High-toughness thermal barrier coating with gradually varied porosity gradient

Abstract

The invention belongs to the technical field of thermal barrier coatings, and particularly relates to a high-toughness thermal barrier coating with gradually varied porosity gradients. The invention provides a thermal barrier coating with gradually changed porosity gradient. The thermal barrier coating comprises a metal bonding layer and a ceramic layer arranged on the surface of the metal bonding layer, and the porosity of the ceramic layer is gradually increased from one end in contact with the metal bonding layer to the other end. The low-porosity ceramic layer region forms the ceramic layer compact bottom region, and the ceramic layer compact bottom region can effectively resist the damage of residual stress to the TC layer; the high-porosity ceramic layer area forms a ceramic layer porous top area, and the ceramic layer porous top area can effectively compensate strain caused by sintering, phase change and thermal mismatch under high-temperature impact. Therefore, according to the thermal barrier coating with the gradually-changed porosity gradient, the mechanical performance and the thermal performance are balanced, and the thermal barrier coating can be applied under the conditions of high temperature and strong scouring impact.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal barrier coatings, and in particular relates to a high-toughness thermal barrier coating with a gradual pore gradient. Background Art

[0002] At present, with the rapid development of aerospace technology, the inlet temperature of advanced aircraft engines and gas turbines continues to rise, which poses more stringent and urgent challenges to the operating temperature and service life of thermal barrier coatings (TBCs) on the surface of high-temperature hot end components.

[0003] Recently, the use temperature of coatings may reach 1500℃, which is higher than the use limit of traditional TBCs. Studies on TBCs have shown that one of the methods to improve the performance of TBCs under high temperature conditions is to prepare coating structures with high strain tolerance, such as dense vertical crack (DVC) TBCs and high porosity TBCs. Vertical cracks and pores reduce thermal stress during the manufacture and use of TBCs and improve thermal cycle life. However, the dense ceramic layer and vertical cracks of DVC TBCs promote the increase of thermal conductivity, limiting their application under high temperature conditions. The high porosity in high-porosity TBCs leads to insufficient bonding between ceramic powders, and then because the bonding strength of high-porosity TBCs cannot meet the requirements under strong gas impact, it limits its application under strong scouring impact conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a high-toughness thermal barrier coating with a gradual pore gradient. The thermal barrier coating with a gradual pore gradient provided by the present invention achieves a balance between mechanical properties and thermal properties, has good toughness, and can be used under high temperature and strong scour impact conditions.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The invention provides a thermal barrier coating with a gradual pore gradient, comprising a metal bonding layer and a ceramic layer arranged on the surface of the metal bonding layer; the porosity of the ceramic layer increases gradually from one end in contact with the metal bonding layer to the other end.

[0007] Preferably, the ceramic layer includes a first unit ceramic layer and a second unit ceramic layer, the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer is 300-400 μm, and the thickness of the second unit ceramic layer is 300-500 μm; the porosity of the first unit ceramic layer is 6-10%; the porosity of the second unit ceramic layer is 10-19%.

[0008] Preferably, the total porosity of the ceramic layer is 8-14.5%.

[0009] Preferably, the thickness of the ceramic layer is 700-850 μm.

[0010] Preferably, the material of the ceramic layer is yttria partially stabilized zirconia, and the molar percentage of yttria in the yttria partially stabilized zirconia is 6-8%.

[0011] Preferably, the material of the metal bonding layer includes NiCoCrAlY and / or NiCrAlY; the thickness of the metal bonding layer is 100-200 μm.

[0012] The present invention provides a method for preparing a thermal barrier coating with a gradual pore gradient as described in the above technical solution, comprising the following steps:

[0013] The metal bonding layer is prepared on the surface of the substrate by using the metal bonding layer raw material powder;

[0014] A ceramic layer is prepared on the surface of the metal bonding layer by using ceramic layer raw material powder, and the thermal barrier coating with gradual pore gradient is obtained on the surface of the substrate.

[0015] Preferably, the preparation method of the metal bonding layer and the ceramic layer is a plasma spraying method, and the conditions of the plasma spraying method include: the carrier gas flow rate of the metal bonding layer raw material powder and the ceramic layer raw material powder is independently 2-8NLPM; the current is independently 200-500A; the working gas includes a main gas and a secondary gas, the main gas is argon, and the flow rate of the main gas is independently 10-40NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is independently 1-6NLPM; the powder feeding rate is independently 10-40g / min; the spraying speed is independently 400-1000mm / s, and the spraying distance is independently 20-100mm; the working power of the spray gun is independently 10-36kW.

[0016] Preferably, the raw material powder of the metal bonding layer includes NiCoCrAl powder and / or NiCrAlY powder; the average particle size of the raw material powder of the metal bonding layer is 30 to 40 μm;

[0017] The raw material powder of the ceramic layer is yttria-partially stabilized zirconium oxide powder; the average particle size of the raw material powder of the ceramic layer is 30-50 μm.

[0018] Preferably, the substrate is a nickel-based high-temperature alloy substrate, and the nickel-based high-temperature alloy substrate includes a cast nickel-based high-temperature alloy substrate, a directionally solidified nickel-based high-temperature alloy substrate or a single crystal nickel-based high-temperature alloy substrate.

