Control method for growing single crystal blade by using secondary dendritic crystal
By employing secondary dendrite seed crystals and segmented crystal pulling techniques, the problem of low success rate of single crystal blades caused by the large spacing of primary dendrites in existing technologies has been solved, achieving high success rate and high integrity in the preparation of single crystal blades.
Patent Information
- Application Number
- CN202512047583.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-02-17
AI Technical Summary
Existing technologies make it difficult to prepare single-crystal blades with small dendrite spacing, resulting in a low success rate of seed crystal growth of single-crystal blades, especially in water-cooling methods.
Secondary dendrites are used as the starting segment of the seed crystal. By controlling the direction and assembly process of the secondary orientation seed crystal, a secondary dendrite seed crystal mold shell is prepared. Combined with the segmented crystal pulling technology of high-temperature alloy liquid, the directional solidification of single crystal blades is realized.
It improves the success rate of seed crystal growth of single crystal blades, ensures the integrity and dimensional accuracy of single crystals, and reduces the generation of crystallization defects.
Smart Images
Figure CN121535137A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of precision casting of high-temperature alloy, and particularly relates to a control method for single crystal blade growth by secondary dendrite. BACKGROUND
[0002] Single crystal high-temperature alloy blade basically eliminates all grain boundaries and has excellent high-temperature performance. Currently, single crystal blade is mainly prepared by selection crystal method and seed crystal method. The selection crystal method can select single crystal blade through competitive growth, and the seed crystal method can realize orientation control of the blade while growing the single crystal blade. The seed crystal method for preparing single crystal blade has a certain seed crystal failure rate. Research shows that selecting seed crystal with smaller primary dendrite spacing can improve the success rate of seed crystal growth of single crystal blade. However, the primary dendrite spacing is mainly related to the temperature gradient and the crystal pulling speed of the blade. The water cooling method (HRS) is limited by equipment, and it is difficult to reduce the primary dendrite spacing, so it is difficult to prepare a blade with smaller primary dendrite spacing. SUMMARY
[0003] In order to solve the above technical problems, the purpose of the present application is to provide a control method for growing single crystal blade by secondary dendrite. The present application grows single crystal blade by using secondary dendrite as the starting section of the seed crystal, and prepares the seed crystal of secondary dendrite. The seed crystal is used to grow single crystal test bars, which effectively improves the success rate of seed crystal growth of single crystal test bars.
[0004] The technical scheme for solving the above technical problems of the present application is as follows: The purpose of the present application is to provide a preparation method of single crystal blade, which comprises the following steps: (1) selecting a
[001] oriented single crystal test bar, measuring and marking the 0° direction of the primary orientation and the secondary orientation of the single crystal test bar by Laue method, and cutting the single crystal test bar by wire cutting to obtain a secondary orientation seed crystal; The secondary orientation seed crystal is a cuboid, wherein the length direction of the cuboid is
[100] , the normal direction of two top surfaces is
[100] , and the normal direction of two side surfaces is
[001] and
[010] respectively; The secondary orientation seed crystal is a seed crystal with a deviation angle of
[100] within 5° and a secondary dendrite as the main direction; (2) pressing a seed crystal mold: pressing the secondary orientation seed crystal to obtain a seed crystal mold; pressing a plurality of wax molds, combining and connecting the wax molds with the seed crystal mold to obtain a wax mold module; (3) preparation of the mold module shell: coating, high-pressure dewaxing and high-temperature calcination are sequentially performed on the wax mold module to obtain a mold module shell; (4) Melting and investment casting: pouring the high-temperature alloy liquid of melting into a mold shell, after standing, using a segmented crystal pulling method to pull the crystal, realizing directional solidification of the single crystal blade, then cooling the mold shell and removing the shell, and finally cutting the pouring gate, removing the core, alkali cooking, heat treatment, corrosion inspection of the single crystal integrity to obtain the single crystal blade.
[0005] The beneficial effects of the present application are: the present application prepares secondary dendritic seeds, and the single crystal blade is grown by using the secondary dendritic seed as the starting section, the secondary dendritic seed of the single crystal blade is generally more fine than the primary dendritic seed, and the single crystal integrity of the secondary dendritic seed is better than that of the primary dendritic seed, thereby effectively improving the success rate of the seed crystal growth single crystal test rod.
