Physical and chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating and preparation method thereof

Abstract

The invention discloses a physicochemical synergistic CMAS corrosion resistant rare earth co-doped zirconia thermal barrier coating and a preparation method thereof, and the preparation method comprises the following steps: carrying out ball milling on slurry containing multi-element rare earth co-doped zirconia ceramic powder, a binder and water, and carrying out powder agglomeration to obtain agglomerated ceramic powder; the method comprises the following steps: spraying the surface of a high-temperature alloy sample by adopting a wide-speed-range high-energy plasma spraying technology to form a bonding layer, and then spraying agglomerated ceramic powder to form a ceramic coating; and femtosecond laser processing etching is conducted on the surface of the ceramic coating, a laser surface modification layer is formed, and finally the physicochemical synergistic CMAS corrosion resisting rare earth co-doped zirconium oxide thermal barrier coating is formed. The thermal barrier coating shows excellent CMAS corrosion resistance at the high temperature of 1400 DEG C. Through the synergistic effect of physical morphology regulation and chemical component optimization, low cost, high reliability and industrialization potential are considered, and a new thought is provided for efficient protection of aero-engine hot end components.

Description

Technical Field

[0001] The invention belongs to the technical field of surface processing of thermal protection coatings, and particularly relates to a rare earth co-doped zirconia thermal barrier coating with physical and chemical synergistic anti-CMAS corrosion and a preparation method thereof. Background Art

[0002] Due to its good heat insulation effect, the thermal barrier coating is widely used on the surface of hot end components such as turbine or engine blades, thus greatly extending the service life of the blades and increasing the working temperature. With the development of aero-engines towards higher thrust-to-weight ratios and higher temperatures, CaO-MgO-Al2O3-SiO2 (CMAS) high-temperature molten salt corrosion has become one of the key factors limiting the working temperature and service life of thermal barrier coatings. The traditional yttria-stabilized zirconia (YSZ) coating is not suitable for long-term service above 1200 °C. After the CMAS melt penetrates into the coating at high temperature, the stabilizer Y2O3 dissolves in the CMAS melt, reducing the stability of YSZ and causing a phase transformation from the tetragonal phase to the monoclinic phase. Moreover, the components of CMAS, CaO, Al2O3, and SiO2, are distributed at the grain boundaries of YSZ and act as sintering aids to accelerate the sintering of the coating.

[0003] For the corrosion problem of CMAS to the thermal barrier coating, two solutions have been proposed: one is to develop a new thermal barrier coating material to replace the traditional YSZ, mainly by adding various rare earth oxides to dope zirconia and preparing a dense CMAS barrier layer to prevent the penetration of CMAS and the chemical reaction between CMAS and the material. However, compared with the traditional YSZ, the mechanical properties of the new material are not good at present, and there are great limitations. The other is to change the surface structure of the coating to affect the high-temperature reaction wetting and penetration behavior of the coating during the CMAS corrosion process, thereby reducing the premature failure of the coating caused by CMAS corrosion. Usually, laser processing technology is used to modify the surface of the coating. However, laser glazing changes the coating structure by melting and then re-solidifying the coating, and the resulting segmented cracks are inevitable.

[0004] The existing patent (CN111099893A) forms a modified layer containing non-penetrating longitudinal cracks on the surface of the ceramic layer through laser treatment with specific parameters. Although the longitudinal cracks can release stress, the formation and distribution of the cracks need to be precisely controlled. Otherwise, they may become new channels for corrosion, and the anti-CMAS corrosion performance is poor. Summary of the Invention

[0005] To solve the problem of poor CMAS corrosion resistance of ceramic coatings in the existing technology, the purpose of the present invention is to provide a physical and chemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating and a preparation method thereof. This method prepares GdScYSZ and GdNbYSZ ceramic coatings with excellent comprehensive properties of low thermal conductivity, high fracture toughness, high-temperature phase stability, and CMAS corrosion resistance through wide-speed-range high-energy plasma spraying, and performs femtosecond laser processing on the ceramic layer to make the surface have a double micro-convex topological structure, further slowing down the wetting and diffusion of molten CMAS on the ceramic surface. At the same time, the segmented cracks caused by laser melting and re-solidification of the coating can release thermal stress, improve the thermal cycle life, and exhibit excellent CMAS resistance under the long-term high-temperature service conditions of aeroengines.

[0006] To achieve the above object, the present invention provides the following technical solutions to be realized:

[0007] A preparation method of a physical and chemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating, comprising the following steps:

[0008] After ball-milling the slurry containing multi-rare earth co-doped zirconia ceramic powder, binder and water, powder agglomeration is carried out to obtain agglomerated ceramic powder.