[0019] The present invention provides a thermal barrier coating with a gradual pore gradient, comprising a metal bonding layer and a ceramic (TC) layer arranged on the surface of the metal bonding layer; the porosity of the ceramic layer increases gradually from one end in contact with the metal bonding layer to the other end. The present invention forms a thermal barrier coating with a gradual pore gradient by increasing the porosity of the ceramic layer from one end in contact with the metal bonding layer to the other end, wherein the ceramic layer region with a low porosity forms a dense bottom region of the ceramic layer, and the dense bottom region of the ceramic layer can effectively resist the damage of the residual stress to the TC layer; the ceramic layer region with a high porosity forms a porous top region of the ceramic layer, and the porous top region of the ceramic layer can effectively compensate for the strain caused by sintering, phase change and thermal mismatch under high temperature impact; thus, the thermal barrier coating with a gradual pore gradient provided by the present invention achieves the dual advantages of mechanical properties and thermal properties, and the bottom region of the ceramic layer, relying on the dense structure with low porosity, builds an indestructible barrier, effectively resists the potential damage of the residual stress to the TC layer, and ensures the stability of the structure. When faced with the severe test of high temperature environment, the porous top area of ​​gradient porous TBCs shows excellent strain capacity. This area can not only flexibly adapt to the deformation generated during sintering, but also effectively alleviate the strain caused by phase change and thermal mismatch, ensuring the stable performance of TBCs under high temperature impact. In summary, the thermal barrier coating with gradual pore gradient provided by the present invention achieves a balance between mechanical properties and thermal properties, and can be used under high temperature and strong scouring impact conditions.

[0020] Further, in the present invention, the ceramic layer includes a first unit ceramic layer and a second unit ceramic layer, the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer is 300-400 μm, and the thickness of the second unit ceramic layer is 300-500 μm; the porosity of the first unit ceramic layer is 6-10%; the porosity of the second unit ceramic layer is 10-19%. The total porosity of the ceramic layer is 8-14.5%. The thickness of the ceramic layer is 700-850 μm. The present invention can further optimize the structure of TBCs by reasonably setting the gradient change of the pore structure of the ceramic layer, thereby achieving a dual improvement in mechanical properties and thermal properties.

[0021] The results of the examples show that the bonding strength between the thermal barrier coating with a gradient pore size provided by the present invention and the substrate is 30-40 MPa, and a thermal shock test is carried out for 25 minutes under an oxyacetylene flame with a center temperature of 1500°C; the results show that the thermal barrier coating with a gradient pore size provided by the present invention has excellent thermal shock life and good bonding strength. Therefore, the thermal barrier coating with a gradient pore size provided by the present invention shows great application potential under extreme conditions of high temperature environment and strong scour impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the spraying steps of Examples 1 to 3 of the present invention;

[0023] Figure 2 Microscopic morphology of the thermal barrier coating with gradual pore gradient prepared in Example 1 of the present invention:

[0024] Figure 3 Microscopic morphology of the thermal barrier coating with gradual pore gradient prepared in Example 2 of the present invention:

[0025] Figure 4 Microscopic morphology of the thermal barrier coating with gradual pore gradient prepared in Example 3 of the present invention:

[0026] Figure 5 Schematic diagram of thermal shock experiment of thermal barrier coatings with gradual pore gradient prepared in Examples 1 to 3 of the present invention;

[0027] Figure 6 The macroscopic morphology pictures of the thermal barrier coatings with gradual pore gradient prepared in Examples 1 to 3 of the present invention before and after thermal shock;

[0028] Figure 7 Schematic diagram of the bonding strength test of thermal barrier coatings with gradual pore gradient prepared in Examples 1 to 3 of the present invention;

[0029] Figure 8 This is a microscopic morphology of the thermal barrier coating prepared in Comparative Example 1 of the present invention;

[0030] Fig. 9 The macroscopic morphology of the thermal barrier coating prepared in comparative example 1 of the present invention before and after the thermal shock test;

[0031] In the figure: 1 is a workbench, 2 is a substrate, 3 is an oxyacetylene flame gun, 4 is a thermal barrier coating, 5 is an infrared temperature measuring device, 6 is a force, 7 is a fixture, and 8 is an adhesive. DETAILED DESCRIPTION

[0032] The invention provides a thermal barrier coating with a gradual pore gradient, comprising a metal bonding layer and a ceramic layer arranged on the surface of the metal bonding layer; the porosity of the ceramic layer increases gradually from one end in contact with the metal bonding layer to the other end.

[0033] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0034] The thermal barrier coating with a gradual pore gradient provided by the present invention comprises a metal bonding layer. In the present invention, the material of the metal bonding layer preferably comprises NiCoCrAlY and / or NiCrAlY. The thickness of the metal bonding layer is preferably 100 to 200 μm, and in the embodiment, it can be 200 μm, 150 μm or 180 μm.

[0035] The thermal barrier coating with a gradual porosity gradient provided by the present invention comprises a ceramic layer arranged on the surface of the metal bonding layer. The porosity of the ceramic layer increases gradually from one end in contact with the metal bonding layer to the other end. In the present invention, the porosity of the ceramic layer increases gradually from one end in contact with the metal bonding layer to the other end, that is, the ceramic layer comprises n layers of unit ceramic layers stacked in sequence, n is a positive integer ≥ 2; the first layer of unit ceramic layer is in contact with the metal bonding layer, and the porosity of the first layer of unit ceramic layer is < the porosity of the second layer of unit ceramic layer <... < the porosity of the nth layer of unit ceramic layer. The ceramic layer provided by the present invention perfectly combines the dual advantages of mechanical properties and thermal properties. In the present invention, the thickness of the ceramic layer is preferably 700-850μm, and in the embodiment it can be 700μm or 850μm. The total porosity of the ceramic layer is preferably 8-14.5%, and in the embodiment it can be 8.15%, 14.21% or 10.13%.

