A slurry for tenon protection during aluminizing and its preparation and use method

Abstract

The present invention discloses a slurry for protecting tenons during the aluminizing process, as well as its preparation and use methods. The anti-aluminizing slurry includes a base layer protective slurry, a transition layer protective slurry, and a surface layer protective slurry. The base layer protective slurry comprises the following components by weight: 50-80 parts zircon powder, 10-50 parts binder, and 1-20 parts deionized water; the transition layer protective slurry comprises the following components by weight: 10-60 parts zirconium oxide, 10-30 parts binder, and 1-20 parts deionized water; and the surface layer protective slurry comprises the following components by weight: 10-30 parts zirconium oxide, 10-40 parts NiAl powder, 10-30 parts binder, and 1-20 parts deionized water. The three protective slurries are uniformly applied to the surface of the blade tenon in sequence and dried at 70-200°C for 20-60 minutes to form an anti-aluminizing protective layer, which provides anti-seepage protection for the blade tenon during the subsequent aluminizing process. The protective slurry of the present invention has good anti-seepage effect, low cost, simple preparation process, convenient removal, no reaction with the base alloy, and strong applicability.

Description

Technical Field

[0001] The present invention relates to the field of high-temperature alloy surface protection, and in particular to a slurry for protecting tenons during aluminizing, and a preparation and use method thereof. Background Art

[0002] Nickel-based single-crystal superalloys are widely used in the manufacture of turbine blades for aircraft engines and gas turbines due to their excellent high-temperature mechanical properties. Turbine blades operate in harsh environments and are often subject to high-temperature oxidation and corrosion, which degrades their high-temperature mechanical properties and shortens their service life. To ensure high-temperature performance and extend blade life, high-temperature protective coatings are often applied to the blade surface. Aluminide coatings and modified aluminide coatings are used for blade protection due to their excellent combined resistance to high-temperature oxidation and corrosion.

[0003] However, aluminizing is a critical step in the preparation of aluminide and modified aluminide coatings on blade surfaces. The tenon of a blade is a critical location subject to high stress during service, and aluminizing the tenon can have adverse effects: the presence of the coating increases its geometric dimensions, affecting blade assembly and preventing it from fitting, leading to mating failure. The coating on the tenon surface can also create sensitive notches, reducing the tenon's mechanical properties and accelerating blade wear and failure. Therefore, to ensure blade performance, the tenon must be protected during the aluminizing process.

[0004] While coating the tenon with a slurry is an effective protective method, the current coating process is cumbersome and complex, leaving residue on the tenon after aluminizing, and the slurry is prone to cracking during high-temperature aluminizing. Therefore, a slurry for tenon protection with excellent anti-seepage effectiveness, low cost, simple preparation, easy removal, and wide applicability is urgently needed. Summary of the Invention

[0005] In view of this, the present invention provides a slurry for protecting tenons during aluminizing and a preparation and use method thereof.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A slurry for protecting tenons during aluminizing is composed of the following three layers: a bottom layer protective slurry, a transition layer protective slurry, and a surface layer protective slurry; wherein the bottom layer protective slurry includes zircon powder, a binder, and deionized water; the transition layer protective slurry includes zirconium oxide, a binder, and deionized water; and the surface layer protective slurry includes zirconium oxide, NiAl powder, a binder, and deionized water.

[0008] Preferably, the weight proportions of the components of the bottom protective slurry are: 50-80 parts of zircon powder, 10-50 parts of binder, and 1-20 parts of deionized water; the weight proportions of the components of the transition layer protective slurry are: 10-60 parts of zirconium oxide, 10-30 parts of binder, and 1-20 parts of deionized water; the weight proportions of the components of the surface layer protective slurry are: 10-30 parts of zirconium oxide, 10-40 parts of NiAl powder, 10-30 parts of binder, and 1-20 parts of deionized water.

[0009] Preferably, the zircon powder is high-purity zircon powder with a particle size of 200-350 mesh; the zirconium oxide is high-purity zirconium oxide powder with a particle size of 10-20 μm; and the NiAl powder is high-purity NiAl powder with a particle size of 1-20 μm.

[0010] Preferably, the binder is at least one of polyvinyl alcohol, silica sol, and sodium silicate.

[0011] A method for preparing a slurry for tenon protection during aluminizing, comprising the following steps:

[0012] The zircon powder is measured according to the weight ratio of each component of the bottom protective slurry to obtain a bottom protective slurry, and the bottom protective slurry is obtained by uniformly mixing the bottom protective slurry, a binder and deionized water.

