Thermal protection coating for nickel-based high-temperature alloys and preparation method thereof

Abstract

The present invention relates to a coating for thermal protection of nickel-based high-temperature alloys and a preparation method thereof, wherein the coating is composed of a bonding layer, a transition layer and a ceramic layer; wherein the bonding layer is NiCoGrAlYSi; the transition layer is (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7; the ceramic layer is (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1‑x Ce x )2O7, of which 0

Description

Technical Field

[0001] The present invention relates to the technical field of protective coatings, and in particular to a coating for thermal protection of nickel-based high-temperature alloys and a preparation method thereof. Background Art

[0002] Nickel-based superalloys exhibit excellent creep and fatigue resistance at operating temperatures approaching 80-90% of the alloy's melting point, while also offering excellent structural stability, oxidation resistance, and corrosion resistance. Ni-W-Mo superalloys offer high plasticity, high creep strength, and excellent oxidation resistance, as well as excellent properties for stamping and welding. Nickel-based superalloys, such as GH3128, are widely used in combustion chamber components, turbine engine combustion chamber parts, afterburner chambers, and other hot-end structures. Protected by YSZ-based thermal barrier coatings, nickel-based superalloy high-temperature structural components can operate at temperatures up to 1200°C.

[0003] As engines evolve toward higher thrust-to-weight ratios, higher flow rates, and higher thermal efficiency, the V2500 aircraft engine's combustion gas temperature exceeds 1400°C, reaching 1700°C. When the hot-end component temperature exceeds 1250°C, the YSZ coating undergoes phase transition instability, increasing the sintering rate and causing a sharp increase in interfacial thermal stress, leading to coating spalling and failure of the hot-end component. Furthermore, the relatively high thermal conductivity of the YSZ coating limits its insulation effectiveness within a certain thickness range. Therefore, it is necessary to develop a new coating to replace YSZ to meet the thermal shock protection requirements of nickel-based superalloy substrates subjected to temperatures of 1400°C.

[0004] At present, the thermal protection solutions applied to nickel-based high-temperature alloys are mainly concentrated in the YSZ system modification, pyrochlore structure R2Zr2O7 series (La2Zr2O7, Gd2Zr2O7), perovskite structure series (La(Al 1 / 4 Mg 1 / 2 Ta 1 / 4 )O3、Ba(Mg 1 / 3 Ta 2 / 3 )O3). However, its operating temperature is still limited to below 1200℃, which makes it difficult to meet the protection requirements of nickel-based high-temperature alloy substrates under thermal shock at 1400℃. Summary of the Invention

[0005] The main purpose of the present invention is to provide a coating for thermal protection of nickel-based high-temperature alloys and a preparation method thereof. The technical problem to be solved is to overcome the shortcomings of existing coatings and achieve the thermal protection requirements of nickel-based high-temperature alloy substrates under 1400°C thermal shock.

[0006] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. According to the present invention, a coating for thermal protection of nickel-based high-temperature alloys is provided, which is composed of a bonding layer, a transition layer and a ceramic layer stacked in sequence; wherein,

[0007] The bonding layer is NiCoGrAlYSi;

[0008] The transition layer is (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7;

[0009] The ceramic layer is (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7, of which 0 <x≤0.4。

[0010] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0011] Preferably, in the aforementioned coating for thermal protection of nickel-based high-temperature alloys, the thickness of the bonding layer is 0.1 to 0.3 mm; the thickness of the transition layer is 0.15 to 0.3 mm; and the thickness of the ceramic layer is 0.2 to 0.5 mm.

[0012] The purpose of the present invention and the solution to its technical problems are also achieved by adopting the following technical solutions. According to the present invention, a method for preparing a coating for thermal protection of nickel-based high-temperature alloys is proposed, which comprises:

[0013] Pretreating the nickel-based high-temperature alloy substrate;

[0014] The NiCoGrAlYSi bonding layer was prepared on the surface of the pretreated nickel-based high-temperature alloy substrate by using the supersonic flame spraying method;

[0015] The atmospheric plasma spraying method was used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer;

[0016] The atmospheric plasma spraying method was used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 ceramic layer, where 0 <x≤0.4。

[0017] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0018] Preferably, the aforementioned coating for thermal protection of nickel-based high-temperature alloys, wherein the pretreatment includes: first cleaning the nickel-based high-temperature alloy substrate with alkaline solution, then ultrasonically cleaning it with deionized water, and after drying, roughening the substrate surface.

