Modified carbon fiber material for unmanned aerial vehicles and process for processing the same

Abstract

The application relates to the field of unmanned aerial vehicle materials and discloses a modified carbon fiber material for an unmanned aerial vehicle, which comprises the following structure layers: a carbon fiber base body, a Ni-Ti transition layer deposited on the surface of the base body, the thickness of the Ni-Ti transition layer being 18-22 mu m, the mass ratio of Ni to Ti being 49.5:50.5-50.5:49.5, and a nano composite coating layer covering the transition layer, the nano composite coating layer comprising a nickel sulfamate base body and dispersed nano alpha-Al2O3 and silicon carbide whiskers in the nickel sulfamate base body, wherein the content of Al2O3 is 78-82 g / L, and the content of silicon carbide whiskers is 14-16 g / L. Through gradient composite interface structure design, the application realizes cross-scale synergistic reinforcement of a metal base body, a ceramic layer and a resin layer, further enhances the synergistic effect of chemical bonding and physical anchoring, and enables the material to still maintain excellent interface stability under a thermal coupling environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unmanned aerial vehicle materials, and particularly relates to a modified carbon fiber material for unmanned aerial vehicles and a processing technology thereof. BACKGROUND

[0002] Carbon fiber composite materials have become the core materials of lightweight structural components of unmanned aerial vehicles due to their high specific strength and low thermal expansion coefficient characteristics. The existing technology focuses on carbon fiber surface modification, composite reinforcement phase introduction and interface optimization, involving plasma activation, magnetron sputtering coating, micro-arc oxidation ceramicization, resin matrix hybridization and other processes. Related research focuses on single performance improvement, such as improving wear resistance through nanoparticle dispersion strengthening, or relieving interface thermal stress through gradient coating design.

[0003] The current technical system has multiple bottlenecks in the synergistic reinforcement of the carbon fiber-metal-resin interface: the existing carbon fiber composite materials still face problems such as interlayer cracking caused by insufficient interface bonding strength, thermal stress failure caused by the difference in thermal expansion coefficient of heterogeneous materials, poor erosion resistance caused by uneven dispersion of nano-enhanced phase, and poor batch stability caused by mismatch of multi-process parameters, which seriously restrict the reliability and service life of the materials in extreme environments. SUMMARY

[0004] The purpose of the present application is to provide a modified carbon fiber material for unmanned aerial vehicles and a processing technology thereof, which solves the problems of interlayer cracking caused by insufficient interface bonding strength, thermal stress failure caused by mismatch of thermal expansion coefficient of heterogeneous materials, insufficient erosion resistance caused by uneven dispersion of nano-enhanced phase, and poor batch stability caused by poor synergistic performance of multi-process parameters.

[0005] To achieve the above purpose, the technical scheme is as follows:

[0006] A modified carbon fiber material for unmanned aerial vehicles, comprising the following structure layers:

[0007] A carbon fiber matrix;

[0008] As the main body load-bearing structure, a high-modulus carbon fiber woven body or a prepreg is selected. The surface of the matrix is pretreated by plasma activation to form a micro-nano rough structure and introduce oxygen-containing functional groups. This treatment does not change the mechanical properties of the carbon fiber body, but provides active sites for the chemical bonding of the subsequent metal layer, avoiding the fiber damage problem of traditional mechanical polishing.

[0009] A Ni-Ti transition layer deposited on the surface of the matrix, with a thickness of 18-22 microns and a mass ratio of Ni to Ti of 49.5:50.5-50.5:49.5;

[0010] The quasi-equiatomic nature of Ni-Ti alloy makes it have high ductility and moderate thermal expansion coefficient, which effectively relieves the thermal mismatch stress between carbon fiber (CTE≈0) and subsequent metal coating (Ni-based coating, CTE≈13×10 -6 / ℃).

[0011] The amorphous phase (60-70%) can inhibit crack propagation, and the nanocrystalline phase (size <50 nm) provides load capacity, and the composite structure of the two makes the transition layer still maintain interface integrity under thermal cycle load.

[0012] The nanocomposite coating covering the transition layer comprises a nickel sulfamate matrix and dispersed nanometer α-Al2O3 and silicon carbide whiskers, wherein the content of Al2O3 is 78-82 g / L, and the content of silicon carbide whiskers is 14-16 g / L.

[0013] Nanometer α-Al2O3 (hardness HV≥2000) as a hard reinforcing phase improves the wear resistance of the coating; silicon carbide whiskers (aspect ratio >20) toughen by bridging and pulling out mechanism to inhibit brittle cracking of the coating.

[0014] Using a nickel sulfamate system (not a watt nickel) reduces the stress in the plating solution, combined with the current reversing effect of a three-pulse power supply, forcing the nanoparticles to arrange in the coating, avoiding the agglomeration defects of conventional direct current plating.

[0015] The epoxy-silane hybrid protective layer coated on the surface of the composite coating comprises 94-96 wt% epoxy resin E51, 7.5-8.5 wt% APTES, and 4.8-5.2 wt% POSS.

[0016] The amino group in APTES reacts with the epoxy group, and its siloxane hydrolysis product condenses with the metal hydroxyl group on the surface of the coating, realizing chemical bonding between the resin-metal interface.

[0017] The POSS nanocage structure (particle size 20-30 nm) as a physical crosslinking point is embedded in the epoxy network, inhibiting crack propagation through steric hindrance effect, while improving the heat resistance of the resin layer (Tg increase ≥30℃).

[0018] Preferably, the Ni-Ti transition layer is prepared by magnetron sputtering, with a sputtering power of 280-320 W, a substrate temperature of 180-220℃, and a deposition rate of 0.45-0.55 nm / s.

[0019] The sputtering power is set to 280-320 W, which is determined by balancing the target ionization rate and film quality. When the power is lower than 280 W, the plasma density is insufficient, resulting in a too low deposition rate (<0.4 nm / s) and micro-pore defects caused by incompletely ionized metal clusters in the film. When the power is higher than 320 W, although the deposition rate is improved, the thermal stress caused by high-energy particle bombardment of the substrate will cause micro-cracks in the film, and the high sputtering kinetic energy will damage the plasma-activated layer on the surface of the carbon fiber.

[0020] The power window of 280-320 W ensures effective ionization of the Ni-Ti target, so that the deposition particles have a moderate kinetic energy (10-20 eV), which ensures film density and avoids structural damage to the carbon fiber substrate. In this power range, the sputtering yield ratio of Ni and Ti atoms is stable at 0.98-1.02, thereby precisely maintaining the equal atomic ratio characteristic of the alloy composition.

[0021] In the range of 180-220℃, the deposition atoms have moderate surface diffusion ability, promoting the synergistic growth of amorphous and nanocrystalline phases (grain size <50 nm). The amorphous phase (60-70%) absorbs interface stress through disordered structure, and the nanocrystalline phase provides bearing capacity. The film structure formed by the combination of the two can effectively inhibit crack initiation, and the difference in thermal expansion coefficient (ΔCTE <4×10 -6 / ℃) with the carbon fiber substrate is controlled within a safe threshold.

[0022] Preferably, the modified carbon fiber material for unmanned aerial vehicles is characterized in that the particle size of nano α-Al2O3 in the nanocomposite coating is 45-55 nm, the diameter of silicon carbide whiskers is 180-220 nm, and the coating thickness is 78-82 μm.

[0023] The particle size of nano α-Al2O3 is strictly limited to the range of 45-55 nm, which is determined by balancing the surface energy of the nanoparticles and their Brownian motion ability in the plating solution. When the particle size is less than 45 nm, the surface energy of the particles increases significantly, leading to irreversible agglomeration of the particles in the nickel sulfamate plating solution due to van der Waals forces, forming micron-sized particle clusters. When the particle size is greater than 55 nm, the specific surface area of the particles decreases, reducing the contact interface with the nickel matrix, resulting in a decrease in dispersion strengthening effect.

