A high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure and a preparation method thereof

Abstract

The present invention discloses a high-temperature oxidation-resistant, microwave-absorbing ceramic coating with a double-layer structure. The coating comprises, from the outside to the inside, a surface oxide layer and an inner layer. The surface oxide layer comprises Al2O3 and TiO2, while the inner layer comprises Al2O3, Ti2AlC, TiC, and TiO2. If the surface oxide layer detaches, the inner layer can be continuously oxidized to form the outer layer, thereby achieving sustainable microwave absorption and recyclability after long-term service in a high-temperature atmospheric environment. The preparation method comprises: milling Al2O3 and Ti2AlC in a planetary ball mill until thoroughly mixed to obtain a composite raw material powder. This composite raw material powder is then sprayed onto a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spray device to obtain a base coating. The base coating is then placed in a muffle furnace for high-temperature oxidation at a temperature of 800°C to 2000°C for a time of 0.1 to 10 hours, followed by cooling in the furnace. The double-layered, high-temperature oxidation-resistant, microwave-absorbing ceramic coating is finally obtained.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure and a preparation method thereof. Background Art

[0002] Since the 1990s, with the rapid development of aerospace technology and the development and application of near-space (20 km to 100 km) aircraft technology, hypersonic aircraft with speeds exceeding Mach 5 have become a key focus of development for aerospace and defense departments worldwide. Consequently, achieving stealth and penetration for hypersonic aircraft has become a hot research topic. Currently, applying radar-absorbing ceramic coatings to hypersonic aircraft surfaces is a key method for absorbing radar waves and achieving stealth. Regarding hypersonic aircraft structure, to prevent heat transfer to the rest of the vehicle, the transition between the warhead and the body is constructed of chromium-nickel-inconel alloy. The frame and cladding of the cruise missile, as well as the skin of the missile body and interstage, and the four fully movable tail fins, including the thrusters, are all constructed of aluminum. Titanium is used for some interstage structures and the thruster tail cone, while the thruster's outer surface is constructed of steel. At the same time, reusable hypersonic vehicles must also undergo high- and low-temperature transitions. This requires that the absorbing ceramic coating material applied to its surface must, on the one hand, have good interfacial bonding and thermal compatibility with the vehicle's metal substrate, and, on the other hand, be resistant to high-temperature oxidation, reusable, and maintain good absorbing properties even after long-term service in a high-temperature oxidizing environment. Therefore, developing and designing absorbing ceramic coatings that have good interfacial bonding with metal, are resistant to high-temperature oxidation, and are reusable is key to achieving stealth and long-term service.

[0003] Al2O3 composite microwave-absorbing ceramic coatings are currently being widely researched and applied. However, many traditional Al2O3 composite microwave-absorbing ceramic coatings have defects such as poor resistance to high-temperature oxidation and poor bonding strength between the coating and the substrate. Summary of the Invention

[0004] Based on the characteristic that Ti2AlC can be decomposed and oxidized to form TiO2 and Al2O3 in high-temperature air, the present invention creatively proposes to regulate the high-temperature oxidation process to treat the composite coating prepared with Ti2AlC and Al2O3 as raw materials. The invention successfully develops a high-temperature oxidation-resistant absorbing ceramic coating with a double-layer structure that has good absorbing performance, high-temperature oxidation resistance, good interface bonding with the metal substrate, and reusability, as well as a preparation method thereof.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a high-temperature oxidation-resistant, microwave-absorbing ceramic coating with a double-layer structure. The coating comprises a surface oxide layer and an inner layer. The surface oxide layer comprises 60-90 wt% Al2O3 and 10-40 wt% TiO2, while the inner layer comprises 60-90 wt% Al2O3, 1-10 wt% Ti2AlC, 5-20 wt% TiC, and 1-10 wt% TiO2. If the surface oxide layer falls off, the inner layer can continue to oxidize and transform into the outer layer, thus achieving sustainable microwave absorption and recyclable properties after long-term service in high-temperature atmospheric environments.