[0019] Preferably, in the aforementioned coating for thermal protection of nickel-based high-temperature alloys, the alkali solution is 40 to 60 g / L of KOH;

[0020] After roughening treatment, the roughness of the substrate surface is 3μm≤Ra≤7μm.

[0021] Preferably, in the aforementioned coating for thermal protection of nickel-based high-temperature alloys, the conditions of the supersonic flame spraying method are: current 1700-1900A, main gas flow 10-20SCFH, and powder feeding rate 3.0-5.0g / min.

[0022] Preferably, the aforementioned coating for thermal protection of nickel-based high-temperature alloys is prepared on the bonding layer by atmospheric plasma spraying (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer, comprising:

[0023] First, the bonding layer is preheated by a plasma flame method at a temperature of 100 to 200°C; then, the bonding layer is prepared by an atmospheric plasma spraying method (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer; its preparation conditions are: spraying current 700~900A, main gas Ar flow rate 90~120SCFH, auxiliary gas H2 flow rate 10~25SCFH, powder feeding rate 10~40g / min.

[0024] Preferably, the aforementioned coating for thermal protection of nickel-based high-temperature alloys is prepared on the bonding layer by atmospheric plasma spraying (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer, first (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 agglomerate powder is sieved and dried, the sieving mesh size is -170 mesh to +500 mesh; the drying temperature is 120°C and the time is 2 to 8 hours.

[0025] Preferably, the above-mentioned coating for thermal protection of nickel-based high-temperature alloys is prepared by atmospheric plasma spraying (Gd 0.2 Yb 0.2 Y0.6 )2(Zr 1-x Ce x )2O7 ceramic layer, where 0 < x ≤ 0.4, and its preparation conditions are: spraying current 800 - 950 A, main gas Ar flow rate 100 - 120 SCFH, auxiliary gas H2 flow rate 10 - 25 SCFH, powder feeding rate 10 - 20 g / min.

[0026] Preferably, for the coating for thermal protection of nickel - based superalloys described above, in which when preparing the (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 ceramic layer by atmospheric plasma spraying method on the transition layer, first 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 agglomerate powder is sieved and dried. The mesh number of the sieving is - 200 mesh to + 500 mesh; the drying temperature is 120 °C and the time is 2 - 8 h.

[0027] Preferably, for the coating for thermal protection of nickel - based superalloys described above, the thickness of the bonding layer is 0.1 - 0.3 mm; the thickness of the transition layer is 0.15 - 0.3 mm; the thickness of the ceramic layer is 0.2 - 0.5 mm.

[0028] By the above - mentioned technical solution, the coating for thermal protection of nickel - based superalloys of the present invention has at least the following advantages:

[0029] 1. The coating for thermal protection of nickel - based superalloys provided by the present invention consists of a NiCoGrAlYSi bonding layer, a (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer and a (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 (0 < x ≤ 0.4) ceramic layer. Its service temperature can reach 1400 °C. At the same time, its thermal shock resistance is good and the heat insulation effect is relatively prominent.

[0030] 2. The heat insulation effect of the thermal protection coating prepared by the present invention is relatively high. When controlling the hot - side temperature at 1400 °C, the thermal protection coating can achieve a temperature drop of nearly 300 °C, and can achieve the thermal protection of nickel - based superalloys.

[0031] 3. The present invention mainly adopts supersonic flame spraying and atmospheric plasma spraying for preparation. This process has low cost. In addition, the size of the nickel-based high-temperature alloy substrate sample is not restricted and has a wide range of applications.