[0024] The α-Al2O3 particles with a particle size of 45-55 nm have a surface charge (Zeta potential ≈ +25 mV) in the pulsed electroplating process, which is balanced with the sulfamate ions (-SO3 -) form electrostatic repulsion, effectively inhibit the particle agglomeration. At the same time, the settling rate of the size particles (0.02-0.03 mm / s calculated by Stokes formula) matches the plating solution circulation flow rate (0.5-0.8 m / s), ensuring its uniform suspension in the plating solution.

[0025] The silicon carbide whisker diameter is set to 180-220 nm, which is based on the matching principle of whisker bending strength and plating layer internal stress. When the diameter is less than 180 nm, the whisker is easily broken by fluid shear force in the electroplating process, losing the toughening effect; when the diameter is greater than 220 nm, the difference in thermal expansion coefficient (ΔCTE≈4×10 -6 / ℃) between the whisker and the nickel matrix causes interface stress concentration, becoming a crack initiation source.

[0026] The plating layer thickness is controlled to be 78-82 μm, which is determined by the comprehensive consideration of the plating layer internal stress gradient distribution and functional requirements. When the thickness is less than 78 μm, the plating layer has insufficient coverage integrity to the substrate, and local areas are caused to be corroded due to interface defects; when the thickness is greater than 82 μm, the residual stress (mainly caused by the difference in thermal expansion between the nickel matrix and the reinforcing phase) in the plating layer exceeds the critical value (>300 MPa), causing the plating layer to warp or peel off.

[0027] Preferably, the curing process of the epoxy-silane hybrid protective layer includes three stages:

[0028] The first stage: curing at 78-82 ℃ for 1.9-2.1 h, vacuum degree -0.094 to -0.096 MPa;

[0029] Curing at 78-82 ℃, vacuum degree -0.094 to -0.096 MPa for 1.9-2.1 h, this stage is mainly dominated by the preliminary crosslinking of the resin and the interface wetting. The vacuum environment forces the solvent and low molecular volatile substances (residual monomers, water molecules) in the resin to transform from liquid to gas, and is removed by negative pressure. The temperature is controlled to be above the glass transition temperature (Tg≈65 ℃) of the epoxy resin, but lower than the rapid curing starting temperature (≈90 ℃) thereof, ensuring that the molecular chain segments have moderate activity.

[0030] The second stage: curing at 118-122 ℃ for 0.95-1.05 h, vacuum degree -0.094 to -0.096 MPa;

[0031] The temperature is raised to 118-122 ℃, the vacuum degree is maintained at -0.094 to -0.096 MPa, and curing is performed for 0.95-1.05 h. In this stage, the epoxy resin enters the rapid crosslinking period, and the ring-opening reaction of APTS and epoxy groups is accelerated, and at the same time, the POSS nanoparticles begin to interpenetrate with the resin network. The vacuum environment continuously inhibits the rebirth of bubbles, and promotes the discharge of crosslinking by-products (water, alcohol).

[0032] Third stage: curing at 148-152°C for 0.48-0.52h in normal pressure environment.

[0033] Curing at 148-152°C for 0.48-0.52h in normal pressure environment, the resin network is deeply cross-linked and the residual stress is relaxed. The normal pressure allows oxygen to participate in the oxidation cross-linking on the surface of the resin, forming a dense surface layer. The temperature exceeds the final Tg of the resin (≈140°C), allowing the molecular chain segments to move sufficiently to eliminate internal defects.

[0034] Preferably, a porous ceramic layer generated by micro-arc oxidation is provided between the nano-composite coating and the Ni-Ti transition layer, with a porosity of 30-40% and a thickness of 8-12 μm.

[0035] The porosity of the porous ceramic layer is limited to 30-40%, which is based on the balance between the interface bonding strength and stress distribution of the pore structure. When the porosity is less than 30%, the ceramic layer presents a dense structure, with a significant difference in elastic modulus (≈200 GPa) compared to the Ni-Ti transition layer (≈80 GPa), leading to interface stress concentration; when the porosity is higher than 40%, although the elastic modulus decreases (≈120 GPa), the high connectivity of the pores weakens the mechanical anchoring effect of the coating and the transition layer.

[0036] The thickness of the ceramic layer is set to 8-12 μm, which is determined by the comprehensive needs of interface bonding strength and conductivity. When the thickness is less than 8 μm, the stress buffering capacity of the porous structure is insufficient, and the high voltage discharge (>400V) in the micro-arc oxidation process is easy to break through the transition layer; when the thickness is greater than 12 μm, the insulation property of the ceramic layer (resistivity >10 6 Ω·cm) leads to the need to apply excessively high voltage (>15V) during subsequent electroplating, causing the decomposition of the plating solution.

[0037] Under a thickness of 8-12 μm, the ceramic layer presents a gradient structure:

[0038] Near the transition layer region (0-3 μm): the porosity is relatively low (≈35%), rich in Al2O3-SiO2 amorphous phase, and realizes chemical bonding with the Ni-Ti layer through a diffusion interface (width ≈0.5 μm);

[0039] Intermediate region (3-8 μm): the porosity gradient rises to 40%, forming a dendritic pore network to provide a path for the penetration of the electroplating solution;

[0040] Surface layer region (8-12 μm): the pore opening diameter expands to 2-5 μm, and the surface is covered with nano-sized oxide particles (particle size ≈50 nm), increasing the contact area with the nano-composite coating.

[0041] The porous ceramic layer is formed synergistically through a specific electrolyte (Na₂SiO₃ 9.5–10.5 g / L + KOH 4.8–5.2 g / L) and electrical parameters (voltage 440–460 V, frequency 480–520 Hz). A high-voltage pulsed electric field induces plasma discharge on the surface of the Ni-Ti layer, and a melting-quenching cycle forms the porous oxide.

[0042] The pulse frequency of 480 to 520 Hz controls the duration of a single discharge to 10 to 20 μs and limits the size of the molten pool to 5 to 8 μm, thus avoiding pore closure caused by excessive sintering.

[0043] SiO3 in the electrolyte 2- It decomposes into SiO2 at high discharge temperatures (>3000K), and forms an amorphous-nanocrystalline composite ceramic phase with Al2O3 and TiO2 generated by the oxidation of the Ni-Ti layer;

[0044] During the micro-arc oxidation process, Ni elements on the surface of the Ni-Ti layer are selectively oxidized to generate NiO (content ≈15%), which forms a coherent interface with the Ni matrix of the subsequent nanocomposite coating, reducing the interface energy barrier.

[0045] A processing technology based on the above-mentioned modified carbon fiber material includes the following steps:

[0046] (a) Plasma activation treatment of carbon fiber matrix;

[0047] The carbon fiber surface was bombarded for 14–16 minutes with an Ar / O2 mixed gas (volume ratio 4:1 ± 0.2) at a radio frequency power of 450–550 W, while maintaining a vacuum of 8 × 10⁻⁶. -3 ~1.2×10 -2 Pa. The treated fiber surface forms nanoscale grooves (Ra = 0.8–1.2 μm) and introduces oxygen-containing functional groups (-COOH, -OH).

[0048] High-energy Ar + Ions selectively etch along the (002) direction of the carbon fiber graphite crystal plane to form nanogrooves at an angle of 45° to 60° with the fiber axis, increasing the specific surface area (by about 5 times);

[0049] In O2 plasma, reactive oxygen free radicals react with carbon surfaces to generate carboxyl and hydroxyl groups, with a concentration of 8–12 per nm. 2 This provides anchoring points for subsequent chemical bonding of the metal layer.

[0050] (b) Depositing a Ni-Ti transition layer on the activated surface by magnetron sputtering;

[0051] A Ni50Ti50 alloy layer was sputtered onto the activated carbon fiber surface at a power of 280–320 W, a substrate temperature of 180–220 °C, a deposition rate of 0.45–0.55 nm / s, and a final thickness of 18–22 μm.

