CN115608928A - High-air-permeability directional/single crystal blade ceramic shell and preparation method thereof - Google Patents
High-air-permeability directional/single crystal blade ceramic shell and preparation method thereof Download PDFInfo
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- CN115608928A CN115608928A CN202211334199.2A CN202211334199A CN115608928A CN 115608928 A CN115608928 A CN 115608928A CN 202211334199 A CN202211334199 A CN 202211334199A CN 115608928 A CN115608928 A CN 115608928A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C13/00—Moulding machines for making moulds or cores of particular shapes
- B22C13/08—Moulding machines for making moulds or cores of particular shapes for shell moulds or shell cores
- B22C13/085—Moulding machines for making moulds or cores of particular shapes for shell moulds or shell cores by investing a lost pattern
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
- B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
- C30B11/002—Crucibles or containers for supporting the melt
Abstract
A high-permeability directional/single crystal blade ceramic shell and a preparation method thereof belong to the field of ceramic material preparation. The high-air-permeability directional/single crystal blade ceramic shell sequentially comprises a surface layer, a transition layer, a back layer and a slurry sealing layer from inside to outside; the surface layer, the transition layer and the back layer are respectively provided with corresponding raw materials including powder, a binder, an auxiliary agent and a sand hanging material, and the sealing slurry layer is provided with corresponding raw materials including powder, a binder and an auxiliary agent. Preparing the powder, the binder and the auxiliary agent into corresponding slurry, carrying out slurry coating, then spreading a sand coating material, drying, wetting the surface layer and the transition layer, drying the back layer, coating a multi-layer back layer, finally sealing slurry, and roasting to obtain the high-permeability directional/single crystal blade ceramic shell. The method can effectively solve the metallurgical defects of blade undercasting, surface loosening and the like caused by poor air permeability of the ceramic shell, improve the metallurgical quality and casting qualification rate level of the directional and single crystal blade, increase the safety and reliability of aeroengine and reduce the loss of waste products.
Description
Technical Field
The invention belongs to the technical field of ceramic material preparation, and particularly relates to a high-permeability directional/single crystal blade ceramic shell and a preparation method thereof.
Background
The directional and single crystal blade is a key part in hot end parts of an aeroengine, the casting difficulty is very high, and the requirement on the used ceramic shell is also very high. The ceramic shell is required to have good high-temperature deformation resistance and good air permeability during orientation and precision casting of the single crystal blade. The higher air permeability not only enables the molten metal to effectively exhaust in the solidification process, improves the metallurgical quality, but also can reduce the residual strength of the shell and increase the shelling performance.
The current method of increasing the air permeability of ceramic shells is to add organic fibers to the backing powder. However, the method can affect the high-temperature strength of the shell, and easily causes the defects of shell fire running and the like. At present, no technical method for improving the aspects of powder and sanding grain size grading, wetting layer number, modified silica sol and the like is available. Therefore, research and development of the technical method are necessary.
Disclosure of Invention
The invention aims to improve the air permeability of the ceramic shell of the directional/single crystal blade and improve the comprehensive performance of the ceramic shell on the premise of ensuring the strength of the shell. The method can effectively solve the metallurgical defects of blade undercasting, surface loosening and the like caused by poor air permeability of the ceramic shell, improve the metallurgical quality and casting qualification rate level of the directional and single crystal blade, increase the safety and reliability of aeroengine and reduce the loss of waste products.
In order to realize the purpose, the invention adopts the following technical scheme:
the invention provides a high-permeability oriented/single crystal blade ceramic shell which sequentially comprises a surface layer, a transition layer, a back layer and a sealing slurry layer from inside to outside;
the raw materials adopted by the surface layer are surface layer powder, a binder, an auxiliary agent and a surface layer sand coating material;
the powder material of the surface layer is fused corundum powder or fused mullite powder, the granularity range is 270-320 meshes, the granularity distribution is that the granularity range of D10 is (1-5) mu m, the granularity range of D50 is (10-25) mu m, and the granularity range of D90 is (40-65) mu m.
