Method for synchronously improving CMAS corrosion resistance and thermal shock resistance of YSZ thermal barrier coating

Abstract

The invention relates to a method for synchronously improving CMAS corrosion resistance and thermal shock resistance of a YSZ thermal barrier coating. The method comprises the following steps that firstly, a bonding layer and a YSZ thermal barrier coating are sequentially prepared on the surface of a base body; and then an Al2O3 composite coating is prepared on the surface of the YSZ thermal barrier coating through an atmospheric plasma spraying method, and on the premise that the thermal insulation requirement of the YSZ coating is met, the CMAS corrosion resistance and the thermal shock resistance of the YSZ thermal barrier coating are synchronously improved by controlling raw material powder for preparing a protective layer, controlling spraying process parameters and controlling the thickness of the protective layer. The process is flexible and simple, the cost is low, the applicability is high, compared with a YSZ coating not sprayed with a protective layer, after the protective layer is sprayed, CMAS corrosion is conducted for 8-10 h at the temperature of 1200-1250 DEG C, the structure and phase stability of the YSZ coating can still be kept, and the thermal shock resistance can be improved by 33%.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal barrier coatings, and in particular is a method for synchronously improving the CMAS corrosion resistance and thermal shock resistance of a YSZ thermal barrier coating. Background Art

[0002] Thermal barrier coatings (TBCs) are widely used in the hot end components of aircraft engines. They isolate the high-temperature alloy substrate from the high-temperature combustion gas, reduce the degree of damage to the alloy components, and improve the efficiency and durability of the engine. At present, the thermal barrier coating material with the best comprehensive performance and the most widely used is 6-8wt% yttria partially stabilized zirconia (6-8YSZ). However, with the continuous increase in the operating temperature of aircraft engines, the molten salt (CaO-MgO-Al2O3-SiO2, CMAS) corrosion problem faced by YSZ thermal barrier coatings has become more and more serious. Since the operating temperature of the engine has exceeded the melting point of CMAS, CMAS melts, wets, spreads, and adheres to the surface of the coating, and then penetrates into the interior of the coating through the openings and cracks on the surface of the coating, causing damage to the coating. At high temperatures, the damage of CMAS to thermal barrier coatings is mainly the coupling of thermomechanical and thermochemical effects. In terms of thermomechanical effects, molten CMAS will wet, diffuse and penetrate into the coating, fill the pores and cracks in the coating, and densify the coating, resulting in an increase in thermal conductivity and a decrease in strain tolerance. Due to the mismatch in the coefficient of thermal expansion (CTE) between the glassy CMAS and the coating, the coating will peel off during hot and cold cycles. In terms of thermochemical effects, CMAS can dissolve the coating, causing a phase change in the coating and accelerating the sintering of the coating. For YSZ thermal barrier coatings, since Y2O3 in YSZ dissolves in CMAS, the t′ phase ZrO2 becomes unstable and dissolves, and spherical m-phase ZrO2 grains are precipitated during the cooling process. The above phase change process is accompanied by a volume expansion of 3% to 5%, thereby generating internal stress, leading to crack initiation and expansion. The interaction between CMAS and the coating destroys the structure and phase stability of the coating, resulting in the degradation of the thermophysical properties of the coating and accelerating the failure of the coating.

[0003] Scholars have conducted extensive research on the CMAS corrosion problem of YSZ thermal barrier coatings. New thermal barrier coating materials resistant to CMAS corrosion are used to replace YSZ, such as rare earth zirconates, rare earth silicates, rare earth phosphates, hexaaluminates, etc. Or YSZ is doped and modified with Al2O3, TiO2 or rare earth oxides. These new thermal barrier coatings can interact with CMAS, promote the rapid crystallization of molten CMAS, and form continuous dense layers such as apatite near the coating surface, thereby preventing CMAS from further penetration. Although these new thermal barrier coating materials have good resistance to CMAS corrosion, they have other shortcomings in performance, such as high thermal conductivity, low thermal expansion coefficient, poor preparability, etc., and the overall performance of the coating is far inferior to YSZ.

