A thermal barrier coating and metal substrate interface strengthening structure and method

Abstract

The application belongs to the field of ceramic matrix materials, and particularly relates to a reinforcing structure and method of the interface between a thermal barrier coating and a metal matrix. The reinforcing structure comprises a metal matrix and a thermal barrier coating; a reinforcing interface arranged in a rectangular net format is arranged on the connecting interface of the metal matrix, the reinforcing interface comprises a concave arc surface, the outer side of a single concave arc surface is in a rectangular structure, and two adjacent reinforcing interfaces share a side; the connecting interface of the thermal barrier coating conforms to the connecting interface of the metal matrix in morphology and is attached to each other. That is, the reinforcing structure of the interface between the thermal barrier coating and the metal matrix can strengthen the connecting strength of the thermal barrier coating and the metal matrix through structural improvement, can inhibit the growth of transverse cracks in a high-temperature state, and is suitable for metal matrices and thermal barrier coatings of various materials.

Description

Technical Field

[0001] The present invention belongs to the field of ceramic-based materials, and in particular relates to a structure and method for strengthening the interface between a thermal barrier coating and a metal substrate. Background Art

[0002] Thermal barrier coatings, primarily based on ceramic materials such as ZrO, AlO, and their rare earth dopants, are typically applied to metal substrates to provide thermal insulation. They are typically used in extremely high-temperature environments, such as aircraft engine flow path protection, where high-speed airflow erodes and creates extremely harsh environments.

[0003] Since the thermal expansion coefficient of ceramic materials is relatively low, generally 11 10 -6 / ℃, while the thermal expansion coefficient of metal matrix represented by stainless steel is generally 18 10 -6 The huge difference in thermal expansion coefficients leads to significant differences in the elongation of the structure under high temperature conditions. When the coating and substrate are tightly bonded, huge thermal stress will be induced. When the stress exceeds the bond strength limit, it will cause separation between the coating and the substrate, leading to serious failure phenomena such as cracks and peeling.

[0004] Traditional coating bonding reinforcement methods involve adding a metal-based bonding layer, such as NiCrAlY, between the ceramic layer and the metal substrate. This layer has a moderate thermal expansion coefficient, providing good thermal compatibility and strain resistance. This bonding layer ensures reliable adhesion of the ceramic-based thermal barrier coating to the metal substrate. However, under extremely high temperature conditions, the increased thickness of the thermal barrier coating creates significant temperature gradients between coating layers, leading to poor thermal compatibility within the coating, particularly at the interface.

[0005] The present invention proposes a method for strengthening the interface design between a thermal barrier coating and a metal substrate. By utilizing the internal compaction effect of the inner arc surface ceramic material under high temperature conditions, artificial control of the substrate surface morphology can be achieved. Without changing the thermal barrier coating and substrate material system and process methods, the coating performance of flat plates or inner hole parts can be improved, effectively solving the problem of weak bonding or even failure of the outer arc surface coating, achieving a significant improvement in the thermal shock resistance of the thermal barrier coating, and effectively improving the reusability of the thermal barrier coating. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a structure and method for strengthening the interface between a thermal barrier coating and a metal substrate.

[0007] The present invention provides a reinforcement structure for the interface between a thermal barrier coating and a metal substrate, comprising a metal substrate and a thermal barrier coating;

[0008] A strengthening interface arranged in a rectangular grid is provided on the connection interface of the metal substrate. The strengthening interface includes a concave arc surface. The outer side of a single concave arc surface is a rectangular structure, and two adjacent strengthening interfaces share a common edge.

[0009] The connection interface of the thermal barrier coating and the connection interface of the metal substrate are consistent in morphology and fit together.

[0010] Furthermore, the outer side of the single concave arc surface is a square structure.

[0011] Furthermore, the radius of the concave surface is 7 to 70 times the thickness of the thermal barrier coating.

[0012] Furthermore, the length of the outer side is 2.5 times to 3.5 times the thickness of the thermal barrier coating, and the length of the outer side is smaller than the radius of the concave arc surface.

[0013] Furthermore, the radius of the concave arc surface is 4 to 10 times the length of the outer side.

[0014] Furthermore, the thermal barrier coating includes a ceramic layer and a bonding layer.

[0015] Furthermore, the ceramic layer is zirconium oxide, aluminum oxide or tantalate.

[0016] Furthermore, the metal matrix is ​​stainless steel, high temperature alloy or refractory metal.

[0017] Furthermore, the thermal barrier coating is prepared by plasma spraying; and the metal substrate is prepared by 3D printing.

