Silicon oxide nanowire-reinforced atomic oxygen protection coating and method of making same

Abstract

The application provides a silicon oxide nanowire reinforced atomic oxygen protection coating and a preparation method thereof, and relates to the technical field of space environment material protection. The coating has a three-layer composite structure: a substrate surface is provided with an inner layer of an ultra-thin polysiloxane layer, which serves as an interface transition layer; silicon oxide nanowires are grown on the surface of the inner layer of the polysiloxane layer and form a network, which provides a three-dimensional stress dispersion path and can prevent delamination and crack propagation; and an outer layer of a thick polysiloxane layer is deposited on the surface of the silicon oxide nanowire layer, which can provide penetration resistance. The application introduces a silicon oxide nanowire structure, which plays a role of a mechanical buffer framework, disperses local stress caused by atomic oxygen erosion, inhibits crack propagation in the plane direction, and significantly improves the anti-fracture performance. The silicon oxide nanowires are directly combined with the polysiloxane through silicon-oxygen covalent bonds (Si-O-Si), which enhances the synergy of the layers and realizes the synergistic oxygen resistance ability.

Description

Technical Field

[0001] This invention relates to the field of space environment material protection technology, specifically to a silicon oxide nanowire-reinforced atomic oxygen protective coating and its preparation method. Background Technology

[0002] In low Earth orbit (LEO), atomic oxygen (AO, average energy 0.5-10 eV) reacts violently with spacecraft surfaces, leading to gradual erosion, damage, or performance degradation of materials. Polysiloxane atomic oxygen protective coatings are currently one of the commonly used protective materials. However, due to long-term exposure to the high-flux atomic oxygen environment in LEO, factors such as cross-linking chain breakage, surface oxidation, and volume shrinkage cause polysiloxane atomic oxygen protective coatings to crack and even peel off. Although thickening or modifying the polymer can partially alleviate these problems, it cannot solve the fundamental structural defects.

[0003] Studies have shown that mechanical stress concentration is the main cause of cracking in atomic oxygen protective coatings, especially in weak areas at the layer interface, where crack initiation and propagation are more likely to occur. Therefore, it is necessary to improve the fracture resistance of atomic oxygen protective coatings through microstructure design.

[0004] Therefore, developing a polysiloxane protective coating that is not prone to cracking failure under atomic oxygen bombardment and high and low temperature thermal stress has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the fact that polysiloxane atomic oxygen protective coatings are prone to cracking or even peeling when exposed to the high-flux atomic oxygen environment in low Earth orbit for a long time. The present invention provides a silicon oxide nanowire-reinforced atomic oxygen protective coating and its preparation method. By introducing a silicon oxide (SiOx) nanowire structure, under the action of atomic oxygen bombardment and high and low temperature thermal stress, the crack initiation of the atomic oxygen protective coating caused by stress concentration is suppressed.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an atomic oxygen protective coating reinforced with silicon oxide nanowires, comprising a first polysiloxane layer, a silicon oxide nanowire layer and a second polysiloxane layer, wherein the first polysiloxane layer is deposited on the surface of a substrate, the silicon oxide nanowire layer is deposited on the surface of the first polysiloxane layer, and the second polysiloxane layer is deposited on the surface of the silicon oxide nanowire layer.

[0007] Furthermore, the silicon oxide nanowire layer includes SiOx nanowires, which are vertically aligned.

[0008] Furthermore, the SiOx nanowires have an average diameter of 5-30 nm, a length of 100-300 nm, and a porosity of 50%-70% (by volume).

[0009] Furthermore, the thickness of the first polysiloxane layer is 5~100 nm.

[0010] Furthermore, the thickness of the second polysiloxane layer is 300~500 nm.

[0011] Secondly, the present invention provides a method for preparing the silicon oxide nanowire-reinforced atomic oxygen protective coating, comprising preparing it by plasma-enhanced chemical vapor deposition (PECVD).

[0012] Furthermore, the method for preparing the silicon oxide nanowire-reinforced atomic oxygen protective coating includes the following steps: (1) A first polysiloxane layer is vacuum deposited on the substrate surface; (2) Silicon oxide nanowires are oriented and grown on the surface of the first polysiloxane layer by vacuum pulsed plasma deposition to form a silicon oxide nanowire layer; (3) A second polysiloxane layer is formed on the surface of the silicon oxide nanowire layer by self-biased deposition.