[0052] A substrate temperature of 180–220℃ restricts the migration rate of sputtered particles on the surface, forming a composite film with an amorphous substrate (60–70%) encapsulating nanocrystals (size <50 nm). The coefficient of thermal expansion (CTE) is 10–12 × 10⁻⁶. -6 / ℃) is between carbon fiber (CTE≈0) and subsequent coating (CTE≈14×10) -6 A thermal stress gradient transition is achieved between / ℃;

[0053] The Ni / Ti sputtering yield ratio is stabilized at 0.98–1.02 through coordinated adjustment of power and gas pressure, ensuring that the alloy composition deviation is <±0.5%.

[0054] (c) Micro-arc oxidation treatment is performed on the surface of the transition layer to generate a porous ceramic layer;

[0055] A pulsed voltage of 440–460 V was applied to the surface of the Ni-Ti layer, and the electrolyte was Na2SiO3 (9.5–10.5 g / L) + KOH (4.8–5.2 g / L). After treatment for 9–11 min, an Al2O3-SiO2 composite ceramic layer with a thickness of 8–12 μm and a porosity of 30–40% was generated.

[0056] The pulse frequency of 480-520Hz ensures that the duration of a single discharge is ≤20μs, and the size of the molten pool is limited to 5-8μm, forming a composite structure of primary pores with a diameter of 1-3μm and secondary pores with a diameter of 50-200nm.

[0057] SiO3 in the electrolyte 2- At high discharge temperatures (>3000K), it decomposes into SiO2, which, together with Al2O3 and TiO2 generated from the oxidation of the Ni-Ti layer, forms an amorphous matrix (70-80%) encapsulating a ceramic layer of nanocrystalline phase (size 20-50 nm), with a surface hydroxyl density of 15-20 hydroxyl groups / nm. 2 .

[0058] (d) A nanocomposite coating was prepared on a porous ceramic layer using a three-pulse electroplating process;

[0059] Pulse electroplating was performed on the surface of the micro-arc oxide layer. The plating solution contained nickel sulfamate (375-385 g / L), nano α-Al2O3 (78-82 g / L), and silicon carbide whiskers (14-16 g / L). A three-pulse mode with a forward pulse width of 0.95-1.05 ms, a reverse pulse width of 0.18-0.22 ms, and an interval of 0.48-0.52 ms was adopted, and the current density J = 4.0-0.05C_{Al2O3} was dynamically adjusted.

[0060] High current density of positive pulse (4A / dm) 2 The nanoparticles are driven to adsorb onto the cathode surface, and the reverse pulse (0.2ms) dissolves the weakly adsorbed particles, thereby increasing the particle bonding strength of the final embedded coating by 2 to 3 times.

[0061] The coupling effect of cathode rotation (28-32 rpm) and ultrasound (36-40 kHz) breaks the boundary layer of the plating solution, making the distribution of nanoparticles in the pores of the micro-arc oxidation layer more uniform (CV value <5%).

[0062] (e) Spray epoxy-silane hybrid resin onto the surface of the composite coating and cure it under vacuum.

[0063] A hybrid resin containing epoxy resin E51 (94-96 wt%), APTES (7.5-8.5 wt%), and POSS (4.8-5.2 wt%) is sprayed onto the coating surface, with a film thickness of 0.48-0.52 mm. The coating is then cured in three stages under vacuum (78-82℃ / 1.9-2.1 h → 118-122℃ / 0.95-1.05 h → 148-152℃ / 0.48-0.52 h) to form a protective layer.

[0064] The siloxane groups of APTES hydrolyze to generate Si-OH, which condenses with the metal hydroxyl groups on the coating surface to form Si-OM covalent bonds with bond energies of 400-450 kJ / mol.

[0065] POSS nanocages (1-2 nm in diameter) are embedded in the epoxy crosslinking network, serving as physical crosslinking points to increase the resin modulus by 30-40%, while inhibiting crack propagation through steric hindrance.

[0066] Preferably, the parameters for plasma activation treatment in step (a) are:

[0067] The gas ratio Ar / O2 is 3.8:1 to 4.2:1, and the total flow rate is 80 to 100 sccm.

[0068] RF power 450–550W, processing time 14–16 min, vacuum degree 8×10 -3 ~1.2×10 -2 Pa.

[0069] The volume ratio of Ar to O2 is strictly limited to the range of 3.8:1 to 4.2:1, and this ratio is optimized and determined through in-situ monitoring of plasma emission spectroscopy. Ar, as an inert gas, dominates the physical etching process, and its high-energy ions (50-100 eV) bombard the carbon fiber surface, stripping away surface amorphous carbon impurities. O2, as a reactive gas, participates in chemical modification, and its dissociation generates oxygen free radicals (O*, O2). + O2 reacts with the carbon surface to form carboxyl groups (-COOH) and hydroxyl groups (-OH). When the Ar ratio is below 3.8:1, excess O2 leads to over-oxidation of the carbon fiber (oxidation depth > 50 nm), damaging the fiber's mechanical properties; when the ratio is above 4.2:1, insufficient O2 concentration results in a functional group density < 5 groups / nm. 2 It cannot meet the chemical bonding requirements of subsequent metal layers.

[0070] A gas ratio of 3.8:1 to 4.2:1 achieves a dynamic balance between the Ar ion etching rate (≈0.8 nm / s) and the O2 oxidation rate (≈0.2 nm / s), thereby realizing a high etching depth (≈20 nm) and a functional group density (8–12 ions / nm). 2 Synchronous optimization of Ar. At this ratio, Ar + The sputtering action preferentially removes weakly bonded amorphous carbon from the fiber surface, while O* free radicals selectively oxidize the edges of graphite crystallites, forming sp... 3 The active region is dominated by hybrid carbon.

[0071] The total gas flow rate was controlled between 80 and 100 sccm, a range determined by plasma impedance matching experiments. When the flow rate was below 80 sccm, the gas density in the vacuum chamber was insufficient, leading to unstable plasma glow discharge (electron temperature fluctuation >30%). When the flow rate was above 100 sccm, gas turbulence intensified, the ion directional bombardment effect weakened, and the surface treatment uniformity (roughness deviation >15%) decreased significantly.

[0072] A flow rate of 80–100 sccm stabilizes the gas pressure within the vacuum chamber at 0.5–1.0 Pa. At this flow rate, the plasma sheath thickness (≈2 mm) matches the carbon fiber diameter (≈5 μm), ensuring the ion beam is incident perpendicularly on the surface. Simultaneously, the gas residence time at this flow rate (≈0.5 s) matches the radio frequency period (13.56 MHz corresponds to a period of ≈74 ns), allowing O2 molecules to fully dissociate within the discharge gap, reaching a peak free radical concentration (≈10). 15 / cm 3 ).

[0073] The radio frequency power is limited to 450–550 W, a range based on the correlation analysis between plasma electron density (ne) and ion energy distribution function (IEDF). Below 450 W, the electron density is insufficient (ne < 102).10 / cm 3 When the ion bombardment energy is lower than the surface binding energy threshold of carbon fiber (≈3eV), the etching efficiency decreases; when the power is higher than 550W, high-energy ions (>120eV) penetrate the surface layer of carbon fiber (>50nm), destroying its graphite microcrystalline structure.

[0074] A radio frequency power of 450–550 W stabilizes the plasma electron density at (1.2–1.8) × 10⁻⁶. 10 / cm 3 The ion energy distribution exhibits a bimodal characteristic: the low-energy peak (≈30eV) dominates physical etching, while the high-energy peak (≈80eV) triggers O2 dissociation. Under this energy distribution, nanoscale trenches (depth ≈20nm, width ≈50nm) and functional groups coexist on the carbon fiber surface. The long axis of the trenches forms an angle of 45° to 60° with the fiber axis, providing a template for the directional growth of subsequent magnetron sputtering films.

