CN115069979A - Process method for inhibiting columnar crystals on surface of inner cavity of isometric crystal hollow turbine blade - Google Patents
Process method for inhibiting columnar crystals on surface of inner cavity of isometric crystal hollow turbine blade Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 52
- 230000002401 inhibitory effect Effects 0.000 title claims abstract description 16
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- 239000011248 coating agent Substances 0.000 claims abstract description 40
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- 229910045601 alloy Inorganic materials 0.000 claims abstract description 26
- 239000000956 alloy Substances 0.000 claims abstract description 26
- CRHLEZORXKQUEI-UHFFFAOYSA-N dialuminum;cobalt(2+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Al+3].[Al+3].[Co+2].[Co+2] CRHLEZORXKQUEI-UHFFFAOYSA-N 0.000 claims abstract description 20
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- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000011257 shell material Substances 0.000 claims description 40
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
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- 239000000463 material Substances 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 8
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- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical group Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
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- 229910017052 cobalt Inorganic materials 0.000 description 16
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 14
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- 238000005495 investment casting Methods 0.000 description 11
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- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(II) oxide Inorganic materials [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 3
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C23/00—Tools; Devices not mentioned before for moulding
- B22C23/02—Devices for coating moulds or cores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/12—Treating moulds or cores, e.g. drying, hardening
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
Abstract
The invention relates to the technical field of precise casting of turbine blades of gas turbine engines, in particular to a process method for inhibiting columnar crystals on the surface of an inner cavity of an isometric crystal hollow turbine blade, which comprises the following steps: mixing a cobalt aluminate refiner and silica sol in proportion to form refiner slurry for a core, coating the prepared slurry on the surface of the core, pressing a wax mold on the dried core to form a tree group, and forming a hollow turbine blade shell after multiple slurry hanging and sand blasting; by adopting isometric crystal high-temperature alloy casting and cutting and depoling corrosion, the hollow turbine blade with uniform surface grain size and no columnar crystal on the surface of the inner cavity is obtained. According to the process method for inhibiting columnar crystals on the surface of the inner cavity of the isometric hollow turbine blade, the cobalt aluminate refiner on the surface of the core is used for increasing the nucleation core to refine the grain size of the surface of the inner cavity, the growth of the columnar crystals is inhibited, and the blade scrapping loss caused by the columnar crystals is remarkably reduced on the premise of not influencing the surface finish degree of the inner cavity and the wall thickness of a casting.
Description
Technical Field
The invention relates to the technical field of precise casting of turbine blades of gas turbine engines, in particular to a process method for inhibiting columnar crystals on the surface of an inner cavity of an isometric crystal hollow turbine blade.
Background
Because of its good comprehensive performance and low manufacturing cost, the isometric crystal superalloy is widely applied to thermal end key components such as aeroengines and turbine blades of ground combustion engines. In order to improve the overall performance such as the fatigue life of the equiaxed superalloy turbine blade, it is often desirable to obtain fine and uniform equiaxed grains. In the field of precision casting, the refined crystal grains are generally subjected to a mechanical method, a thermal control method and a chemical method, the mechanical method and the thermal control method are less limited by equipment and are widely applied due to simplicity and practicability. The chemical method is to add heterogeneous nucleating agent to increase the crystal core of liquid metal during solidification to achieve the effect of grain refinement, and can be generally divided into surface refinement and integral refinement. The integral refining is to add a proper refiner into the melt after the high-temperature alloy is melted, the crystal grains in the whole casting are obviously refined under the action of the nucleating agent, but the added nucleating agent is easy to form oxide inclusions in the melt to become a fatigue source, so that the control difficulty of the integral refining process is high, the application is limited, the surface refining is to coat the refiner on the surface of a shell to refine the crystal grains on the surface of the casting, and the process is simple and does not introduce inclusions, so that the process becomes the mainstream process of the existing fine-grain casting.