[0013] Measure zirconium oxide powder according to the weight ratio of each component of the transition layer protective slurry to obtain a transition layer powder, and mix the transition layer powder, a binder, and deionized water to obtain a transition layer protective slurry;

[0014] Mix zirconia powder and NiAl powder according to the weight ratio of each component of the surface protective slurry, and mix the powders with a stirrer for 30 minutes to obtain a uniformly mixed surface layer powder;

[0015] The surface layer mixed powder, binder and deionized water are uniformly mixed according to the weight ratio of each component of the surface layer protective slurry to obtain the surface layer protective slurry.

[0016] A method for using a slurry for protecting tenons during aluminizing. Before aluminizing, the protective slurry is applied to positions that do not require aluminizing, such as the tenons of blades, to form an impermeable layer to protect the tenons of the blades and prevent the formation of an aluminized layer on the surface during high-temperature aluminizing.

[0017] Preferably, the method comprises the following steps:

[0018] Use a brush to evenly apply the bottom protective slurry to the tenon surface to achieve full coverage of the tenon position and avoid applying it on the blade position, and then dry it;

[0019] Take out the dried blades, and use a brush to evenly apply the transition layer of protective slurry on the surface of the blade tenon coated with the bottom layer of protective slurry to achieve full coverage of the tenon position and avoid coating on the blade position, and then dry;

[0020] Take out the dried blades, and use a brush to evenly apply the surface protective slurry on the surface of the blade tenon coated with the transition layer protective slurry to achieve full coverage of the tenon position and avoid coating on the blade position, and then dry;

[0021] After the blade is dried, a protective slurry can be obtained which can provide effective protection to the tenon position during the aluminizing process and does not react with the substrate.

[0022] Preferably, the bottom layer protective slurry has a thickness of 5-10 mm, the transition layer protective slurry has a thickness of 10-20 mm, and the surface layer protective slurry has a thickness of 10-30 mm; after the aluminizing is completed, it can be removed by lightly tapping with a rubber hammer.

[0023] Preferably, the drying temperature is 70-200° C., and the drying time is 20-60 min.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] (1) The present invention selects materials with similar physical and chemical properties as slurry powder, which has a low thermal expansion coefficient and good bonding and matching between layers;

[0026] (2) The present invention adopts a multi-layer combination of a bottom layer, a transition layer, and a surface layer to form a multifunctional layer at the blade tenon position with good anti-seepage effect and easy removal, providing effective protection for the blade tenon during the aluminizing process;

[0027] (3) The present invention can achieve effective protection of the tenon by preparing a bottom protective layer with high structural strength and no reaction with the matrix, and can provide good structural support for the subsequent transition layer and surface layer anti-seepage layer structure;

[0028] (4) The protective slurry of the present invention has simple ingredients, low cost and is easy to prepare;

[0029] (5) The protective slurry of the present invention has good high-temperature stability and high structural strength. It can maintain a good structure after being infiltrated with aluminum and has strong applicability and can be used on a variety of nickel-based high-temperature alloy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a cross-sectional morphology diagram of the tenon position of the first nickel-based single crystal high-temperature alloy blade after aluminizing and then protective treatment with the slurry of the present invention;

[0031] Figure 2This is a cross-sectional morphology of the blade tenon position of the first nickel-based single crystal high-temperature alloy blade after aluminizing and then using other protection schemes;

[0032] Figure 3 This is a cross-sectional morphology of the blade tenon position of the second type of nickel-based single crystal high-temperature alloy blade after aluminizing and slurry protection treatment;

[0033] Figure 4 This is a cross-sectional morphology of the tenon position of the second type of nickel-based single crystal high-temperature alloy blade after aluminizing and then using other protection schemes. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The invention discloses a slurry for protecting tenons during an aluminizing process, which is composed of the following three layers: a bottom layer protective slurry, a transition layer protective slurry and a surface layer protective slurry; wherein the weight proportions of the components of the bottom layer protective slurry are: 50-80 parts of zircon powder, 10-50 parts of a binder and 1-20 parts of deionized water; the weight proportions of the components of the transition layer protective slurry are: 10-60 parts of zirconium oxide, 10-30 parts of a binder and 1-20 parts of deionized water; and the weight proportions of the components of the surface layer protective slurry are: 10-30 parts of zirconium oxide, 10-40 parts of NiAl powder, 10-30 parts of a binder and 1-20 parts of deionized water.

[0036] Zircon powder is high-purity zircon powder with a particle size of 200-350 mesh;

[0037] Zirconia is high-purity zirconium oxide powder with a particle size of 10-20 μm;

[0038] NiAl powder is high-purity NiAl powder with a particle size of 1-20 μm.

[0039] The binder is at least one of polyvinyl alcohol, silica sol and sodium silicate.

