Preparation method of thermal barrier coating

Abstract

The invention provides a preparation method of a thermal barrier coating, and relates to the technical field of thermal barrier coatings. The preparation method comprises the following steps: preparation of a bonding layer: preparing a single beta-phase NiAl-based bonding layer on the surface of a matrix; preheating treatment is conducted, specifically, in the vacuum inert atmosphere, a spray gun is adopted for conducting preheating treatment on the NiAl-based bonding layer; o2 is introduced into the process chamber, and a spray gun is adjusted to perform heating treatment on the NiAl-based bonding layer according to spray deposition parameters; preparing a ceramic layer: feeding powder, and spraying and depositing the ceramic layer on the surface of the NiAl-based bonding layer by adopting a spray gun according to spraying deposition parameters; and cooling treatment is conducted, specifically, the NiAl-based bonding layer and the ceramic layer are cooled to the preset temperature at the preset speed, and the thermal barrier coating is obtained. The thermal barrier coating prepared by the preparation method is relatively good in oxidation resistance and thermal shock resistance.

Description

Technical Field

[0001] The invention relates to the technical field of thermal barrier coatings, and in particular to a method for preparing a thermal barrier coating. Background Art

[0002] PS-PVD (Plasma Spraying-Physical Vapor Deposition) coating is a highly efficient gas-solid-liquid three-phase composite controlled deposition technology. When the gas phase is used as the main deposition, a quasi-columnar structure coating can be obtained. Due to the gas phase nucleation preferential competitive growth mode and the presence of a small amount of liquid phase and condensed nanoclusters, the coating forms a structure with well-developed dendrites, so that the coating has high porosity and low thermal conductivity. At the same time, the quasi-columnar structure coating has high strain tolerance and long life.

[0003] In thermal barrier coatings, the TGO layer (Thermally Grown Oxide) at the interface between the bonding layer and the ceramic layer is one of the key factors that determine the life of the coating. In the prior art, during the preparation of the ceramic layer using the PS-PVD process, a certain flow of oxygen is generally introduced to prevent the thermal barrier coating of the oxide ceramic from being deoxidized during the gasification and evaporation of the high-energy plasma beam, resulting in the mutual diffusion of the bonding layer and the metal elements and the rapid failure of the thermal barrier coating system. Accordingly, the oxygen introduced is more used to neutralize and supplement the deoxidation of the oxide ceramic, resulting in insufficient growth of the interface pre-oxidation film. Even if oxygen is continuously introduced during the subsequent spray deposition process, the density and continuity of the TGO layer are poor, resulting in poor oxidation resistance and thermal shock life of the thermal barrier coating. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a thermal barrier coating to solve the technical problems in the prior art that the density and continuity of the TGO layer in the thermal barrier coating are poor, and the oxidation resistance and thermal shock life of the thermal barrier coating are also poor.

[0005] In order to solve the above problems, the present invention provides a method for preparing a thermal barrier coating, comprising the following steps:

[0006] Preparation of bonding layer: a single β-phase NiAl-based bonding layer is prepared on the surface of the substrate;

[0007] Preheating treatment: the substrate is mounted in a process chamber of a PS-PVD device, and the NiAl-based bonding layer is preheated by using a spray gun in a vacuum inert atmosphere;

[0008] Pre-oxidation treatment: introducing O2 into the process chamber, adjusting the spray gun to heat the NiAl-based bonding layer according to the spray deposition parameters;

[0009] Preparation of ceramic layer: Keep O2 flowing into the process chamber, feed powder, and use the spray gun to spray and deposit the ceramic layer on the surface of the NiAl-based bonding layer with the spray deposition parameters; wherein a TGO layer of α-alumina is formed between the ceramic layer and the NiAl-based bonding layer;

[0010] Cooling treatment: The NiAl-based bonding layer and the ceramic layer are subjected to cooling treatment to reduce the temperature to a preset temperature at a preset speed to obtain a thermal barrier coating.

[0011] Optionally, in the preheating treatment step, the substrate is clamped on a turntable in the process chamber, and the process chamber is adjusted to an inert atmosphere and a vacuum degree of 200 Pa; the rotation speed of the turntable is adjusted to 60-80 rpm, and the manipulator drives the spray gun to swing up and down 30-50 mm, the swing rate is 90-110 mm / s, and the spraying distance is 1-1.4 m; the spray gun is adjusted to preheat the NiAl-based bonding layer with an input power of 15-25 kW, 35-45 kW and 55-65 kW in sequence, wherein each power level is preheated for 1.5-2.5 min.

[0012] Optionally, in the pre-oxidation step, Ar, He and O2 are introduced into the process chamber, wherein the flow rate of Ar is 25-35slpm, and the flow rate of He is 55-65slpm, and both are used as spray gun plasma gas input; the flow rate of O2 is 2-4slpm, and is input from the top of the process chamber; the spray deposition current of the spray gun is adjusted to 1800-2200A, and the NiAl-based bonding layer is heat treated for 10-20s.