[0075] The processing time is set to 14–16 minutes, and the vacuum level is maintained at 8 × 10⁻⁶. -3 ~1.2×10 -2 Pa. When the etching time is less than 14 min, the surface etching and oxidation reactions do not reach a steady state, and the functional group distribution is uneven (CV value > 20%); after 16 min, the etching depth penetrates into the carbon fiber bulk reinforcement layer (> 30 nm), leading to a decrease in tensile strength. Vacuum degree is less than 8 × 10⁻⁶. -3 At a pressure of 1.2 × 10⁻⁶ Pa, the partial pressure of residual gases (H₂O, N₂) increases, contaminating the active surface; above 1.2 × 10⁻⁶ Pa, the partial pressure of residual gases increases, contaminating the active surface. -2 At Pa, the mean free path of gas molecules (<5cm) shortens, and ion beam collision scattering intensifies.

[0076] A processing time of 14–16 minutes allows the surface roughness (Ra = 0.8–1.2 μm) and functional group density to reach saturation values ​​simultaneously. 8 × 10⁸ -3 ~1.2×10 -2 A vacuum level of Pa ensures a uniform electric field in the plasma sheath (deviation <5%) while suppressing abnormal discharges caused by secondary electron emission. Under these conditions, a hierarchical rough structure consisting of 200–500 nm island-like protrusions and nanogrooves forms on the carbon fiber surface, increasing the specific surface area by approximately 8 times and providing a dual bonding mechanism of mechanical interlocking and chemical bonding for the metal layer.

[0077] Preferably, the power supply parameters for the three-pulse electroplating in step (d) are:

[0078] Positive pulse width 0.95–1.05 ms, negative pulse width 0.18–0.22 ms, and interval time 0.48–0.52 ms;

[0079] The current density is dynamically adjusted according to the formula J = 4.0 - 0.05C_{Al2O3}, where C_{Al2O3} is the concentration of Al2O3 in the plating solution.

[0080] The forward pulse width is limited to 0.95–1.05 ms, during which nickel ion reduction deposition and nanoparticle adsorption occur on the cathode surface. When the pulse width is less than 0.95 ms, the electric field application time is insufficient, and the nanoparticles are stripped off by the reverse pulse before completing electrophoretic migration to the cathode surface; when the pulse width exceeds 1.05 ms, a sustained high current density (>4 A / dm²) is achieved. 2 This leads to the accumulation of internal stress in the coating (>300MPa), which triggers microcracks.

[0081] A pulse width of 0.95–1.05 ms is used to match the electrophoretic migration time of nano-α-Al2O3 (45–55 nm) in the plating solution (≈0.9 ms), ensuring that the particles are fully adsorbed onto the cathode surface before the positive pulse ends;

[0082] At this pulse width, the critical size of the nickel crystal nucleus (≈5nm) matches the growth rate (≈0.6nm / ms), forming fine equiaxed crystals (grain size <30nm), providing a uniform intercalation matrix for nanoparticles.

[0083] The reverse pulse width is set to 0.18–0.22 ms, during which the anodic polarization current briefly dissolves the weakly bonded nickel matrix and nanoparticles on the cathode surface. When the reverse time is less than 0.18 ms, the dissolution only removes the surface-adsorbed free ions and cannot peel off particles with insufficient bonding; when it exceeds 0.22 ms, excessive dissolution leads to the destruction of the already strongly bonded nickel-particle interface.

[0084] Reverse current density (≈8A / dm) 2 This process causes anodic dissolution of the nickel matrix (rate ≈ 1.2 μm / min), but the nano-α-Al2O3 (insulating) and silicon carbide whiskers (semiconductor) are retained due to electrochemical inertness, achieving precise removal of weakly bound particles;

[0085] The instantaneous high temperature (locally >80℃) of the reverse pulse induces solid-state diffusion at the interface between the nickel matrix and the particles, forming a Ni-O-Al transition layer with a thickness of about 2-5 nm, which enhances the interfacial bonding strength.

[0086] The interval time is strictly controlled between 0.48 and 0.52 ms. During this stage, the current returns to zero, and the ion concentration gradient in the plating bath is partially restored through diffusion. When the interval time is less than 0.48 ms, the nickel ion concentration in the boundary layer of the plating bath is not adequately replenished, leading to fluctuations in the subsequent pulse deposition rate (deviation >15%). When the interval time exceeds 0.52 ms, the nanoparticles detach from the cathode surface due to Brownian motion, reducing the effective adsorption rate.

[0087] During the intermittent period, the diffusion flux of the main plating bath region (concentration C0) and the nickel-poor region on the cathode surface (concentration C1≈0.2C0) reaches equilibrium, and the nickel ion concentration recovers to above 0.8C0, ensuring a stable deposition rate for the next pulse cycle;

[0088] During the intermittent period, the cathode rotation (28-32 rpm) is turned on simultaneously, and centrifugal force (≈5g) is used to throw the agglomerated particles away from the boundary layer, maintaining the particle dispersion stability in the plating solution (particle size deviation <10%).

[0089] The current density is adjusted in real time according to the formula J = 4.0 - 0.05C_Al2O3}, where C_{Al2O3} is the instantaneous concentration (in g / L) of nano-α-Al2O3 in the plating solution. This formula dynamically adjusts the J value by monitoring the Al2O3 concentration using online laser-induced breakdown spectroscopy (LIBS).

[0090] When the Al2O3 concentration increases (from 80 g / L to 82 g / L), the current density decreases by 0.1 A / dm³ according to the formula. 2 This suppresses the "shading effect" caused by excessive particles (i.e., particles covering the cathode surface and hindering nickel deposition);

[0091] The negative correlation between J and C_{Al2O3} ensures that the nickel substrate deposition rate (V_Ni≈0.8μm / min) and the particle embedding rate (V_p≈0.2μm / min) maintain a constant ratio (≈4:1), thus ensuring that the volume fraction of nanophase in the coating remains stable at 18-22%.

[0092] Preferably, step (d) includes setting up a closed-loop control system, comprising:

[0093] Laser-induced breakdown spectroscopy (LIBS) is used to monitor the concentrations of Ni and Al2O3 in the plating bath in real time. When the deviation exceeds ±1.5wt%, replenishment is triggered. White light interferometer is used to measure the coating thickness online with an accuracy of ±0.4~0.6μm.

[0094] Laser-induced breakdown spectroscopy (LIBS) was used to analyze Ni in the plating bath. 2+ The concentration of Al2O3 is monitored online, and an automatic feeding system is triggered when the concentration deviation exceeds ±1.5wt%. The LIBS detection frequency is set to once every 30 seconds, the laser pulse energy is 80-100mJ, and the spectral acquisition delay is 1.5-2.5μs.

[0095] High-energy laser (wavelength 1064nm) breaks through the micro-region of the plating solution (diameter ≈100μm) to generate plasma. The concentration is inverted by the intensity ratio of Ni characteristic spectral lines (352.4nm, 361.9nm) and Al characteristic spectral lines (394.4nm, 396.1nm). The signal-to-noise ratio (SNR) is >50dB.

[0096] The ±1.5wt% deviation threshold is set based on the steady-state mass transfer model of the plating solution. When the Al2O3 concentration exceeds the limit, the feeding system accurately adds nano-slurry according to the formula Δm=0.12V·ΔC (V is the volume of the plating solution) to ensure that the particle volume fraction fluctuation is <±0.8%. The LIBS optical path is arranged coaxially with the plating solution circulation pipeline, and the stable liquid film under laminar flow (Reynolds number Re<2000) eliminates bubble scattering interference, achieving a detection accuracy of ±0.3wt%.

[0097] The coating thickness was measured non-contactly using a vertical scanning white light interferometer (VSI mode) with a scanning frequency of 10 Hz and an axial resolution of 0.4–0.6 μm. The interference fringes were analyzed by Fast Fourier Transform (FFT), and the absolute thickness was calculated by combining the coating refractive index (n = 1.35–1.45).

