Thermal barrier coating based on slurry dipping-sintering process and preparation method thereof
The thermal barrier coating was prepared by slurry impregnation-sintering process, which solved the problems of high cost and low consistency in the existing technology, and achieved the reduction of equipment cost and the improvement of process stability. The coating exhibited excellent thermal shock adaptability and thermal cycling resistance.
Patent Information
- Application Number
- CN202610075265.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-20
- Publication Date
- 2026-04-21
AI Technical Summary
Existing methods for preparing thermal barrier coatings have high equipment costs and narrow process windows, resulting in high production costs and poor quality consistency, which limits their large-scale application.
A thermal barrier coating with uniform structure and controllable thickness is prepared by using a slurry impregnation-sintering process to form a porous ceramic layer on the surface of the metal bonding layer, combined with multiple impregnation-pulling, degreasing and high-temperature sintering.
It reduces equipment investment costs by 50%-70%, reduces power consumption by 40%-60%, improves process stability and material utilization, and the coating exhibits good thermal shock adaptability and resistance to thermal cycling failure.
Smart Images
Figure CN121896635A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-temperature thermal protective coating technology, and in particular to a thermal barrier coating based on a slurry impregnation-sintering process and its preparation method. Background Technology
[0002] Thermal barrier coatings are widely used in high-temperature components such as aero-engines and gas turbines, effectively reducing substrate operating temperatures and extending their service life. Existing thermal barrier ceramic coatings are mostly prepared using methods such as plasma spraying (e.g., APS) or physical vapor deposition (e.g., EB-PVD), which generally suffer from high equipment costs and narrow process windows. This directly results in high coating production costs and poor quality consistency, severely restricting their large-scale engineering applications and raising the technical entry barrier for the industry. Therefore, developing a thermal barrier ceramic coating preparation method with strong process adaptability, controllable structure, and lower equipment requirements has significant engineering application value and academic significance. Summary of the Invention
[0003] To overcome the technical defects of high process complexity and poor structural consistency in the existing technology, this invention provides a thermal barrier coating based on slurry impregnation-sintering process and its preparation method. By combining slurry forming with segmented heat treatment, the thickness and pore structure of the ceramic layer can be controlled.
[0004] This invention provides a thermal barrier coating based on a slurry impregnation-sintering process. The thermal barrier coating is disposed on the surface of a high-temperature alloy substrate and includes a metal bonding layer and a ceramic layer. The metal bonding layer is located between the high-temperature alloy substrate and the ceramic layer. The ceramic layer is obtained by repeatedly impregnating and pulling a high-temperature resistant ceramic slurry, drying, segmented degreasing, and high-temperature sintering. The ceramic layer is a continuously formed porous ceramic layer, which forms a mechanical interlocking bond with the metal bonding layer.
[0005] Preferably, the high-temperature resistant ceramic slurry includes high-temperature resistant ceramic powder, organic binder, and organic solvent.
[0006] Preferably, the high-temperature resistant ceramic powder is selected from one or more of zirconia-based ceramics, rare earth zirconate ceramics, and rare earth oxide ceramics.
[0007] Preferably, the organic binder is one or more of polyvinyl butyral, polyvinyl alcohol, and acrylic resin.
[0008] Preferably, the ceramic layer has a uniformly distributed porous structure with a thickness of 50–200 μm and a porosity of 10–30%.
[0009] This invention also discloses a method for preparing a thermal barrier coating based on a slurry impregnation-sintering process, used to prepare the thermal barrier coating described in this invention, characterized by the following steps:
[0010] S1. A metal bonding layer is deposited on the surface of a high-temperature alloy substrate;
[0011] S2. Mix and disperse high-temperature resistant ceramic powder, organic binder and organic solvent to prepare a ceramic slurry with film-forming properties;
[0012] S3. The ceramic slurry is coated onto the surface of the metal bonding layer by dip-lifting method, and a ceramic green body layer is formed by repeated dip-lifting.
[0013] S4. The ceramic green body layer is subjected to degreasing and high-temperature sintering treatment in sequence to form a thermal barrier coating with a porous structure.
