Dredging type thermal protection coating and preparation method thereof

Abstract

The invention provides a dredging type thermal protection coating and a preparation method thereof, and relates to the technical field of material surface engineering. The dredging type thermal protection coating comprises a heat conduction metal layer formed on the surface of a base body; the first intermediate layer is formed on the surface of the heat-conducting metal layer, and the first intermediate layer is an Al2O3-TiO2 composite coating doped with a first heat-conducting metal material; the second intermediate layer is formed on the surface of the first intermediate layer, and the second intermediate layer is a Gd2O3-Yb2O3-YSZ composite coating doped with a second heat conduction metal material; the surface layer is formed on the surface of the second middle layer, and the surface layer is an Sc2O3-Y2O3-ZrO2 composite coating doped with a third heat conduction metal material. The thermal protection performance of the coating can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of materials surface engineering technology, and more specifically, to a conductive thermal protective coating and its preparation method. Background Technology

[0002] With the rapid development of aerospace, advanced propulsion systems, and high-energy equipment technologies, thermal protection under extreme high-temperature environments has increasingly become a key bottleneck restricting the improvement of equipment performance and reliable operation. In applications such as aerodynamic hot-end components of hypersonic vehicles (e.g., wing leading edges, nose cones, control surfaces), rocket engine combustion chambers and nozzles, hypersonic ramjet engine inlets and combustion chambers, reusable spacecraft thermal protection systems, heat dissipation substrates for high-power-density electronic equipment, and the first wall of nuclear / fusion devices, the surfaces of components are subjected to instantaneous or continuous ultra-high heat flux densities (up to several MW / m³). 2 It has a large scale, a severe temperature gradient (>2000K) and a harsh thermo-mechanical-chemical (oxidation, ablation) coupled environment.

[0003] Existing thermal protection strategies mainly rely on heat-insulating coatings. The core mechanism is to use the extremely low thermal conductivity of the material itself to form a thermal barrier layer between the heated component and the high-temperature environment, thereby delaying the transfer of heat to the substrate material as much as possible.

[0004] However, when faced with extreme coupled conditions such as ultra-high temperature, high heat flux, strong erosion, and large thermal shock, these coatings are prone to a series of coating failure problems, such as melting, sintering, accelerated oxidation, volatilization, and peeling.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this disclosure is to provide a conductive thermal protective coating and its preparation method, thereby overcoming, to at least to some extent, the problem of thermal protection failure caused by insufficient coating performance.

[0007] According to a first aspect of this disclosure, a thermally conductive protective coating is provided, comprising: a thermally conductive metal layer formed on the surface of a substrate; a first intermediate layer formed on the surface of the thermally conductive metal layer, the first intermediate layer being an Al2O3-TiO2 composite coating doped with a first thermally conductive metal material; a second intermediate layer formed on the surface of the first intermediate layer, the second intermediate layer being a Gd2O3-Yb2O3-YSZ composite coating doped with a second thermally conductive metal material; and a surface layer formed on the surface of the second intermediate layer, the surface layer being a Sc2O3-Y2O3-ZrO2 composite coating doped with a third thermally conductive metal material.

[0008] Optionally, the material of the heat-conducting metal layer is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; the first heat-conducting metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; the second heat-conducting metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; and the third heat-conducting metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy.

[0009] Optionally, the first thermally conductive metal material, the second thermally conductive metal material, and the third thermally conductive metal material are of the same material type.

[0010] Optionally, the metal phase content of the first intermediate layer is greater than that of the surface layer, and the porosity of the first intermediate layer is less than that of the surface layer.

[0011] Optionally, the doping amount of the first thermally conductive metal material in the first intermediate layer is greater than 50 wt% and less than or equal to 70 wt%; the doping amount of the second thermally conductive metal material in the second intermediate layer is greater than 25 wt% and less than or equal to 50 wt%; and the doping amount of the third thermally conductive metal material in the surface layer is greater than 5 wt% and less than or equal to 25 wt%.

[0012] Optionally, the porosity of the thermally conductive metal layer is less than or equal to 5%; the porosity of the first intermediate layer is greater than 3% and less than or equal to 5%; the porosity of the second intermediate layer is greater than 5% and less than or equal to 8%; and the porosity of the surface layer is greater than 8% and less than or equal to 15%.

[0013] According to a second aspect of this disclosure, a method for preparing a conductive thermal protective coating is provided, used to prepare any of the aforementioned conductive thermal protective coatings. Specifically, the preparation method includes: doping a first thermally conductive metal material into an Al2O3-TiO2 ceramic material to obtain a first powder; doping a second thermally conductive metal material into a Gd2O3-Yb2O3-YSZ ceramic material to obtain a second powder; doping a third thermally conductive metal material into a Sc2O3-Y2O3-ZrO2 ceramic material to obtain a third powder; forming a thermally conductive metal layer on the surface of a substrate by plasma spraying; coating the surface of the thermally conductive metal layer with the first powder to form a first intermediate layer; coating the surface of the first intermediate layer with the second powder to form a second intermediate layer; and coating the surface of the second intermediate layer with the third powder to form a top layer.

[0014] Optionally, the process parameters for forming the thermally conductive metal layer include: a spraying power of 35~55kW, a main gas flow rate of 40~150L / min, a powder feeding rate of 10~50g / min, and a spraying distance of 8~20cm.

[0015] Optionally, the process parameters for forming the first intermediate layer, the second intermediate layer, and / or the top layer include: a spraying power of 40~60kW, a main air flow rate of 40~150L / min, a powder feeding rate of 20~50g / min, and a spraying distance of 8~20cm.

[0016] Optionally, before forming the thermally conductive metal layer, the preparation method further includes: cleaning and drying the substrate, and roughening the surface of the substrate so that the surface roughness of the substrate is greater than or equal to 3.2 μm and less than or equal to 10 μm.

