Composite thermal barrier coating and method of making same

Abstract

The present application relates to thermal barrier coating material technical field, disclose a kind of composite thermal barrier coating, including layer by layer superimposed metal bonding layer, ceramic thermal barrier layer, ceramic oxygen barrier transition layer and ceramic ablation resistance layer, the metal bonding layer is close to the surface of the base body to be coated;The ceramic thermal barrier layer is YSZ coating doped with multielement rare earth oxide, and the multielement rare earth oxide is selected from two or more of CeO2, La2O3, Sm2O3, Yb2O3.The composite thermal barrier coating of the present application utilizes the synergistic effect of different high-temperature characteristics of each layer of material, can withstand more than 1600 DEG C superhigh temperature environment, realize excellent high-temperature oxidation resistance, ablation resistance, thermal insulation and other comprehensive thermal protection performance;Through the reasonable selection and setting of each layer of material, heat gradient regulation can be realized, the thermal stress caused by thermal expansion mismatch is reduced, the problem of easy peeling failure of coating in temperature sudden change is solved, and the overall performance of the composite thermal barrier coating is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal barrier coating materials, in particular to a composite thermal barrier coating and a preparation method thereof. BACKGROUND

[0002] With the in-depth development of national manned spaceflight, deep space exploration, hypersonic vehicle and other technologies, the flight speed of the vehicle is continuously improved. The hot end components (nozzle, combustion chamber, turbine blade, nose cone, etc.) need to withstand the harsh environment of super 1600℃ high temperature, cold and hot impact, high temperature airflow scouring, etc. during operation, and also need to withstand long-time high temperature service, which puts forward extremely high and even unattainable requirements for the heat protection and thermal insulation comprehensive performance of the vehicle metal structural parts.

[0003] Coating a thermal protection coating with excellent thermal insulation and other properties on the surface of the vehicle metal substrate can effectively prevent the oxidation, ablation and impact damage of the substrate metal, thereby significantly improving the service life of the component. Thermal barrier coating is a typical thermal insulation coating, which is widely used as a high-temperature protective coating to improve the durability and performance of gas turbines, aircraft engines, etc.

[0004] At present, the most widely used thermal barrier coating ceramic material is Y2O3 partially stabilized ZrO2 (Yittium Partially Stabilized Zirconia, abbreviated as YSZ). YSZ thermal barrier coating can exhibit excellent comprehensive performance at service temperature (below 1200℃). However, phase transition will occur at high temperature above 1200℃, which will cause the volume of the coating to increase and form cracks, and the Y2O3 in the ceramic layer will be continuously consumed by reacting with the medium and impurities in the working environment, causing the overall instability and failure of the thermal barrier coating. Based on the above problems of YSZ thermal barrier coating, in order to increase the thermal stability and chemical stability of the hot end component at super high temperature above 1600℃, an anti-ablation coating can be prepared on the surface of the thermal barrier coating, which can resist the erosion of high temperature flame and avoid the failure of the metal substrate due to high temperature damage.

[0005] ZrB2-based ultra-high temperature ceramic material has excellent properties such as high melting point, low theoretical density, high strength and hardness, high thermal conductivity and electrical conductivity, and can maintain good mechanical and chemical stability at high temperature, which can be applied to extreme temperature environments above 2000℃, becoming an ideal high-temperature protective coating material for current earth-to-space vehicles, hypersonic vehicles and rocket propulsion systems. However, current research has found that multi-layer coating of YSZ thermal barrier coating and ZrB2-based ultra-high temperature ceramic material cannot achieve good thermal matching due to the large difference in thermal expansion coefficient between YSZ coating and ZrB2-based coating, which makes the coating difficult to withstand the thermal stress during service at super high temperature and wide temperature range, and prone to coating peeling and other problems.