[0009] Adopt wide-speed-range high-energy plasma spraying technology to spray on the surface of the sandblasted superalloy specimen to form a bonding layer, and then spray the agglomerated ceramic powder to form a ceramic coating.

[0010] The surface of the ceramic coating is etched by femtosecond laser processing to form a laser surface modification layer, and finally a physical and chemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating is formed.

[0011] Further, the binder is polyvinyl alcohol.

[0012] Further, the solid content in the slurry is 50wt.%, the binder is 1wt.%, and the deionized water is 49wt.%.

[0013] Further, the rotation speed of the ball-milling is 300 - 400 r / min, and the ball-milling time is 8 - 12 h.

[0014] Further, the powder agglomeration is carried out by a centrifugal spray granulation dryer, and the process parameters of the centrifugal spray granulation dryer are: the inlet air temperature is 200 - 220 °C, the centrifugal frequency is 250 - 270 Hz, and the feed rate is 20 - 40 mL / min.

[0015] Further, the process parameters of the wide-speed-range high-energy plasma-sprayed ceramic coating are as follows: current is 430 - 550 A, voltage is 121 - 148 V, main gas argon flow rate is 80 - 120 L / min, secondary gas hydrogen flow rate is 16 - 22 L / min, spraying distance is 80 - 110 mm, and powder feeding rate is 16 - 30 g / min.

[0016] Further, the laser pulse duration is 50 - 80 fs, the wavelength is 800 - 1000 nm, the frequency is 1 - 1.2 kHz, the laser scanning speed is 2 - 3 mm / s, and the average laser power is 20 - 30 mW.

[0017] A physicochemical synergistic CMAS corrosion-resistant rare-earth co-doped zirconia thermal barrier coating, the thermal barrier coating includes a bond coat, a ceramic coating, and a laser surface modification layer from bottom to top.

[0018] Further, the thickness of the bond coat is 50 - 150 μm, and the bond coat material is NiCrAlY, NiCoCrAlY, or CoNiCrAlY.

[0019] Further, the thickness of the ceramic coating is 300 - 400 μm; the laser surface modification layer includes a circular pit array with a diameter of 14 - 18 μm and closely arranged periodically, and a periodic square pit array with a size of 40×40 μm, a depth of 15 - 20 μm, and a spacing of 20 - 25 μm. The internal structure of the pit type is a rod-shaped micro-protrusion structure.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention uses a wide-speed-range high-energy plasma spraying technology to prepare GdScYSZ and GdNbYSZ ceramic coatings with low thermal conductivity, high fracture toughness, high-temperature phase stability, and excellent CMAS corrosion resistance. Then, the surface of the ceramic layer is treated by femtosecond laser etching to obtain a pit structure with regular periodic arrangement. The internal structure of the pit is a rod-shaped micro-protrusion, which further slows down the wetting and diffusion of molten CMAS on the ceramic surface. At the same time, the segmented cracks caused by the re-solidification after laser melting of the coating can release thermal stress and improve the thermal cycle life. And in the present invention, elements such as Sm, Eu, Gd, and Dy are not used, so the cost is low.

[0022] Furthermore, the present invention combines femtosecond laser processing with GdScYSZ and GdNbYSZ materials. Firstly, a double micro-convex topological structure is constructed on the surface of the thermal barrier coating through a physical anti-adhesion strategy to precisely regulate the surface morphology and limit the adhesion of CMAS droplets on the coating surface. On the other hand, relying on the strategy of in-situ forming a barrier layer through the high-temperature chemical reaction of elements such as Gd, Sc, Nb, and Y with CMAS, a rare-earth-rich in-situ reaction layer is formed on the coating surface, shortening the growth cycle of the dense reaction layer of rare earths such as Gd and Sc. The addition of Sc2O3 makes the coating have better t'-phase structure stability and high density, which can effectively inhibit the infiltration of CMAS; the addition of Gd2O3 quickly reacts with CMAS to form a dense Gd-apatite phase Ca2Gd8(SiO4)6O2. This dense CMAS barrier layer is intertwined with the dissolved and re-precipitated c-ZrO2 particles, effectively hindering the penetration of CMAS; for niobium element, considering the large ion radius difference from other doped rare earth elements, the resulting large lattice distortion can reduce the element diffusion rate and reduce the reaction activity with Ca 2+ , Si 4+ plasma, thus delaying the corrosion process. In addition, niobium doping promotes the formation of an inert interfacial reaction layer, and further blocks the penetration path of molten CMAS by forming a dense perovskite or spinel phase (such as CaNb2O6). The present invention proposes to reduce the high-temperature reactivity at the CMAS / coating interface through physical / chemical synergy, and fundamentally improve the CMAS corrosion resistance of the coating. Brief Description of the Drawings

