A method for preparing fine-grained Al-Ti-SiC composite coatings by electrodeposition

Abstract

This invention aims to prepare a particle-reinforced aluminum-based composite coating, Al-Ti-SiC, by electrodeposition. Anhydrous TiCl4 is selected as the Ti source to provide a large number of Ti ions, which refine the aluminum. Then, uniformly dispersed high-strength nano-sized SiC particles further refine the aluminum, resulting in a fine-grained and dense Al-Ti-SiC composite coating. This invention uses an AlCl3-LiAlH4-Benzene-THF organic solvent system, which has good dispersibility and can effectively disperse ceramic reinforcing particles. The uniformly dispersed SiC particles in the solution can absorb a small amount of heat generated during the reaction, maintaining system stability. Furthermore, the SiC particles possess high hardness and can refine the grains through physical pinning. Anhydrous TiCl4 is prone to hydrolysis in air, producing a large amount of hydrochloric acid droplets and releasing heat. To avoid solution failure, this invention precisely controls the addition method, timing, and amount of anhydrous TiCl4 and SiC particles to achieve effective and stable solution. The coating prepared by this invention has fine grains and strong corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical deposition, specifically relating to a method for preparing an Al-Ti-SiC composite coating. Background Technology

[0002] While aluminum and aluminum alloys possess fundamental properties such as lightweight and ease of processing, they often exhibit significant shortcomings under extreme working conditions, including insufficient strength and stiffness, poor wear resistance, high coefficient of thermal expansion, and easy performance degradation at high temperatures. In contrast, particle-reinforced aluminum matrix composites achieve a comprehensive leap in material properties by introducing high-hardness ceramic particles (such as silicon carbide and alumina) into the aluminum matrix. The reinforcing particles not only significantly improve the material's specific strength, specific stiffness, and wear resistance but also significantly reduce the coefficient of thermal expansion, endowing the material with excellent high-temperature stability and dimensional controllability. Electrodeposition, as an important material preparation technology, offers advantages over other traditional methods, including low process cost, ease of scaling, fast deposition rate, high deposition efficiency, and precise control over morphology and microstructure, resulting in high process flexibility and wide applicability to various materials.

[0003] Currently, the electrodeposition preparation of particle-reinforced aluminum-based composite coatings mainly employs ionic systems. Coatings prepared using these systems are prone to hydrogen evolution reactions and hydrogen embrittlement, leading to a decrease in overall coating performance. This invention utilizes a room-temperature organic solvent system, AlCl3-LiAlH4-Benzene-THF-TiCl4-SiC. This system requires a strictly anhydrous and oxygen-free environment to avoid hydrogen evolution reactions during preparation. Furthermore, the organic solvent has low surface tension and good wettability, effectively reducing and controlling the agglomeration of second-phase particles. In addition, anhydrous TiCl4 directly provides a large number of Ti ions, significantly promoting aluminum refinement. The introduction of SiC particles hinders grain growth and increases nucleation sites. The synergistic effect of Ti refining Al and the physical pinning effect of second-phase particles inhibits grain growth, refines the grains, and prepares a high-strength and dense particle-reinforced aluminum-based composite coating. Summary of the Invention

[0004] The purpose of this invention is to prepare a fine-grained Al-Ti-SiC composite coating using the AlCl3-LiAlH4-Benzene-THF-TiCl4-SiC system.

[0005] This invention uses 40nm SiC particles as the second phase particles, anhydrous TiCl4 as the Ti source, and AlCl3-LiAlH4-Benzene-THF as the electrodeposition reaction system. The solution preparation process must be carried out under ice bath conditions to overcome the large amount of heat generated by the strong reducing agent LiAlH4 and the problem of solution deterioration caused by heat from the addition of anhydrous TiCl4. Furthermore, to prevent air from entering and causing side reactions between LiAlH4 and TiCl4 in the solution, the beaker mouth must be sealed when operating outside the glove box, and it must be resealed promptly after each addition operation.

[0006] To ensure that TiCl4 effectively provides a titanium source, it needs to be added slowly according to its solubility at different temperatures. Based on the above requirements, this invention determines the timing of adding anhydrous TiCl4 as follows: approximately 1 hour after the mixing of benzene, tetrahydrofuran, anhydrous AlCl3, and LiAlH4 is completed. During addition, the temperature of the water bath should be kept below 0°C. When adding TiCl4, a thin glass tube should be used as a guide tube to slowly add TiCl4 dropwise.