[0006] In view of the above, a multi-layer composite coating system is proposed to achieve various performance requirements of the coating. For example, the patent with publication number CN111500967A proposes a tungsten-copper alloy surface heat insulation / anti-ablation integrated composite coating and a preparation method thereof. From the surface of the tungsten-copper alloy, it includes a metal bonding layer, a ceramic inner layer, a ceramic transition layer, and a ceramic outer layer in sequence. The ceramic inner layer is an aluminum oxide layer, the ceramic transition layer is an aluminum oxide-rare earth zirconate layer, and the ceramic outer layer is a rare earth zirconate layer. The rare earth zirconate ceramic material used in the ceramic outer layer has low thermal conductivity, excellent heat insulation performance, and good anti-ablation performance. By setting a multi-layer gradient coating structure, the stress caused by thermal expansion mismatch is reduced, and the high-temperature service performance of the coating is improved. However, in the above scheme, the rare earth zirconate and aluminum oxide have the disadvantages of high brittleness, insufficient toughness, poor performance in anti-ultra-high-temperature oxidation and anti-ablation, etc., and are difficult to withstand extreme high temperatures exceeding 1600℃, rich oxygen, and severe high-temperature conditions such as airflow scouring.

[0007] Therefore, there is an urgent need for a thermal protection coating system with more outstanding high-temperature resistance performance. SUMMARY

[0008] The technical problems to be solved by the present application are:

[0009] In existing multi-layer composite heat insulation coatings, metal bonding layers, ceramic inner layers, ceramic transition layers, and ceramic outer layers are used in combination to improve the heat insulation, anti-ablation, and other performance of the coating. To further solve the problem of thermal expansion between multi-layer coatings, some research has proposed using rare earth zirconate ceramic material as the ceramic outer layer to reduce the stress caused by thermal expansion mismatch. However, rare earth zirconate ceramic has the problems of high brittleness, low toughness, poor resistance to high-low temperature cycle impact, insufficient anti-ablation ability, etc., making it difficult to be used in the field of aerospace, etc.

[0010] The technical scheme adopted by the present application is:

[0011] The present application provides a composite heat insulation coating including a metal bonding layer, a ceramic heat insulation layer, a ceramic oxygen barrier transition layer, and a ceramic anti-ablation layer stacked in layers. The metal bonding layer is close to the surface of the substrate to be coated. The ceramic heat insulation layer is a multi-element rare earth oxide doped YSZ coating, and the multi-element rare earth oxide is selected from two or more of CeO2, La2O3, Sm2O3, and Yb2O3.

[0012] Preferably, the preparation method of the multi-rare earth oxide doped YSZ powder is as follows: mixing YSZ powder, rare earth oxide powder, polyvinyl alcohol and deionized water, ball milling to form a slurry; and then performing spray drying to obtain the multi-rare earth oxide doped YSZ powder. Further, the spray drying process parameters are: inlet temperature of 220-230°C, outlet temperature of 110-120°C, and atomizer rotation speed of 20-30Hz.

[0013] Preferably, in the preparation process of the multi-rare earth oxide doped YSZ powder, the mass fraction of polyvinyl alcohol is 1-3%, the mass fraction of deionized water is 40-45%, and the rest is YSZ powder and rare earth oxide powder.

[0014] Preferably, the ceramic oxygen barrier transition layer is Yb3Al5O 12 .

[0015] Preferably, the ceramic ablation-resistant layer is ZrB2-SiC ultra-high temperature ceramic.

[0016] Preferably, the metal bonding layer is one or more of NiCrAlY, CoCrAlY or CoNiCrAlY.

[0017] The application also provides a preparation method of the composite thermal barrier coating as described above, comprising the following steps:

[0018] S1: sandblasting the surface of a substrate to be coated, and using an atmospheric plasma spraying process to spray NiCrAlY powder and / or CoCrAlY powder and / or CoNiCrAlY powder on the sandblasted surface to form a metal bonding layer;

[0019] S2: using an atmospheric plasma spraying process to spray multi-rare earth oxide doped YSZ powder on the surface of the metal bonding layer to form a ceramic thermal barrier layer;

[0020] S3: using an atmospheric plasma spraying process to spray Yb3Al5O 12 powder on the surface of the ceramic thermal barrier layer to form a ceramic oxygen barrier transition layer;

[0021] S4: using an atmospheric plasma spraying process to spray ZrB2-SiC ultra-high temperature ceramic powder on the surface of the ceramic oxygen barrier transition layer to form a ceramic ablation-resistant layer.

[0022] Preferably, the thicknesses of the metal bonding layer, the ceramic thermal barrier layer, the ceramic oxygen barrier transition layer and the ceramic ablation-resistant layer are 50-80μm, 80-150μm, 30-50μm and 80-150μm, respectively.

