Preparation method of high-dimensional-precision ceramic core and casting forming method

Abstract

The invention relates to the technical field of investment casting, in particular to a preparation method of a high-dimensional-precision ceramic core and a casting forming method. The preparation method of the high-dimensional-precision ceramic core comprises the following steps: (a) designing a ceramic core structure and a wax shell structure for preparing the ceramic core structure according to the structure of a casting; (b) preparing a wax shell structure by adopting photosensitive resin in a 3D printing manner; (c) pouring slurry into the wax shell structure, and roasting to obtain a ceramic core; the slurry comprises silica sol, polyacrylamide and zircon powder, the mass ratio of the silica sol to the polyacrylamide is 100: (0.02-0.06), and the mass ratio of the zircon powder to the silica sol is (2.5-3.5): 1. The photosensitive resin is used for manufacturing the wax shell, so that the surface quality and the size precision of the manufactured ceramic core can be improved; moreover, a certain amount of polyacrylamide is added into the slurry for preparing the ceramic core, so that the production cycle of the ceramic core is remarkably shortened, and meanwhile, the raw material cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of investment casting, in particular to a method for preparing a high-dimensional precision ceramic core and a casting molding method. Background Art

[0002] Investment casting is a process for producing high-precision, high-surface-quality castings. Its principles can be traced back to the traditional lost-wax casting method of ancient my country. The modern investment casting process primarily involves wax pattern preparation, shell preparation, and melting and pouring. For castings with complex cavity structures, particularly those with casting piping, ceramic cores are used as the forming medium.

[0003] Currently, two main methods are used to prepare ceramic cores: hot injection molding, where slurry is injected into a mold cavity and cured to form the ceramic core; and reverse shelling, where a polystyrene wax shell is first created using 3D printing technology. The shelling slurry is then poured into the wax shell to form the ceramic core. The finished ceramic core undergoes rigorous quality inspection before being put into use.

[0004] However, existing ceramic core preparation technology has obvious limitations: the traditional mold preparation cycle is as long as 20 days. For small-batch products in scientific research, this process solution is not only too long but also less economical. When using the reverse shell process, due to the limitations of the precision of 3D printed polystyrene materials, the dimensional accuracy of the formed wax shell is difficult to guarantee. In addition, there is a difference in the thermal expansion coefficients of the ceramic core material and the shell material, which can easily lead to defects such as breakage or positional displacement of the ceramic core during the roasting process, ultimately affecting the dimensional accuracy requirements of the casting.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing a ceramic core with high dimensional precision and a casting molding method. The present invention can significantly shorten the preparation time of the ceramic core, and at the same time the prepared ceramic core has high dimensional precision and good surface finish.

[0007] In order to achieve the above-mentioned object of the present invention, the first aspect of the present invention provides a method for preparing a ceramic core with high dimensional precision, comprising the following steps:

[0008] (a) Designing a ceramic core structure and a wax shell structure for preparing the ceramic core structure according to the structure of the casting;

[0009] (b) preparing the wax shell structure by 3D printing using a photosensitive resin;

[0010] (c) pouring slurry into the wax shell structure and then firing to obtain a ceramic core;

[0011] The slurry includes silica sol, polyacrylamide and zircon powder. The mass ratio of the silica sol to the polyacrylamide is 100:(0.02-0.06), and the mass ratio of the zircon powder to the silica sol is (2.5-3.5):1.

[0012] In a specific embodiment of the present invention, the particle size of the zircon powder is 275-325 mesh.

[0013] In a specific embodiment of the present invention, the silica content of the silica sol is ≥30%.

[0014] In a specific embodiment of the present invention, the viscosity of the slurry at 23° C. measured according to ASTM D4212 is 10-20s.

[0015] In a specific embodiment of the present invention, the grouting slurry comprises:

[0016] (1) After pouring slurry into the wax shell structure, controlling the slurry, drying, and inserting a metal wire into the cavity of the wax shell structure;

[0017] (2) pouring slurry into the wax shell structure obtained in step (1), controlling the slurry, and drying;

[0018] (3) Repeat step (2) until the cavity of the wax shell structure is filled.

[0019] In a specific embodiment of the present invention, the grouting slurry is subjected to sanding after at least one slurry control. Furthermore, the sanding is white corundum sand with a mesh size of 80 to 100.

[0020] In a specific embodiment of the present invention, in step (1), after the slurry control, sand spreading treatment is performed.

