Tourmaline composite coating and electrophoretic deposition method thereof

Abstract

The invention relates to a tourmaline composite coating and an electrophoretic deposition method thereof. The electrophoretic deposition method comprises the following steps: firstly, coating a solution containing rare earth elements on a pretreated metal surface, and drying to obtain metal coated with the rare earth elements; then the metal coated with the rare earth elements is placed in electrophoretic liquid for electrophoretic deposition; the electrophoresis liquid contains tourmaline, a thermoelectric material, a compound containing rare earth elements and a metal oxide; and finally, the metal subjected to electrophoretic deposition is dried, annealed, ground and polished, and the tourmaline composite coating deposited on the surface of the metal is obtained. According to the electrophoretic deposition method, the binding force between the tourmaline composite coating and a metal matrix can be improved, the tourmaline composite coating obtained through deposition is more uniform, and the tourmaline composite coating obtained through deposition has the functional characteristics of tourmaline, good corrosion resistance and wear resistance, and the service life of the tourmaline composite coating is prolonged. The wear resistance of the metal can be improved, and the service life of the metal is prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of material surface treatment, and particularly relates to a tourmaline composite coating and an electrophoretic deposition method thereof. Background Art

[0002] Metals are widely used in industry and daily life, and their surface properties are crucial for their functions and applications.

[0003] Tourmaline is a borosilicate crystal and may contain elements such as aluminum, iron, magnesium, sodium, lithium, potassium, etc. Tourmaline has unique physical and chemical properties, such as functions of releasing negative ions and far-infrared radiation. Coating it on the metal surface can endow the metal with new properties. Existing electrophoretic methods have problems such as insufficient bonding force between the coating and the metal substrate and uneven distribution of tourmaline particles when coating tourmaline, which will affect the quality and performance of the coating.

[0004] For example, the patent application with the application number: 202411650156.4A discloses a metal sheet for releasing negative ions and a processing technology. The metal sheet in the present invention comprises the following components in parts by weight: 20 - 100 parts of negative ion generating material, 1 - 20 parts of binder, 1 - 20 parts of dispersant, and 2 - 30 parts of stabilizer; the negative ion generating material is composed of tourmaline powder and qibingshi powder. This metal sheet can continuously and stably release negative ions, can effectively improve the surrounding air environment, improve air quality, and can reduce dust adsorption and bacterial growth when applied in fields such as interior decoration. The processing technology of this invention is simple and easy to operate, and different base metal plates and negative ion release layer materials can be selected according to actual needs, adapting to various production scales and application scenarios. However, this metal sheet coats the negative ion release layer by spraying, and the bonding between the negative ion release layer and the substrate is poor.

[0005] Therefore, providing a method for uniformly coating tourmaline on the metal surface has become an urgently needed problem to be solved. Summary of the Invention

[0006] Based on the above technical background, the main object of the present invention is to provide a tourmaline composite coating and an electrophoretic deposition method thereof to overcome the deficiencies in the prior art.

[0007] To achieve the foregoing invention object, the technical solutions adopted by the present invention include:

[0008] In the first aspect of the present invention, there is provided an electrophoretic deposition method for a tourmaline composite coating, and the electrophoretic deposition method comprises the following steps:

[0009] Step 1, pretreat the metal, mix a compound containing rare earth elements and ethanol to obtain a solution containing rare earth elements, coat the solution containing rare earth elements on the surface of the pretreated metal, and dry to obtain a metal coated with rare earth elements.

[0010] Step 2: Add tourmaline, dispersant, surfactant and conductive salt into water, then add thermoelectric material, rare earth element-containing compound and metal oxide, and stir evenly to obtain an electrophoretic solution;

[0011] Step 3: Place the metal coated with rare earth elements in the electrophoretic solution for electrophoretic deposition;

[0012] Step 4: Dry the metal after electrophoretic deposition, then perform annealing treatment, and finally perform grinding and polishing to obtain a tourmaline composite coating deposited on the metal surface.

[0013] In Step 1,

[0014] Preferably, the pretreatment includes: cleaning, degreasing and grinding the metal in sequence;

[0015] More preferably, the cleaning includes: wiping the metal surface with acetone;

[0016] More preferably, the degreasing includes: soaking the metal in a 5-15% sodium hydroxide solution for 10-20 min;

[0017] More preferably, the grinding includes: grinding until the surface roughness of the metal reaches 3-5 μm.

[0018] Preferably, the mass fraction of the rare earth element-containing solution is 0.05-0.2%; and / or,

[0019] Preferably, the drying conditions are: drying at 50-70 °C for 5-15 min.

[0020] In Step 2,

[0021] Preferably, the dispersant is selected from one or more of sodium citrate, polyethylene glycol, triethylhexyl phosphate, sodium dodecyl sulfate, methyl pentanol, cellulose derivatives and ammonium polyacrylate; and / or,

[0022] Preferably, the surfactant is selected from one or more of linear alkylbenzene sulfonate, α-olefin sulfonate and stearic acid; and / or,

[0023] Preferably, the conductive salt is selected from one of sodium chloride and potassium chloride; and / or,

[0024] Preferably, the mass ratio of the tourmaline, dispersant, surfactant and conductive salt is 2-6:1-3:0.5-2:0.2-0.5.