[0023] Preferably, the thermal expansion coefficients of the metal bonding layer, the ceramic thermal barrier layer, the ceramic transition layer and the ceramic ablation-resistant layer are 17.5x10-6 / K, 10.7×10 -6 / K, 7.8×10 -6 / K, 5.7×10 -6 / K.

[0024] Preferably, the NiCrAlY powder and / or CoCrAlY powder and / or CoNiCrAlY powder in the metal binder layer have a particle size of 30–50 μm; the multi-element rare earth oxide-doped YSZ powder has a particle size of 40–60 μm; and the Yb3Al5O3 powder in the ceramic oxygen barrier transition layer has a particle size of 40–60 μm. 12 The powder has a particle size of 40–60 μm; the ZrB2-SiC ultra-high temperature ceramic powder has a particle size of 40–60 μm.

[0025] Preferably, during the sandblasting process, corundum sand can be used as the abrasive, with an average particle size of 70–120 μm; the controlled pressure is 0.2–0.6 MPa, the sandblasting distance is 50–150 mm, and the sandblasting time is 5–15 min.

[0026] Preferably, the Yb3Al5O 12 The powder preparation method is as follows:

[0027] With a molar ratio of 3:4 to 6, Yb₂O₃ and Al₂O₃ powders were measured, mixed, ball-milled in anhydrous ethanol, dried, crushed, and sieved to obtain a Yb₂O₃ / Al₂O₃ mixed powder. Using a high-temperature solid-state reaction method, the Yb₂O₃ / Al₂O₃ mixed powder was calcined in air at high temperature to obtain pure phase Yb₃Al₅O₃. 12 Powder; then Yb3Al5O 12 Powder, polyvinyl alcohol, and deionized water were mixed, ball-milled, and then a slurry was prepared; this slurry was then spray-dried to obtain spherical Yb3Al5O. 12 Powder coating. Further, the spray drying process parameters are: inlet temperature 220–250℃, outlet temperature 100–120℃, and atomizer speed 20–30Hz.

[0028] Preferably, the Yb3Al5O 12 When powder, polyvinyl alcohol, and deionized water are mixed, the mass fraction is 1-2% polyvinyl alcohol, 40-45% deionized water, and the balance is Yb3Al5O. 12 powder.

[0029] Preferably, the preparation method of the ZrB2-SiC ultra-high temperature ceramic powder is as follows:

[0030] The zirconium boride powder, silicon carbide powder, polyvinyl alcohol and deionized water are uniformly mixed, ball milled, and made into a slurry; and then the ZrB2-SiC ultra-high temperature ceramic powder is obtained by spray drying. Further, the spray drying process parameters are: inlet temperature of 300-350 DEG C, outlet temperature of 100-150 DEG C, water pump speed of 40-60 r / min, and atomizer speed of 25-35 Hz.

[0031] Preferably, the ZrB2-SiC ultra-high temperature ceramic powder comprises 0.4-1% polyvinyl alcohol, 40-45% deionized water by mass fraction, and the balance of zirconium boride powder and silicon carbide powder.

[0032] Preferably, when the atmospheric plasma spraying process is used, Ar / N2 / H2 is used as the spraying gas, the control voltage is 50-60 V, the current is 350-400 A, and the spraying distance is 100-150 mm.

[0033] Preferably, in steps S1-S3, the gas flow rate Ar is controlled to be 30-105 L / min, N2 is 2-50 L / min, and H2 is 5-50 L / min; and in step S4, the gas flow rate Ar is controlled to be 94.4-103.8 L / min, N2 is 37.7-47.2 L / min, and H2 is 37.7-47.2 L / min.

[0034] The technical mechanism and beneficial effects adopted by the present application are:

[0035] In the present application, a metal bonding layer, a ceramic thermal insulation layer, a ceramic oxygen barrier transition layer and a ceramic ablation-resistant layer are sprayed in sequence on the surface of the substrate to be coated, i.e. a multi-layer gradient structure is adopted. Through reasonable selection and setting of the materials of each layer, the synergistic effect of the different high-temperature properties of the materials of each layer is utilized to improve the overall performance of the composite thermal insulation coating, which can withstand an ultra-high temperature environment of more than 1600 DEG C and achieve excellent high-temperature oxidation resistance, ablation resistance, thermal insulation and other properties; through the layer-by-layer change of the thermal conductivity and the thermal expansion coefficient of each layer, the thermal gradient can be adjusted to reduce the thermal stress caused by the mismatch of thermal expansion, solve the problem of easy peeling and failure of the coating in temperature sudden change, improve the service performance and life of the coating in high-low temperature service environment, and can be applied to extreme environments including hypersonic long-time flight, atmospheric reentry, transatmospheric flight and rocket propulsion system.