[0021] In a specific embodiment of the present invention, the metal wire is an iron wire. Furthermore, the diameter of the iron wire is 0.5 to 1.5 mm.

[0022] In a specific embodiment of the present invention, in the grouting slurry, the drying is ventilation drying, and the drying time for a single time is 3 to 4 hours.

[0023] In a specific embodiment of the present invention, the calcination comprises: keeping the temperature at 775-825° C. for 2-3 hours, and then naturally cooling to room temperature.

[0024] In a specific embodiment of the present invention, the thickness of the wax shell structure is 0.8 to 1.5 mm.

[0025] A second aspect of the present invention provides a casting molding method, comprising the following steps:

[0026] The ceramic core is prepared by the method for preparing a ceramic core with high dimensional accuracy provided by the first aspect of the present invention; the ceramic core is installed and fixed to a wax mold, a mold shell is prepared, and pouring is performed to obtain the casting.

[0027] In a specific embodiment of the present invention, a wax layer is provided on one end surface of the ceramic core, and further, the wax layer has a thickness of 0.2 to 0.4 mm.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) In the preparation of the ceramic core of the present invention, a photosensitive resin is used to make a wax shell, which can improve the surface quality and dimensional accuracy of the ceramic core prepared using the wax shell; and, in addition, a certain amount of polyacrylamide is added to the slurry used to prepare the ceramic core of the present invention, which significantly shortens the production cycle of the ceramic core and reduces the raw material cost;

[0030] (2) The expansion coefficient of the ceramic core material of the present invention is close to that of the shell material. Combined with the design of the free end of the ceramic core, the possibility of the ceramic core breaking during the firing process can be reduced, and the dimensional accuracy of the casting can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 The wax shell structure provided in Example 1 of the present invention;

[0033] Figure 2 The ceramic core prepared in Example 1 of the present invention;

[0034] Figure 3 The ceramic core prepared in Example 2 of the present invention;

[0035] Figure 4 This is the ceramic core prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0037] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] A first aspect of the present invention provides a method for preparing a high-dimensional precision ceramic core, comprising the following steps:

[0040] (a) Designing a ceramic core structure and a wax shell structure for preparing the ceramic core structure according to the structure of the casting;

[0041] (b) using photosensitive resin to prepare the wax shell structure through 3D printing;

[0042] (c) pouring slurry into the wax shell structure and then firing it to obtain a ceramic core;

[0043] The slurry includes silica sol, polyacrylamide and zircon powder. The mass ratio of silica sol to polyacrylamide is 100:(0.02~0.06), and the mass ratio of zircon powder to silica sol is (2.5~3.5):1.

[0044] In the preparation of the ceramic core of the present invention, a photosensitive resin is used to make a wax shell, which can improve the surface quality and dimensional accuracy of the ceramic core made using the wax shell; and, in the present invention, a certain amount of polyacrylamide is added to the slurry used to prepare the ceramic core, which not only meets the performance requirements for the ceramic core but also significantly shortens the production cycle of the ceramic core while reducing the raw material cost.

[0045] For example, in various embodiments, the mass ratio of silica sol to polyacrylamide in the slurry of the present invention can be 100:0.02, 100:0.0225, 100:0.03, 100:0.04, 100:0.05, 100:0.06, or any combination thereof. Adjusting the silica sol to polyacrylamide ratio in the slurry within this range not only accelerates the drying of the ceramic core and shortens the overall production cycle, but also maintains or even improves the rheological and sintering properties of the slurry, thereby improving the strength and stability of the ceramic core and enhancing the dimensional accuracy of the casting.

[0046] For example, in different embodiments, in the slurry of the present invention, the mass ratio of zircon powder to silica sol can be 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, or a range consisting of any two thereof.

[0047] In specific embodiments of the present invention, the slurry of the present invention may further include an optional wetting agent and an optional defoaming agent. For example, based on 10 kg of silica sol in the slurry, the amount of wetting agent used may be 16-20 mL, and the amount of defoaming agent used may be 12-16 mL. The present invention does not strictly limit the specific types of silica sol, wetting agent, and defoaming agent. It is understood that any silica sol, wetting agent, and defoaming agent that can be used to prepare the ceramic core can be used. For example, the wetting agent can be RS-6401, and the defoaming agent can be RS-6503. The types here are the ones we have been using. If necessary, relevant information will be supplemented.