[0025] Preferably, the thermoelectric material is selected from one or more of BaTiO3, ZnO and PVDF;

[0026] Preferably, based on the total mass of tourmaline, dispersant, surfactant and conductive salt being 100%, the addition amount of the thermoelectric material is 15-30%.

[0027] Preferably, the rare earth element-containing compound is cerium dioxide, and the particle size of the cerium dioxide is 5-15 nm;

[0028] Preferably, based on the total mass of tourmaline, dispersant, surfactant and conductive salt being 100%, the addition amount of the rare earth element-containing compound is 5-25 wt%.

[0029] Preferably, the metal oxide is selected from one or more of zinc oxide, manganese oxide and titanium dioxide;

[0030] Preferably, based on the total mass of tourmaline, dispersant, surfactant and conductive salt being 100%, the addition amount of the metal oxide is 5-15%.

[0031] In Step 3,

[0032] Preferably, the conditions for electrophoretic deposition are: increasing the voltage to the electrophoretic deposition voltage at a voltage increase rate of 3-7 V / s, the electrophoretic deposition voltage is 30-60 V, the current is 0.1-0.5 A, and the electrophoretic deposition time is 8-20 min.

[0033] In Step 4,

[0034] Preferably, the drying temperature is 70-90 °C, and the drying time is 1-3 h; and / or,

[0035] Preferably, the annealing treatment includes: increasing the temperature to 250-350 °C at a heating rate of 3-6 °C / min, holding at this temperature for 20-45 min, and then increasing the temperature to 500-600 °C at a heating rate of 3-6 °C / min, and holding at this temperature for 1-3 h.

[0036] The second aspect of the present invention lies in providing a tourmaline composite coating deposited by the electrophoretic deposition method according to the first aspect of the present invention.

[0037] The beneficial effects of the present invention:

[0038] (1) The present invention uses a gradient deposition method to deposit on the metal surface. First, a rare earth element-containing compound is spin-coated on the metal surface, and then tourmaline is deposited by electrophoretic deposition. This can not only enhance the adhesion of the tourmaline layer, but also enhance the catalytic performance, the release of negative ion concentration, the antioxidant property, as well as the piezoelectric coefficient and thermoelectric power factor of the tourmaline composite coating, and extend the service life of the material.

[0039] Tourmaline can directly release negative ions, emit far-infrared radiation, and enhance the environmental friendliness and environmental protection and health value of products.

[0040] (2) Before the electrophoretic deposition method of the present invention, the metal needs to be pretreated. The pretreatment has the following functions: ① By pretreatment, the roughness of the metal surface can be increased, so that a mechanical bite is formed between the tourmaline composite coating and the metal substrate, and the bonding force between the tourmaline composite coating and the substrate is improved.

[0041] ② Mechanical bite: After pretreatment, the roughness of the metal surface increases, and the frictional force between the tourmaline composite coating and the substrate increases, so that the tourmaline composite coating and the metal substrate form a more firm bond.

[0042] ③ Chemical bond combination: Chemical bonds can be formed between the tourmaline particles and the atoms on the surface of the metal substrate, further enhancing the bonding force between the tourmaline composite coating and the metal substrate.

[0043] (3) The electrophoretic solution of the present invention is prepared from tourmaline, a dispersant, a surfactant, and a conductive salt. Adding a dispersant and a surfactant to the electrophoretic solution can evenly disperse the tourmaline particles, and they can be more evenly deposited on the surface of the metal substrate during electrophoresis, thereby improving the uniformity and performance of the tourmaline composite coating.

[0044] At the same time, the added dispersant and surfactant can prevent the agglomeration of tourmaline particles and keep the tourmaline particles in a uniformly dispersed state in the solution.

[0045] Under the action of an electric field, the tourmaline particles in the electrophoretic solution of the present invention can be evenly deposited on the metal surface to form a uniform tourmaline composite coating.

[0046] (4) A thermoelectric material, a compound containing rare earth elements, and a metal oxide are also added to the electrophoretic solution of the present invention. The metal oxide can photocatalytically produce active oxygen; the compound containing rare earth elements can not only enhance the piezoelectric performance of the tourmaline composite coating but also regulate the carrier concentration, thereby optimizing the thermoelectric performance; the thermoelectric material can induce a local electric field to promote the surface charge separation of CeO2. Through the synergistic effect of the thermoelectric material, the compound containing rare earth elements, and the metal oxide, the performance of the tourmaline composite coating can be further enhanced.

[0047] (5) The tourmaline composite coating deposited by the electrophoretic deposition method of the present invention not only has the functional characteristics of tourmaline but also has good corrosion resistance and wear resistance, and can improve the anti-wear performance of the metal.

[0048] The tourmaline composite coating can release negative ions, emit far-infrared radiation, and enhance the environmental friendliness and environmental protection and health value of products.