[0007] A further improvement of the present invention is that the thickness of the surface oxide layer is 0.1 to 1 mm, and the thickness of the inner layer is 1 to 2 mm.

[0008] A further improvement of the present invention is that the microhardness of the microwave-absorbing ceramic coating is 900-1100 HV, and the substrate-coating interface tensile bonding strength of the microwave-absorbing ceramic coating is 45-55 MPa.

[0009] A further improvement of the present invention is that, according to the GJB 2038-2011 standard - radar absorbing material RAM reflectivity bow method test standard, for a 180 mm × 180 mm × 1-3 mm sample of the absorbing ceramic coating, under test conditions using the radar absorbing material RAM reflectivity bow method within the X-band frequency range (8.2 GHz to 12.4 GHz), the effective absorbing bandwidth (reflection loss RL <-10 dB) of the absorbing ceramic coating is 1 to 4.2 GHz, and the minimum reflection loss is -10 to -60 dB.

[0010] The present invention also provides a method for preparing the high-temperature resistant oxidation absorbing ceramic coating having a double-layer structure, the method comprising the following steps:

[0011] Al2O3 and Ti2AlC are placed in a planetary ball mill and ball-milled until fully mixed to obtain a composite raw material powder, which is then sprayed on a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spraying device to obtain a base coating. Subsequently, the base coating is placed in a muffle furnace and subjected to a high-temperature oxidation treatment at an oxidation temperature of 800°C to 2000°C for an oxidation time of 0.1 to 10 hours. The base coating is finally cooled in the furnace to obtain the high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure.

[0012] Compared with the current existing technology, the present invention has the following characteristics:

[0013] The present invention creatively proposes to regulate the high-temperature oxidation process to treat a composite coating prepared with Ti2AlC and Al2O3 as raw materials, successfully preparing a high-temperature oxidation-resistant, wave-absorbing ceramic coating with a double-layer structure, which has excellent wave-absorbing properties. The coating includes a surface oxide layer and an inner layer from the outside to the inside. The surface oxide layer can prevent the wave-absorbing ceramic coating from further oxidation after long-term service in a high-temperature atmospheric environment. If the surface oxide layer falls off, the inner layer can be continuously oxidized and transformed into the outer layer, thereby achieving the effect of sustainable wave absorption and recycling, and extending the service life of the coating. In addition, the inner layer of the coating has a good interface with the metal substrate. The high-temperature oxidation treatment process described in the present invention is simple, easy to operate, and low-cost, making it suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a scanning electron microscope image of a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure according to Example 1 of the present invention;

[0015] Figure 2 A comparison chart of the measured reflection loss RL values ​​of the high-temperature resistant oxidation absorbing ceramic coating with a double-layer structure and the base coating according to Example 1 of the present invention;

[0016] Figure 3 This is a scanning electron microscope image of a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure according to Example 2 of the present invention;

[0017] Figure 4 This is a scanning electron microscope image of a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure according to Example 3 of the present invention; DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The elements and features described in one embodiment of the present invention may be combined with the elements and features shown in one or more other embodiments. It should be noted that for the purpose of clarity, the representation and description of components and processes that are not related to the present invention and are known to those of ordinary skill in the art are omitted in the description. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0019] The new ternary layered MAX phase ceramic is a good damage tolerance ceramic material with high strength and toughness as well as excellent metal-like electrical conductivity. Typical materials include Ti2AlC, Ti3AlC2 and Ti3SiC2, with a density of 4~5 g / cm 3, Young's modulus is 280~340 GPa, and room temperature fracture toughness is 6.0~7.88 MPa·m 1 / 2 . In addition, the new ternary MAX phase ceramic has the combined advantages of high-temperature self-healing repair, oxidation resistance, and good wetting and bonding with the metal substrate. Therefore, the new Al2O3 and Ti2AlC composite absorbing ceramic coating has become a new research direction. In order to achieve the overall goal of preparing an absorbing ceramic coating with good absorbing performance, high-temperature oxidation resistance, good interface bonding with the metal substrate, and reusability, the inventors creatively proposed to regulate the high-temperature oxidation process to treat the composite coating prepared with Ti2AlC and Al2O3 as raw materials, and successfully prepared a high-temperature oxidation-resistant absorbing ceramic coating with a double-layer structure, which has excellent absorbing performance. The coating includes a surface oxide layer and an inner layer from the outside to the inside. The surface oxide layer can prevent the absorbing ceramic coating from further oxidation after long-term service in a high-temperature atmospheric environment. If the surface oxide layer falls off, the inner layer can continue to oxidize and transform into the outer layer, thereby achieving the effect of sustainable absorption and recycling, and extending the service life of the coating. In addition, the inner layer of the coating has a good interface bonding with the metal substrate.