[0048] In a specific embodiment of the present invention, the preparation of the slurry of the present invention includes: mixing polyacrylamide and water to prepare a polyacrylamide aqueous solution; adding the polyacrylamide aqueous solution to the silica sol, and then mixing it with zircon powder, and then adding optional wetting agents and defoaming agents, and stirring evenly.

[0049] In a specific embodiment of the present invention, the mass fraction of the polyacrylamide aqueous solution can be 0.1% to 0.2%.

[0050] The preparation method of the present invention is suitable for the rapid production needs of multiple varieties and small batches of castings with casting pipes. For example, the diameter of the casting pipe of the present invention is ≥φ7mm, for example, it can be φ8mm, φ10mm, φ12mm, φ15mm, φ18mm, φ20mm, or a range consisting of any two thereof; the length is ≤200mm, for example, it can be 100mm, 120mm, 150mm, 180mm, 200mm, or a range consisting of any two thereof. It is understood that the preparation method of the ceramic core of the present invention is suitable for the preparation of ceramic cores with a length of no more than 200mm for casting pipes, and there is no limit on the lower limit of the length of the casting pipe. In addition, in the preparation method of the present invention, there is no limit on the cross-sectional shape of the ceramic core, for example, it can include but is not limited to a circle, and it is also applicable to ceramic cores with special-shaped structures.

[0051] In practice, in step (a), the ceramic core structure and the wax shell structure used to prepare the ceramic core structure can be designed based on the structural requirements of the casting using conventional means, such as 3D software simulation. In step (b), the wax shell structure can be prepared using photosensitive resin through 3D printing using conventional means. For example, based on the wax shell structure in step (a), a 3D model of the wax shell structure can be designed using software such as CAD, and then printed using a photosensitive resin using a 3D printer and photocured to obtain the wax shell structure.

[0052] The photosensitive resin used in the present invention can be a conventional commercially available low-ash photosensitive resin that can be used for 3D printing (for example, it can be at least one of 6009-209DLP resin, Somos 19120 resin, Somos Element resin, and Formlabs Castable resin). The specific curing conditions can be conventionally adjusted according to the photosensitive resin used.

[0053] In a specific embodiment of the present invention, the particle size of the zircon powder is 275-325 mesh, for example, 275 mesh, 300 mesh, 325 mesh, etc.

[0054] In a specific embodiment of the present invention, the silicon dioxide content of the silica sol is ≥30%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35% or a range consisting of any two thereof.

[0055] In a specific embodiment of the present invention, the weight average molecular weight of the polyacrylamide is 2 million to 6 million, for example, it can be 2 million, 3 million, 4 million, 5 million, 6 million or any two thereof.

[0056] In a specific embodiment of the present invention, the polyacrylamide is nonionic polyacrylamide.

[0057] In a specific embodiment of the present invention, the viscosity of the slurry at 23°C is 10-20s, for example, 10s, 12s, 15s, 18s, 20s, or any combination thereof, as measured according to ASTM D4212. Specifically, the viscosity is measured using a #4 standard flow cup in accordance with ASTM D4212. This helps to achieve both improved slurry filling integrity and dimensional accuracy of the ceramic core.

[0058] In the preparation of the slurry, when the slurry viscosity is not within the above range, the amounts of silica sol and zircon powder are adjusted within the mass ratio range of the two so that the slurry viscosity meets the above requirements.

[0059] In a specific embodiment of the present invention, the pouring slurry comprises:

[0060] (1) After pouring slurry into the wax shell structure, controlling the slurry, drying, and inserting a metal wire into the cavity of the wax shell structure;

[0061] (2) pouring slurry into the wax shell structure obtained in step (1), controlling the slurry, and drying;

[0062] (3) Repeat step (2) until the cavity of the wax shell structure is filled.

[0063] During the grouting process of the present invention, the number of repetitions of step (3) is related to the diameter of the cavity inside the wax shell structure (i.e., the diameter of the ceramic core). As the diameter of the cavity increases, the number of repetitions increases to ensure that the cavity is filled.

[0064] In a specific embodiment of the present invention, the grouting slurry is sanded after at least one slurry control step. Furthermore, the sand used in the sanding step is 80-100 mesh white corundum sand. This sanding step further helps improve the surface roughness, mechanical strength, and high-temperature stability of the ceramic core.

[0065] In a specific embodiment of the present invention, in step (1), after slurry control, sand spreading treatment is performed.

