Thermal barrier coating resistant to volcanic ash corrosion as well as preparation method and application of thermal barrier coating

Abstract

The invention relates to the technical field of protection, in particular to a volcanic ash corrosion resistant thermal barrier coating and a preparation method and application thereof. The preparation method of the thermal barrier coating resistant to volcanic ash corrosion comprises the following steps that S1, rare earth oxide and tantalum pentoxide are subjected to ball milling and mixing, and a mixture is obtained; s2, drying the mixture, sieving, and pressing to obtain a green body; and S3, the blank is calcined and then cooled, and the volcanic ash corrosion resistant thermal barrier coating is prepared. The volcanic ash corrosion resistant thermal barrier coating powder prepared through the method is high in purity, high in density and excellent in volcanic ash type CMAS corrosion resistant effect, and can work for a long time in high-temperature and complex chemical environment scenes such as engines and turbines without being damaged.

Description

Technical Field

[0001] The present application relates to the field of protection technology, and in particular to a volcanic ash corrosion resistant thermal barrier coating and a preparation method and application thereof. Background Art

[0002] Thermal barrier coatings (TBCs, thermal barrier coatings) refer to a "laminated" metal-ceramic composite coating system composed of a metal bonding layer and a ceramic oxide surface layer with excellent heat resistance and thermal insulation. Thermal barrier coatings have good thermal insulation effects, high hardness, and excellent chemical stability. They are mainly used to reduce the operating temperature of the substrate to prevent the substrate from high-temperature oxidation, corrosion, and wear, so that the devices made of them (such as engine turbine blades) can operate at high temperatures, thereby extending the service life of hot end components, improving efficiency, reducing fuel consumption, and greatly improving thermal engine performance. Thermal barrier coatings are widely used in the hot end components of aircraft engines and gas turbines.

[0003] Thermal barrier coatings have a harsh working environment, demanding service conditions, and complex failure mechanisms. The research and development of long-life thermal barrier coatings is a long way to go. High-temperature service environments can cause the Y2O3 partially stabilized ZrO2 (yttria partially stabilized zirconia, YSZ) coating to decompose into a metastable tetragonal phase (t′), which then transforms into a monoclinic phase (m) during the subsequent cooling process, accompanied by a 3%-4% volume expansion, causing the coating to crack. High temperatures can also accelerate the calcination of the coating, destroy the microstructure of the coating, reduce porosity, and reduce the thermal insulation performance and strain tolerance of the coating. In addition, due to oxidation, thermally grown oxides (TGO) will be generated between the metal bonding layer and the ceramic oxide surface layer. If the thermally grown oxide grows too thick, its coefficient of thermal expansion (CT) will mismatch with the ceramic oxide surface layer, resulting in large internal stress, which will accelerate the coating's spalling failure.

[0004] In addition to the above failure mechanisms, high-temperature corrosion is also an important cause of thermal barrier coating failure. In the actual working conditions of aircraft, the engine will ingest a large amount of sand, dust, volcanic ash, runway debris and various environmental pollutants. These inhaled materials adhere to the hot end components of the engine (such as turbine blades, combustion chamber walls, etc.) at high temperatures. Studies have found that the components of the deposits are mainly CaO, MgO, Al2O3 and SiO2, referred to as CMAS. The melting point of CMAS varies with the composition, but generally speaking, when the operating temperature exceeds 1200°C, CMAS begins to melt, and the high-temperature melt will penetrate along the microcracks and pores in the thermal barrier coating on the surface of the hot end components (such as blades), and react with the coating components, causing the coating phase composition and microstructure to be destroyed, accelerating the failure of the coating, and making the blade alloy face the high-temperature combustion gas directly, which will damage the engine performance. In addition, CMAS will also block the cooling channels of the hot end components (such as blades), causing local overburning.

[0005] CMAS corrosion is the most complex factor in the failure of thermal barrier coatings, and its harm to thermal barrier coatings cannot be underestimated. Volcanic ash is one of the important sources of CMAS and a special type of CMAS that can cause significant damage to thermal barrier coatings. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a volcanic ash corrosion resistant thermal barrier coating and a preparation method and application thereof to solve the volcanic ash type CMAS corrosion problem.

[0007] To achieve the above objectives, the scheme of this application is as follows: In a first aspect, the present invention provides a method for preparing a volcanic ash corrosion resistant thermal barrier coating, comprising the following steps: S1. ball-milling and mixing rare earth oxide and tantalum pentoxide (Ta2O5) to obtain a mixture; S2. drying the mixture, sieving and pressing to obtain a green body; S3. The green body is calcined and then cooled to obtain the volcanic ash corrosion resistant thermal barrier coating.

[0008] Optionally, in step S1, the rare earth oxide is selected from at least one of Y2O3, La2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3 and Lu2O3.

