Epoxy composite coating with directionally arranged modified Ti3C2Tx nanosheets and preparation method of epoxy composite coating
Modified Ti3C2Tx nanosheets were prepared by acid etching and ultrasonic treatment. By using γ-aminopropyltriethoxysilane modification combined with extrusion-shear stress method, the problems of easy oxidation, easy corrosion and unstable arrangement of Ti3C2Tx nanosheets in epoxy resin coating were solved, and high-efficiency anti-corrosion performance was achieved.
Patent Information
- Application Number
- CN202511555628.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-29
- Publication Date
- 2026-01-02
AI Technical Summary
In existing epoxy resin coatings, Ti3C2Tx nanosheets are easily oxidized, prone to galvanic corrosion, have unstable arrangement structures, and are not tightly bonded to the coating resin, making it difficult to achieve large-scale application. Furthermore, existing orientation methods are cumbersome and inefficient.
Ti3C2Tx nanosheets were prepared by acid etching and ultrasonic treatment. The Ti3C2Tx nanosheets were modified with γ-aminopropyltriethoxysilane and oriented by extrusion-shear stress method during coating curing, combined with epoxy resin crosslinking reaction.
The chemical stability and orientation of Ti3C2Tx nanosheets were improved, the interfacial voids were reduced, galvanic corrosion was suppressed, and a dense barrier layer was formed, thus achieving long-term corrosion protection.
Smart Images
Figure CN121249239A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of anti-corrosion coating material preparation technology, specifically relating to a modified Ti3C2T x An epoxy composite coating with oriented nanosheets and its preparation method. Background Technology
[0002] Epoxy resin coatings are widely used for corrosion protection of metallic materials due to their excellent adhesion, chemical resistance, and high surface hardness. However, during the curing process, submicron-sized channels inevitably form in the network structure of epoxy resin coatings. These channels provide diffusion pathways for corrosive media (such as water, oxygen, and chloride ions), severely weakening the barrier performance of the coating. In recent years, the introduction of two-dimensional nanomaterials (such as graphene, hexagonal boron nitride, layered double hydroxides, and Ti3C2T) into coatings has been a focus. x (etc.) have been proven to be effective ways to improve the barrier performance of coatings. Among them, the emerging two-dimensional transition metal carbide Ti3C2T x MXene shows great potential in enhancing the corrosion resistance of epoxy resin coatings due to its large specific surface area, excellent barrier properties, high conductivity, and higher mechanical strength compared to graphene.
[0003] However, Ti3C2T x The application of epoxy anti-corrosion coatings still faces many key challenges: (1) Ti3C2T x (1) It has insufficient chemical stability and is prone to oxidation and degradation when stored in humid air for a long time; (2) High conductivity Ti3C2T x It may form a corrosion couple with the metal substrate in the corrosive medium, which may accelerate the corrosion of the metal substrate; (3) Two-dimensional materials are often randomly oriented in the coating, which greatly weakens their barrier efficiency. Although researchers have tried to use layer-by-layer self-assembly, flow induction, electric field induction, magnetic field induction and other methods to promote the corrosion of two-dimensional materials (such as Ti3C2T) x While these methods align the nanosheets parallel to the substrate, they typically suffer from cumbersome operation, low efficiency, demanding equipment, and high costs, hindering large-scale application. More importantly, these alignment methods often employ non-contact induction, leaving interfacial voids between the nanosheets and the coating resin, making it difficult to further improve the coating's density. Furthermore, existing technologies often struggle to simultaneously address the Ti3C2T... x Nanosheets suffer from numerous problems, including easy oxidation, easy galvanic corrosion, unstable arrangement structure, and poor bonding with coating resin.
[0004] Therefore, it is necessary to develop a method that can synergistically improve Ti3C2T x The chemical stability and orientation of the nanosheets significantly reduce the interfacial voids between the nanosheets and the coating resin, effectively inhibiting Ti3C2Tx This method, which addresses the galvanic corrosion between the modified Ti3C2T and the metal substrate, is simple and suitable for large-scale applications, thus enabling the construction of modified Ti3C2T with long-lasting corrosion resistance. x The development of oriented epoxy composite coatings with nanosheets is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] This invention addresses the poor barrier properties of existing epoxy resin coatings and the need for embedded Ti3C2T. x To address the issue of nanosheets failing to fully realize their performance advantages, a modified Ti3C2T is proposed. x An epoxy composite coating with oriented nanosheets and its preparation method are disclosed. This method, through the synergistic effect of silane modification and stress-induced alignment, not only stabilizes the oriented structure of the nanosheets, enhancing the structural stability and density of the coating (crosslinking and curing under continuous extrusion pressure significantly reduces interfacial voids between the nanosheets and the coating resin), but also effectively severs the electrical connection channels between the nanosheets and the metal substrate, suppressing galvanic corrosion. Therefore, the resulting modified Ti3C2T... x The epoxy composite coating with oriented nanosheets exhibits superior long-lasting corrosion protection performance that far exceeds expectations.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: A modified Ti3C2T x The nanosheet-oriented epoxy composite coating is obtained by simply acid etching and ultrasonic treatment to exfoliate Ti3AlC2 into Ti3C2T. x Nanosheets; then using γ-aminopropyltriethoxysilane (APTES) to saturate Ti3C2T x Nanosheets were covalently grafted to prepare amino-rich modified Ti3C2T. x Nanosheets; then modified Ti3C2T x Nanosheets were incorporated into epoxy resin, and an extrusion-shear stress method was used during the coating curing process. This method involves continuously applying vertical pressure and converting the extrusion stress into shear stress parallel to the substrate to simultaneously induce the modification of Ti3C2T. x The oriented arrangement of nanosheets and the cross-linking reaction of epoxy resin involving amino groups on their surface lead to the preparation of modified Ti3C2T. x An epoxy composite coating with oriented nanosheets.