[0017] In an exemplary embodiment of this disclosure, the heat-conducting protective coating comprises, from the inside out, a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer. On one hand, the thermally conductive metal layer forms the base layer, breaking through the passive heat-blocking mode of traditional heat-insulating coatings, and can actively reduce local overheating of the substrate through lateral heat diffusion. On the other hand, the first intermediate layer includes an Al2O3-TiO2 composite coating, which serves as a heat expansion zone, enabling rapid lateral heat conduction and uniform diffusion. Furthermore, the combination of Al2O3-TiO2 composite ceramic and the metal phase provides high hardness and toughness support while conducting heat. Furthermore, the second intermediate layer, as a transition zone, balances heat conduction and insulation, providing an effective temperature buffer for the top layer. Simultaneously, the Gd2O3-Yb2O3-YSZ ceramic material used in the second intermediate layer ensures high-temperature phase stability and low thermal conductivity in the transition zone. Finally, the top layer, as a heat-insulating functional zone, can maximally block heat flow, significantly improving the overall heat insulation performance of the heat-protective coating. Meanwhile, the Sc2O3-Y2O3-ZrO2 ceramic material used in the surface layer possesses high hardness, low thermal conductivity, and excellent high-temperature stability, ensuring the erosion resistance and long-term thermal insulation life of the thermal protective coating surface. In summary, the conductive thermal protective coating disclosed herein solves the technical problems of existing thermal insulation coatings in extreme high-temperature, high-heat-flux, and thermal shock environments, which lead to surface heat accumulation, localized overheating due to passive heat-insulating mechanisms, and consequently, coating melting, phase transformation, oxidation failure, and cracking and peeling due to large temperature gradients and thermal expansion mismatch.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0020] Figure 1 A schematic diagram of the structure of the heat-protective coating according to an embodiment of the present disclosure is shown.

[0021] Figure 2 A flowchart illustrating a method for preparing a heat-protective coating according to an embodiment of the present disclosure is shown.

[0022] Figure 3 A schematic diagram of the microstructure of the conductive thermal protective coating of Embodiment 1 of this disclosure is shown.

[0023] Figure 4 The force versus displacement curves are shown, which were measured to test the bonding strength of the conductive thermal protective coating of Embodiment 1 of this disclosure.

[0024] Figure 5 A schematic diagram showing the bonding strength and macroscopic morphology of the fracture interface of the conductive thermal protective coating of Embodiment 1 of this disclosure is shown.

[0025] Figure 6 A schematic diagram of the porosity of each layer in the conductive thermal protective coating of Embodiment 1 of this disclosure is shown. Detailed Implementation

[0026] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of these specific details omitted, or other methods, processes, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0027] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. The flowcharts shown in the drawings are merely exemplary illustrations and do not necessarily include all steps. For example, some steps may be broken down, while others may be combined or partially combined; therefore, the actual order of execution may change depending on the actual situation. Additionally, all terms such as "first," "second," and "third" below are for distinguishing purposes only and should not be construed as limiting the content of this disclosure.

[0028] Currently, thermal insulation coatings have limitations in dealing with extreme coupled conditions such as ultra-high temperatures, high heat flux, strong erosion, and large thermal shocks. These limitations mainly include the following two aspects: First, while thermal insulation coatings block heat transfer to the substrate, their own surface can reach extremely high temperatures due to heat accumulation. When the heat flux density is too high or the service life is extended, the surface temperature of the coating can easily exceed its melting point or undergo harmful phase transformations, leading to coating melting, sintering, accelerated oxidation, or volatilization failure. Second, the huge temperature difference between the coating surface and its interior (especially under thermal shock conditions) generates extremely high thermal stress. At the same time, the mismatch in the coefficient of thermal expansion (CTE) between the coating and the metal substrate can easily cause crack initiation, propagation, and even coating peeling at the interface.

[0029] To address or at least mitigate these problems, this disclosure provides a novel conductive thermal protective coating and its preparation method.

[0030] Figure 1 A schematic diagram of the structure of the heat-dissipating coating according to an embodiment of the present disclosure is shown. (Reference) Figure 1 The heat-conducting protective coating of this disclosure may include: a thermally conductive metal layer formed on the surface of a substrate, a first intermediate layer formed on the surface of the thermally conductive metal layer, a second intermediate layer formed on the surface of the first intermediate layer, and a surface layer formed on the surface of the second intermediate layer.

[0031] The thickness of the thermally conductive metal layer can be 30~80μm. The thickness of one or more of the first intermediate layer, second intermediate layer, and top layer can be 50~150μm.

[0032] In some embodiments of this disclosure, the thickness of the thermally conductive metal layer can be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm. The thickness of the first intermediate layer, the second intermediate layer, and / or the top layer can be 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, or 150 μm.

[0033] The first intermediate layer, the second intermediate layer, and the top layer are all made of ceramic materials doped with thermally conductive metals. Specifically, the first intermediate layer is an Al2O3-TiO2 composite coating doped with a first thermally conductive metal, the second intermediate layer is a Gd2O3-Yb2O3-YSZ composite coating doped with a second thermally conductive metal, and the top layer is a Sc2O3-Y2O3-ZrO2 composite coating doped with a third thermally conductive metal.

[0034] In exemplary embodiments of this disclosure, the material of the thermally conductive metal layer is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy. It is understood that in the field of alloys, Ni-Al alloy is an alloy composed of only nickel and aluminum, without specifying a particular element ratio, and is also known as a nickel-aluminum alloy. Similarly, Cu-Ni alloy is also known as a copper-nickel alloy, and Ni-Cr-Al alloy is also known as a nickel-chromium-aluminum alloy.

[0035] The first thermally conductive metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; the second thermally conductive metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; and the third thermally conductive metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy.