[0032] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic structural diagram of a coating for thermal protection of nickel-based high-temperature alloys proposed in an embodiment of the present invention is shown;

[0034] Figure 2 The figure shows the appearance of the thermal protective coating sample prepared in Example 1 of the present invention;

[0035] Figure 3 The cross-sectional microstructure of the thermal protective coating prepared in Example 1 of the present invention is shown;

[0036] Figure 4 The figure shows the heat insulation effect of the thermal protective coating prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0037] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with the accompanying drawings and preferred embodiments, provides a detailed description of the specific implementation, structure, features, and effectiveness of the coating for thermal protection of nickel-based superalloys proposed in accordance with the present invention. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0038] First, the exclusive right is introduced and described in order according to its structure.

[0039] like Figure 1 As shown, an embodiment of the present invention provides a coating for thermal protection of nickel-based high-temperature alloys, which is composed of a bonding layer 2, a transition layer 3 and a ceramic layer 4 stacked in sequence; wherein,

[0040] The bonding layer 2 is NiCoGrAlYSi;

[0041] The transition layer 3 is (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7;

[0042] The ceramic layer 4 is (Gd 0.2 Yb0.2 Y 0.6 )2(Zr 1-x Ce x )2O7, where 0 < x ≤ 0.4.

[0043] Furthermore, the thickness of the bonding layer 2 is 0.1 - 0.3 mm; preferably 0.2 mm;

[0044] The thickness of the transition layer 3 is 0.15 - 0.3 mm; preferably 0.2 mm;

[0045] The thickness of the ceramic layer 4 is 0.2 - 0.5 mm; preferably 0.3 mm.

[0046] The coating of the present application can enhance the heat insulation effect of the nickel-based superalloy substrate. In this coating, the ceramic layer mainly plays the role of heat insulation. However, there is a large difference in the thermal expansion coefficients between the substrate metal and the ceramic layer, and there is an obvious stress mismatch between them. The bonding layer has a thermal expansion coefficient similar to that of the substrate material, and the bonding layer NiCoGrAlYSi slows down the sudden change in the thermal expansion coefficient between the nickel-based superalloy substrate and the ceramic layer (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7(0 < x ≤ 0.4), reducing the thermal stress at the interface and thus improving the bonding strength between layers. The ceramic layer is bonded to the substrate by means of the bonding layer between the substrate and the ceramic layer. The transition layer (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 is located between the ceramic layer (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7(0 < x ≤ 0.4) and the bonding layer NiCoGrAlYSi, eliminating the residual stress caused by the mismatch in the thermal expansion coefficient between the bonding layer / ceramic layer. The transition layer can effectively slow down the thermal stress in the coating, hinder the formation and expansion of cracks in the coating, and thus improve the thermal shock resistance of the coating.

[0047] Although the thicker the coating, the better its heat insulation effect, but if the coating is too thick, the firmness of the coating will be reduced. Therefore, it is necessary to comprehensively consider to determine the thickness of the coating.

[0048] As Figure 1 shown, the bonding layer 2, the transition layer 3 and the ceramic layer 4 of the coating for thermal protection of nickel-based superalloys are sequentially laminated on the surface of the nickel-based superalloy substrate 1, where the bonding layer 2 is coated on the surface of the nickel-based superalloy substrate 1.

[0049] Another embodiment of the present invention provides a method for preparing a coating for thermal protection of a nickel-based high-temperature alloy, comprising the following steps:

[0050] S1. Pretreating the nickel-based high-temperature alloy substrate;

[0051] Furthermore, the pretreatment includes: first cleaning the nickel-based high-temperature alloy substrate with an alkaline solution, then ultrasonically cleaning it with deionized water, and after drying, roughening the surface of the substrate.

[0052] Furthermore, the alkali solution is 40-60 g / L KOH;

[0053] After roughening treatment, the roughness of the substrate surface is 3μm≤Ra≤7μm.