The binder is selected from modified silica sol or quick-drying silica sol.
The auxiliary agent is selected from a wetting agent and a defoaming agent, the wetting agent is fatty alcohol-polyoxyethylene ether, and the defoaming agent is fatty alcohol, preferably n-octanol.
The surface layer sand-hanging material is fused corundum or fused mullite sand with the granularity of 80-100 meshes.
The transition layer adopts the raw materials of transition layer powder, a binder, an auxiliary agent and a transition layer sand-hanging material;
the powder material of the transition layer is electric melting mullite powder, wherein SiO in the electric melting mullite powder 2 The mass percentage of the component (A) is 3-8%, the particle size range is 270-320 meshes, the particle size distribution is that the D10 particle size range is (3-9) mu m, the D50 particle size range is (20-45) mu m, and the D90 particle size range is (50-95) mu m.
The binder is selected from modified silica sol or quick-drying silica sol.
The auxiliary agent is a wetting agent and a defoaming agent, the wetting agent is fatty alcohol-polyoxyethylene ether, and the defoaming agent is fatty alcohol, preferably n-octyl alcohol.
The sand hanging material of the transition layer is fused corundum or fused mullite sand with the granularity of 36-60 meshes.
The back layer is prepared from the raw materials of back layer powder, a binder, an auxiliary agent and a back layer sand hanging material;
the back layer powder is electrofused mullite powder, wherein SiO in the electrofused mullite powder 2 The mass percentage of the component (A) is 3-8%, the particle size range is 270-320 meshes, the particle size distribution is that the D10 particle size range is (3-9) mu m, the D50 particle size range is (20-45) mu m, and the D90 particle size range is (50-95) mu m.
The binder is selected from modified silica sol or quick-drying silica sol.
The auxiliary agent is selected from a wetting agent and a defoaming agent, the wetting agent is fatty alcohol-polyoxyethylene ether, and the defoaming agent is fatty alcohol, preferably n-octanol.
The back layer sand hanging material is fused corundum or fused mullite sand with the granularity of 16-24 meshes.
The adopted raw materials of the sealing slurry layer are sealing slurry layer powder, a binder and an auxiliary agent;
the powder of the sealing slurry layer is fused mullite powder, wherein SiO in the fused mullite powder 2 The mass percentage of the component (A) is 3-8%, the particle size range is 270-320 meshes, the particle size distribution is that the D10 particle size range is (3-9) mu m, the D50 particle size range is (20-45) mu m, and the D90 particle size range is (50-95) mu m.
The binder is selected from modified silica sol or quick-drying silica sol.
The auxiliary agent is a wetting agent and a defoaming agent, the wetting agent is fatty alcohol-polyoxyethylene ether, and the defoaming agent is fatty alcohol, preferably n-octyl alcohol.
The total number of the surface layer, the transition layer and the back layer is determined according to the structure and the size of the blade, and the total number of the layers is preferably 4-6, wherein the surface layer is 1, the transition layer is 1 and the back layer is 2-4.
The invention relates to a preparation method of a high-permeability directional/single crystal blade ceramic shell, which comprises the following steps:
s1: preparing surface layer slurry:
mixing the surface powder, the binder and the auxiliary agent to obtain surface slurry; wherein, according to the mass ratio, the surface layer powder: adhesive: wetting agent: the defoaming agent is (2.6-3.9): 1:0.005:0.005;
s2: preparing slurry of a transition layer:
according to the mass ratio, the transition layer powder material: adhesive: wetting agent: the defoaming agent is (2.2-2.8): 1:0.005:0.005, mixing the transition layer powder with a binder to obtain transition layer slurry;
s3: preparing back layer slurry:
according to the mass ratio, the back layer powder material: adhesive: wetting agent: the defoaming agent is (1.7-2.3): 1:0.005:0.005, mixing the back layer powder with a binder to obtain back layer slurry;
s4: preparing slurry of a sealing layer:
according to the mass ratio, the sealing slurry layer powder material: adhesive: wetting agent: the defoaming agent is (2-2.7): 1:0.005:0.005, mixing the sealing layer powder with a binder to obtain sealing layer slurry;
s5: preparing a wetting agent:
the wetting agent is selected from alkaline silica sol or quick-drying silica sol, wherein SiO is contained in the wetting agent according to the mass percentage 2 The content is 29 to 31 percent.