[0006] Based on the above technical solution, the present application can be further improved as follows.
[0007] Further, the plurality of wax molds in step (2) includes a column tube, a pouring cup, a support gate upper disc, a test rod, and a circular bottom disc. The lower end of the secondary oriented seed crystal is inserted into a pad. The long side of the seed crystal is parallel to the side of the pad, the upper end of the seed crystal is inserted into an amplifier, the pad is uniformly bonded to the lower disc, the test rod is bonded to the middle of the seed crystal amplifier in the vertical direction, and the test rod is parallel to the
[100] direction of the secondary oriented seed crystal. The upper end of the test rod is bonded to the upper disc, the pouring cup is placed in the middle of the upper disc, the column tube is inserted into the middle of the pouring cup, and the support rod is connected between the pouring cup and the upper disc. There should be no defects such as welding seams and sharp corner burrs of the wax at the connection.
[0008] Further, the coating slurry in step (3) includes silica sol, white corundum powder, and a mineralizer.
[0009] Further, the mass ratio of the silica sol to the white corundum powder is 1:3-4, and the mass ratio of the mineralizer to the coating slurry is 2%-4%:1.
[0010] Further, the coated mold group in step (3) includes 5-7 layers of shell molds, and the total thickness is 3-10 mm.
[0011] The beneficial effects of the above further scheme are: to withstand the strength of the subsequent high-temperature alloy liquid.
[0012] Further, 80-120 mesh white corundum powder needs to be scattered on each layer of the shell mold.
[0013] Further, the pressure of the high-pressure dewaxing in step (3) is 0.3-1 MPa, and the dewaxing is carried out in a dewaxing kettle with a temperature of 100-200 DEG C.
[0014] The beneficial effects of the above further scheme are: to eliminate the residual wax material and ensure the quality of the casting.
[0015] Further, the high-temperature roasting in step (3) is at a temperature of 800-1200°C for 3-8 hours.
[0016] Further, the high-temperature alloy liquid in step (4) is at a temperature of 1500-1600°C, and the standing time is 5-20 minutes; the crystal pulling mode when moving downward is segmented crystal pulling.
[0017] The beneficial effect of the above further scheme is: high dimensional accuracy, good single crystal integrity.
[0018] Further, the segmented crystal pulling speed in step (4) is 2-10 mm / min.
[0019] Further, the shell removal in step (4) is: covering the mold shell with thermal insulation cotton, and naturally cooling for 6 hours before shell removal.
[0020] The beneficial effect of the above further scheme is: realizing uniform and slow cooling, and the thermal insulation cotton sleeve forms an effective heat insulation layer to avoid crystallization defects caused by local supercooling.
[0021] Further, the thickness of the thermal insulation cotton sleeve is 20-40 mm. BRIEF DESCRIPTION OF DRAWINGS
[0022] Figure 1 for the
[001] oriented single crystal test bar of embodiment 1 of the present application; Figure 2 for the secondary oriented seed crystal of embodiment 1 of the present application; Figure 3 for the seed crystal mold of embodiment 1 of the present application; Figure 4 for the mold shell schematic diagram of the mold group of embodiment 1 of the present application.
[0023] In the drawings, the components represented by each number are listed as follows: 1, center column tube; 2, sprue cup; 3, support gate; 4, upper disc; 5, test bar; 6, amplifier; 7, seed crystal; 8, cushion block; 9, circular base plate. DETAILED DESCRIPTION
[0024] The principles and features of the present application are described below, and the examples are only used to explain the present application, and are not used to limit the scope of the present application.
