Hard inorganic particle reinforced aluminum alloy surface composite coating and preparation method thereof

Abstract

The invention discloses a hard inorganic particle reinforced aluminum alloy surface composite coating and a preparation method thereof, belongs to the technical field of metal coatings, and aims to solve the technical problem of low overall strength of a material due to the interface problem of additional reinforced particles in related technologies. The composite coating comprises an aluminum alloy matrix layer, a reinforcing layer and a transition layer located between the matrix layer and the reinforcing layer, and further comprises an interface layer and a composite layer, the interface layer is located between the transition layer and the reinforcing layer, and the composite layer is located between the interface layer and the reinforcing layer; the interface layer is a Ga-In-Sn liquid metal interface layer, and the thickness of the interface layer is 50-80 nm; the transition layer is an Al-Ti-Si nanocrystalline transition layer, and the thickness of the transition layer ranges from 200 nm to 300 nm. The composite layer is a SiC-Al2O3 composite layer formed by alternately overlapping SiC sheet layers and Al2O3 sheet layers, and the thickness of the composite layer is 1-2 [mu] m; the thickness of the sheet layer of the SiC-Al2O3 is 20 to 50 nm; and the thickness of the enhancement layer is 400-600 nm. Through interaction of all the layers, the bonding strength, the surface hardness and the abrasion resistance of the whole coating and the aluminum alloy matrix are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of metal coating technology, and in particular to a hard inorganic particle-reinforced aluminum alloy surface composite coating and its preparation method. Background Technology

[0002] Aluminum alloys have a low density (~2.7 g / cm³). 3 Due to their high specific strength, good thermal / electrical conductivity, formability, and recyclability, aluminum alloys are widely used in high-end manufacturing. However, aluminum alloys have low surface hardness (typically 80–150 HV), poor wear resistance, and are easily scratched and worn.

[0003] Existing technologies introduce high-hardness, high-stability, and low-density inorganic particles (such as SiC, Al2O3, B4C, TiC, etc.) onto the surface of aluminum alloys to construct a "surface composite functional layer," thereby enhancing the mechanical properties of the aluminum alloy surface while maintaining its low density and high strength. However, while this method improves stiffness, it often results in low overall material strength due to interface issues. Current technologies also suffer from the following problems: insufficient bonding strength between hard particles and the aluminum matrix, leading to particle detachment; a significant performance gradient abruptness between the surface hardened layer and the matrix, causing stress concentration; and traditional processing techniques struggle to simultaneously optimize surface hardness and overall toughness.

[0004] The aforementioned problems limit the further application of hard particle-reinforced aluminum alloys in fields such as aerospace and automotive. Summary of the Invention

[0005] This application discloses a composite coating for the surface of hard inorganic particles reinforced aluminum alloy and its preparation method, in order to solve the technical problems of insufficient bonding strength between hard particles and aluminum aggregate and stress concentration in related technologies.

[0006] To solve the above problems, this application adopts the following technical solution:

[0007] In a first aspect, this application proposes a hard inorganic particle reinforced aluminum alloy surface composite coating, including an aluminum alloy substrate layer, a reinforcing layer and a transition layer located between the substrate layer and the reinforcing layer, and also includes an interface layer and a composite layer, wherein the interface layer is located between the transition layer and the reinforcing layer, and the composite layer is located between the interface layer and the reinforcing layer.

[0008] Furthermore, the interface layer is a Ga-In-Sn liquid metal interface layer with a thickness of 50-80 nm.

[0009] Furthermore, the transition layer is an Al-Ti-Si nanocrystalline transition layer with a thickness of 200-300 nm.

[0010] Furthermore, the composite layer is a SiC-Al2O3 composite layer with alternating SiC sheets and Al2O3 sheets, and the thickness of the composite layer is 1-2 μm; the thickness of the SiC-Al2O3 sheets is 20-50 nm.

[0011] Furthermore, the thickness of the reinforcement layer is 400-600 nm.

[0012] Furthermore, the interface layer includes a first interface layer and a second interface layer. The first interface layer is located between the transition layer and the reinforcement layer, and the second interface layer exists between the substrate layer and the transition layer.

[0013] Furthermore, the transition layer includes spaced microchannels that connect the first interface layer and the second interface layer.

[0014] Furthermore, the interface layer consists of a first sublayer and a second sublayer. The first sublayer is in contact with the substrate layer, the transition layer, and the composite layer, and the second sublayer is located between the first sublayer. The first sublayer is a solid layer, and the second sublayer is a semi-solid layer. The thickness of the first sublayer is 10-30 nm, and the thickness of the second sublayer is 20-50 nm.

