A spherical seed crystal, a method for preparing a spherical seed crystal, and a mold shell structure for preparing a single crystal blade

Abstract

The application provides a spherical seed crystal, a spherical seed crystal preparation method and a mold shell structure for preparing a single crystal blade, and relates to the technical field of single crystal blades. A preparation method of a spherical seed crystal comprises the following steps: S1. preparing a seed crystal string wax mold: a plurality of spherical seed crystal monomer wax molds are prepared according to the size of the spherical seed crystal and are combined into a seed crystal string wax mold; S2. preparing a mold shell: a bottom disc wax mold, a selector, the seed crystal string wax mold and a sprue are sequentially connected to form a group tree, and the mold shell is prepared; S3. installing a calibrated starting seed crystal in the mold shell, pulling the seed crystal at a constant speed in a vacuum furnace, obtaining a single crystal seed crystal rod generated by directional solidification, and after cooling, the shell is cleaned, the orientation is marked, cutting, polishing, and the spherical seed crystal is obtained. The spherical seed crystal improves the use efficiency of the seed crystal and greatly improves the universal adaptability of the seed crystal. The seed crystal is spherical, and there is no shape difference caused by cutting in a specific direction, so that the preparation of the wax mold and the mold shell is more unified and convenient.

Description

Technical Field

[0001] This invention relates to the field of single-crystal blade technology, and more specifically, to a spherical seed crystal, a method for preparing the spherical seed crystal, and a mold shell structure for preparing single-crystal blades. Background Technology

[0002] Single-crystal superalloy blades are one of the core components of aero-engines. They operate for extended periods in environments characterized by high temperature, high pressure, complex stress, and high-temperature exhaust erosion. Therefore, aero-engine blades have stringent material requirements, and nickel-based single-crystal superalloys are currently the most common high-temperature alloy blade materials.

[0003] Currently, the orientation of single-crystal blades is close to... <001> The direction is primary, which necessitates separate preparation. <001> Seed crystals, or those with the smallest possible orientation deviation, are crucial for optimal seed crystal production. However, in actual seed crystal production using the selective crystal method, at least 50% of the seed crystals fail to meet the required crystal orientation angles. The demand for seed crystals in single-crystal blade production is enormous, making the seed crystal yield rate particularly low. This not only causes significant cost issues but also impacts the production schedule of other products such as single-crystal blades.

[0004] Existing seed crystals are generally cylindrical or square. If the angle deviates during seed crystal production... <001> Significant deviations in seed crystal orientation generally result in their rejection, with out-of-tolerance orientation being the primary reason for unusable seed crystals. To precisely control seed crystal orientation and utilize those with significant deviations, CN113084088A mentions directional cutting methods, but these still have limitations: they are inconvenient to use when the seed crystal angle deviation is too large. When preparing seed crystals using the selection method or seed crystal method, the generation of impurities cannot be completely avoided; therefore, test pieces with significant orientation deviations are frequently encountered. Summary of the Invention

[0005] The purpose of this invention is to provide a spherical seed crystal and a method for preparing spherical seed crystals. The spherical seed crystal cleverly solves the problem of conventional seed crystals being scrapped or inconvenient to use when the orientation deviates significantly by utilizing its shape characteristics, thereby improving the efficiency of seed crystal use. Theoretically, the utilization rate can reach 100%, and it also greatly improves the universality and adaptability of seed crystals: the seed crystal will not produce shape differences due to cutting in a specific direction, thus making the preparation of wax molds and mold shells more uniform and convenient.

[0006] The present invention also aims to provide a mold shell structure for preparing single-crystal blades, which can mass-produce single-crystal blades and can also produce single-crystal blades with different specific orientations.

[0007] This invention is achieved through the following technical solution: A method for preparing spherical seed crystals includes the following steps: S1. Preparation of seed crystal string wax mold: Prepare multiple spherical seed crystal individual wax molds according to the size of the spherical seed crystal and combine them into a seed crystal string wax mold; S2. Preparation of the mold shell: The base wax mold, crystal selector, seed crystal string wax mold and sprue are connected in sequence to form a tree and the mold shell is made. S3. Install the calibrated initial seed crystal inside the mold shell, and pull the seed crystal at a constant speed in a vacuum furnace to obtain a single crystal seed crystal rod produced by directional solidification. After cooling, the seed crystal rod is cleaned, cut, etched, crystal orientation detected, marked with orientation, cut again, and polished to obtain a spherical seed crystal.