[0013] Optionally, in the cooling treatment step, after spraying and depositing the ceramic layer, the spray gun is adjusted to cool the NiAl-based bonding layer and the ceramic layer with input powers of 55-65kW, 35-45kW and 15-25kW in sequence, wherein each power level is cooled for 1.5-2.5 minutes until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining the thermal barrier coating.

[0014] Optionally, the step of preparing the bonding layer includes:

[0015] A single β-phase NiAl-based bonding layer is prepared on the surface of the substrate by using a vapor phase infiltration technique, and a vacuum heat treatment is performed at 950-1000° C. for 3-5 hours;

[0016] Alternatively, a single β-phase NiAl-based bonding layer is prepared on the surface of the substrate using chemical vapor deposition technology.

[0017] Optionally, the NiAl-based bonding layer has a thickness ranging from 40 to 60 μm.

[0018] Optionally, after the bonding layer preparation step, a surface roughening treatment step is also included: at a pressure of 0.2 to 0.3 MPa, the NiAl-based bonding layer is wet-sandblasted using 100 to 200 mesh white jade steel to make the surface roughness 0.9 to 1.3 μm, and the sum of the mass ratios of Ni and Al in the NiAl-based bonding layer is greater than 96%.

[0019] Optionally, the ceramic layer is an 8YSZ coating.

[0020] Optionally, in the step of preparing the ceramic layer, a double-sided powder feeding method is adopted, and the powder feeding amount is 2×5 g / min.

[0021] In the preparation method provided by the present invention:

[0022] (1) The prepared NiAl-based bonding layer is a single β phase with a high Al content, and the NiAl-based bonding layer is preheated in a vacuum inert atmosphere to reduce the consumption of Al under low temperature conditions, thereby ensuring the effective reaction amount of Al in the subsequent pre-oxidation treatment step and the ceramic layer preparation step, and correspondingly ensuring the density and continuity of the generated α-alumina TGO layer, and the α-alumina TGO layer has a low growth rate under long-term cycle conditions, thereby improving the oxidation resistance and thermal shock life of the thermal expansion coating.

[0023] (2) A pre-oxidation treatment step is provided, so that the high content Al in the NiAl-based bonding layer can fully contact and react with O2 under high temperature conditions, thereby ensuring the density and continuity of the generated α-alumina TGO layer; in the ceramic layer preparation step, on the basis of achieving the preparation of the ceramic layer, part of the O2 can further react with the Al in the NiAl-based bonding layer to generate α-alumina, thereby further improving the density and continuity of the α-alumina TGO layer, and correspondingly further improving the oxidation resistance and thermal shock life of the thermal barrier coating.

[0024] (3) The high-temperature NiAl-based bonding layer, α-alumina TGO layer and ceramic layer are slowly cooled to form a thermal barrier coating with low internal stress, thereby further improving the thermal shock life of the thermal barrier coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1This is a cross-sectional morphology diagram of a thermal barrier coating prepared according to Example 1 of the present invention;

[0027] Figure 2 This is a cross-sectional morphology diagram of the thermal barrier coating prepared according to Example 1 of the present invention after 60 thermal shocks;

[0028] Figure 3 (a) is a cross-sectional morphology of the thermal barrier coating prepared according to Example 1 of the present invention after being thermally cycled at 1100° C. for 350 h;

[0029] Figure 3 (b) is a cross-sectional morphology of the thermal barrier coating prepared according to the comparative example after being thermally cycled at 1100°C for 350 hours;

[0030] Figure 4 This is a cross-sectional morphology diagram of a thermal barrier coating prepared according to Example 2 of the present invention;

[0031] Figure 5 This is a cross-sectional morphology diagram of the thermal barrier coating prepared according to Example 2 of the present invention after 60 thermal shocks;

[0032] Figure 6 This is a cross-sectional morphology diagram of the thermal barrier coating prepared according to Example 3 of the present invention after 60 thermal shocks;

[0033] Figure 7 for Figure 6 Fluorescence spectrum analysis and fitting peak results of the cross section of the thermal barrier coating;

[0034] Figure 8 The cross-sectional fluorescence spectrum analysis and fitting peak separation results of the thermal barrier coating prepared according to Example 4 of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] This embodiment provides a method for preparing a thermal barrier coating, including a bonding layer preparation step, a preheating treatment step, a preoxidation treatment step, a ceramic layer preparation step, and a cooling treatment step, which are specifically as follows:

[0039] Preparation of bonding layer: A single β-phase NiAl-based bonding layer is prepared on the substrate surface. In the case of a single β-phase, the ratio of Ni and Al in the NiAl-based bonding layer is 1:1, the Al content is high, and the oxidation resistance is better; the NiAl-based bonding layer also contains a small amount of Cr, Y, Si and other elements.