[0054] Specifically, the nickel-based high-temperature alloy substrate is cleaned with alkaline solution 2 to 3 times to remove oil stains on the surface of the substrate, and then ultrasonically cleaned with deionized water. After drying, the substrate surface is roughened with corundum sand with a particle size of -15 mesh to +40 mesh to improve the surface roughness, so that the surface roughness of the treated substrate meets the following requirements: 3μm≤Ra≤7μm.

[0055] S2, preparing a NiCoGrAlYSi bonding layer on the surface of the pretreated nickel-based high-temperature alloy substrate by using a supersonic flame spraying method;

[0056] The thickness of the adhesive layer is 0.1 to 0.3 mm, preferably 0.1 to 0.2 mm.

[0057] Furthermore, the conditions of the supersonic flame spraying method are: current 1700-1900A, main gas flow rate 10-20SCFH, powder feeding rate 3.0-5.0g / min. As a preference, the conditions are: current 1700A, main gas flow rate 20SCFH, powder feeding rate 3.0g / min.

[0058] S3, using atmospheric plasma spraying method to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer;

[0059] The thickness of the transition layer is 0.15 to 0.3 mm, preferably 0.2 mm.

[0060] Furthermore, the bonding layer is preheated by a plasma flame method at a temperature of 100 to 200° C., preferably 150° C.; and then the bonding layer is prepared by an atmospheric plasma spraying method (Gd 0.2 Yb 0.2 Y 0.6) 2Zr2O7 transition layer; its preparation conditions are: spraying current 700 - 900 A, main gas Ar flow rate 90 - 120 SCFH, auxiliary gas H2 flow rate 10 - 25 SCFH, powder feeding rate 10 - 40 g / min. Preferably, its preparation conditions are: current 800 A, main gas flow rate 90 SCFH, auxiliary gas H2 flow rate 25 SCFH, powder feeding rate 20 g / min.

[0061] Further, before preparing the (Gd 0.2 Yb 0.2 Y 0.6 ) 2Zr2O7 transition layer by atmospheric plasma spraying on the said bonding layer, first screen and dry the (Gd 0.2 Yb 0.2 Y 0.6 ) 2Zr2O7 agglomerated powder, the mesh number of the screening is -170 mesh to +500 mesh; the drying temperature is 120 °C and the time is 2 - 8 h.

[0062] S4. Prepare the (Gd 0.2 Yb 0.2 Y 0.6 ) 2(Zr 1-x Ce x ) 2O7 (0 < x ≤ 0.4) ceramic layer by atmospheric plasma spraying on the said transition layer.

[0063] The thickness of the ceramic layer is 0.2 - 0.5 mm; preferably 0.3 mm.

[0064] Further, prepare the (Gd 0.2 Yb 0.2 Y 0.6 ) 2(Zr 1-x Ce x ) 2O7 (0 < x ≤ 0.4) ceramic layer by atmospheric plasma spraying, its preparation conditions are: spraying current 800 - 950 A, main gas Ar flow rate 100 - 120 SCFH, auxiliary gas H2 flow rate 10 - 25 SCFH, powder feeding rate 10 - 20 g / min. Preferably, its preparation conditions are: current 900 A, main gas flow rate 110 SCFH, auxiliary gas H2 flow rate 25 SCFH, powder feeding rate 15 g / min. <°

[0065] Further, before preparing the (Gd 0.2 Yb 0.2 Y 0.6 ) 2(Zr 1-x Ce x ) 2O7 (0 < x ≤ 0.4) ceramic layer by atmospheric plasma spraying on the said transition layer, first screen and dry the (Gd 0.2 Yb 0.2 Y0.6 )2(Zr 1-x Ce x )2O7(0 < x ≤ 0.4) agglomerated powder is sieved and dried. The mesh number of the sieving is -200 mesh to +500 mesh; the drying temperature is 120 °C and the time is 2 - 8 h.

[0066] The present invention will be further described below in conjunction with specific embodiments, but it should not be construed as a limitation on the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the above content of the present invention still fall within the protection scope of the present invention.