[0040] The present invention also discloses a method for preparing a slurry for protecting tenons during aluminizing, comprising the following steps:

[0041] The zircon powder is measured according to the weight ratio of each component of the bottom protective slurry to obtain a bottom protective slurry, and the bottom protective slurry is obtained by uniformly mixing the bottom protective slurry, a binder and deionized water.

[0042] Measure zirconium oxide powder according to the weight ratio of each component of the transition layer protective slurry to obtain a transition layer powder, and mix the transition layer powder, a binder, and deionized water to obtain a transition layer protective slurry;

[0043] Mix zirconia powder and NiAl powder according to the weight ratio of each component of the surface protective slurry, and mix the powders with a stirrer for 30 minutes to obtain a uniformly mixed surface layer powder;

[0044] The surface layer mixed powder, binder and deionized water are uniformly mixed according to the weight ratio of each component of the surface layer protective slurry to obtain the surface layer protective slurry.

[0045] The present invention also discloses a method for using a slurry for protecting tenons during aluminizing. Before aluminizing, the protective slurry is applied to positions that do not require aluminizing, such as the tenons of blades, to form an impermeable layer to protect the tenons of the blades and prevent the formation of an aluminized layer on the surface during high-temperature aluminizing.

[0046] The following steps are involved:

[0047] Use a brush to evenly apply the bottom protective slurry to the tenon surface to achieve full coverage of the tenon position and avoid applying it on the blade position, and then dry it;

[0048] Take out the dried blades, and use a brush to evenly apply the transition layer of protective slurry on the surface of the blade tenon coated with the bottom layer of protective slurry to achieve full coverage of the tenon position and avoid coating on the blade position, and then dry;

[0049] Take out the dried blades, and use a brush to evenly apply the surface protective slurry on the surface of the blade tenon coated with the transition layer protective slurry to achieve full coverage of the tenon position and avoid coating on the blade position, and then dry;

[0050] After the blade is dried, a protective slurry can be obtained which can provide effective protection to the tenon position during the aluminizing process and does not react with the substrate.

[0051] The thickness of the bottom protective slurry is 5~10mm, the thickness of the transition layer protective slurry is 10~20mm, and the thickness of the surface layer protective slurry is 10~30mm; after the aluminizing is completed, it can be removed by lightly tapping with a rubber hammer.

[0052] The drying temperature is 70-200℃ and the drying time is 20~60min. Example 1

[0053] The tenon of the first nickel-based single crystal high-temperature alloy blade is used as the protection object, and the protective slurry of the present invention is used for aluminizing protection. The specific implementation steps are as follows:

[0054] Step 1: Clean the surface of the blade tenon by ultrasonically cleaning the blade in alcohol and acetone for 20 minutes, and then blow dry for later use;

[0055] Step 2: Prepare mixed powders of the base layer, transition layer, and surface layer according to the proportions. The base layer powder and weight ratio are: 60 parts zircon powder; the transition layer powder and weight ratio are: 50 parts zirconium oxide powder; the surface layer powder and weight ratio are: 20 parts zirconium oxide powder and 30 parts NiAl powder. Mix the surface layer powders in a blender for 30 minutes to obtain a uniformly mixed surface layer powder.

[0056] Step 3: Using polyvinyl alcohol as a binder, 20 parts by weight of polyvinyl alcohol are measured, 15 parts of deionized water are added, and the mixture is mixed evenly at 80° C., and then mixed evenly with the bottom layer powder to obtain a bottom layer protective slurry;

[0057] Step 4: Use a brush to evenly apply the slurry to the tenon of the first nickel-based single crystal high-temperature alloy blade, ensuring that the tenon is completely covered and avoiding coating the blade body. The coating thickness is about 10 mm. The blade is then placed in an oven and baked at 150°C for 40 minutes.

[0058] Step 5: Using polyvinyl alcohol as a binder, 20 parts by weight of polyvinyl alcohol is added to 15 parts of deionized water, mixed evenly at 80° C., and mixed evenly with the transition layer powder to obtain a transition layer protective slurry;

[0059] Step 6: Take out the dried blade coated with the bottom protective slurry, and after cooling, use a brush to apply the transition layer protective slurry, ensuring that the tenon position is completely covered and avoiding the blade body position. The coating thickness is about 15 mm. Then, place the blade in an oven at 100°C for 30 minutes;

[0060] Step 7: Using polyvinyl alcohol as a binder, 20 parts by weight of polyvinyl alcohol is added to 15 parts of deionized water, mixed evenly at 80° C., and mixed evenly with the surface layer powder to obtain a surface layer protective slurry;

[0061] Step 8: Remove the dried blade coated with the transition layer protective slurry, and after cooling, apply the surface protective slurry with a brush, ensuring that the tenon position is completely covered and avoiding coating the blade body position. The coating thickness is about 20 mm. Then, place the blade in an oven at 100°C for 60 minutes; after cooling, an anti-seepage layer is obtained at the tenon position of the blade;

[0062] As a comparison, another blade tenon position was protected by slurry coating using other solutions.