[0036] In the present invention, the ceramic layer preferably includes a first unit ceramic layer (TC1) and a second unit ceramic layer (TC2), wherein the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer is 300-400 μm, and the thickness of the second unit ceramic layer is 300-500 μm; the porosity of the first unit ceramic layer is 6-10%; and the porosity of the second unit ceramic layer is 10-19%. The thickness of the first unit ceramic layer is preferably 300-400 μm, and in embodiments, it may be 300 μm, 400 μm or 350 μm. The thickness of the second unit ceramic layer is preferably 300-500 μm, and in embodiments, it may be 400 μm, 300 μm or 500 μm. The porosity of the first unit ceramic layer is preferably 6-10%, and in embodiments, it may be 6.15%, 9.96% or 8.50%. The porosity of the second unit ceramic layer is preferably 10-19%, and in the embodiments, it may be 10%, 18.56% or 14.46%.

[0037] In the present invention, the material of the ceramic layer is preferably yttria partially stabilized zirconium oxide (Y2O3 stabilized ZrO2, YSZ). The molar percentage of yttria in the yttria partially stabilized zirconium oxide is preferably 6-8%.

[0038] The thermal barrier coating with a gradual pore gradient provided by the present invention is preferably arranged on the surface of a high-temperature alloy substrate. The high-temperature alloy substrate is preferably a nickel-based high-temperature alloy substrate. The nickel-based high-temperature alloy substrate preferably includes a cast nickel-based high-temperature alloy substrate, a directionally solidified nickel-based high-temperature alloy substrate or a single crystal nickel-based high-temperature alloy substrate.

[0039] The present invention provides a method for preparing a thermal barrier coating with a gradual pore gradient as described in the above technical solution, comprising the following steps:

[0040] The metal bonding layer is prepared on the surface of the substrate by using the metal bonding layer raw material powder;

[0041] A ceramic layer is prepared on the surface of the metal bonding layer by using ceramic layer raw material powder, and the thermal barrier coating with gradual pore gradient is obtained on the surface of the substrate.

[0042] The present invention uses a metal bonding layer raw material powder to prepare a metal bonding layer on the surface of a substrate. In the present invention, the substrate is preferably a high-temperature alloy substrate, the high-temperature alloy substrate is preferably a nickel-based high-temperature alloy substrate, and the nickel-based high-temperature alloy substrate preferably includes a cast nickel-based high-temperature alloy substrate, a directionally solidified nickel-based high-temperature alloy substrate or a single-crystal nickel-based high-temperature alloy substrate. In a specific embodiment of the present invention, the substrate can specifically be a GH3230 high-temperature alloy or a GH4169 high-temperature alloy. The present invention preferably pre-treats the substrate. In the present invention, the pre-treatment preferably includes sandblasting, cleaning and drying. In a specific embodiment of the present invention, the pre-treatment preferably includes sandblasting, cleaning and drying in sequence. Or the pre-treatment preferably includes cleaning, drying and sandblasting in sequence. The sandblasting is preferably performed with white corundum, and the mesh number of the white corundum is preferably 60 meshes. The reagent used for the cleaning preferably includes acetone and ethanol, or the reagent used for the cleaning is preferably ethanol. The cleaning preferably includes: first immersing with acetone, and then ultrasonic cleaning with ethanol. Or the cleaning preferably includes: ultrasonic cleaning with ethanol. The present invention has no special requirements on the specific implementation of the drying.

[0043] In the present invention, the raw material powder of the metal bonding layer preferably includes NiCoCrAl powder and / or NiCrAlY powder. The average particle size of the raw material powder of the metal bonding layer is preferably 30 to 40 μm. In the present invention, the raw material powder of the metal bonding layer is preferably pre-dried, and the pre-drying temperature is preferably 100 to 120° C., and the time is preferably 8 to 12 hours.

[0044] In the present invention, the preparation method of the metal bonding layer is preferably a plasma spraying (APS) method, and in the embodiment, it is specifically an atmospheric plasma spraying method. The spray gun used in the plasma spraying method is Oerlikon Metco 11MB-2. The conditions of the plasma spraying method preferably include: the carrier gas of the raw material powder of the metal bonding layer is preferably argon. The carrier gas flow rate of the metal bonding layer raw material powder is preferably 2-8NLPM, and is specifically 4NLPM in the embodiment; the current is preferably 200-500A, and is specifically 320A in the embodiment; the working gas preferably includes a main gas and a secondary gas, the main gas is preferably argon, and the flow rate of the main gas is preferably 10-40NLPM, preferably 15-30NLPM, and is specifically 21NLPM in the embodiment; the secondary gas is preferably hydrogen, and the flow rate of the secondary gas is preferably 1-6NLPM, and can be 4NLPM in the embodiment; the powder feeding rate is preferably 10-40g / min, more preferably 15-35g / min, most preferably 16-30g / min, and can be 17.6g / min in the embodiment; the spraying speed (i.e., the movement speed of the spray gun) is preferably 400-1000mm / s, and can be 600mm / s in the embodiment, and the spraying distance is preferably 20-100mm, preferably 30-100mm, and can be 60mm in the embodiment. The working power of the spray gun is preferably 10-36 kW, more preferably 11-20 kW, and in the embodiment, it can be 13.8 kW.