[0023] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0024] Figure 1 is the SEM micrograph of the spherical powder after spray granulation and agglomeration in Example 1 of the present invention;

[0025] Figure 2 is the SEM micrograph of the surface morphology of the GdScYSZ coating after wide-domain high-energy plasma spraying in Example 1 of the present invention; among them, (a) is the surface morphology of the as-sprayed coating; (b) is the surface morphology of the polished coating;

[0026] Figure 3 is the SEM micrograph of the cross-sectional morphology of the GdScYSZ coating after wide-domain high-energy plasma spraying in Example 1 of the present invention;

[0027] Figure 4 SEM photographs of the surface morphology of the coating after femtosecond laser processing and etching in Example 1 of the present invention; among them, (a) is the low-magnification morphology; (b) is the high-magnification morphology; (c) is the surface undulation measured by laser confocal microscopy;

[0028] Figure 5 SEM photographs of the surface morphology of the coating after femtosecond laser processing and etching in Example 2 of the present invention; among them, (a) is the low-magnification morphology; (b) is the high-magnification morphology; (c) is the surface undulation measured by laser confocal microscopy;

[0029] Figure 6 Photographs of Examples 1 and 2 of the present invention after high-temperature CMAS wetting test; among them, (a) is Example 1; (b) is Example 2;

[0030] Figure 7 SEM photographs of the cross-sectional morphology of the coating after CMAS corrosion test in Example 1 of the present invention; among them, (a) is the low-magnification morphology of the corrosion layer; (b) is the high-magnification morphology of the corrosion layer. Detailed implementation manners

[0031] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0032] A preparation method of a physicochemical synergistic CMAS-corrosion-resistant rare-earth co-doped zirconia thermal barrier coating of the present invention includes the following steps:

[0033] Step 1, chemically synthesize a sol-gel precursor and obtain nanocrystalline multi-rare-earth co-doped zirconia ceramic powder by a one-step pyrolysis method. The specific process is as follows: Mix three or four of gadolinium chloride, scandium chloride, niobium chloride, and yttrium chloride with zirconium oxychloride to obtain a mixture, and add the mixture and citric acid to deionized water to form a colorless transparent solution,

[0034] wherein, the total molar amount of metal ions in the mixture is 20-45% of the molar amount of zirconium oxychloride, and the ratio of the total molar amount of metal ions in the mixture to the molar amount of citric acid = 1:1.2-1.5.

[0035] When using three metal salts of gadolinium chloride, scandium chloride, and niobium chloride, the molar ratio of the three metal salts is 1:1:1;

[0036] When using four metal salts of gadolinium chloride, scandium chloride, niobium chloride, and yttrium chloride, the molar ratio of the four metal salts is 1:1:1:1;

[0037] Then, the colorless and transparent solution is heated at 60 - 80 °C for 20 - 24 h to obtain a wet gel, and the wet gel is calcined at 1000 - 1100 °C for 3 - 5 h to obtain nano - crystalline multi - rare - earth co - doped zirconia ceramic powder.

[0038] Step 2: Mix the nano - crystalline multi - rare - earth co - doped zirconia ceramic powder, binder (polyvinyl alcohol PVA), and water to obtain a slurry. Among them, the solid - phase content of the slurry ratio is 50 wt.%, the binder polyvinyl alcohol PVA is 1 wt.%, and deionized water is 49 wt.%. The prepared slurry is ball - milled by a planetary ball mill, the ball - milling speed is 300 - 400 r / min, and the ball - milling time is 8 - 12 h;

[0039] Then, the slurry is passed through a centrifugal spray granulation dryer to agglomerate the powder, obtaining an agglomerated ceramic powder body, which meets the requirements of the wide - range high - energy plasma spraying process and has good fluidity. Among them, the process parameters of the centrifugal spray granulation dryer are: the inlet air temperature is 200 - 220 °C, the centrifugal frequency is 250 - 270 Hz, and the feeding rate is 20 - 40 mL / min.