S6: a wetting mode:
and (3) a surface layer wetting mode, namely soaking the module coated with the surface layer into a wetting agent for 1-4 s, taking out, and standing for 10-40 s. And (3) wetting the transition layer, namely immersing the module coated with the transition layer into a wetting agent for 2-5 s, taking out, and standing for 20-50 s to obtain the wetted module.
The coating process is a mode of a multilayer ceramic shell for investment casting, wherein the process of coating the surface layer comprises the following steps: after the module is degreased and dried, coating surface layer slurry, then spreading a surface layer sand coating material, and drying;
the process of coating the transition layer comprises the following steps: and (5) carrying out slurry hanging and sanding processes of the transition layer.
The process of coating the back layer comprises the following steps: and carrying out the processes of slurry coating and sanding on the back layer.
Wherein, the wetting treatment is needed after the surface layer and the transition layer are coated in the coating process.
The method comprises the following specific steps: coating a transition layer after finishing the surface layer drying, putting the module into wetting liquid for wetting for 1-4 s, taking out and standing for 10-40 s, then coating transition layer slurry, controlling the slurry, then coating corundum sand or fused mullite sand, and then drying.
And after the transition layer is dried, putting the module into wetting liquid for wetting for 2-5 s, taking out and standing for 20-50 s, then coating back layer slurry, controlling the slurry, then coating fused corundum sand or fused mullite sand, and then drying.
And then coating 2-4 back layers and sealing slurry, wherein the back layers and the sealing slurry layer are not wetted, and drying until the ceramic shell is manufactured.
S7: roasting:
and (3) dewaxing and roasting the ceramic shell to complete the shell manufacturing process to obtain the high-permeability directional/single crystal blade ceramic shell.
In the preparation method of the high-permeability oriented/single crystal blade ceramic shell, the binder is modified silica sol or quick-drying silica sol, the modified silica sol is prepared by modifying alkaline silica sol and adding a reinforcing agent, wherein the reinforcing agent accounts for 5-12% of the modified silica sol by mass, and is selected from polyvinyl acetate emulsion with the colloid particle size of 100-200 nm.
In the S1, the viscosity of the prepared surface layer slurry is 23S-37S (detected by a 6# viscometer).
In the preparation method of the high-permeability directional/single crystal blade ceramic shell, siO is used as a binder 2 The mass percentage of the fertilizer is 29-31%.
In S2, the viscosity of the prepared transition layer slurry is 11S-22S (detected by a No. 6 viscometer).
In S3, the viscosity of the back layer slurry is 6S to 12S (measured by a # 6 viscometer).
In the S4, the viscosity of the prepared sealing slurry layer is 13S-19S (detected by a No. 6 viscometer).
The invention relates to a high-permeability directional/single crystal blade ceramic shell and a preparation method thereof, which have the beneficial effects that:
the method starts from the aspects of refractory powder, sand, a binder, a wetting mode and the like, and obviously improves the air permeability of the oriented and single crystal blade ceramic shell from the aspect of optimizing the shell organization structure on the premise of not changing the whole formula system of the shell by designing reasonable powder, optimizing the grain size distribution of the refractory material, modifying silica sol and optimizing the number and the mode of wetting layers.
Compared with the prior art, the method does not obviously increase the material cost and the process cost, and does not cause adverse factors such as strength reduction caused by changing the air permeability. The air permeability of the shell can be increased by more than 15%. The problems of metallurgical defects such as blade undercasting, surface loosening and the like caused by poor air permeability can be solved, the qualification rate of the directional/single crystal blade can be improved by more than 30%, and the cost of waste products caused by the defects is greatly reduced.