[0020] The present invention also provides a method for preparing the high-temperature resistant oxidation absorbing ceramic coating having a double-layer structure, the method comprising the following steps:

[0021] S1. Place Al2O3 and Ti2AlC in a planetary ball mill and ball-mill them until they are fully mixed to obtain a composite raw material powder, and spray the composite raw material powder on a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spraying device to obtain a base coating;

[0022] S2. Placing the base coating in a muffle furnace for high-temperature oxidation treatment at an oxidation temperature of 800°C to 2000°C for 0.1 to 10 hours, and finally cooling the base coating with the furnace to obtain the high-temperature oxidation-resistant microwave-absorbing ceramic coating with a double-layer structure.

[0023] The present invention is described in detail below with reference to specific embodiments. Example 1

[0024] Example 1 provides a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure and a preparation method thereof, the preparation method comprising:

[0025] Al2O3 and Ti2AlC are placed in a planetary ball mill and ball-milled until fully mixed to obtain a composite raw material powder, which is then sprayed onto a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spraying device to obtain a base coating; subsequently, the base coating is placed in a muffle furnace and subjected to a high-temperature oxidation treatment at 950°C for 2 hours, and finally cooled in the furnace to obtain the high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure. Figure 1 As shown in the figure, the thickness of the surface oxide layer of the coating is 0.1 mm. The main components of the surface oxide layer are TiO2 and Al2O3. The microhardness of the absorbing ceramic coating is 1000±50 HV, and the coating bonding strength is 50±5 MPa. Figure 2 As shown in the figure, compared with the basic coating, the reflection loss RL value of the absorbing ceramic coating is greatly reduced, proving that its absorbing performance is greatly improved. The effective absorbing bandwidth (reflection loss RL < -10 dB) is 1.6 GHz, and the minimum reflection loss is -11.2 dB. Example 2

[0026] Example 2 provides a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure and a preparation method thereof, the preparation method comprising:

[0027] Al2O3 and Ti2AlC are placed in a planetary ball mill and ball-milled until fully mixed to obtain a composite raw material powder, which is then sprayed onto a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spraying device to obtain a base coating; subsequently, the base coating is placed in a muffle furnace and subjected to a high-temperature oxidation treatment at a temperature of 1200°C for 5 hours, and finally cooled in the furnace to obtain the high-temperature oxidation-resistant wave-absorbing ceramic coating having a double-layer structure. Figure 3 As shown in the figure, the thickness of the surface oxide layer of the coating is 0.5 mm. The microhardness of the microwave-absorbing ceramic coating is 1050±50HV, and the coating bonding strength is 52±5 MPa. Example 3

[0028] Example 3 provides a high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure and a preparation method thereof, the preparation method comprising:

[0029] Al2O3 and Ti2AlC are placed in a planetary ball mill and ball-milled until fully mixed to obtain a composite raw material powder, which is then sprayed onto a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spraying device to obtain a base coating; subsequently, the base coating is placed in a muffle furnace and subjected to a high-temperature oxidation treatment at a temperature of 1500°C for 10 hours, and finally cooled in the furnace to obtain the high-temperature oxidation-resistant wave-absorbing ceramic coating having a double-layer structure. Figure 4As shown in the figure, the thickness of the surface oxide layer of the coating is 1.0 mm. The microhardness of the microwave-absorbing ceramic coating is 1100±50HV, and the coating bonding strength is 55±5 MPa.