[0036] Specifically, the metal bonding layer can realize good bonding of the ceramic and the substrate. The ceramic thermal barrier layer adopts a multielement rare earth oxide to dope a traditional YSZ thermal barrier coating, the thermal conductivity of which is low, used to hinder the transmission of heat to the alloy substrate, and can improve the high-temperature oxidation resistance, ablation resistance, thermal insulation and other performances of the coating. The ceramic oxygen barrier transition layer is used to reduce the diffusion of oxygen to the inside of the coating and the metal substrate, and can improve the high-temperature oxidation resistance of the coating. The outermost ceramic ablation-resistant layer adopts a ZrB2-based coating doped with SiC as a ceramic surface layer, which has a melting point of more than 3000 DEG C, excellent ablation resistance, blocks oxygen erosion of the internal substrate, and protects the substrate from oxidation, and can be applied to high-temperature extreme environments above 1800 DEG C; according to the difference in the thermal expansion coefficients of the thermal barrier layer and the ablation-resistant layer, Yb3Al5O 12 As its transition layer, the diffusion of oxygen to the inside of the coating is reduced, and the thermal stress between the coatings is effectively relieved, improving the damage tolerance and overall high-temperature service life of the coating.

[0037] The composite thermal barrier coating system in the application has the advantages of adjustable thickness and controllable performance, and in practical application, the thickness and composition structure of each coating can be accurately controlled according to specific needs, has a wide range of practical application, and the coating preparation process is simple, the cost is relatively low, and is easy to realize large-scale production and practical application. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The figure is a comparison between the surface of the composite thermal barrier coating in Example 1 before and after ablation by an oxygen-ethyne flame.

[0039] Figure 2 The figure is a structure diagram of the composite thermal barrier coating in Example 1. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme of the embodiments of the application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0041] The application provides a composite thermal barrier coating, which is a multilayer gradient structure and comprises, from outside to inside along the surface of a substrate to be coated, a metal bonding layer, a ceramic thermal barrier layer, a ceramic oxygen barrier transition layer and a ceramic ablation-resistant layer.

[0042] In the application, the ceramic thermal insulation layer is a YSZ coating doped with multi-rare earth oxides, the multi-rare earth oxides are selected from two or more of CeO2, La2O3, Sm2O3 and Yb2O3, the thermal insulation performance and high-temperature oxidation resistance of the layer can be improved, and the high-temperature protection performance of the overall coating is improved; the metal bonding layer is one or more of NiCrAlY, CoCrAlY or CoNiCrAlY; the ceramic oxygen barrier transition layer is Yb3Al5O 12 ; the ceramic ablation-resistant layer is a ZrB2-SiC ultra-high-temperature ceramic material, the ZrB2-based ceramic material doped with SiC has excellent high-temperature ablation resistance and high-temperature oxidation resistance, and plays a significant thermal protection role in the process of bearing dynamic high-temperature airflow.

[0043] In the application, the thicknesses of the metal bonding layer, the ceramic thermal insulation layer, the ceramic oxygen barrier transition layer and the ceramic ablation-resistant layer are 50-80 μm, 80-150 μm, 30-50 μm and 80-150 μm, respectively.

[0044] In the application, the thermal expansion coefficients of the metal bonding layer, the ceramic thermal insulation layer, the ceramic oxygen barrier transition layer and the ceramic ablation-resistant layer are 17.5*10 -6 / K, 10.7*10 -6 / K, 7.8*10 -6 / K and 5.7*10 -6 / K, respectively. By gradually changing the thermal expansion coefficients, the problem of serious mismatch between the thermal expansion coefficients of the ceramic layer and the metal matrix is avoided, the thermal stress generated in the process of high-temperature service of the coating is reduced, and the problem of easy peeling of the coating in temperature sudden change is solved.