[0013] Further, in step (1), the conditions for vacuum deposition are: the precursor is a mixture of hexamethyldisiloxane (HMDSO) and oxygen, the power is 100~500 W, and the temperature is 50~150℃.

[0014] Further, in step (2), the conditions for vacuum pulsed plasma deposition are: the precursor is a mixture of tetraethoxysilane (TEOS) and oxygen, gold nanoparticles are used as catalyst, the pulse width is 10~100 ms, and the pulse period is 50~500 ms.

[0015] Furthermore, in step (3), the conditions for the self-biased deposition are: using silicon nitride as a modified crosslinking agent to embed it into the gaps between the silicon oxide nanowires to form a mechanical locking structure.

[0016] The technical solution of this invention has the following advantages: 1. This invention provides a three-layer composite atomic oxygen protective coating. An inner ultrathin polysiloxane layer is deposited on the substrate surface as an interface transition layer. Silica nanowires are oriented and grown on the surface of the inner polysiloxane layer, forming a network that provides a three-dimensional stress dispersion path. This stress dispersion prevents delamination and crack propagation. An outer thick polysiloxane layer is deposited on the surface of the silica nanowire layer to provide penetration resistance.

[0017] 2. This invention introduces a silicon oxide nanowire structure, which acts as a "mechanical buffer framework," dispersing localized stress caused by atomic oxygen erosion, inhibiting crack propagation along the planar direction, and significantly improving fracture resistance. The silicon oxide nanowires and polysiloxane are directly bonded through silicon-oxygen covalent bonds (Si-O-Si), enhancing the synergy of each layer and achieving synergistic antioxidant capacity.

[0018] 3. The present invention utilizes the gradient thickness between the inner polysiloxane layer and the outer thick polysiloxane layer to alleviate the accumulation of residual stress under thermal cycling.

[0019] 4. Plasma-enhanced chemical vapor deposition (PECVD) is used for preparation, a simple and controllable method. Silicon nitride is used as a crosslinking agent, embedded in the gaps between silicon oxide nanowires to form a mechanically interlocking structure, thereby enhancing three-dimensional adhesion. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the silicon oxide nanowire-reinforced atomic oxygen protective coating provided in an embodiment of the present invention; in the figure, 1-Base, 2-First polysiloxane layer, 3-Silica nanowire layer, 4-Second polysiloxane top layer. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0023] Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. All raw materials or instruments used are commercially available conventional products, including but not limited to those used in the embodiments of this application.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The following will, in conjunction with the accompanying drawings, provide a detailed description of a silicon oxide nanowire-reinforced atomic oxygen protective coating and its preparation method, based on embodiments of this application.

[0025] Please see Figure 1 This document provides a schematic diagram of a silicon oxide nanowire-reinforced atomic oxygen protective coating, as described in this application embodiment. To suppress cracking failure of the polysiloxane protective coating under atomic oxygen bombardment and high / low temperature thermal stress, and to avoid mechanical stress concentration leading to cracking of the atomic oxygen protective coating, crack initiation and propagation are induced in the weak areas of the layer interface. This microstructural design improves the fracture resistance of the atomic oxygen protective coating. Figure 1 As shown, this application provides a silicon oxide nanowire-reinforced atomic oxygen protective coating with a three-layer composite structure, including: a first polysiloxane layer 2, a silicon oxide nanowire layer 3, and a second polysiloxane layer 4.

[0026] The first polysiloxane layer 2 is deposited on the surface of the substrate 1, serving as a substrate buffer layer and interface transition layer, with a thickness of 50~100 nm.

[0027] A silica nanowire layer 3 is oriented and grown on the surface of the first polysiloxane layer 2. The silica nanowire layer comprises SiOx nanowires. The SiOx nanowires have a vertically villous structure, arranged vertically to form a network, providing a three-dimensional stress dispersion path. This stress dispersion prevents delamination and crack propagation. A thick outer polysiloxane layer is deposited on the surface of the silica nanowire layer to provide penetration resistance. The SiOx nanowires have an average diameter of 5–30 nm, a length of 100–300 nm, and a porosity of 50%–70% (by volume).