[0009] Optionally, in step S1, the particle size of the rare earth oxide is less than or equal to 10 µm.

[0010] Optionally, in step S1, the molar ratio of the rare earth oxide to the tantalum pentoxide is 0.9-1.1:0.9-1.1, preferably 0.95-1.1:0.95-1.1.

[0011] Optionally, in the ball milling process of step S1, the ball milling medium used is liquid alcohol.

[0012] Optionally, during the ball milling process in step S1, the material ratio of the sum of the rare earth oxide and tantalum pentoxide to the ball milling medium used is 0.8-1.2 g: 0.4-0.7 mL, preferably 0.9-1.2 g: 0.5-0.7 mL.

[0013] Optionally, in step S1, the rotation speed of the ball mill is 300-400 rpm / min, preferably 300-400 rpm / min; the duration of the ball milling is 12-24 h, preferably 18-24 h.

[0014] Optionally, in step S2, the drying temperature is 60-80°C, preferably 65-80°C; the drying time is 12-24h, preferably 18-24h.

[0015] Optionally, in step S2, the product is sieved through a 200-325 mesh sieve, preferably, sieved through a 250-325 mesh sieve.

[0016] Optionally, in step S2, the pressing pressure is 5-10 MPa, preferably 6-10 MPa; the pressing time is 5-10 min, preferably 6-10 min.

[0017] Optionally, in step S3, the calcination temperature is 1400-1700° C., preferably 1500-1700° C.; the calcination time is 6-10 h, preferably 7-10 h.

[0018] In a second aspect, the present invention also provides a volcanic ash corrosion resistant thermal barrier coating prepared according to the method as described above.

[0019] In a third aspect, the present invention also provides the use of the volcanic ash corrosion resistant thermal barrier coating prepared according to the method as described above in hot end components.

[0020] Beneficial effects of the present invention: The volcanic ash corrosion resistant thermal barrier coating crystals prepared by the method of the present application have a single-phase structure without the generation of impurity phases.

[0021] The volcanic ash corrosion resistant thermal barrier coating powder prepared by the method of the present application has high purity and high density.

[0022] The volcanic ash corrosion-resistant thermal barrier coating prepared by the method of the present application has excellent resistance to volcanic ash-type CMAS corrosion and can work for a long time without being damaged in high-temperature and chemically complex environments such as engines and turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 This is a graph showing the relationship between the insulation time and the grain size of the thermal barrier coating against volcanic ash corrosion in Example 6; Figure 2 The X-ray diffraction pattern (XRD pattern) of the volcanic ash corrosion resistant thermal barrier coating prepared in Example 1-4, the abscissa is the 2θ angle, and the ordinate is the intensity; Figure 3 This is the SEM spectrum obtained during the CMAS resistance detection process of the volcanic ash corrosion resistant thermal barrier coating prepared in Example 5. DETAILED DESCRIPTION

[0025] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0026] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0027] An embodiment of the present invention provides a method for preparing a thermal barrier coating resistant to volcanic ash corrosion, comprising the following steps: S1. The rare earth oxide and tantalum pentoxide are ball-milled at a molar ratio of 0.9-1.1:0.9-1.1 at a speed of 300-400 rpm / min for 12-24 hours to obtain a mixture; The particle size of the rare earth oxide is less than or equal to 10 μm, and the rare earth oxide is selected from at least one of Y2O3, La2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3 and Lu2O3; During the ball milling process, the material ratio of the sum of the rare earth oxide and tantalum pentoxide to the ball milling medium used is 0.8-1.2 g: 0.4-0.7 mL, and the ball milling medium is liquid alcohol; S2. Dry the mixture at 60-80 ° C for 12-24h, pass through a 200-325 mesh sieve, and press at a pressure of 5-10 MPa for 5-10min to obtain a green body; S3. calcining the green body at 1400-1700°C for 6-10 hours, and then cooling it to obtain a thermal barrier coating resistant to volcanic ash corrosion.

[0028] Another embodiment of the present invention also provides a volcanic ash corrosion resistant thermal barrier coating prepared according to the method as described above.

[0029] Another embodiment of the present invention also provides the use of the volcanic ash corrosion resistant thermal barrier coating prepared according to the method as described above in hot end components.

[0030] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present invention; however, it is apparent to one skilled in the art that embodiments of the present invention may be practiced without these specific details.

[0031] Example 1 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide Dy2O3 (particle size of 6 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 1 g: 0.6 mL), and ball mill in a planetary ball mill for 24 h (rotation speed is 300 rpm / min) to obtain a mixture; S2. The mixture was dried at 70 ° C for 24 h, passed through a 300 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm and pressed at a pressure of 6 MPa for 5 min to obtain a green body with a diameter of 15 mm and a thickness of 2 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1500° C. for 6 hours to perform a high-temperature solid-phase reaction, and then cooled to room temperature to obtain a thermal barrier coating that is resistant to volcanic ash corrosion.