[0015] Furthermore, the sheet in contact between the SiC-Al2O3 composite layer and the interface layer is an Al2O3 sheet.

[0016] Furthermore, it also includes a protective layer located outside the reinforcement layer, which is a diamond-like carbon protective layer with a thickness of 50-100 nm.

[0017] Furthermore, by volume fraction, the reinforcing layer contains 30-70% particulate ceramic phase, and the ceramic phase changes in a gradient from the composite layer to the reinforcing layer, with the ceramic phase content gradually increasing along the gradient direction; the ceramic phase includes at least one of SiC, B4C and diamond particles.

[0018] Secondly, this application also provides a method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy, comprising the following steps:

[0019] Step 1: Perform ultrasonic cleaning and acid pickling activation treatment on the substrate layer;

[0020] Step 2: Deposit an Al-Ti-Si nanocrystalline transition layer on the activated substrate layer using reactive magnetron sputtering technology;

[0021] Step 3: Deposit a Ga-In-Sn liquid metal interface layer on the Al-Ti-Si nanocrystalline transition layer using metallurgical bonding technology;

[0022] Step 4: Construct a SiC-Al2O3 composite layer consisting of alternating SiC and Al2O3 sheets on the Ga-In-Sn liquid metal interface layer using pulsed laser deposition technology;

[0023] Step 5: Deposit a gradient ceramic reinforcement layer on the SiC-Al2O3 composite layer using magnetron sputtering and co-deposition techniques, wherein the volume fraction of the ceramic phase varies gradient along the thickness direction.

[0024] Furthermore, in step 2, a mold is set on the activated substrate layer, and then an Al-Ti-Si nanocrystalline transition layer is deposited to form microchannels.

[0025] Furthermore, after depositing the Al-Ti-Si nanocrystalline transition layer, micropores are fabricated in at least one of the micro-debonding region, weak bonding region, voids, and cracks of the transition layer to obtain microchannels.

[0026] Furthermore, in step 3, firstly, Ga-In-Sn liquid metal with a Ga content of 60-62 wt% is drop-coated onto the surface of the microchannel and transition layer to ensure full contact with the substrate layer and transition layer, with its thickness controlled at 10-30 nm; then, Ga-In-Sn liquid metal with a Ga content of 62-68 wt% is drop-coated, with its thickness controlled at 20-50 nm; then, Ga-In-Sn liquid metal with a Ga content of 58-60 wt% is drop-coated, with its thickness controlled at 10-30 nm; finally, the Ga-In-Sn liquid metal is subjected to in-situ low-temperature annealing for 10-60 min to obtain the Ga-In-Sn liquid metal interface layer, with the in-situ low-temperature annealing temperature being 50-80℃.

[0027] Furthermore, in step 4, when constructing the SiC-Al2O3 composite layer, Al2O3 sheets are deposited first, and then SiC sheets and Al2O3 sheets are deposited alternately.

[0028] Furthermore, the preparation method also includes step 6: depositing a diamond-like carbon protective layer on the gradient ceramic reinforcement layer by plasma-enhanced chemical vapor deposition or magnetron sputtering.

[0029] The technical solution adopted in this application can achieve the following beneficial effects:

[0030] The reinforcing layer is formed by densely packed nanoscale hard particles to improve surface scratch resistance, reduce the coefficient of friction, and seal the underlying micropores to enhance corrosion resistance.

[0031] The transition layer forms good metallurgical compatibility with the aluminum alloy matrix on the one hand, and provides a bearing platform with high surface energy and low defect density on the other hand, which significantly improves wettability and blocks the diffusion of Ga elements into the depth of the aluminum matrix, thereby mitigating the risk of liquid metal embrittlement.

[0032] At room temperature, Ga can significantly soften the Al surface and even induce a local liquid phase, thereby greatly reducing the interfacial tension and promoting wetting and atomic-level contact. Macroscopically, it presents a "solid-liquid-solid" three-layer structure, which has both high interfacial strength and excellent stress buffering capacity. It can effectively adapt to interfacial strain caused by thermal expansion mismatch or mechanical deformation and inhibit crack initiation and propagation.

[0033] The composite layered alternating structure effectively inhibits crack propagation, enhances fracture toughness through interlayer deflection mechanism, and provides structural transition and stress buffer;

[0034] Through the interaction of the above layers, the bonding strength, surface hardness, and wear resistance of the overall coating with the aluminum alloy substrate are significantly improved. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a longitudinal section schematic diagram of the composite coating on the surface of hard inorganic particle-reinforced aluminum alloy in some embodiments of this application;

[0037] Figure 2 This is a schematic diagram of the connection structure between the interface layer, the substrate layer, and the transition layer in some embodiments of this application;

[0038] Figure 3 This is a schematic flowchart of a method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy in some embodiments of this application.