[0018] The present invention also provides a method for strengthening the interface between a thermal barrier coating and a metal substrate, using the above-mentioned strengthening structure for the interface between the thermal barrier coating and the metal substrate;

[0019] After the metal substrate and thermal barrier coating are combined, while maintaining the performance of the original thermal barrier coating, the following are achieved:

[0020] The combination of thermal barrier coating and concave arc surface decomposes the shear stress generated at the interface of the metal substrate and thermal barrier coating due to the difference in expansion coefficient between the two, decomposing it into the force component perpendicular to the interface and the force component along the interface, thereby greatly reducing the shear stress in the parallel direction and inhibiting the growth of transverse cracks.

[0021] The combination of thermal barrier coating and concave arc surface increases the interface area between the metal substrate and thermal barrier coating, improves the overall stress-bearing area, increases the strain tolerance of thermal barrier coating, and inhibits the growth of transverse cracks.

[0022] The outer edges of adjacent concave arc surfaces form a peak structure, which suppresses the stress and crack propagation caused by thermal strain.

[0023] The beneficial effects of the present invention are that the reinforcement structure of the interface between the thermal barrier coating and the metal substrate provided by the present invention can, after the metal substrate and the thermal barrier coating are combined, enhance the combined strength of the metal substrate and the thermal barrier coating in the following aspects while maintaining the performance of the original thermal barrier coating:

[0024] On the one hand, the combination of the thermal barrier coating and the concave surface decomposes the shear stress generated at the interface between the metal substrate and the thermal barrier coating due to the difference in expansion coefficient between the two, decomposing it into a force component perpendicular to the interface and a force component along the interface, thereby greatly reducing the shear stress in the parallel direction and inhibiting the growth of transverse cracks.

[0025] Thermal barrier coatings adhere to metal substrates, initially experiencing no stress or strain at room temperature. However, as the temperature of the structure rises, differences in expansion coefficients generate significant shear stress at the interface. This shear stress is the primary cause of transverse crack growth and thermal barrier coating shedding. In this embodiment, the concave surface significantly reduces shear stress, inhibiting transverse crack growth and minimizing the likelihood of thermal barrier coating shedding.

[0026] In addition, since the thermal barrier coating has a high bonding strength and can effectively resist strain in the vertical direction, the adverse effect of the vertical interface force decomposed by the concave surface on the thermal barrier coating can be ignored.

[0027] On the other hand, the combination of the thermal barrier coating and the concave arc surface increases the area of ​​the interface between the metal substrate and the thermal barrier coating, thereby increasing the overall stress-bearing area. This means that the same force or deformation can be shared by a larger area of ​​the interface, improving the strain tolerance of the thermal barrier coating and inhibiting the growth of transverse cracks.

[0028] On the other hand, the outer sides of adjacent concave arc surfaces form a peak structure, which suppresses the stress and crack propagation caused by thermal strain.

[0029] Specifically, the spike structure can effectively block or deflect the expansion of tiny cracks formed at the interface in the parallel direction, preventing the cracks from penetrating the entire interface and improving the service life. It can also inhibit the propagation of stress caused by thermal strain.

[0030] The reinforced structure at the interface between the thermal barrier coating and the metal substrate of the present invention enhances the bond strength between the thermal barrier coating and the metal substrate through structural improvements alone, inhibiting transverse crack growth at high temperatures. This makes it suitable for metal substrates and thermal barrier coatings of various materials. Experiments have shown that the present invention can significantly improve thermal shock resistance with minimal weight gain in the metal substrate. When using a concave arc radius seven times the thickness of the thermal barrier coating and an outer edge length five times that of the coating, a three-fold improvement in thermal shock resistance can be achieved. When using a concave arc radius 33 times the thickness of the thermal barrier coating, a still-doubled thermal shock resistance can be achieved, with only a 2.21% weight gain in the metal substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attachment Figure 1 Schematic diagram of the peeling of a flat thermal barrier coating in the prior art;

[0032] Attachment Figure 2 Schematic diagram of the shedding of the thermal barrier coating with a strengthened interface according to the present invention;

[0033] Attachment Figure 3 It is a front view of the metal matrix with a strengthened interface in the present invention;

[0034] Attachment Figure 4 Schematic diagram of the structure of the metal matrix with a strengthened interface in the present invention;

[0035] Attachment Figure 5 This is a morphology diagram of the test block before testing of the present invention;

[0036] Attachment Figure 6 This is a morphology diagram of the test block after testing according to the present invention.