[0004] Preparing a protective layer or performing surface modification on the surface of the YSZ coating is a more effective method. A Chinese patent (publication number CN 108004543 A) proposes to prepare a 3-5 μm Pt surface layer on the surface of the YSZ coating to prevent CMAS corrosion. A Chinese patent (publication number CN 111005024 A) uses a slurry method to prepare a MAX phase protective layer on the YSZ ceramic layer. The composition of the MAX phase is one or a combination of Ti2AlC, Ti3AlC2, Cr2AlC, Ti3SiC2, Ti2AlN, V2AlN or Zr2Al4C5 to prevent CMAS corrosion. Mohan P et al. (reference: Mohan P, Yao B, Patterson T, Sohn Y H. Surface and Coatings Technology 2009, 204: 797-801) uses electrophoretic deposition to prepare Al2O3 on the surface of the YSZ coating, and then sintering to obtain a dense protective layer to prevent the penetration of CMAS. A Chinese patent (publication number CN 111099893A) improves the corrosion resistance of thermal barrier coatings against molten CMAS by laser surface treatment. Although these methods have achieved certain beneficial effects, they still have limitations, such as complex processes or expensive materials. In addition, the mismatch between the thermal expansion coefficient of the protective layer and the YSZ coating or the change in the surface state of the YSZ coating caused by laser remelting will lead to a decrease in the thermal shock resistance of the coating. These methods are still in the laboratory research stage. Summary of the invention

[0005] The purpose of the present invention is to address the problem that the current YSZ thermal barrier coating is susceptible to CMAS corrosion, and to consider the current situation that the existing method improves the CMAS corrosion resistance of the coating while potentially reducing the thermal insulation performance or thermal shock resistance of the coating, and proposes a method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of the YSZ thermal barrier coating. The method adopts an atmospheric plasma spraying method to prepare a layer of Al2O3 composite coating on the surface of the YSZ thermal barrier coating. Under the premise of meeting the thermal insulation requirements of the YSZ coating, the raw material powder for preparing the protective layer, the spraying process parameters and the thickness of the protective layer are controlled to achieve the simultaneous improvement of the CMAS corrosion resistance and thermal shock resistance of the thermal barrier coating. The process of the present invention is flexible, simple, low-cost and highly applicable. Compared with the YSZ coating without spraying the protective layer, the thermal barrier coating after spraying the protective layer has better CMAS corrosion resistance at 1200-1250°C, and the thermal shock resistance can be improved by 33%.

[0006] The technical solution of the present invention is as follows:

[0007] A method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of a YSZ thermal barrier coating, the method comprising the following steps:

[0008] 1) Preparation of YSZ thermal barrier coating;

[0009] The substrate of the desired coating is degreased and sandblasted, and then a bonding layer and a YSZ thermal barrier coating are sequentially prepared on the surface of the substrate;

[0010] The bonding layer is made of NiAl or MCrAlY, where M represents Ni, Co or NiCo, and has a thickness of 80 to 150 μm. It can be prepared by atmospheric plasma spraying or supersonic flame spraying.

[0011] The YSZ thermal barrier coating is made of 6-8wt.% yttria-stabilized zirconia and has a thickness of 250-350μm. It can be prepared by an atmospheric plasma spraying method, an electron beam physical vapor deposition method or a plasma spray physical vapor deposition method.

[0012] The material of the substrate is nickel-based high-temperature alloy, cobalt-based high-temperature alloy, intermetallic compound or titanium alloy;

[0013] 2) Preparation of surface protective layer feeding powder;

[0014] The binder and deionized water are mixed, and stirred in a water bath at 70 to 80°C for 1.5 to 2 hours to form a colloid; the raw material powder, colloid, dispersant, and deionized water are mixed, and stirred with a stirrer for 1.5 to 2 hours to form a slurry; and then a spray drying technology is used to prepare a spherical powder for plasma spraying;