[0025] Embodiment 1: Preparation of single crystal blade (1) Select a
[001] oriented single crystal test bar, such as Figure 1The single crystal test rod is shown, and the single crystal integrity is checked. The single crystal test rod is measured by Laue method for one and two orientations. The single crystal test rod is oriented to 0° for one orientation. The test rod is rotated around the axis of the single crystal test rod for one orientation. The single crystal test rod is oriented to 0° for two orientations. The 0° direction of the one and two orientations is marked. The seed crystal is prepared by wire cutting. Figure 2 As shown, the two top surface directions of the cuboid long strip are
[100] directions, and the two side surfaces are
[001] directions and
[010] directions, respectively. The cut seed crystal is cleaned, and the surface of the seed crystal is cleaned with alcohol. After cleaning, the seed crystal is surface treated. After treatment, the deviation angle of the seed crystal in
[100] is measured by Laue crystal orientation measuring instrument again. The deviation angle is within 5°. The single crystal integrity is good. The orientation angle of the two orientation seed crystal meets the requirements; (2) Seed crystal pressing: Place the prepared two orientation seed crystal in a special mold for pressing. The center lines of the upper and lower end surfaces of the two orientation seed crystal and the pad and amplifier axis are kept on the same center line during the pressing process. The lower end of the seed crystal 7 is inserted into the pad 8. The long side surface of the seed crystal is parallel to the side surface of the pad. The upper end of the seed crystal is inserted into the amplifier 6 to obtain a seed crystal pad. As shown in Figure 3 ; (3) Mold assembly: The pad 8 is uniformly bonded to the lower disc 9. The test rod 5 is bonded in the middle of the seed crystal amplifier 6 along the vertical direction. The
[100] direction of the test rod 5 is parallel to the
[100] direction of the two orientation seed crystal. The upper end of the test rod 5 is bonded to the upper disc 4. The pouring cup 2 is placed in the middle of the upper disc 4. The middle column pipe 1 is inserted into the pouring cup 2. The support rod 3 is connected between the pouring cup 2 and the upper disc 4. There should be no defects such as wax weld and sharp burr at the connection, as shown in Figure 4 ; (4) Preparation of mold shell: The silica sol, white corundum powder and mineralizer are prepared into a coating slurry, which is coated on the surface of the wax mold module. The mass ratio of silica sol and white corundum powder is 1:3-4. The mineralizer accounts for 2%-4% of the total mass of the coating slurry. After the slurry is coated, 120-200 mesh white corundum powder is sprinkled. The shell type is repeated for 5-7 layers, and the thickness is 3-10 mm. The mold module coated with the slurry is placed in a dewaxing kettle with a pressure of 0.3-1 MPa and a temperature of 100-200°C for dewaxing. The dewaxed mold module is placed in a calcination furnace for calcination at a temperature of 800-1200°C for 3-8 hours to obtain a mold shell. (5) Shell investment casting: using a vacuum directional solidification furnace for pouring. The bottom surface of the mold shell is flat and clean, and the mold shell is placed on the crystallizer. After aligning the four sides, the mold shell is rotated to make the bottom of the mold shell tightly adhere to the crystallizer, the furnace door is closed, vacuum is extracted, and the mold shell is sent into the heater. The shell is heated to 1500-1580 DEG C, and kept for 10-30 min. Then, high-temperature alloy liquid is poured at 1500-1600 DEG C, and after pouring, the mold shell is kept for 5-20 min, and the crystal is pulled out in a segmented manner, with a pulling speed of 2-10 mm / min. When the upper surface of the upper disc of the mold shell moves out of the baffle, it is continuously moved downward at a speed of 3 mm / min for 2 min, and then quickly lowered to the bottom. After the shell is lowered to the bottom, the cast shell is taken out according to the operation procedure, and the mold shell is covered with a heat preservation cotton cover with a thickness of 20-40 mm. After the mold shell is naturally cooled for 6 h, the shell is removed. After cutting the runner, alkali boiling and heat treatment, the single crystal blade sample prepared in Example 1 is corroded by mixing 30% hydrochloric acid and 30% hydrogen peroxide in a volume ratio of 4:1, and the sample has no impurity crystal. It is shown that the single crystal has good integrity.
[0026] The single crystal blade sample is cut and detected using a special tool, the orientation of the sample is measured by referring to HB 6742 (determination of crystal orientation of single crystal blade X-ray back reflection Laue photography Laue method), the orientation angle of the sample deviates from the theoretical value within 5 DEG, and it is shown that the single crystal sample is successfully grown by using the secondary dendrite seed crystal. The service direction of the finally prepared single crystal blade of the application is consistent with the secondary orientation of the seed crystal.