[0066] In a specific embodiment of the present invention, the metal wire is an iron wire. Furthermore, the diameter of the iron wire is 0.5 to 1.5 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, or any combination thereof. The provision of the metal wire further ensures the strength of the ceramic core.

[0067] In actual operation, the diameter of the metal wire used can be adjusted according to the diameter of the ceramic core. Under the premise of ensuring the normal pouring of slurry, a metal wire with a larger diameter can be used as much as possible.

[0068] In a specific embodiment of the present invention, the metal wire passes through the cavity of the wax shell structure and extends to the outside of both ends of the cavity. Furthermore, the length of the metal wire extending to the outside of both ends of the cavity is ≥10 mm.

[0069] In a specific embodiment of the present invention, the grouting slurry is dried by ventilation, and the drying time for a single drying is 3 to 4 hours. By adjusting the composition of the slurry, the present invention significantly shortens the drying time and improves production efficiency while ensuring the strength and other properties of the ceramic core after forming.

[0070] In a specific embodiment of the present invention, the roasting comprises: holding at 775-825°C for 2-3 hours, followed by natural cooling to room temperature. For example, in different embodiments, the roasting temperature can be 775°C, 780°C, 790°C, 800°C, 810°C, 820°C, 825°C, or a range consisting of any two thereof, and the holding time can be 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, or a range consisting of any two thereof. In actual operation, the roasting is carried out by a warm-up furnace charging method, that is, the temperature of the roasting furnace is pre-heated to the holding temperature before the dried ceramic core is placed.

[0071] In a specific embodiment of the present invention, a plurality of exhaust holes are provided on the wax shell structure to facilitate exhaust and slurry control during slurry pouring and sand control after sand spreading.

[0072] In a specific embodiment of the present invention, the wax shell structure is provided with an injection hole. The injection hole can be provided at the end of the wax shell structure, and the diameter of the injection hole is greater than or equal to the diameter of the ceramic core structure.

[0073] In a specific embodiment of the present invention, the thickness of the wax shell structure is 0.8-1.5 mm, for example, it can be 0.8 mm, 1 mm, 1.2 mm, 1.5 mm or a range consisting of any two thereof.

[0074] A second aspect of the present invention provides a casting molding method, comprising the following steps:

[0075] The ceramic core is prepared by adopting the preparation method of the ceramic core with high dimensional accuracy provided by the first aspect of the present invention; the ceramic core and the wax mold are installed and fixed, a mold shell is prepared, and pouring is performed to obtain a casting.

[0076] In a specific embodiment of the present invention, a wax layer is provided on one end surface of the ceramic core, and the thickness of the wax layer is 0.2 to 0.4 mm.

[0077] In practice, the ceramic core consists of a fixed end and a free end, with the free end coated with a wax layer. The ceramic core is then placed into a wax mold, which is equipped with at least two support and positioning protrusions. After positioning and bonding, the core is then subjected to conventional slurry pouring, sanding, dewaxing, and firing to form a shell with a cavity. The fixed end is encased in the shell, while the free end, due to the wax layer, is separated from the shell to prevent breakage due to differences in expansion coefficients between the core and the shell.

[0078] Example 1

[0079] This embodiment provides a method for preparing a ceramic core with high dimensional precision, comprising the following steps:

[0080] (1) Designing a ceramic core structure and a wax shell structure for preparing the ceramic core structure based on the structure of the casting, and preparing the wax shell structure by 3D printing using a photosensitive resin Somos Element; Figure 1 This is the wax shell structure produced by 3D printing in this embodiment.

[0081] (2) Add polyacrylamide (weight-average molecular weight of 6 million) to pure water to prepare an aqueous solution of polyacrylamide with a mass fraction of 0.15%. Take 10 kg of silica sol (silicon dioxide content of 33%), add 1.5 kg of the aqueous solution of polyacrylamide to it, and prepare a quick-drying silica sol. Take 30 kg of 275-325 mesh zircon powder and add it to the quick-drying silica sol. Stir thoroughly. The viscosity of the slurry at 23°C is 15 seconds as measured according to ASTM D4212. Then, add 18 mL of wetting agent (RS-6401) and 14 mL of defoaming agent (RS-6503), stir thoroughly and mix thoroughly to obtain a slurry.

