Preparation method of coating of ceramic core for directional solidification heavy gas turbine blade

Abstract

The invention relates to the technical field of high-temperature coatings, and discloses a preparation method of a coating of a ceramic core for a directionally solidified heavy gas turbine blade, which comprises the following steps: preparing powder: preparing chromic oxide, basic aluminum silicate and boric acid; mixing the powder materials; preparing a coating: soaking the mixed powder in aluminum sol, and uniformly stirring to obtain soaked powder; adding deionized water and a wetting agent into a stirring barrel, and stirring at a high speed to obtain an aqueous solution; adding the soaked powder into the aqueous solution for multiple times, and uniformly stirring to obtain a coating; high-pressure atomization spraying is adopted, natural air drying or ammonia drying treatment is carried out after spraying, and resin liquid is used for curing treatment; and high-temperature roasting is conducted, specifically, the cured coating is subjected to high-temperature roasting, and the final coating is obtained. According to the preparation method of the coating of the ceramic core for the directional solidification heavy-duty gas turbine blade, the coating containing the chromium oxide component can be formed on the surface of the ceramic core.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature coatings, and in particular provides a method for preparing a coating of a directionally solidified ceramic core for a heavy-duty combustion engine blade. Background Art

[0002] For the directionally solidified ceramic cores for heavy-duty gas turbine blades, due to the characteristics of the casting process and the large size of the heavy-duty gas turbine ceramic cores themselves, heavy-duty gas turbine blades will have casting pores, shrinkage holes, shrinkage and other problems. The high-temperature coatings such as alumina and zirconia of the ceramic cores are easy to fall off during the shell baking process. In order to cope with the process characteristics of directional solidification, how to improve the quality and performance of the ceramic cores and effectively improve their high-temperature stability, high-temperature impact resistance and high-temperature strength has become an urgent problem to be solved. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a method for preparing a coating of a directionally solidified ceramic core for heavy-duty gas turbine blades, so as to solve the problems existing in the prior art.

[0004] The present invention provides a method for preparing a coating of a directionally solidified ceramic core for a heavy-duty gas turbine blade, comprising:

[0005] Prepare powder: prepare chromium oxide, basic aluminum silicate, and boric acid according to mass percentage (20% to 35%): (5% to 10%): (3% to 5%);

[0006] Mixed powder: put the powder into a ball mill, add deionized water, and ball mill to obtain slurry. Then, take out the obtained slurry, sieve it, dry it, and seal it for storage;

[0007] Preparation of coating: soaking the mixed powder in aluminum sol and stirring evenly to obtain soaked powder, wherein the mass of the aluminum sol accounts for 50% to 65% of the mass of the soaked powder; adding deionized water and a wetting agent into a stirring barrel and stirring at high speed to obtain an aqueous solution, wherein the mass of the deionized water is 28% to 32% of the mass of the mixed powder, and the volume of the wetting agent is 0.3% to 0.6% of the volume of the deionized water; adding the soaked powder into the aqueous solution in multiple times and stirring evenly to obtain coating;

[0008] Spray curing: Use high-pressure atomization spraying, air dry naturally or use ammonia drying treatment after spraying, and use resin liquid to cure it to obtain the coating;

[0009] High temperature baking: The cured coating is baked at high temperature to obtain the final coating.

[0010] Preferably, the chromium oxide is cubic chromium oxide, and the structure is a spinel structure.

[0011] Further preferably, the volume ratio of the medium balls to the powder in the ball mill is 1:2-3;

[0012] The mass ratio of deionized water to the material in the ball mill is 1:2-3;

[0013] The ball milling time is 3 to 5 hours;

[0014] The slurry was passed through a 200-mesh sieve and dried at 120°C.

[0015] More preferably, after the soaking powder is added to the aqueous solution, stirring is continued at 1200 rpm for at least 12 hours.

[0016] More preferably, the aluminum sol contains Al 2 O 3 The mass fraction is 20%.

[0017] More preferably, the wetting agent is at least one of sodium dodecyl sulfate, 160,000 trimethylammonium bromide, ammonium octanol phosphate, sodium succinate sulfonate, polyoxyethylene alkyl alcohol or condensate of alkylphenol and ethylene oxide.

[0018] Further preferably, during the spraying process, the coating temperature is controlled at 35°C to 40°C, the spraying environment temperature is 23°C to 27°C, the humidity is 50% to 70%, and ventilation or ammonia drying treatment is performed immediately after spraying.

[0019] More preferably, the spray curing process further includes: drying the coating at 200° C. to 240° C. for secondary curing.

[0020] More preferably, the high temperature calcination temperature is 1460°C to 1540°C.