Although the grain on the outer surface of the turbine blade can be refined by coating the refiner on the surface of the shell, a higher pouring temperature is usually required for obtaining a casting with good internal metallurgical quality, transverse columnar crystals are particularly easily formed on the surface of an inner cavity at the position of a cleft at the tail edge of the blade and the like, and the transverse columnar crystals are not usually allowed by the blade acceptance technical conditions because the transverse columnar crystals deteriorate the performance of the blade. The vertical columnar crystal on the surface of the inner cavity is extremely easy to form in the isometric crystal turbine blade with the opening structure at the tail edge, and the quality and the qualification rate of the turbine blade are obviously reduced.
Through retrieval, the Chinese patent number: CN101417320A discloses a cobaltous oxide metal alloy surface refiner, which consists of cobaltous oxide, corundum powder and molybdenum alloy, wherein the weight content of cobaltous oxide is 55-75%; 10-30% of corundum powder; the weight content of the molybdenum alloy is 15-35%. The components are proportioned, and the powder materials are uniformly mixed through low-temperature heating drying, ball milling, high-temperature roasting and secondary ball milling; the method is mainly suitable for the field of high-temperature alloy investment casting and is used for refining crystal grains on the outer surface of a casting; the refiner has different formulas, and the refiner slurry does not contain molybdenum alloy;
chinese patent No.: CN203235914U discloses a shuttering of a plum blossom test bar for a high temperature alloy, which comprises a shuttering coating, wherein a shuttering refinement layer is attached to the inner wall of the shuttering coating. The utility model discloses to the nickel base that has the test bar specification to require for the plum blossom test bar in the order, cobalt base superalloy, some alloys cause the structure mechanical properties difference great because of chemical composition segregation, adopt can improve the near surface structure after the crystalline grain refines, thereby improved mechanical properties, have important meaning to developing the alloy, also can exert the latent energy of material through the grain size; the method is mainly suitable for manufacturing the mould shell of the high-temperature alloy plum blossom test bar and is used for refining the grain size of the outer surface of the test bar; the method has different applicable objects and refining processes, and is suitable for controlling the grain size of the surface of the inner cavity of the isometric crystal hollow turbine blade;
chinese patent No.: CN104384449A discloses a method for controlling grain size of a precision casting turbine blade, which comprises overlapping interference ribs on the exhaust edge of a casting wax mold, coating surface layer slurry on the surface layer, coating back layer coating as a reinforcing layer, dewaxing and roasting, taking out residual wax, placing the casting shell into a heat-insulating barrel, heating and pouring. The method is mainly suitable for controlling the grain size of the outer surface of the high-temperature alloy turbine blade; the grain size control process is completely different, the patent adopts a chemical method of adding cobalt aluminate, and the grain size is controlled by overlapping interference ribs to realize the heat preservation effect.
Therefore, the invention needs to improve the grain refining process in the existing precision casting process and inhibit the formation of columnar grains on the surface of the inner cavity.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a process method for inhibiting columnar crystals on the surface of an inner cavity of an equiaxial hollow turbine blade.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention provides a process method for inhibiting columnar crystals on the surface of an inner cavity of an isometric crystal hollow turbine blade, which comprises the following steps:
(1) mixing and uniformly stirring a cobalt aluminate refiner and silica sol in proportion to form core refiner slurry;
(2) uniformly coating the surface of the core with the refiner slurry by adopting a fine brush or a spraying mode;
(3) naturally airing the core coated with the refiner slurry, pressing a wax mold, and combining the wax mold into a tree set;
(4) coating a plurality of layers of shell materials on the outer part of the wax module tree, and drying and dewaxing to obtain a hollow turbine blade shell;
(5) casting the hollow turbine blade shell by adopting isometric crystal high-temperature alloy;
(6) the cooled casting module is subjected to shell cleaning and cutting to obtain a single hollow blade casting;
(7) carrying out core removal treatment on the hollow blade casting in 160-200 ℃ alkaline solution;
(8) and (3) carrying out grain size corrosion on the hollow blade by adopting an acidic corrosive to obtain the hollow turbine blade with uniform surface grain size and no columnar crystal on the surface of the inner cavity.