[0082] (3) pouring slurry into the wax shell structure obtained in step (1), and after controlling the slurry, sprinkle 80-100 mesh white corundum sand, and ventilate and dry for 3 hours after controlling the sand; then inserting an iron wire with a diameter of φ1 mm into the cavity of the wax shell structure, and pouring slurry again, and after controlling the slurry, sprinkle 80-100 mesh white corundum sand, and ventilate and dry for 3 hours after controlling the sand; repeating the above process of pouring slurry, controlling the slurry, sprinkling sand, and controlling the sand and drying until the cavity is completely filled.

[0083] (4) The ceramic core obtained in step (3) is placed in an electric furnace, which is preheated to 800° C. and kept warm for 2 h. The ceramic core is then naturally cooled to room temperature with the furnace, and the surface of the ceramic core is polished with fine sandpaper to obtain a ceramic core. Figure 2 This is the ceramic core obtained in Example 1. The diameter of the ceramic core is φ15 mm and the length is 190 mm.

[0084] Example 2

[0085] This embodiment refers to the preparation method of Example 1, except that: the ceramic core structure and the wax shell structure of this embodiment are different.

[0086] The ceramic core prepared by the preparation method of reference embodiment 1 is as follows Figure 3 As shown, the diameter of the ceramic core is φ10 mm and the length is 120 mm.

[0087] Example 3

[0088] This embodiment refers to the preparation method of Example 1, except that: the ceramic core structure and the wax shell structure of this embodiment are different.

[0089] The ceramic core prepared by the preparation method of reference embodiment 1 is as follows Figure 4 As shown, the diameter of the ceramic core is 7 mm and the length is 140 mm.

[0090] Example 4

[0091] This example refers to the preparation method of Example 1, except that: in this example, the slurry in step (2) is different.

[0092] In the slurry of this embodiment, the amount of the aqueous solution of polyacrylamide used is 1.34 kg.

[0093] Example 5

[0094] This example refers to the preparation method of Example 1, except that: in this example, the slurry in step (2) is different.

[0095] In the slurry of this embodiment, the amount of the polyacrylamide aqueous solution used is 4 kg.

[0096] In this embodiment, the amount of the aqueous solution of polyacrylamide added is high, and the drying cycle and dimensional accuracy of the ceramic core are not affected. However, microcracks appear on the surface of the ceramic core, affecting subsequent use.

[0097] Example 6

[0098] This example refers to the preparation method of Example 1, except that: in this example, the slurry in step (2) is different.

[0099] In the slurry of this embodiment, the amount of the polyacrylamide aqueous solution used is 2 kg.

[0100] Comparative Example 1

[0101] Comparative Example 1 uses hot pressing to prepare a ceramic core with the same structure as Example 1, which specifically includes the following steps: mixing, slurrying, molding, and calcining; the specific method refers to the first embodiment in the Chinese patent application with publication number CN102603275A.

[0102] Comparative Example 2

[0103] Comparative Example 2 uses a mold to prepare a wax shell and grouting to prepare a ceramic core with the same structure as Example 1, specifically comprising the following steps:

[0104] ①Wax shell preparation: Use wax pressing machine and wax shell mold to make ceramic core wax shell;

[0105] ② Preparation of slurry: refer to step (2) of Example 1, except that no polyacrylamide is added, that is, the aqueous solution of polyacrylamide is replaced with pure water of equal mass;

[0106] ③ Grouting: refer to step (3) of Example 1;

[0107] ④ Calcination: Refer to step (4) of Example 1, except that the ceramic core obtained in step (3) is first placed in a dewaxing kettle for dewaxing to remove the wax shell; and then placed in an electric furnace for calcination.

[0108] Comparative Example 3

[0109] Comparative Example 3 refers to the preparation method of Example 1, except that:

[0110] In step (1), a polystyrene wax shell is prepared by 3D printing;

[0111] In step (2), the slurry is different; the preparation of the slurry of Comparative Example 3 refers to Example 1, except that no polyacrylamide is added, that is, the aqueous solution of polyacrylamide is replaced by pure water of equal mass.

[0112] Comparative Example 4

[0113] Comparative Example 4 refers to the preparation method of Example 1, except that:

[0114] In step (1), a polystyrene wax shell is prepared by 3D printing.

[0115] Comparative Example 5

[0116] Comparative Example 5 refers to the preparation method of Example 1, except that:

[0117] In step (2), the slurries are different; the slurry of Comparative Example 5 is the same as that of Comparative Example 3.