[0014] Preferably, in step S4, the degreasing treatment temperature is 200–500°C, and the high-temperature sintering treatment temperature is 1000–1400°C.
[0015] Preferably, in step S3, the number of dip-lifting cycles is 2 to 8.
[0016] Compared with existing technologies, the technical solution provided by this invention has the following technical advantages: The thermal barrier coating preparation method of this invention can form a uniformly structured and controllable thickness thermal barrier ceramic layer on the surface of the metal bonding layer, resulting in a coating porosity within a reasonable range of 10%-30% and exhibiting good thermal shock adaptability. The process flow of this invention is simple. The ceramic layer is prepared using a slurry method, eliminating the need for high-energy power supplies and spray gun / evaporation source systems that rely on APS or EB-PVD for ceramic layer preparation. Compared to the technical route that completely uses APS / EB-PVD to prepare metal and ceramic layers, equipment investment costs can be reduced by approximately 50%-70%, and energy consumption per unit area of coating preparation process can be reduced by approximately 40%-60%. Simultaneously, this method simplifies process steps, requires less technical expertise from operators, and significantly reduces the need for spraying parameter adjustment and repeated trial production, thereby reducing labor costs and improving process stability. Because the slurry method has a high material utilization rate, the effective utilization rate of ceramic powder is significantly higher than that of traditional spraying processes, further reducing the material cost per unit thickness of the ceramic layer. The thermal barrier coating prepared by the above method exhibits good structural stability in thermal shock tests and can withstand no less than 30 thermal shock cycles, demonstrating excellent resistance to thermal cycling failure. Attached Figure Description
[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a cross-sectional schematic diagram of a thermal barrier coating based on a slurry impregnation-sintering process according to a certain embodiment of the present invention;
[0020] Figure 2 This is a microscopic morphology image of the YSZ thermal barrier coating surface prepared in Example 1 of this invention;
[0021] Figure 3 This is a cross-sectional microstructure diagram of the YSZ thermal barrier coating prepared in Example 1 of this invention;
[0022] Figure 4 The image shows the macroscopic morphology of the YSZ thermal barrier coating prepared in Example 1 of this invention after 36 thermal shock cycles from 1050°C to room temperature.
[0023] Figure 5 This is a macroscopic view of the surface of the BMT thermal barrier coating prepared in Example 2 of this invention;
[0024] Figure 6 This is a microscopic morphology image of the BMT thermal barrier coating prepared in Example 2 of this invention;
[0025] Figure 7 This is a cross-sectional microstructure diagram of the BMT thermal barrier coating prepared in Example 2 of this invention. Detailed Implementation
[0026] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.
[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.
[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0029] Example 1
[0030] In Example 1, a thermal barrier coating based on a slurry impregnation-sintering process and its preparation method are disclosed. The thermal barrier coating is disposed on the surface of a high-temperature alloy substrate and includes a metal bonding layer and a ceramic layer, with the metal bonding layer located between the high-temperature alloy substrate and the ceramic layer. The ceramic layer is prepared by a ceramic slurry formulated with yttrium-stabilized zirconium oxide (YSZ), polyvinyl butyral (PVB), and an organic solvent (anhydrous ethanol), which is subjected to multiple impregnation-pulling forming, drying, segmented debinding, and high-temperature sintering to form a porous thermal barrier coating ceramic layer with a porous structure.
[0031] Based on the above embodiments, in a preferred embodiment, the metal bonding layer is obtained by plasma spraying CoNiCrAlY powder with a particle size of 10-45 μm onto the surface of a high-temperature alloy substrate. The mass fraction of the composition of the CoNiCrAlY metal bonding layer is: 38.5% Co, 32% Ni, 21% Cr, 8% Al, and 0.5% Y. The thickness of the CoNiCrAlY metal bonding layer is 100 μm.
[0032] In a preferred embodiment, based on the above embodiments, the method for preparing the ceramic slurry is as follows:
[0033] (a1) Mix YSZ powder and PVB powder at a mass ratio of 23.5:1.5;
[0034] (a2) The mixed powder obtained in step (a1) is mechanically ball-milled with anhydrous ethanol at a solid-liquid mass ratio of 1:3. The mass ratio of the grinding balls to the mixed powder in step (a1) is 4:1. The grinding balls are ZrO2 balls with diameters of 10 mm, 8 mm and 5 mm. The ball milling speed is 300 rpm and the ball milling time is 3 h.