[0036] For example, in a Ni-coated Al alloy, the Ni content is 80 wt% and the Al content is 20 wt%. In a Cu-Ni alloy, the Cu content is 62 wt% and the Ni content is 38 wt%. In a Ni-Cr-Al alloy, the Ni content is 76.5 wt%, the Cr content is 18.5 wt%, and the Al content is 5 wt%. In an Al-coated Ni alloy, the Al content is 5 wt% and the Ni content is 95 wt%.

[0037] Specifically, for ease of raw material selection during preparation, the first, second, and third thermally conductive metal materials are of the same type. For example, they can all be Ni-Al alloys.

[0038] In addition, the metal phase content of the first intermediate layer is greater than that of the surface layer, and the porosity of the first intermediate layer is less than that of the surface layer.

[0039] Specifically, the doping amount of the first thermally conductive metal material in the first intermediate layer is greater than 50 wt% and less than or equal to 70 wt%; the doping amount of the second thermally conductive metal material in the second intermediate layer is greater than 25 wt% and less than or equal to 50 wt%; and the doping amount of the third thermally conductive metal material in the surface layer is greater than 5 wt% and less than or equal to 25 wt%.

[0040] For example, the doping amount of the first thermally conductive metal material in the first intermediate layer can be 55wt%, 60wt%, or 70wt%; the doping amount of the second thermally conductive metal material in the second intermediate layer can be 25.5wt%, 30wt%, or 50wt%; and the doping amount of the third thermally conductive metal material in the surface layer can be 5.5wt%, 15wt%, or 25wt%.

[0041] The porosity of the thermally conductive metal layer is less than or equal to 5%; the porosity of the first intermediate layer is greater than 3% and less than or equal to 5%; the porosity of the second intermediate layer is greater than 5% and less than or equal to 8%; and the porosity of the surface layer is greater than 8% and less than or equal to 15%.

[0042] For example, the porosity of the thermally conductive metal layer can be 5%, 4%, or 3%; the porosity of the first intermediate layer can be 3.5%, 4%, or 5%; the porosity of the second intermediate layer can be 5.5%, 6%, or 8%; and the porosity of the surface layer can be 8.5%, 12%, or 15%.

[0043] In the exemplary conductive thermal protective coating of this disclosure, the thermally conductive metal layer has a thermal conductivity greater than or equal to 10 W / (mK) at a temperature of 300°C, and the surface layer has a hardness greater than or equal to 800 HV. 0.3 The bonding strength is greater than or equal to 20 MPa.

[0044] When the substrate material covered by the heat-dissipating coating is titanium alloy, stainless steel, or aluminum alloy, under a constant heat source at 300℃, the temperature of the substrate covered by the heat-dissipating coating is less than or equal to 110℃. Or when the substrate material is nickel-based alloy or cobalt-based alloy, under an oxyacetylene flame at 1100℃, the thermal insulation temperature difference of the heat-dissipating coating is greater than or equal to 100℃. Under water quenching at 1100℃, the heat-dissipating coating undergoes more than or equal to 20 thermal shock cycles without peeling.

[0045] In an exemplary embodiment of this disclosure, the heat-conducting protective coating comprises, from the inside out, a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer. On one hand, the thermally conductive metal layer forms the base layer, breaking through the passive heat-blocking mode of traditional heat-insulating coatings, and can actively reduce local overheating of the substrate through lateral heat diffusion. On the other hand, the first intermediate layer includes an Al2O3-TiO2 composite coating, which can serve as a heat expansion zone. By combining the high metal phase content and low porosity of the first intermediate layer, rapid lateral heat conduction and uniform diffusion can be achieved. Furthermore, the combination of Al2O3-TiO2 composite ceramic and the metal phase provides high hardness and toughness support while conducting heat. On yet another hand, the second intermediate layer, as a transition zone, plays a role in balancing heat conduction and insulation, providing an effective temperature buffer for the top layer. Simultaneously, the Gd2O3-Yb2O3-YSZ ceramic material used in the second intermediate layer ensures high-temperature phase stability and low thermal conductivity in the transition zone. On the other hand, the surface layer, as a heat-insulating functional area, combined with controlled low metal content and high porosity, can maximally block heat flow and significantly improve the overall heat insulation performance of the thermal protective coating. Simultaneously, the Sc2O3-Y2O3-ZrO2 ceramic material used in the surface layer possesses high hardness, low thermal conductivity, and excellent high-temperature stability, ensuring the erosion resistance and long-term heat insulation life of the thermal protective coating surface. In summary, the conductive thermal protective coating disclosed herein solves the technical problems of existing heat-insulating coatings in extreme high-temperature, high-heat-flow, and thermal shock environments, such as surface heat accumulation, localized overheating due to passive heat-blocking mechanisms, and the resulting coating melting, phase transformation, oxidation failure, and cracking and peeling due to large temperature gradients and thermal expansion mismatch.

[0046] Figure 2 A flowchart illustrating a method for preparing a heat-resistant coating according to an embodiment of this disclosure is shown. (Reference) Figure 2 The method for preparing the conductive thermal protective coating according to the present disclosure may include the following steps: S20. Prepare powder.

[0047] Specifically, a first thermally conductive metal material is incorporated into Al2O3-TiO2 ceramic material to obtain a first powder; a second thermally conductive metal material is incorporated into Gd2O3-Yb2O3-YSZ ceramic material to obtain a second powder; and a third thermally conductive metal material is incorporated into Sc2O3-Y2O3-ZrO2 ceramic material to obtain a third powder.

[0048] S22. A thermally conductive metal layer is formed on the surface of the substrate by plasma spraying.

[0049] The particle size of the thermally conductive metal powder used to prepare the thermally conductive metal layer can be 15~53μm. The process parameters can include: spraying power of 35~55kW, main gas flow rate of 40~150L / min, powder feeding rate of 10~50g / min, and spraying distance of 8~20cm.