[0008] Excessive crystal orientation is the main reason why seed crystals are unusable. The inventors proposed using a spherical seed crystal, which only requires marking the spherical seed crystal. <001> With proper orientation, it can be used, completely solving the problem of seed crystals being unusable or requiring directional cutting due to excessive angular deviation. Furthermore, spherical seed crystals have extremely high applicability and are not limited to... <001> Direction, marking <011> or <111> It can also be used as a seed crystal with a specific orientation.

[0009] Furthermore, the diameter of the seed crystal string wax mold in S1 is 10-30mm.

[0010] Furthermore, the vacuum furnace temperature in S3 is 1400-1600℃, and the pulling speed is 1-6mm / min.

[0011] A spherical seed crystal is prepared using the above-described method for preparing spherical seed crystals.

[0012] A mold shell structure for preparing single-crystal blades includes a water-cooling plate, an annular runner, a pouring cup, and a spherical seed crystal as described in claim 4. The water-cooling plate has a seed crystal mold shell in the middle, and the spherical seed crystal is located inside the seed crystal mold shell. The outer wall of the pouring cup has a plurality of first runners evenly distributed in an annular pattern, each of the first runners being connected to the annular runner. The bottom of the annular runner has a plurality of blade mold shells evenly distributed in an annular pattern, and the bottom of each blade mold shell has a second runner connected to the seed crystal mold shell.

[0013] When using, align the markings on the spherical seed crystal with the vertical direction. One spherical seed crystal corresponds to one module (multiple blade mold shells).

[0014] Furthermore, the number of blade mold shells is 4-10.

[0015] Furthermore, the blade mold shell is perpendicular to the water cooling plate, and the bottom of the blade mold shell is connected to the water cooling plate via a support rod.

[0016] Furthermore, a sealing mold shell is provided at the bottom of the seed crystal mold shell, located below the spherical seed crystal, with a height of 5-30mm. This sealing serves two purposes: firstly, it prevents leakage after the molten metal is poured into the mold shell; secondly, within this height range, it ensures good local melting of the seed crystal, making it easier to replicate the seed crystal orientation.

[0017] Furthermore, the sealing mold shell is made of a mixture of slurry and corundum sand. The slurry is a mixture of silica sol and fine corundum sand, with a mass ratio of silica sol to fine corundum sand of 1:3, and a mass ratio of slurry to corundum sand of 1:2-5. Silica sol, fine corundum sand, and corundum sand ensure the sealing effect and also have certain thermal conductivity, allowing for better local melting of the seed crystal.

[0018] The technical solution of the present invention has at least the following advantages and beneficial effects: This invention employs spherical seed crystals, which, without improving the "pass rate" of the crystal orientation angle in the original seed crystal preparation, "turns waste into treasure." Similar to the aforementioned reference patent on directional cutting, this invention improves the utilization rate of seed crystals with large orientation deviations. Unlike the latter, this application does not involve a directional cutting process, and the utilization rate of seed crystals with large orientation deviations is almost 100%. Since the seed crystal sizes produced by directional cutting vary greatly, this application leverages its advantages and avoids its disadvantages by using seed crystals of identical specifications. This allows for uniformity in mold specifications during production, and also standardization in processes such as tree assembly and shell making, facilitating management. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the mold shell structure in the spherical seed crystal preparation method provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the single crystal seed rod cutting process provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the spherical seed crystal cutting process provided in Embodiment 1 of the present invention; Figure 4 The single crystal seed rod marker provided in Embodiment 1 of the present invention <001> A diagram illustrating the direction; Figure 5 The spherical seed crystal marker provided in Embodiment 1 of the present invention <001> A diagram illustrating the direction; Figure 6 This is a schematic diagram of the mold shell structure for preparing single-crystal blades provided in Embodiment 4 of the present invention; Figure 7 Provided for Embodiment 4 of the present invention Figure 6 The front view.