[0015] The mass ratio of the binder and deionized water used to prepare the colloid is 1-2:100; the mass ratio of the powder, colloid and dispersant in the slurry is 100:48-52:0.5-1.5, and the powder accounts for 30%-40% of the total mass of the slurry;

[0016] The raw material powder is one of the three composite powders of Al2O3-TiO2, Al2O3-YSZ or Al2O3-YSZ-TiO2; wherein the mass fraction of TiO2 in the Al2O3-TiO2 composite powder is 20% to 40%; the mass fraction of YSZ in the Al2O3-YSZ composite powder is 60% to 70%; the mass fraction of YSZ in the Al2O3-YSZ-TiO2 composite powder is 55% to 70%, and the mass fraction of TiO2 is 5 to 10%;

[0017] The binder is sodium carboxymethyl cellulose; the dispersant is sodium tripolyphosphate;

[0018] The air inlet temperature of the spray drying equipment is 230-240°C, and the air outlet temperature is 110-120°C;

[0019] The particle size of the raw material powder is in the range of 0.04 to 1 μm;

[0020] 3) Preparation of protective layer on the surface of YSZ thermal barrier coating:

[0021] The feed powder obtained in 2) is sprayed on the surface of the YSZ thermal barrier coating obtained in 1) by using an atmospheric plasma spraying method;

[0022] The plasma spraying process parameters are as follows: spraying power 32-38kW, spraying distance 80-100mm, gun speed 0.3-0.5m / s, Ar main gas flow 145-155dm 3 / min, H2 auxiliary gas flow rate 25~35dm 3 / min, powder feeding rate 0.10~0.18g / s;

[0023] The coating thickness is 30-50 μm;

[0024] The thermal barrier coating obtained by the method can still maintain structural and phase stability under CMAS corrosion at 1200-1250° C. for 8-10 hours, and can be thermally shocked under water cooling conditions of 1100° C. for 3-5 minutes, with the number of thermal cycles reaching 121 times.

[0025] The essential features of the present invention are:

[0026] By controlling the raw material powder, spraying process parameters and thickness of the protective layer, the coating's CMAS corrosion resistance, thermal shock resistance and surface mechanical properties are further improved without sacrificing the YSZ thermal barrier coating's excellent thermal insulation, thermal shock resistance and other comprehensive properties.

[0027] The beneficial effects of the present invention are:

[0028] (1) The raw materials Al2O3, YSZ, and TiO2 powders used in the present invention are easy to obtain and low in cost. The technologies used, such as spray drying technology and plasma spraying technology, are flexible, simple, low in cost, and highly applicable.

[0029] (2) The present invention prepares a protective layer of Al2O3-TiO2, Al2O3-YSZ, and Al2O3-YSZ-TiO2 with a thickness of 30 to 50 μm on the surface of the YSZ ceramic layer. The protective layer has a denser structure than the YSZ coating. On the one hand, it reduces the penetration path of molten CMAS, and on the other hand, it can react and crystallize with molten CMAS to generate a continuous dense layer with high melting point and high stability such as calcium feldspar and spinel to prevent further penetration of molten CMAS. At the same time, TiO2 in the protective layer can act as a nucleating agent to promote the occurrence of crystallization reaction. The coating has excellent anti-CMAS corrosion performance.

[0030] (3) Through the coordinated control of the protective layer composition, spraying process parameters and thickness, a protective layer with good matching with the YSZ thermal barrier coating, high stability and good protective effect can be obtained. First, the difference in thermal expansion coefficients between the protective layer and the YSZ coating can be reduced and the mechanical properties of the protective layer can be enhanced by designing the feed composition of the spraying protective layer and optimizing the spraying process parameters. Second, the thickness range of the protective layer can be controlled to prepare a thinner protective layer. During use, a thin protective layer is prone to produce a high-density network of surface microcracks, which effectively releases internal stress and prevents debonding at the interface between the protective layer and the YSZ coating. Third, the composition and thickness of the protective layer can be comprehensively controlled to improve the coating's resistance to CMAS corrosion (the underlying YSZ coating was not corroded after CMAS corrosion for 1 hour at 1250°C, such as Figure 3 Fourth, the dense protective layer has a lower oxygen permeability, which improves the anti-oxidation performance of the coating, prevents the rapid growth of thermally grown oxide (TGO), delays the failure of the ceramic layer / bonding layer interface caused by excessive growth of TGO, and significantly improves the thermal shock resistance of the coating. Figure 4 (a) and (b) show that compared with the YSZ coating without spraying protective layer, the thermal shock resistance of the coating after spraying protective layer can be improved by 33%.

