing silicon-based ceramic core is prepared by the method for preparing a photocuring 3D printing silicon-based ceramic core with controllable cristobalite content according to any one of claims 1-10; The cristobalite content in the photocuring 3D printing silicon-based ceramic core is 25-35 wt%.

12. The photocurable 3D printed silicon-based ceramic core according to claim 11, wherein, The photocuring 3D printing silicon-based ceramic core has a porosity greater than 20%.

13. The photocurable 3D printed silicon-based ceramic core according to claim 11, wherein, The photocuring 3D printing silicon-based ceramic core has a room temperature bending strength higher than 10 MPa.

14. The photocuring 3D printing silicon-based ceramic core according to claim 11, wherein: The photocuring 3D printing silicon-based ceramic core has a bending strength higher than 10 MPa at 1500-1550℃.

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