[0007] Specifically, the modified Ti3C2T x The preparation of an epoxy composite coating with oriented nanosheets includes the following steps: (1)Ti3C2T x Preparation of nanosheets: LiF was dissolved in 12 mol / L HCl solution, and Ti3AlC2 powder was added. The mixture was stirred in a water bath and then cooled to room temperature. The solution was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The supernatant was then sonicated in ice water under nitrogen protection. After centrifugation, the supernatant was collected and freeze-dried to obtain Ti3C2T. x Nanosheets; (2) Modified Ti3C2T x Preparation of nanosheets: γ-aminopropyltriethoxysilane was added to an ethanol / water mixture, and acetic acid solution was added to adjust the system to a weakly acidic state. The mixture was then magnetically stirred at room temperature for 6 hours, followed by the addition of the prepared Ti3C2T. x Nanosheets were ultrasonically treated for 30 min, and then ammonia solution was added dropwise to adjust the system to weakly alkaline. After stirring at 70 °C for 6 h, the mixture was centrifuged, washed, and freeze-dried to obtain modified Ti3C2T with an amino-rich surface. x Nanosheets; (3) Modified Ti3C2T x Preparation of oriented epoxy composite coatings with nanosheets: The prepared modified Ti3C2T x Nanosheets were ultrasonically dispersed in tetrahydrofuran, and epoxy resin E-44 and polyamide 650 curing agent were added. The mixture was stirred continuously until excess solvent was completely evaporated. Then, the prepared mixture was coated onto a steel plate using a coating rod with a thickness of 200 μm. A silicone pressure plate was immediately placed on top and vertical pressure was applied. After curing at 40°C for 48 hours, the silicone pressure plate was peeled off to obtain modified Ti3C2T. x An epoxy composite coating with oriented nanosheets.
[0008] Furthermore, the solid-liquid ratio of the LiF and HCl solutions used in step (1) is 1g:20mL.
[0009] Furthermore, the mass ratio of LiF and Ti3AlC2 powder used in step (1) is 1:1.
[0010] Furthermore, the temperature of the water bath stirring in step (1) is 35°C and the time is 24h.
[0011] Furthermore, the ultrasonic treatment in step (1) has a power of 350W and a duration of 1h.
[0012] Furthermore, in step (2), the volume ratio of ethanol to water in the ethanol / water mixed solution is 19:1.
[0013] Furthermore, the volume ratio of γ-aminopropyltriethoxysilane to the ethanol / water mixed solution used in step (2) is 1:20.
[0014] Furthermore, the Ti3C2T added in step (2) x The solid-liquid ratio of the nanosheets to the γ-aminopropyltriethoxysilane used was 1 g: 10 mL.
[0015] Furthermore, the concentration of the acetic acid solution used in step (2) is 1 mol / L, which is used to adjust the pH of the system to 5-6.
[0016] Furthermore, the volume concentration of the ammonia solution used in step (2) is 7%, which is used to adjust the pH of the system to 8-9.
[0017] Furthermore, the modified Ti3C2T described in step (3) x The amount of nanosheets used is 0.25~1.0% of the mass of epoxy resin E-44 used.
[0018] Furthermore, the mass ratio of epoxy resin E-44 to polyamide 650 curing agent used in step (3) is 1:1.
[0019] Furthermore, the steel plate used in step (3) has a size of 140×50×1mm, and the vertical pressure applied to it is 1000Pa, which remains unchanged during the curing process.
[0020] This invention first uses acid etching and ice bath ultrasonication to peel off Ti3AlC2 into Ti3C2T. x Nanosheets were grafted onto Ti3C2T nanosheets and then modified with γ-aminopropyltriethoxysilane, thereby significantly improving the modified Ti3C2T. x The nanosheets exhibit chemical stability and are endowed with abundant amino groups on their surface; subsequently, modified Ti3C2T x Nanosheets are incorporated into epoxy resin, and an innovative extrusion-shear stress method is used during coating to simultaneously induce the modification of Ti3C2T by continuously applying vertical pressure during the curing process. x The nanosheets are aligned parallel to the metal substrate and participate in the cross-linking reaction of the epoxy resin.
[0021] The significant advantages of this invention are: 1. This invention uses simple acid etching and ice bath ultrasonication to exfoliate Ti3AlC2 into Ti3C2T. x Nanosheets, resulting in Ti3C2T x Nanosheets are two-dimensional nanolayered materials that can provide excellent barrier properties for composite coatings.
[0022] 2. This invention utilizes γ-aminopropyltriethoxysilane to react with Ti3C2T x Nanosheets are covalently grafted and modified, consuming Ti3C2T through a chemical reaction. x The inherent unstable groups of nanosheets greatly improve the modified Ti3C2Tx The chemical stability of the nanosheets prevents them from oxidizing and degrading in humid air.