[0049] The tourmaline composite coating deposited by the present invention can protect the metal substrate from corrosion and extend the service life of the product. Description of the Drawings

[0050] Figure 1 Shows a schematic diagram of an electrophoretic deposition apparatus. Detailed Description of the Invention

[0051] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more distinct with these descriptions.

[0052] The first aspect of the present invention lies in providing an electrophoretic deposition method for a tourmaline composite coating, and the electrophoretic deposition method includes the following steps:

[0053] Step 1: Pretreat the metal. Mix a rare earth element-containing compound and ethanol to obtain a rare earth element-containing solution, coat the pretreated metal surface with the rare earth element-containing solution, and dry it to obtain a metal coated with rare earth elements.

[0054] Step 2: Add tourmaline, a dispersant, a surfactant, and a conductive salt to water, and then add a thermoelectric material, a rare earth element-containing compound, and a metal oxide, and stir evenly to obtain an electrophoretic solution.

[0055] Step 3: Place the metal coated with rare earth elements in the electrophoretic solution for electrophoretic deposition.

[0056] Step 4: Dry the metal after electrophoretic deposition, then perform annealing treatment, and finally perform grinding and polishing to obtain a tourmaline composite coating deposited on the metal surface.

[0057] The above steps will be specifically described below.

[0058] In Step 1, the metal includes aluminum, copper, iron, and stainless steel.

[0059] The pretreatment includes: successively cleaning, degreasing, and grinding the metal.

[0060] The cleaning includes: wiping the metal surface with acetone to remove impurities such as oil and dust on the metal surface. Ensure that the metal surface is clean and tidy, providing a good foundation for subsequent treatment.

[0061] The degreasing includes: soaking the metal in a 5-15% sodium hydroxide solution for 10-20 minutes.

[0062] Preferably, the degreasing includes: soaking the metal in a 10% sodium hydroxide solution for 15 minutes to remove the grease on the metal surface. Then rinse it thoroughly with deionized water to avoid residual sodium hydroxide solution.

[0063] The grinding includes: grinding the metal surface with sandpaper to make its surface roughness reach 3 - 5 μm. Pay attention to uniform grinding during the grinding process to avoid local over - grinding or under - grinding.

[0064] Mix a compound containing rare earth elements and ethanol to obtain a solution containing rare earth elements. The mass fraction of the solution containing rare earth elements is 0.05 - 0.2%, preferably 0.1%.

[0065] The compound containing rare earth elements is preferably CeO2. The particle size of CeO2 is 5 - 10 nm.

[0066] The coating is preferably spin - coating.

[0067] The drying conditions are: drying at 50 - 70 °C for 5 - 15 min.

[0068] Preferably, the drying conditions are: drying at 60 °C for 10 min. Forming a CeO2 interface layer on the metal surface can enhance the adhesion of the subsequent film layer.

[0069] The present invention uses a gradient deposition method to deposit on the metal surface. In the present invention, CeO2 is spin - coated on the bottom layer, which can not only enhance the adhesion of the subsequent film layer, but also enhance catalysis. Tourmaline is deposited on the surface of CeO2 by electrophoretic deposition. Tourmaline can directly release negative ions and emit far - infrared radiation, improving the environmental friendliness and environmental protection and health value of the product.

[0070] In step 2, the thermoelectric material is selected from one or more of BaTiO3, ZnO, and PVDF (polyvinylidene fluoride).

[0071] Preferably, the thermoelectric material is BaTiO3. The piezoelectricity of BaTiO3 can induce a local electric field and promote the charge separation on the surface of CeO2.

[0072] The present invention selects natural tourmaline and grinds the tourmaline. The particle size of the ground tourmaline is 1 - 5 μm, preferably ground to 1 - 3 μm. To ensure the purity and performance of the tourmaline, particles that are too large or too small are removed by screening to ensure uniform particle size.

[0073] Tourmaline naturally releases negative ions, and the porous / nanostructure increases the specific surface area, promoting electron migration and surface reactions.

[0074] The compound containing rare earth elements is selected from one or more of cerium - containing compounds.

[0075] Preferably, the compound containing rare earth elements is cerium dioxide (CeO2), and the particle size of the cerium dioxide is 5 - 15 nm. Small - particle - size cerium dioxide can provide more active sites.

[0076] In the electrophoretic deposition method of the present invention, a compound containing rare earth elements is added. This can not only enhance the piezoelectric properties of the tourmaline composite coating, but also adjust the carrier concentration, thereby optimizing the thermoelectric properties. Preferably, in the present invention, by adding a cerium-containing compound such as cerium dioxide, due to its high oxygen vacancy concentration, catalytic activity, and electron mobility characteristics, the negative ion release efficiency and the stability of the tourmaline composite coating material can be improved.