[0039] In the picture:

[0040] 100, Matrix layer; 200, Transition layer; 210, Microchannel; 300, Interface layer; 310, First interface layer; 320, Second interface layer; 400, Composite layer; 500, Reinforcing layer; 600, Protective layer. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0043] Existing technologies introduce high-hardness, high-stability, and low-density inorganic particles (such as SiC, Al2O3, B4C, TiC, etc.) onto the surface of aluminum alloys to construct a "surface composite functional layer," thereby enhancing the mechanical properties of the aluminum alloy surface while maintaining its low density and high strength. However, while this method improves stiffness, it often results in low overall material strength due to interface issues. This limits the further application of hard particle-reinforced aluminum alloys in aerospace, automotive, and other fields.

[0044] This application effectively solves the technical problems of existing hard particle coatings on aluminum alloy surfaces, such as weak adhesion, easy cracking, particle agglomeration, and limited functionality, by constructing a five-layer gradient structure consisting of a substrate layer, a transition layer, an interface layer, a composite layer, and a reinforcement layer. The synergistic effect of each layer ensures both high hardness and wear resistance of the coating, while also maintaining strong interfacial bonding with the lightweight aluminum alloy substrate and ensuring service reliability. This makes it suitable for fields with stringent requirements for both lightweighting and surface performance, such as aerospace, new energy vehicles, and high-end electronic equipment.

[0045] The following is in conjunction with the appendix Figures 1 to 3 The present application provides a detailed description of the hard inorganic particle-reinforced aluminum alloy surface composite coating and its preparation method through specific embodiments and application scenarios.

[0046] Firstly, such as Figure 1 and Figure 2 As shown, this application proposes a hard inorganic particle reinforced aluminum alloy surface composite coating, including an aluminum alloy substrate layer 100, a reinforcing layer 500 and a transition layer 200 located between the substrate layer 100 and the reinforcing layer 500, and also includes an interface layer 300 and a composite layer 400, wherein the interface layer 300 is located between the transition layer 200 and the reinforcing layer 500, and the composite layer 400 is located between the interface layer 300 and the reinforcing layer 500.

[0047] Specifically, the aluminum alloy substrate layer 100 is made of 6061, 7075 or 2024 series aluminum alloy, which serves as the main load-bearing component and provides lightweight structural support.

[0048] For example, such as Figure 1 As shown, the reinforcement layer 500 is located on the outermost side and is formed by the dense stacking of nanoscale hard particles (such as nano SiC and nano Al2O3), or by obtaining a smooth and dense surface through sol-gel sealing treatment. The thickness is 400-600 nm. It is mainly used to improve the surface scratch resistance, reduce the coefficient of friction, and seal the micropores in the lower layer to enhance corrosion resistance.

[0049] For example, such as Figure 1 and Figure 2 As shown, the Al-Ti-Si nanocrystalline transition layer 200 was deposited in situ on the surface of an aluminum alloy substrate using a magnetron co-sputtering process. The target materials used were high-purity Al (99.99%), Ti (99.95%), and Si (99.999%) targets, and the sputtering atmosphere was high-purity Ar (purity ≥99.999%). During the deposition process, the substrate temperature was maintained at 80-120℃ to avoid thermal damage and promote nanocrystal formation.

[0050] The chemical composition of the resulting transition layer 200 is Al 85 Ti10Si5 (atomic percentage), this 200-300 nm thick Al-Ti-Si nanocrystalline transition layer 200, on the one hand, forms good metallurgical compatibility with the aluminum alloy matrix, and on the other hand, provides a high surface energy and low defect density support platform for the subsequent Ga-In-Sn liquid metal interface layer 300 or gradient ceramic reinforcement layer 500, significantly improving wettability and blocking the diffusion of Ga elements into the depth of the aluminum matrix, thereby mitigating the risk of liquid metal embrittlement.