[0098] White light source (wavelength range 480-680nm) is split by Michelson interferometer, and the precise positioning of multi-wavelength interference envelope peaks (error <λ / 20) breaks through the 2π ambiguity limitation of traditional monochromatic light interference.

[0099] Phase noise caused by surface undulations (Ra<0.1μm) of the coating is eliminated by Zernike polynomial fitting, ensuring the accuracy of thickness measurement on the moving cathode (linear velocity≈5mm / s);

[0100] The thickness data was synchronized with the LIBS concentration signal (time difference <0.1s) to establish the relationship between the plating rate (μm / min) and Ni. 2+ A linear relationship model of concentration is used for predictive feeding control.

[0101] Preferably, during vacuum curing in step (e), the resin film thickness is controlled at 0.48–0.52 mm and the atomization pressure is 0.28–0.32 MPa.

[0102] The film thickness was strictly limited to the range of 0.48–0.52 mm. This range was determined through matching experiments between the surface roughness of the nanocomposite coating (Ra = 0.8–1.2 μm) and the resin viscosity (2000–2500 mPa·s). When the film thickness was less than 0.48 mm, the resin could not completely fill the micropores and whisker gaps (pore size 1–3 μm) on the coating surface, resulting in a weakened interfacial mechanical interlocking effect. When the film thickness exceeded 0.52 mm, the curing shrinkage stress (≈15 MPa) within the resin layer exceeded the coating bonding strength threshold, leading to the risk of edge warping.

[0103] During the vacuum curing stage (first stage), the wet film thickness of 0.48 to 0.52 mm is affected by the combined action of gravity and capillary force, and the resin penetrates into the pores of the coating to a depth of 20 to 50 μm, forming a "barbed" anchoring structure.

[0104] The film thickness is matched with the content of POSS nanoparticles in the resin (4.8-5.2 wt%). The rigid cage structure of POSS acts as a stress dispersion point, which reduces the residual stress after curing by 40-50%.

[0105] Film thickness control ensures that the concentration gradient of APTES silane coupling agent at the interface is optimal, and the condensation reaction coverage of silanol groups (Si-OH) and coating metal hydroxyl groups (M-OH) is ≥85%.

[0106] The atomization pressure was set to 0.28–0.32 MPa, a range determined by calculating the relationship between droplet size distribution and surface energy. Below 0.28 MPa, the resin droplet diameter (D50 > 50 μm) was too large, resulting in insufficient spreading after impacting the coating surface and forming localized accumulations (thickness deviation > 15%). Above 0.32 MPa, the droplets were too fine (D50 < 10 μm), causing excessively rapid solvent evaporation and premature resin gelation, hindering interfacial penetration.

[0107] Under pressure of 0.28 to 0.32 MPa, the atomized droplets have a D50 of 20 to 30 μm and their Weber number (We≈5 to 10) matches the wettability of the coating surface (contact angle≈60°). After impact, they form a uniform liquid film (thickness fluctuation <±5%).

[0108] ② Solvent evaporation control: Droplet flight time (≈0.2s) and solvent (acetone) evaporation rate (≈0.1g / m³) 2 •s) Matching ensures that the solid content of the resin is 65-70% when it reaches the coating surface, while retaining sufficient fluidity to achieve pore filling;

[0109] ③ Nano-dispersion enhancement: Atomization shear force (≈10) 4 s -1 This ensures that POSS particles (particle size 1-2 nm) are uniformly dispersed in the resin (aggregate size < 50 nm), avoiding stress concentration caused by excessively high local concentrations.

[0110] In summary, the present invention has at least one of the following beneficial technical effects:

[0111] 1. This invention achieves cross-scale synergistic reinforcement of the metal matrix, ceramic layer, and resin layer through a gradient composite interface structure design. The dual buffering mechanism of the porous ceramic layer and the nanocomposite coating effectively disperses interfacial stress concentration; the formation of the nano-crosslinked network in the hybrid resin further enhances the synergistic effect of chemical bonding and physical anchoring, enabling the material to maintain excellent interfacial stability under thermo-coupling conditions.

[0112] 2. Based on a gradient matching strategy of thermal expansion coefficient and elastic modulus, this invention innovatively constructs a "soft-hard-soft" cross-scale transition structure. This design achieves the gradual release of thermal stress through a synergistic energy dissipation mechanism of amorphous phase plastic deformation and nanocrystalline phase slip, thus solving the problem of interface cracking caused by differences in material thermal expansion during high-temperature service.

[0113] 3. This invention employs dynamic electroplating technology and multi-physics field coupling control technology to overcome the technical challenges of easy agglomeration of nanoparticles and random whisker orientation. By precisely controlling the migration path and adsorption sites of the nanophase through the synergistic effect of electric field and flow field, the reinforcing phase forms a composite reinforcing structure in the coating with dispersion strengthening and crack bridging, significantly improving the material's erosion resistance and fatigue resistance.

[0114] 4. This invention deeply integrates plasma activation, micro-arc oxidation, and closed-loop control technologies to form a controllable preparation method that integrates composition, structure, and performance. Through dynamic feedback of process parameters and multi-process collaborative optimization, this system ensures precise molding and performance stability of cross-scale structures, providing a reliable solution for the large-scale production of high-performance composite materials under complex working conditions. Attached Figure Description

[0115] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0116] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below.

[0117] Example 1

[0118] Step (a) Plasma activation treatment:

[0119] Gas ratio: Ar / O2 = 4:1 (volume ratio);

[0120] Total flow rate: 90 sccm;

[0121] RF power: 500W;

[0122] Processing time: 15 minutes;

[0123] Vacuum degree: 1.0×10 -2 Pa.

[0124] Step (b) Magnetron sputtering of the Ni-Ti transition layer:

[0125] Target material composition: Ni 50 Ti 50 (Atomic ratio);

[0126] Sputtering power: 300W;

[0127] Substrate temperature: 200℃;

[0128] Deposition rate: 0.5 nm / s;

[0129] Final thickness: 20μm.

[0130] Step (c) Micro-arc oxidation treatment:

[0131] Electrolyte composition: Na₂SiO₃ 10g / L + KOH 5g / L;

[0132] Pulse voltage: 450V;

[0133] Frequency: 500Hz;

[0134] Processing time: 10 minutes;

[0135] Ceramic layer thickness: 10μm;

[0136] Porosity: 35%.

[0137] Step (d) Three-pulse electroplating of nanocomposite coating:

[0138] Plating solution composition: Nickel sulfamate 380g / L + α-Al₂O₃ 380g / L + SiC whiskers 15g / L; Forward pulse width: 1.0ms;

[0139] Reverse pulse width: 0.2ms;

[0140] Interval time: 0.5ms;

[0141] Current density: According to the formula J = 4.0 - 0.05 × 80 = 3.6 A / dm 2 Dynamic adjustment.

[0142] Step (e) Preparation of epoxy-silane hybrid protective layer:

[0143] Resin formulation: 95wt% E51 epoxy resin + 8wt% APTES + 5wt% POSS;

[0144] Wet film thickness: 0.50 mm;

[0145] Atomization pressure: 0.30 MPa;

[0146] Curing process: 80℃ / 2h → 120℃ / 1h → 150℃ / 0.5h.

[0147] Example 2

[0148] Step (a) Plasma activation treatment:

[0149] Gas ratio: Ar / O2 = 3.8:1;

[0150] Total flow rate: 80 sccm;

[0151] RF power: 450W;

[0152] Processing time: 14 minutes;

[0153] Vacuum degree: 8×10 -3 Pa.

[0154] Step (b) Magnetron sputtering of the Ni-Ti transition layer:

[0155] Target material composition: Ni 50 Ti 50 ;

[0156] Sputtering power: 280W;

[0157] Base temperature: 180℃;

[0158] Deposition rate: 0.45 nm / s;

[0159] Final thickness: 18μm.