[0040] Preheating treatment: The substrate is loaded into the process chamber of the PS-PVD equipment, and the NiAl-based bonding layer is preheated using a spray gun in a vacuum inert atmosphere. The process chamber is in a vacuum inert atmosphere, in which the inert gas also serves as the plasma gas of the spray gun; the preheating treatment can effectively reduce the reaction consumption of Al in the NiAl-based bonding layer with O2 at low temperature, ensuring the subsequent pre-oxidation treatment.

[0041] Pre-oxidation treatment: Plasma gas and O2 are introduced into the process chamber, and the spray gun is adjusted to heat the NiAl-based bonding layer with spray deposition parameters. The spray gun keeps heating the NiAl-based bonding layer, and the plasma gas, heating power, and current are different from the preheating treatment step; accordingly, the temperature of the NiAl-based bonding layer continues to rise, and Al reacts with O2 at high temperature to generate a TGO layer of α-alumina with high stability and excellent heat resistance, and the outer surface of the NiAl-based bonding layer can fully contact and react with O2, thereby ensuring the continuity, integrity, and density of the generated α-alumina TGO layer.

[0042] Preparation of ceramic layer: plasma gas and O2 are kept flowing into the process chamber, powder is fed, and a spray gun is used to spray and deposit a ceramic layer on the surface of the NiAl-based bonding layer with spray deposition parameters; wherein a TGO layer of α-alumina is formed between the ceramic layer and the NiAl-based bonding layer. The powder material melts in the spray gun jet and is deposited on the outer surface of the NiAl-based bonding layer to form a ceramic layer, wherein during the deposition process, part of the O2 is used to neutralize and supplement the deoxidation of the oxide ceramic, and the other part of the O2 can continue to react with Al in the NiAl-based bonding layer to generate α-alumina, thereby further improving the density and continuity of the TGO layer of α-alumina.

[0043] Cooling treatment: The NiAl-based bonding layer and the ceramic layer are cooled to a preset temperature at a preset speed to obtain a thermal barrier coating. After the ceramic layer is prepared, the temperature of the NiAl-based bonding layer and the ceramic layer is relatively high, and the heating power of the spray gun to the NiAl-based bonding layer and the ceramic layer is gradually reduced, and the temperature of the NiAl-based bonding layer and the ceramic layer is slowly cooled, so as to achieve slow cooling of the NiAl-based bonding layer and the ceramic layer, so as to reduce the occurrence of excessive internal stress of the substrate and the coating caused by rapid cooling of the NiAl-based bonding layer and the ceramic layer; after the cooling treatment is completed, a thermal barrier coating with less stress is obtained on the outer wall of the substrate.

[0044] Then in the preparation method of the present application:

[0045] (1) The prepared NiAl-based bonding layer is a single β phase with a high Al content, and the NiAl-based bonding layer is preheated in a vacuum inert atmosphere to reduce the consumption of Al under low temperature conditions, thereby ensuring the effective reaction amount of Al in the subsequent pre-oxidation treatment step and the ceramic layer preparation step, and correspondingly ensuring the density and continuity of the generated α-alumina TGO layer, and the α-alumina TGO layer has a low growth rate under long-term cycle conditions, thereby improving the oxidation resistance and thermal shock life of the thermal expansion coating.

[0046] (2) A pre-oxidation treatment step is provided, so that the high content Al in the NiAl-based bonding layer can fully contact and react with O2 under high temperature conditions, thereby ensuring the density and continuity of the generated α-alumina TGO layer; in the ceramic layer preparation step, on the basis of achieving the preparation of the ceramic layer, part of the O2 can further react with the Al in the NiAl-based bonding layer to generate α-alumina, thereby further improving the density and continuity of the α-alumina TGO layer, and correspondingly further improving the oxidation resistance and thermal shock life of the thermal barrier coating.

[0047] (3) The high-temperature NiAl-based bonding layer, α-alumina TGO layer and ceramic layer are slowly cooled to form a thermal barrier coating with low internal stress, thereby further improving the thermal shock life of the thermal barrier coating.

[0048] Specifically, in the present embodiment, in the step of preparing the bonding layer, a single β-phase NiAl-based bonding layer can be prepared on the surface of the substrate by using vapor infiltration technology or chemical vapor deposition technology, wherein after the single β-phase NiAl-based bonding layer is prepared on the surface of the substrate by using vapor infiltration technology, the NiAl-based bonding layer can be heat-treated for 3 to 5 hours under vacuum conditions at 950 to 1000°C to reduce the internal stress; or, a single β-phase NiAl-based bonding layer can be prepared on the surface of the substrate by using chemical vapor deposition technology, and a NiAl-based bonding layer with lower internal stress can be obtained without additional heat treatment.