[0040] Step 3: Sandblast the surface of the superalloy specimen, and then spray on the surface of the superalloy specimen using the wide - speed - range high - energy plasma spraying technology to form a bonding layer. The thickness of the bonding layer is 50 - 150 μm, and the bonding layer material is NiCrAlY, NiCoCrAlY, or CoNiCrAlY, thereby obtaining a superalloy specimen with a bonding layer. Subsequently, spray the agglomerated ceramic powder body on the specimen surface to form a ceramic coating with a thickness of 300 - 400 μm. Among them, the process parameters of the wide - speed - range high - energy plasma spraying ceramic coating are: the current is 430 - 550 A, the voltage is 121 - 148 V, the main gas argon flow rate is 80 - 120 L / min, the secondary gas hydrogen flow rate is 16 - 22 L / min, the spraying distance is 80 - 110 mm, and the powder feeding rate is 16 - 30 g / min.

[0041] Step 4: Etch the surface of the ceramic coating obtained in Step 3 by femtosecond laser processing to form a laser surface modification layer, and finally form a physical - chemical synergistic anti - CMAS corrosion rare - earth co - doped zirconia thermal barrier coating. Among them, the laser pulse duration is 50 - 80 fs, the wavelength is 800 - 1000 nm, the frequency is 1 - 1.2 kHz, the laser scanning speed is 2 - 3 mm / s, and the laser average power is 20 - 30 mW.

[0042] By adopting different femtosecond laser processing parameters, circular pit arrays with diameters of 14 - 18 μm and closely arranged periodically can be obtained on the surface of the ceramic coating, as well as periodic square pit arrays with dimensions of 40×40 μm, depths of 15 - 20 μm, and intervals of 20 - 25 μm. There are rod-shaped micro-protrusion structures inside the pit-type structures. The smaller diameter of the circular pits and the closely arranged periodic structures significantly increase the surface roughness and reduce the effective contact area of CMAS molten salt. The square pits capture more CMAS molten salt through a larger surface area and geometric complexity, increasing the residence time of CMAS, and at the same time providing more buffer space for thermal expansion, which helps to uniformly release thermal stress. After high-temperature wetting angle testing, the contact angle of the CMAS melt is 112 - 113°.

[0043] The thermal barrier coating prepared by the present invention includes a laser surface modification layer, a ceramic coating, and a bonding layer provided on a superalloy substrate. The present invention prepares GdScYSZ and GdNbYSZ ceramic coatings with excellent comprehensive properties of low thermal conductivity, high fracture toughness, high-temperature phase stability, and resistance to CMAS corrosion through wide-speed-range high-energy plasma spraying, and performs femtosecond laser processing on the ceramic layer to make the surface have a double micro-protrusion topological structure, further slowing down the wetting and diffusion of molten CMAS on the ceramic surface. At the same time, the segmented cracks caused by laser melting and re-solidification of the coating can release thermal stress and improve the thermal cycle life. It shows excellent CMAS resistance under the long-term high-temperature service conditions of aeroengines.

[0044] Example 1

[0045] A preparation method of a physicochemical synergistic CMAS-corrosion-resistant rare-earth co-doped zirconia thermal barrier coating of the present invention includes the following steps:

[0046] Step 1: Mix gadolinium chloride, scandium chloride, yttrium chloride, and zirconium oxychloride in a molar ratio of 1:1:1:7 to obtain a mixture. According to the ratio of the total molar amount of metal ions in the mixture: the molar amount of citric acid = 1:1.25, dissolve the mixture and citric acid in deionized water to form a colorless transparent solution. Then, place the colorless transparent solution in a 60°C water bath and stir for 24 h for sol-gel reaction to obtain a wet gel. Place the wet gel in a 60°C oven for drying to finally obtain a dry gel precursor. Set the dry gel precursor in a muffle furnace at 1100°C for 4 h to prepare gadolinium scandium yttrium co-stabilized zirconia (GdScYSZ) ceramic powder.

[0047] Step 2: Mix the gadolinium scandium yttrium co-stabilized zirconia ceramic powder, a binder (polyvinyl alcohol PVA), and water to obtain a slurry. Among them, the weight concentration of the ceramic powder is 50 wt.%, the weight concentration of the binder polyvinyl alcohol PVA is 1 wt.%, and the weight concentration of deionized water is 49 wt.%.

[0048] The slurry is ball-milled by a planetary ball mill at a ball-milling speed of 400 r / min for 8 h, and then passed through a centrifugal spray granulation dryer to agglomerate the powder, obtaining agglomerated GdScYSZ ceramic powder. This ceramic powder meets the requirements of the wide-range high-energy plasma spraying process and has good fluidity, as Figure 1 shown.

[0049] Among them, the process parameters of the centrifugal spray granulation dryer are: the inlet air temperature is 220 °C, the centrifugal frequency is 250 Hz, and the feed rate is 20 mL / min.