[0050] For example, the particle size of the thermally conductive metal powder can be 15μm, 35μm or 53μm; the spraying power can be 35kW, 45kW or 55kW; the main gas flow rate can be 40L / min, 100L / min or 150L / min; the powder feeding rate can be 10g / min, 30g / min or 50g / min; and the spraying distance can be 8cm, 15cm or 20cm.

[0051] Furthermore, before forming the thermally conductive metal layer, the substrate can be cleaned, dried, and its surface roughened to ensure that the surface roughness of the substrate is greater than or equal to 3.2 μm and less than or equal to 10 μm. For example, the surface roughness of the substrate can be 3.2 μm, 5 μm, 7 μm, 9 μm, or 10 μm.

[0052] S24. Coat the surface of the thermally conductive metal layer with a first powder to form a first intermediate layer.

[0053] S26. Coat the surface of the first intermediate layer with a second powder to form a second intermediate layer.

[0054] S28. Coat the surface of the second intermediate layer with a third powder to form a top layer.

[0055] The particle size of the first powder, the second powder, and / or the third powder can be 15~75μm.

[0056] The process parameters for forming the first intermediate layer, the second intermediate layer, and / or the top layer may include: a spraying power of 40~60kW, a main air flow rate of 40~150L / min, a powder feeding rate of 20~50g / min, and a spraying distance of 8~20cm.

[0057] For example, the particle size of the first powder, the second powder, and / or the third powder can be 15μm, 55μm, or 75μm; the spraying power can be 40kW, 50kW, or 60kW; the main air flow rate can be 40L / min, 100L / min, or 150L / min; the powder feeding rate can be 20g / min, 35g / min, or 50g / min; and the spraying distance can be 8cm, 15cm, or 20cm.

[0058] The following describes Embodiment 1 of this disclosure.

[0059] In a first aspect, Embodiment 1 provides a conductive thermal protection coating, which comprises, from the inside out, a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer. The thermally conductive metal layer is made of a Ni-coated Al alloy, the first intermediate layer is an Al2O3-TiO2 composite coating, the second intermediate layer is made of Gd2O3-Yb2O3-YSZ ceramic material, and the top layer is made of Sc2O3-Y2O3-ZrO2 ceramic material.

[0060] In this heat-conducting protective coating, the thickness of the thermally conductive metal layer is 30 μm, the thickness of the first intermediate layer is 60 μm, the thickness of the second intermediate layer is 70 μm, and the thickness of the top layer is 70 μm.

[0061] In this heat-conducting protective coating, the porosity of the thermally conductive metal layer is 3.8%, the porosity of the first intermediate layer is 4.3%, the porosity of the second intermediate layer is 6.5%, and the porosity of the surface layer is 8.2%.

[0062] In this heat-conducting protective coating, the first intermediate layer, the second intermediate layer, and the top layer are doped with a thermally conductive metal material, which is a Ni-coated Al alloy. The doping amount of the thermally conductive metal material in the first intermediate layer is 65 wt%, the doping amount in the second intermediate layer is 40 wt%, and the doping amount in the top layer is 15 wt%.

[0063] Secondly, Example 1 provides a method for preparing a conductive thermal protective coating, used to prepare the aforementioned conductive thermal protective coating. This preparation method includes steps 1 to 6 as described below.

[0064] In step 1, a substrate is obtained; in this embodiment, the substrate is a titanium alloy. The substrate is cleaned and dried, and then roughened using a sandblasting machine. After roughening the substrate surface using the sandblasting machine, the sandblasting pressure, distance, and angle are adjusted to achieve a surface roughness of 3.8 μm.

[0065] In step 2, powder preparation is performed. Based on the component ratios of the first intermediate layer, second intermediate layer, and surface layer described above, Ni-Al metal powder with a particle size of 15-53 μm and Al2O3-TiO2 ceramic powder with a particle size of 15-53 μm are mixed in a ball mill according to the corresponding proportions to obtain the first powder. Ni-Al metal powder with a particle size of 15-53 μm and Gd2O3-Yb2O3-YSZ powder with a particle size of 15-53 μm are mixed in a ball mill according to the corresponding proportions to obtain the second powder. Ni-Al metal powder with a particle size of 15-53 μm and Sc2O3-Y2O3-ZrO2 powder with a particle size of 15-53 μm are mixed in a ball mill according to the corresponding proportions to obtain the third powder.

[0066] In step 3, Ni-Al metal powder is sprayed onto the surface of the substrate using plasma spraying to form a thermally conductive metal layer. The particle size of the Ni-Al metal powder is 15~53μm. The plasma spraying process parameters in this step are: spraying power of 40kW, main gas flow rate of 45L / min, powder feed rate of 25g / min, and spraying distance of 12cm. The resulting metal-ceramic transition layer (i.e., the thermally conductive metal layer) has a thickness of 30μm and a porosity of 3.8%.

[0067] In step 4, a first powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a first intermediate layer. The process parameters for plasma spraying in this step are: spraying power of 42kW, main gas flow rate of 40L / min, powder feed rate of 25g / min, and spraying distance of 12cm. The prepared first intermediate layer has a thickness of 60μm and a porosity of 4.3%.

[0068] In step 5, a second powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying, forming a second intermediate layer on the surface of the first intermediate layer. The plasma spraying process parameters in this step are: spraying power of 45 kW, main gas flow rate of 45 L / min, powder feed rate of 35 g / min, and spraying distance of 12 cm. The resulting second intermediate layer has a thickness of 70 μm and a porosity of 6.5%.

[0069] In step 6, a third powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a top layer on the surface of the second intermediate layer. The process parameters for plasma spraying in this step are: spraying power of 48kW, main gas flow rate of 50L / min, powder feed rate of 35g / min, and spraying distance of 12cm. The resulting top layer has a thickness of 70μm and a porosity of 8.2%.