[0045] In the application, the preparation method of the composite thermal insulation coating comprises the following steps:

[0046] (1) sandblasting is performed on the surface of the to-be-coated substrate, the pressure is controlled to be 0.2-0.6 MPa, the sandblasting distance is 50-150 mm, and the sandblasting time is 5-15 min; then the metal bonding layer is sprayed on the sandblasted surface by using an atmospheric plasma spraying process;

[0047] (2) the multi-rare earth oxide doped YSZ powder is sprayed on the surface of the metal bonding layer by using an atmospheric plasma spraying process, and the ceramic thermal insulation layer is formed;

[0048] (3) the Yb3Al5O 12 powder is sprayed on the surface of the ceramic thermal insulation layer by using an atmospheric plasma spraying process, and the ceramic oxygen barrier transition layer is formed;

[0049] (4) the ZrB2-SiC ultra-high-temperature ceramic powder is sprayed on the surface of the ceramic oxygen barrier transition layer by using an atmospheric plasma spraying process, and the ceramic ablation-resistant layer is formed;

[0050] In the atmospheric plasma spraying process, Ar / N2 / H2 is used as the spraying gas, with the voltage controlled at 50–60V, the current at 350–400A, and the spraying distance at 100–150mm. When spraying the metal bonding layer, ceramic heat insulation layer, and ceramic oxygen barrier transition layer, the gas flow rates are controlled as follows: Ar 30–105L / min, N2 2–50L / min, and H2 5–50L / min. When spraying the ceramic ablation-resistant layer, the gas flow rates are controlled as follows: Ar 94.4–103.8L / min, N2 37.7–47.2L / min, and H2 37.7–47.2L / min.

[0051] In this invention, the abrasive can be corundum sand with an average particle size of 70–120 μm; the particle sizes of NiCrAlY powder, CoCrAlY powder, and CoNiCrAlY powder are all 30–50 μm; the particle size of YSZ powder doped with multi-element rare earth oxides is 40–60 μm; and the particle size of Yb3Al5O is... 12 The particle size of the powder is 40-60 μm, and the particle size of the ZrB2-SiC ultra-high temperature ceramic powder is 40-60 μm.

[0052] In this invention, Yb3Al5O 12 The powder preparation method is as follows:

[0053] Measure out the Yb₂O₃ and Al₂O₃ powders, mix them thoroughly, ball mill them in ethanol, dry them, crush them, and sieve them to obtain a Yb₂O₃ / Al₂O₃ mixed powder. Using a solid-state reaction method, place the Yb₂O₃ / Al₂O₃ mixed powder in air and calcine it at 1100–1200℃ for 1–5 hours to obtain pure phase Yb₃Al₅O₃. 12 Powder; then Yb3Al5O 12 Powder, polyvinyl alcohol, and deionized water were mixed, ball-milled, and then a slurry was prepared; this slurry was then spray-dried to obtain spherical Yb3Al5O. 12 Powder coating. Further, the spray drying process parameters are: inlet temperature 220–250℃, outlet temperature 100–120℃, and atomizer speed 20–30Hz.

[0054] Among them, Yb3Al5O 12 When powder, polyvinyl alcohol, and deionized water are mixed, the mass fraction is 1-2% polyvinyl alcohol, 40-45% deionized water, and the balance is Yb3Al5O. 12 powder.

[0055] The preparation method of YSZ powder doped with multi-element rare earth oxides in this invention is as follows:

[0056] Mixing YSZ powder, rare earth oxide powder, polyvinyl alcohol and deionized water, ball milling, making slurry; then through spray drying, get multi-rare earth oxide doped YSZ powder. Further, the spray drying process parameters are: inlet temperature is 220-230 DEG C, outlet temperature is 110-120 DEG C, atomizer speed is 20-30 Hz. According to mass fraction, multi-rare earth oxide doped YSZ powder includes 1-3% polyvinyl alcohol, 40-45% deionized water, the rest is YSZ powder and rare earth oxide powder.