[0045] After obtaining the metal bonding layer, the present invention uses a ceramic layer raw material powder to prepare a ceramic layer on the surface of the metal bonding layer, and obtains the thermal barrier coating with a gradual pore gradient on the surface of the substrate. In the present invention, the ceramic layer raw material powder is preferably a zirconium oxide powder partially stabilized by yttria; the average particle size of the ceramic layer raw material powder is preferably 30 to 50 μm. The molar percentage of yttria in the YSZ powder is preferably 6 to 8%. In an embodiment of the present invention, the source of the ceramic layer raw material powder is Metco 204NS. The present invention preferably pre-dries the ceramic layer raw material powder, and the pre-drying temperature is preferably 100 to 120°C, and the time is preferably 8 to 12 hours.

[0046] In the present invention, the preparation method of the ceramic layer is preferably a plasma spraying method, and the spray gun used in the plasma spraying method is 11MB-Metco. The conditions of the plasma spraying method preferably include: the carrier gas of the raw material powder of the ceramic layer is preferably argon. The carrier gas flow rate of the raw material powder of the ceramic layer is preferably 2-8NLPM; the current is preferably 200-500A; the working gas preferably includes a main gas and a secondary gas, the main gas is preferably argon, and the flow rate of the main gas is preferably 10-40NLPM; the secondary gas is preferably hydrogen, and the flow rate of the secondary gas is preferably 1-6NLPM; the powder feeding rate is preferably 10-40g / min; the spraying speed is preferably 400-1000mm / s, and the spraying distance is preferably 20-100mm, preferably 30-100mm. The working power of the spray gun is preferably 10-36kW.

[0047] The present invention preferably obtains a ceramic layer with a porosity gradient by changing the condition parameters of the plasma spraying.

[0048] In the present invention, the ceramic layer preferably includes a first unit ceramic layer ( TC1 ) and a second unit ceramic layer ( TC2 ), and the first unit ceramic layer is in contact with the metal adhesive layer.

[0049] In the present invention, the preparation method of the first unit ceramic layer is preferably plasma spraying, and the spray gun used in the plasma spraying is 11MB-Metco. The conditions of the plasma spraying method preferably include: the carrier gas of the raw material powder of the ceramic layer is preferably argon. The carrier gas flow rate of the ceramic layer raw material powder is preferably 2-8NLPM, and can be 4NLPM in the embodiment; the current is preferably 200-500A, preferably 400-450A, and can be 440A in the embodiment; the working gas preferably includes a main gas and a secondary gas, the main gas is preferably argon, and the flow rate of the main gas is preferably 10-40NLPM, more preferably 15-25NLPM, and can be 18NLPM or 20NLPM in the embodiment; the secondary gas is preferably hydrogen, and the flow rate of the secondary gas is preferably 1-6NLPM, and can be 4NLPM or 5NLPM in the embodiment; the powder feeding rate is preferably 10-40g / min, more preferably 25-35g / min, more preferably 25-30g / min, and can be 25.1g / min, 32.4g / min or 28.3g / min in the embodiment; the spraying speed is preferably 400-1000mm / s, and can be 600mm / s in the embodiment, and the spraying distance is preferably 20-100mm, preferably 30-100mm, and can be 60mm in the embodiment. The working power of the spray gun is preferably 10-36 kW, more preferably 23-25 ​​kW, and in the embodiment, it can be 23.8 kW or 24.3 kW.

[0050] In the present invention, the preparation method of the second unit ceramic layer is preferably a plasma spraying method, and the spray gun used in the plasma spraying method is 11MB-Metco. The conditions of the plasma spraying method preferably include: the carrier gas of the raw material powder of the ceramic layer is preferably argon. The carrier gas flow rate of the raw material powder of the ceramic layer is preferably 2-8NLPM, and it can be 4NLPM in the embodiment; the current is preferably 200-500A, more preferably 300-400A, and it can be 380A or 320A in the embodiment; the working gas preferably includes a main gas and a secondary gas, the main gas is preferably argon, and the flow rate of the main gas is preferably 10-40NLPM, more preferably 15-20NLPM, and it can be 15NLPM, 16NLPM or 18NLPM in the embodiment; the secondary gas is preferably hydrogen, and the flow rate of the secondary gas is preferably 1- 6NLPM, in the embodiment, it can be 3NLPM, 4NLPM or 5.5NLPM; the powder feeding rate is preferably 10-40g / min, more preferably 28-33g / min, in the embodiment, it can be 30.13g / min, 32.4g / min or 28.3g / min; the spraying speed is preferably 400-1000mm / s, preferably 500-700mm / s, in the embodiment, it can be 600mm / s, the spraying distance is preferably 20-100mm, preferably 30-80mm, in the embodiment, it can be 60mm. The working power of the spray gun is preferably 10-36kW, more preferably 14.5-23.5kW, in the embodiment, it can be 23.1kW, 19.5kW or 14.6kW.

[0051] In the present invention, during the preparation of the ceramic layer: the raw material powder of the ceramic layer is formed into a thermal barrier coating with a gradual pore gradient by controlling the heat input and the raw material powder feeding rate during the plasma spraying (APS) method.