[0050] Step 3: Sandblast the surface of the superalloy specimen, and then spray on the surface of the superalloy specimen using the wide-speed-range high-energy plasma spraying technology to form a bonding layer. The thickness of the bonding layer is 100 μm, and the bonding layer material is CoNiCrAlY, obtaining a superalloy specimen with a bonding layer;

[0051] Subsequently, the obtained agglomerated GdScYSZ ceramic powder is placed in a powder feeding device, and the agglomerated GdScYSZ ceramic powder is sprayed on the specimen surface to form a ceramic coating with a thickness of 400 μm.

[0052] Among them, the process parameters of the wide-speed-range high-energy plasma spraying ceramic coating are: the current is 470 A, the voltage is 130 V, the main gas argon flow rate is 100 L / min, the secondary gas hydrogen flow rate is 18 L / min, the spraying distance is 110 mm, and the powder feeding rate is 30 g / min.

[0053] Step 4: Etch the surface of the ceramic coating obtained in Step 3 by femtosecond laser processing to form a laser surface modification layer, thereby obtaining a physicochemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating. Among them, the laser pulse duration is 50 fs, the wavelength is 800 nm, the frequency is 1 kHz, the laser scanning speed is 2 mm / s, and the average laser power is 20 mW.

[0054] The surface morphology before processing is shown in Figure 2 (a) and (b) in it. It can be seen that the surface of the unpolished coating is stacked by a large number of flattened and sputtered molten particles, showing a wavy undulation. Due to the overflow of some gases or incomplete bonding between the lamellae during the spraying process, visible tiny pores are formed on the surface. The porosity of the polished coating surface is about 3-5%.

[0055] The surface morphology after processing is shown in Figure 4 (a) and (b) in it. It can be seen that a circular array with a diameter of 15 μm and closely arranged periodically is obtained on the coating surface, and a rod-shaped micro-protrusion structure is formed inside the circular pits. After the high-temperature wetting angle test, it is found that the contact angle of the cylindrical CMAS melt is 113°.

[0056] The cross-sectional morphology of the coating before the CMAS corrosion test is shown in Figure 3 . It can be seen that the coating exhibits a typical layered structure. The wide-area high-energy plasma spraying particles have a higher velocity, resulting in more sufficient flattening of the molten ceramic particles after high-speed impact on the substrate. The lamellae are thinner and stacked more densely, and the porosity is about 5-7%.

[0057] The cross-sectional morphology of the coating after the CMAS corrosion test is shown in Figure 7 (a) and (b) in it. It can be seen that spherical particles with larger particle sizes appear at the top of the coating. The main component of the spherical grains is m-phase ZrO2, indicating that the infiltration of CMAS leads to the phase structure transformation of the GdScYSZ thermal barrier coating from t'-phase to m-phase. The middle region shows a bimodal structure composed of spherical particles and elongated grains, and the CMAS infiltrated into the coating is wrapped by the elongated grains.

[0058] Example 2

[0059] Step 1 is the same as that in Example 1;

[0060] Step 2 is the same as that in Example 1;

[0061] Step 3 is the same as that in Example 1;

[0062] Step 4: The GdScYSZ ceramic coating obtained in Step 3 is subjected to femtosecond laser processing to etch the surface to form a laser surface modification layer, thereby obtaining a physicochemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating. Among them, the laser pulse duration is 50 fs, the wavelength is 1000 nm, the frequency is 1.2 kHz, the laser scanning speed is 2.5 mm / s, and the average laser power is 25 mW.

[0063] The surface morphology after processing is shown in Figure 5 (a), (b) and (c) in it. It can be seen that a periodic square array with a size of 40×40 μm and a spacing of 20 μm is obtained on the coating surface, and a rod-like micro-protrusion structure is presented inside the pit-type structure. After the high-temperature wetting angle test, it is found that the contact angle of the cylindrical CMAS melt is 112°.

[0064] CMAS is coated on the sample surface for the corrosion test. The CMAS concentration used in the corrosion experiment is generally expressed by the mass of the CMAS powder per unit area. In the present invention, the CMAS concentration of 30 g / cm 2 is adopted. After the corrosion test at 1400 °C for 2 h, the cross-sectional morphology of the coating is as shown in Figure 6As shown in (a) and (b) of the figure, it can be seen that an obvious dissolution and reprecipitation process has occurred. The zirconia grains in the coating will dissolve into the CMAS melt. After reaching the solubility limit, they will recrystallize to form small spherical particles. The diffusion coefficient of rare earth elements in the CMAS melt is greater than that of Zr elements, and they can react quickly with the CMAS molten salt to form a protective layer containing an apatite phase. As a result, the upper surface of the coating presents a dual-mode structure composed of spherical particles and fine needle-like grains, and the CMAS infiltrated into the coating is wrapped by slender grains, which hinders the wetting and further erosion of the molten CMAS. There is a reaction layer with a thickness of about 100 μm on the surface layer, and the reaction layer is very uniform.