[0035] In this embodiment, the specific preparation method of the YSZ-CoNiCrAlY thermal barrier coating includes the following steps:
[0036] (b1) GH3128 nickel-based high-temperature alloy was selected as the high-temperature alloy matrix. The surface of the high-temperature alloy matrix to be sprayed was cleaned with acetone, an easily volatile organic solvent. The surface to be sprayed was roughened by sandblasting with 24-mesh white corundum sand at a pressure of 0.5 MPa to achieve a roughness of 3~5 μm. Then, dry compressed air was used to blow away the sand particles and dust adhering to the roughened surface.
[0037] (b2) An atmospheric plasma spraying (APS) technique was used to prepare a CoNiCrAlY metal bonding layer on the surface of the high-temperature alloy substrate after the first step treatment. The spraying parameters were as follows: the spraying current was set to 550–650 A, the flow rate of the main gas Ar was maintained at 40–60 L / min, the flow rate of the auxiliary gas He was 6–8 L / min, the flow rate of the carrier gas Ar was 5–7 L / min, the powder feed rate was 30–50 g / min, the spraying distance was controlled at 70–80 mm, the preheating temperature of the high-temperature alloy substrate was maintained at 50–150 °C, and the thickness of the sprayed CoNiCrAlY metal bonding layer was approximately 80 μm.
[0038] (b3) A YSZ ceramic layer was prepared on the surface of the CoNiCrAlY metal bonding layer using a slurry preparation technique. The slurry obtained in step (a2) was applied to the surface of the metal bonding layer obtained in step (b2) by impregnation.
[0039] (b4) Place the sample obtained in step (b3) in a well-ventilated and dry place to air dry for 24 h;
[0040] (b5) The sample obtained in step (b4) is subjected to heat treatment to sinter it. The heat treatment process is carried out in a tube furnace, heating to 300℃ at a heating rate of 5℃ / min and holding for 2 hours, then heating to 1200℃ at a heating rate of 5℃ / min and holding for 3 hours, and then cooling to room temperature at a cooling rate of 5℃ / min. The thickness of the YSZ ceramic layer is about 100μm and the porosity is about 12.6%. After steps (b1)-(b5) are completed, the YSZ-CoNiCrAlY thermal barrier coating is obtained.
[0041] The surface morphology, cross-sectional structure, and thermal shock performance of the YSZ-CoNiCrAlY thermal barrier coating prepared in this embodiment were tested.
[0042] The surface morphology of the YSZ-CoNiCrAlY thermal barrier coating was observed using a scanning electron microscope. Figure 2 The surface morphology of the prepared thermal barrier coating is shown. It can be seen that the YSZ ceramic layer prepared by the slurry method has a smooth and dense surface with tight particle bonding, exhibiting the best sintering densification effect.
[0043] The cross-sectional microstructure of the YSZ-CoNiCrAlY thermal barrier coating was observed using a scanning electron microscope. Figure 3 The cross-sectional microstructure of the prepared thermal barrier coating shows that the YSZ ceramic layer prepared by the slurry method exhibits a porous layered structure, composed of partially sintered particle aggregates, and containing through or closed micropores. The substrate, binder layer, and ceramic layers are well bonded, and no obvious defects such as cracks, pores, or through cracks were observed.
[0044] The thermal shock resistance of the YSZ-CoNiCrAlY thermal barrier coating was tested using the water quenching method. Specifically, the prepared sample was placed in a tube at 1050 °C for 10 min, then quickly removed and quenched in water at 20 °C. After the water surface calmed, the sample was removed and dried, completing one thermal shock test. This process was repeated until the coating peeled off more than 10%. The number of thermal shocks was recorded, and the number of thermal shocks was used as the basis for evaluating the coating's thermal shock resistance.