[0007] SiC, as a ceramic particle with high hardness and strong corrosion resistance, is widely used in actual industrial production due to its low cost. SiC particles are adsorbed onto the cathode surface via electrodeposition. The basic principle of the SiC particle-reinforced aluminum-based coating of this invention is that during grain growth, uniformly dispersed nanoscale SiC particles hinder grain growth through physical pinning, thus refining the grains and continuously forming new nucleation sites near the grains. In summary, SiC particles stably adsorbed at the grain boundaries can both refine the coating grains and improve strength through pinning, and further enhance the strength and corrosion resistance of the coating due to SiC's inherent high hardness and other properties. To achieve effective refinement of the coating through pinning by SiC particles, the SiC particles used as the reinforcing phase in this invention are uniformly dispersed using the dispersibility of organic solvents and ultrasonic vibration, avoiding agglomeration.

[0008] (Detailed implementation steps) A method for preparing fine-grained Al-Ti-SiC composite coatings by electrodeposition is as follows: (1) Preparation of plating solution Place anhydrous AlCl3, LiAlH4, and SiC particles into a glove box. Remove the beaker containing the rotor and the spatula from the drying oven and place them on a tray. Then, place the tray into the glove box, seal it, and fill it with nitrogen. Once the glove box is completely filled with nitrogen, weigh the chemicals. Weigh anhydrous AlCl3 and LiAlH4 using a balance, placing them in a beaker with a molar ratio ranging from 3:1 to 4.1:1. Then, measure SiC particles with a concentration ranging from 6 g / L to 36 g / L and add them to the beaker. Seal the weighed beaker, remove it from the glove box, and place it in a fume hood under ice bath conditions on a magnetic stirrer. Measure 40 mL of benzene using a 60 mL syringe and slowly pour it along the wall of the sealed beaker. Then, measure 10 mL of tetrahydrofuran using a 20 mL syringe and slowly pour it along the wall of the beaker. To prevent the tetrahydrofuran from deteriorating, this process must be carried out under ice bath conditions, and the pouring process must be slow. After adding tetrahydrofuran completely, seal the beaker and adjust the stirring speed to 200 rpm. Stir for 1 hour. After stirring, under ice bath conditions, use a 1 ml syringe to draw a total of 1.12 mL of anhydrous TiCl4 in two separate injections. Using a thin glass tube as a guide tube, place the bottom of the tube below the liquid surface and slowly add anhydrous TiCl4 into the solution by pushing the syringe from the opening of the glass tube. After adding, seal the beaker again and continue stirring for 1 hour. After stirring, disperse the solution by ultrasonication for 30 minutes.

[0009] (2) Aluminum substrate treatment The aluminum sheet was polished smooth with 1000 and 2000 grit sandpaper in turn. Then, it was chemically degreased to remove the oil stains on the surface of the aluminum sheet. After that, it was washed with deionized water and then placed in a vacuum drying oven to dry for later use.

[0010] (3) Copper substrate treatment The copper sheet is polished smooth with 1000 and 2000 grit sandpaper in sequence. Then, chemical degreasing is performed to remove the oil stains on the surface of the copper sheet. Next, pre-etching and weak etching are performed with dilute hydrochloric acid to remove the oxide film. Finally, it is cleaned with deionized water and then placed in a vacuum drying oven to dry for later use.

[0011] (4) Constant current electrodeposition Using an aluminum sheet as the anode and a copper sheet as the cathode, the current density is controlled at 5~30 mA / cm². 2 With a plating bath temperature of 10~30℃ and an electrodeposition time of 30~45min, a dense Al-Ti-SiC composite coating with uniform particle distribution can be obtained.

[0012] (5) Sample processing After electrodeposition is complete, the coating surface is in an active state with some residual electrolyte when the sample is removed. When exposed to air, it is prone to react with water and oxygen in the air. Therefore, after the sample is removed, anhydrous ethanol should be added slowly immediately for cleaning. After cleaning for 1 minute, place the coated part in a beaker containing anhydrous ethanol (do not let the coated part touch the beaker wall or bottom) and ultrasonically clean for 30 seconds. After the cleaning operation is completed, dry it with cold air to avoid phase change caused by high temperature.

[0013] The results that can be achieved by meeting the above preparation requirements are: the prepared Al-Ti-SiC composite coating is dense and has fine grains, and the SiC particles are uniformly dispersed without agglomeration. Attached Figure Description

[0014] Figure 1 Here is a SEM image of the composite coating obtained in this invention; Figure 2 The image shows the EDS energy spectrum of the composite coating obtained in this invention. Figure 3 The XRD pattern of the composite coating obtained in this invention is shown below. Figure 4 This is an elemental surface scan of the composite coating obtained in this invention. Detailed Implementation

[0015] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] This invention specifically relates to a method for preparing fine-grained Al-Ti-SiC by electrodeposition on a copper substrate, which is described in detail below through specific examples. These examples are only a portion of the embodiments of this invention and not all of them. Example 1