[0023] 3. The modified Ti3C2T prepared by grafting γ-aminopropyltriethoxysilane according to the present invention x The nanosheets contain abundant amino groups on their surface, which can significantly enhance the modified Ti3C2T x The compatibility of nanosheets with epoxy resin improves the modification of Ti3C2T. x The dispersibility of nanosheets in epoxy resin, and the modified Ti3C2T rich in amino groups. x Nanosheets can also participate in the cross-linking reaction of epoxy resin, thereby enhancing the structural stability and density of the coating.
[0024] 4. This invention innovatively employs the extrusion-shear stress method to induce modification of Ti3C2T. x The nanosheets are aligned parallel to the metal substrate in the coating. This is achieved by coating a composite coating wet film onto the metal surface, covering it with a silicone pressure plate, and applying a certain vertical pressure. Under this vertical pressure (compressive stress), the wet film thickness is compressed. Subsequently, this compressive stress acting on the wet film transforms into shear stress parallel to the metal substrate, causing the compressed wet film to rapidly diffuse parallel to the metal substrate and outwards. During this process, the modified Ti3C2T... x The nanosheets will also migrate along with the wet film. To reduce the migration and diffusion resistance, modified Ti3C2T... x The nanosheets will migrate within the coating by forming an orientation parallel to the metal substrate. This extrusion-shear stress method is simple and efficient to operate, requires minimal equipment, is low in cost, and is suitable for large-scale applications.
[0025] 5. The extrusion-shear stress method employed in this invention is continuously implemented during the coating curing process, enabling simultaneous stress-induced alignment and epoxy resin crosslinking curing. This significantly reduces the interfacial voids between the nanosheets and the coating resin, ultimately achieving modified Ti3C2T. x The nanosheets are stably oriented parallel to the metal substrate in the coating, which solves the problem that simple physical arrangement structures are prone to relaxation during later curing or use.
[0026] 6. The modified Ti3C2T prepared by this invention x The epoxy composite coating with oriented nanosheets, due to the modification of Ti3C2T x The nanosheets are aligned parallel to the metal substrate in the coating, which maximizes the modification of Ti3C2T. x The nanosheets have high barrier efficiency, and on the other hand, they can block the modified Ti3C2T. x The conductive pathway between the nanosheets and the metal substrate effectively suppresses galvanic corrosion, thereby resulting in the modified Ti3C2T.x The nanosheet-oriented epoxy composite coating has excellent long-lasting anti-corrosion performance.
[0027] 7. The method of this invention is simple to operate, requires little equipment, and is inexpensive, successfully solving the problem of Ti3C2T. x The application of nanosheets in epoxy anti-corrosion coatings faces multiple technical obstacles, such as easy oxidation, easy initiation of galvanic corrosion, difficulty in orientation and unstable arrangement structure, and poor bonding with coating resin. Therefore, it is very suitable for the large-scale preparation of high-performance anti-corrosion coatings. Attached Figure Description
[0028] Figure 1 Ti3C2T prepared in Example 2 x Nanosheets and Ti3C2T x FT-IR image of @APTES nanosheets.
[0029] Figure 2 Ti3C2T prepared in Example 2 x Nanosheets and Ti3C2T x SEM image of @APTES nanosheets.
[0030] Figure 3 Ti3C2T prepared in Example 2 x Cross-sectional SEM image of an epoxy composite coating with oriented @APTES nanosheets.
[0031] Figure 4 Ti3C2T prepared in Example 2 x Nanosheets and Ti3C2T x The dispersion state diagram of @APTES nanosheets after soaking in water for a certain period of time.
[0032] Figure 5 EIS spectra of the composite coatings prepared in Examples 1-3 and Comparative Examples 1-5 after immersion in 3.5wt% NaCl solution for 1 day.
[0033] Figure 6 EIS spectra of the composite coatings prepared in Examples 1-3 and Comparative Examples 1-5 after immersion in 3.5wt% NaCl solution for 10 days. Detailed Implementation
[0034] A modified Ti3C2T x The preparation of an epoxy composite coating with oriented nanosheets includes the following steps: (1)Ti3C2T x Preparation of nanosheets: LiF was dissolved in 12 mol / L HCl solution at a solid-liquid ratio of 1 g:20 mL. Then, Ti3AlC2 powder was added at a mass ratio of 1:1 to LiF. The mixture was stirred in a water bath at 35°C for 24 h, then cooled to room temperature. The mixture was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The supernatant was then placed in ice water under nitrogen protection and sonicated at 350 W for 1 h. After centrifugation at 3500 rpm, the supernatant was collected and freeze-dried to obtain Ti3C2T. x Nanosheets; (2) Modified Ti3C2T x Preparation of nanosheets: γ-aminopropyltriethoxysilane was added to an ethanol / water (19:1, v / v) mixture at a volume ratio of 1:20, and the system was adjusted to a weakly acidic state (pH 5-6) by adding 1 mol / L acetic acid solution. The mixture was then magnetically stirred at room temperature for 6 hours. Following this, the Ti3C2T... x The solid-liquid ratio of nanosheets to γ-aminopropyltriethoxysilane was 1 g: 10 mL. The prepared Ti3C2T nanosheets were then added to the above solution. x Nanosheets were ultrasonically treated for 30 min, and then a 7% (v / v) ammonia solution was added dropwise to adjust the system to a weakly alkaline state (pH 8-9). After stirring at 70 °C for 6 h, the mixture was centrifuged, washed, and freeze-dried to obtain modified Ti3C2T with an amino-rich surface. x Nanosheets; (3) Modified Ti3C2T x Preparation of oriented epoxy composite coatings with nanosheets: The prepared modified Ti3C2T x Nanosheets were ultrasonically dispersed in tetrahydrofuran, and epoxy resin E-44 and polyamide 650 curing agent were added. The mixture was continuously stirred until excess solvent was completely evaporated. Then, the prepared mixture was coated onto a 140×50×1mm steel plate using a 200 μm thick coating rod. Immediately afterward, a silicone mat was placed on top and a vertical pressure of 1000 Pa was applied. The mixture was cured at 40℃ for 48 h (maintaining constant vertical pressure throughout the curing process). Afterward, the silicone mat was peeled off to obtain modified Ti3C2T. x An epoxy composite coating with oriented nanosheets.