[0051] For example, such as Figure 1 and Figure 2 As shown, the Ga-In-Sn liquid metal interface layer 300 is prepared using a high-purity gallium indium tin liquid alloy through an inert atmosphere-assisted spin-coating-annealing process to obtain a liquid metal film with uniform thickness. Although the Ga element in the Ga-In-Sn layer has a tendency to diffuse into the aluminum substrate, it is effectively blocked by the dense Al-Ti-Si nanocrystalline layer, thereby ensuring high conductivity while suppressing the occurrence of liquid metal embrittlement. At the same time, there is a significant metallurgical interaction between Ga and the metallic Al phase in the Al-Ti-Si nanocrystalline transition layer 200, and the metallic Al phase in the SiC-Al2O3 composite layer 400, which can promote interface wetting and bonding. Ga and Al are infinitely miscible in both liquid and solid states, forming a continuous solid solution. Therefore, at room temperature, Ga can significantly soften the Al surface and even induce a local liquid phase, thereby greatly reducing the interfacial tension and promoting wetting and atomic-level contact.

[0052] Furthermore, when the Ga-In-Sn liquid metal interface layer 300 is sandwiched between the Al-Ti-Si transition layer 200 and the SiC-Al2O3 composite layer 400, Ga elements spontaneously undergo selective diffusion and chemical affinity bonding to the Al-containing phases on both sides. This process leads to a decrease in Ga concentration in the near-interface region above and below the Ga-In-Sn layer, while In and Sn become relatively enriched. Since Ga is the key component determining the melting point of the Ga-In-Sn alloy (the higher its content, the lower the melting point), the local consumption of Ga causes a local increase in the melting point of the alloy near the interface.

[0053] By precisely controlling the initial composition of the Ga-In-Sn alloy (e.g., Ga content of 58-62 wt%) and diffusion kinetics (e.g., interfacial contact time, temperature, and Al phase exposure area), the region within approximately 10-30 nm above and below the Ga-In-Sn layer can be transformed into a solid state at room temperature. This solidifies the Ga-In-Sn layer with Al phases in the Al-Ti-Si transition layer 200 and the SiC-Al2O3 composite layer 400 on both sides, forming Al-Ga metallic bonds and even partially covalent / ionic interfacial chemical bonds, thereby significantly improving the interfacial bonding strength and thermal / electrical stability.

[0054] Meanwhile, the central region of the Ga-In-Sn layer remains a low-viscosity semi-solid, exhibiting a macroscopic "solid-liquid-solid" three-layer structure. This structure possesses: high interfacial strength (derived from the chemical bonding of the solidified regions on both sides); and excellent stress buffering capacity (derived from the zero shear modulus and flowability of the central semi-solid region), effectively adapting to interfacial strain caused by thermal expansion mismatch or mechanical deformation, and suppressing crack initiation and propagation.

[0055] For example, such as Figure 1As shown, the SiC-Al2O3 composite layer 400 is prepared by pulsed laser deposition: first, a 30 nm thick Al2O3 sheet is deposited on the surface of the Ga-In-Sn liquid metal interface layer 300; then, a 40 nm thick amorphous / nanocrystalline SiC sheet is deposited; the above deposition steps of Al2O3 sheet and SiC sheet are alternately repeated 30-40 times, finally forming an alternating stacked structure with a total thickness of 1.05-1.4 μm (where the volume ratio of Al2O3 sheet to SiC sheet is approximately 1:1.3). Among them, the Al2O3 sheets provide high insulation, chemical inertness and diffusion barrier to Ga elements; the SiC sheets impart high thermal conductivity (theoretical value >120 W / m·K), high hardness and good interfacial compatibility with the metal phase; the nanoscale alternating structure (20-50 nm / layer) effectively inhibits crack propagation and improves fracture toughness through interlayer deflection mechanism; the overall composite layer 400 serves as the bottom layer of the reinforcing layer 500, forming a low thermal resistance contact with the underlying Ga-In-Sn liquid metal interface layer 300 (thickness of 50-80 nm), and providing structural transition and stress buffer for the upper high ceramic content gradient reinforcing layer 500 (such as containing diamond / B4C).

[0056] Furthermore, the layers are metallurgically bonded or strongly mechanically interlocked, the overall coating has a bonding strength with the aluminum alloy substrate of ≥40 MPa, the microhardness is increased from 100-150 HV in the substrate to 1000-1500 HV in the surface layer, and the wear rate under dry sliding wear conditions is reduced by more than 80% compared with the untreated aluminum alloy.

[0057] In some embodiments, the interface layer 300 includes a first interface layer 310 and a second interface layer 320, the first interface layer 310 being located between the transition layer 200 and the reinforcement layer 500, and the second interface layer 320 existing between the substrate layer 100 and the transition layer 200.

[0058] For example, such as Figure 1 and Figure 2 As shown, the substrate layer 100 is made of 6061 aluminum alloy, and its surface is sequentially constructed with the following: second interface layer 320: Ga-In-Sn liquid metal layer with a thickness of 50-80 nm; transition layer 200: Al-Ti-Si nanocrystalline layer with a thickness of 250 nm; first interface layer 310: Ga-In-Sn liquid metal layer with a thickness of 60-75 nm.