[0057] In the application, the preparation method of ZrB2-SiC ultra-high temperature ceramic powder is as follows:

[0058] Mixing zirconium boride powder, silicon carbide powder, polyvinyl alcohol and deionized water, ball milling, making slurry; then through spray drying, get ZrB2-SiC ultra-high temperature ceramic powder. Further, the spray drying process parameters are: inlet temperature is 300-350 DEG C, outlet temperature is 100-150 DEG C, water pump speed is 40-60 r / min, atomizer speed is 25-35 Hz. According to mass fraction, ZrB2-SiC ultra-high temperature ceramic powder includes 0.4-1% polyvinyl alcohol, 40-45% deionized water, the rest is zirconium boride powder and silicon carbide powder.

[0059] <EMBODIMENT>

[0060] Example 1

[0061] Step 1: Prepare the alloy steel substrate, after washing with acetone, sandblast the surface to get the metal substrate to be used.

[0062] Step 2: Spray a layer of metal bonding layer with a thickness of about 70 μm on the metal substrate using NiCrAlY powder with an average particle size of 40 μm. The plasma spraying process and parameters of the NiCrAlY layer are as follows: gas flow Ar is 33 L / min, N2 is 3.3 L / min, H2 is 7 L / min; voltage is 60 V, current is 350 A, spraying distance is 100 mm, and spraying cycle number is 2 times.

[0063] Step 3: The purity of CeO2 powder, La2O3 powder and YSZ powder is 99.9%, and the particle size is about 2 μm. The molar fraction of CeO2, La2O3 and YSZ powder is 20 mol%, 1 mol% and 79 mol% respectively. The powders are uniformly mixed in a ZrO2 ceramic jar. Deionized water is added to control the solid solution ratio to about 42%. ZrO2 milling beads are added to control the ball-to-material ratio to about 1.5:1. Polyvinyl alcohol is added to control the mass of polyvinyl alcohol accounting for 2% of the total mass of the slurry. The slurry-filled ball mill jar is symmetrically placed in the ball mill, and the ball milling parameters are adjusted to 300 r / min, and the ball milling time is 10 h. The milled slurry is poured into a container jar, and spray granulation is carried out under the conditions of an inlet temperature of 225℃, an outlet temperature of 118℃, and an atomizer speed of 25 Hz. Finally, it is dried at 80℃ for 2 h to obtain CeO2-La2O3-YSZ composite powder with high sphericity, good flowability and suitable for thermal spraying.

[0064] Step 4: CeO2-La2O3-YSZ powder with an average particle size of 50 μm is used to spray a layer of CeO2-La2O3-YSZ composite ceramic thermal barrier layer with a thickness of about 120 μm on the surface of the metal bonding layer obtained in step 2. The plasma spraying process and parameters of the CeO2-La2O3-YSZ layer are as follows: gas flow Ar is 33 L / min, N2 is 3.3 L / min, H2 is 7 L / min; voltage is 60 V, current is 500 A, spraying distance is 100 mm, and spraying cycle number is 5 times.

[0065] Step 5: Yb2O3 and Al2O3 powders are used as starting materials, and are weighed and mixed according to a molar ratio of 3:5, ball milled in anhydrous ethanol, and the milled slurry is dried in an oven. The dried block is crushed, sieved through a 200 mesh sample sieve to obtain Yb2O3 / Al2O3 mixed powder. The mixed powder is calcined in air at 1150℃ for 2 h by solid phase reaction method to obtain pure phase Yb3Al5O 12 powder. The Yb3Al5O 12 powder, polyvinyl alcohol and deionized water are mixed and ball milled to prepare a slurry. In this mixing process, the mass fraction of polyvinyl alcohol is 1-2%, the mass fraction of deionized water is 40-45%, and the mass fraction of Yb3Al5O 12 powder is the rest. Then, spherical Yb3Al5O 12 spraying powder is obtained by spray drying. In the spray drying process, the inlet temperature is controlled at 235℃, the outlet temperature is controlled at 110℃, and the atomizer speed is controlled at 20-30 Hz.

[0066] Step 6: The average particle size of the spherical Yb3Al5O 12Spraying powder, spraying a layer of Yb3Al5O 12 oxygen barrier layer on CeO2-La2O3-YSZ with a thickness of about 40 μm 12 The plasma spraying process and parameters of the oxygen barrier layer are as follows: gas flow Ar is 33 L / min, N2 is 3.3 L / min, H2 is 7 L / min; voltage is 60 V, current is 500 A, spraying distance is 100 mm, and spraying cycle number is 5 times.