[0035] Among them, the modified Ti3C2T mentioned in step (3) x The amount of nanosheets used is 0.25~1.0% of the mass of epoxy resin E-44 used. The mass ratio of epoxy resin E-44 to polyamide 650 curing agent is 1:1.
[0036] The silane-modified Ti3C2T used in this invention xNanosheets and the extrusion-shear stress method have a good synergistic effect in improving the corrosion resistance of composite coatings, and their effect is far greater than the simple sum of their effects. Specifically, this is manifested in: (a) silane modification improves the corrosion resistance of Ti3C2T x (a) The stability of the nanosheets provides a stable and well-dispersed raw material basis for stress-induced alignment; (b) Stress-induced alignment forms a dense barrier layer, which can maximize the effect of modified Ti3C2T. x The barrier advantages of nanosheets; (c) the cross-linking reaction carried out simultaneously under continuous pressure "anchors" the oriented structure in the epoxy network, making its structure stable and durable; (d) the synergistic effect effectively inhibits galvanic corrosion.
[0037] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.
[0038] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.
[0039] Example 1 0.25 wt% Ti3C2T x @APTES nanosheet oriented epoxy composite coating (1)Ti3C2T x Preparation of nanosheets: 1 g of LiF was added to a polytetrafluoroethylene beaker containing 20 mL of HCl solution (12 mol / L) and stirred for 30 min until completely dissolved. Then, 1 g of Ti3AlC2 powder was added, and the mixture was stirred in a 35°C water bath for 24 h. After naturally cooling to room temperature, the mixture was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The resulting supernatant was then placed in ice water under nitrogen protection and sonicated at 350 W for 1 h. Afterward, it was centrifuged at 3500 rpm, and the supernatant was freeze-dried again to obtain Ti3C2T. x Nanosheets; (2) APTES modified Ti3C2T x Preparation of nanosheets: First, 1 mL of APTES was added to 20 mL of an ethanol / water (19:1, v / v) mixture. The pH of the system was adjusted to weakly acidic (pH=5-6) with 1 mol / L acetic acid solution, and the mixture was continuously magnetically stirred at room temperature for 6 h. Then, 0.1 g of Ti3C2T was added while stirring. xNanosheets were prepared and ultrasonically dispersed for 30 min (300 W, 40 kHz). Then, 7 vol% ammonia solution was added dropwise to adjust the pH to weakly alkaline (pH = 8-9). The reaction was stirred in a 70℃ water bath for 6 h. After the reaction was complete, the product was separated by centrifugation and repeatedly washed with an ethanol / water (4:1, v / v) mixture. Finally, APTES-modified Ti3C2T was obtained by freeze-drying. x Nanosheets, denoted as Ti3C2T x @APTES nanosheets; (3) APTES modified Ti3C2T x Preparation of oriented epoxy composite coatings with nanosheets 50mg Ti3C2T x @APTES nanosheets were added to 10 mL of tetrahydrofuran and sonicated for 30 min. Then, 10 g of epoxy resin E-44 and 10 g of polyamide 650 curing agent were added, and the mixture was continuously stirred in an open container until the excess solvent was completely evaporated. The mixture was then coated onto a 140×50×1 mm steel plate using a 200 μm thick coating rod, and immediately covered with a silicone pressure plate. A vertical compressive stress of 1000 Pa was applied, followed by curing at 40 °C for 48 h (the vertical compressive stress was kept constant throughout the curing process). After curing, the silicone pressure plate was peeled off to obtain a modified Ti3C2T containing 0.25 wt%. x Epoxy composite coating on nanosheets.