[0052] The present invention aims to provide a method for preparing and applying a high-performance gradient porosity thermal barrier coating, which overcomes the technical defects of the above-mentioned traditional APSDVC structural coating and high-porosity coating. The thermal barrier coating with a gradual pore gradient (the porosity increases gradually from TC from bottom to top) provided by the present invention can achieve a trade-off between mechanical properties and thermal properties. The dense bottom region of the TC with low porosity can resist the damage to the TC layer by residual stress. Under high-temperature impact, the porous top region of the TC compensates for the strain caused by sintering, phase change and thermal mismatch. Due to the combination of the above advantages, TBCs with a gradual pore gradient are expected to be used under high temperature and strong scour impact conditions.

[0053] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0054] The following examples are based on Figure 1The spraying step is carried out, Figure 1 It is demonstrated that the metal bonding layer and the ceramic layer are sprayed sequentially using a Metco-11MB-2 spray gun in Examples 1 to 3 of the present invention.

[0055] Example 1

[0056] The present embodiment provides a thermal barrier coating with a gradual porosity gradient, comprising a metal bonding layer arranged on the surface of a substrate and a ceramic layer arranged on the surface of the metal bonding layer. Wherein: the substrate is a GH3230 high temperature alloy or a GH4169 high temperature alloy. The metal bonding layer is a NiCrCoAlY metal bonding layer or a NiCrAlY metal bonding layer, and the thickness of the metal bonding layer is 200μm. The ceramic layer comprises a first unit ceramic layer and a second unit ceramic layer, and the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer (TC1) is 300μm, and the thickness of the second unit ceramic layer (TC2) is 400μm; the porosity of the first unit ceramic layer is 6.15%; the porosity of the second unit ceramic layer is 10%, the total thickness of the ceramic layer is 700μm, the total porosity is 8.15%, and the material of the ceramic layer is YSZ.

[0057] The method for preparing a thermal barrier coating with a gradual pore gradient provided in this embodiment comprises the following steps:

[0058] The wafer substrate is obtained by wire cutting and polishing, and the diameter of the wafer substrate is 40mm or 25.4mm and the thickness is 3mm. Figure 1 As shown, the surface of the wafer substrate is firstly sandblasted with 60 mesh white corundum, then fully ultrasonically cleaned with alcohol, and finally dried.

[0059] Subsequently, NiCrCoAlY metal powder or NiCrAlY metal powder is used to prepare a metal bonding layer by atmospheric plasma spraying on the surface of the wafer substrate. The average particle size of the NiCrCoAlY metal powder or NiCrAlY metal powder used is 30-40 μm. Before use, the NiCrCoAlY metal powder or NiCrAlY metal powder is pre-dried at a pre-drying temperature of 120° C. for 12 hours. The conditions for preparing the metal bonding layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of NiCrCoAlY metal powder or NiCrAlY metal powder is 4NLPM, and the current is 320A; the working gas includes a main gas and a secondary gas, the main gas is argon, and the flow rate of the main gas is 21NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 4NLPM; the powder feeding rate is 17.6g / min; the spraying speed (i.e., the spray gun moving speed) is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 13.8kW.

[0060] Finally, YSZ powder (Metco 204NS) was used to prepare a ceramic layer by atmospheric plasma spraying on the surface of the metal bonding layer. The average particle size of the YSZ powder used was 30-50 μm. Before use, the YSZ powder was pre-dried at a temperature of 120°C for 12 hours.

[0061] The conditions for preparing the first ceramic unit layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of YSZ powder is 4NLPM, and the current is 440A; the working gas includes main gas and secondary gas, the main gas is argon, and the flow rate of the main gas is 18NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 4NLPM; the powder feeding rate is 25.1g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 23.8kW.

[0062] The conditions for preparing the second ceramic unit layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of YSZ powder is 4NLPM, and the current is 440A; the working gas includes main gas and secondary gas, the main gas is argon, and the flow rate of the main gas is 15NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 3NLPM; the powder feeding rate is 30.13g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 23.1kW.

[0063] Figure 2 Microscopic morphology of the thermal barrier coating with gradual pore gradient prepared in Example 1 of the present invention: Figure 2 The bottom layer is the substrate, the metal bonding layer is in contact with the surface of the substrate, and the gradient porous ceramic layer is located on the surface of the metal bonding layer. The thickness of the metal bonding layer prepared in Example 1 is 200 μm, and the thickness of the gradient porous YSZ ceramic layer prepared in Example 1 is 700 μm; the porosity gradually increases from 6.15% of the lower coating TC1 (300 μm) to 10% of the upper coating TC2 (400 μm). The total porosity of the coating is 8.15%.

[0064] Example 2

[0065] The present embodiment provides a thermal barrier coating with a gradual porosity gradient, comprising a metal bonding layer arranged on the surface of a substrate and a ceramic layer arranged on the surface of the metal bonding layer. Wherein: the substrate is a GH3230 high temperature alloy or a GH4169 high temperature alloy. The metal bonding layer is a NiCrCoAlY metal bonding layer or a NiCrAlY metal bonding layer, and the thickness of the metal bonding layer is 150 μm. The ceramic layer comprises a first unit ceramic layer and a second unit ceramic layer, and the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer (TC1) is 400 μm, and the thickness of the second unit ceramic layer (TC2) is 300 μm; the porosity of the first unit ceramic layer is 9.96%; the porosity of the second unit ceramic layer is 18.56%, the total thickness of the ceramic layer is 700 μm, the total porosity is 14.21%, and the material of the ceramic layer is YSZ.