[0031] (4) The coating is repairable. If the protective layer on the surface of YSZ is damaged or peeled off, the damaged protective layer can be removed mechanically and then sprayed again. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a cross-sectional schematic diagram of the surface protection layer-thermal barrier coating system of the present invention.

[0033] Figure 2 is a cross-sectional SEM image of the thermal barrier coating system in Example 2 including a 50 μm thick Al2O3-60wt.% 8YSZ protective layer.

[0034] Figure 3 It is a cross-sectional SEM image and corresponding element distribution diagram of the thermal barrier coating system including a 50 μm thick Al2O3-60wt.% 8YSZ protective layer in Example 2 after CMAS corrosion at 1250°C for 1 hour.

[0035] Figure 4 The 8YSZ coating obtained in Example 2 without spraying a protective layer and the 8YSZ coating sprayed with a 50 μm Al2O3-60wt.% 8YSZ protective layer after thermal shock under the conditions of 1100°C insulation for 5 minutes and water cooling; wherein, Figure 4 (a) is the macroscopic morphology of the 8YSZ coating after 91 thermal shocks; Figure 4 (b) The macroscopic morphology of the 8YSZ coating sprayed with a 50 μm thick Al2O3-60wt.% 8YSZ protective layer after 121 thermal shocks.

[0036] Figure 5 This is a surface SEM image of the thermal barrier coating system including a 50 μm thick Al2O3-60wt.% 8YSZ protective layer in Example 2 after 121 thermal shocks at 1100°C for 5 minutes under water cooling conditions.

[0037] Figure 6 This is a cross-sectional SEM image of the thermal barrier coating system in Example 2 including a 50 μm thick Al2O3-60wt.% 8YSZ protective layer after 121 thermal shocks at 1100°C for 5 minutes under water cooling conditions. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1: A 40 μm thick Al2O3-30 wt. % TiO2 protective layer was prepared on the surface of 8YSZ thermal barrier coating.

[0040] Step 1: Prepare YSZ coating. The substrate is made of GH3044 high-temperature alloy, which is cleaned and degreased with alcohol and sandblasted to ensure that the surface roughness of the substrate after sandblasting is 6-9μm. The bonding layer and YSZ coating materials are commercially available NiCrAlY spray powder and 8YSZ powder. A 100μm NiCrAlY bonding layer and a 300μm 8YSZ coating are sprayed on the substrate surface after sandblasting by plasma spraying.

[0041] The power for spraying the bonding layer is 30kW, the spraying distance is 100mm, the gun speed is 0.4m / s, and the Ar main gas flow rate is 150dm 3 / min, H2 auxiliary gas flow rate 20dm 3 / min, powder feeding rate 0.15g / s.

[0042] The power for spraying 8YSZ coating is 35kW, the spraying distance is 100mm, the gun speed is 0.3m / s, and the Ar flow rate is 150dm 3 / min, H2 flow rate 30dm 3 / min, powder feeding rate 0.15g / s.

[0043] Step 2: Preparation of composite powder for protective layer. Al2O3-30wt.% TiO2 composite powder is selected, and the particle size range of the composite powder is 0.04-1μm. The raw powder is weighed and mixed according to the proportion; the binder (sodium carboxymethyl cellulose) and deionized water are mixed at a ratio of 1.3:100, and stirred in a water bath at 80℃ for 2h to form a colloid. The mixed powder, colloid, dispersant (sodium tripolyphosphate) and deionized water are mixed and stirred with a stirrer for 2h to form a slurry. The mass ratio of powder, colloid and dispersant is 100:50:1, and the mass ratio of powder to total slurry is 35%. Spray drying technology is used to prepare spherical powder suitable for plasma spraying. The air inlet temperature of the spray drying equipment is 230-240℃, and the air outlet temperature is 110-120℃.