[0040] Example 2 0.5 wt% Ti3C2T x @APTES nanosheet oriented epoxy composite coating (1)Ti3C2T x Preparation of nanosheets: 1 g of LiF was added to a polytetrafluoroethylene beaker containing 20 mL of HCl solution (12 mol / L) and stirred for 30 min until completely dissolved. Then, 1 g of Ti3AlC2 powder was added, and the mixture was stirred in a 35°C water bath for 24 h. After naturally cooling to room temperature, the mixture was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The resulting supernatant was then placed in ice water under nitrogen protection and sonicated at 350 W for 1 h. Afterward, it was centrifuged at 3500 rpm, and the supernatant was freeze-dried again to obtain Ti3C2T. x Nanosheets; (2) APTES modified Ti3C2T x Preparation of nanosheets: First, 1 mL of APTES was added to 20 mL of an ethanol / water (19:1, v / v) mixture. The pH of the system was adjusted to weakly acidic (pH=5-6) with 1 mol / L acetic acid solution, and the mixture was continuously magnetically stirred at room temperature for 6 h. Then, 0.1 g of Ti3C2T was added while stirring. x Nanosheets were prepared and ultrasonically dispersed for 30 min (300 W, 40 kHz). Then, 7 vol% ammonia solution was added dropwise to adjust the pH to weakly alkaline (pH = 8-9). The reaction was stirred in a 70℃ water bath for 6 h. After the reaction was complete, the product was separated by centrifugation and repeatedly washed with an ethanol / water (4:1, v / v) mixture. Finally, APTES-modified Ti3C2T was obtained by freeze-drying. x Nanosheets, denoted as Ti3C2T x @APTES nanosheets; (3) APTES modified Ti3C2T x Preparation of oriented epoxy composite coatings with nanosheets 100mg Ti3C2T x @APTES nanosheets were added to 10 mL of tetrahydrofuran and sonicated for 30 min. Then, 10 g of epoxy resin E-44 and 10 g of polyamide 650 curing agent were added, and the mixture was continuously stirred in an open container until the excess solvent was completely evaporated. The mixture was then coated onto a 140×50×1 mm steel plate using a 200 μm thick coating rod, and immediately covered with a silicone pressure plate. A vertical compressive stress of 1000 Pa was applied, followed by curing at 40 °C for 48 h (the vertical compressive stress was kept constant throughout the curing process). After curing, the silicone pressure plate was peeled off to obtain a mixture containing 0.5 wt% modified Ti3C2T. x Epoxy composite coating on nanosheets.
[0041] Example 3 1.0 wt% Ti3C2T x @APTES nanosheet oriented epoxy composite coating (1)Ti3C2T x Preparation of nanosheets: 1 g of LiF was added to a polytetrafluoroethylene beaker containing 20 mL of HCl solution (12 mol / L) and stirred for 30 min until completely dissolved. Then, 1 g of Ti3AlC2 powder was added, and the mixture was stirred in a 35°C water bath for 24 h. After naturally cooling to room temperature, the mixture was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The resulting supernatant was then placed in ice water under nitrogen protection and sonicated at 350 W for 1 h. Afterward, it was centrifuged at 3500 rpm, and the supernatant was freeze-dried again to obtain Ti3C2T. x Nanosheets; (2) APTES modified Ti3C2Tx Preparation of nanosheets: First, 1 mL of APTES was added to 20 mL of an ethanol / water (19:1, v / v) mixture. The pH of the system was adjusted to weakly acidic (pH=5-6) with 1 mol / L acetic acid solution, and the mixture was continuously magnetically stirred at room temperature for 6 h. Then, 0.1 g of Ti3C2T was added while stirring. x Nanosheets were prepared and ultrasonically dispersed for 30 min (300 W, 40 kHz). Then, 7 vol% ammonia solution was added dropwise to adjust the pH to weakly alkaline (pH = 8-9). The reaction was stirred in a 70℃ water bath for 6 h. After the reaction was complete, the product was separated by centrifugation and repeatedly washed with an ethanol / water (4:1, v / v) mixture. Finally, APTES-modified Ti3C2T was obtained by freeze-drying. x Nanosheets, denoted as Ti3C2T x @APTES nanosheets; (3) APTES modified Ti3C2T x Preparation of oriented epoxy composite coatings with nanosheets 200mg Ti3C2T x @APTES nanosheets were added to 10 mL of tetrahydrofuran and sonicated for 30 min. Then, 10 g of epoxy resin E-44 and 10 g of polyamide 650 curing agent were added, and the mixture was continuously stirred in an open container until the excess solvent was completely evaporated. The mixture was then coated onto a 140×50×1 mm steel plate using a 200 μm thick coating rod, and immediately covered with a silicone pressure plate. A vertical compressive stress of 1000 Pa was applied, followed by curing at 40 °C for 48 h (the vertical compressive stress was kept constant throughout the curing process). After curing, the silicone pressure plate was peeled off to obtain a mixture containing 1.0 wt% modified Ti3C2T. x Epoxy composite coating on nanosheets.
[0042] Comparative Example 1: Pure Epoxy Coating 10g of epoxy resin E-44 and 10g of polyamide 650 curing agent were added to 10mL of tetrahydrofuran. The mixture was then stirred continuously with the open end until the excess solvent was completely evaporated. The mixture was then uniformly coated onto a steel plate with dimensions of 140×50×1mm using a coating rod with a thickness of 200μm. Finally, the sample was dried in a 40℃ oven for 48 h to obtain a pure epoxy coating.
[0043] Comparative Example 2 0.5 wt% Ti3C2T x Nanosheet epoxy composite coating (1)Ti3C2T x Preparation of nanosheets: 1 g of LiF was added to a polytetrafluoroethylene beaker containing 20 mL of HCl solution (12 mol / L) and stirred for 30 min until completely dissolved. Then, 1 g of Ti3AlC2 powder was added, and the mixture was stirred in a 35°C water bath for 24 h. After naturally cooling to room temperature, the mixture was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The resulting supernatant was then placed in ice water under nitrogen protection and sonicated at 350 W for 1 h. Afterward, it was centrifuged at 3500 rpm, and the supernatant was freeze-dried again to obtain Ti3C2T. x Nanosheets; (2) Ti3C2T x Preparation of nanosheet epoxy composite coating 100mg Ti3C2T x Nanosheets were added to 10 mL of tetrahydrofuran and sonicated for 30 min. Then, 10 g of epoxy resin E-44 and 10 g of polyamide 650 curing agent were added, and the mixture was continuously stirred in an open container until all excess solvent evaporated. The prepared mixture was then coated onto a steel plate with dimensions of 140 × 50 × 1 mm using a coating rod with a thickness of 200 μm. Finally, the sample was dried in a 40 °C oven for 48 h to obtain a sample containing 0.5 wt% Ti3C2T. x Epoxy coating on nanosheets.