[0028] The second polysiloxane layer 4 is deposited on the surface of the silicon oxide nanowire layer 3, with a thickness of 300~500 nm, and provides anti-penetration capability.

[0029] By introducing SiOx nanowire structures, a "mechanical buffer framework" is formed, dispersing the localized stress caused by atomic oxygen erosion, inhibiting crack propagation along the planar direction, and significantly improving fracture resistance. The SiOx nanowires have a vertical villous structure, arranged vertically to form a network, providing a three-dimensional stress dispersion path. Through stress dispersion, delamination and crack propagation can be prevented.

[0030] A gradient thickness is formed between the first polysiloxane layer 2 and the second polysiloxane layer 4 to alleviate the accumulation of residual stress under thermal cycling.

[0031] SiOx nanowires and polysiloxanes are directly bonded through silicon-oxygen covalent bonds (Si-O-Si), enhancing the synergy of each layer and achieving synergistic antioxidant capacity.

[0032] The silicon oxide nanowire-reinforced atomic oxygen protective coating provided in this embodiment of the invention is prepared by plasma-enhanced chemical vapor deposition (PECVD). Silicon nitride is used as a crosslinking agent, embedded in the gaps between SiOx nanowires to form a mechanically interlocking structure, thereby enhancing three-dimensional adhesion.

[0033] In a preferred embodiment of the present invention, the method for preparing a silicon oxide nanowire-reinforced atomic oxygen protective coating includes the following steps: (1) A first polysiloxane layer 2 is vacuum deposited on the surface of substrate 1, using a mixture of hexamethyldisiloxane (HMDSO) and oxygen as a precursor, with a power of 300 W and a temperature of 100℃. (2) Silica nanowires are oriented and grown on the surface of the first polysiloxane layer 2 by vacuum pulsed plasma deposition to form silica nanowire layer 3. The precursor is a mixture of tetraethoxysilane (TEOS) and oxygen. Gold nanoparticles are used as catalysts. The pulse width is 10 ms / cycle 5s and the pulse period is 50 ms. (3) A second polysiloxane layer 4 is formed on the surface of the silicon oxide nanowire layer 3 by self-biased deposition. Silicon nitride is used as a modified crosslinking agent to embed it into the gaps between the silicon oxide nanowires to form a mechanical locking structure.

[0034] The preferred embodiment of the silicon oxide nanowire-reinforced atomic oxygen protective coating has the following characteristics: the thickness of the first polysiloxane layer 2 is 80 nm; the SiOx nanowires of the silicon oxide nanowire layer 3 have a diameter of 20 nm, a length of 300 nm, and a porosity of 60% (by volume); and the thickness of the second polysiloxane layer 4 is 400 nm.

[0035] Test case Using a polysiloxane atomic oxygen protective coating without silica nanowires as a control, the crack resistance and durability of the silica nanowire-reinforced atomic oxygen protective coating prepared in the embodiments of the present invention were tested.

[0036] The example coating and the control (single-layer polysiloxane) coating were prepared on the polyimide substrate, and the crack resistance and durability were tested.

[0037] Crack resistance test Crack resistance test method: The test specimens and control specimens of the examples were fixed on a bending fixture, subjected to a constant tensile strain of 0.5%, and then placed in an atomic oxygen ground simulation device; the atomic oxygen flux was 1×10⁻⁶. 16 Exposure was carried out under conditions of atoms / (cm²·s); for every 5.0 × 10⁻⁶ atoms / (cm²·s) of cumulative exposure. 19After reaching atoms / cm², the experiment was interrupted, and surface cracks were observed and counted using a field emission scanning electron microscope. When a continuous through-crack with a length ≥5 μm appeared on the sample surface, it was determined to be a failure. The cumulative atomic oxygen flux at the failure of the test sample and the control sample in the example was recorded, and the performance improvement factor was calculated.

[0038] Crack resistance test results: Compared with the control coating (single-layer polysiloxane), the silicon oxide nanowire-reinforced atomic oxygen protective coating prepared in this embodiment of the invention has improved crack resistance by 2-3 orders of magnitude; the control coating failed when the critical crack length was 5 μm.