[0044] Step 3: Prepare an Al2O3-30wt.%TiO2 protective layer with a thickness of 40μm on the surface of the 8YSZ thermal barrier coating by using an atmospheric plasma spraying method.

[0045] Before spraying, ensure that the surface of 8YSZ coating is clean and pollution-free. The plasma spraying process parameters are as follows: spraying power 35kW, spraying distance 100mm, gun speed 0.35m / s, Ar main gas flow 150dm 3 / min, H2 auxiliary gas flow rate 30dm 3 / min, powder feeding rate 0.15g / s.

[0046] The cross-sectional schematic diagram of the obtained surface protection layer-thermal barrier coating system is shown in Figure 1 As shown, from bottom to top are the high-temperature alloy substrate, bonding layer, YSZ thermal barrier coating and protective layer.

[0047] Example 2: An Al2O3-60wt.% 8YSZ protective layer with a thickness of 50 μm was prepared on the surface of the 8YSZ coating.

[0048] The first step: the same as the first step in Example 1.

[0049] Step 2: Preparation of composite powder for protective layer. Al2O3-60 wt.% 8YSZ composite powder was selected. The raw powder was weighed and mixed according to the proportion, and the binder (sodium carboxymethyl cellulose) and deionized water were mixed at a ratio of 1.3:100, and stirred in a water bath at 80°C for 2 hours to form a colloid. The mixed powder, colloid, dispersant (sodium tripolyphosphate) and deionized water were mixed and stirred with a stirrer for 2 hours to form a slurry. The mass ratio of powder, colloid and dispersant was 100:50:1, and the mass ratio of powder to total slurry was 35%. Spray drying technology was used to prepare spherical powder suitable for plasma spraying. The air inlet temperature of the spray drying equipment was 230-240°C, and the air outlet temperature was 110-120°C.

[0050] Step 3: Prepare a YSZ-40wt.% Al2O3 protective layer with a thickness of 50 μm on the surface of the 8YSZ thermal barrier coating by using atmospheric plasma spraying.

[0051] Before spraying, ensure that the surface of 8YSZ coating is clean and pollution-free. The plasma spraying process parameters are as follows: spraying power 35kW, spraying distance 100mm, gun speed 0.35m / s, Ar main gas flow 150dm 3 / min, H2 auxiliary gas flow rate 30dm 3 / min, powder feeding rate 0.15g / s.

[0052] The cross-sectional polishing morphology of the obtained coating is as follows: Figure 2 As shown. It can be seen that the Al2O3-60wt.% 8YSZ coating is denser than the 8YSZ coating, which can greatly reduce the penetration channel of molten CMAS, thereby reducing the corrosion of CMAS on the 8YSZ coating. The dense structure also improves the oxidation resistance of the coating. The reason why the Al2O3-60wt.% 8YSZ coating is denser than the 8YSZ coating is that, on the one hand, the Al2O3 component has a lower melting point and the powder is easier to melt in the plasma flame. Second, Al2O3-YSZ (ZrO2) can form a eutectic, further reducing the melting point of the powder.

[0053] The CMAS powder was evenly coated on the surface of the obtained coating, and the polished cross section of the coating obtained by etching in a high-temperature furnace at 1250°C for 1 h and the corresponding element distribution were as follows: Figure 3 As shown in the figure, it can be seen that the 8YSZ coating at the bottom of the protective layer still maintains the sprayed morphology and is not corroded by CMAS. Most of the elements contained in the corrosive medium are distributed above the interface between the CMAS glass and the protective layer, reflecting the good permeation barrier effect of the protective layer.