[0032] The density of the volcanic ash corrosion resistant thermal barrier coating prepared in this embodiment is tested, and the specific steps are as follows: Place the sample to be tested on a balance and weigh the dry weight , wet weight , hanging weight , query and calculate the theoretical density , and the density is calculated according to the following formula: .

[0033] After testing, the density of the volcanic ash corrosion resistant thermal barrier coating prepared in this embodiment is 95%.

[0034] Example 2 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide Gd2O3 (particle size of 6 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 1 g: 0.6 mL), and ball mill for 24 h in a planetary ball mill (rotation speed is 300 rpm / min) to obtain a mixture; S2. The mixture was dried at 70 ° C for 24 h, passed through a 300 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm and pressed at a pressure of 6 MPa for 5 min to obtain a green body with a diameter of 15 mm and a thickness of 2 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1500° C. for 6 hours to perform a high-temperature solid-phase reaction, and then cooled to room temperature to obtain a thermal barrier coating resistant to volcanic ash corrosion.

[0035] The density of the volcanic ash corrosion resistant thermal barrier coating prepared in this example was tested in the same manner as in Example 1.

[0036] According to testing, the density of the volcanic ash corrosion resistant thermal barrier coating prepared in this embodiment is 97%.

[0037] Example 3 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide Yb2O3 (particle size of 6 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 1 g: 0.6 mL), and ball mill in a planetary ball mill for 24 h (rotation speed is 300 rpm / min) to obtain a mixture; S2. The mixture was dried at 70 ° C for 24 h, passed through a 300 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm and pressed at a pressure of 6 MPa for 5 min to obtain a green body with a diameter of 15 mm and a thickness of 2 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1500° C. for 6 hours to perform a high-temperature solid-phase reaction, and then cooled to room temperature to obtain a thermal barrier coating resistant to volcanic ash corrosion.

[0038] The density of the volcanic ash corrosion resistant thermal barrier coating prepared in this example was tested in the same manner as in Example 1.

[0039] After testing, the density of the volcanic ash corrosion resistant thermal barrier coating prepared in this embodiment is 95%.

[0040] Example 4 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide Er2O3 (particle size of 6 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 1 g: 0.6 mL), and ball mill in a planetary ball mill for 24 h (rotation speed is 300 rpm / min) to obtain a mixture; S2. The mixture was dried at 70 ° C for 24 h, passed through a 300 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm and pressed at a pressure of 6 MPa for 5 min to obtain a green body with a diameter of 15 mm and a thickness of 2 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1500° C. for 6 hours to perform a high-temperature solid-phase reaction, and then cooled to room temperature to obtain a thermal barrier coating resistant to volcanic ash corrosion.

[0041] The density of the volcanic ash corrosion resistant thermal barrier coating prepared in this example was tested in the same manner as in Example 1.

[0042] After testing, the density of the volcanic ash corrosion resistant thermal barrier coating prepared in this embodiment is 98%.

[0043] Example 5 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide Y2O3 (particle size of 6 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 1 g: 0.6 mL), and ball mill in a planetary ball mill for 24 h (rotation speed is 300 rpm / min) to obtain a mixture; S2. The mixture was dried at 70 ° C for 24 h, passed through a 300 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm and pressed at a pressure of 6 MPa for 5 min to obtain a green body with a diameter of 15 mm and a thickness of 2 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1500° C. for 6 hours to perform a high-temperature solid-phase reaction, and then cooled to room temperature to obtain a thermal barrier coating that is resistant to volcanic ash corrosion.

[0044] The density of the volcanic ash corrosion resistant thermal barrier coating prepared in this example was tested in the same manner as in Example 1.

[0045] After testing, the density of the volcanic ash corrosion resistant thermal barrier coating prepared in this embodiment is 96%.

[0046] Example 6 The holding time in step S3 of Example 5 was adjusted to 4 h, 5 h, 6 h, 7 h and 8 h respectively, and the grain sizes of the prepared volcanic ash corrosion resistant thermal barrier coatings were detected. The results are as follows: Figure 1 shown.

[0047] Depend on Figure 1 It can be seen that within the range of 4-8h, as the insulation time increases, the grain size of the prepared volcanic ash corrosion resistant thermal barrier coatings shows an upward trend.

[0048] Example 7 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide La2O3 (particle size of 10 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 0.8 g: 0.4 mL), and ball mill for 12 h in a planetary ball mill (rotation speed is 400 rpm / min) to obtain a mixture; S2. The mixture was dried at 60 ° C for 20 h, passed through a 200 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm, and pressed at a pressure of 5 MPa for 10 min to obtain a green body with a diameter of 15 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1400° C. for 10 hours to perform a high-temperature solid-phase reaction, and then cooled to room temperature to obtain a thermal barrier coating resistant to volcanic ash corrosion.