[0070] Figure 3 A schematic diagram illustrating the microstructure of the conductive thermal protective coating of Embodiment 1 of this disclosure is shown. (Reference) Figure 3 With the substrate 31 as the base, a thermally conductive metal layer 32, a first intermediate layer 33, a second intermediate layer 34, and a surface layer 35 are sequentially formed. Additionally, a resin layer 36 is formed on the surface layer 35 for subsequent mounting. Figure 3 As can be seen from the above, the conductive protective coating prepared in Example 1 of this disclosure has a tight bond between the layers, and there are no obvious boundaries or defects such as cracks.

[0071] Figure 4 The force versus displacement curves are shown, which were measured to test the bonding strength of the conductive thermal protective coating of Embodiment 1 of this disclosure. Figure 5A schematic diagram showing the bonding strength and macroscopic morphology of the fracture interface of the conductive thermal protective coating of Embodiment 1 of this disclosure is provided. Figure 4 and Figure 5 It can be seen that the bonding strength of 22.5 MPa between the coating and the substrate can be determined by dividing the maximum force by the cross-sectional area of ​​the tensile specimen.

[0072] Figure 6 A schematic diagram showing the porosity of each layer in the conductive thermal protective coating of Embodiment 1 of this disclosure is illustrated. See also Figure 6 In the conductive thermal protective coating of Embodiment 1 of this disclosure, the porosities of the thermally conductive metal layer, the first intermediate layer, the second intermediate layer and the surface layer are 3.8%, 4.3%, 6.5% and 8.2%, respectively, showing a gradually increasing trend.

[0073] Embodiment 2 of this disclosure will be described below.

[0074] In a first aspect, Example 2 provides a conductive thermal protection coating, which comprises, from the inside out, a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer. The thermally conductive metal layer is made of a Ni-coated Al alloy, the first intermediate layer is an Al2O3-TiO2 composite coating, the second intermediate layer is made of Gd2O3-Yb2O3-YSZ ceramic material, and the top layer is made of Sc2O3-Y2O3-ZrO2 ceramic material.

[0075] In this heat-conducting protective coating, the thickness of the thermally conductive metal layer is 50 μm, the thickness of the first intermediate layer is 50 μm, the thickness of the second intermediate layer is 50 μm, and the thickness of the top layer is 50 μm.

[0076] In this heat-conducting protective coating, the porosity of the thermally conductive metal layer is 3.5%, the porosity of the first intermediate layer is 3.7%, the porosity of the second intermediate layer is 5.4%, and the porosity of the surface layer is 8.6%.

[0077] In this heat-conducting protective coating, the first intermediate layer, the second intermediate layer, and the top layer are doped with a thermally conductive metal material, which is a Ni-coated Al alloy. The doping amount of the thermally conductive metal material in the first intermediate layer is 70 wt%, the doping amount in the second intermediate layer is 50 wt%, and the doping amount in the top layer is 25 wt%.

[0078] Secondly, Example 2 provides a method for preparing a conductive thermal protective coating, used to prepare the aforementioned conductive thermal protective coating. This preparation method includes steps 1 to 6 as described below.

[0079] In step 1, a substrate is obtained; in this embodiment, the substrate is a titanium alloy. The substrate is cleaned and dried, and then roughened using a sandblasting machine. After roughening the substrate surface using the sandblasting machine, the sandblasting pressure, distance, and angle are adjusted to achieve a surface roughness of 10 μm.

[0080] In step 2, powder preparation is performed. Based on the component ratios of the first intermediate layer, second intermediate layer, and surface layer described above, Ni-Al metal powder with a particle size of 15-45 μm and Al2O3-TiO2 ceramic powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the first powder. Ni-Al metal powder with a particle size of 15-45 μm and Gd2O3-Yb2O3-YSZ powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the second powder. Ni-Al metal powder with a particle size of 15-45 μm and Sc2O3-Y2O3-ZrO2 powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the third powder.

[0081] In step 3, Ni-Al metal powder is sprayed onto the surface of the substrate using plasma spraying to form a thermally conductive metal layer. The particle size of the Ni-Al metal powder is 15~45μm. The plasma spraying process parameters in this step are: spraying power of 35kW, main gas flow rate of 40L / min, powder feed rate of 10g / min, and spraying distance of 8cm. The resulting metal-ceramic transition layer (i.e., the thermally conductive metal layer) has a thickness of 50μm and a porosity of 3.5%.

[0082] In step 4, a first powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a first intermediate layer. The process parameters for plasma spraying in this step are: spraying power of 42kW, main gas flow rate of 70L / min, powder feed rate of 35g / min, and spraying distance of 8cm. The prepared first intermediate layer has a thickness of 50μm and a porosity of 3.7%.

[0083] In step 5, a second powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying, forming a second intermediate layer on the surface of the first intermediate layer. The plasma spraying process parameters in this step are: spraying power of 50kW, main gas flow rate of 120L / min, powder feed rate of 45g / min, and spraying distance of 12cm. The resulting second intermediate layer has a thickness of 50μm and a porosity of 5.4%.

[0084] In step 6, a third powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a top layer on the surface of the second intermediate layer. The plasma spraying process parameters in this step are: spraying power of 60kW, main gas flow rate of 150L / min, powder feed rate of 35g / min, and spraying distance of 20cm. The resulting top layer has a thickness of 50μm and a porosity of 8.6%.

[0085] Embodiment 3 of this disclosure will be described below.

[0086] In a first aspect, Example 3 provides a conductive thermal protection coating, which comprises, from the inside out, a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer. The thermally conductive metal layer is made of Cu-Ni alloy, the first intermediate layer is an Al2O3-TiO2 composite coating, the second intermediate layer is made of Gd2O3-Yb2O3-YSZ ceramic material, and the top layer is made of Sc2O3-Y2O3-ZrO2 ceramic material.