The method is verified by field practice, so that the air permeability of the shell can be effectively improved, the harsh requirements of the directional/single crystal blade on the strength and the air permeability of the shell can be met, the problems of insufficient casting, loose surface and the like of the blade are avoided, and the qualified rate of the blade is improved.
The method has higher economic and popularization values in the field of precision casting.
The method can effectively improve the comprehensive performance of the ceramic shell of the directional/single crystal blade, solve the metallurgical defect of the casting process of the directional/single crystal blade and improve the qualification rate.
Detailed Description
The present invention will be described in further detail with reference to examples.
In the following examples, polyvinyl acetate emulsions are used as reinforcing agents.
In the following examples, the wetting agent is fatty alcohol-polyoxyethylene ether and the antifoaming agent is n-octanol.
In the following examples, the viscosity was measured by the following method: the method comprises the steps of using a standard flow cup (6 # viscometer) with the capacity of 100mL and the outflow hole of phi 6mm +/-phi 0.2mm, blocking a small hole in the bottom of the flow cup by a finger, filling a measured material into the flow cup, loosening the finger after the liquid level is flush with the upper edge of the flow cup, recording the outflow time of the measured material flowing out from the small hole in the lower end by a stopwatch, finishing timing after all the materials in the flow cup flow out, wherein the time is the year of the material, measuring three times each time, and taking an average value, wherein the error is not more than 2 s.
The first scheme comprises the following steps:
the method comprises the following steps: and preparing surface layer slurry.
Mixing and stirring 2.8 parts of fused corundum powder (the granularity is 320 meshes), 1 part of mixed liquid of alkaline silica sol and a reinforcing agent (serving as modified silica sol), 0.005 part of wetting agent and 0.005 part of defoaming agent to prepare surface layer slurry, wherein the viscosity of the surface layer slurry is 25 +/-2 s. Wherein the grain size distribution of the fused corundum powder is D10 (2 +/-1) mu m, D50 (15 +/-1) mu m, D90: (45. + -. 1) μm. In the modified silica sol, the silica sol accounts for 94% by mass, and the reinforcing agent accounts for 6% by mass.
Step two: and preparing transition layer slurry.
Mixing and stirring 2.3 parts of electrofused mullite powder (the granularity is 320 meshes), 1 part of mixed solution of alkaline silica sol and a reinforcing agent (serving as modified silica sol), 0.005 part of wetting agent and 0.005 part of defoaming agent to prepare transition layer slurry, wherein the viscosity of the transition layer slurry is (12 +/-1) s. Wherein SiO in the electric melting mullite powder 2 The content is 4%, the grain size distribution is D10 (6 +/-1) mu m, D50: (28 +/-1) mu m, and D90 (65 +/-1) mu m. In the modified silica sol, the alkaline silica sol accounts for 95 percent by mass, and the reinforcing agent accounts for 5 percent by mass.
Step three: preparing the back layer slurry.
1.8 parts of electrofused mullite powder (with the granularity of 300 meshes), 1 part of a mixed solution of alkaline silica sol and a reinforcing agent (serving as modified silica sol), 0.005 part of a wetting agent and 0.005 part of an antifoaming agent are mixed and stirred to prepare back layer slurry, and the viscosity of the back layer slurry is 6s on average. Wherein SiO in the electric melting mullite powder 2 The content is 4%, and the grain size distribution is D10 (6 +/-1) mu m, D50 (28 +/-1) mu m and D90 (65 +/-1) mu m. The mixed solution contains 94% of alkaline silica sol and 6% of reinforcing agent.
Step four: and preparing sealing slurry layer slurry.