[0037] In the figure, 1-metal substrate; 11-reinforced interface; 111-concave arc surface; 112-outer edge; 2-thermal barrier coating. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0040] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0041] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean mechanical connection, electrical connection, physical connection, or wireless communication connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] As attached Figure 1 -Attached Figure 4 As shown, the present invention provides a reinforcement structure of the interface between a thermal barrier coating and a metal substrate, comprising a metal substrate 1 and a thermal barrier coating 2; wherein, the thermal barrier coating 2 is arranged on the connection interface of the metal substrate 1, and the side where the thermal barrier coating 2 is connected to the metal substrate 1 is the connection interface of the thermal barrier coating 2.

[0044] A strengthening interface 11 arranged in a rectangular grid is provided on the connection interface of the metal substrate 1, that is, the strengthening interface 11 is arranged in a rectangular grid and covers the entire connection interface of the metal substrate 1, and the strengthening interfaces 11 are closely attached to each other and arranged in a rectangular array. The strengthening interface 11 includes a concave arc surface 111, and the concave arc surface 111 is a spherical cap structure. The outer side 112 of a single concave arc surface 111 is a rectangular structure. Specifically, the outer side 112 of a single concave arc surface 111 is rectangular when viewed from above, and each side is an arc structure. Two adjacent strengthening interfaces 11 share a common edge. Since the outer side 112 is the high point of the concave arc surface 111, the common edge position of the two strengthening interfaces 11 will form a peak structure.

[0045] The interface of the thermal barrier coating 2 is co-morphologically aligned with the interface of the metal substrate 1. The metal substrate 1 and the thermal barrier coating 2 can be connected in various ways, such as by directly forming the two into a single piece (3D printing), bonding them together, or machining the thermal barrier coating 2 onto the metal substrate 1 (spraying).

[0046] The reinforced structure of the interface between the thermal barrier coating and the metal substrate provided by the present invention can, after the metal substrate 1 and the thermal barrier coating 2 are combined, enhance the combined strength of the metal substrate 1 and the thermal barrier coating 2 in the following aspects while maintaining the original performance of the thermal barrier coating 2:

[0047] On the one hand, the combination of the thermal barrier coating 2 and the concave arc surface 111 decomposes the shear stress generated at the interface between the metal substrate 1 and the thermal barrier coating 2 due to the difference in expansion coefficient between the two, into a force component perpendicular to the interface and a force component along the interface, thereby greatly reducing the shear stress in the parallel direction and inhibiting the growth of transverse cracks.

[0048] The thermal barrier coating 2 adheres to the metal substrate 1 and, in its initial state at room temperature, is free of stress and strain. However, as the temperature of the structure rises, differences in expansion coefficients generate significant shear stress at the interface. This shear stress is the primary cause of transverse crack growth and subsequent shedding of the thermal barrier coating 2. In this embodiment, the provision of the concave curved surface 111 significantly reduces shear stress, thereby inhibiting transverse crack growth and reducing the likelihood of shedding of the thermal barrier coating 2.

[0049] In addition, since the thermal barrier coating 2 has a high bonding strength and can effectively resist strain in the vertical direction, the adverse effect of the vertical interface force component decomposed by the concave arc surface 111 on the thermal barrier coating 2 can be ignored.

[0050] On the other hand, the combination of the thermal barrier coating 2 and the concave arc surface 111 increases the area of ​​the connection interface between the metal substrate 1 and the thermal barrier coating 2, thereby increasing the overall force-bearing area. This means that the same force or deformation can be shared by a larger area of ​​the interface, thereby increasing the strain tolerance of the thermal barrier coating 2 and inhibiting the growth of transverse cracks.

[0051] On the other hand, the outer edges 112 of adjacent concave arc surfaces 111 form a peak structure, which suppresses the stress and crack propagation caused by thermal strain.

[0052] Specifically, the spike structure can effectively block or deflect the expansion of tiny cracks formed at the interface in the parallel direction, preventing the cracks from penetrating the entire interface and improving the service life. It can also inhibit the propagation of stress caused by thermal strain.

[0053] The reinforced structure at the interface between the thermal barrier coating and the metal substrate of the present invention enhances the bond strength between the thermal barrier coating and the metal substrate through structural improvements alone, inhibiting transverse crack growth at high temperatures. This makes it suitable for metal substrates and thermal barrier coatings of various materials. Experiments have shown that the present invention can significantly improve thermal shock resistance with minimal weight increase in the metal substrate 1. When using a concave surface 111 radius seven times the thickness of the thermal barrier coating 2 and an outer edge 112 length five times that of the outer edge 112, a three-fold improvement in thermal shock resistance can be achieved. When the thickness of the thermal barrier coating 2 is 33 times the radius of the concave surface 111, a still-doubled thermal shock resistance is achieved, with only a 2.21% weight increase in the metal substrate 1.