[0027] A group of test rods are prepared by using the secondary dendrite and the primary dendrite by using the preparation method of the application, 16 test rods prepared by using the secondary dendrite seed crystal have no impurity crystal, and 2 of the 16 test rods prepared by using the primary dendrite seed crystal are scrapped. It can be seen that the single crystal integrity of the seed crystal prepared by the application is well maintained.
[0028] In the traditional seed crystal growth of single crystal blades, the service direction of the blade is consistent with the primary orientation of the seed crystal, and the prepared seed crystal is generally a primary dendrite seed crystal, and the primary orientation direction is generally parallel to the axis direction of the test rod (it is assumed that the axis direction of the test rod is consistent with the primary orientation). The Z axis of the prepared seed crystal is parallel to the axis of the test rod. In the application, the seed crystal is a secondary dendrite seed crystal, and the orientation of the seed crystal is perpendicular to the axis direction of the single crystal test rod. Through the application, the seed crystal preparation process is widened. When the primary orientation of the single crystal test rod deviates greatly and the secondary orientation angle is small, the secondary dendrite can be used to prepare the seed crystal by using the method of the application.
[0029] Although the embodiments of the application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be understood as limiting the application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the application.
Claims
1. A method of controlling the growth of a single crystal blade from a secondary dendrite, characterized by, It comprises the following steps: (1) selecting a single crystal test rod with [001] orientation, measuring and marking the 0° direction of the primary orientation and secondary orientation of the single crystal test rod by Laue method, and cutting the single crystal test rod by wire cutting to obtain a secondary orientation seed crystal; The secondary orientation seed crystal is a cuboid, wherein the length direction of the cuboid is [100], the normal direction of two top surfaces is [100], and the normal direction of two side surfaces is [001] and [010] respectively; The secondary orientation seed crystal is a seed crystal with a deviation angle of [100] within 5° and a primary direction of secondary dendrite; (2) pressing the secondary orientation seed crystal to obtain a seed crystal mold; pressing a plurality of wax molds, combining and connecting the wax molds and the seed crystal mold to obtain a wax mold module; (3) coating, high-pressure dewaxing, and high-temperature firing the wax mold module in sequence to obtain a mold shell module; (4) pouring a molten high-temperature alloy liquid into the mold shell, standing, using a segmented crystal pulling method to pull the crystal, realizing directional solidification of the single crystal blade, then cooling the mold shell and removing the shell, finally cutting the pouring gate, removing the core, alkali boiling, heat treatment, and corrosion inspection to obtain a single crystal blade.
2. A method of controlling the growth of a single crystal blade from a secondary dendrite according to claim 1, wherein The slurry of the coating in step (3) comprises silica sol, white corundum powder, and a mineralizer.
3. A method of controlling the growth of a single crystal blade from a secondary dendrite according to claim 2, wherein The mass ratio of the silica sol to the white corundum powder is 1:3-4; the mass ratio of the mineralizer to the coating slurry is 2%-4%:
1.
4. A method of controlling the growth of a single crystal blade from a secondary dendrite according to claim 3, wherein In step (3), the coated mold module comprises 5-7 layers of shell type with a total thickness of 3-10 mm.
5. The method of claim 1, wherein the method is characterized by: In step (3), the high-pressure dewaxing is performed at a pressure of 0.3-1 MPa and a temperature of 100-200°C in a dewaxing kettle.
6. The method of claim 1, wherein the method is characterized by: In step (3), the high-temperature firing is performed at a temperature of 800-1200°C for 3-8 h.
7. The method of claim 1, wherein the method is characterized by: In step (4), the temperature of the high-temperature alloy liquid is 1500-1600°C, and the standing time is 5-20 min.
8. The method of claim 1, wherein the method is characterized by: In step (4), the pulling speed of the segmented crystal pulling is 2-10 mm / min.
9. A method of controlling the growth of a single crystal blade from a secondary dendrite according to any one of claims 1 to 8, characterized in that, In step (4), the shell removal is specifically: covering the mold shell with insulation cotton, naturally cooling for 6 h, and then removing the shell.
10. A method of controlling the growth of a single crystal blade from a secondary dendrite according to claim 9, wherein The thickness of the insulation cotton cover is 20-40 mm.