[0065] Example 3

[0066] Step 1: Mix gadolinium chloride, scandium chloride, yttrium chloride and zirconium oxychloride in a molar ratio of 1:1:1:6.8 to obtain a mixture. According to the ratio of the total molar amount of metal ions in the mixture: the molar amount of citric acid = 1:1.2, dissolve the mixture and citric acid in deionized water to form a colorless transparent solution. Then, place the colorless transparent solution in a water bath at 80 °C and stir for 20 h for sol-gel reaction to obtain a wet gel. Place the wet gel in an oven at 60 °C for drying to finally obtain a dry gel precursor. Set the dry gel precursor in a muffle furnace at 1000 °C and hold for 54 h to prepare gadolinium scandium yttrium co-stabilized zirconia (GdScYSZ) ceramic powder.

[0067] Step 2: Mix gadolinium scandium yttrium co-stabilized zirconia ceramic powder, binder (polyvinyl alcohol PVA) and water to obtain a slurry. Among them, the weight concentration of the ceramic powder is 50 wt.%, the weight concentration of the binder polyvinyl alcohol PVA is 1 wt.%, and the weight concentration of deionized water is 49 wt.%.

[0068] Mill the slurry by a planetary ball mill at a ball milling speed of 300 r / min for 12 h, and then perform powder agglomeration through a centrifugal spray granulation dryer to obtain agglomerated GdScYSZ ceramic powder. This ceramic powder meets the requirements of the wide-range high-energy plasma spraying process and has good fluidity, as Figure 1 shown.

[0069] Among them, the process parameters of the centrifugal spray granulation dryer are: the inlet air temperature is 200 °C, the centrifugal frequency is 250 Hz, and the feeding rate is 40 mL / min.

[0070] Step 3: Sandblast the surface of the superalloy specimen, and then spray it on the surface of the superalloy specimen by wide-speed-range high-energy plasma spraying technology to form a bonding layer. The thickness of the bonding layer is 50 μm, and the bonding layer material is CoNiCrAlY to obtain a superalloy specimen with a bonding layer.

[0071] Subsequently, the obtained agglomerated GdScYSZ ceramic powder was placed in a powder feeding device, and the agglomerated GdScYSZ ceramic powder was sprayed on the surface of the specimen to form a ceramic coating with a thickness of 300 μm.

[0072] Among them, the process parameters of the wide-speed-range high-energy plasma spraying ceramic coating are: current is 550 A, voltage is 121 V, main gas argon flow rate is 80 L / min, secondary gas hydrogen flow rate is 16 L / min, spraying distance is 80 mm, and powder feeding rate is 16 g / min.

[0073] Step 4: The ceramic coating obtained in Step 3 was subjected to femtosecond laser processing to etch the surface to form a laser surface modification layer, thereby obtaining a physicochemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating. Among them, the laser pulse duration is 50 fs, the wavelength is 1000 nm, the frequency is 1 kHz, the laser scanning speed is 2 mm / s, and the laser average power is 25 mW.

[0074] Example 4

[0075] Step 1: Gadolinium chloride, scandium chloride, yttrium chloride and zirconium oxychloride were mixed in a molar ratio of 1:1:1:12 to obtain a mixture. According to the ratio of the total molar amount of metal ions in the mixture: the molar amount of citric acid = 1:1.5, the mixture and citric acid were dissolved in deionized water to form a colorless transparent solution. Then, the colorless transparent solution was placed in a water bath at 60 °C and stirred for 24 h for sol-gel reaction to obtain a wet gel. The wet gel was placed in an oven at 60 °C for drying, and finally a dry gel precursor was obtained. The dry gel precursor was set in a muffle furnace at 1100 °C for 3 h to prepare gadolinium scandium yttrium co-stabilized zirconia (GdScYSZ) ceramic powder.

[0076] Step 2: The gadolinium scandium yttrium co-stabilized zirconia ceramic powder, binder (polyvinyl alcohol PVA) and water were mixed to obtain a slurry. Among them, the weight concentration of the ceramic powder is 50 wt.%, the weight concentration of the binder polyvinyl alcohol PVA is 1 wt.%, and the weight concentration of deionized water is 49 wt.%.