[0077] The cerium dioxide (CeO2) added in the present invention has the following mechanism of action: (1) Catalytic enhancement: The oxygen vacancies of CeO2 can adsorb H2O / O2 molecules in the air. CeO2 catalyzes the decomposition of H2O into ·OH, accelerating the generation of surface hydroxyl radicals (·OH), promoting the release of negative ions, and synergistically increasing the negative ion concentration with the O2 released by tourmaline. (2) Electron regulation: The Ce / Ce redox pair can increase the carrier concentration, enhancing the synergistic effect of the piezoelectric / thermoelectric effect and negative ion generation. (3) Structural stability: CeO2 nanoparticles can inhibit the excessive growth of grains, improving the densification and adhesion of the metal surface film layer. - 3+ / Ce 4+

[0078] The metal oxide is selected from one or more of zinc oxide, manganese oxide, and titanium dioxide.

[0079] Preferably, the metal oxide is titanium dioxide (TiO2). TiO2 can photocatalytically generate reactive oxygen species.

[0080] The dispersant is selected from one or more of sodium citrate, polyethylene glycol, triethylhexyl phosphate, sodium dodecyl sulfate, methyl pentanol, cellulose derivatives, and ammonium polyacrylate. Preferably, the dispersant is sodium citrate. It has a good dispersion effect and can effectively prevent the aggregation of tourmaline particles. At the same time, sodium citrate can chelate Ce, preventing particle aggregation and making the tourmaline in the electrophoretic solution more evenly dispersed. 3+

[0081] The surfactant is selected from one or more of sodium linear alkylbenzene sulfonate, α-olefin sulfonate, and stearic acid. Preferably, the surfactant is sodium dodecyl sulfate (SDS). It helps to improve the dispersion and stability of tourmaline particles in the solution.

[0082] The conductive salt is selected from one of sodium chloride (NaCl) and potassium chloride. Preferably, the conductive salt is sodium chloride. The conductive salt provides ionic conductivity for the electrophoretic deposition process.

[0083] The mass ratio of the tourmaline, dispersant, surfactant, and conductive salt is 2 - 6:1 - 3:0.5 - 2:0.2 - 0.5. ​​​

[0084] Preferably, the mass ratio of tourmaline, dispersant, surfactant and conductive salt is 4:2:1:0.3.

[0085] Based on the total mass of tourmaline, dispersant, surfactant and conductive salt being 100%, the addition amount of the rare earth element-containing compound is 5-25 wt%, preferably 15 wt%.

[0086] If the addition amount of the rare earth element-containing compound exceeds 25%, it is likely to cause an increase in the resistance of the tourmaline film layer.

[0087] Based on the total mass of tourmaline, dispersant, surfactant and conductive salt being 100%, the addition amount of the thermoelectric material is 15-30%, preferably 20%.

[0088] Based on the total mass of tourmaline, dispersant, surfactant and conductive salt being 100%, the addition amount of metal oxide is 5-15%, preferably 10%.

[0089] The addition amount of water is not particularly limited as long as it can completely dissolve tourmaline, dispersant, surfactant and conductive salt.

[0090] The rotation speed of the stirring is 300-500 r / min, and the stirring time is 30-60 min.

[0091] Preferably, the rotation speed of the stirring is 400 r / min, and the stirring time is 45 min. During the stirring process, a magnetic stirrer can be used to fully dissolve each component, ensure that tourmaline particles are evenly dispersed in the solution to form a stable electrophoretic solution, and also promote the uniform dispersion of CeO2.

[0092] In step 3, the conditions for electrophoretic deposition are: the voltage is increased to the electrophoretic deposition voltage at a boosting speed of 3-7 V / s, the electrophoretic deposition voltage is 30-60 V, the current is 0.1-0.5 A, and the electrophoretic deposition time is 8-20 min.

[0093] Preferably, the conditions for electrophoretic deposition are: the voltage is increased to the electrophoretic deposition voltage at a boosting speed of 5 V / s, the electrophoretic deposition voltage is 40-50 V, the current is 0.2-0.3 A, and the electrophoretic deposition time is 10-15 min.

[0094] The boosting speed described in the present invention can reduce the agglomeration of CeO2 and improve the dispersibility and stability of particles in the electrophoretic solution. The above deposition time can increase the penetration amount of CeO2.

[0095] The electrophoretic deposition is carried out in an electrophoretic deposition device, and the electrophoretic deposition device is as Figure 1As shown in the figure, it includes an electrophoresis tank, a positive power terminal, a negative power terminal, a metal, a fixture, a stirring device, a motor, and a stirring paddle.

[0096] The electrophoresis tank is a container for holding the electrophoresis solution and placing the metal workpiece to be coated. It is in the shape of a cuboid and is made of a plastic material with good corrosion resistance. There is enough space inside for placing the workpiece and containing the electrophoresis solution. A positive power terminal is provided on one side of the electrophoresis tank, and a negative power terminal is provided on the opposite side for connecting to an external power source to provide a DC electric field for the electrophoresis deposition process. The metal to be coated is fixed in place by a fixture and suspended in the electrophoresis solution in the electrophoresis tank. The fixture is made of an insulating material to avoid conduction and affect the electrophoresis effect. At the same time, a stirring device is provided at the bottom of the electrophoresis tank. The stirring device is driven by a motor, and the stirring paddle is located at the bottom of the electrophoresis tank. It can uniformly stir the electrophoresis solution during electrophoresis to ensure that the tourmaline particles are evenly dispersed in the electrophoresis solution, prevent them from precipitating, and ensure the uniformity of the deposition process.