[0087] In this heat-conducting protective coating, the thickness of the thermally conductive metal layer is 80 μm, the thickness of the first intermediate layer is 50 μm, the thickness of the second intermediate layer is 100 μm, and the thickness of the top layer is 150 μm.

[0088] In this heat-conducting protective coating, the porosity of the thermally conductive metal layer is 4%, the porosity of the first intermediate layer is 5%, the porosity of the second intermediate layer is 8%, and the porosity of the surface layer is 15%.

[0089] In this conductive thermal protective coating, the first intermediate layer, the second intermediate layer, and the top layer are doped with a thermally conductive metal material, which is a Cu-Ni alloy. The doping amount of the thermally conductive metal material in the first intermediate layer is 55 wt%, the doping amount in the second intermediate layer is 30 wt%, and the doping amount in the top layer is 10 wt%.

[0090] Secondly, Example 3 provides a method for preparing a conductive thermal protective coating, used to prepare the aforementioned conductive thermal protective coating. This preparation method includes steps 1 to 6 as described below.

[0091] In step 1, a substrate is obtained; in this embodiment, the substrate is a titanium alloy. The substrate is cleaned and dried, and then roughened using a sandblasting machine. After roughening the substrate surface using the sandblasting machine, the sandblasting pressure, distance, and angle are adjusted to achieve a surface roughness of 5.6 μm.

[0092] In step 2, powder preparation is performed. Based on the component ratios of the first intermediate layer, second intermediate layer, and surface layer described above, Cu-Ni metal powder with a particle size of 15-45 μm and Al2O3-TiO2 ceramic powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the first powder. Cu-Ni metal powder with a particle size of 15-45 μm and Gd2O3-Yb2O3-YSZ powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the second powder. Cu-Ni metal powder with a particle size of 15-45 μm and Sc2O3-Y2O3-ZrO2 powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the third powder.

[0093] In step 3, Cu-Ni metal powder is sprayed onto the surface of the substrate using plasma spraying to form a thermally conductive metal layer. The particle size of the Cu-Ni metal powder is 15~45μm. The plasma spraying process parameters in this step are: spraying power of 35kW, main gas flow rate of 55L / min, powder feed rate of 20g / min, and spraying distance of 15cm. The resulting metal-ceramic transition layer (i.e., the thermally conductive metal layer) has a thickness of 80μm and a porosity of 4%.

[0094] In step 4, a first powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a first intermediate layer. The process parameters for plasma spraying in this step are: spraying power of 40kW, main gas flow rate of 80L / min, powder feed rate of 30g / min, and spraying distance of 15cm. The resulting first intermediate layer has a thickness of 50μm and a porosity of 5%.

[0095] In step 5, a second powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying, forming a second intermediate layer on the surface of the first intermediate layer. The plasma spraying process parameters in this step are: spraying power of 48kW, main gas flow rate of 100L / min, powder feed rate of 45g / min, and spraying distance of 15cm. The resulting second intermediate layer has a thickness of 100μm and a porosity of 8%.

[0096] In step 6, a third powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a top layer on the surface of the second intermediate layer. The plasma spraying process parameters in this step are: spraying power of 55kW, main gas flow rate of 120L / min, powder feed rate of 50g / min, and spraying distance of 15cm. The resulting top layer has a thickness of 150μm and a porosity of 15%.

[0097] Embodiment 4 of this disclosure will now be described.

[0098] In a first aspect, Example 4 provides a conductive thermal protection coating, which consists of a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer, arranged sequentially from the inside out. The thermally conductive metal layer is made of a Ni-Cr-Al alloy, the first intermediate layer is an Al2O3-TiO2 composite coating, the second intermediate layer is made of Gd2O3-Yb2O3-YSZ ceramic material, and the top layer is made of Sc2O3-Y2O3-ZrO2 ceramic material.

[0099] In this heat-conducting protective coating, the thickness of the thermally conductive metal layer is 60 μm, the thickness of the first intermediate layer is 60 μm, the thickness of the second intermediate layer is 90 μm, and the thickness of the top layer is 110 μm.

[0100] In this heat-conducting protective coating, the porosity of the thermally conductive metal layer is 3.2%, the porosity of the first intermediate layer is 4.1%, the porosity of the second intermediate layer is 7.6%, and the porosity of the surface layer is 12.6%.

[0101] In this conductive thermal protective coating, the first intermediate layer, the second intermediate layer, and the top layer are doped with a thermally conductive metal material, which is a Ni-Cr-Al alloy. The doping amount of the thermally conductive metal material in the first intermediate layer is 60 wt%, the doping amount in the second intermediate layer is 35 wt%, and the doping amount in the top layer is 5 wt%.

[0102] Secondly, Example 4 provides a method for preparing a conductive thermal protective coating, used to prepare the aforementioned conductive thermal protective coating. This preparation method includes steps 1 to 6 as described below.

[0103] In step 1, a substrate is obtained; in this embodiment, the substrate is a titanium alloy. The substrate is cleaned and dried, and then roughened using a sandblasting machine. After roughening the substrate surface using the sandblasting machine, the sandblasting pressure, distance, and angle are adjusted to achieve a surface roughness of 8.3 μm.

[0104] In step 2, powder preparation is performed. Based on the component ratios of the first intermediate layer, second intermediate layer, and surface layer described above, Ni-Cr-Al metal powder with a particle size of 15-53 μm and Al2O3-TiO2 ceramic powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the first powder. Ni-Cr-Al metal powder with a particle size of 15-53 μm and Gd2O3-Yb2O3-YSZ powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the second powder. Ni-Cr-Al metal powder with a particle size of 15-53 μm and Sc2O3-Y2O3-ZrO2 powder with a particle size of 15-45 μm are mixed in a ball mill according to the corresponding proportions to obtain the third powder.