[0059] In this structure, the second interface layer 320 primarily functions to improve the initial wettability between the aluminum alloy substrate and the Al-Ti-Si transition layer 200; promote atomic interdiffusion during low-temperature bonding to form a low-resistance electrical / thermal pathway; and suppress liquid metal embrittlement by utilizing the blocking effect of the Al-Ti-Si layer on Ga diffusion. The first interface layer 310, on the other hand, absorbs the thermo-mechanical mismatch stress between the reinforcing layer 500 and the transition layer 200; fills the micropores at the bottom of the gradient reinforcing layer 500 to reduce interfacial thermal resistance; and achieves self-repair of microcracks during service through the flow in the central liquid region.

[0060] The dual-interface-layer 300 design is significantly superior to the single-interface-layer 300 scheme, with a shear strength retention rate of >92% after thermal cycling, while the single-interface control group only has 68%.

[0061] In some embodiments, the transition layer 200 includes spaced microchannels 210 that connect the first interface layer 310 and the second interface layer 320.

[0062] For example, such as Figure 1 and Figure 2 As shown, the transition layer 200 is an Al-Ti-Si nanocrystalline layer with a thickness of 250 nm. Within it, a periodically distributed array of vertical microchannels 210 is formed through focused ion beam (FIB) etching or template-assisted sputtering. The microchannels 210 have a diameter of 500-900 nm, penetrate the entire transition layer 200, and are arranged in a hexagonal or square pattern. The upper and lower ends of the microchannels 210 are directly connected to the first interface layer 310 on the upper surface and the second interface layer 320 on the lower surface of the transition layer 200, respectively, forming a continuous capillary network. The microchannel 210 structure can promote capillary self-filling of Ga-In-Sn alloys. During the coating process of interface layer 300, liquid metal spontaneously wets the upper and lower interfaces through microchannel 210 under capillary force, achieving three-dimensional interconnection and significantly improving the uniformity of interface bonding. It can also enhance element diffusion channels, allowing Ga atoms to undergo limited exchange between the first and second interface layers 320 through microchannel 210, synergistically regulating the local composition and phase state of the two interfaces. The microchannel 210 structure can also provide stress relief paths. Under thermal cycling or mechanical loads, microchannel 210 can accommodate the volume flow of liquid metal, alleviating interface shear stress concentration and inhibiting crack propagation along the planar direction. The microchannel 210 structure can also improve the longitudinal conduction efficiency of electricity / heat. The continuous Ga-In-Sn filling channels form a low-resistance pathway, effectively reducing the cross-layer thermal resistance.

[0063] Furthermore, since the inner wall of the microchannel 210 is exposed to the Al-Ti-Si nanocrystalline environment and is rich in Ti and Si elements, a thin Ti-Ga or Si-O-Ga interface passivation film can be formed in situ after contact with liquid metal, which can prevent excessive Ga erosion of the substrate and maintain the long-term patency of the channel.

[0064] In this embodiment, the traditional two-dimensional interface is extended into a three-dimensional interconnect interface system, which significantly improves the overall integration reliability and multifunctionality of the multilayer heterostructure while maintaining the blocking function of the Al-Ti-Si transition layer 200.

[0065] In some embodiments, the interface layer 300 consists of a first sublayer and a second sublayer. The first sublayer is in contact with the substrate layer 100, the transition layer 200, and the composite layer 400, and the second sublayer is located between the first sublayer. The first sublayer is a solid layer, and the second sublayer is a semi-solid layer. The thickness of the first sublayer is 10-30 nm, and the thickness of the second sublayer is 20-50 nm. The sheet in contact between the SiC-Al2O3 composite layer 400 and the interface layer 300 is an Al2O3 sheet.