Mixing and stirring 2.5 parts of fused mullite powder (with the granularity of 300 meshes) and a mixed solution (serving as modified silica sol) of 1 part of alkaline silica sol and a reinforcing agent, 0.005 part of a wetting agent and 0.005 part of an antifoaming agent to prepare sealing slurry layer slurry, wherein the viscosity of the sealing slurry layer slurry is (15 +/-1) s. Wherein, the granularity gradation of the electric melting mullite powder is D10: (6 +/-1) mu m, D50 (28 +/-1) mu m and D90 (65 +/-1) mu m. In the mixed solution, the alkaline silica sol accounts for 90 percent by mass, and the reinforcing agent accounts for 10 percent by mass. The transition layer can be mixed with the sealing slurry layer when the viscosity is the same.
Step five: and leaching the surface layer slurry by the die set, controlling the slurry, then spreading fused corundum sand or fused mullite sand of 100 meshes, and then drying.
Step six: the module was immersed in the quick drying silica sol for 2s and then removed and allowed to stand for 20s. And (3) immersing the module into the transition layer slurry, controlling the material, spreading 60-mesh fused corundum sand or fused mullite sand, and drying.
Step seven: the module was immersed in the quick drying silica sol for 3s and then taken out and left to stand for 30s. And (3) immersing the module into the back layer slurry, controlling the material, and spreading 24-mesh fused corundum sand or fused mullite sand. And then dried.
Step eight: and (3) immersing the module into the back layer slurry, controlling the material, and spreading 24-mesh fused corundum sand or fused mullite sand. And then dried.
Step nine: and repeating the step eight, coating 4 layers of back layers and forming 6 layers of shells.
Step ten: and (4) after the sealing slurry layer slurry is immersed, taking out and drying. Wherein the seal coat slurry viscosity is 15s.
Step eleven: dewaxing the coated shell.
Step twelve: and roasting the coated shell to obtain the high-permeability directional/single crystal blade ceramic shell.
Scheme two is as follows:
the method comprises the following steps: and preparing surface layer slurry.
3.6 parts of electrofused mullite powder (with the granularity of 320 meshes), 1 part of a mixed solution of silica sol and a reinforcing agent (used as modified silica sol), 0.005 part of a wetting agent and 0.005 part of an antifoaming agent are mixed and stirred to prepare a surface layer slurry, and the viscosity of the surface layer slurry is (35 +/-2) s. Wherein, the granularity gradation of the electric melting mullite powder is D10: (3 +/-1) mu m, D50 (20 +/-1) mu m and D90 (56 +/-1) mu m. The modified silica sol comprises 88 mass percent of silica sol and 12 mass percent of reinforcing agent.
Step two: and preparing transition layer slurry.
Mixing and stirring 2.7 parts of electrically-fused mullite powder (with the granularity of 300 meshes) and a mixed solution (serving as modified silica sol) of 1 part of silica sol and a reinforcing agent, 0.005 part of a wetting agent and 0.005 part of an antifoaming agent to prepare a transition layer slurry, wherein the viscosity of the transition layer slurry is (20 +/-2) s. Wherein SiO in the electric melting mullite powder 2 The mass percentage of (A) is 7%,the grain size distribution is D10 (7 +/-1) mu m, D50 (32 +/-1) pm and D90 (85 +/-1) mu m. The modified silica sol comprises 90% of silica sol and 10% of reinforcing agent.
Step three: a backing layer slurry is formulated.
1.8 parts of electrofused mullite powder (with the granularity of 300 meshes), 1 part of mixed solution of alkaline silica sol and a reinforcing agent (serving as modified silica sol), 0.005 part of wetting agent and 0.005 part of defoaming agent are mixed and stirred to prepare back layer slurry, and the viscosity of the back layer slurry is (7 +/-1) s. Wherein SiO in the electric melting mullite powder 2 The content of the compound is 7 percent by mass, and the particle size distribution is D10 (7 +/-1) mu m, D50 (32 +/-1) mu m and D90 (85 +/-l) mu m. In the mixed solution, the alkaline silica sol accounts for 90 percent by mass, and the reinforcing agent accounts for 10 percent by mass.
Step four: and (4) preparing sealing slurry layer slurry.