[0049] Specifically, the thickness of the NiAl-based bonding layer may range from 40 to 60 μm to ensure the oxidation resistance and thermal shock life of the thermal barrier coating.

[0050] In the preparation method provided in this embodiment, after the NiAl-based bonding layer is prepared, its surface can also be roughened: at a pressure of 0.2 to 0.3 MPa, the NiAl-based bonding layer is wet-sandblasted with 100 to 200 mesh white jade steel to make the surface roughness 0.9 to 1.3 μm, and the sum of the mass ratios of Ni and Al in the NiAl-based bonding layer is greater than 96%. The NiAl-based bonding layer is wet-sandblasted with white jade steel to enhance the surface adhesion of the NiAl-based bonding layer, and correspondingly increase the adhesion strength of the generated α-alumina TGO layer, the ceramic layer and the NiAl-based bonding layer, thereby further improving the thermal shock performance of the thermal barrier coating. Among them, after wet-sandblasting, the sum of the mass ratios of Ni and Al is ensured to be greater than 96% to ensure that the NiAl-based bonding layer is a single β phase; specifically, a handheld XRF can be used to measure the composition of each metal element in the NiAl-based bonding layer.

[0051] Optionally, in this embodiment, the specific operation of the preheating treatment step is as follows: mount the substrate on a turntable in the process chamber, adjust the process chamber to an inert atmosphere and a vacuum degree of 200Pa; adjust the rotation speed of the turntable to 60-80rpm, and the manipulator drives the spray gun to swing up and down 30-50mm, the swing rate is 90-110mm / s, and the spraying distance is 1-1.4m; adjust the spray gun to preheat the NiAl-based bonding layer with an input power of 15-25kW, 35-45kW and 55-65kW in sequence, wherein each power level is preheated for 1.5-2.5min. Among them, the process chamber can be first evacuated to 200Pa, and then Ar is introduced into the process chamber, and then the process chamber is evacuated to 200Pa again, and the process chamber is adjusted to maintain this state during the process; wherein, a step-by-step equal-time preheating method is adopted to improve the preheating uniformity of the NiAl-based bonding layer, prepare for the subsequent pre-oxidation treatment step, and ensure the uniformity of the reaction of each area of ​​the NiAl-based bonding layer with O2 in the pre-oxidation treatment step, thereby ensuring the uniformity and continuity of the generated α-alumina TGO layer.

[0052] Wherein, after the preheating step, the temperature of the NiAl-based bonding layer is above 700°C.

[0053] In this embodiment, in the pre-oxidation step, Ar, He and O2 are introduced into the process chamber, wherein the flow rate of Ar is 25-35slpm, and the flow rate of He is 55-65slpm, and both are used as plasma gas input for the spray gun; the flow rate of O2 is 2-4slpm, and is input from the top of the process chamber; the spray deposition current of the spray gun is adjusted to 1800-2200A, and the NiAl-based bonding layer is heated for 10-20s. After the preheating step is completed, the spray gun continues to heat the NiAl-based bonding layer so that the Al in the NiAl-based bonding layer can fully contact and react with O2 under high temperature conditions to generate α-alumina, thereby forming a continuous and dense α-alumina TGO layer on the surface of the NiAl-based bonding layer.

[0054] Optionally, in the present embodiment, in the step of preparing the ceramic layer, a double-sided powder feeding method is adopted, and the powder feeding amount is 2×5g / min. After the pre-oxidation treatment step is completed, Ar, He and O2 are continuously input into the process chamber, and the input flow rate of each gas remains unchanged, the current and power of the spray gun are adjusted, and a double-sided powder feeding method is adopted to prepare a ceramic layer on the outer wall of the NiAl-based bonding layer; after the ceramic layer preparation step is completed, from the inside to the outside, there are a substrate, a NiAl-based bonding layer coated on the surface of the substrate, an α-alumina TGO layer coated on the surface of the NiAl-based bonding layer, and a ceramic layer coated on the surface of the α-alumina TGO layer, and the inner layer of the α-alumina TGO layer here is formed in the pre-oxidation treatment step, and the outer layer is formed in the ceramic layer preparation step; specifically, the ceramic layer is an 8YSZ coating.

[0055] In this embodiment, in the cooling treatment step, after spraying and depositing the ceramic layer, the spray gun is adjusted to cool the NiAl-based bonding layer and the ceramic layer with an input power of 55-65kW, 35-45kW and 15-25kW in sequence, wherein each power level is cooled for 1.5-2.5min until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining a thermal barrier coating. A step-by-step equal-time cooling method is adopted to ensure that the temperature of the NiAl-based bonding layer and the ceramic layer slowly decreases to below 500°C, thereby completing the preparation of the thermal barrier coating, and effectively reducing the internal stress of the substrate and the thermal barrier coating, thereby further improving the thermal shock life of the thermal barrier coating; then, after Ar is filled into the process chamber for a certain period of time, air is continuously filled into the process chamber to make the process chamber reach atmospheric pressure, and then the process chamber is opened to take out the product.