[0054] In one embodiment, the outer side 112 of the single concave arc surface 111 is in a square structure. This arrangement can ensure that the reinforcement effect in the horizontal and vertical directions is consistent.

[0055] In one embodiment, the radius of the concave arc surface 111 is 7 to 70 times the thickness of the thermal barrier coating 2. In this way, the enhancement effect, reusability and acceptable weight gain can be ensured.

[0056] In one embodiment, the length of outer edge 112 is 2.5 to 3.5 times the thickness of thermal barrier coating 2. Preferably, the length of outer edge 112 is 3 times the thickness of thermal barrier coating 2. The length of outer edge 112 is also less than the radius of concave arc surface 111. In this embodiment, the length of outer edge 112 is determined based on the curvature of concave arc surface 111 and the acceptable weight gain effect of strengthening interface 11.

[0057] In one embodiment, the radius of the concave surface 111 is 4 to 10 times the length of the outer side 112. Calculations show that when the radius r of the concave surface 111 is greater than 4 times the length of the outer side 112, the weight gain of the metal substrate 1 is significantly reduced and tends to be stable.

[0058] In one embodiment, the thermal barrier coating 2 includes a ceramic layer and a bonding layer.

[0059] For example, the ceramic layer is zirconium oxide, aluminum oxide, or tantalate. The ceramic layer can also be other types of coating materials.

[0060] For example, the metal substrate 1 is made of stainless steel, high-temperature alloy or refractory metal. The metal substrate 1 may also be made of other types of metal structural materials.

[0061] In one embodiment, the thermal barrier coating 2 is prepared by plasma spraying, and the metal substrate 1 is prepared by 3D printing, so as to facilitate production.

[0062] The present invention also provides a method for strengthening the interface between a thermal barrier coating and a metal substrate, using the above-mentioned strengthening structure for the interface between the thermal barrier coating and the metal substrate;

[0063] After the metal substrate 1 and the thermal barrier coating 2 are combined, while maintaining the original performance of the thermal barrier coating 2, the following steps are performed:

[0064] The combination of the thermal barrier coating 2 and the concave arc surface 111 decomposes the shear stress generated at the interface between the metal substrate 1 and the thermal barrier coating 2 due to the difference in expansion coefficient between the two, into a force component perpendicular to the interface and a force component along the interface, thereby greatly reducing the shear stress in the parallel direction and inhibiting the growth of transverse cracks.

[0065] The thermal barrier coating 2 is combined with the concave arc surface 111, the area of the connecting interface between the metal base 1 and the thermal barrier coating 2 is increased, the overall stress area is increased, the strain tolerance of the thermal barrier coating 2 is improved, and the growth of transverse cracks is inhibited.

[0066] The outer side edge 112 of the adjacent concave arc surface 111 forms a sharp peak structure, and the stress and crack propagation caused by thermal strain are inhibited.

[0067] The application also provides a size determination method of the reinforced interface, and reference is made to the accompanying drawings Figure 3 , wherein r is the radius of the concave arc surface, alpha is the semi-arc angle, h1 is the thickness of the thin point of the metal base, h2 is the thickness of the thick point of the metal base, and the height difference of the reinforced interface , .

[0068] The size determination method comprises:

[0069] The radius r of the concave arc surface 111:

[0070] The radius r of the concave arc surface 111 of the reinforced interface 11 is mainly determined according to the thickness of the thermal barrier coating 2. The radius r of the concave arc surface 111 is one of the main influencing parameters of the height difference of the reinforced interface 11 and the volume change of the metal base 1, and needs to be considered according to the expected performance increase of repeated use and the acceptable weight increase balance. The total thickness of the ceramic layer and the bonding layer of the thermal barrier coating 2 is l , and the value range of the radius r of the concave arc surface 111 is generally 7 l ~70 l .

[0071] The side length d of the outer side edge 112:

[0072] Since the concave arc surface 111 is a spherical cap structure, and the outer side edge 112 is a square, the four side lengths of the outer side edge 112 are all d. According to the arc of the concave arc surface 111 and the acceptable weight increase influence caused by the height difference of the reinforced interface, the value range is generally d >3 l and d < r .

[0073] The weight increase of the metal base 1:

[0074] The weight increase of the metal base 1 is calculated and obtained through the following process:

[0075] The semi-arc angle alpha:

[0076] ;

[0077] The height difference of the reinforced interface:

[0078] ;

[0079] Volume increment of a single strengthening interface 11:

[0080] ;

[0081] The weight gain calculation formula for a single metal substrate 1 is:

[0082] ;

[0083] in, ρ is the density of the metal matrix material.