[0105] In step 3, Ni-Cr-Al metal powder is sprayed onto the surface of the substrate using plasma spraying to form a thermally conductive metal layer. The particle size of the Ni-Cr-Al metal powder is 15~53μm. The plasma spraying process parameters in this step are: spraying power of 38kW, main gas flow rate of 55L / min, powder feed rate of 30g / min, and spraying distance of 12cm. The resulting metal-ceramic transition layer (i.e., the thermally conductive metal layer) has a thickness of 60μm and a porosity of 3.2%.

[0106] In step 4, a first powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a first intermediate layer. The process parameters for plasma spraying in this step are: spraying power of 45kW, main gas flow rate of 70L / min, powder feed rate of 25g / min, and spraying distance of 10cm. The prepared first intermediate layer has a thickness of 60μm and a porosity of 4.1%.

[0107] In step 5, a second powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying, forming a second intermediate layer on the surface of the first intermediate layer. The plasma spraying process parameters in this step are: spraying power of 55kW, main gas flow rate of 120L / min, powder feed rate of 40g / min, and spraying distance of 10cm. The resulting second intermediate layer has a thickness of 110μm and a porosity of 7.6%.

[0108] In step 6, a third powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a top layer on the surface of the second intermediate layer. The plasma spraying process parameters in this step are: spraying power of 56 kW, main gas flow rate of 120 L / min, powder feed rate of 50 g / min, and spraying distance of 15 cm. The resulting top layer has a thickness of 110 μm and a porosity of 12.6%.

[0109] Embodiment 5 of this disclosure will now be described.

[0110] In a first aspect, Example 5 provides a conductive thermal protection coating, which comprises, from the inside out, a thermally conductive metal layer, a first intermediate layer, a second intermediate layer, and a top layer. The thermally conductive metal layer is made of an Al-coated Ni alloy, the first intermediate layer is an Al2O3-TiO2 composite coating, the second intermediate layer is made of Gd2O3-Yb2O3-YSZ ceramic material, and the top layer is made of Sc2O3-Y2O3-ZrO2 ceramic material.

[0111] In this heat-conducting protective coating, the thickness of the thermally conductive metal layer is 30 μm, the thickness of the first intermediate layer is 70 μm, the thickness of the second intermediate layer is 120 μm, and the thickness of the top layer is 80 μm.

[0112] In this heat-conducting protective coating, the porosity of the thermally conductive metal layer is 4.3%, the porosity of the first intermediate layer is 4.7%, the porosity of the second intermediate layer is 6.8%, and the porosity of the surface layer is 10.3%.

[0113] In this conductive thermal protective coating, the first intermediate layer, the second intermediate layer, and the top layer are doped with a thermally conductive metal material, which is an Al-coated Ni alloy. The doping amount of the thermally conductive metal material in the first intermediate layer is 50 wt%, the doping amount in the second intermediate layer is 45 wt%, and the doping amount in the top layer is 20 wt%.

[0114] Secondly, Example 5 provides a method for preparing a conductive thermal protective coating, used to prepare the aforementioned conductive thermal protective coating. This preparation method includes steps 1 to 6 below.

[0115] In step 1, a substrate is obtained; in this embodiment, the substrate is a titanium alloy. The substrate is cleaned and dried, and then roughened using a sandblasting machine. After roughening the substrate surface using the sandblasting machine, the sandblasting pressure, distance, and angle are adjusted to achieve a surface roughness of 3.2 μm.

[0116] In step 2, powder preparation is performed. Based on the component ratios of the first intermediate layer, second intermediate layer, and surface layer described above, Al-coated Ni metal powder with a particle size of 15-53 μm and Al₂O₃-TiO₂ ceramic powder with a particle size of 15-75 μm are mixed in a ball mill according to the corresponding proportions to obtain the first powder. Al-coated Ni metal powder with a particle size of 15-53 μm and Gd₂O₃-Yb₂O₃-YSZ powder with a particle size of 15-75 μm are mixed in a ball mill according to the corresponding proportions to obtain the second powder. Al-coated Ni metal powder with a particle size of 15-53 μm and Sc₂O₃-Y₂O₃-ZrO₂ powder with a particle size of 15-75 μm are mixed in a ball mill according to the corresponding proportions to obtain the third powder.

[0117] In step 3, Al-coated Ni metal powder is sprayed onto the surface of the substrate using plasma spraying to form a thermally conductive metal layer. The particle size of the Al-coated Ni metal powder is 15~53μm. The plasma spraying process parameters in this step are: spraying power of 40kW, main gas flow rate of 40L / min, powder feed rate of 20g / min, and spraying distance of 15cm. The resulting metal-ceramic transition layer (i.e., the thermally conductive metal layer) has a thickness of 30μm and a porosity of 4.3%.

[0118] In step 4, a first powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying, forming a first intermediate layer on the surface of the thermally conductive metal layer. The process parameters for plasma spraying in this step are: spraying power of 50kW, main gas flow rate of 90L / min, powder feed rate of 20g / min, and spraying distance of 15cm. The prepared first intermediate layer has a thickness of 70μm and a porosity of 4.7%.

[0119] In step 5, a second powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying, forming a second intermediate layer on the surface of the first intermediate layer. The plasma spraying process parameters in this step are: spraying power of 60kW, main gas flow rate of 150L / min, powder feed rate of 50g / min, and spraying distance of 15cm. The resulting second intermediate layer has a thickness of 120μm and a porosity of 6.8%.