Preferably, the ratio of the cobalt aluminate refiner to the silica sol in the core refiner slurry is 1.0-1.5: 1 by weight.
Preferably, the stirring time of the core refiner slurry is 2 hours, and the viscosity of the core refiner slurry is controlled to be 5-10 s.
Preferably, when the surface of the core is coated with the refiner slurry, the repeated coating times are not more than 3, and the thickness of the refiner coating is not more than 10 μm.
Preferably, the core coated with the refiner slurry is naturally aired for 6-8 hours, and then a wax mold is pressed.
Preferably, the external coating type shell material of the wax pattern tree is 4-9 layers of shell materials, and the 1 st coating material contains a cobalt aluminate refiner with the content of 10-20%.
Preferably, the isometric crystal superalloy pours a shell at 1400-1600 ℃.
Preferably, the alkaline solution is 30-65% potassium hydroxide, and the temperature is 160-200 ℃.
Preferably, the acidic corrosive agent is ferric chloride: hydrochloric acid: 275g/L water: 120 g/L: balancing;
the balance is the water content which is left after the iron trichloride and the hydrochloric acid are subtracted according to the calculation of each liter of corrosive agent.
Compared with the prior art, the invention has the following beneficial effects:
the invention relates to a process method for inhibiting columnar crystals on the surface of an inner cavity of an isometric crystal hollow turbine blade, which refines the grain size of the surface of the inner cavity by utilizing the effect of a cobalt aluminate refiner on the surface of a core to increase nucleation cores and inhibits the growth of the columnar crystals.
Further, cobalt aluminate is reduced into metal cobalt in the casting process, the crystal structure of the metal cobalt is close to that of a high-temperature alloy matrix, a good lattice matching relation is achieved, a large number of crystal cores are formed on the surface of the inner cavity, and therefore crystal grains on the surface of the inner cavity are refined to inhibit columnar crystal growth; and because the high-temperature alloy contains cobalt element, the addition of the cobalt aluminate refiner does not have adverse effect on the components and the performance of the turbine blade.
Furthermore, the core is a porous material, when refiner slurry with proper viscosity is coated on the surface of the core, the slurry can permeate into pores on the surface layer of the core, the surface smoothness of the core can not be obviously changed, the size change of the core is not more than 10 μm, and the surface quality and the wall thickness size of the inner cavity of the blade can be effectively ensured while the columnar crystals on the surface of the inner cavity are inhibited.
Drawings
FIG. 1 is a photograph of an isometric turbine blade core coated with a refiner paste according to example 1 of the present invention;
FIG. 2 is a grain size photograph of the refiner coated portion of the equiaxial turbine blade in example 1 of the present invention;
FIG. 3 is a photograph of an isometric turbine blade core coated with a refiner slurry according to example 2 of the present invention;
FIG. 4 is a grain size photograph of the coated refiner portion of an equiaxial turbine blade in accordance with example 2 of the present invention;
FIG. 5 is a photograph of columnar crystals on the surface of the inner cavity of the exhaust edge of the K6509 alloy blade in comparative example 1;
FIG. 6 is a photograph of columnar crystals on the surface of the inner cavity of the exhaust edge of the K447A alloy blade in comparative example 2 of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The sample of the preferred embodiment is a precision casting of a certain model of an aeroengine K6509 cobalt-based isometric crystal high-temperature alloy hollow turbine blade, and the following pretreatment method is adopted:
(1) mixing and uniformly stirring a cobalt aluminate refiner and silica sol according to the weight ratio of 1:1, wherein the stirring time is 2 hours, and the viscosity is controlled to be 5s, so as to form core refiner slurry;
(2) uniformly coating the surface of the core with the refiner slurry by adopting a fine brush or spraying mode, and repeatedly coating for 3 times, wherein the thickness of the refiner coating is not more than 10 mu m;
(3) naturally airing the core coated with the refiner slurry for 6h, pressing a wax pattern, and combining the wax patterns into a tree set;
(4) coating 4 layers of shell materials on the exterior of a wax pattern tree, wherein the 1 st layer of coating material contains 10% of cobalt aluminate refiner, and obtaining a hollow turbine blade shell after drying and dewaxing;
(5) casting the hollow turbine blade shell by using K6509 cobalt-based isometric crystal high-temperature alloy at the casting temperature of 1500 ℃;
(6) performing shell cleaning and cutting on the cooled casting module to obtain a single hollow blade casting;
(7) carrying out core removal treatment on the hollow blade casting in an alkaline solution at 160 ℃; the alkaline solution is 30 percent potassium hydroxide;
(8) performing grain size corrosion on the hollow blade by adopting an acidic corrosive agent to obtain a hollow turbine blade with uniform surface grain size and no columnar crystal on the surface of an inner cavity; the acidic corrosive is ferric trichloride: hydrochloric acid: 275g/L water: 120 g/L: and (4) balancing.