[0066] The method for preparing a thermal barrier coating with a gradual pore gradient provided in this embodiment comprises the following steps:

[0067] The wafer substrate is obtained by wire cutting and polishing, and the diameter of the wafer substrate is 40mm or 25.4mm and the thickness is 3mm. Figure 1 As shown, the surface of the wafer substrate is firstly sandblasted with 60 mesh white corundum, then fully ultrasonically cleaned with alcohol, and finally dried.

[0068] Subsequently, NiCrCoAlY metal powder or NiCrAlY metal powder is used to prepare a metal bonding layer by atmospheric plasma spraying on the surface of the wafer substrate. The average particle size of the NiCrCoAlY metal powder or NiCrAlY metal powder used is 30-40 μm. Before use, the NiCrCoAlY metal powder or NiCrAlY metal powder is pre-dried at a pre-drying temperature of 120° C. for 12 hours. The conditions for preparing the metal bonding layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of NiCrCoAlY metal powder or NiCrAlY metal powder is 4NLPM, and the current is 320A; the working gas includes a main gas and a secondary gas, the main gas is argon, and the flow rate of the main gas is 21NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 4NLPM; the powder feeding rate is 17.6g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 13.8kW.

[0069] Finally, YSZ powder (Metco 204NS) was used to prepare a ceramic layer by atmospheric plasma spraying on the surface of the metal bonding layer. The average particle size of the YSZ powder used was 30-50 μm. Before use, the YSZ powder was pre-dried at a temperature of 120°C for 12 hours.

[0070] The conditions for preparing the first ceramic unit layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of YSZ powder is 4NLPM, and the current is 440A; the working gas includes main gas and secondary gas, the main gas is argon, and the flow rate of the main gas is 18NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 5NLPM; the powder feeding rate is 32.4g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 24.3kW.

[0071] The conditions for preparing the second ceramic unit layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of YSZ powder is 4NLPM, and the current is 380A; the working gas includes main gas and secondary gas, the main gas is argon, and the flow rate of the main gas is 16NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 4NLPM; the powder feeding rate is 32.4g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 19.5kW.

[0072] Figure 3 Microscopic morphology of the thermal barrier coating with gradual pore gradient prepared in Example 2 of the present invention: Figure 3 The bottom layer is a metal bonding layer, and the gradient porous ceramic layer is located on the surface of the metal bonding layer. The thickness of the gradient porous YSZ ceramic layer prepared in this embodiment is 700 μm; the total porosity of the coating is 14.21%. The porosity of the lower coating TC1 (400 μm) is 9.96%. The porosity of the upper coating TC2 (300 μm) is 18.56%.

[0073] Example 3

[0074] The present embodiment provides a thermal barrier coating with a gradual porosity gradient, comprising a metal bonding layer arranged on the surface of a substrate and a ceramic layer arranged on the surface of the metal bonding layer. Wherein: the substrate is a GH3230 high temperature alloy or a GH4169 high temperature alloy. The metal bonding layer is a NiCrCoAlY metal bonding layer or a NiCrAlY metal bonding layer, and the thickness of the metal bonding layer is 180 μm. The ceramic layer comprises a first unit ceramic layer and a second unit ceramic layer, and the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer (TC1) is 350 μm, and the thickness of the second unit ceramic layer (TC2) is 500 μm; the porosity of the first unit ceramic layer is 8.5%; the porosity of the second unit ceramic layer is 14.46%, the total thickness of the ceramic layer is 850 μm, the total porosity is 10.13%, and the material of the ceramic layer is YSZ.

[0075] The method for preparing a thermal barrier coating with a gradual pore gradient provided in this embodiment comprises the following steps:

[0076] The wafer substrate is obtained by wire cutting and polishing, and the diameter of the wafer substrate is 40mm or 25.4mm and the thickness is 3mm. Figure 1 As shown, the surface of the wafer substrate is firstly sandblasted with 60 mesh white corundum, then fully ultrasonically cleaned with alcohol, and finally dried.

[0077] Subsequently, NiCrCoAlY metal powder or NiCrAlY metal powder is used to prepare a metal bonding layer by atmospheric plasma spraying on the surface of the wafer substrate. The average particle size of the NiCrCoAlY metal powder or NiCrAlY metal powder used is 30-40 μm. Before use, the NiCrCoAlY metal powder or NiCrAlY metal powder is pre-dried at a pre-drying temperature of 120° C. for 12 hours. The conditions for preparing the metal bonding layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of NiCrCoAlY metal powder or NiCrAlY metal powder is 4NLPM, and the current is 320A; the working gas includes a main gas and a secondary gas, the main gas is argon, and the flow rate of the main gas is 21NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 4NLPM; the powder feeding rate is 17.6g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 13.8kW.

[0078] Finally, YSZ powder (Metco 204NS) was used to prepare a ceramic layer by atmospheric plasma spraying on the surface of the metal bonding layer. The average particle size of the YSZ powder used was 30-50 μm. Before use, the YSZ powder was pre-dried at a temperature of 120°C for 12 hours.

[0079] The conditions for preparing the first ceramic unit layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of YSZ powder is 4NLPM, and the current is 440A; the working gas includes main gas and secondary gas, the main gas is argon, and the flow rate of the main gas is 20NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 5NLPM; the powder feeding rate is 28.3g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 24.3kW.