[0067] Example 1

[0068] A preparation method of a coating for thermal protection of nickel-based superalloys, which comprises the following steps:

[0069] (1) The nickel-based superalloy is cleaned twice with an alkali solution with a concentration of 60 g / L, then ultrasonically cleaned with deionized water for 3 min, and dried at 100 °C for 30 min to remove the moisture on the surface of the nickel-based superalloy substrate. The surface of the nickel-based superalloy substrate is roughened with white corundum sand with a particle size of -30 mesh to +40 mesh to increase the surface roughness to 3 μm ≤ Ra ≤ 7 μm;

[0070] (2) Use a vibrating screen to sieve the (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 agglomerated powder and the (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.9 Ce 0.1 )2O7 agglomerated powder. The sieving mesh numbers are -170 mesh to +300 mesh and -200 to +500 mesh respectively. Use a blast drying oven to dry the sieved powder. The powder drying temperature is 120 °C and the drying time is 2 hours;

[0071] (3) Using NiCoGrAlYSi agglomerated powder as raw material, a bonding layer with a thickness of 0.1 mm is prepared by supersonic flame. The preparation conditions are a current of 1700 A, a main gas flow rate of 10 SCFH, and a powder feeding rate of 3.0 g / min;

[0072] (4) First, use a plasma flame to preheat the bonding layer obtained in step (3), and the treatment temperature is 100 °C. Then, an atmospheric plasma spraying is used to prepare a (Gd 0.2 Yb 0.2 Y 0.6) 2Zr2O7 transition layer, the preparation conditions are spraying current 800A, main gas Ar flow rate 90SCFH, auxiliary gas H2 flow rate 25SCFH, powder feeding rate 20g / min;

[0073] (5) Atmospheric plasma spraying was used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.9 Ce 0.1 )2O7 ceramic layer, the preparation conditions are spraying current 900A, main gas Ar flow rate 110SCFH, auxiliary gas H2 flow rate 25SCFH, powder feeding rate 15g / min. The final product is a NiCoGrAlYSi bonding layer with a thickness of 0.1mm, a (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer and 0.2mm thick (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.9 Ce 0.1 )2O7 ceramic layer composed of thermal protection coating.

[0074] Example 2

[0075] A method for preparing a coating for thermal protection of a nickel-based high-temperature alloy comprises the following steps:

[0076] (1) The nickel-based superalloy was cleaned three times with 40g / L alkali solution, then ultrasonically cleaned with deionized water for 3 minutes and dried at 100°C for 30 minutes to remove moisture from the surface of the nickel-based superalloy substrate. The surface of the nickel-based superalloy substrate was roughened with white corundum sand with a particle size of -30 mesh to +40 mesh to improve the surface roughness to 3μm≤Ra≤5μm;

[0077] (2) Use vibrating screen to (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 aggregate powder and (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.8 Ce 0.2 The 2O7 agglomerate powder was sieved to a mesh size of -200 to +400 and -200 to +400, respectively. The sieved powder was dried in a blast drying oven at a temperature of 120°C for 3 hours.

[0078] (3) Using NiCoGrAlYSi agglomerated powder as raw material, a bonding layer with a thickness of 0.1 mm was prepared by supersonic flame. The preparation conditions were current 1700 A, main gas flow rate 20 SCFH, and powder feeding rate 3.0 g / min;

[0079] (4) First, the bonding layer obtained in step (3) was preheated by plasma flame at a temperature of 150°C. Then, atmospheric plasma spraying was used to prepare a 0.3 mm thick (Gd 0.2 Yb 0.2 Y 0.6 ) 2Zr2O7 transition layer, the preparation conditions are spraying current 700A, main gas Ar flow rate 120SCFH, auxiliary gas H2 flow rate 25SCFH, powder feeding rate 20g / min;

[0080] (5) Atmospheric plasma spraying was used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.8 Ce 0.2 )2O7 ceramic layer, the preparation conditions are spraying current 800A, main gas Ar flow rate 100SCFH, auxiliary gas H2 flow rate 10SCFH, powder feeding rate 10g / min. The final product is a NiCoGrAlYSi bonding layer with a thickness of 0.1mm, a (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer, 0.3mm thick (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.8 Ce 0.2 )2O7 ceramic layer composed of thermal protection coating.