[0067] Step 7: ZrB2 powder with a purity of 99.99% and a particle size of about 2 μm and SiC ceramic powder prepared by self-propagating synthesis method are used; 80% ZrB2 powder and 20% SiC powder by mass fraction are respectively weighed and uniformly mixed in a ZrO2 ceramic jar; deionized water is added, and the solid solution ratio is controlled to be about 42%; ZrO2 milling beads are added, and the ball-to-material ratio is controlled to be about 1.5:1; polyvinyl alcohol is added, and the mass of polyvinyl alcohol accounts for 0.4% of the total mass of the slurry. The slurry-filled ball milling jars are symmetrically placed in pairs in the ball mill, and the ball milling parameters are adjusted to 300 r / min, and the ball milling time is 24 h; after ball milling, the ball-milled slurry is poured into a container jar, and under the conditions of an inlet temperature of 325 ℃, an outlet temperature of 125 ℃, a feed pump speed of 50 r / min, and an atomizer speed of 30 Hz, spray granulation is carried out; finally, drying at 80 ℃ for 2 h, ZrB2-SiC composite powder with high sphericity and good flowability suitable for thermal spraying is obtained.

[0068] Step 8: ZrB2-SiC composite powder with an average particle size of about 52 μm is used to spray a ZrB2-SiC ultra-high temperature ablation-resistant coating with a thickness of about 125 μm on the surface of the Yb3Al5O 12 oxygen barrier layer. The plasma spraying process and parameters of the ZrB2-SiC ultra-high temperature ablation-resistant coating are as follows: gas flow Ar is 98.4 L / min, N2 is 42.7 L / min, H2 is 42.7 L / min, voltage is 60 V, current is 500 A, spraying distance is 100 mm, and spraying cycle number is 12 times.

[0069] Example 2

[0070] The difference between this embodiment and Example 1 is that the metal bonding layer, the CeO2-La2O3-YSZ composite ceramic coating, the Yb3Al5O 12 oxygen barrier layer and the ZrB2-SiC ultra-high temperature ablation-resistant coating have thicknesses of 50 μm, 150 μm, 40 μm, and 150 μm, respectively.

[0071] Example 3

[0072] The difference between the present embodiment and embodiment 1 is that the metal bonding layer, the CeO2-La2O3-YSZ composite ceramic coating, the Yb3Al5O 12 The thickness of the oxygen barrier layer and the ZrB2-SiC ultra-high temperature ablation-resistant coating is 80 μm, 80 μm, 50 μm, 80 μm, respectively.

[0073] Example 4

[0074] The difference between the present embodiment and embodiment 1 is that the raw materials for the ceramic thermal insulation layer include Sm2O3 powder, Yb2O3 powder and YSZ powder, and the particle size and other parameters remain unchanged.

[0075] Example 5

[0076] The difference between the present embodiment and embodiment 1 is that the metal bonding layer uses CoCrAlY powder.

[0077] Example 6

[0078] The difference between the present embodiment and embodiment 1 is that the metal bonding layer uses CoNiCrAlY powder.

[0079] <Comparative Example>

[0080] Comparative Example 1

[0081] The difference between the present comparative example and embodiment 1 is that the ceramic thermal insulation layer uses an alumina layer, the ceramic oxygen barrier transition layer uses an alumina-rare earth zirconate layer, and the ceramic ablation-resistant layer uses a rare earth zirconate layer.

[0082] <Test Example>

[0083] Samples: Examples 1-6, Comparative Example 1

[0084] The above samples (5 test samples were randomly taken for each sample) were taken, and the thermal insulation, ablation resistance and other properties of the samples were determined, and the average value was taken as the result. The determination results are as follows in Table 1:

[0085] Table 1 Thermal insulation and other properties of samples

[0086]

[0087] The composite thermal insulation coating prepared in Examples 1-6 can have a room temperature bonding strength of about 40 MPa.

[0088] In addition, the ablation test of the composite heat-insulating coating is carried out by using oxygen-ethyne flame, and the surface temperature of the ablation coating and the back temperature of the alloy substrate are measured by using a laser infrared temperature measuring instrument, so as to test the oxidation and ablation performance of the composite heat-insulating coating in the environment of high temperature, oxygen-rich and airflow scouring. It is found that the surface temperature of the coating during the ablation test is about 1950℃, and the average temperature of the alloy substrate is about 785℃, which indicates that the composite heat-insulating coating has good heat-insulating performance.