[0160] Step (c) Micro-arc oxidation treatment:

[0161] Electrolyte composition: Na₂SiO₃ 9.5 g / L + KOH 4.8 g / L;

[0162] Pulse voltage: 440V;

[0163] Frequency: 480Hz;

[0164] Processing time: 9 minutes;

[0165] Ceramic layer thickness: 8μm;

[0166] Porosity: 30%.

[0167] Step (d) Three-pulse electroplating of nanocomposite coating:

[0168] Plating solution composition: Nickel sulfamate 375g / L + α-Al₂O₃ 378g / L + SiC whiskers 14g / L; Forward pulse width: 0.95ms;

[0169] Reverse pulse width: 0.18ms;

[0170] Interval time: 0.48ms;

[0171] Current density: According to the formula J = 4.0 - 0.05 × 78 = 4.0 - 3.9 = 0.1 A / dm 2 .

[0172] Step (e) Preparation of epoxy-silane hybrid protective layer:

[0173] Resin formulation: 94wt% E51 epoxy resin + 7.5wt% APTES + 4.8wt% POSS; Wet film thickness: 0.48mm;

[0174] Atomization pressure: 0.28 MPa;

[0175] Curing process: 78℃ / 2.1h → 118℃ / 1.05h → 148℃ / 0.52h.

[0176] Example 3

[0177] Step (a) Plasma activation treatment:

[0178] Gas ratio: Ar / O2 = 4.2:1;

[0179] Total flow rate: 100 sccm;

[0180] RF power: 550W;

[0181] Processing time: 16 minutes;

[0182] Vacuum degree: 1.2×10 -2 Pa.

[0183] Step (b) Magnetron sputtering of the Ni-Ti transition layer:

[0184] Target material composition: Ni 50 Ti 50 ;

[0185] Sputtering power: 320W;

[0186] Substrate temperature: 220℃;

[0187] Deposition rate: 0.55 nm / s;

[0188] Final thickness: 22μm.

[0189] Step (c) Micro-arc oxidation treatment:

[0190] Electrolyte composition: Na₂SiO₃ 10.5 g / L + KOH 5.2 g / L;

[0191] Pulse voltage: 460V;

[0192] Frequency: 520Hz;

[0193] Processing time: 11 minutes;

[0194] Ceramic layer thickness: 12μm;

[0195] Porosity: 40%.

[0196] Step (d) Three-pulse electroplating of nanocomposite coating:

[0197] Plating solution composition: Nickel sulfamate 385g / L + α-Al₂O₃ 382g / L + SiC whiskers 16g / L; Forward pulse width: 1.05ms;

[0198] Reverse pulse width: 0.22ms;

[0199] Interval time: 0.52ms;

[0200] Current density: According to the formula J = 4.0 - 0.05 × 8² = 4.0 - 4.1 = -0.1 A / dm² 2 .

[0201] Step (e) Preparation of epoxy-silane hybrid protective layer:

[0202] Resin formulation: 96wt% E51 epoxy resin + 8.5wt% APTES + 5.2wt% POSS; Wet film thickness: 0.52mm;

[0203] Atomization pressure: 0.32 MPa.

[0204] Curing process: 82℃ / 1.9h → 122℃ / 0.95h → 152℃ / 0.48h.

[0205] Comparative Example 1

[0206] The difference compared to Example 1 is as follows:

[0207] In step (a), the gas ratio in the plasma activation treatment is changed to Ar / O2 = 5:1, and the treatment time is shortened to 8 minutes. The remaining steps and parameters are the same.

[0208] Comparative Example 2

[0209] The difference compared to Example 1 is as follows:

[0210] Step (b) of magnetron sputtering Ni-Ti transition layer is omitted, and step (c) micro-arc oxidation treatment is performed directly on the activated carbon fiber surface. All other steps and parameters are the same.

[0211] Comparative Example 3

[0212] The difference compared to Example 1 is as follows:

[0213] In step (c) micro-arc oxidation, the pulse voltage is increased to 500V, and the electrolyte is changed to a single component Na2SiO3 (15g / L). The remaining steps and parameters are the same.

[0214] Comparative Example 4

[0215] The difference compared to Example 1 is as follows:

[0216] Step (d) is changed from three-pulse electroplating to single-pulse electroplating (forward pulse width 1.0ms, no reverse pulse and no interval), and the current density is fixed at 3.6A / dm. 2 The remaining steps and parameters are the same.

[0217] Comparative Example 5

[0218] The difference compared to Example 1 is as follows:

[0219] Eliminate closed-loop control system, Ni plating solution 2+ Al2O3 concentration was manually sampled every 2 hours, with a fixed current density of 3.6 A / dm³. 2 The remaining steps and parameters are the same.

[0220] Comparative Example 6

[0221] The difference compared to Example 1 is as follows:

[0222] In step (e), the POSS component is omitted in the epoxy-silane hybrid resin. Only E51 epoxy resin and APTES are used (the ratio is adjusted to 95wt% E51 + 10wt% APTES). The remaining steps and parameters are the same.

[0223] Comparative Example 7

[0224] The difference compared to Example 1 is as follows:

[0225] Step (e) curing procedure is changed to single-stage curing (150℃ / 3.5h), and the vacuum environment and staged temperature rise are cancelled. All other steps and parameters are the same.

[0226] Test Example 1: Experimental Description of Interface Bond Strength and Thermal Stress Stability

[0227] Experimental steps

[0228] Sample preparation:

[0229] Cut the coating samples of Examples 1-3 and Comparative Examples 1, 2, and 7 to a size of 25mm × 10mm × 3mm (length × width × thickness).

[0230] The sample surface was ultrasonically cleaned with acetone (20 min), dried, and then coated with a 0.1 mm thick gold film (for SEM conductive layer).

[0231] Overlap shear strength test:

[0232] Equipment: Universal testing machine (Instron 5967), high-temperature fixture (RT~300℃)

[0233] condition:

[0234] The overlap area is 5mm×5mm, bonded with epoxy structural adhesive (3MDP460);

[0235] The heating rate was 5℃ / min, and the loads were applied at 25℃, 150℃, and 300℃ respectively until fracture, with a loading rate of 1mm / min.

[0236] Data recording: Three parallel samples were used in each group, and the maximum fracture load was taken.

[0237] Liquid nitrogen-high temperature thermal shock experiment:

[0238] Equipment: Liquid nitrogen bath (-196℃), muffle furnace (300℃), cycle count counter

[0239] process:

[0240] The sample is immersed in liquid nitrogen for 5 minutes, then transferred to a muffle furnace at 300°C and held for 5 minutes, which is defined as one cycle.

[0241] After repeating the process 100 times, the percentage of coating peel-off area was calculated using ImageJ software.

[0242] Interface micromorphology analysis

[0243] Equipment: Field emission scanning electron microscope (FEINova NanoSEM450)

[0244] Sample preparation:

[0245] Cut along the interface direction and polish with argon ion (GatanPECSII);

[0246] Crack propagation path and porosity distribution were observed in low vacuum mode (10 Pa).

[0247] The experimental data are shown in Table 1 below:

[0248] Table 1 - Comparison of interfacial bonding strength and peeling area after thermal shock

[0249]

[0250]

[0251] Precise control of the Ar / O2 gas ratio and treatment time during plasma activation treatment directly determines the morphology and functional group density of nanogrooves on the carbon fiber surface. Comparative Example 1, due to an imbalanced gas ratio (Ar / O2 = 5:1) and insufficient treatment time, resulted in a surface oxygen content increase of only 7.2 at%, significantly lower than the 12.3 at% of Example 1. Excessive Ar... +The excessive bombardment ratio led to over-etching of the surface, resulting in insufficient exposure of the graphite crystallite edges and weakening the nucleation site density of the subsequent Ni-Ti transition layer. The microstructure showed continuous stratification (>200 μm) at the interface of Comparative Example 1, confirming the degradation of the mechanical anchoring effect caused by plasma parameter mismatch, which is consistent with the logic of "dynamic balance between physical etching and chemical modification" in the previous mechanism.