[0056] Preferably, the preparation method of the thermal barrier coating provided in this embodiment can be applied to the preparation of guide blades of a turbine in an aircraft engine or a gas turbine, the guide blade comprising a blade body and a thermal barrier coating coated on the blade body, wherein the blade body serves as a substrate and the thermal barrier coating is prepared using the above-mentioned preparation method.

[0057] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0058] Embodiment 1:

[0059] Step 1: Preparation of bonding layer: A single β-phase NiAl-based bonding layer with an average thickness of 40.5 μm is deposited on the surface of the single-crystal turbine guide blade using a vapor phase infiltration technique, and then vacuum heat-treated at 980°C for 4 hours.

[0060] Step 2: Surface roughening treatment: Under a pressure of 0.2MPa, wet sandblast the NiAl-based bonding layer with 100-mesh white corundum. After sandblasting the blade spraying area back and forth for 1 time, there is no oxidation color on the surface; the mass ratio of Ni and Al on the surface of the NiAl-based bonding layer is measured by handheld XRF, which is always 97%; the surface roughness Ra of the NiAl-based bonding layer is 1.2μm.

[0061] Step 3: Preheating:

[0062] ① Install the guide blade on the turntable in the process chamber of the PS-PVD equipment, adjust the process chamber to an inert atmosphere and a vacuum degree of 200Pa; adjust the speed of the turntable to 70rpm, and the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m.

[0063] ② Adjust the spray gun to preheat the NiAl-based bonding layer with input powers of 20 kW, 40 kW and 60 kW in sequence, with each power level preheating for 2 minutes.

[0064] Step 4: Pre-oxidation treatment: keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; introduce Ar30slpm, He60slpm and O22slpm into the process chamber, adjust the spray deposition current of the spray gun to 2000A, and ventilate for 10s.

[0065] Step 5: Preparation of ceramic layer: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; at the same time, continue to introduce Ar30slpm, He60slpm and O22 slpm into the process chamber, and the spray deposition current of the spray gun is maintained at 2000A; adopt a double-sided powder feeding method, and the powder feeding amount is 2×5g / min, and run according to the above parameters until the specified spraying time.

[0066] Step 6: Cooling treatment: adjust the spray gun to cool the NiAl-based bonding layer and the ceramic layer with input powers of 60kW, 40kW and 20kW in turn, wherein each power level is cooled for 2 minutes until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining a thermal barrier coating and forming an α-alumina TGO layer between the ceramic layer and the NiAl-based bonding layer; inflate, open the process chamber and take out the guide vanes.

[0067] Figure 1 This is a cross-sectional morphology diagram of a thermal barrier coating prepared according to Example 1 of the present invention. Figure 1 As shown, a dense and continuous α-alumina TGO layer (pre-oxidation film) is formed at the interface between the NiAl-based bonding layer and the ceramic layer.

[0068] Figure 2 The cross-sectional morphology of the thermal barrier coating prepared according to Example 1 of the present invention after 60 thermal shocks. Specifically, the guide vane with the thermal barrier coating prepared in Example 1 was placed in a muffle furnace and heated to 1100°C, kept warm for 5 to 10 minutes, and water quenched in pure water at 20±5°C. After 60 reciprocating cycles, the thermal barrier coating did not peel off. Figure 2 It can be seen that under the high temperature and water-containing quenching environment, the growth rate of the TGO layer is low, and it still maintains the characteristics of a dense thin layer. No obvious spinel phase characteristics appear in the backscattering mode, and only slight cracking occurs inside the TGO layer.

[0069] Figure 3 (a) is a cross-sectional morphology of the thermal barrier coating prepared according to Example 1 of the present invention after being subjected to a 1100°C thermal cycle for 350 hours. Figure 3 (a) It can be seen that the growth rate of the α-alumina TGO layer during the thermal cycle high-temperature oxidation process is low, but it still remains dense and continuous.

[0070] Embodiment 2:

[0071] Step 1: Preparation of bonding layer: A single β-phase NiAl-based bonding layer with an average thickness of 59.6 μm is deposited on the surface of the single-crystal turbine guide blade using chemical vapor deposition technology.

[0072] Step 2: Surface roughening treatment: Under a pressure of 0.2MPa, wet sandblast the NiAl-based bonding layer with 150 mesh white corundum. After sandblasting the blade spraying area 2 times back and forth, there is no oxidation color on the surface; the mass ratio of Ni and Al on the surface of the NiAl-based bonding layer is measured by handheld XRF, which is 96.7%; the surface roughness Ra of the NiAl-based bonding layer is 0.9μm.