[0089] The mass ablation rate of the composite heat-insulating coating after ablation for 300s can be as low as 8.06*10 -4 g / s and below, which is greatly reduced compared with the coating in Comparative Example 1; and as shown in Fig. 2, the ablation of the sample in Example 1 is carried out, the coating after ablation is kept intact and closely covers the surface of the substrate, and no obvious peeling phenomenon occurs. Figure 1 According to the ablation rate determination data, it can be illustrated that the composite heat-insulating coating has significant anti-ultra-high-temperature oxidation and ablation performance.

[0090] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A composite thermal barrier coating, characterized by, The ceramic heat insulation layer is a YSZ coating doped with multi-element rare earth oxides, the multi-element rare earth oxides being selected from multiple kinds of CeO2, La2O3, Sm2O3 and Yb2O3; The preparation method of the multi-element rare earth oxide doped YSZ powder is as follows: The YSZ powder, the rare earth oxide powder, polyvinyl alcohol and deionized water are uniformly mixed to form a slurry, and then ball-milling is performed; and then the multi-element rare earth oxide doped YSZ powder is obtained through spray drying; The preparation method of the composite heat insulation coating comprises the following steps: S1, sandblasting is performed on the surface of the substrate to be coated, and NiCrAlY powder and / or CoCrAlY powder and / or CoNiCrAlY powder is sprayed on the sandblasted surface to form a metal bonding layer with a thickness of 50-80 μm, the metal bonding layer being one or more of NiCrAlY, CoCrAlY or CoNiCrAlY; S2, multi-element rare earth oxide doped YSZ powder is sprayed on the surface of the metal bonding layer to form a ceramic heat insulation layer with a thickness of 80-150 μm; S4, ZrB2-SiC ultra-high temperature ceramic powder is sprayed on the surface of the ceramic oxygen barrier transition layer to form a ZrB2-SiC ceramic ablation-resistant layer with a thickness of 80-150 μm. S3 Spraying Yb3Al5O 12 powder to form a 30-50 μm thick Yb3Al5O 12 ceramic oxygen barrier transition layer; In the preparation process of the multi-element rare earth oxide doped YSZ powder, the polyvinyl alcohol accounts for 1-3% by mass fraction, the deionized water accounts for 40-45% by mass fraction, and the balance is YSZ powder and rare earth oxide powder.

2. The composite thermal barrier coating of claim 1, wherein, The preparation method of the composite heat insulation coating comprises the following steps:

3. A method for the production of a composite thermal barrier coating as claimed in claim 1 or 2, characterized in that S1, sandblasting is performed on the surface of the substrate to be coated, and NiCrAlY powder and / or CoCrAlY powder and / or CoNiCrAlY powder is sprayed on the sandblasted surface to form a metal bonding layer with a thickness of 50-80 μm, the metal bonding layer being one or more of NiCrAlY, CoCrAlY or CoNiCrAlY; S2, multi-element rare earth oxide doped YSZ powder is sprayed on the surface of the metal bonding layer to form a ceramic heat insulation layer with a thickness of 80-150 μm; S4, ZrB2-SiC ultra-high temperature ceramic powder is sprayed on the surface of the ceramic oxygen barrier transition layer to form a ZrB2-SiC ceramic ablation-resistant layer with a thickness of 80-150 μm. S3 again using atmospheric plasma spraying process in the ceramic thermal barrier layer surface spraying Yb3Al5O 12 powder, forming a ceramic oxygen barrier transition layer; The particle size of the NiCrAlY powder and / or CoCrAlY powder and / or CoNiCrAlY powder in the metal bonding layer is 30-50 μm; 4. The method of claim 3, wherein the composite thermal barrier coating is prepared by a method comprising: The particle size of the multi-element rare earth oxide doped YSZ powder is 40-60 μm; The particle size of the ZrB2-SiC ultra-high temperature ceramic powder is 40-60 μm. Yb3Al5O in ceramic oxygen barrier transition layer 12 Powder, particle size 40-60 μm; ​

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