[0066] For example, such as Figure 1 and Figure 2 As shown, the Ga-In-Sn interface layer 300 is not a homogeneous liquid film, but a sandwich-like heterolayer structure formed through the self-evolution of compositional gradients: the top and bottom are first sublayers (each approximately 15 nm thick), with a second sublayer (approximately 30 nm thick) sandwiched in the middle. Specifically, during the interface integration process, the Ga-In-Sn alloy contacts the Al phase in the lower Al-Ti-Si transition layer 200 and the Al2O3 sheets at the bottom of the upper SiC-Al2O3 composite layer 400, respectively. Although Al2O3 itself does not react directly with Ga, the trace amounts of hydroxyl groups or defect sites adsorbed on its surface can promote the selective diffusion of Ga to adjacent Al-rich regions (such as the Al-Ti-Si layer or the residual metallic Al phase in the composite layer 400). This process leads to the consumption of Ga near the interface, causing the Ga content in the Ga-In-Sn region adjacent to the two solid layers to decrease below the eutectic threshold, thereby spontaneously transforming into a high-viscosity solid or nanocrystalline dispersed strengthening phase at room temperature, forming the first sublayer. The intermediate region, where the Ga concentration remains near the eutectic composition, exhibits semi-solid characteristics at room temperature, forming the second sublayer. This semi-solid layer has an extremely low shear modulus, effectively dissipating interfacial strain caused by heat dissipation-mechanical cycles and preventing brittle cracking. The side of the SiC-Al2O3 composite layer 400 that directly contacts the interface layer 300 is designed as an Al2O3 sheet (30 nm thick) instead of a SiC sheet.

[0067] In some embodiments, a protective layer 600 is further included outside the reinforcing layer 500. The protective layer 600 is a diamond-like carbon protective layer 600 with a thickness of 50-100 nm.

[0068] For example, such as Figure 1As shown, the protective layer 600 is a diamond-like carbon (DLC) protective layer 600. The protective layer 600 is deposited in situ on the surface of the completed gradient ceramic reinforcement layer 500 using a mid-frequency magnetron sputtering or plasma-enhanced chemical vapor deposition (PECVD) process, resulting in a hydrogenated diamond-like carbon film with a thickness of 80 nm. This DLC protective layer 600 exhibits high hardness and wear resistance, significantly improving surface scratch resistance and fretting wear resistance, making it suitable for high-friction or harsh service environments. It also possesses excellent chemical inertness, and its dense amorphous structure effectively prevents the penetration of water vapor, oxygen, and corrosive media.

[0069] In this embodiment, the DLC protective layer 600 balances protection, functionality, and reliability without significantly increasing structural stiffness.

[0070] In some embodiments, the reinforcing layer 500 contains 30-70% particulate ceramic phase by volume fraction, and the ceramic phase varies in a gradient from the composite layer 400 to the reinforcing layer 500, with the ceramic phase content gradually increasing along the gradient direction; the ceramic phase includes at least one of SiC, B4C and diamond particles.

[0071] For example, such as Figure 1 As shown, the reinforcing layer 500 can be prepared by layer-by-layer deposition or gradient spraying, with a thickness of 400-600 nm. On the side close to the aluminum alloy substrate layer 100, the ceramic phase volume fraction is 30%, mainly composed of nano-sized SiC particles (average particle size <100 nm); along the thickness direction outward (i.e. away from the substrate), the ceramic phase content gradually increases, reaching 65-70% in the surface region, and a mixed phase of diamond particles (particle size 20-100 nm) and B4C particles (particle size 20-100 nm) with high thermal conductivity is introduced to synergistically improve surface hardness, wear resistance and thermal diffusion capacity.

[0072] Secondly, such as Figure 3 As shown, this application also provides a method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy, comprising the following steps:

[0073] Step 1: Surface activation treatment of substrate layer 100:

[0074] The aluminum alloy substrate layer 100 was ultrasonically cleaned for 5 minutes each in acetone, anhydrous ethanol, and deionized water to remove surface oil and organic contaminants. Then, the cleaned substrate layer 100 was immersed in a 10 wt% HNO3 solution for 30 seconds to selectively dissolve the natural Al2O3 film and activate the surface. It was immediately rinsed with deionized water and dried with high-purity nitrogen to avoid secondary oxidation.

[0075] Step 2: Construction of Al-Ti-Si nanocrystalline transition layer 200 and microchannel 210:

[0076] A sputtering-resistant mask (such as a molybdenum or quartz mold) with a preset pattern is attached to the surface of the activated substrate layer 100. Reactive magnetron sputtering technology is used, with an Al-Ti alloy target and a high-purity Si target as co-sputtering sources. An Ar / N2 mixed gas (N2 content 5-10 vol%) is introduced. Under the conditions of substrate bias voltage -30 V and deposition temperature 100℃, an Al-Ti-Si nanocrystalline transition layer 200 with a thickness of 200-300 nm is deposited.

[0077] After deposition, the mask is removed, and vertically penetrating micropores are precisely machined at the micro-debonding zone, weak bonding zone, voids and cracks in the transition layer 200 using focused ion beam (FIB) or femtosecond laser micromachining technology. This forms a microchannel 210 array with a diameter of 500-900 nm, enabling the directional transport and interface anchoring of subsequent liquid metal.