[0054] The obtained coating was tested for its thermal shock resistance. The obtained coating was placed in a high-temperature furnace heated to 1100°C for 5 minutes, and then quickly placed in water at room temperature for cooling. This process was considered as one thermal cycle. Figure 4 The macroscopic morphology of the 8YSZ coating without spraying protective layer and the 8YSZ coating with spraying 50μm Al2O3-60wt.% 8YSZ protective layer after thermal shock. Figure 5 The figure shows the surface SEM image of the thermal barrier coating system containing a 50μm thick Al2O3-60wt.% 8YSZ protective layer after 121 thermal shocks at 1100℃. It can be seen that a high-density network of cracks is formed on the surface of the coating. The formation of the surface network cracks can absorb the energy of the main cracks and prevent the cracks from penetrating and extending, thereby increasing the strain tolerance of the coating, reducing the equivalent elastic modulus of the coating, and ultimately improving the thermal shock resistance.

[0055] Figure 6 This is a cross-sectional SEM image of a thermal barrier coating system containing a 50μm thick Al2O3-60wt.% 8YSZ protective layer after 121 thermal shocks at 1100°C. It can be seen that the network cracks extend longitudinally inside the protective layer. Due to the small thickness of the protective layer, it is more conducive to the generation of internal microcracks. In addition, the elastic strain energy stored in the cracks inside the thin protective layer is small, and it is difficult to penetrate into the 8YSZ ceramic layer below, and it is more inclined to terminate at the interface between the two layers. In addition, the high surface crack density is conducive to alleviating the formation of interface cracks and has a positive effect on preventing interface debonding. Under the same experimental conditions, the number of thermal cycles of the 8YSZ coating without a protective layer was only 91 times, and the number of thermal shocks reached 121 times after applying a 50μm Al2O3-60wt.% 8YSZ protective layer, and the thermal shock resistance was improved by 33%.

[0056] Example 3: An Al2O3-60wt.% 8YSZ-10wt.% TiO2 protective layer with a thickness of 30 μm was prepared on the surface of the 8YSZ thermal barrier coating.

[0057] The first step: the same as the first step in Example 1.

[0058] Step 2: Preparation of composite powder for protective layer. Al2O3-60wt.%8YSZ-10wt.%TiO2 composite powder was selected. The raw powder was weighed and mixed according to the proportion, and the binder (sodium carboxymethyl cellulose) and deionized water were mixed at a ratio of 1.3:100, and stirred in a water bath at 80℃ for 2 hours to form a colloid. The mixed powder, colloid, dispersant (sodium tripolyphosphate) and deionized water were mixed and stirred with a stirrer for 2 hours to form a slurry. The mass ratio of powder, colloid and dispersant was 100:50:1, and the mass ratio of powder to total slurry was 35%. Spray drying technology was used to prepare spherical powder suitable for plasma spraying. The air inlet temperature of the spray drying equipment was 230~240℃, and the air outlet temperature was 110~120℃.

[0059] Step 3: Prepare a 40 μm thick Al2O3-60wt.% 8YSZ-10wt.% TiO2 protective layer on the surface of the 8YSZ thermal barrier coating by using an atmospheric plasma spraying method.

[0060] Before spraying, ensure that the surface of 8YSZ coating is clean and pollution-free. The plasma spraying process parameters are as follows: spraying power 33kW, spraying distance 100mm, gun speed 0.35m / s, Ar main gas flow rate 150dm 3 / min, H2 auxiliary gas flow rate 25dm 3 / min, powder feeding rate 0.15g / s.

[0061] Embodiment 4:

[0062] The first step: the same as the first step in Example 1, except that the bonding layer preparation method is changed to a supersonic flame spraying method.

[0063] Step 2: Same as step 2 in Example 1.

[0064] Step 3: Same as step 3 in Example 1.

[0065] Embodiment 5:

[0066] The first step: the same as the first step in Example 1, except that the preparation method of the 8YSZ thermal barrier coating is changed to an electron beam physical vapor deposition method.

[0067] Step 2: Same as step 2 in Example 1.

[0068] Step 3: Same as step 3 in Example 1.