[0039] Durability test Durability testing methods: Ground-based accelerated aging tests were used to evaluate coating durability. Coating samples were placed in a comprehensive space environment simulation facility, and the following tests were performed sequentially: atomic oxygen exposure flux of 1×10⁻⁶. 16 atoms / (cm²·s), for 100 h; surface morphology was observed by scanning electron microscopy, and mass loss and crack density were measured.

[0040] Durability test results: Compared with the control coating (single-layer polysiloxane), the surface damage area of ​​the silicon oxide nanowire-reinforced atomic oxygen protective coating prepared in the embodiments of the present invention is reduced by 95%, and the peeling rate is reduced from 45% to <3%.

[0041] In summary, this invention employs plasma-enhanced chemical vapor deposition (PECVD) to prepare a three-layer composite atomic oxygen protective coating on a substrate surface. The inner ultrathin polysiloxane layer serves as an interface transition layer. Silica nanowires are oriented and grown on the surface of the inner polysiloxane layer, forming a network that provides a three-dimensional stress dispersion path. This stress dispersion prevents delamination and crack propagation. An outer thick polysiloxane layer is deposited on the surface of the silica nanowire layer, providing penetration resistance. The introduction of the silica nanowire structure acts as a "mechanical buffer skeleton," dispersing localized stress caused by atomic oxygen erosion, inhibiting crack propagation along the planar direction, and significantly improving fracture resistance. The silica nanowires and polysiloxane are directly bonded through silicon-oxygen covalent bonds (Si-O-Si), enhancing the synergy of each layer and achieving synergistic oxygen resistance. The gradient thickness between the inner polysiloxane layer and the outer thick polysiloxane layer alleviates the accumulation of residual stress under thermal cycling. Therefore, the silicon oxide nanowire-reinforced atomic oxygen protective coating provided by this invention is not prone to cracking, peeling, or failure when exposed to a high-flux atomic oxygen environment in low Earth orbit for a long period of time.

[0042] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A silicon oxide nanowire-reinforced atomic oxygen protective coating, characterized in that, It includes a first polysiloxane layer, a silicon oxide nanowire layer, and a second polysiloxane layer, wherein, The first polysiloxane layer is deposited on the substrate surface, the silicon oxide nanowire layer is deposited on the surface of the first polysiloxane layer, and the second polysiloxane layer is deposited on the surface of the silicon oxide nanowire layer.

2. The silicon oxide nanowire-reinforced atomic oxygen protective coating according to claim 1, characterized in that, The silicon oxide nanowire layer includes SiOx nanowires, which are vertically arranged and have an average diameter of 5-30 nm, a length of 100-300 nm, and a porosity of 50%-70% (by volume).

3. The silicon oxide nanowire-reinforced atomic oxygen protective coating according to claim 1, characterized in that, The thickness of the first polysiloxane layer is 5~100 nm, and the thickness of the second polysiloxane layer is 300~500 nm.

4. The method for preparing the silicon oxide nanowire-reinforced atomic oxygen protective coating according to any one of claims 1 to 3, characterized in that, It was prepared by plasma-enhanced chemical vapor deposition (PECVD).

5. The preparation method according to claim 4, characterized in that, Includes the following steps: (1) A first polysiloxane layer is vacuum deposited on the substrate surface; (2) Silicon oxide nanowires are oriented and grown on the surface of the first polysiloxane layer by vacuum pulsed plasma deposition to form a silicon oxide nanowire layer; (3) A second polysiloxane layer is formed on the surface of the silicon oxide nanowire layer by self-biased deposition.

6. The preparation method according to claim 5, characterized in that, In step (1), the vacuum deposition conditions are: the precursor is a mixture of hexamethyldisiloxane (HMDSO) and oxygen, the power is 100~500 W, and the temperature is 50~150℃.

7. The preparation method according to claim 5, characterized in that, In step (2), the conditions for vacuum pulsed plasma deposition are: the precursor is a mixture of tetraethoxysilane (TEOS) and oxygen, gold nanoparticles are used as catalyst, the pulse width is 10~100 ms, and the pulse period is 50~500 ms.

8. The method for preparing the lunar dust adhesion film according to claim 6, characterized in that, In step (3), the conditions for self-biased deposition are: silicon nitride is used as a modified crosslinking agent to embed it into the gaps between the silicon oxide nanowires to form a mechanical locking structure.

Images