[0120] In step 6, a third powder is sprayed onto the surface of the thermally conductive metal layer using plasma spraying to form a top layer on the surface of the second intermediate layer. The plasma spraying process parameters in this step are: spraying power of 57kW, main gas flow rate of 120L / min, powder feed rate of 50g / min, and spraying distance of 15cm. The resulting top layer has a thickness of 80μm and a porosity of 10.3%.

[0121] The difference between Comparative Example 1 of this disclosure and Example 3 described above is that the materials of the first intermediate layer, the second intermediate layer, and the top layer are all Gd2O3-Yb2O3-YSZ ceramic materials. All other aspects are the same.

[0122] The difference between Comparative Example 2 of this disclosure and Example 2 described above is that the doping amount of the thermally conductive metal material in the first intermediate layer and the second intermediate layer is the same as that in the surface layer, which is 25 wt%. The rest are the same.

[0123] The difference between Comparative Example 3 of this disclosure and Embodiment 4 described above is that the porosity of the first intermediate layer and the second intermediate layer is the same as that of the surface layer, both being 12.6%. All other aspects are the same.

[0124] Furthermore, the thermal protective coatings prepared in the above embodiments and comparative examples were tested for thermal conductivity, surface hardness, and bonding strength at 300°C, and under a constant heat source at 300°C (heat flux density 0.3 MW / m³). 2 The substrate temperature covered by the coating is at 1100℃ in an oxyacetylene flame (heat flux density 2.0 MW / m³). 2 The lower coating can be used to test the thermal insulation temperature difference and thermal shock performance. The test results are shown in Table 1.

[0125] Table 1

[0126] As can be seen from Table 1 above, compared with Examples 1 to 3, Comparative Example 1 shows poor performance in all three indicators: thermal conductivity, surface hardness, and substrate temperature at 300℃. Compared with Examples 1 to 3, Comparative Example 2 shows a significant deterioration in the substrate temperature indicator. Compared with Examples 4 to 5, Comparative Example 3 shows significant deterioration in both the thermal insulation temperature difference and the thermal shock resistance of the coating at 1100℃. In other words, the solutions of this disclosure can improve the overall performance of the coating, and the coating performance can be controlled by adjusting the content of the metallic phase in the coating, the coating porosity, and the process parameters.

[0127] It should be noted that although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.

[0128] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this disclosure and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0129] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0130] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A heat-protective coating with a permeable structure, characterized in that, include: A thermally conductive metal layer formed on the surface of the substrate; A first intermediate layer is formed on the surface of the thermally conductive metal layer. The first intermediate layer is an Al2O3-TiO2 composite coating doped with a first thermally conductive metal material. The doping amount of the first thermally conductive metal material in the first intermediate layer is greater than 50 wt% and less than or equal to 70 wt%. A second intermediate layer is formed on the surface of the first intermediate layer. The second intermediate layer is a Gd2O3-Yb2O3-YSZ composite coating doped with a second thermally conductive metal material. The doping amount of the second thermally conductive metal material in the second intermediate layer is greater than 25 wt% and less than or equal to 50 wt%. A surface layer is formed on the surface of the second intermediate layer. The surface layer is a Sc2O3-Y2O3-ZrO2 composite coating doped with a third thermally conductive metal material. The doping amount of the third thermally conductive metal material in the surface layer is greater than 5wt% and less than or equal to 25wt%.

2. The heat-protective coating according to claim 1, characterized in that, The material of the thermally conductive metal layer is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; The first thermally conductive metal material is one or more of Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; The second thermally conductive metal material is one or more of the following: Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy; The third thermally conductive metal material is one or more of the following: Ni-Al alloy, Ni-coated Al alloy, Al-coated Ni alloy, Cu-Ni alloy, and Ni-Cr-Al alloy.

3. The conductive thermal protective coating according to claim 1 or 2, characterized in that, The metal phase content of the first intermediate layer is greater than that of the surface layer, and the porosity of the first intermediate layer is less than that of the surface layer.

4. The heat-protective coating according to claim 3, characterized in that, The porosity of the thermally conductive metal layer is less than or equal to 5%; The porosity of the first intermediate layer is greater than 3% and less than or equal to 5%; The porosity of the second intermediate layer is greater than 5% and less than or equal to 8%; The porosity of the surface layer is greater than 8% and less than or equal to 15%.

5. A method for preparing a conductive thermal protective coating, characterized in that, A method for preparing the conductive thermal protective coating according to any one of claims 1 to 4; the preparation method includes: A first thermally conductive metal material is incorporated into Al2O3-TiO2 ceramic material to obtain a first powder; a second thermally conductive metal material is incorporated into Gd2O3-Yb2O3-YSZ ceramic material to obtain a second powder; and a third thermally conductive metal material is incorporated into Sc2O3-Y2O3-ZrO2 ceramic material to obtain a third powder. A thermally conductive metal layer is formed on the surface of the substrate using plasma spraying. The first powder is coated on the surface of the thermally conductive metal layer to form a first intermediate layer; The second powder is coated onto the surface of the first intermediate layer to form a second intermediate layer; The third powder is coated onto the surface of the second intermediate layer to form a top layer.

6. The preparation method according to claim 5, characterized in that, The process parameters for forming the thermally conductive metal layer include: spraying power of 35~55kW, main gas flow rate of 40~150L / min, powder feeding rate of 10~50g / min, and spraying distance of 8~20cm.

7. The preparation method according to claim 5, characterized in that, The process parameters for forming the first intermediate layer, the second intermediate layer and / or the top layer include: spraying power of 40~60kW, main air flow rate of 40~150L / min, powder feeding rate of 20~50g / min, and spraying distance of 8~20cm.

8. The preparation method according to any one of claims 5 to 7, characterized in that, Before forming the thermally conductive metal layer, the preparation method further includes: The substrate is cleaned and dried, and the surface of the substrate is roughened so that the surface roughness of the substrate is greater than or equal to 3.2 μm and less than or equal to 10 μm.

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