FIG. 1 is a picture of a K6509 cobalt-based equiaxed turbine blade core coated with a refiner slurry, with a blue refiner layer formed on the surface of the core.
FIG. 2 is a grain size photograph of a refiner coated part of a K6509 cobalt-based equiaxed crystal turbine blade, wherein the grain size is uniform and fine equiaxed crystal grains, and columnar crystal grains do not appear.
(II) example 2
The sample of the preferred embodiment is a precision casting of a nickel-based isometric crystal superalloy hollow turbine blade of an aero-engine K447A of a certain model, and the following pretreatment method is adopted:
(1) mixing and uniformly stirring a cobalt aluminate refiner and silica sol according to the weight ratio of 1.5:1 for 2 hours, and controlling the viscosity to be 10s to form core refiner slurry;
(2) uniformly coating the surface of the core with the refiner slurry by adopting a fine brush or spraying mode, and repeatedly coating for 3 times, wherein the thickness of the refiner coating is not more than 10 mu m;
(3) naturally airing the core coated with the refiner slurry for 8h, pressing a wax pattern, and combining the wax patterns into a tree set;
(4) coating 9 layers of shell materials on the exterior of a wax pattern tree, wherein the 1 st layer of coating material contains 20% of cobalt aluminate refiner, and obtaining a hollow turbine blade shell after drying and dewaxing;
(5) casting the hollow turbine blade shell by adopting K447A nickel-based isometric crystal superalloy, wherein the casting temperature is 1500 ℃;
(6) performing shell cleaning and cutting on the cooled casting module to obtain a single hollow blade casting;
(7) carrying out core removal treatment on the hollow blade casting in an alkaline solution at 200 ℃; the alkaline solution is potassium hydroxide with the concentration of 65 percent;
(8) performing grain size corrosion on the hollow blade by adopting an acidic corrosive agent to obtain a hollow turbine blade with uniform surface grain size and no columnar crystal on the surface of an inner cavity; the acidic corrosive is ferric trichloride: hydrochloric acid: 275g/L water: 120 g/L: and (4) balancing.
FIG. 3 is a photograph of a K447A nickel-based equiaxed turbine blade insert coated with a refiner slurry to form a blue refiner layer on the surface of the insert.
FIG. 4 is a grain size photograph of the refiner coated part of the K447A nickel-based isometric crystal turbine blade, wherein the grain size is uniform and fine isometric crystal grains, and columnar crystal grains do not appear.