[0044] Comparative Example 3 0.5 wt% Ti3C2T x @APTES Nanosheet Epoxy Composite Coating (1)Ti3C2T x Preparation of nanosheets: 1 g of LiF was added to a polytetrafluoroethylene beaker containing 20 mL of HCl solution (12 mol / L) and stirred for 30 min until completely dissolved. Then, 1 g of Ti3AlC2 powder was added, and the mixture was stirred in a 35°C water bath for 24 h. After naturally cooling to room temperature, the mixture was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The resulting supernatant was then placed in ice water under nitrogen protection and sonicated at 350 W for 1 h. Afterward, it was centrifuged at 3500 rpm, and the supernatant was freeze-dried again to obtain Ti3C2T. x Nanosheets; (2) APTES modified Ti3C2T x Preparation of nanosheets: First, 1 mL of APTES was added to 20 mL of an ethanol / water (19:1, v / v) mixture. The pH of the system was adjusted to weakly acidic (pH=5~6) with 1 mol / L acetic acid solution, and the mixture was continuously magnetically stirred at room temperature for 6 h. Then, 0.1 g of Ti3C2T was added while stirring. xNanosheets were prepared and ultrasonically dispersed for 30 min (300 W, 40 kHz). Then, 7 vol% ammonia solution was added dropwise to adjust the pH to weakly alkaline (pH = 8-9). The reaction was stirred in a 70℃ water bath for 6 h. After the reaction was complete, the product was separated by centrifugation and repeatedly washed with an ethanol / water (4:1, v / v) mixture. Finally, APTES-modified Ti3C2T was obtained by freeze-drying. x Nanosheets; (3) APTES modified Ti3C2T x Preparation of nanosheet epoxy composite coating 100mg APTES modified Ti3C2T x Nanosheets were added to 10 mL of tetrahydrofuran and sonicated for 30 min. Then, 10 g of epoxy resin E-44 and 10 g of polyamide 650 curing agent were added, and the mixture was continuously stirred in an open container until the excess solvent was completely evaporated. The prepared mixture was then coated onto a steel plate with dimensions of 140 × 50 × 1 mm using a coating rod with a thickness of 200 μm. Finally, the sample was dried in a 40 °C oven for 48 h to obtain a sample containing 0.5 wt% Ti3C2T. x Epoxy coating on nanosheets.
[0045] Comparative Example 4 In step (3), a vertical compressive stress of 500 Pa is applied, and other operations are the same as in Example 2.
[0046] Comparative Example 5 In step (3), a vertical compressive stress of 1500 Pa is applied, and other operations are the same as in Example 2.
[0047] Figure 1 Ti3C2T prepared in Example 2 x Nanosheets and Ti3C2T x FT-IR image of @APTES nanosheets. The image shows Ti3C2T x Nanosheets at 3440 cm -1 A characteristic OH peak appears at 1060 cm⁻¹. -1 The peak at 537 cm⁻¹ is a characteristic peak of the CF spectrum. -1 The corresponding Ti-O bond absorption; Ti3C2T x @APTES nanosheets retain Ti3C2T x In addition to the characteristic peaks of nanosheets, there are peaks at 1560 cm⁻¹. -1 The NH bending vibration peak appeared at 1070 cm⁻¹, and at 1070 cm⁻¹... -1 The appearance of Si-OC / Si-O-Si stretching vibration peaks at the point indicates the successful modification of the organic molecule APTES.
[0048] Figure 2 Ti3C2T prepared in Example 2 x Nanosheets and Ti3C2T x SEM image of @APTES nanosheets. As can be seen from the image, Ti3C2T... x The nanosheets have a relatively clear layered structure and a wrinkled surface; while Ti3C2T x The surface of the APTES nanosheets is covered with a dense layer of granular material, resulting in overall surface roughening. This roughening phenomenon demonstrates the role of APTES in Ti3C2T. x Covalent grafting on the surface of nanosheets forms an encapsulation layer or nanostructure.
[0049] Figure 3 Ti3C2T prepared in Example 2 x SEM image of the cross-section of the @APTES nanosheet-oriented epoxy composite coating. As can be seen from the image, the Ti3C2T nanosheets are marked with yellow dashed lines. x The APTES nanosheets are distributed in parallel within the coating, exhibiting a tight interfacial bond with the surrounding epoxy resin matrix and exhibiting no obvious pores. This demonstrates that the extrusion-shear stress method successfully induced the directional alignment of the nanosheets, and that cross-linking and curing under continuous pressure resulted in a dense bond with the matrix.
[0050] Figure 4 Ti3C2T prepared in Example 2 x Nanosheets and Ti3C2T x The dispersion state of @APTES nanosheets after immersion in water for different times is shown in the figure. As can be observed from the figure, the Ti3C2T prepared after APTES modification... x @APTES nanosheets exhibit better dispersion stability in water.