[0097] During the electrophoresis deposition process, the tourmaline particles migrate and deposit on the metal surface under the action of the electric field. Preferably, to ensure the uniform deposition of the tourmaline particles, the electrophoresis solution can be stirred by controlling the stirring device, and the stirring speed is controlled at 150 - 300 r / min, and the preferred stirring speed is 200 r / min. The above stirring speed can also promote the uniform dispersion of CeO2.

[0098] In step 4, after the electrophoresis deposition is completed, the metal is taken out of the electrophoresis solution and the surface is rinsed with deionized water to remove the residual electrophoresis solution.

[0099] Then the metal is placed in an oven for drying. The drying temperature is 70 - 90°C, and the drying time is 1 - 3 h.

[0100] Preferably, the drying temperature is 80 - 90°C, and the drying time is 1 - 2 h. Through the drying treatment of the present invention, the tourmaline composite coating can be cured, improving the stability of the coating and its adhesion on the metal surface.

[0101] After drying, an annealing treatment is carried out. The present invention adopts a two-step annealing method for the annealing treatment.

[0102] The annealing treatment includes: heating up at a heating rate of 3 - 6°C / min to 250 - 350°C, and holding at this temperature for 20 - 45 min to remove organic substances. Subsequently, heating up at a heating rate of 3 - 6°C / min to 500 - 600°C, and holding at this temperature for 1 - 3 h. The high-temperature annealing treatment can promote the reaction between CeO2 and the substrate to form a Ce - O - M bond, making the combination of CeO2 and the substrate closer. The heating rate should not be too fast. The heating rate range disclosed in the present invention can prevent the coarsening of CeO2 grains.

[0103] Preferably, the annealing treatment includes: heating up to 300 °C at a heating rate of 5 °C / min, holding at this temperature for 30 min to remove organic substances, and then heating up to 550 °C at a heating rate of 5 °C / min and holding at this temperature for 2 h.

[0104] The grinding includes: using sandpaper to grind the surface of the coating to remove the rough and uneven parts on the surface, making the surface of the coating smoother. Pay attention to the appropriate force during the grinding process to avoid damaging the tourmaline composite coating.

[0105] The polishing includes: using a polishing machine to polish the surface of the tourmaline composite coating to further improve the gloss and smoothness of the coating surface. A polishing paste can be used during the polishing process to achieve a better polishing effect.

[0106] The second aspect of the present invention lies in providing a tourmaline composite coating deposited on a metal surface by the electrophoretic deposition method according to the first aspect of the present invention.

[0107] Examples

[0108] The present invention is further illustrated below by specific examples. These examples are only for illustrating the present invention and are not used to limit the scope of the present invention. The raw materials used in the examples of the present invention are all commercially available.

[0109] Example 1

[0110] Pretreat the metal: wipe the surface of the stainless steel with acetone to remove impurities such as oil and dust on the surface of the stainless steel. Then soak the stainless steel in a 10% sodium hydroxide solution for 15 min to remove the grease on the surface of the stainless steel. Subsequently, use sandpaper to grind the surface of the stainless steel to make its surface roughness reach 3 - 5 μm.

[0111] Mix CeO2 and ethanol to obtain a solution containing rare earth elements. The mass fraction of the solution containing rare earth elements is 0.1%. Spin - coat the solution containing rare earth elements on the pretreated metal surface, and then dry at 60 °C for 10 min.

[0112] Natural tourmaline is selected and ground. To ensure the purity and performance of tourmaline, particles that are too large or too small are removed by screening. The particle size of the ground tourmaline is 1 - 5 μm. The ground tourmaline, sodium citrate, sodium dodecyl sulfate, and sodium chloride are mixed in a mass ratio of 4:2:1:0.3, and then added to water. Subsequently, cerium dioxide, titanium dioxide, and BaTiO3 (barium titanate) with a particle size of 5 - 15 nm are added. Based on the total mass of tourmaline, dispersant, surfactant, and conductive salt being 100%, the addition amount of cerium dioxide is 15 wt%, the addition amount of titanium dioxide is 10%, and the addition amount of BaTiO3 is 20%. Stir evenly at a stirring speed of 400 r / min for 45 min to fully dissolve each component and ensure that the tourmaline particles are evenly dispersed in the solution, thus obtaining a stable electrophoresis solution.

[0113] The pretreated stainless steel is placed in the electrophoresis solution for electrophoretic deposition. The electrophoretic deposition is carried out in an electrophoresis tank. The conditions for electrophoretic deposition are as follows: The voltage is increased to the electrophoretic deposition voltage at a boosting speed of 5 V / s. The electrophoretic deposition voltage is 45 V, the current is 0.3 A, and the electrophoretic deposition time is 15 min. During the electrophoretic deposition process, to ensure the uniform deposition of tourmaline particles, the electrophoresis solution can be stirred by controlling a stirring device, and the stirring speed is controlled at 200 r / min.