[0118] Experimental example

[0119] The preparation time, dimensional accuracy (measured with a caliper, with a dimensional tolerance range based on HB6103-2004) and surface quality (using a surface roughness comparison sample) of the ceramic cores of different embodiments and comparative examples were calculated and characterized. The results are shown in Table 1.

[0120] Table 1 Characterization results

[0121] serial number Preparation time Ceramic core dimensional accuracy Surface quality Example 1 4 days HB6103-CT5 ≤Ra3.2 Example 2 4 days HB6103-CT5 ≤Ra3.2 Example 3 4 days HB6103-CT5 ≤Ra3.2 Example 4 4 days HB6103-CT5 ≤Ra3.2 Example 5 4 days HB6103-CT5 Surface microcracks Example 6 4 days HB6103-CT5 ≤Ra3.2 Comparative Example 1 20 days HB6103-CT4 ≤Ra3.2 Comparative Example 2 20 days HB6103-CT5 ≤Ra3.2 Comparative Example 3 10 days HB6103-CT7 <![CDATA[ Ra 3.2~Ra6.3]]> Comparative Example 4 5 days HB6103-CT7 <![CDATA[ Ra 3.2~Ra6.3]]> Comparative Example 5 8 days HB6103-CT5 ≤Ra3.2

[0122] The above results show that, given the same core structure, the production cycle for the present invention's ceramic core is generally approximately 4 days, while the production cycle for ceramic cores prepared using hot pressing or mold-based wax shells is generally approximately 20 days. The use of a photosensitive resin in the wax shell improves the surface quality and dimensional accuracy of the ceramic core produced using this wax shell. Furthermore, the addition of a certain amount of polyacrylamide to the slurry used in the present invention significantly shortens the production cycle while reducing raw material costs.

[0123] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-dimensional precision ceramic core, characterized in that: The steps include: (a) Designing a ceramic core structure and a wax shell structure for preparing the ceramic core structure according to the structure of the casting; (b) preparing the wax shell structure by 3D printing using a photosensitive resin; (c) pouring slurry into the wax shell structure and then firing to obtain a ceramic core; The slurry includes silica sol, polyacrylamide and zircon powder. The mass ratio of the silica sol to the polyacrylamide is 100:(0.02-0.06), and the mass ratio of the zircon powder to the silica sol is (2.5-3.5):

1.

2. The preparation method according to claim 1, characterized in that The particle size of the zircon powder is 275-325 mesh; Preferably, the silica sol has a silicon dioxide content of ≥30%; Preferably, the weight average molecular weight of the polyacrylamide is 2 million to 6 million; Preferably, the viscosity of the slurry at 23° C. measured according to ASTM D4212 is 10 to 20 seconds.

3. The preparation method according to claim 1, characterized in that The grouting material comprises: (1) After pouring slurry into the wax shell structure, controlling the slurry, drying, and inserting a metal wire into the cavity of the wax shell structure; (2) pouring slurry into the wax shell structure obtained in step (1), controlling the slurry, and drying; (3) Repeat step (2) until the cavity of the wax shell structure is filled.

4. The preparation method according to claim 3, characterized in that In the grouting slurry, sanding is performed after at least one slurry control; Preferably, in the sand spreading, the sand material is 80-100 mesh white corundum sand; Preferably, in step (1), after the slurry is controlled, sanding treatment is performed.

5. The preparation method according to claim 3, characterized in that The metal wire is iron wire; Preferably, the diameter of the iron wire is 0.5-1.5 mm.

6. The preparation method according to claim 3, characterized in that In the pouring slurry, the drying is ventilation drying, and the drying time for a single time is 3 to 4 hours.

7. The preparation method according to claim 1, characterized in that The calcination comprises: keeping the temperature at 775-825° C. for 2-3 hours, and then naturally cooling the mixture to room temperature.

8. The preparation method according to claim 1, characterized in that The thickness of the wax shell structure is 0.8-1.5 mm.

9. A casting molding method, characterized in that: The ceramic core is prepared by the method for preparing a high-dimensional precision ceramic core according to any one of claims 1 to 8; the ceramic core is installed and fixed to a wax mold, a mold shell is prepared, and pouring is performed to obtain the casting.

10. The casting molding method according to claim 9, characterized in that: Providing a wax layer on one end surface of the ceramic core; Preferably, the thickness of the wax layer is 0.2 to 0.4 mm.

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