[0063] After the slurry coating was completed, the blade body was wiped clean with alcohol. Then, the first nickel-based single crystal superalloy blade coated with the protective slurry at the tenon position and the control blade were aluminized at 1040°C for 5 hours.

[0064] After aluminizing, the first nickel-based single crystal superalloy blade was taken out and the protective slurry was removed using a rubber hammer and tweezers. It was then ultrasonically treated in alcohol and acetone for 20 minutes respectively and then dried.

[0065] The cross-sectional morphology of the tenon position of the first nickel-based single crystal high-temperature alloy blade protected by this patent was characterized using a scanning electron microscope. The results are as follows: Figure 1 As shown, no obvious diffusion layer was observed at the tenon position of the first nickel-based single crystal high-temperature alloy blade, and the matrix maintained the nickel-based single crystal high-temperature alloy structure, indicating that the tenon was well protected and the protective slurry had a good anti-seepage effect; no slurry residue was found on the surface, indicating that the slurry of the present invention has good removability after high-temperature aluminum infiltration.

[0066] The cross-sectional morphology of the blade tenon position protected by other solutions is as follows Figure 2 As shown in the figure, it can be found that there are many residual slurry particles on the surface of the tenon and the matrix has obvious degradation areas, which shows that the slurry of this patent has obvious anti-seepage effect and excellent performance. Example 2

[0067] The tenon of the second nickel-based single crystal high-temperature alloy blade is used as the protection object, and the protective slurry of the present invention is used for aluminizing protection. The specific implementation steps are as follows:

[0068] Step 1: Clean the surface of the blade tenon by ultrasonically cleaning the blade in alcohol and acetone for 20 minutes, and then blow dry for later use;

[0069] Step 2: Prepare mixed powders of the base layer, transition layer, and surface layer according to the proportions. The base layer powder and weight ratio are: 70 parts zircon powder; the transition layer powder and weight ratio are: 40 parts zirconium oxide powder; the surface layer powder and weight ratio are: 30 parts zirconium oxide powder and 30 parts NiAl powder. Mix the surface layer powders in a blender for 30 minutes to obtain a uniformly mixed surface layer powder.

[0070] Step 3: Using polyvinyl alcohol as a binder, 15 parts by weight of polyvinyl alcohol are measured, 15 parts by weight of deionized water are added, and the mixture is mixed evenly at 80° C., and then mixed evenly with the bottom layer powder to obtain a bottom layer protective slurry;

[0071] Step 4: Use a brush to evenly apply the slurry to the tenon of the second nickel-based single crystal superalloy blade, ensuring that the tenon is completely covered and avoiding coating the blade body. The coating thickness is about 10 mm. The blade is then placed in an oven and baked at 130°C for 50 minutes.

[0072] Step 5: Using silica sol as a binder, 20 parts by weight of silica sol are mixed with the transition layer powder, and 2 parts of deionized water are added and mixed evenly to obtain a transition layer protective slurry;

[0073] Step 6: Take out the dried blade coated with the bottom protective slurry, and after cooling, use a brush to apply the transition layer protective slurry, ensuring that the tenon position is completely covered and avoiding the blade body position. The coating thickness is about 10mm. Then, place the blade in an oven at 100°C for 40 minutes;

[0074] Step 7: Using silica sol as a binder, 20 parts by weight of silica sol are mixed with the surface layer powder, and 2 parts of deionized water are added and mixed evenly to obtain a surface layer protective slurry;

[0075] In step 8, the dried blade coated with the transition layer protective slurry was removed and, after cooling, the surface protective slurry was applied using a brush, ensuring complete coverage of the tenon and avoiding the blade body. The coating thickness was approximately 15 mm. The blade was then oven-dried at 90°C for 40 minutes. After cooling, an impermeable layer was formed at the tenon. For comparison, another blade tenon was protected with slurry using a different method.

[0076] After the slurry coating is completed, the blade body position is wiped clean with alcohol; then, the second nickel-based single crystal high-temperature alloy blade and the comparison blade coated with protective slurry at the tenon position are aluminized at 1020℃ for 5 hours.