[0077] The slurry was ball-milled by a planetary ball mill at a ball-milling speed of 350 r / min for 12 h, and then the powder was agglomerated by a centrifugal spray granulation dryer to obtain agglomerated GdScYSZ ceramic powder. This ceramic powder meets the requirements of the wide-range high-energy plasma spraying process and has good fluidity, as Figure 1 shown.

[0078] Among them, the process parameters of the centrifugal spray granulation dryer are: inlet air temperature is 210 °C, centrifugal frequency is 270 Hz, and feed rate is 30 mL / min.

[0079] Step 3: Sandblast the surface of the superalloy specimen, and then spray on the surface of the superalloy specimen using the wide-speed-range high-energy plasma spraying technology to form a bonding layer. The thickness of the bonding layer is 150 μm, and the material of the bonding layer is CoNiCrAlY, obtaining a superalloy specimen with a bonding layer.

[0080] Subsequently, place the obtained agglomerated GdScYSZ ceramic powder in a powder feeding device, and spray the agglomerated GdScYSZ ceramic powder on the specimen surface to form a ceramic coating with a thickness of 400 μm.

[0081] Among them, the process parameters of the wide-speed-range high-energy plasma spraying ceramic coating are: current is 430 A, voltage is 148 V, main gas argon flow rate is 120 L / min, secondary gas hydrogen flow rate is 20 L / min, spraying distance is 100 mm, and powder feeding rate is 29 g / min.

[0082] Step 4: Perform femtosecond laser processing and etching on the surface of the ceramic coating obtained in Step 3 to form a laser surface modification layer, thereby obtaining a physicochemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating. Among them, the laser pulse duration is 70 fs, the wavelength is 900 nm, the frequency is 1.1 kHz, the laser scanning speed is 3 mm / s, and the laser average power is 30 mW.

[0083] Example 5

[0084] Step 1: Mix gadolinium chloride, scandium chloride, yttrium chloride and zirconium oxychloride in a molar ratio of 1:1:1:1:1 to obtain a mixture. According to the ratio of the total molar amount of metal ions in the mixture: the molar amount of citric acid = 1:1.4, dissolve the mixture and citric acid in deionized water to form a colorless transparent solution. Then place the colorless transparent solution in a 70 °C water bath and stir for 22 h for sol-gel reaction to obtain a wet gel. Place the wet gel in an oven at 60 °C for drying to finally obtain a dry gel precursor. Set the dry gel precursor in a muffle furnace at 1050 °C for 5 h to prepare gadolinium scandium yttrium co-stabilized zirconia (GdScYSZ) ceramic powder.

[0085] Step 2: Mix the gadolinium scandium yttrium co-stabilized zirconia ceramic powder, binder (polyvinyl alcohol PVA) and water to obtain a slurry. Among them, the weight concentration of the ceramic powder is 50 wt.%, the weight concentration of the binder polyvinyl alcohol PVA is 1 wt.%, and the weight concentration of deionized water is 49 wt.%;

[0086] Ball mill the slurry using a planetary ball mill. The ball milling speed is 380 r / min, and the ball milling time is 11 h. Then, through a centrifugal spray granulation dryer, perform powder agglomeration to obtain agglomerated GdScYSZ ceramic powder. This ceramic powder meets the requirements of the wide-domain high-energy plasma spraying process and has good fluidity, asFigure 1 as shown

[0087] Among them, the process parameters of the centrifugal spray granulation dryer are: the inlet air temperature is 220 °C, the centrifugal frequency is 260 Hz, and the feeding rate is 20 mL / min.

[0088] Step 3: Sandblast the surface of the superalloy specimen, and then spray on the surface of the superalloy specimen by using the wide-speed-range high-energy plasma spraying technology to form a bonding layer. The thickness of the bonding layer is 130 μm, and the material of the bonding layer is CoNiCrAlY, obtaining a superalloy specimen with a bonding layer;

[0089] Subsequently, the obtained agglomerated GdScYSZ ceramic powder is placed in a powder feeding device, and the agglomerated GdScYSZ ceramic powder is sprayed on the specimen surface to form a ceramic coating with a thickness of 350 μm.

[0090] Among them, the process parameters of the wide-speed-range high-energy plasma spraying ceramic coating are: the current is 500 A, the voltage is 135 V, the main gas argon flow rate is 110 L / min, the secondary gas hydrogen flow rate is 22 L / min, the spraying distance is 90 mm, and the powder feeding rate is 25 g / min.

[0091] Step 4: Etch the surface of the ceramic coating obtained in Step 3 by femtosecond laser processing to form a laser surface modification layer, thereby obtaining a physical and chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating. Among them, the laser pulse duration is 80 fs, the wavelength is 850 nm, the frequency is 1.2 kHz, the laser scanning speed is 2.5 mm / s, and the average laser power is 23 mW.