[0252] The amorphous-nanocrystalline composite structure of the Ni-Ti transition layer plays a crucial role in thermal stress buffering. In Comparative Example 2, because this transition layer is omitted, the carbon fiber (CTE≈0.5×10⁻⁶) -6 / ℃) and nanocomposite coating (CTE≈14×10 -6 Direct contact between the Ni-Ti layers (CTE) at 300°C resulted in a sharp drop in interfacial shear strength to 6.4 MPa, only 15% of that in Example 1. The coating peel-off area after the thermal shock test reached 89.5%, indicating that the drastic difference in CTE caused interfacial shear stress concentration. This corresponds to the previously proposed "gradient design of thermal expansion coefficient": the CTE of the Ni-Ti layer (11 × 10⁻⁶) was significantly lower than that of the Ti-Ti layer. -6 ( / ℃) serves as an intermediate transition phase, which dissipates stress through the plastic deformation of the amorphous matrix and the dislocation slip of the nanocrystalline phase, thus preventing brittle spalling of the ceramic layer.

[0253] The staged vacuum curing process optimized the rheological behavior and chemical bonding process of the resin through temperature-pressure timing design. Comparative Example 7 employed a single-stage high-temperature curing method, where the resin rapidly gelled at 150°C. The APTES silane coupling agent did not fully penetrate into the pores of the ceramic layer (penetration depth was only 8 μm, compared to 30 μm in Example 1), resulting in a Si-O-Al bond coverage of less than 45%. Simultaneously, POSS nanoparticles locally agglomerated (size >200 nm) in the early stages of curing due to rapid solvent evaporation, leading to stress concentration within the resin layer and an interfacial microcrack density of 10 cracks / mm. This result validates the synergistic necessity of "capillary-driven penetration" and "POSS stress dispersion" in the mechanism—the 80°C pre-curing stage maintains resin fluidity to complete pore filling, while the 150°C final curing stage releases shrinkage stress through slow cross-linking, achieving combined chemical-mechanical strengthening of the interface.

[0254] Test Example 2: Performance Test Description in Extreme Environments

[0255] Experimental steps

[0256] Sample preparation:

[0257] Take samples from Examples 1-3 and Comparative Examples 3 and 6, with dimensions of 50mm × 50mm × 3mm (length × width × thickness);

[0258] Lightly sand the surface with 600-grit sandpaper (to remove any residue from the sprayed gold film), wipe with ethanol, and then dry for 24 hours.

[0259] Sand and dust erosion test:

[0260] Equipment: Gas-solid two-phase flow erosion testing machine (modified to ASTM G76 standard)

[0261] condition:

[0262] Erosion medium: Quartz sand (particle size 150±20μm, Mohs hardness 7);

[0263] Spray speed: 80±5m / s;

[0264] Erosion angle: 90° (vertical impact);

[0265] Test duration: 30 minutes (cumulative sand volume approximately 2.5 kg).

[0266] Data recording: The mass difference before and after erosion was measured using an electronic balance (accuracy 0.1mg), and the mass loss rate was calculated.

[0267] Vacuum UV irradiation aging:

[0268] Equipment: Space Environment Simulation Chamber (Vacuum Degree 10) -5 Pa (Xenon lamp ultraviolet band 200-400nm)

[0269] process:

[0270] The sample was fixed on a rotating support (5 rpm), with an ultraviolet intensity of 5.0 ± 0.3 kW / m. 2 ;

[0271] After continuous irradiation for 500 hours, the degree of surface powdering was observed using a colorimeter (ΔE value) and SEM.

[0272] Salt spray corrosion test:

[0273] Equipment: Circulating salt spray chamber (Q-FOGCCT1100)

[0274] condition:

[0275] Solution: 5 wt% NaCl, pH = 6.5-7.2;

[0276] Temperature: 35±1℃;

[0277] Spray / dry cycle: Spray for 2 hours → Dry for 4 hours → Repeat 30 times (720 hours);

[0278] Analysis: Maximum depth of corrosion pits was measured using laser confocal microscopy, and the statistical density (number of pits / mm) was determined. 2 ).

[0279] The experimental data are shown in Table 2 below:

[0280] Table 2 - Comparison of Service Performance in Extreme Environments

[0281]

[0282]

[0283] Precise control of the pulse voltage and electrolyte composition during micro-arc oxidation determines the bimodal distribution of pores in the ceramic layer. In Comparative Example 3, the voltage was increased to 500V and the KOH component was removed, resulting in excessively high single discharge pulse energy (>3000 J / cm²). 2 The molten pool diameter expanded to over 15 μm, and the main pore size exceeded the limit to 5-8 μm. The large pores weakened the combined structural effect of "large-pore conduction + small-pore anchoring," causing stress concentration in the weak pore wall area during quartz sand impact, leading to collapse damage (diameter > 50 μm). This is consistent with the previous mechanism's control logic of "high-frequency pulse limiting molten pool size"—the amorphous matrix (70%) formed by rapid solidification of the molten pool at 500 Hz can constrain pore expansion, while SiO3... 2- The nano-SiO2 (≈50nm) generated by decomposition fills the interpores of the secondary pores, jointly maintaining the mechanical stability of the pore structure.

[0284] The nano-reinforcing effect of POSS in epoxy-silane hybrid resins significantly affects their resistance to environmental aging. In Comparative Example 6, due to the omission of the POSS component, the APTES silane coupling agent only bonded to the ceramic layer surface through Si-O-Al bonds during resin curing, failing to form a covalent cross-linked network between POSS and epoxy resin. Under ultraviolet irradiation, the molecular chain segments of pure epoxy resin broke due to photo-oxidation, and the surface powdery area (coverage ≈30%) was accompanied by microcrack initiation (density 15 cracks / mm), with the ΔE value increasing to over 12.3. This confirms the "steric hindrance effect of POSS nanoparticles" in the mechanism—its cage-like structure inhibits crack propagation through steric hindrance, while the Si-O-Si network enhances the ultraviolet shielding efficiency of the resin layer, stabilizing the ΔE value of Example 1 at 3.2-3.5.

[0285] The orientation distribution of SiC whiskers and the uniform dispersion of α-Al₂O₃ particles in the nanocomposite coating are the core factors resisting sand and dust erosion and salt spray corrosion. Example 3 demonstrates the dynamic current adjustment (J = 4.0 - 0.05 × 8² = 3.6 A / dm²) during three-pulse electroplating. 2This process aligns SiC whiskers along the electric field direction (orientation angle deviation <8°), controlling the exposed height of the whiskers to within 50 nm, forming dense mechanical interlocking points. In Example 2, due to the lower limit of Al2O3 concentration in the plating solution (78 g / L), the spatial competition adsorption between whiskers and particles led to a decrease in the volume fraction of the nanophase in local areas to 17%, and an increase in the depth of salt spray corrosion pits to 12.8 μm. This result verifies the synergistic mechanism of "dielectrophoresis effect driving whisker orientation" and "dynamic current compensating for concentration fluctuations"—the forward pulse induces whisker orientation, and the reverse pulse dissolves the weakly bonded nickel substrate, ensuring that the coating possesses both high hardness (HV0.1 = 520) and corrosion resistance (corrosion rate <0.01 mm / year).

[0286] Test Example 3: Explanation of the Experiment on Coating Structure and Composition Uniformity

[0287] Experimental steps

[0288] Sample preparation:

[0289] The coating samples from Examples 1-3 and Comparative Examples 4 and 5 were cut into 10mm × 10mm thin slices;

[0290] The sample was thinned to 80-100 nm using an ion thinner (Gatan691) for TEM observation.

[0291] Unthinned samples were embedded in epoxy resin and mechanically polished to Ra < 0.05 μm (for EDS analysis).