[0045] Tests showed that the prepared thermal barrier coating peeled off 10% of its surface area after 36 thermal shock cycles. Figure 4 Comparison of the macroscopic morphology of the thermal barrier coating prepared according to an embodiment of the present invention and after 36 thermal shock cycles.
[0046] Example 2
[0047] The high-temperature resistant ceramic powder in Example 1 was replaced with composite perovskite ceramic Ba(Mg) 1 / 3 Ta 2 / 3 O3 powder can still produce a structurally stable thermal barrier coating ceramic layer.
[0048] Example 2 discloses a thermal barrier coating based on a slurry impregnation-sintering process and its preparation method. The thermal barrier coating is disposed on the surface of a high-temperature alloy substrate and includes a metal bonding layer and a ceramic layer, with the metal bonding layer located between the high-temperature alloy substrate and the ceramic layer; the ceramic layer is composed of Ba(Mg)₂... 1 / 3 Ta 2 / 3 A ceramic slurry prepared from O3 (BMT), polyvinyl butyral (PVB) and an organic solvent (anhydrous ethanol) is subjected to multiple impregnation and pulling processes, drying, segmental degreasing, and high-temperature sintering to form a porous thermal barrier coating ceramic layer with a porous structure.
[0049] Based on the above embodiments, in a preferred embodiment, the metal bonding layer is obtained by plasma spraying CoNiCrAlY powder with a particle size of 10-45 μm onto the substrate surface. The mass fraction of the composition of the CoNiCrAlY metal bonding layer is: 38.5% Co, 32% Ni, 21% Cr, 8% Al, and 0.5% Y. The thickness of the CoNiCrAlY metal bonding layer is 100 μm.
[0050] In a preferred embodiment, based on the above embodiments, the method for preparing the ceramic slurry is as follows:
[0051] (c1) Mix BMT powder and PVB powder at a mass ratio of 23.5:1.5;
[0052] (c2) The mixed powder obtained in step (c1) is mechanically ball-milled with anhydrous ethanol at a solid-liquid mass ratio of 1:3. The mass ratio of the grinding balls to the mixed powder in step (c1) is 4:1. The grinding balls are ZrO2 balls with diameters of 10 mm, 8 mm and 5 mm. The ball milling speed is 300 rpm and the ball milling time is 3 h.
[0053] In this embodiment, the specific preparation method of the BMT-CoNiCrAlY thermal barrier coating includes the following steps:
[0054] (d1) GH3128 nickel-based high-temperature alloy was selected as the high-temperature alloy matrix. The matrix surface to be sprayed was cleaned with volatile organic solvent acetone. The surface to be sprayed was roughened by sandblasting with 24-mesh white corundum sand at a pressure of 0.5 MPa to achieve a roughness of 3~5 μm. Then, dry compressed air was used to blow away the sand particles and dust adhering to the roughened surface.
[0055] (d2) An atmospheric plasma spraying (APS) technique was used to prepare a CoNiCrAlY metal bonding layer on the surface of the high-temperature alloy substrate after the first step treatment. The spraying parameters were as follows: the spraying current was set to 550–650 A, the flow rate of the main gas Ar was maintained at 40–60 L / min, the flow rate of the auxiliary gas He was 6–8 L / min, the flow rate of the carrier gas Ar was 5–7 L / min, the powder feed rate was 30–50 g / min, the spraying distance was controlled at 70–80 mm, the preheating temperature of the high-temperature alloy substrate was maintained at 50–150 °C, and the thickness of the sprayed CoNiCrAlY metal bonding layer was approximately 80 μm.
[0056] (d3) A BMT ceramic layer was prepared on the surface of the CoNiCrAlY metal bonding layer using a slurry preparation technique. The slurry obtained in step (c2) was applied to the surface of the metal bonding layer obtained in step (d2) by impregnation.
[0057] (d4) Place the sample obtained in step (b3) in a well-ventilated and dry place to air dry for 24 h;
[0058] (d5) The sample obtained in step (d4) is subjected to heat treatment to sinter it. The heat treatment process is carried out in a tube furnace, heating to 300℃ at a heating rate of 5℃ / min and holding for 2 hours, then heating to 1200℃ at a heating rate of 5℃ / min and holding for 3 hours, and then cooling to room temperature at a cooling rate of 5℃ / min. The thickness of the BMT ceramic layer is approximately 60 μm, and the porosity is approximately 19.1%. After steps (d1)-(d5) are completed, the BMT-CoNiCrAlY thermal barrier coating is obtained.