[0084] According to the above-mentioned method for determining the size of the strengthening interface, four test blocks were determined, in which the overall side length was 21.6 mm and the metal substrate 1 was a stainless steel test block with a thickness of 3.7 mm. The side length d of the single strengthening interface 11 was 7.2 mm. The radius r of the concave arc surface 111 of the four test blocks was 0 mm, 10 mm, 30 mm, and 50 mm respectively. Among them, r = 0 is the flat coating control group. Taking the test block with r = 10 mm as an example, the model is as follows Figure 4 shown.

[0085] Conventional plasma spraying is used on the connection interface of the metal substrate 1 to obtain a thickness of l =1.5mm yttrium stabilized zirconia thermal barrier coating: before testing, the test piece is as follows Figure 5 shown.

[0086] After the four test blocks were kept in a muffle furnace at 1200℃ for 10 minutes, they were quickly put into water. The number of thermal shocks required for each test block to fall off was tested. The morphology of the test blocks after the test was as follows: Figure 6 As shown, the red numbers are the number of thermal shock tests.

[0087] According to statistics, the test results are as follows:

[0088]

[0089] Tests have shown that the present invention significantly improves thermal shock resistance with minimal weight increase in the metal substrate. Using a radius seven times the coating thickness and a grid length five times the coating thickness yields a threefold improvement in thermal shock resistance. Increasing the radius to 33 times the coating thickness still achieves a twofold improvement in thermal shock resistance, while increasing the weight of the metal substrate by only approximately 2.21%.

[0090] The increase in weight of the metal substrate 1 is mainly dominated by the length of the outer edge 112 and the radius r of the concave arc surface 111. Calculation results show that when the radius r of the concave arc surface 111 is greater than 4 times the length of the outer edge 112, the weight gain of the metal substrate 1 is greatly reduced and tends to be stable. Therefore, the value range of the radius r of the concave arc surface 111 is 4d-10d.

[0091] The above description is merely an embodiment and does not limit the present invention in any way. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes, modifications, or modifications to the technical solution of the present invention into equivalent embodiments with equivalent changes using the technical content disclosed above. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A strengthening structure of the interface between a thermal barrier coating and a metal substrate, characterized in that: It includes a metal substrate (1) and a thermal barrier coating (2); A strengthening interface (11) arranged in a rectangular grid is provided on the connection interface of the metal substrate (1), the strengthening interface (11) including a concave arc surface (111), the outer side (112) of a single concave arc surface (111) is rectangular in a top view, and each side is an arc structure, and two adjacent strengthening interfaces (11) share a common edge; The connection interface of the thermal barrier coating (2) and the connection interface of the metal substrate (1) are co-morphological and conform to each other.

2. The strengthening structure of the interface between the thermal barrier coating and the metal substrate according to claim 1, characterized in that: The outer side (112) of the single concave arc surface (111) is in a square structure.

3. The strengthening structure of the interface between the thermal barrier coating and the metal substrate according to claim 1, characterized in that: The radius of the concave arc surface (111) is 7 to 70 times the thickness of the thermal barrier coating (2).

4. The strengthening structure of the interface between the thermal barrier coating and the metal substrate according to claim 1, characterized in that: The side length of the outer edge (112) is 2.5 to 3.5 times the thickness of the thermal barrier coating (2), and the side length of the outer edge (112) is smaller than the radius of the concave arc surface (111).

5. The strengthening structure of the interface between the thermal barrier coating and the metal substrate according to claim 1, wherein: The radius of the concave arc surface (111) is 4 to 10 times the length of the outer side (112).

6. The reinforcement structure of the interface between the thermal barrier coating and the metal substrate according to any one of claims 1 to 4, characterized in that: The thermal barrier coating (2) includes a ceramic layer and a bonding layer.

7. The strengthening structure of the interface between the thermal barrier coating and the metal substrate according to claim 5, characterized in that: The ceramic layer is zirconium oxide, aluminum oxide or tantalate.

8. The reinforcement structure of the interface between the thermal barrier coating and the metal substrate according to any one of claims 1 to 4, characterized in that: The metal substrate (1) is stainless steel, high temperature alloy or refractory metal.

9. The reinforcement structure of the interface between the thermal barrier coating and the metal substrate according to any one of claims 1 to 4, characterized in that: The thermal barrier coating (2) is prepared by plasma spraying; and the metal substrate (1) is prepared by 3D printing.

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