[0080] The conditions for preparing the second ceramic unit layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of YSZ powder is 4NLPM, and the current is 320A; the working gas includes main gas and secondary gas, the main gas is argon, and the flow rate of the main gas is 18NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 5.5NLPM; the powder feeding rate is 28.3g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 14.6kW.

[0081] Figure 4 Microscopic morphology of the thermal barrier coating with gradual pore gradient prepared in Example 3 of the present invention: Figure 4 The bottom layer is a metal bonding layer, and the gradient porous ceramic layer is located on the surface of the metal bonding layer. The thickness of the gradient porous YSZ ceramic layer prepared in this embodiment is 850 μm; the total porosity of the coating is 10.13%. The porosity of the lower coating TC1 (350 μm) is 8.50%. The porosity of the upper coating TC2 (500 μm) is 14.46%.

[0082] Test Case

[0083] The working temperature of the TBCs with a gradual pore change prepared in Examples 1 to 3 of the present invention is 1200 to 1600°C, and the thermal shock life in this temperature range is significantly better than that of conventional APS porous TBCs. The thermal barrier coatings with a gradual pore change prepared in Examples 1 to 3 were subjected to a 1500°C thermal shock test. The schematic diagram of the device is shown in FIG. Figure 5 As shown, the sample to be tested is placed on the experimental platform, and the coating surface is heated for 25 minutes using an oxygen-acetylene flame spray gun. The center temperature of the coating surface is controlled to be no less than 1500°C by adjusting the flow of oxygen and acetylene. The center temperature of the coating is monitored with the help of an infrared camera. After 25 minutes, the sample is quickly placed in 25°C cold water, and then the sample is blown dry. The entire thermal shock cycle process lasts 3 times. The results after thermal shock are as follows Figure 6 , Figure 6 For Example 1 of the present invention ( Figure 6 TBC I), Example 2 ( Figure 6 TBC II), Example 3 ( Figure 6 Macroscopic morphology of thermal barrier coating with gradient pore size prepared by TBC III before and after thermal shock; Figure 6 It shows that the thermal barrier coatings with gradual pore gradient prepared in Examples 1 to 3 can withstand three 1500°C thermal shock tests and there is no failure behavior such as peeling on the coating surface after the thermal shock cycle.

[0084] In addition, if Figure 7As shown, the pore gradient thermal barrier coating samples prepared in Examples 1 to 3 were connected with an adhesive and a fixture, and the coating bonding strength test of the pore gradient thermal barrier coatings prepared in Examples 1 to 3 of the present invention was carried out according to GB / T 8642-2002 (the substrate material during the test was GH3230 high-temperature alloy, and the metal bonding layer in the thermal barrier coating was NiCrCoAlY metal bonding layer). The bonding strengths of the pore gradient thermal barrier coatings prepared in Example 1, Example 2 and Example 3 were 34.8 MPa, 31.7 MPa and 37.1 MPa, respectively, which proves that the pore gradient thermal barrier coatings prepared in the present invention show great application potential under extreme conditions of high temperature environment and strong scour impact.

[0085] Comparative Example 1

[0086] This comparative example provides a thermal barrier coating, comprising a metal bonding layer arranged on the surface of a substrate and a ceramic layer arranged on the surface of the metal bonding layer. Wherein: the substrate is a GH3230 high temperature alloy or a GH4169 high temperature alloy. The metal bonding layer is a NiCrCoAlY metal bonding layer, and the thickness of the metal bonding layer is 200 μm. The material of the ceramic layer is YSZ, the thickness is 750 μm, and the porosity is 14.68% (similar to the thickness and total porosity of the ceramic layer of the thermal barrier coating with a gradual pore gradient prepared in Example 2).

[0087] The preparation method of the thermal barrier coating provided in this comparative example comprises the following steps:

[0088] The wafer substrate is obtained by wire cutting and polishing, and the diameter of the wafer substrate is 40mm or 25.4mm and the thickness is 3mm. Figure 1 As shown, the surface of the wafer substrate is firstly sandblasted with 60 mesh white corundum, then fully ultrasonically cleaned with alcohol, and finally dried.

[0089] Subsequently, NiCrCoAlY metal powder or NiCrAlY metal powder is used to prepare a metal bonding layer by atmospheric plasma spraying on the surface of the wafer substrate. The average particle size of the NiCrCoAlY metal powder or NiCrAlY metal powder used is 30-40 μm. Before use, the NiCrCoAlY metal powder or NiCrAlY metal powder is pre-dried at a pre-drying temperature of 120° C. for 12 hours. The conditions for preparing the metal bonding layer by atmospheric plasma spraying include: the plasma spray gun uses OerlikonMetco 11MB-2, the carrier gas (argon) flow rate of NiCrCoAlY metal powder or NiCrAlY metal powder is 4NLPM, and the current is 320A; the working gas includes a main gas and a secondary gas, the main gas is argon, and the flow rate of the main gas is 21NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is 4NLPM; the powder feeding rate is 17.6g / min; the spraying speed is 600mm / s, and the spraying distance is 60mm; the working power of the spray gun is 13.8kW.

[0090] Finally, YSZ powder (Metco 204NS) was used to prepare a ceramic layer by atmospheric plasma spraying on the surface of the metal bonding layer. The average particle size of the YSZ powder used was 30-50 μm. Before use, the YSZ powder was pre-dried at a temperature of 120°C for 12 hours.