Mixing and stirring 2.6 parts of electrically-fused mullite powder (with the granularity of 300 meshes) and a mixed solution (serving as modified silica sol) of 1 part of alkaline silica sol and a reinforcing agent, 0.005 part of a wetting agent and 0.005 part of an antifoaming agent to prepare sealing slurry, wherein the viscosity of the sealing slurry is (18 +/-1) s. Wherein, the granularity gradation of the fused mullite is D10 (7 +/-1) mu m, D50 (32 +/-1) mu m and D90 (85 +/-1) mu m. In the mixed solution, the alkaline silica sol accounts for 92% by mass, and the reinforcing agent accounts for 8% by mass. The transition layer can be mixed with the sealing slurry layer when the viscosity is the same.
Step five: and leaching the surface layer slurry by the die set, controlling the slurry, then spreading 80-mesh fused corundum sand or fused mullite sand, and then drying.
Step six: the module was immersed in the alkaline silica sol for 3s and then taken out and left to stand for 40s. And (3) immersing the module into the transition layer slurry, controlling the material, and spreading 46-mesh fused corundum sand or fused mullite sand. And then dried.
Step seven: the module was immersed in the alkaline silica sol for 5s and then removed and left to stand for 35s. And (3) immersing the module into the back layer slurry, controlling the material, and spreading 16-mesh fused corundum sand or fused mullite sand. And then dried.
Step eight: and (3) immersing the module into the back layer slurry, controlling the material, and spreading 16-mesh fused corundum sand or fused mullite sand. And then dried.
Step nine: and repeating the step eight, coating 2 layers of back layers to form a 4-layer shell.
Step ten: coating a sealing slurry layer and performing annealing. Wherein the sealing layer slurry viscosity is 18s.
Step eleven: and dewaxing the coated shell.
Step twelve: and roasting the coated shell to obtain the high-permeability directional/single crystal blade ceramic shell.
And a third scheme is as follows:
the method comprises the following steps: and preparing surface layer slurry.
3 parts of fused corundum powder (the granularity is 320 meshes), 1 part of quick-drying silica sol, 0.005 part of wetting agent and 0.005 part of defoaming agent are mixed and stirred to prepare surface layer slurry, and the viscosity of the surface layer slurry is 29 +/-2 s. Wherein the grain size distribution of the fused corundum powder is D10 (3 +/-1) mu m, D50 (18 +/-1) mu m and D90 (47 +/-1) mu m.
Step two: and preparing slurry of the transition layer.
Mixing and stirring 2.5 parts of electrically-fused mullite powder (the granularity is 320 meshes), 1 part of quick-drying silica sol, 0.005 part of wetting agent and 0.005 part of defoaming agent to prepare transition layer slurry, wherein the viscosity of the transition layer slurry is (17 +/-2) s. Wherein SiO in the electric melting mullite powder 2 The content is 8%, and the grain size distribution is D10 (5 +/-1) mu m, D50 (35 +/-1) mu m and D90 (70 +/-1) mu m.
Step three: a backing layer slurry is formulated.
2.3 parts of electrofused mullite powder (the granularity is 300 meshes), 1 part of quick-drying silica sol, 0.005 part of wetting agent and 0.005 part of defoaming agent are mixed and stirred to prepare back layer slurry, and the viscosity of the back layer slurry is (12 +/-1) s. Wherein SiO in the electric melting mullite powder 2 The content of the components is 4 percent by mass, and the particle size distribution is D10 (5 +/-1) mu m, D50 (35 +/-1) mu m and D90 (70 +/-1) mu m.
Step four: and preparing sealing slurry layer slurry.
Mixing and stirring 2.5 parts of electrically-fused mullite powder (the granularity is 300 meshes), 1 part of mixed solution of alkaline silica sol and a reinforcing agent (serving as modified silica sol), 0.005 part of wetting agent and 0.005 part of defoaming agent to prepare sealing slurry, wherein the viscosity of the sealing slurry is (15 +/-1) s. Wherein, the granularity gradation of the electric melting mullite is D10 (5 +/-1) mu m, D50 (35 +/-1) mu m and D90 (70 +/-1) mu m. The transition layer can be mixed with the sealing slurry layer when the viscosity is the same.