[0073] Step 3: Preheating:

[0074] ① Install the guide blade on the turntable in the process chamber of the PS-PVD equipment, adjust the process chamber to an inert atmosphere and a vacuum degree of 200Pa; adjust the speed of the turntable to 70rpm, and the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m.

[0075] ② Adjust the spray gun to preheat the NiAl-based bonding layer with input powers of 20 kW, 40 kW and 60 kW in sequence, with each power level preheating for 2 minutes.

[0076] Step 4: Pre-oxidation treatment: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; introduce Ar30slpm, He60slpm and O22 slpm into the process chamber, adjust the spray deposition current of the spray gun to 2000A, and ventilate for 20s.

[0077] Step 5: Preparation of ceramic layer: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; at the same time, continue to introduce Ar30slpm, He60slpm and O22 slpm into the process chamber, and the spray deposition current of the spray gun is maintained at 2000A; adopt a double-sided powder feeding method, and the powder feeding amount is 2×5g / min, and run according to the above parameters until the specified spraying time.

[0078] Step 6: Cooling treatment: adjust the spray gun to cool the NiAl-based bonding layer and the ceramic layer with input powers of 60kW, 40kW and 20kW in turn, wherein each power level is cooled for 2 minutes until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining a thermal barrier coating and forming an α-alumina TGO layer between the ceramic layer and the NiAl-based bonding layer; inflate, open the process chamber and take out the guide vanes.

[0079] Figure 4 This is a cross-sectional morphology diagram of a thermal barrier coating prepared according to Example 2 of the present invention. Figure 4 As shown, the pre-oxidation film is continuous and dense.

[0080] Figure 5The cross-sectional morphology of the thermal barrier coating prepared according to Example 2 of the present invention after 60 thermal shocks. Specifically, the guide vane with the thermal barrier coating prepared in Example 2 was placed in a muffle furnace and heated to 1100°C, kept warm for 5 to 10 minutes, and water quenched in pure water at 20±5°C. After 60 reciprocating cycles, there was no obvious ceramic layer / bonding layer interface peeling of the thermal barrier coating, and only a small amount of ceramic layer interlayer peeling; Figure 5 It can be seen that under high temperature and water-containing quenching environment, the TGO layer has a low growth rate and still maintains the characteristics of a dense thin layer. No obvious spinel phase characteristics appear in the backscattering mode, and only slight cracking occurs inside the TGO layer. The thickness of the TGO layer is 2 to 5 μm.

[0081] Embodiment 3:

[0082] Step 1: Preparation of bonding layer: A single β-phase NiAl-based bonding layer with an average thickness of 50.7 μm is deposited on the surface of the single-crystal turbine guide blade using a vapor phase infiltration technique, and then vacuum heat-treated at 980°C for 4 hours.

[0083] Step 2: Surface roughening treatment: Under a pressure of 0.3 MPa, wet sandblast the NiAl-based bonding layer with 120 mesh white corundum. After sandblasting the blade spraying area 3 times back and forth, there is no oxidation color on the surface; the mass ratio of Ni and Al on the surface of the NiAl-based bonding layer is measured by handheld XRF, which is 97.1%; the surface roughness Ra of the NiAl-based bonding layer is 1.3 μm.

[0084] Step 3: Preheating:

[0085] ① Install the guide blade on the turntable in the process chamber of the PS-PVD equipment, adjust the process chamber to an inert atmosphere and a vacuum degree of 200Pa; adjust the speed of the turntable to 70rpm, and the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m.

[0086] ② Adjust the spray gun to preheat the NiAl-based bonding layer with input powers of 20 kW, 40 kW and 60 kW in sequence, with each power level preheating for 2 minutes.

[0087] Step 4: Pre-oxidation treatment: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; introduce Ar30slpm, He60slpm and O24 slpm into the process chamber, adjust the spray deposition current of the spray gun to 2000A, and ventilate for 10s.

[0088] Step 5: Preparation of ceramic layer: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; at the same time, continue to introduce Ar30slpm, He60slpm and O24 slpm into the process chamber, and the spray deposition current of the spray gun is maintained at 2000A; adopt a double-sided powder feeding method, and the powder feeding amount is 2×5g / min, and run according to the above parameters until the specified spraying time.

[0089] Step 6: Cooling treatment: adjust the spray gun to cool the NiAl-based bonding layer and the ceramic layer with input powers of 60kW, 40kW and 20kW in turn, wherein each power level is cooled for 2 minutes until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining a thermal barrier coating and forming an α-alumina TGO layer between the ceramic layer and the NiAl-based bonding layer; inflate, open the process chamber and take out the guide vanes.