[0020] Icons: 1-Base, 2-Selector, 3-Spherical seed crystal, 4-Gating system; 101-Water cooling plate, 102-Annular runner, 103-Pour cup, 104-Seed crystal mold shell, 105-First runner, 106-Blade mold shell, 107-Second runner, 108-Support rod. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0022] Example 1 Reference Figures 1-5 This embodiment provides a method for preparing spherical seed crystals, including the following steps: S1. Preparation of seed crystal string wax mold: Prepare multiple spherical seed crystal 3 individual wax molds according to the size of spherical seed crystal 3 and combine them into a seed crystal string wax mold. The diameter of the seed crystal string wax mold is 10mm. S2. Preparation of the mold shell: The base plate 1 wax model, crystal selector 2, seed crystal string wax model and sprue 4 are connected in sequence to form a tree and the mold shell is made. S3. Install the calibrated initial seed crystal inside the mold shell, and pull the seed crystal at a constant speed in a vacuum furnace. The vacuum furnace temperature is 1500℃ and the pulling speed is 5mm / min to obtain a single crystal seed crystal rod produced by directional solidification. After cooling, clean the shell and cut it according to the cutting lines of the top sprue rod and the bottom spiral section of the seed crystal. Grind and polish the cut surface, and after etching, use a single crystal orientation instrument to measure the crystal orientation of the single crystal test rod and record the γ, δ, and K values, which represent the crystal orientation of all spherical seed crystals in the entire single crystal test rod.

[0023] Calculated using γ, δ, and K values <001> The three-dimensional vector direction of orientation, <001> The spatial vector direction is: , , The results were then recorded onto each spherical seed crystal 3 using a dedicated recorder. Each spherical seed crystal 3 was cut open from the joint using wire cutting, and the surface of each seed crystal was polished smooth while retaining the marking marks, thus obtaining the spherical seed crystal 3.

[0024] Example 2 This embodiment provides a method for preparing spherical seed crystals, including the following steps: S1. Preparation of seed crystal string wax mold: Prepare multiple spherical seed crystal 3 individual wax molds according to the size of spherical seed crystal 3 and combine them into a seed crystal string wax mold. The diameter of the seed crystal string wax mold is 20mm. S2. Preparation of the mold shell: The base plate 1 wax model, crystal selector 2, seed crystal string wax model and sprue 4 are connected in sequence to form a tree and the mold shell is made. S3. Install the calibrated initial seed crystal in the mold shell, and pull the seed crystal at a constant speed in a vacuum furnace. The vacuum furnace temperature is 1600℃ and the pulling speed is 4mm / min to obtain a single crystal seed crystal rod produced by directional solidification. After cooling, the shell is cleaned, and after cutting, etching, crystal orientation detection, calibration, cutting, and polishing, a spherical seed crystal 3 is obtained.

[0025] Example 3 This embodiment provides a method for preparing spherical seed crystals, including the following steps: S1. Preparation of seed crystal string wax mold: Prepare multiple spherical seed crystal 3 individual wax molds according to the size of spherical seed crystal 3 and combine them into a seed crystal string wax mold. The diameter of the seed crystal string wax mold is 30mm. S2. Preparation of the mold shell: The base plate 1 wax model, crystal selector 2, seed crystal string wax model and sprue 4 are connected in sequence to form a tree and the mold shell is made. S3. Install the calibrated initial seed crystal in the mold shell, and pull the seed crystal at a constant speed in a vacuum furnace. The vacuum furnace temperature is 1400℃ and the pulling speed is 6mm / min to obtain a single crystal seed crystal rod produced by directional solidification. After cooling, the shell is cleaned, and after cutting, etching, crystal orientation detection, calibration, cutting, and polishing, a spherical seed crystal 3 is obtained.

[0026] Example 4 Reference Figures 6-7 This embodiment provides a mold shell structure for preparing single crystal blades, including a water-cooling plate 101, an annular runner 102, a pouring cup 103, and a spherical seed crystal as described in claim 4. The water-cooling plate 101 has a seed crystal mold shell 104 in the middle, and the spherical seed crystal is located inside the seed crystal mold shell 104. The outer wall of the pouring cup 103 has a plurality of first runners 105 evenly distributed in an annular pattern. Each first runner 105 is connected to the annular runner 102. The bottom of the annular runner 102 has a plurality of blade mold shells 106 evenly distributed in an annular pattern. The bottom of each blade mold shell 106 has a second runner 107, and the second runner 107 is connected to the seed crystal mold shell 104.