[0114] After the electrophoretic deposition is completed, the stainless steel is taken out of the electrophoresis solution and the surface is rinsed with deionized water to remove the residual electrophoresis solution. Then the stainless steel is placed in an oven for drying. The drying temperature is 85°C and the drying time is 1.5 h. After drying, annealing treatment is carried out. The annealing treatment includes: heating to 300°C at a heating rate of 5°C / min and holding at this temperature for 30 min to remove organic substances. Subsequently, heating to 550°C at a heating rate of 5°C / min and holding at this temperature for 2 h. Finally, the surface of the coating is polished with sandpaper to remove the rough and uneven parts on the surface, making the surface of the coating smoother. Finally, the surface of the tourmaline composite coating is polished with a polishing machine to further improve the gloss and smoothness of the coating surface, obtaining a tourmaline composite coating deposited on the metal surface.

[0115] Microscopic tests are carried out on the surface of the stainless steel before and after pretreatment in Example 1. The test results show that: on the surface of the stainless steel without pretreatment, the surface is relatively flat and smooth, with only a small amount of minute undulations caused by processing marks, etc., which is microscopically not conducive to the firm adhesion of the subsequent coating. On the surface of the stainless steel pretreated by the pretreatment (cleaning, degreasing, polishing) described in the present invention, it can be clearly seen that the surface roughness has increased significantly, with many minute concave and convex structures. These structures create good conditions for the subsequent tourmaline composite coating to firmly adhere to the stainless steel substrate by means of mechanical interlocking, etc., and help to improve the bonding force between the tourmaline composite coating and the metal substrate.

[0116] The XRD test was carried out on the tourmaline composite coating. After testing, CeO2 in the tourmaline composite coating was evenly distributed in the cubic fluorite structure without impurity phases.

[0117] The SEM test was carried out on the tourmaline composite coating of Example 1. After testing, the porosity of the tourmaline composite coating of Example 1 was reduced to 15%, indicating that the CeO2 particles added in the present invention helped to reduce the porosity of the coating and improve the density of the tourmaline composite coating.

[0118] Example 2

[0119] Pretreat the metal: Wipe the surface of the aluminum metal with acetone to remove impurities such as oil and dust on the surface of the aluminum metal. Then soak the aluminum metal in a 5% sodium hydroxide solution for 20 min to remove the grease on the surface of the aluminum metal. Subsequently, polish the surface of the aluminum metal with sandpaper to make its surface roughness reach 3 - 5 μm.

[0120] Mix CeO2 and ethanol to obtain a solution containing rare earth elements. The mass fraction of the solution containing rare earth elements is 0.05%. Spin - coat the solution containing rare earth elements on the pretreated metal surface, and then dry it at 50 °C for 15 min.

[0121] Select natural tourmaline and grind the tourmaline. The particle size of the ground tourmaline is 1 - 5 μm. To ensure the purity and performance of the tourmaline, remove too large or too small particles by screening. Mix the ground tourmaline, sodium citrate, sodium dodecyl sulfate, and sodium chloride according to a mass ratio of 2:1:0.5:0.2. Then add them to water, and then add cerium dioxide, titanium dioxide, and BaTiO3 with a particle size of 5 - 15 nm. Based on the mass of tourmaline, dispersant, surfactant, and conductive salt being 100%, the addition amount of cerium dioxide is 5 wt%, the addition amount of titanium dioxide is 5%, and the addition amount of BaTiO3 is 15%. Stir evenly at a stirring speed of 300 r / min for 60 min. Make each component fully dissolve to ensure that the tourmaline particles are evenly dispersed in the solution, and a stable electrophoresis solution is prepared.

[0122] Place the pretreated aluminum metal in the electrophoresis solution for electrophoresis deposition. The electrophoresis deposition is carried out in an electrophoresis tank. The conditions for electrophoresis deposition are: increase the voltage to the electrophoresis deposition voltage at a boosting speed of 5 V / s. The electrophoresis deposition voltage is 40 V, the current is 0.3 A, and the electrophoresis deposition time is 12 min. During the electrophoresis deposition process, to ensure the uniform deposition of tourmaline particles, the electrophoresis solution can be stirred by controlling the stirring device, and the stirring speed is controlled at 150 r / min.

[0123] After the electrophoretic deposition is completed, the aluminum metal is taken out of the electrophoretic solution, and its surface is rinsed with deionized water to remove the residual electrophoretic solution. Then the aluminum metal is placed in an oven for drying. The drying temperature is 80 °C and the drying time is 2 h. After drying, annealing treatment is carried out. The annealing treatment includes: heating up to 250 °C at a heating rate of 5 °C / min, holding at this temperature for 45 min to remove organic substances, and then heating up to 500 °C at a heating rate of 5 °C / min and holding at this temperature for 3 h. Finally, the surface of the coating is polished with sandpaper to remove the rough and uneven parts, making the surface of the coating smoother. Finally, the surface of the tourmaline composite coating is polished with a polishing machine to further improve the gloss and smoothness of the coating surface, and the tourmaline composite coating deposited on the aluminum metal surface is obtained.