[0051] Performance testing The corrosion resistance of the coating was studied using an electrochemical workstation and electrochemical impedance spectroscopy (EIS). The EIS test frequency range was 10 Hz. -2 ~10 5 The frequency is Hz, and the amplitude of the sinusoidal signal is 20mV. The electrolytic cell adopts a three-electrode system, and the steel plate (with a 1cm diameter) is coated with an epoxy coating. 2 A circular test area was used as the working electrode, and a saturated calomel electrode and a platinum wire were used as the reference electrode and counter electrode, respectively. The sample electrodes were immersed in a 3.5 wt% NaCl solution before EIS electrochemical performance testing.
[0052] Figure 5 , 6The figures show the EIS spectra of the composite coatings prepared in Examples 1-3 and Comparative Examples 1-5 after immersion in 3.5 wt% NaCl solution for 1 day and 10 days, respectively. As can be seen from the figures, after immersion in 3.5 wt% NaCl solution for 1 day, the low-frequency impedance value Log(|Z|) of the composite coatings prepared in the examples is significantly lower. 0.01Hz The higher level is mainly attributed to three synergistic factors: firstly, Ti3C2T x Nanosheets themselves possess excellent physical barrier effects; secondly, APTES is used to treat Ti3C2T... x Through covalent grafting modification of nanosheets, the amino functional group (-NH2) of APTES can be grafted onto Ti3C2T. x Surface hydroxyl (-OH) bonds are formed, and hydrogen / covalent bonds are also formed with epoxy resin (EP), eliminating interfacial defects and blocking the penetration channels of corrosive media; finally, Ti3C2T is induced by extrusion-shear stress method. x @APTES nanosheets are aligned parallel to the metal substrate in the coating, maximizing the modification of Ti3C2T. x The nanosheets improve the blocking efficiency, and on the other hand, block Ti3C2T. x The conductive pathway between the @APTES nanosheets and the metal substrate effectively suppresses galvanic corrosion.
[0053] Meanwhile, by comparison, it can be found that the low-frequency impedance value Log(|Z|) of the composite coating obtained in Example 2 is higher. 0.01Hz The reason why the value of Example 1 is higher than that of Example 1 and Example 3 is that Example 1 has Ti3C2T x The addition of @APTES nanosheets was insufficient (0.25wt%), failing to form a continuous and dense barrier network, resulting in poor barrier efficiency; while in Example 3, the Ti3C2T x Excessive addition of @APTES nanosheets (1.0wt%) caused partial aggregation, disrupting the uniformity of the oriented structure.
[0054] Furthermore, the low-frequency impedance value Log(|Z|) of Comparative Example 1 (pure epoxy coating) 0.01Hz The lowest value indicates that it has the weakest ion permeation resistance. In contrast, all Ti3C2T-containing compounds have the lowest ion permeation resistance. x The modified coatings all exhibited higher low-frequency impedance values, fully demonstrating the superior performance of Ti3C2T. x The barrier effect of the lamellar structure—its two-dimensional lamellar structure forms a physical barrier in the coating, enhancing its impermeability. Notably, Comparative Example 3 exhibits better impedance performance than Comparative Example 2, because the modification of APTES improves the impermeability of Ti3C2T. x The chemical stability of APTES is improved, and the compatibility and dispersibility of the filler-matrix interface are optimized. This is due to the siloxane (Si-O-) and Ti3C2T of APTES. xSurface hydroxyl (-OH) bonds eliminate Ti3C2T x The unstable groups greatly improve the performance of Ti3C2T x Chemical stability; modified Ti3C2T x The surface of the @APTES nanosheets contains a large number of amino groups (-NH2), which enhances compatibility with epoxy resin and improves dispersibility. It can also participate in the cross-linking reaction of epoxy resin, eliminate interfacial defects, and block the penetration channels of corrosive media. Further observation revealed that the low-frequency impedance value of Example 2 was better than that of Comparative Example 3, mainly due to the oriented Ti3C2T... x @APTES nanosheets form a dense barrier layer parallel to the metal substrate, forcing corrosive media to take longer, tortuous paths, thereby maximizing the two-dimensional Ti3C2T x Barrier efficiency of @APTES nanosheets.
[0055] Furthermore, as the soaking time was extended to 10 days, it was found that the performance of Comparative Example 2 decreased significantly, with its low-frequency impedance value dropping to the lowest level. This can be attributed to: (1) Ti3C2T x The poor chemical stability of Ti3C2T caused partial cracking of its structure, resulting in a decrease in barrier performance; (2) High conductivity Ti3C2T x It forms a corrosion galvanocoupler with the steel substrate, resulting in an accelerated corrosion effect. In contrast, Ti3C2T... x The composite coatings of @APTES (Examples 1-3 and Comparative Example 3) exhibit superior long-term stability, and Ti3C2T x The composite coatings with @APTES oriented alignment (Examples 1-3) exhibit better protective performance (low-frequency impedance value higher than 1×10⁻⁶). 9 Ω·cm 2 Ultimately, among all the coatings examined, 0.50 wt% Ti3C2T x The @APTES nanosheet oriented epoxy composite coating has the highest impedance value and the best protective performance. This result fully demonstrates that the combination of silane modification technology and extrusion-shear stress-induced alignment technology produced a significant synergistic effect, effectively solving the limitations of single technology and obtaining long-lasting anti-corrosion performance far exceeding expectations.