[0091] The conditions for preparing the ceramic layer by atmospheric plasma spraying include: the plasma spray gun uses Oerlikon Metco11MB-2, the carrier gas (argon) flow rate of YSZ powder is 2.6NLPM, the current is 320A; the working gas includes main gas and secondary gas, the main gas is argon, the main gas flow rate is 16.2NLPM; the secondary gas is hydrogen, the secondary gas flow rate is 4.5NLPM; the powder feeding rate is 15.3g / min; the spraying speed is 600mm / s, the spraying distance is 60mm; the working power of the spray gun is 13.4kW. The thickness of the ceramic layer is 750μm. The microscopic morphology of the thermal barrier coating prepared in this comparative example is shown in FIG. Figure 8 As shown in Figure 2, the coating porosity is 14.68%. Figure 8 The bottom layer is the metal bonding layer, and the ceramic layer is located on the surface of the metal bonding layer. The performance of the thermal barrier coating prepared in Comparative Example 1 was tested according to the test methods of Examples 1 to 3 above. It can be found that although the thickness and total porosity of the ceramic layer in the thermal barrier coating prepared in Comparative Example 1 are basically the same as those of the ceramic layer in Example 2, the thermal barrier coating prepared in Comparative Example 1 has peeling failure on the coating surface after a thermal shock cycle of 1500°C for 25 minutes (such as Fig. 9 The coating prepared in Comparative Example 1 was subjected to a bonding strength test, and the bonding strength was only 12.31 MPa.

[0092] It can be seen from the above embodiments that the thermal barrier coating with a gradual pore gradient provided by the present invention overcomes the technical defects of traditional DVC structure coatings and high-porosity coatings. In the thermal barrier coating with a gradual pore gradient provided by the present invention, the porosity gradually increases from the TC layer from bottom to top, which can achieve a trade-off between mechanical properties and thermal properties. The low-porosity TC dense bottom region can resist the damage to the TC layer by residual stress. Under high-temperature impact, the porous top region of the TC compensates for the strain caused by sintering, phase change and thermal mismatch. Due to the combination of the above advantages, the thermal barrier coating with a gradual pore gradient provided by the present invention can be used under high temperature and strong scour impact conditions.

[0093] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A thermal barrier coating with a gradual pore gradient, characterized in that: It comprises a metal bonding layer and a ceramic layer arranged on the surface of the metal bonding layer; the porosity of the ceramic layer increases gradually from one end in contact with the metal bonding layer to the other end.

2. The thermal barrier coating with a gradual pore gradient according to claim 1, characterized in that: The ceramic layer includes a first unit ceramic layer and a second unit ceramic layer, the first unit ceramic layer is in contact with the metal bonding layer; the thickness of the first unit ceramic layer is 300-400 μm, and the thickness of the second unit ceramic layer is 300-500 μm; the porosity of the first unit ceramic layer is 6-10%; the porosity of the second unit ceramic layer is 10-19%.

3. The thermal barrier coating with a gradual pore gradient according to claim 1 or 2, characterized in that: The total porosity of the ceramic layer is 8-14.5%.

4. The thermal barrier coating with a gradual pore gradient according to claim 1 or 2, characterized in that: The thickness of the ceramic layer is 700-850 μm.

5. The thermal barrier coating with a gradual pore gradient according to claim 1, characterized in that: The material of the ceramic layer is yttria partially stabilized zirconium oxide, and the molar percentage of yttria in the yttria partially stabilized zirconium oxide is 6-8%.

6. The thermal barrier coating with a gradual pore gradient according to claim 1, characterized in that: The material of the metal bonding layer includes NiCoCrAlY and / or NiCrAlY; the thickness of the metal bonding layer is 100-200 μm.

7. The method for preparing a thermal barrier coating with a gradual pore gradient according to any one of claims 1 to 6, characterized in that: The following steps are involved: The metal bonding layer is prepared on the surface of the substrate by using the metal bonding layer raw material powder; A ceramic layer is prepared on the surface of the metal bonding layer by using ceramic layer raw material powder, and the thermal barrier coating with gradual pore gradient is obtained on the surface of the substrate.

8. The preparation method according to claim 7, characterized in that: The preparation method of the metal bonding layer and the ceramic layer is a plasma spraying method, and the conditions of the plasma spraying method include: the carrier gas flow rate of the metal bonding layer raw material powder and the ceramic layer raw material powder is independently 2-8NLPM; the current is independently 200-500A; the working gas includes a main gas and a secondary gas, the main gas is argon, and the flow rate of the main gas is independently 10-40NLPM; the secondary gas is hydrogen, and the flow rate of the secondary gas is independently 1-6NLPM; the powder feeding rate is independently 10-40g / min; the spraying speed is independently 400-1000mm / s, and the spraying distance is independently 20-100mm; the working power of the spray gun is independently 10-36kW.

9. The preparation method according to claim 7 or 8, characterized in that: The raw material powder of the metal bonding layer includes NiCoCrAl powder and / or NiCrAlY powder; the average particle size of the raw material powder of the metal bonding layer is 30-40 μm; The raw material powder of the ceramic layer is yttria-partially stabilized zirconium oxide powder; the average particle size of the raw material powder of the ceramic layer is 30-50 μm.

10. The preparation method according to claim 7, characterized in that: The substrate is a nickel-based high-temperature alloy substrate, and the nickel-based high-temperature alloy substrate includes a cast nickel-based high-temperature alloy substrate, a directionally solidified nickel-based high-temperature alloy substrate or a single crystal nickel-based high-temperature alloy substrate.

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