[0077] After aluminizing treatment, the second nickel-based single crystal high-temperature alloy blade is taken out, and the protective slurry is removed using a rubber hammer and tweezers. It is then ultrasonically treated in alcohol and acetone for 20 minutes respectively, and then blown dry.

[0078] The cross-sectional morphology of the tenon position of the second nickel-based single crystal high-temperature alloy blade protected by this patent was characterized using a scanning electron microscope. The results are as follows: Figure 3 As shown, no obvious infiltration layer was observed at the tenon of the second nickel-based single crystal superalloy blade, and the substrate maintained the nickel-based single crystal superalloy structure, indicating that the tenon was well protected and the protective slurry had a good anti-seepage effect. No slurry residue was found on the surface, indicating that the protective slurry of the present invention has good removability after high-temperature aluminization.

[0079] The cross-sectional morphology of the blade tenon position protected by other solutions is as follows Figure 4 As shown in the figure, it can be found that there are many residual slurry particles on the surface of the tenon and the matrix has obvious degradation areas. The surface shows that the slurry of this patent has obvious anti-seepage effect and excellent performance.

[0080] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A slurry for tenon protection during aluminizing, characterized in that: It is composed of the following three layers: a bottom protective slurry, a transition layer protective slurry and a surface layer protective slurry; wherein the bottom protective slurry includes: zircon powder, binder, and deionized water; the transition layer protective slurry includes: zirconium oxide, binder, and deionized water; the surface layer protective slurry includes: zirconium oxide, NiAl powder, binder, and deionized water; The weight proportions of the components of the bottom protective slurry are: 50-80 parts of zircon powder, 10-50 parts of binder, and 1-20 parts of deionized water; the weight proportions of the components of the transition layer protective slurry are: 10-60 parts of zirconium oxide, 10-30 parts of binder, and 1-20 parts of deionized water; the weight proportions of the components of the surface layer protective slurry are: 10-30 parts of zirconium oxide, 10-40 parts of NiAl powder, 10-30 parts of binder, and 1-20 parts of deionized water; The method for using the slurry is to apply a protective slurry to the tenon position of the blade where aluminization is not required before aluminizing to form an anti-seepage layer to protect the tenon position of the blade and prevent the formation of an aluminized layer on the surface during the high-temperature aluminizing process; The following steps are involved: Use a brush to evenly apply the bottom protective slurry to the tenon surface to achieve full coverage of the tenon position and avoid applying it on the blade position, and then dry it; Take out the dried blades, and use a brush to evenly apply the transition layer of protective slurry on the surface of the blade tenon coated with the bottom layer of protective slurry to achieve full coverage of the tenon position and avoid coating on the blade position, and then dry; Take out the dried blades and use a brush to evenly apply the surface protective slurry on the surface of the blade tenon coated with the transition layer protective slurry to achieve full coverage of the tenon position and avoid coating on the blade position, and then dry; After the blade is dried, a protective slurry can be obtained which can provide effective protection for the tenon position during the aluminizing process and does not react with the substrate; The coating thickness of the bottom protective slurry is 5-10mm, the coating thickness of the transition layer protective slurry is 10-20mm, and the coating thickness of the surface layer protective slurry is 10-30mm. After the aluminizing is completed, it can be removed by lightly hitting with a rubber hammer; The drying temperature is 70-200° C., and the drying time is 20-60 minutes.

2. The slurry for tenon protection during aluminizing according to claim 1, characterized in that: The zircon powder is high-purity zircon powder with a particle size of 200-350 mesh; the zirconium oxide is high-purity zirconium oxide powder with a particle size of 10-20 μm; and the NiAl powder is high-purity NiAl powder with a particle size of 1-20 μm.

3. The slurry for tenon protection during aluminizing according to claim 1, characterized in that: The binder is at least one of polyvinyl alcohol, silica sol and sodium silicate.

4. The slurry for tenon protection during aluminizing according to claim 1, characterized in that: The following steps are involved: The zircon powder is measured according to the weight ratio of each component of the bottom protective slurry to obtain a bottom protective slurry, and the bottom protective slurry is obtained by uniformly mixing the bottom protective slurry, a binder and deionized water. Measure zirconium oxide powder according to the weight ratio of each component of the transition layer protective slurry to obtain a transition layer powder, and mix the transition layer powder, a binder, and deionized water to obtain a transition layer protective slurry; Mix zirconia powder and NiAl powder according to the weight ratio of each component of the surface protective slurry, and mix the powders with a stirrer for 30 minutes to obtain a uniformly mixed surface layer powder; The surface layer mixed powder, binder and deionized water are uniformly mixed according to the weight ratio of each component of the surface layer protective slurry to obtain the surface layer protective slurry.

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