[0056] Furthermore, compared to Comparative Examples 4 and 5, the coating prepared by applying a pressure of 1000 Pa in Example 2 exhibited the best barrier performance in both the initial and later stages of immersion. This is mainly because pressure is related to the orientation and dispersion state of the two-dimensional materials in the coating. A moderate pressure (1000 Pa) is most conducive to the highly parallel, dense, and defect-free directional arrangement of the two-dimensional material sheets on the substrate surface, thereby forming the most effective labyrinthine barrier path, giving the coating the best initial protective performance, and still providing the best resistance to media penetration after 10 days of immersion. However, too low a pressure (500 Pa) is insufficient to fully orient all the two-dimensional materials, resulting in disordered sheet arrangement or gaps, making it easier for corrosive media to penetrate through defect paths, thus weakening the barrier effect. While too high a pressure (1500 Pa) may also promote the parallel arrangement of the two-dimensional materials, it may cause some two-dimensional material sheets to be excessively compressed, overlapped, or even damaged, destroying their ideal dispersion state.
[0057] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. A modified Ti3C2T x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: First, Ti3AlC2 is peeled off into Ti3C2T through acid etching and ultrasonic treatment. x Nanosheets; then, γ-aminopropyltriethoxysilane was used to treat Ti3C2T x Nanosheets were covalently grafted to prepare amino-rich modified Ti3C2T. x Nanosheets; then modified Ti3C2T x Nanosheets are incorporated into epoxy resin, and during the coating curing process, continuous vertical pressure is applied to convert extrusion stress into shear stress parallel to the substrate, thereby simultaneously inducing the modification of Ti3C2T. x The oriented arrangement of nanosheets and the cross-linking reaction of epoxy resin involving amino groups on their surface lead to the preparation of modified Ti3C2T. x An epoxy composite coating with oriented nanosheets.
2. The modified Ti3C2T according to claim 1 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: Specifically, the following steps are included: (1)Ti3C2T x Preparation of nanosheets: LiF was dissolved in 12 mol / L HCl solution, and Ti3AlC2 powder was added. The mixture was stirred in a water bath and then cooled to room temperature. The solution was washed with deionized water by centrifugation until the pH of the supernatant reached 6. The supernatant was then sonicated in ice water under nitrogen protection. After centrifugation, the supernatant was collected and freeze-dried to obtain Ti3C2T. x Nanosheets; (2) Modified Ti3C2T x Preparation of nanosheets: γ-aminopropyltriethoxysilane was added to an ethanol / water mixture, and acetic acid solution was added to adjust the system to a weakly acidic state. The mixture was then magnetically stirred at room temperature for 6 hours, followed by the addition of the prepared Ti3C2T. x Nanosheets were ultrasonically treated for 30 min, and then ammonia solution was added dropwise to adjust the system to weakly alkaline. After stirring at 70 °C for 6 h, the mixture was centrifuged, washed, and freeze-dried to obtain modified Ti3C2T with an amino-rich surface. x Nanosheets; (3) Modified Ti3C2T x Preparation of oriented epoxy composite coatings with nanosheets: The prepared modified Ti3C2T x Nanosheets were ultrasonically dispersed in tetrahydrofuran, and epoxy resin E-44 and polyamide 650 curing agent were added. The mixture was stirred continuously until excess solvent was completely evaporated. Then, the prepared mixture was coated onto a steel plate using a coating rod with a thickness of 200 μm. A silicone pressure plate was immediately placed on top and vertical pressure was applied. After curing at 40°C for 48 hours, the silicone pressure plate was peeled off to obtain modified Ti3C2T. x An epoxy composite coating with oriented nanosheets.
3. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The solid-liquid ratio of LiF and HCl solution used in step (1) is 1g:20mL, and the mass ratio of LiF and Ti3AlC2 powder used is 1:1; the water bath stirring temperature is 35℃ and the time is 24h; the ultrasonic treatment power is 350W and the time is 1h.
4. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The volume ratio of γ-aminopropyltriethoxysilane to the ethanol / water mixture used in step (2) is 1:20, and the volume ratio of ethanol to water in the ethanol / water mixture is 19:
1.
5. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The Ti3C2T added in step (2) x The solid-liquid ratio of the nanosheets to the γ-aminopropyltriethoxysilane used was 1 g: 10 mL.
6. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The acetic acid solution used in step (2) has a concentration of 1 mol / L and is used to adjust the pH of the system to 5-6; the ammonia solution used has a volume concentration of 7% and is used to adjust the pH of the system to 8-9.
7. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The modified Ti3C2T described in step (3) x The amount of nanosheets used is 0.25~1.0% of the mass of epoxy resin E-44 used.
8. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The mass ratio of epoxy resin E-44 to polyamide 650 curing agent used in step (3) is 1:
1.
9. A modified Ti3C2T according to claim 2 x A method for preparing a nanosheet-oriented epoxy composite coating, characterized in that: The steel plate used in step (3) has a size of 140×50×1mm, and the vertical pressure applied on it is 1000Pa, which remains unchanged during the curing process.
10. A modified Ti3C2T prepared by any one of claims 1 to 9 x An epoxy composite coating with oriented nanosheets.