[0078] Step 3: Construction of a gradient composition Ga-In-Sn liquid metal interface layer 300:

[0079] First, Ga-In-Sn liquid metal with a Ga content of 60-62 wt% (the balance being In / Sn) is dropped onto the surface of microchannel 210 and transition layer 200. The mixture is then left to stand in an inert atmosphere glove box for 5 min to allow it to fully wet microchannel 210 and come into contact with Al-Ti-Si layer through capillary action. The thickness of this bottom layer is controlled to be 10-30 nm.

[0080] Subsequently, a Ga-In-Sn alloy with a Ga content of 62-68 wt% was added dropwise to form an intermediate layer with a thickness controlled at 20-50 nm.

[0081] Then, a Ga-In-Sn alloy with a Ga content of 58-60 wt% is added dropwise to form a top layer with a thickness of 10-30 nm;

[0082] Finally, in-situ low-temperature annealing is performed at 50-80℃ for 10-60 min. During this process, Ga selectively diffuses into the Al-containing phases above and below, resulting in a decrease in Ga concentration and an increase in melting point in the near-interface region, ultimately forming a structural interface layer 300 consisting of a "solid first sublayer / semi-solid second sublayer / solid first sublayer," which combines high bonding strength with stress buffering capacity.

[0083] Step 4: Deposition of SiC-Al2O3 alternating composite layer at 400:

[0084] Pulsed laser deposition (PLD) was used to first deposit a 30 nm thick Al₂O₃ sheet on the Ga-In-Sn interface layer 300 (to ensure good compatibility with the liquid metal side). Subsequently, SiC sheets (20-50 nm) and Al₂O₃ sheets (20-50 nm) were alternately deposited, repeated for 10-20 cycles to obtain a SiC-Al₂O₃ nanolayered composite structure with a total thickness of 1-2 μm. The deposition process was carried out in an oxygen / argon mixed atmosphere, with the substrate temperature controlled at ≤80℃ to prevent disturbance of the Ga-In-Sn layer.

[0085] Step 5: Preparation of gradient ceramic reinforcement layer 500:

[0086] By employing a combination of magnetron sputtering and powder co-deposition technology, an Al metal matrix and hard ceramic particles (at least one of SiC, B4C, and / or diamond) are simultaneously introduced onto the SiC-Al2O3 composite layer 400. By controlling the ceramic feed rate in real time, the volume fraction of the ceramic phase is continuously increased from 30 vol% in the bottom layer to 70 vol% in the surface layer, forming a gradient reinforcement layer 500 with a thickness of 400-600 μm.

[0087] Step 6: Deposition of Diamond-like Carbon (DLC) Protective Layer 600:

[0088] Finally, a 50-100 nm thick hydrogenated diamond-like carbon protective layer 600 is deposited on the surface of the gradient ceramic reinforcement layer 500 using plasma-enhanced chemical vapor deposition (PECVD) or mid-frequency magnetron sputtering technology at a deposition temperature ≤100℃ to provide high hardness, wear resistance and environmental barrier properties.

[0089] For example, the composite coating obtained on the surface of 6061-T6 aluminum alloy using the above method has a shear strength of 42 MPa at room temperature, a strength retention rate of >90% after 1000 thermal cycles from -55℃ to 125℃, a vertical thermal conductivity of 85 W / (m·K), and a surface hardness of >18 GPa. It combines high reliability, high thermal conductivity, and excellent environmental durability, making it suitable for heat dissipation substrates for high-power electronic devices, lightweight wear-resistant components for aerospace, and flexible heterogeneous integrated systems.

[0090] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0091] Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0092] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A hard inorganic particle-reinforced aluminum alloy surface composite coating, comprising an aluminum alloy substrate layer (100), a reinforcing layer (500), and a transition layer (200) located between the substrate layer (100) and the reinforcing layer (500), characterized in that, It also includes an interface layer (300) and a composite layer (400), wherein the interface layer (300) is located between the transition layer (200) and the reinforcement layer (500), and the composite layer (400) is located between the interface layer (300) and the reinforcement layer (500); The interface layer (300) is a Ga-In-Sn liquid metal interface layer (300) with a thickness of 50-80 nm. The transition layer (200) is an Al-Ti-Si nanocrystalline transition layer (200), and its thickness is 200-300 nm; The composite layer (400) is a SiC-Al2O3 composite layer (400) in which SiC sheets and Al2O3 sheets are alternately stacked, and the thickness of the composite layer (400) is 1-2 μm; the thickness of the SiC-Al2O3 sheets is 20-50 nm. The thickness of the reinforcement layer (500) is 400-600 nm.