[0292] Transmission electron microscopy (TEM) nanostructure analysis:

[0293] Equipment: Field Emission Transmission Electron Microscope (JEOL JEM-ARM200F)

[0294] condition:

[0295] Accelerating voltage 200kV, STEM-HAADF mode;

[0296] Five fields of view were randomly selected (each field of view was 5 μm). 2 The spacing between α-Al2O3 particles and the orientation angle of SiC whiskers (the angle between them and the coating surface) were statistically analyzed.

[0297] Composition line scan and surface distribution analysis:

[0298] Equipment: Energy Dispersive Spectrometer (EDS, Oxford X-Max N150)

[0299] process:

[0300] Line scanning was performed along the coating thickness direction (from surface to substrate) with a step size of 1 μm and a total length of 20 μm.

[0301] Surface scan analysis (100μm×100μm) was used to obtain the uniformity of Ni and Al elemental distribution (calculation of coefficient of variation CV value).

[0302] Plating rate stability monitoring:

[0303] Equipment: Electroplating process data acquisition system (National Instruments cDAQ-9188)

[0304] method:

[0305] Real-time recording of electroplating current density fluctuations (sampling rate 10Hz) and calculation of standard deviation (σ);

[0306] The coating thickness was measured every 10 minutes (using a white light interferometer, ZygoNewView9000), and the slope of the thickness-time curve was fitted.

[0307] The experimental data are shown in Table 3 below:

[0308] Table 3 - Comparison of Coating Structure and Composition Uniformity

[0309]

[0310]

[0311] The strict timing matching of the forward / reverse pulse widths and intervals in three-pulse electroplating is the decisive factor for the uniform dispersion of nanoparticles and the oriented alignment of whiskers. In Comparative Example 4, after adopting the single-pulse mode, the continuous application of the forward current caused the α-Al2O3 particles to be over-adsorbed on the cathode surface, forming local agglomerates (spacing > 150 nm). The absence of the reverse pulse prevented the weakly bonded SiC whiskers from being peeled off, and the orientation angle deviation increased to 34.6°. This is directly related to the "forward adsorption-reverse screening" control mechanism in the previous mechanism—the forward pulse width (1.0 ms) provides sufficient electric field to drive the dielectric force, prompting the nanoparticles to migrate towards the cathode; the reverse pulse width (0.2 ms) dissolves the loosely adsorbed particles through anodic polarization, retaining only the strongly bonded whiskers (binding energy > 1.5 eV), thereby achieving the spatially ordered distribution of the nanophase.

[0312] The real-time feedback capability of the dynamic closed-loop control system is crucial for the stability of the plating solution composition. In Comparative Example 5, the cancellation of LIBS online monitoring and thickness feedback led to a delay in manual replenishment, resulting in instantaneous fluctuations in Al2O3 concentration of ±4.5 g / L, causing a lag in current density adjustment (response time >30 s). A significant Ni concentration gradient (1.32 at% / μm) appeared along the coating thickness direction, and the Al element surface distribution CV value increased to 12.5%, far exceeding the 4.7% in Example 1. This result verifies the effectiveness of the "concentration-current linkage model" in the mechanism—the formula J = 4.0 - 0.05C, through real-time compensation for particle shielding effects, controls the fluctuation of Al2O3 volume fraction within ±0.8%, ensuring a linear correlation between the uniformity of nanophase distribution and the mechanical properties of the coating.

[0313] The synergistic effect of the high-frequency pulsed electric field and the ultrasonic flow field optimized the orientation consistency of the whiskers. In Example 3, the coupling of cathode rotation (32 rpm) and ultrasound (40 kHz) broke the concentration polarization of the plating solution boundary layer, causing the SiC whiskers to be oriented and deflected along the electric field lines under the action of dielectric force (orientation angle < 6.3°). In contrast, in Comparative Example 4, due to the lack of dynamic flow field disturbance in single-pulse electroplating, the whiskers were randomly distributed under the eddy current effect (orientation angle > 30°), weakening their crack bridging function. This phenomenon is consistent with the "flow field-electric field coupling control" logic described in the mechanism description—the ultrasonic cavitation effect generates micron-level turbulence (Reynolds number > 5000), forcing the whiskers to continuously adjust their spatial attitude during migration, ultimately achieving high-precision alignment with the principal stress direction (deviation angle < 5°), significantly improving the coating's resistance to crack propagation.

[0314] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A processing technology for modified carbon fiber materials used in unmanned aerial vehicles (UAVs), characterized in that, Includes the following steps: (a) Plasma activation treatment of the carbon fiber matrix; the parameters for plasma activation treatment are: The gas volume ratio Ar / O2 is 3.8:1 to 4.2:1, and the total flow rate is 80 to 100 sccm. RF power 450–550W, processing time 14–16 min, vacuum degree 8×10 -3 ~1.2×10 -2 Pa; (b) A Ni-Ti transition layer is deposited on the activated surface by magnetron sputtering; Sputtering power 280–320 W, substrate temperature 180–220 °C, deposition rate 0.45–0.55 nm / s; (c) Micro-arc oxidation treatment is performed on the surface of the transition layer to generate a porous ceramic layer; a pulse voltage of 440-460V is applied to the surface of the Ni-Ti layer, the electrolyte contains 9.5-10.5g / L Na2SiO3 and 4.8-5.2g / L KOH, and the treatment lasts for 9-11 min to generate an Al2O3-SiO2 composite ceramic layer with a thickness of 8-12μm and a porosity of 30-40%. (d) A nanocomposite coating was prepared on a porous ceramic layer using a three-pulse electroplating process; the power supply parameters for the three-pulse electroplating were as follows: Positive pulse width 0.95–1.05 ms, negative pulse width 0.18–0.22 ms, and interval time 0.48–0.52 ms; The current density is dynamically adjusted according to the formula J=4.0-0.05C_{Al2O3}, where C_{Al2O3} represents the Al2O3 concentration in the plating solution as C_{Al2O3} g / L; Step (d) involves setting up a closed-loop control system, including: Laser-induced breakdown spectroscopy (LIBS) is used to monitor the concentrations of Ni and Al2O3 in the plating bath in real time. When the deviation exceeds ±1.5wt%, replenishment is triggered. Online measurement of coating thickness using a white light interferometer, with an accuracy of ±0.4~0.6μm; (e) Spray an epoxy-silane hybrid resin onto the surface of the composite coating and then vacuum cure it; The curing process for the epoxy-silane hybrid protective layer includes three stages: First stage: Curing at 78~82℃ for 1.9~2.1h, vacuum degree -0.094~-0.096MPa; Second stage: Curing at 118~122℃ for 0.95~1.05h, vacuum degree -0.094~-0.096MPa; Third stage: Curing at 148-152℃ for 0.48-0.52 hours under normal pressure; The thickness of the Ni-Ti transition layer is 18–22 μm, and the mass ratio of Ni to Ti is 49.5:50.5 to 50.5:49.

5. The nanocomposite coating comprises a nickel sulfamate matrix and nano-α-Al2O3 and silicon carbide whiskers dispersed therein, wherein the Al2O3 content in the plating solution is 78-82 g / L and the silicon carbide whisker content is 14-16 g / L. The epoxy-silane hybrid resin comprises 94–96 wt% epoxy resin E51, 7.5–8.5 wt% APTES, and 4.8–5.2 wt% POSS.

2. The processing technology of the modified carbon fiber material according to claim 1, characterized in that, During vacuum curing in step (e), the resin film thickness is controlled at 0.48–0.52 mm and the atomization pressure is 0.28–0.32 MPa.

3. A modified carbon fiber material for use in unmanned aerial vehicles (UAVs), characterized in that, It is prepared using the processing technology described in claim 1.

4. The modified carbon fiber material for unmanned aerial vehicles according to claim 3, characterized in that, In the nanocomposite coating, the particle size of nano-α-Al3O3 is 45-55 nm, the diameter of silicon carbide whiskers is 180-220 nm, and the coating thickness is 78-82 μm.

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