[0081] Example 3

[0082] A method for preparing a coating for thermal protection of a nickel-based high-temperature alloy comprises the following steps:

[0083] (1) The nickel-based superalloy was cleaned twice with 60g / L alkali solution, then ultrasonically cleaned with deionized water for 3 minutes, and dried at 100°C for 30 minutes to remove moisture from the surface of the nickel-based superalloy substrate. The surface of the nickel-based superalloy substrate was roughened with white corundum sand with a particle size of -30 mesh to +40 mesh to increase the surface roughness to 3μm≤Ra≤7μm;

[0084] (2) Use vibrating screen to (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 aggregate powder and (Gd0.2 Yb 0.2 Y 0.6 )2(Zr 0.7 Ce 0.3 The 2O7 agglomerate powder was sieved to a mesh size of -300 to +400 and -300 to +400, respectively. The sieved powder was dried in a blast drying oven at a temperature of 120°C for 2 hours.

[0085] (3) Using NiCoGrAlYSi agglomerated powder as raw material, a bonding layer with a thickness of 0.2 mm was prepared by supersonic flame. The preparation conditions were current 1700 A, main gas flow rate 20 SCFH, and powder feeding rate 3.0 g / min;

[0086] (4) First, the bonding layer obtained in step (3) was preheated by plasma flame at a temperature of 200°C. Then, atmospheric plasma spraying was used to prepare a 0.2 mm thick (Gd 0.2 Yb 0.2 Y 0.6 ) 2Zr2O7 transition layer, the preparation conditions are spraying current 800A, main gas Ar flow rate 100SCFH, auxiliary gas H2 flow rate 20SCFH, powder feeding rate 20g / min;

[0087] (5) Atmospheric plasma spraying was used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.8 Ce 0.2 )2O7 ceramic layer, the preparation conditions are spraying current 850A, main gas Ar flow rate 120SCFH, auxiliary gas H2 flow rate 15SCFH, powder feeding rate 15g / min. The final result is a NiCoGrAlYSi bonding layer with a thickness of 0.2mm, a (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer and 0.3mm thick (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 0.7 Ce 0.3 )2O7 ceramic layer composed of thermal protection coating.

[0088] The thermal protective coatings prepared in Examples 1 to 3 were tested respectively:

[0089] The above examples 1 to 3 prepared the NiCoGrAlYSi bonding layer, (Gd 0.2 Yb 0.2 Y 0.6)2Zr2O7 transition layer and (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7(0 < x ≤ 0.4) ceramic layer, and its structure, morphology and composition were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

[0090] (1) Observation of the appearance morphology of the thermal protection coating specimen:

[0091] Figure 2 The appearance morphology of the thermal protection coating specimen prepared in Example 1 of the present invention is shown.

[0092] (2) Observation of the microstructure morphology of the thermal protection coating specimen:

[0093] The microstructure morphology of the prepared coating cross-section was observed using a cold field emission scanning electron microscope S-4800 type of Japan High-Tech Co., Ltd. Figure 3 The cross-section microstructure morphology of the thermal protection coating prepared in Example 1 of the present invention is shown.

[0094] (3) Testing of the heat insulation effect of the thermal protection coating specimen:

[0095] A self-made device was used to test the heat insulation effect of the thermal protection coating. An oxyacetylene flame was used as the heat source. The test conditions were: controlling the surface temperature at 1400 ± 20 °C and continuously heating for 12,000 S. This device mainly consisted of an ablation gun, a protective ring, gaskets, an optical pyrometer, thermocouples, a workbench, etc. The specific experimental steps were: a. Ignite the oxyacetylene flame and adjust the oxygen and acetylene gas flow rates and the distance from the flame nozzle to the specimen surface to make the specimen surface temperature stable at 1400 ± 20 °C; b. Record the hot surface temperature and cold surface temperature of the specimen on the record sheet every 15 seconds; c. After the ablation time reached 12,000 s, remove the oxyacetylene flame to stop ablation, and at the same time close the oxygen and acetylene gas valves. Figure 4 The heat insulation effect diagram of the thermal protection coating prepared in Example 3 of the present invention is shown, where Curve 1 is the hot surface temperature and Curve 2 is the temperature on the back of the substrate.