[0124] Example 3

[0125] Pretreat the metal: Wipe the surface of the copper metal with acetone to remove impurities such as oil and dust on the surface of the copper metal. Then immerse the copper metal in a 15% sodium hydroxide solution for 10 min to remove the grease on the surface of the copper metal. Subsequently, the surface of the copper metal is polished with sandpaper to make its surface roughness reach 3 - 5 μm.

[0126] Mix CeO2 and ethanol to obtain a solution containing rare earth elements. The mass fraction of the solution containing rare earth elements is 0.2%. Spin-coat the solution containing rare earth elements on the surface of the pretreated metal, and then dry it at 70 °C for 5 min.

[0127] Select natural tourmaline and grind the tourmaline. The particle size of the ground tourmaline is 1 - 5 μm. To ensure the purity and performance of the tourmaline, particles that are too large or too small are removed by screening. Mix the ground tourmaline, polyethylene glycol, sodium dodecyl sulfate, and sodium chloride in a mass ratio of 6:3:2:0.5. Then add it to water, and then add cerium dioxide, titanium dioxide, and BaTiO3 with a particle size of 5 - 15 nm. Based on the mass of tourmaline, dispersant, surfactant, and conductive salt being 100%, the addition amount of cerium dioxide is 25 wt%, the addition amount of titanium dioxide is 15%, and the addition amount of BaTiO3 is 30%. Stir evenly. The stirring speed is 500 r / min and the stirring time is 30 min. Make each component fully dissolve to ensure that the tourmaline particles are evenly dispersed in the solution, and a stable electrophoretic solution is prepared.

[0128] The pre-treated copper metal is placed in an electrophoresis solution for electrophoretic deposition. The electrophoretic deposition is carried out in an electrophoresis tank. The conditions for the electrophoretic deposition are as follows: the voltage is increased to the electrophoretic deposition voltage at a rate of 5 V / s. The electrophoretic deposition voltage is 50 V, the current is 0.2 A, and the electrophoretic deposition time is 10 min. During the electrophoretic deposition process, to ensure the uniform deposition of tourmaline particles, the electrophoresis solution can be stirred by controlling a stirring device, and the stirring speed is controlled at 300 r / min.

[0129] After the electrophoretic deposition is completed, the copper metal is taken out of the electrophoresis solution, and the surface is rinsed with deionized water to remove the residual electrophoresis solution. Then the copper metal is placed in an oven for drying. The drying temperature is 90 °C, and the drying time is 1 h. After drying, annealing treatment is carried out. The annealing treatment includes: heating at a rate of 5 °C / min to 350 °C and holding at this temperature for 20 min to remove organic substances. Subsequently, heating at a rate of 5 °C / min to 600 °C and holding at this temperature for 1 h. Finally, the surface of the coating is polished with sandpaper to remove the rough and uneven parts on the surface, making the surface of the coating smoother. Finally, the surface of the tourmaline composite coating is polished by a polishing machine to further improve the gloss and smoothness of the coating surface, and a tourmaline composite coating deposited on the copper metal surface is obtained.

[0130] Comparative Example 1

[0131] The deposition of the tourmaline composite coating is carried out in a manner similar to that in Example 1, with the only difference being that CeO2 is not spin-coated on the metal surface, nor is CeO2 added to the electrophoresis solution.

[0132] The negative ion concentration of Example 1 and Comparative Example 1 is tested, and it is obtained that the negative ion concentration of Example 1 is 8000 ions / cm 3 , which is 60% higher than that of Comparative Example 1.

[0133] The piezoelectric coefficient and thermoelectric power factor of the composite coatings prepared in Example 1 and Comparative Example 1 are tested respectively. It is measured that the piezoelectric coefficient of the composite coating prepared in Example 1 reaches 650 pC / N, which is 8% higher than that of Comparative Example 1; the thermoelectric power factor of the composite coating prepared in Example 1 is 2.5 μW / (m·K 2 ), which is 15% higher than that of Comparative Example 1.

[0134] Experimental Example

[0135] Experimental Example 1

[0136] The profile of the deposition of tourmaline particles during the electrophoretic deposition process in Example 1 was tested. The test results showed the deposition of tourmaline particles on the stainless-steel surface during the electrophoretic deposition process. It can be seen that after the power was turned on, the tourmaline particles in the electrophoretic solution moved directionally towards the metal surface, which was one of the electrodes, gradually approached and adhered to its surface. As time passed, they continuously accumulated to form a continuous tourmaline composite coating. And from the test results, it can be seen that due to the action of dispersants and surfactants in the electrophoretic solution, the tourmaline particles were relatively evenly distributed during the deposition process, avoiding the situation of over-dense or over-sparse local particle accumulation, and ensuring the uniformity of the overall performance of the coating.

[0137] Experimental Example 2

[0138] The appearance of the metal surface coated with the tourmaline composite coating in Example 1 was tested. The test results showed the appearance of the stainless-steel surface after depositing the tourmaline composite coating by the electrophoretic deposition method described in the present invention. From the test results, it can be seen that the stainless-steel surface was entirely covered with a uniform tourmaline composite coating. The tourmaline composite coating had a flat appearance and uniform color, without obvious defects such as bubbles and peeling, showing a good coating effect, indicating that the tourmaline composite coating could better exert the functional characteristics of tourmaline, such as releasing negative ions and far-infrared radiation.