2. The hard inorganic particle-reinforced aluminum alloy surface composite coating according to claim 1, characterized in that, The interface layer (300) includes a first interface layer (310) and a second interface layer (320). The first interface layer (310) is located between the transition layer (200) and the reinforcement layer (500), and the second interface layer (320) exists between the substrate layer (100) and the transition layer (200).

3. The hard inorganic particle-reinforced aluminum alloy surface composite coating according to claim 2, characterized in that, The transition layer (200) includes spaced microchannels (210) that connect the first interface layer (310) and the second interface layer (320).

4. The hard inorganic particle-reinforced aluminum alloy surface composite coating according to claim 2, characterized in that, The interface layer (300) is composed of a first sublayer and a second sublayer. The first sublayer is in contact with the substrate layer (100), the transition layer (200), and the composite layer (400). The second sublayer is located between the first sublayer. The first sublayer is a solid layer, and the second sublayer is a semi-solid layer. The thickness of the first sublayer is 10-30 nm, and the thickness of the second sublayer is 20-50 nm. The sheet in contact between the SiC-Al2O3 composite layer (400) and the interface layer (300) is an Al2O3 sheet.

5. The hard inorganic particle-reinforced aluminum alloy surface composite coating according to claim 1, characterized in that, It also includes a protective layer (600) located outside the reinforcing layer (500), the protective layer (600) being a diamond-like carbon protective layer (600) with a thickness of 50-100 nm.

6. The hard inorganic particle-reinforced aluminum alloy surface composite coating according to claim 1, characterized in that, The reinforcing layer (500) contains 30-70% particulate ceramic phase by volume fraction, and the ceramic phase changes in a gradient from the composite layer (400) to the reinforcing layer (500), with the ceramic phase content gradually increasing along the gradient direction; the ceramic phase includes at least one of SiC, B4C and diamond particles.

7. A method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Perform ultrasonic cleaning and acid pickling activation treatment on the substrate layer (100); Step 2: Deposit an Al-Ti-Si nanocrystalline transition layer (200) on the activated substrate layer (100) using reactive magnetron sputtering. Step 3: Deposit a Ga-In-Sn liquid metal interface layer (300) on the Al-Ti-Si nanocrystalline transition layer (200) using metallurgical bonding technology. Step 4: Using pulsed laser deposition technology, a SiC-Al2O3 composite layer (400) consisting of alternating SiC and Al2O3 sheets is constructed on the Ga-In-Sn liquid metal interface layer (300). Step 5: Deposit a gradient ceramic reinforcement layer (500) on the SiC-Al2O3 composite layer (400) using magnetron sputtering and co-deposition techniques, wherein the volume fraction of the ceramic phase varies in a gradient along the thickness direction.

8. The method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy according to claim 7, characterized in that, In step 2, a mold is set on the activated substrate layer (100), and then an Al-Ti-Si nanocrystalline transition layer (200) is deposited to form microchannels (210). And / or, after depositing an Al-Ti-Si nanocrystalline transition layer (200), micropores are processed on at least one of the micro-debonding region, weak bonding region, voids and cracks in the transition layer (200) to obtain microchannels (210).

9. The method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy according to claim 8, characterized in that, In step 3, firstly, Ga-In-Sn liquid metal with a Ga content of 60-62 wt% is drop-coated onto the surface of the microchannel (210) and the transition layer (200) to ensure full contact with the substrate layer (100) and the transition layer (200), with a thickness controlled to be 10-30 nm; then, Ga-In-Sn liquid metal with a Ga content of 62-68 wt% is drop-coated, with a thickness controlled to be 20-50 nm; then, Ga-In-Sn liquid metal with a Ga content of 58-60 wt% is drop-coated, with a thickness controlled to be 10-30 nm; finally, the Ga-In-Sn liquid metal is subjected to in-situ low-temperature annealing for 10-60 min to obtain a Ga-In-Sn liquid metal interface layer (300), wherein the in-situ low-temperature annealing temperature is 50-80 °C. In step 4, when constructing the SiC-Al2O3 composite layer (400), the Al2O3 sheet is deposited first, and then the SiC sheet and the Al2O3 sheet are deposited alternately.

10. The method for preparing a composite coating on the surface of a hard inorganic particle-reinforced aluminum alloy according to claim 7, characterized in that, The preparation method further includes step 6: depositing a diamond-like carbon protective layer (600) on the gradient ceramic reinforcement layer (500) by plasma-enhanced chemical vapor deposition or magnetron sputtering.

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