[0027] In use, the markings on the spherical seed crystal are aligned with the vertical direction. One spherical seed crystal corresponds to one module (multiple blade mold shells 106). Furthermore, the number of blade mold shells 106 is 4-10.

[0028] In this embodiment, the blade mold shell 106 is perpendicular to the water cooling plate 101, and the bottom of the blade mold shell 106 is connected to the water cooling plate 101 through a support rod 108.

[0029] In this embodiment, a sealing mold shell is provided at the bottom of the seed crystal mold shell 104. The sealing mold shell is located below the spherical seed crystal, and the height of the sealing mold shell is 5-30mm. The sealing can prevent leakage after the molten metal is poured into the mold shell, and within this height range, it can ensure good local melting of the seed crystal, making it easier to replicate the seed crystal orientation.

[0030] In this embodiment, the sealing mold shell is made of a mixture of slurry and corundum sand. The slurry is a mixture of silica sol and fine corundum sand, with a mass ratio of silica sol to fine corundum sand of 1:3, and a mass ratio of slurry to corundum sand of 1:2-5. Silica sol, fine corundum sand, and corundum sand ensure the sealing effect and also have certain thermal conductivity, allowing for better local melting of the seed crystal.

[0031] In practical use, the following steps are included: preparing the label. <001> The oriented spherical seed crystal is placed inside the seed crystal mold shell 104, with the marking direction of the spherical seed crystal aligned with the vertical direction. The bottom of the spherical seed crystal is sealed with slurry and corundum sand, and the single crystal blade can be obtained after casting.

[0032] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing spherical seed crystals, characterized in that, Includes the following steps: S1. Preparation of seed crystal string wax mold: Prepare multiple spherical seed crystal individual wax molds according to the size of the spherical seed crystal and combine them into a seed crystal string wax mold; S2. Preparation of the mold shell: The base wax mold, crystal selector, seed crystal string wax mold and sprue are connected in sequence to form a tree and the mold shell is made. S3. Install the calibrated starting seed crystal inside the mold shell, and pull the seed crystal at a constant speed in a vacuum furnace to obtain a single crystal seed crystal rod produced by directional solidification. After cooling, clean the shell, mark the orientation, cut, and polish to obtain a spherical seed crystal.

2. The method for preparing spherical seed crystals according to claim 1, characterized in that, The diameter of the seed crystal string wax mold in S1 is 10-30mm.

3. The method for preparing spherical seed crystals according to claim 1, characterized in that, The vacuum furnace temperature in S3 is 1400-1600℃, and the pulling speed is 1-6mm / min.

4. A spherical seed crystal, characterized in that, It is prepared by the method for preparing spherical seed crystals according to any one of claims 1-3.

5. A mold shell structure for preparing single-crystal blades, characterized in that, The device includes a water-cooling plate, an annular runner, a pouring cup, and a spherical seed crystal as described in claim 4. The water-cooling plate has a seed crystal mold shell in the middle, and the spherical seed crystal is located inside the seed crystal mold shell. The outer wall of the pouring cup has a plurality of first runners evenly distributed in an annular pattern, each of which is connected to the annular runner. The bottom of the annular runner has a plurality of blade mold shells evenly distributed in an annular pattern, and the bottom of each blade mold shell has a second runner connected to the seed crystal mold shell.

6. The mold shell structure for preparing single-crystal blades according to claim 5, characterized in that, The number of blade mold shells is 4-10.

7. The mold shell structure for preparing single-crystal blades according to claim 5, characterized in that, The blade mold shell is perpendicular to the water cooling plate, and the bottom of the blade mold shell is connected to the water cooling plate via a support rod.

8. The mold shell structure for preparing single-crystal blades according to claim 5, characterized in that, The bottom of the seed crystal mold shell is provided with a sealing mold shell, which is located below the spherical seed crystal, and the height of the sealing mold shell is 5-30mm.

9. The mold shell structure for preparing single-crystal blades according to claim 8, characterized in that, The sealing mold shell is made of a mixture of slurry and corundum sand. The slurry is a mixture of silica sol and fine corundum sand, with a mass ratio of silica sol to fine corundum sand of 1:3 and a mass ratio of slurry to corundum sand of 1:2-5.

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