[0021] In the coating preparation method for a ceramic core for a directional solidification heavy-duty gas turbine blade provided by the present invention, the coating is mainly composed of an aluminum borosilicate system, and high-stability chromium oxide is added, and is coated on the surface of the ceramic core through a sol. Thereafter, it can be effectively solidified on the surface of the ceramic core through high-temperature roasting, so that a coating containing chromium oxide components is formed on the surface of the ceramic core, which can increase the high-temperature impact resistance and chemical stability of the ceramic core, and solve the problems of casting pores, shrinkage cavities, shrinkage porosity, etc. of directional solidification heavy-duty gas turbine blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described in detail below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 X-RD diagram of the final coating obtained in Example 1;

[0024] Figure 2 This is an electron microscope analysis of the final coating obtained in Example 1. DETAILED DESCRIPTION

[0025] The present invention will be further explained below in conjunction with specific implementation schemes, but the present invention is not limited thereto.

[0026] In order to increase the high temperature impact resistance and chemical stability of the ceramic core and solve the problems of pores, shrinkage holes, shrinkage and porosity in the casting of directional solidification heavy-duty gas turbine blades, the present invention provides a coating preparation method for a ceramic core for directional solidification heavy-duty gas turbine blades, comprising the following steps:

[0027] Prepare powder: prepare chromium oxide, basic aluminum silicate, and boric acid according to the mass percentage (20% to 35%): (5% to 10%): (3% to 5%); preferably, chromium oxide uses a cubic crystal system with a spinel structure, which has higher stability and higher hardness, and can be better combined in the aluminum borosilicate system through subsequent treatment;

[0028] Mixed powder: put the powder into a ball mill, add deionized water, and ball mill to obtain slurry. Then, take out the obtained slurry, sieve it, dry it, and seal it for storage;

[0029] Preferably, the volume ratio of the medium balls to the powder in the ball mill is 1:2-3;

[0030] The mass ratio of deionized water to the material in the ball mill is 1:2-3;

[0031] The ball milling time is 3 to 5 hours;

[0032] The slurry was passed through a 200-mesh sieve and dried at 120°C;

[0033] Preparation of coating: soaking the mixed powder in aluminum sol and stirring evenly to obtain soaked powder, wherein the mass of the aluminum sol accounts for 50% to 65% of the mass of the soaked powder; adding deionized water and a wetting agent into a stirring barrel and stirring at high speed to obtain an aqueous solution, wherein the mass of the deionized water is 28% to 32% of the mass of the mixed powder, and the volume of the wetting agent is 0.3% to 0.6% of the volume of the deionized water; adding the soaked powder into the aqueous solution in multiple times and stirring evenly to obtain coating; preferably, after the soaked powder is added to the aqueous solution, stirring is continued at 1200 rpm for at least 12 hours;

[0034] Preferably, the aluminum sol contains Al 2 O 3 The mass fraction is 20%.

[0035] Wherein, the wetting agent is at least one of sodium dodecyl sulfonate, 160,000 trimethyl ammonium bromide, ammonium octanol phosphate, sodium succinate sulfonate, polyoxyethylene alkyl alcohol or condensate of alkylphenol and ethylene oxide;

[0036] Spray curing: Use high-pressure atomization spraying, air dry naturally or use ammonia drying treatment after spraying, and use resin liquid to cure it to obtain the coating;

[0037] Preferably, during the spraying process, the coating temperature is controlled at 35°C to 40°C, the spraying environment temperature is 23°C to 27°C, the humidity is 50% to 70%, and ventilation or ammonia drying treatment is performed immediately after spraying.

[0038] More preferably, the spray curing process further includes: drying the coating at 200° C. to 240° C. for secondary curing.

[0039] High temperature calcination: The cured coating is calcined at high temperature to obtain a final coating. Preferably, the high temperature calcination temperature is 1460°C to 1540°C.

[0040] In the preparation method of the coating of the directionally solidified ceramic core for heavy-duty gas turbine blades, the coating is mainly composed of an aluminum borosilicate system, and high-stability chromium oxide is added. The coating is coated on the surface of the ceramic core through sol, and can be effectively solidified on the surface of the ceramic core after high-temperature calcination, so that a coating containing chromium oxide components is formed on the surface of the ceramic core, which effectively improves the high-temperature stability, high-temperature impact resistance and high-temperature strength of the ceramic core.