(III) example 3
The sample of the preferred embodiment is a precision casting of a certain model of an aeroengine K6509 cobalt-based isometric crystal high-temperature alloy hollow turbine blade, and the following pretreatment method is adopted:
(1) mixing and uniformly stirring a cobalt aluminate refiner and silica sol according to the weight ratio of 1.25:1 for 2 hours, and controlling the viscosity to be 7.5s to form core refiner slurry;
(2) uniformly coating the surface of the core with the refiner slurry by adopting a fine brush or spraying mode, and repeatedly coating for 3 times, wherein the thickness of the refiner coating is not more than 10 mu m;
(3) naturally airing the core coated with the refiner slurry for 7h, pressing a wax pattern, and combining the wax patterns into a tree set;
(4) coating 6 layers of shell materials on the exterior of a wax pattern tree, wherein the 1 st layer of coating material contains a cobalt aluminate refiner with the content of 15%, and drying and dewaxing to obtain a hollow turbine blade shell;
(5) casting the hollow turbine blade shell by using K6509 cobalt-based isometric crystal high-temperature alloy at the casting temperature of 1500 ℃;
(6) carrying out shell cleaning and cutting on the cooled casting module to obtain a single hollow blade casting;
(7) carrying out core removal treatment on the hollow blade casting in an alkaline solution at 180 ℃; the alkaline solution is potassium hydroxide with the concentration of 50 percent;
(8) performing grain size corrosion on the hollow blade by adopting an acidic corrosive agent to obtain a hollow turbine blade with uniform surface grain size and no columnar crystal on the surface of an inner cavity; the acidic corrosive is ferric trichloride: hydrochloric acid: water 275 g/L: 120 g/L: and (4) balancing.
(fourth) example 4
The sample of the preferred embodiment is a precision casting of a hollow turbine blade made of a cobalt-based isometric crystal high-temperature alloy of an aero-engine K6509 of a certain model, and the difference from the embodiment 3 is that the shell of the hollow turbine blade is cast by adopting the cobalt-based isometric crystal high-temperature alloy K6509 at the casting temperature of 1400 ℃.
(fifth) example 5
The sample of the preferred embodiment is a precision casting of a hollow turbine blade made of a cobalt-based isometric crystal high-temperature alloy of an aero-engine K6509 of a certain model, and the difference from the embodiment 3 is that the shell of the hollow turbine blade is cast by adopting the cobalt-based isometric crystal high-temperature alloy K6509 at the casting temperature of 1600 ℃.
Comparative example 1
The comparative sample is a precision casting of a cobalt-based isometric crystal high-temperature alloy hollow turbine blade of an aero-engine K6509 of a certain model, and the following treatment method is adopted:
(1) directly pressing wax molds without coating refiner slurry on the surface of the core, and combining the wax molds into a tree set;
(2) coating a plurality of layers of shell materials outside the wax module tree, wherein the 1 st layer of coating material contains 10% of cobalt aluminate refiner, and obtaining a hollow turbine blade shell after drying and dewaxing;
(3) casting the hollow turbine blade shell by using K6509 cobalt-based isometric crystal high-temperature alloy at the casting temperature of 1500 ℃;
(4) performing shell cleaning and cutting on the cooled casting module to obtain a single hollow blade casting;
(5) carrying out core removal treatment on the hollow blade casting in an alkaline solution;
(6) the hollow blade is subjected to grain size corrosion by adopting an acidic corrosive, and the blade is found to be scrapped due to the fact that transverse columnar crystals (shown in figure 5) perpendicular to the exhaust edge are formed at the tail edge of the blade.
FIG. 5 is a cylindrical crystal photograph of the surface of the inner cavity of the exhaust edge of the K6509 alloy blade, which is formed without the adoption of the method.