[0090] Figure 6 The cross-sectional morphology of the thermal barrier coating prepared according to Example 3 of the present invention after 60 thermal shocks. Specifically, the guide vane with thermal barrier coating prepared in Example 3 was placed in a muffle furnace and heated to 1100°C, kept warm for 5 to 10 minutes, and water quenched in pure water at 20±5°C. After 60 reciprocating cycles, there was no obvious ceramic layer / bonding layer interface peeling of the coating, and only a small amount of ceramic layer interlayer peeling; Figure 6 It can be seen that under the high temperature and water-containing quenching environment, the growth rate of the TGO layer is low, and it still maintains the characteristics of a dense thin layer. No obvious spinel phase characteristics appear in the backscattering mode, and only slight cracking occurs inside the TGO layer.

[0091] Figure 7 for Figure 6 Fluorescence spectrum analysis and fitting peak results of the cross section of thermal barrier coating. Figure 7 It can be seen that the four waves are the cross-sectional test wave, fitting wave, sub-wave 1 of the fitting wave, and sub-wave 2 of the fitting wave of the thermal barrier coating prepared in Example 3. The R2 standard peak of α-alumina is located at 14430.4 cm -1 The R2 peak of the α-alumina TGO layer in the thermal barrier coating is at 14428.1 cm -1 , which has a low deviation from the standard peak, indicating that the stress at the cross-sectional interface between the NiAl-based bonding layer and the 8YSZ ceramic layer is small due to the α-alumina TGO layer.

[0092] Embodiment 4:

[0093] Step 1: Preparation of bonding layer: A single β-phase NiAl-based bonding layer with an average thickness of 49.5 μm is deposited on the surface of the single-crystal turbine guide blade using a vapor phase infiltration technique, and then vacuum heat-treated at 980°C for 4 hours.

[0094] Step 2: Surface roughening treatment: Under a pressure of 0.2MPa, wet sandblast the NiAl-based bonding layer with 100-mesh white corundum. After sandblasting the blade spraying area 3 times back and forth, there is no oxidation color on the surface; the mass ratio of Ni and Al on the surface of the NiAl-based bonding layer is measured by handheld XRF, which is 96.1%; the surface roughness Ra of the NiAl-based bonding layer is 1.1μm.

[0095] Step 3: Preheating:

[0096] ① Install the guide blade on the turntable in the process chamber of the PS-PVD equipment, adjust the process chamber to an inert atmosphere and a vacuum degree of 200Pa; adjust the speed of the turntable to 70rpm, and the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m.

[0097] ② Adjust the spray gun to preheat the NiAl-based bonding layer with input powers of 20 kW, 40 kW and 60 kW in sequence, with each power level preheating for 2 minutes.

[0098] Step 4: Pre-oxidation treatment: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; introduce Ar30slpm, He60slpm and O22 slpm into the process chamber, adjust the spray deposition current of the spray gun to 2000A, and ventilate for 20s.

[0099] Step 5: Preparation of ceramic layer: Keep the rotation speed of the turntable at 70rpm, the robot drives the spray gun to swing up and down 40mm, the swing rate is 100mm / s, and the spraying distance is 1.2m; at the same time, continue to introduce Ar30slpm, He60slpm and O22 slpm into the process chamber, and the spray deposition current of the spray gun is maintained at 2000A; adopt a double-sided powder feeding method, and the powder feeding amount is 2×5g / min, and run according to the above parameters until the specified spraying time.

[0100] Step 6: Cooling treatment: adjust the spray gun to cool the NiAl-based bonding layer and the ceramic layer with input powers of 60kW, 40kW and 20kW in turn, wherein each power level is cooled for 2 minutes until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining a thermal barrier coating and forming an α-alumina TGO layer between the ceramic layer and the NiAl-based bonding layer; inflate, open the process chamber and take out the guide vanes.

[0101] The guide vane with thermal barrier coating prepared in Example 4 was placed in a muffle furnace and heated to 1100° C., kept warm for 5 to 10 minutes, and water quenched in pure water at 20±5° C. After 60 reciprocating cycles, there was no obvious peeling of the coating.

[0102] Figure 8 The cross-sectional fluorescence spectrum analysis and fitting peak analysis results of the thermal barrier coating prepared according to Example 4 of the present invention are shown in FIG. Figure 8 As shown, the four waves are the cross-sectional test wave, fitting wave, sub-wave 1 of the fitting wave, and sub-wave 2 of the fitting wave of the thermal barrier coating prepared in Example 4. The R2 standard peak of α-alumina is located at 14430.4 cm -1 The R2 peak of the α-alumina TGO layer in the thermal barrier coating is at 14430.6 cm -1 , and the deviation from the standard peak is extremely low, indicating that the residual stress introduced by the α-alumina TGO layer at the cross-sectional interface between the NiAl-based bonding layer and the 8YSZ ceramic layer is approximately zero.