[0017] (1) Preparation of plating solution Place anhydrous AlCl3, LiAlH4, and SiC particles into a glove box. Remove the beaker containing the rotor and the spatula from the drying oven and place them on a tray. Then, place the tray into the glove box, seal it, and fill it with nitrogen. Once the glove box is completely filled with nitrogen, weigh the chemicals. Weigh 8.00g of anhydrous AlCl3 and 0.56g of LiAlH4 into the beaker, then weigh 1.4g of SiC particles into the beaker. Seal the beaker containing the weighed chemicals, remove it from the glove box, and place it in a fume hood under ice bath conditions on a magnetic stirrer. Measure 40ml of benzene using a 60mL syringe and slowly pour it along the wall of the sealed beaker. Then, measure 10ml of tetrahydrofuran using a 20mL syringe and slowly pour it along the wall of the beaker. To prevent the tetrahydrofuran from deteriorating, this process must be carried out under ice bath conditions, and the pouring process must be slow. After adding tetrahydrofuran completely, seal the beaker and adjust the stirring speed to 200 rpm. Stir for 1 hour. After stirring, under ice bath conditions, use a 1 ml syringe to draw a total of 1.12 mL of anhydrous TiCl4 in two separate injections. Using a thin glass tube as a guide tube, place the bottom of the tube below the liquid surface and slowly add anhydrous TiCl4 into the solution by pushing the syringe from the opening of the glass tube. After adding, seal the beaker again and continue stirring for 1 hour. After stirring, disperse the solution by ultrasonication for 30 minutes.

[0018] (2) Aluminum substrate treatment The aluminum sheet was polished smooth with 1000 and 2000 grit sandpaper in turn. Then, it was chemically degreased to remove the oil stains on the surface of the aluminum sheet. After that, it was washed with deionized water and then placed in a vacuum drying oven to dry for later use.

[0019] (3) Copper substrate treatment The copper sheet is polished smooth with 1000 and 2000 grit sandpaper in sequence. Then, chemical degreasing is performed to remove the oil stains on the surface of the copper sheet. Next, pre-etching and weak etching are performed with dilute hydrochloric acid to remove the oxide film. Finally, it is cleaned with deionized water and then placed in a vacuum drying oven to dry for later use.

[0020] (4) Constant current electrodeposition Using an aluminum sheet as the anode and a copper sheet as the cathode, the current density is controlled at 30 mA / cm². 2 With a plating bath temperature of 20℃ and an electrodeposition time of 45min, a dense Al-Ti-SiC composite coating with uniform particle distribution can be obtained.

[0021] (5) Sample processing When electrodeposition is complete, the coating surface is in an active state and contains some residual electrolyte when the sample is removed. When exposed to air, it is prone to react with water and oxygen in the air. When removing the sample, anhydrous ethanol should be added slowly and immediately for cleaning. After cleaning for 1 minute, place the coated part in a beaker containing anhydrous ethanol (do not let the coated part touch the beaker wall or bottom) and ultrasonically clean for 30 seconds. After cleaning, dry with cold air to avoid phase transition caused by high temperature.

[0022] The results achievable by meeting the above preparation requirements are: the prepared Al-Ti-SiC composite coating is dense with fine grains, and the SiC particles are uniformly dispersed without agglomeration. The SEM images, EDS spectra, XRD patterns, and elemental surface scans of the samples are shown below. Figure 1 , Figure 2 , Figure 3 , Figure 4 . Example 2

[0023] (1) Preparation of plating solution Place anhydrous AlCl3, LiAlH4, and SiC particles into a glove box. Remove the beaker containing the rotor and the spatula from the drying oven and place them on a tray. Then place the tray into the glove box, seal it, and fill it with nitrogen. Once the glove box is completely filled with nitrogen, weigh the chemicals. Weigh 8.00g of anhydrous AlCl3 and 0.56g of LiAlH4 into the beaker, then measure 1.0g of SiC particles and add them to the beaker. Seal the weighed beaker, remove it from the glove box, and place it in a fume hood under ice bath conditions with a magnetic stirrer. Use a 60mL syringe to measure 40mL of benzene and slowly pour it into the sealed beaker along the wall. Then use a 20mL syringe to measure 10mL of tetrahydrofuran and slowly pour it into the beaker along the wall. To prevent the tetrahydrofuran from deteriorating, this process must be carried out under ice bath conditions and the pouring process must be slow. After adding tetrahydrofuran completely, seal the beaker and adjust the stirring speed to 200 rpm. Stir for 1 hour. After stirring, under ice bath conditions, use a 1 mL syringe to draw a total of 1.12 mL of anhydrous TiCl4 in two separate injections. Using a thin glass tube as a guide tube, place the bottom of the tube below the liquid surface and slowly add anhydrous TiCl4 into the solution by pushing the syringe through the glass tube opening. After adding, seal the beaker again and continue stirring for 1 hour. After stirring, disperse the solution using ultrasound for 30 minutes.