Step five: and leaching the surface layer slurry by the die set, controlling the slurry, then spreading 80-mesh fused corundum sand or fused mullite sand, and then drying.
Step six: the module was immersed in the quick drying silica sol for 3s and then taken out and left to stand for 30s. And (3) immersing the die set into the transition layer slurry, controlling the material, and spreading 46-mesh fused corundum sand or fused mullite sand. And then dried.
Step seven: the die set is immersed in the quick-drying silica sol for 3s, and then taken out and kept stand for 35s. And (3) immersing the module into the back layer slurry, controlling the material, and spreading 24-mesh fused corundum sand or fused mullite sand. And then dried.
Step eight: and (3) immersing the module into the back layer slurry, controlling the material, and spreading 24-mesh fused corundum sand or fused mullite sand. And then dried.
Step nine: and repeating the step eight, coating 3 layers of back layers to form a 5-layer shell.
Step ten: and coating a sealing slurry layer, and drying, wherein the viscosity of the sealing slurry layer is 15s.
Step eleven: and dewaxing the coated shell.
Step twelve: and roasting the coated shell.
The air permeability of the above examples was studied and it was found that the air permeability was improved by 12-15% on the basis of the original scheme without optimization of the powder and sanding size grading, improvement of the wetting process and modification of the binder, respectively.
Comparative example
The same as in example 1, except that the addition of the reinforcing agent reduced the wet strength of the shell and affected the air permeability of the shell to some extent.
Claims (10)
1. The ceramic shell of the high-permeability directional/single crystal blade is characterized by comprising a surface layer, a transition layer, a back layer and a sealing slurry layer from inside to outside in sequence.
2. The ceramic shell mold of claim 1, wherein the facing layer is made of facing powder, binder, auxiliary agent and facing sand;
the powder material of the surface layer is fused corundum powder or fused mullite powder, the granularity range is 270-320 meshes, the granularity distribution is that the granularity range of D10 is 1-5 mu m, the granularity range of D50 is 10-25 mu m, and the granularity range of D90 is 40-65 mu m;
the surface layer sand hanging material is made of fused corundum or fused mullite sand with the granularity of 80-100 meshes.
3. The ceramic shell of high permeability directional/single crystal blade according to claim 1, wherein the transition layer is made of transition layer powder, binder, auxiliary agent and transition layer sand-coating material;
the powder material of the transition layer is electrically fused mullite powder, wherein SiO in the electrically fused mullite powder 2 The mass percentage of the compound is 3-8%, the granularity range is 270-320 meshes, the granularity distribution is that the granularity range of D10 is 3-9 mu m, the granularity range of D50 is 20-45 mu m, and the granularity range of D90 is 50-95 mu m;
the sand hanging material of the transition layer is fused corundum sand or fused mullite sand with the granularity of 36-60 meshes.
4. The highly permeable directional/single crystal blade ceramic shell according to claim 1, wherein the backing layer is made of backing layer powder, binder, auxiliary agent and backing layer sand-coated material;
the back layer powder adopts the fused mullite powder, wherein SiO in the fused mullite powder 2 The mass percentage of the compound is 3-8%, the granularity range is 270-320 meshes, the granularity distribution is that the granularity range of D10 is 3-9 mu m, the granularity range of D50 is 20-45 mu m, and the granularity range of D90 is 50-95 mu m;
the back layer sand hanging material is fused corundum sand or fused mullite sand with the granularity of 16-24 meshes.
5. The ceramic shell mold of high permeability directional/single crystal blade according to claim 1, wherein the slurry layer is made of slurry layer powder, binder, and auxiliary agent;
the powder of the slurry sealing layer is fused mullite powder, wherein SiO in the fused mullite powder 2 The mass percentage of the composite material is 3-8%, the granularity range is 270-320 meshes, the granularity distribution is that the granularity range of D10 is 3-9 mu m, the granularity range of D50 is 20-45 mu m, and the granularity range of D90 is 50-95 mu m.