[0049] Example 8 A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, the specific steps are as follows: S1. Weigh 150 g of raw materials of rare earth oxide La2O3 (particle size of 5 μm) and tantalum pentoxide Ta2O5 in a molar ratio of 1:1, pour the weighed raw materials into a ball mill, use anhydrous ethanol as a ball milling medium (the material ratio of the weighed raw materials to the ball milling medium is 1.2 g: 0.7 mL), and ball mill for 18 h in a planetary ball mill (rotation speed is 350 rpm / min) to obtain a mixture; S2. The mixture was dried at 80 ° C for 12 h, passed through a 325 mesh sieve, and the undersize material was loaded into a stainless steel mold with a diameter of 15 mm, and pressed at a pressure of 10 MPa for 5 min to obtain a green body with a diameter of 15 mm; S3. The green body is placed in a high-temperature furnace and calcined at 1700°C for 8 hours to carry out a high-temperature solid phase reaction, and then cooled to room temperature to obtain a thermal barrier coating resistant to volcanic ash corrosion.

[0050] Performance Testing X-ray diffraction (XRD) was performed on the volcanic ash corrosion resistant thermal barrier coatings prepared in Examples 1-4. The results are as follows: Figure 2 shown.

[0051] Depend on Figure 2 It can be seen that the volcanic ash corrosion resistant thermal barrier coatings prepared in Examples 1 to 4 have no second phase diffraction peaks. This result shows that the volcanic ash corrosion resistant thermal barrier coating crystals of the present application have a single-phase structure without the generation of impurity phases.

[0052] The volcanic ash corrosion resistant thermal barrier coating prepared in Example 5 was subjected to CMAS resistance test, and the specific steps were as follows: The four raw materials of CaO, MgO, Al2O3 and SiO2 were mixed in a ball mill in a mass ratio of 33:9:6.5:45, and after ball milling, they were placed in a drying oven at 70°C for 24 hours, and then heat treated at 1300°C for 3 hours. After quenching in water, CMAS blocks were obtained, which were ground in a mortar and passed through a 300-mesh sieve to obtain volcanic ash-type CMAS powder. The CMAS powder was coated on the volcanic ash corrosion resistant thermal barrier coating prepared in Example 5, and subjected to thermal corrosion treatment at 1300°C for 12 h. The coating morphology was observed using a scanning electron microscope. The results are as follows: Figure 3 shown.

[0053] Depend on Figure 3 It can be seen that the volcanic ash corrosion resistant thermal barrier coating prepared in Example 5 was not corroded. The same method was used to perform anti-CMAS detection on the volcanic ash corrosion resistant thermal barrier coatings prepared in Examples 1-4. After detection, the volcanic ash corrosion resistant thermal barrier coatings prepared in Examples 1-4 were not corroded. This result shows that the volcanic ash corrosion resistant thermal barrier coating of the present application has excellent anti-volcanic ash type CMAS corrosion effect.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a thermal barrier coating resistant to volcanic ash corrosion, characterized in that: The following steps are involved: S1. The rare earth oxide and tantalum pentoxide are ball-milled to obtain a mixture; S2. Drying the mixture, sieving and pressing to obtain a green body; S3. The green body is calcined and then cooled to obtain the volcanic ash corrosion resistant thermal barrier coating.

2. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In step S1, the rare earth oxide is selected from at least one of Y2O3, La2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3 and Lu2O3; And / or, in step S1, the particle size of the rare earth oxide is less than or equal to 10 μm.

3. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In step S1, the molar ratio of the rare earth oxide to the tantalum pentoxide is 0.9-1.1:0.9-1.

1.

4. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In the ball milling process of step S1, the ball milling medium used is liquid alcohol; And / or, during the ball milling process in step S1, the material ratio of the sum of the rare earth oxide and tantalum pentoxide to the ball milling medium used is 0.8-1.2 g: 0.4-0.7 mL.

5. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In step S1, the rotation speed of the ball mill is 300-400 rpm / min, and the duration of the ball mill is 12-24 hours.

6. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In step S2, the drying temperature is 60-80°C, and the drying time is 12-24h; And / or, in step S2, passing through a 200-325 mesh sieve.

7. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In step S2, the pressing pressure is 5-10 MPa, and the pressing time is 5-10 min.

8. The method for preparing the volcanic ash corrosion resistant thermal barrier coating according to claim 1, characterized in that: In step S3, the calcination temperature is 1400-1700° C., and the calcination time is 6-10 h.

9. A volcanic ash corrosion resistant thermal barrier coating prepared according to the method according to any one of claims 1 to 8.

10. Use of the volcanic ash corrosion resistant thermal barrier coating prepared according to the method according to any one of claims 1 to 8 in hot end components.

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