[0059] The surface morphology and cross-sectional microstructure of the BMT-CoNiCrAlY thermal barrier coating prepared in this embodiment were observed.
[0060] The surface morphology of the BMT-CoNiCrAlY thermal barrier coating was observed using a scanning electron microscope. Figure 5 This is a macroscopic view of the surface of the prepared thermal barrier coating. Figure 6 The image shows the microstructure of the prepared thermal barrier coating. It is evident that the BMT thermal barrier coating prepared by the slurry method exhibits continuous overall coverage and good density, with no obvious through-cracks or large-scale defects observed on the coating surface. The coating surface is composed of fine and uniformly distributed ceramic particles, with tight bonding between the particles, exhibiting typical morphological characteristics of sintered ceramic surfaces.
[0061] The cross-sectional microstructure of the BMT-CoNiCrAlY thermal barrier coating was observed using a scanning electron microscope. Figure 7 The cross-sectional microstructure of the prepared thermal barrier coating shows that the interface between the BMT thermal barrier coating and the underlying metal bonding layer is clear and continuous. No obvious delamination, interface cracks or pore enrichment were observed, indicating that the coating and the substrate have a good interfacial bonding state.
[0062] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.
Claims
1. A thermal barrier coating based on a slurry impregnation-sintering process, wherein the thermal barrier coating is disposed on the surface of a high-temperature alloy substrate, characterized in that, It includes a metal bonding layer and a ceramic layer. The metal bonding layer is located between the high-temperature alloy substrate and the ceramic layer. The ceramic layer is made by repeatedly impregnating and pulling high-temperature resistant ceramic slurry, drying, degreasing in stages and sintering at high temperature. The ceramic layer is a continuously formed porous ceramic layer, which forms a mechanical interlocking bond with the metal bonding layer.
2. The thermal barrier coating based on slurry impregnation-sintering process according to claim 1, characterized in that, High-temperature resistant ceramic slurry includes high-temperature resistant ceramic powder, organic binder, and organic solvent.
3. The thermal barrier coating based on the slurry impregnation-sintering process according to claim 2, characterized in that, The high-temperature resistant ceramic powder is selected from one or more of zirconia-based ceramics, rare earth zirconate ceramics, and rare earth oxide ceramics.
4. The thermal barrier coating based on the slurry impregnation-sintering process according to claim 2, characterized in that, The organic binder is one or more of polyvinyl butyral, polyvinyl alcohol, and acrylic resin.
5. The thermal barrier coating based on a slurry impregnation-sintering process according to any one of claims 1-4, characterized in that, The ceramic layer has a uniformly distributed porous structure with a thickness of 50–200 μm and a porosity of 10–30%.
6. A method for preparing a thermal barrier coating based on a slurry impregnation-sintering process, used to prepare the thermal barrier coating of claim 5, characterized in that, The steps are as follows: S1. A metal bonding layer is deposited on the surface of a high-temperature alloy substrate; S2. Mix and disperse high-temperature resistant ceramic powder, organic binder and organic solvent to prepare a ceramic slurry with film-forming properties; S3. The ceramic slurry is coated onto the surface of the metal bonding layer by dip-lifting, and a ceramic green body is formed by repeated dip-lifting. S4. The ceramic green body layer is subjected to degreasing and high-temperature sintering treatment in sequence to form a thermal barrier coating with a porous structure.
7. The method for preparing a thermal barrier coating based on a slurry impregnation-sintering process according to claim 6, characterized in that, In step S3, the dipping and lifting process is repeated 2 to 8 times.
8. The method for preparing a thermal barrier coating based on a slurry impregnation-sintering process according to claim 7, characterized in that, In step S4, the degreasing treatment temperature is 200–500℃, and the high-temperature sintering treatment temperature is 1000–1400℃.