[0030] In the above three embodiments, the Ti2AlC material used can be replaced by other MAX phase ceramics, such as Ti3AlC2, Ti3SiC2, etc.

[0031] The present invention creatively proposes to regulate the high-temperature oxidation process to treat a composite coating prepared with Ti2AlC and Al2O3 as raw materials, successfully preparing a high-temperature oxidation-resistant, wave-absorbing ceramic coating with a double-layer structure, which has excellent wave-absorbing properties. The coating includes a surface oxide layer and an inner layer from the outside to the inside. The surface oxide layer can prevent the wave-absorbing ceramic coating from further oxidation after long-term service in a high-temperature atmospheric environment. If the surface oxide layer falls off, the inner layer can be continuously oxidized and transformed into the outer layer, thereby achieving the effect of sustainable wave absorption and recycling, and extending the service life of the coating. In addition, the inner layer of the coating has a good interface with the metal substrate. The high-temperature oxidation treatment process described in the present invention is simple, easy to operate, and low-cost, making it suitable for large-scale industrial production.

[0032] Finally, it should be noted that although the present invention and its advantages have been described in detail above, it should be understood that various changes, substitutions, and modifications may be made without departing from the spirit and scope of the present invention as defined by the appended claims. Moreover, the scope of the present invention is not limited to the specific embodiments of the processes, devices, means, methods, and steps described in the specification. A person skilled in the art will readily understand from the disclosure herein that existing and future developed processes, devices, means, methods, or steps that perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein may be used in accordance with the present invention. Accordingly, the appended claims are intended to include within their scope such processes, devices, means, methods, or steps.

Claims

1. A high-temperature oxidation-resistant, wave-absorbing ceramic coating with a double-layer structure, comprising a surface oxide layer and an inner layer, the surface oxide layer comprising 60wt% to 90wt% Al2O3 and 10wt% to 40wt% TiO2, and the inner layer comprising 60wt% to 90wt% Al2O3, 1wt% to 10wt% Ti2AlC, 5wt% to 20wt% TiC, and 1wt% to 10wt% TiO2. If the surface oxide layer of the wave-absorbing ceramic coating falls off, the inner layer can be continuously oxidized to transform into the outer layer, thereby achieving the effect of sustainable wave absorption and recycling after long-term service in a high-temperature atmospheric environment.

2. The high-temperature oxidation-resistant microwave-absorbing ceramic coating with a double-layer structure according to claim 1, characterized in that: The surface oxide layer of the microwave-absorbing ceramic coating has a thickness of 0.1 to 1 mm, and the inner layer has a thickness of 1 to 2 mm.

3. The high-temperature oxidation-resistant microwave-absorbing ceramic coating with a double-layer structure according to claim 1, characterized in that: The microhardness of the wave-absorbing ceramic coating is 900-1100 HV, and the tensile bonding strength of the substrate-coating interface of the wave-absorbing ceramic coating is 45-55 MPa.

4. The high-temperature oxidation-resistant microwave-absorbing ceramic coating with a double-layer structure according to claim 1, characterized in that: Ti2AlC can be replaced by Ti3AlC2 or Ti3SiC2.

5. A method for preparing the high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure as claimed in claim 1, characterized in that: The method comprises the following steps: Step 1: Place Al2O3 and Ti2AlC in a planetary ball mill and ball mill them until they are fully mixed to obtain a composite raw material powder, and spray the composite raw material powder on a nickel-based alloy substrate or a carbon fiber substrate using a supersonic plasma spraying device to obtain a base coating; Step 2: placing the base coating described in step 1 in a muffle furnace for high-temperature oxidation treatment at an oxidation temperature of 800° C. to 2000° C. for 0.1 to 10 hours, and cooling with the furnace; Step 3: Finally, the high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure is obtained.

6. The method for preparing the high-temperature oxidation-resistant wave-absorbing ceramic coating with a double-layer structure according to claim 1 according to claim 5, characterized in that: The ball milling time is 8h to 12h.

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