[0041] Example 1

[0042] The steps for preparing the coating of the directionally solidified ceramic core for heavy-duty gas turbine blades are as follows:

[0043] Prepare powder: prepare 30% chromium oxide, 5% basic aluminum silicate, and 5% boric acid by mass percentage, wherein the total mass of chromium oxide, basic aluminum silicate, and boric acid accounts for 40% of the total mass fraction of aluminum sol, chromium oxide, basic aluminum silicate, and boric acid, and the chromium oxide uses a cubic crystal system and has a spinel structure;

[0044] Mixing powder: putting the powder into a ball mill, adding deionized water, ball milling to obtain slurry, then taking out the obtained slurry, sieving it, drying it and sealing it for storage, wherein the volume ratio of the medium balls in the ball mill to the powder is 1:2.5, the mass ratio of deionized water to the material in the ball mill is 1:2, the ball milling time is 4 hours, and the slurry is sieved with a 200 mesh sieve and dried at 120°C;

[0045] Preparation of coating: soaking the mixed powder in aluminum sol [w(Al2O3)=20%] and stirring evenly to obtain soaked powder, wherein the mass of the aluminum sol accounts for 60% of the mass of the soaked powder, that is, the total mass fraction of aluminum sol, chromium oxide, basic aluminum silicate, and boric acid is 100%; adding deionized water and a wetting agent into a stirring barrel and stirring at high speed to obtain an aqueous solution, wherein the mass of the deionized water is 30% of the mass of the mixed powder, and the volume of the wetting agent is 0.5% of the volume of the deionized water; adding the soaked powder into the aqueous solution several times and stirring evenly to obtain coating, wherein after the soaked powder is added to the aqueous solution, stirring is continued at 1200rpm for at least 12 hours;

[0046] Spraying and curing: high-pressure atomization spraying is adopted. During the spraying process, the coating temperature is ensured to be 38°C, the spraying environment temperature is 23°C to 27°C, and the humidity is 50-70%. After spraying, it is naturally air-dried, and then cured with resin liquid, and then dried at 200°C for secondary curing;

[0047] High temperature calcination: The cured coating is calcined at high temperature to obtain a final coating, wherein the high temperature calcination temperature is 1520°C.

[0048] The composition of the coating surface material finally obtained was analyzed and it was determined that the composition contained chromium oxide, among which: Figure 1 The X-RD diagram of the final coating was compared with the standard database card to determine that the phase contained high-stability chromium oxide. Figure 2 This is an electron microscope analysis of the final coating. Through high-resolution imaging and analysis of the sample, it was determined that the crystal structure contains aluminum, silicon and chromium oxide.

[0049] Example 2

[0050] The steps for preparing the coating of the directionally solidified ceramic core for heavy-duty gas turbine blades are as follows:

[0051] Prepare powder: prepare 25% chromium oxide, 5% basic aluminum silicate, and 5% boric acid by mass percentage, wherein the total mass of chromium oxide, basic aluminum silicate, and boric acid accounts for 35% of the total mass fraction of aluminum sol, chromium oxide, basic aluminum silicate, and boric acid;

[0052] Mixed powder: put the powder into a ball mill, add deionized water, and ball mill to obtain slurry. Then, take out the obtained slurry, sieve it, dry it, and seal it for storage. The volume ratio of the medium balls in the ball mill to the powder is 1:3, the mass ratio of deionized water to the material in the ball mill is 1:2.5, the ball milling time is 5 hours, and the slurry is sieved with 200 mesh and dried at 120°C.

[0053] Preparation of coating: soaking the mixed powder in aluminum sol [w(Al2O3)=20%] and stirring evenly to obtain soaked powder, wherein the mass of the aluminum sol accounts for 65% of the mass of the soaked powder, that is, the total mass fraction of aluminum sol, chromium oxide, basic aluminum silicate, and boric acid is 100%; adding deionized water and a wetting agent into a stirring barrel and stirring at high speed to obtain an aqueous solution, wherein the mass of the deionized water is 32% of the mass of the mixed powder, and the volume of the wetting agent is 0.3% of the volume of the deionized water; adding the soaked powder into the aqueous solution several times and stirring evenly to obtain coating, wherein after the soaked powder is added to the aqueous solution, stirring is continued at 1200rpm for at least 12 hours;

[0054] Spraying and curing: high-pressure atomization spraying is adopted. During the spraying process, the coating temperature is ensured to be 35°C, the spraying environment temperature is 23°C to 27°C, and the humidity is 50-70%. After spraying, it is naturally air-dried, and then cured with resin liquid. After that, it is dried at 220°C for secondary curing;

[0055] High temperature calcination: The cured coating is calcined at high temperature to obtain the final coating, wherein the temperature of the high temperature calcination is 1540° C. The composition of the surface material of the final coating is analyzed to determine that the composition contains chromium oxide.