Comparative example 2
The comparative sample is a precision casting of a nickel-based isometric crystal superalloy hollow turbine blade of an aero-engine K447A of a certain model, and the following treatment method is adopted:
(1) directly pressing wax molds without coating refiner slurry on the surface of the core, and combining the wax molds into a tree set;
(2) coating a plurality of layers of shell materials outside the wax module tree, wherein the 1 st layer of coating material contains 10% of cobalt aluminate refiner, and obtaining a hollow turbine blade shell after drying and dewaxing;
(3) casting the hollow turbine blade shell by adopting K447A nickel-based isometric crystal superalloy, wherein the casting temperature is 1500 ℃;
(4) performing shell cleaning and cutting on the cooled casting module to obtain a single hollow blade casting;
(5) carrying out core removal treatment on the hollow blade casting in an alkaline solution;
(6) the hollow blade is subjected to grain size corrosion by adopting an acidic corrosive, and the blade is found to be scrapped due to the fact that transverse columnar crystals (shown in figure 5) perpendicular to the exhaust edge are formed at the tail edge of the blade.
FIG. 6 is a photograph of a columnar crystal on the surface of the inner cavity of the exhaust edge of the K447A blade, which is formed without the use of the present patent.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it is to be understood that all embodiments may be combined as appropriate by one of ordinary skill in the art to form other embodiments as will be apparent to those of skill in the art from the description herein.
Claims (8)
1. A process method for inhibiting columnar crystals on the surface of an inner cavity of an isometric crystal hollow turbine blade is characterized by comprising the following steps:
(1) mixing and uniformly stirring a cobalt aluminate refiner and silica sol in proportion to form core refiner slurry;
(2) uniformly coating the surface of the core with the refiner slurry by adopting a fine brush or a spraying mode;
(3) naturally airing the core coated with the refiner slurry, pressing a wax mold, and combining the wax mold into a tree set;
(4) coating a shell material on the outer part of the wax pattern tree, and drying and dewaxing to obtain a hollow turbine blade shell;
(5) casting the hollow turbine blade shell by adopting isometric crystal high-temperature alloy;
(6) the cooled casting module is subjected to shell cleaning and cutting to obtain a single hollow blade casting;
(7) carrying out core removal treatment on the hollow blade casting in 160-200 ℃ alkaline high-temperature solution;
(8) and (3) carrying out grain size corrosion on the hollow blade by adopting an acidic corrosive to obtain the hollow turbine blade with uniform surface grain size and no columnar crystal on the surface of the inner cavity.
2. The process method for inhibiting the columnar crystals on the surface of the inner cavity of the blade of the isometric hollow turbine as claimed in claim 1, wherein the ratio of the cobalt aluminate refiner to the silica sol in the core refiner slurry is 1.0-1.5: 1 by weight.
3. The process method for inhibiting the columnar crystals on the surface of the inner cavity of the blade of the isometric hollow turbine as claimed in claim 2, wherein the stirring time of the core refiner slurry is 2 hours, and the viscosity of the core refiner slurry is controlled to be 5-10 s.
4. The process for inhibiting the columnar crystals on the inner cavity surface of the blade of the isometric hollow turbine as claimed in claim 1, wherein the surface of the core is coated with the refiner slurry, the coating times are not more than 3 times, and the thickness of the refiner coating is not more than 10 μm.
5. The process method for inhibiting the columnar crystals on the surface of the inner cavity of the isometric hollow turbine blade as claimed in claim 1, wherein the core coated with the refiner slurry is naturally aired for 6-8 hours, and then a wax mold is pressed.
6. The process method for inhibiting the columnar crystals on the surface of the inner cavity of the blade of the isometric hollow turbine as claimed in claim 1, wherein the coating type shell material outside the wax module tree is 4-9 layers of shell materials, and the coating material of the 1 st layer contains a cobalt aluminate refiner with the content of 10-20%.
7. The process method for inhibiting the columnar crystals on the surface of the inner cavity of the blade of the isometric hollow turbine as claimed in claim 1, wherein the isometric high-temperature alloy is cast on a shell at the casting temperature of 1400-1600 ℃.
8. The process method for inhibiting the columnar crystals on the surface of the inner cavity of the isometric hollow turbine blade as claimed in claim 1, wherein the acidic corrosive agent is ferric trichloride: hydrochloric acid: 275g/L water: 120 g/L: and (4) balancing.
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