[0069] The foregoing embodiments of the present invention are described for the purpose of explanation and illustration, but those skilled in the art will understand that the following embodiments are only used to illustrate the present application, and are not intended to limit the present invention to the precise forms in the embodiments. Those skilled in the art can achieve this by referring to the contents of this article and appropriately changing the conditions, routes, etc., but it should be noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention.

[0070] Matters not covered by the present invention are known technologies.

Claims

1. A method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of a YSZ thermal barrier coating, characterized in that the method comprises the following steps: 1) Preparation of YSZ thermal barrier coating; The substrate of the desired coating is degreased and sandblasted, and then a bonding layer and a YSZ thermal barrier coating are sequentially prepared on the surface of the substrate; 2) Preparation of surface protective layer feeding powder; The binder and deionized water are mixed, and stirred in a water bath at 70 to 80°C for 1.5 to 2 hours to form a colloid; the raw material powder, colloid, dispersant, and deionized water are mixed, and stirred with a stirrer for 1.5 to 2 hours to form a slurry; and then a spray drying technology is used to prepare a spherical powder for plasma spraying; in, The mass ratio of the binder and deionized water used to prepare the colloid is 1-2:100; the mass ratio of the powder, colloid and dispersant in the slurry is 100:48-52:0.5-1.5, and the powder accounts for 30%-40% of the total mass of the slurry; The raw material powder is one of the three composite powders of Al2O3-TiO2, Al2O3-YSZ or Al2O3-YSZ-TiO2; the particle size of the raw material powder ranges from 0.04 to 1 μm; the mass fraction of TiO2 in the Al2O3-TiO2 composite powder is 20% to 40%; the mass fraction of YSZ in the Al2O3-YSZ composite powder is 60% to 70%; the mass fraction of YSZ in the Al2O3-YSZ-TiO2 composite powder is 55%-70%, and the mass fraction of TiO2 is 5 to 10%; 3) Preparation of protective layer on the surface of YSZ thermal barrier coating: The feed powder obtained in 2) is sprayed on the surface of the YSZ thermal barrier coating obtained in 1) by using an atmospheric plasma spraying method; The plasma spraying process parameters are as follows: spraying power 32-38kW, spraying distance 80-100mm, gun speed 0.3-0.5m / s, Ar main gas flow 145-155dm 3 / min, H2 auxiliary gas flow rate 25~35dm 3 / min, powder feeding rate 0.10~0.18g / s.

2. The method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of YSZ thermal barrier coating according to claim 1, characterized in that In step 1), the bonding layer is made of NiAl or MCrAlY, where M represents Ni, Co or NiCo, and has a thickness of 80 to 150 μm; the preparation method is atmospheric plasma spraying or supersonic flame spraying; The YSZ thermal barrier coating is made of 6-8wt.% yttria-stabilized zirconia and has a thickness of 250-350 μm. The preparation method is atmospheric plasma spraying, electron beam physical vapor deposition or plasma spray physical vapor deposition. The material of the substrate is nickel-based high-temperature alloy, cobalt-based high-temperature alloy, intermetallic compound or titanium alloy.

3. The method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of YSZ thermal barrier coating according to claim 1, characterized in that In step 2), the binder is sodium carboxymethyl cellulose; and the dispersant is sodium tripolyphosphate.

4. The method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of YSZ thermal barrier coating according to claim 1, characterized in that In step 2), the air inlet temperature of the spray drying equipment is 230-240°C, and the air outlet temperature is 110-120°C.

5. The method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of YSZ thermal barrier coating according to claim 1, characterized in that The coating thickness of the protective layer obtained in step 3) is 30 to 50 μm.

6. The method for simultaneously improving the CMAS corrosion resistance and thermal shock resistance of YSZ thermal barrier coating as described in claim 1, characterized in that the obtained thermal barrier coating can still maintain structural and phase stability after CMAS corrosion for 8 to 10 hours at 1200 to 1250°C, and can withstand thermal shock under water cooling conditions of 1100°C for 3 to 5 minutes, and the number of thermal cycles reaches 121 times.

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