[0056] Example 3

[0057] The steps for preparing the coating of the directionally solidified ceramic core for heavy-duty gas turbine blades are as follows:

[0058] Prepare powder: prepare 35% chromium oxide, 10% basic aluminum silicate, and 5% boric acid by mass percentage, wherein the total mass of chromium oxide, basic aluminum silicate, and boric acid accounts for 50% of the total mass fraction of aluminum sol, chromium oxide, basic aluminum silicate, and boric acid, and the chromium oxide uses a cubic crystal system and has a spinel structure;

[0059] Mixing powder: putting the powder into a ball mill, adding deionized water, ball milling to obtain slurry, then taking out the obtained slurry, sieving it, drying it and sealing it for storage, wherein the volume ratio of the medium balls in the ball mill to the powder is 1:2, the mass ratio of deionized water to the material in the ball mill is 1:3, the ball milling time is 3 hours, the slurry is sieved with 200 mesh and dried at 120°C;

[0060] Preparation of coating: soaking the mixed powder in aluminum sol [w(Al2O3)=20%] and stirring evenly to obtain soaked powder, wherein the mass of the aluminum sol accounts for 50% of the mass of the soaked powder, that is, the total mass fraction of aluminum sol, chromium oxide, basic aluminum silicate, and boric acid is 100%; adding deionized water and a wetting agent into a stirring barrel and stirring at high speed to obtain an aqueous solution, wherein the mass of the deionized water is 28 of the mass of the mixed powder, and the volume of the wetting agent is 0.6% of the volume of the deionized water; adding the soaked powder into the aqueous solution several times and stirring evenly to obtain coating, wherein after the soaked powder is added to the aqueous solution, stirring is continued at 1200rpm for at least 12 hours;

[0061] Spraying and curing: high-pressure atomization spraying is adopted. During the spraying process, the coating temperature is ensured to be 40°C, the spraying environment temperature is 23°C to 27°C, and the humidity is 50-70%. After spraying, it is naturally air-dried, and then cured with resin liquid, and then dried at 240°C for secondary curing;

[0062] High temperature calcination: The cured coating is calcined at high temperature to obtain the final coating, wherein the temperature of the high temperature calcination is 1460° C. The composition of the surface material of the final coating is analyzed to determine that chromium oxide is contained in the composition.

[0063] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing a coating of a directional solidified ceramic core for a heavy-duty gas turbine blade, characterized in that: include: Prepare powder: prepare chromium oxide, basic aluminum silicate, and boric acid according to mass percentage (20% to 35%): (5% to 10%): (3% to 5%); Mixed powder: put the powder into a ball mill, add deionized water, and ball mill to obtain slurry. Then, take out the obtained slurry, sieve it, dry it, and seal it for storage; Preparation of coating: soaking the mixed powder in aluminum sol and stirring evenly to obtain soaked powder, wherein the mass of the aluminum sol accounts for 50% to 65% of the mass of the soaked powder; adding deionized water and a wetting agent into a stirring barrel and stirring at high speed to obtain an aqueous solution, wherein the mass of the deionized water is 28% to 32% of the mass of the mixed powder, and the volume of the wetting agent is 0.3% to 0.6% of the volume of the deionized water; adding the soaked powder into the aqueous solution in multiple times and stirring evenly to obtain coating; Spray curing: Use high-pressure atomization spraying, air dry naturally or use ammonia drying treatment after spraying, and use resin liquid to cure it to obtain the coating; High temperature baking: The cured coating is baked at high temperature to obtain the final coating.

2. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: The chromium oxide is cubic chromium oxide, and its structure is spinel structure.

3. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: The volume ratio of the medium balls to the powder in the ball mill is 1:2-3; The mass ratio of deionized water to the material in the ball mill is 1:2-3; The ball milling time is 3 to 5 hours; The slurry was passed through a 200-mesh sieve and dried at 120°C.

4. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: After the soaking powder is added to the aqueous solution, stirring is continued at 1200 rpm for at least 12 hours.

5. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: The mass fraction of Al2O3 in the aluminum sol is 20%.

6. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: The wetting agent is at least one of sodium dodecyl sulfonate, 160,000 trimethyl ammonium bromide, ammonium octanol phosphate, sodium succinate sulfonate, polyoxyethylene alkyl alcohol or condensate of alkylphenol and ethylene oxide.

7. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: During the spraying process, the temperature of the coating is controlled at 35°C to 40°C, the spraying environment temperature is 23°C to 27°C, the humidity is 50% to 70%, and ventilation or ammonia drying treatment is performed immediately after spraying.

8. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: The spray curing process also includes: drying the coating at 200°C to 240°C for secondary curing.

9. The method for preparing coating of directionally solidified ceramic core for heavy-duty combustion engine blades according to claim 1, characterized in that: The temperature of high temperature calcination is 1460℃~1540℃.

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