[0139] Experimental Example 3

[0140] After the electrophoretic deposition in Example 1 was completed, the microstructure of the surface of the tourmaline composite coating after post-treatment was tested. The test results showed the microstructure of the surface of the tourmaline composite coating after the post-treatment (grinding and polishing) steps described in the present invention. The test results showed that the surface of the tourmaline composite coating became smoother and denser after grinding and polishing. Microscopically, some originally possible fine particle protrusions became flatter. This not only improved the appearance quality of the tourmaline composite coating, giving it a better gloss, but also from a functional perspective, it helped to better protect the tourmaline particles inside the coating, enabling them to more stably and durably exert their corresponding functions, and further improving the quality and service performance of the entire metal product with the deposited tourmaline composite coating.

[0141] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. An electrophoretic deposition method for a tourmaline composite coating, characterized in that, The electrophoretic deposition method includes the following steps: Step 1: Pretreat the metal. Mix a compound containing rare earth elements and ethanol to obtain a solution containing rare earth elements. Coat the solution containing rare earth elements on the surface of the pretreated metal and dry it to obtain a metal coated with rare earth elements. Step 2: Add tourmaline, dispersant, surfactant, and conductive salt to water, then add thermoelectric material, compound containing rare earth elements, and metal oxide, and stir evenly to obtain an electrophoretic solution. Step 3: Place the metal coated with rare earth elements in the electrophoretic solution for electrophoretic deposition. Step 4: Dry the metal after electrophoretic deposition, then perform annealing treatment, and finally polish and buff it to obtain a tourmaline composite coating deposited on the metal surface.

2. The electrophoretic deposition method according to claim 1, wherein In Step 1, The pretreatment includes: cleaning, degreasing, and polishing the metal in sequence. The cleaning includes: wiping the metal surface with acetone. The degreasing includes: soaking the metal in a 5 - 15% sodium hydroxide solution for 10 - 20 minutes. The polishing includes: polishing until the surface roughness of the metal reaches 3 - 5 μm.

3. The electrophoretic deposition method according to claim 1, characterized in that, In Step 1, The mass fraction of the solution containing rare earth elements is 0.05 - 0.2%; and / or, The drying conditions are: drying at 50 - 70°C for 5 - 15 minutes.

4. The electrophoretic deposition method according to claim 1, wherein In Step 2, The dispersant is selected from one or more of sodium citrate, polyethylene glycol, triethylhexyl phosphate, sodium dodecyl sulfate, methyl pentanol, cellulose derivatives, and ammonium polyacrylate; and / or, The surfactant is selected from one or more of linear alkylbenzene sulfonate, α - olefin sulfonate, and stearic acid; and / or, The conductive salt is selected from one of sodium chloride and potassium chloride; and / or, The mass ratio of tourmaline, dispersant, surfactant, and conductive salt is 2 - 6:1 - 3:0.5 - 2:0.2 - 0.

5.

5. The electrophoretic deposition method according to claim 1, wherein In Step 2, The thermoelectric material is selected from one or more of BaTiO3, ZnO, and PVDF; Based on the total mass of tourmaline, dispersant, surfactant, and conductive salt being 100%, the addition amount of the thermoelectric material is 15 - 30%.

6. The electrophoretic deposition method according to claim 1, characterized in that, In Step 2, The compound containing rare earth elements is cerium dioxide, and the particle size of the cerium dioxide is 5 - 15 nm; Based on the total mass of tourmaline, dispersant, surfactant, and conductive salt being 100%, the addition amount of the compound containing rare earth elements is 5 - 25 wt%.

7. The electrophoretic deposition method according to claim 1, wherein In Step 2, The metal oxide is selected from one or more of zinc oxide, manganese oxide, and titanium dioxide; Based on the total mass of tourmaline, dispersant, surfactant, and conductive salt being 100%, the addition amount of the metal oxide is 5 - 15%.

8. The electrophoretic deposition method according to claim 1, wherein In Step 3, The conditions for electrophoretic deposition are: increasing the voltage to the electrophoretic deposition voltage at a rising rate of 3 - 7 V / s, the electrophoretic deposition voltage is 30 - 60 V, the current is 0.1 - 0.5 A, and the electrophoretic deposition time is 8 - 20 minutes.

9. The electrophoretic deposition method according to claim 1, wherein In Step 4, The drying temperature is 70 - 90°C, and the drying time is 1 - 3 h; and / or, The annealing treatment includes: heating to 250 - 350°C at a heating rate of 3 - 6°C / min, holding at this temperature for 20 - 45 min, then heating to 500 - 600°C at a heating rate of 3 - 6°C / min, and holding at this temperature for 1 - 3 h.

10. A tourmaline composite coating deposited by the electrophoretic deposition method according to any one of claims 1 to 9.

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