[0092] In view of the CMAS corrosion problem of thermal barrier coatings in the high-temperature environment of aeroengines, the present invention develops a physical and chemical synergistic protection strategy combining material optimization and surface structure design. Prepare multi-principal-element rare earth co-doped zirconia ceramic powder by the sol-gel method, and use the wide-domain high-energy plasma spraying technology to construct a layered coating substrate with low thermal conductivity and high fracture toughness. Further adopt the femtosecond laser etching technology to precisely process a periodic pit-rod-shaped micro-protrusion double-topology structure on the coating surface, and significantly reduce the wetting and penetration ability of the CMAS melt through physical morphology regulation. The experimental results show that the rare earth-rich reaction layer formed by the modified coating at 1400 °C can effectively wrap the CMAS molten salt and block its further erosion, showing excellent anti-CMAS corrosion performance; at the same time, the laser-induced microcracks release the thermal stress and extend the thermal cycle life of the coating. Compared with the traditional method, this method combines the physical morphology regulation (surface modification) and chemical composition optimization, taking into account low cost, high reliability and industrialization potential, providing a new idea for the efficient protection (reliability and durability) of the hot-end components of aeroengines.

[0093] The above description is only for the best embodiments of the present invention, but it should not be construed as a limitation on the claims. The present invention is not limited to the above embodiments, and its specific structure allows for variations. Any variations made within the scope of the protection of the independent claims of the present invention are within the scope of the present invention.

[0094] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A preparation method of a physical and chemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating, characterized in that It includes the following steps: After ball-milling the slurry containing multi-element rare earth co-doped zirconia ceramic powder, binder and water, powder agglomeration is carried out to obtain agglomerated ceramic powder; Using a wide-speed-range high-energy plasma spraying technology to spray on the surface of the sand-blasted superalloy specimen to form a bonding layer, and then spraying the agglomerated ceramic powder to form a ceramic coating; The surface of the ceramic coating is etched by femtosecond laser processing to form a laser surface modification layer, and finally a physical and chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating is formed.

2. The preparation method of the physical-chemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating according to claim 1, characterized in that The binder is polyvinyl alcohol.

3. The preparation method of the physical-chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating according to claim 1, characterized in that The solid content in the slurry is 50wt.%, the binder is 1wt.%, and deionized water is 49wt.%.

4. The preparation method of the physical-chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating according to claim 1, wherein The rotation speed of ball-milling is 300 - 400r / min, and the ball-milling time is 8 - 12h.

5. The preparation method of the physical and chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating according to claim 1, characterized in that The powder agglomeration is carried out by a centrifugal spray granulation dryer, and the process parameters of the centrifugal spray granulation dryer are: the inlet air temperature is 200 - 220°C, the centrifugal frequency is 250 - 270Hz, and the feed rate is 20 - 40mL / min.

6. The preparation method of the physical-chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating according to claim 1, wherein, The process parameters of the wide-speed-range high-energy plasma spraying ceramic coating are: the current is 430 - 550A, the voltage is 121 - 148V, the main gas argon flow rate is 80 - 120L / min, the secondary gas hydrogen flow rate is 16 - 22L / min, the spraying distance is 80 - 110mm, and the powder feeding rate is 16 - 30g / min.

7. The preparation method of the physical-chemical synergistic CMAS corrosion-resistant rare earth co-doped zirconia thermal barrier coating according to claim 1, characterized in that, The laser pulse duration is 50 - 80fs, the wavelength is 800 - 1000nm, the frequency is 1 - 1.2kHz, the laser scanning speed is 2 - 3mm / s, and the laser average power is 20 - 30mW.

8. A physicochemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating prepared by the method according to any one of claims 1-7, characterized in that, The thermal barrier coating includes a bonding layer, a ceramic coating and a laser surface modification layer from bottom to top.

9. The physical-chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating according to claim 8, wherein, The thickness of the bonding layer is 50 - 150μm, and the bonding layer material is NiCrAlY, NiCoCrAlY or CoNiCrAlY.

10. The physical-chemical synergistic anti-CMAS corrosion rare earth co-doped zirconia thermal barrier coating according to claim 8, characterized in that, The thickness of the ceramic coating is 300 - 400μm; the laser surface modification layer includes a circular pit array with a diameter of 14 - 18μm and closely arranged periodically, and a periodic square pit array with a size of 40×40μm, a depth of 15 - 20μm and a spacing of 20 - 25μm. The inside of the pit-type structure is a rod-shaped micro-protrusion structure.

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