[0103] Comparative Example:

[0104] Compared with Example 1, the comparative example lacks step 4, and the remaining operating steps, process parameters, etc. are the same as those of Example 1.

[0105] Figure 3 (b) is a cross-sectional morphology of the thermal barrier coating prepared according to the comparative example after being thermally cycled at 1100°C for 350 hours. Figure 3 (b) It can be seen that the alumina TGO layer formed at the interface of the NiAl-based bonding layer and the ceramic layer has a loose structure, poor density and poor continuity. The guide vane with thermal barrier coating prepared in the comparative example was placed in a muffle furnace and heated to 1100°C, kept warm for 5 to 10 minutes, and water quenched in pure water at 20±5°C. After 10 reciprocating cycles, slight peeling occurred, and its thermal shock performance was much lower than that of the thermal barrier coating prepared in Examples 1-4 of the present application.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a thermal barrier coating, characterized in that: The following steps are involved: Preparation of bonding layer: a single β-phase NiAl-based bonding layer is prepared on the surface of the substrate; Preheating treatment: the substrate is mounted in a process chamber of a PS-PVD device, and the NiAl-based bonding layer is preheated by using a spray gun in a vacuum inert atmosphere; Pre-oxidation treatment: introducing O2 into the process chamber, adjusting the spray gun to heat the NiAl-based bonding layer according to the spray deposition parameters; Preparation of ceramic layer: Keep O2 flowing into the process chamber, feed powder, and use the spray gun to spray and deposit the ceramic layer on the surface of the NiAl-based bonding layer with the spray deposition parameters; wherein a TGO layer of α-alumina is formed between the ceramic layer and the NiAl-based bonding layer; Cooling treatment: The NiAl-based bonding layer and the ceramic layer are subjected to cooling treatment to reduce the temperature to a preset temperature at a preset speed to obtain a thermal barrier coating.

2. The preparation method according to claim 1, characterized in that: In the preheating treatment step, the substrate is clamped on the turntable in the process chamber, and the process chamber is adjusted to an inert atmosphere and a vacuum degree of 200 Pa; the rotation speed of the turntable is adjusted to 60-80 rpm, and the manipulator drives the spray gun to swing up and down 30-50 mm, the swing rate is 90-110 mm / s, and the spraying distance is 1-1.4 m; the spray gun is adjusted to preheat the NiAl-based bonding layer with an input power of 15-25 kW, 35-45 kW and 55-65 kW in sequence, wherein each power level is preheated for 1.5-2.5 min.

3. The preparation method according to claim 1, characterized in that: In the pre-oxidation step, Ar, He and O2 are introduced into the process chamber, wherein the flow rate of Ar is 25-35slpm, and the flow rate of He is 55-65slpm, and both are used as plasma gas input for the spray gun; the flow rate of O2 is 2-4slpm, and is input from the top of the process chamber; the spray deposition current of the spray gun is adjusted to 1800-2200A, and the NiAl-based bonding layer is heated for 10-20s.

4. The preparation method according to claim 1, characterized in that: In the cooling treatment step, after the ceramic layer is spray-deposited, the spray gun is adjusted to cool the NiAl-based bonding layer and the ceramic layer with input powers of 55-65kW, 35-45kW and 15-25kW in sequence, wherein each power level is cooled for 1.5-2.5 minutes until the temperature of the NiAl-based bonding layer and the ceramic layer is cooled to below 500°C, thereby obtaining the thermal barrier coating.

5. The preparation method according to claim 1, characterized in that: The step of preparing the bonding layer includes: preparing a single β-phase NiAl-based bonding layer on the surface of the substrate by using a vapor phase infiltration technique, and performing a vacuum heat treatment at 950-1000° C. for 3-5 hours.

6. The preparation method according to claim 1, characterized in that: The step of preparing the bonding layer includes: using chemical vapor deposition technology to prepare a single β-phase NiAl-based bonding layer on the surface of the substrate.

7. The preparation method according to claim 1, characterized in that: The thickness of the NiAl-based bonding layer is in the range of 40 to 60 μm.

8. The preparation method according to claim 1, characterized in that: After the bonding layer preparation step, a surface roughening treatment step is also included: at a pressure of 0.2 to 0.3 MPa, the NiAl-based bonding layer is wet-sandblasted using 100 to 200 mesh white jade steel to make the surface roughness 0.9 to 1.3 μm, and the sum of the mass ratios of Ni and Al in the NiAl-based bonding layer is greater than 96%.

9. The preparation method according to claim 1, characterized in that: The ceramic layer is 8YSZ coating.

10. The preparation method according to claim 1, characterized in that: In the step of preparing the ceramic layer, a double-sided powder feeding method is adopted, and the powder feeding amount is 2×5 g / min.

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