[0024] (2) Aluminum substrate treatment The aluminum sheet was polished smooth with 1000 and 2000 grit sandpaper in turn. Then, it was chemically degreased to remove the oil stains on the surface of the aluminum sheet. After that, it was washed with deionized water and then placed in a vacuum drying oven to dry for later use.

[0025] (3) Copper substrate treatment The copper sheet is polished smooth with 1000 and 2000 grit sandpaper in sequence. Then, chemical degreasing is performed to remove the oil stains on the surface of the copper sheet. Next, pre-etching and weak etching are performed with dilute hydrochloric acid to remove the oxide film. Finally, it is cleaned with deionized water and then placed in a vacuum drying oven to dry for later use.

[0026] (4) Constant current electrodeposition Using an aluminum sheet as the anode and a copper sheet as the cathode, the current density is controlled at 30 mA / cm². 2 With a plating bath temperature of 30℃ and an electrodeposition time of 45min, a dense Al-Ti-SiC composite coating with uniform particle distribution can be obtained.

[0027] (5) Sample processing When electrodeposition is complete, the coating surface is in an active state and contains some residual electrolyte when the sample is removed. When exposed to air, it is prone to react with water and oxygen in the air. When removing the sample, anhydrous ethanol should be added slowly and immediately for cleaning. After cleaning for 1 minute, place the coated part in a beaker containing anhydrous ethanol (do not let the coated part touch the beaker wall or bottom) and ultrasonically clean for 30 seconds. After cleaning, dry with cold air to avoid phase transition caused by high temperature.

[0028] The results that can be achieved by meeting the above preparation requirements are: the prepared Al-Ti-SiC composite coating is dense and has fine grains, and the SiC particles are uniformly dispersed without agglomeration.

Claims

1. Preparation of plating solution: Place anhydrous AlCl3, LiAlH4, and SiC particles into a glove box. Remove a beaker containing a rotor and a spatula from the drying oven and place them on a tray. Then place the tray into the glove box, seal it, and fill it with nitrogen. Once the glove box is completely filled with nitrogen, weigh the chemicals. Weigh anhydrous AlCl3 and LiAlH4 using a balance and place them in a beaker with a molar ratio of 3:1 to 4.1:

1. Then measure SiC particles with a concentration range of 6 g / L to 36 g / L and add them to the beaker. Seal the beaker containing the weighed chemicals, remove it from the glove box, and place it in a fume hood under ice bath conditions with a magnetic stirrer. Measure 40 mL of benzene using a 60 mL syringe and slowly pour it along the wall of the sealed beaker. Measure 10 mL of tetrahydrofuran using a 20 mL syringe and slowly pour it into the beaker along the wall. To prevent the tetrahydrofuran from deteriorating, this process should be carried out in an ice bath and the pouring process should be slow. After the tetrahydrofuran is completely added, seal the beaker and adjust the stirring speed to 200 rpm. Stir for 1 hour. After stirring, under ice bath conditions, use a 1 mL syringe to draw a total of 1.12 mL of anhydrous TiCl4 in two portions. Using a thin glass tube as a guide tube, place the bottom of the tube below the liquid surface and slowly add the anhydrous TiCl4 into the solution by pushing the syringe through the glass tube opening. After the addition is complete, seal the beaker again and continue stirring for 1 hour. After stirring is complete, disperse the solution ultrasonically for 30 minutes.

2. Aluminum substrate treatment: Polish the aluminum sheet smooth with 1000 and 2000 grit sandpaper in sequence, then perform chemical degreasing to remove oil stains from the surface of the aluminum sheet, then clean it with deionized water, and after washing, put it in a vacuum drying oven to dry it for later use.

3. Copper substrate treatment: Polish the copper sheet smooth with 1000 and 2000 grit sandpaper in sequence, then perform chemical degreasing to remove oil stains on the surface of the copper sheet, then perform pre-etching and weak etching with dilute hydrochloric acid to remove the oxide film, and finally clean with deionized water. After rinsing, place it in a vacuum drying oven to dry for later use.

4. Constant current electrodeposition: Using an aluminum sheet as the anode and a copper sheet as the cathode, the current density is controlled at 5~30 mA / cm². 2 With a plating bath temperature of 10~30℃ and an electrodeposition time of 30~45min, a dense Al-Ti-SiC composite coating with uniform particle distribution can be obtained.

5. After electrodeposition is complete, the coating surface is in an active state with some residual electrolyte when the sample is removed. When exposed to air, it is prone to react with water and oxygen in the air. When removing the sample, anhydrous ethanol should be added slowly immediately for cleaning. After cleaning for 1 minute, place the coated part in a beaker containing anhydrous ethanol (do not let the coated part touch the beaker wall or bottom) and ultrasonically clean for 30 seconds. After cleaning, dry with cold air to avoid phase change caused by high temperature.

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