[0096] From Figure 4 it can be seen that the heat insulation effect of the thermal protection coating prepared by the present invention is relatively high. When controlling the hot surface temperature at 1400 °C, the thermal protection coating can achieve a temperature drop of nearly 300 °C, and the thermal protection of nickel-based superalloys can be achieved.

[0097] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed in a certain embodiment, the relevant descriptions of other embodiments can be referred to.

[0098] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A coating for thermal protection of nickel-based high-temperature alloys, characterized by: The coating consists of a bonding layer, a transition layer and a ceramic layer stacked in sequence; wherein, The bonding layer is NiCoCrAlYSi with a thickness of 0.2-0.3 mm; the bonding layer is prepared by supersonic flame spraying with a powder feeding rate of 3.0-5.0 g / min; The transition layer is (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7, the thickness of which is 0.15~0.3 mm; The ceramic layer is (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7, where 0 < x ≤ 0.4 and its thickness is 0.3 mm.

2. A method for preparing a coating for thermal protection of nickel-based high-temperature alloys, characterized in that: include: Pretreating the nickel-based high-temperature alloy substrate; A NiCoCrAlYSi bonding layer is prepared on the surface of a pretreated nickel-based high-temperature alloy substrate by a supersonic flame spraying method, with a powder feeding rate of 3.0-5.0 g / min; the thickness of the bonding layer is 0.2-0.3 mm; The atmospheric plasma spraying method is used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer, the thickness of which is 0.15~0.3 mm; Prepare a (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 ceramic layer on the transition layer by atmospheric plasma spraying, where 0 < x ≤ 0.4 and its thickness is 0.3 mm.

3. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 2, characterized in that: The pretreatment includes: first cleaning the nickel-based high-temperature alloy substrate with alkaline solution, then ultrasonically cleaning it with deionized water, drying it, and then roughening the surface of the substrate.

4. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 3, characterized in that: The alkali solution is 40-60 g / L KOH; After roughening treatment, the roughness of the substrate surface is 3μm≤Ra≤7μm.

5. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 2, characterized in that: The conditions of the supersonic flame spraying method are: current 1700-1900 A, main gas flow rate 10-20 SCFH.

6. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 2, characterized in that: The atmospheric plasma spraying method is used to prepare (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer, comprising: First, the bonding layer is preheated by a plasma flame method at a temperature of 100-200°C; then, the bonding layer is prepared by an atmospheric plasma spraying method (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer; its preparation conditions are: spraying current 700~900 A, main gas Ar flow rate 90~120 SCFH, auxiliary gas H2 flow rate 10~25 SCFH, powder feeding rate 10~40 g / min.

7. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 2 or 6, characterized in that: In the process of preparing (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 transition layer, first (Gd 0.2 Yb 0.2 Y 0.6 )2Zr2O7 agglomerate powder is sieved and dried, the sieving mesh size is -170 mesh to +500 mesh; the drying temperature is 120°C and the time is 2 to 8 hours.

8. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 2, characterized in that: Prepare (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 ceramic layer, where 0 < x ≤ 0.4, and its preparation conditions are: spraying current 800 - 950 A, main gas Ar flow rate 100 - 120 SCFH, auxiliary gas H2 flow rate 10 - 25 SCFH, powder feeding rate 10 - 20 g / min.

9. The method for preparing a coating for thermal protection of nickel-based high-temperature alloys according to claim 2 or 8, characterized in that: In the process of preparing (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 ceramic layer, first (Gd 0.2 Yb 0.2 Y 0.6 )2(Zr 1-x Ce x )2O7 agglomerate powder is sieved and dried, the sieving mesh size is -200 mesh to +500 mesh; the drying temperature is 120°C and the time is 2 to 8 hours.

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