6. The highly permeable directional/single crystal blade ceramic shell according to any one of claims 2 to 5, wherein the binder is selected from modified silica sol or quick-drying silica sol; in a binder, siO 2 The mass percentage of the composite material is 29 to 31 percent; and/or the auxiliary agent is a wetting agent and a defoaming agent, wherein the wetting agent is fatty alcohol-polyoxyethylene ether, and the defoaming agent is n-octanol.
7. The ceramic shell of high permeability directional single crystal blade according to claim 1 or 2, wherein the total number of the face layer, the transition layer and the back layer is 4-6 according to the blade structure and size, wherein the face layer is 1, the transition layer is 1 and the back layer is 2-4.
8. The method for preparing a ceramic shell of a high permeability directional/single crystal blade according to any one of claims 1 to 7, comprising the steps of:
s1: preparing surface layer slurry:
mixing the surface powder, the binder and the auxiliary agent to obtain surface slurry; wherein, according to the mass ratio, the surface layer powder: adhesive: wetting agent: the defoaming agent is (2.6-3.9): 1:0.005:0.005;
s2: preparing slurry of a transition layer:
according to the mass ratio, the transition layer powder: adhesive: wetting agent: the defoaming agent is (2.2-2.8): 1:0.005:0.005, mixing the transition layer powder and the binder to obtain transition layer slurry;
s3: preparing back layer slurry:
according to the mass ratio, the back layer powder material: adhesive: wetting agent: the defoaming agent is (1.7-2.3): 1:0.005:0.005, mixing the back layer powder with a binder to obtain back layer slurry;
s4: preparing slurry of a sealing layer:
according to the mass ratio, the sealing slurry layer powder material: adhesive: wetting agent: the defoaming agent is (2-2.7): 1:0.005:0.005, mixing the sealing slurry layer powder with a binder to obtain sealing slurry layer slurry;
s5: preparing a wetting agent:
the wetting agent is selected from alkaline silica sol or quick-drying silica sol, wherein SiO is contained in the wetting agent according to the mass percentage 2 The content is 29 to 31 percent;
s6: coating-wetting:
after the module is degreased and dried, coating surface layer slurry, then coating surface layer sand coating materials, and drying to obtain a surface layer coated module;
immersing the module coated with the surface layer into a wetting agent for 1-4 s, then taking out, and standing for 10-40 s;
then coating a transition layer, which specifically comprises the following steps: coating and hanging transition layer slurry, controlling the slurry, then coating corundum sand or electric smelting mullite sand, and then drying to obtain a transition layer coated module;
soaking the module coated with the transition layer into a wetting agent for 2-5 s, then taking out, and standing for 20-50 s to obtain a soaked module;
coating back layer slurry on the soaked module, controlling the slurry, then spreading fused corundum sand or fused silica sand, and then drying;
then sequentially coating 2-4 back layers, coating a sealing slurry layer, and drying to obtain a ceramic shell;
s7: roasting:
and dewaxing and roasting the ceramic shell to obtain the high-permeability directional/single crystal blade ceramic shell.
9. The method for preparing a ceramic shell of a high-permeability directional/single-crystal blade according to claim 8, wherein the binder is selected from modified silica sol or quick-drying silica sol, the modified silica sol is obtained by modifying basic silica sol with an enhancer, the enhancer accounts for 5% -12% of the modified silica sol by mass, and the enhancer is selected from polyvinyl acetate emulsion, and the particle size of the colloid is 100-200 nm.
10. The method of claim 8, wherein the viscosity of the facing slurry is 23s to 37s measured with a 6# viscometer; the viscosity of the prepared transition layer slurry is 11 s-22 s; the viscosity of the prepared back layer slurry is 6 s-12 s; the viscosity of the prepared sealing slurry is 13 s-19 s.
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| CN117483666A (en) * | 2023-11-07 | 2024-02-02 | 东莞市五股机械有限公司 | Preparation method of ceramic shell for precision casting |
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