A polyaniline-carboxymethyl chitosan-modified boron nitride composite material and a preparation method thereof

Abstract

The application belongs to the technical field of metal material corrosion and protection, and provides a polyaniline-carboxymethyl chitosan-modified boron nitride composite material and a preparation method thereof. Hexagonal boron nitride is first added into a sodium hydroxide aqueous solution, washed, dried, and then ultrasonically dispersed in isopropyl alcohol to obtain modified boron nitride. Then, aniline, carboxymethyl chitosan and boron nitride are dissolved in an inorganic acid solution to obtain a reaction solution. Finally, the reaction solution is used as a deposition liquid, and metal is used as a to-be-electroplated base layer, and a polyaniline-carboxymethyl chitosan-modified boron nitride composite material is prepared on the metal surface by using an electrodeposition method. Because the molecular chain of carboxymethyl chitosan can rotate freely, is flexible, and contains a large number of -NH2, -OH and -COOH groups, the carboxymethyl chitosan can be used as an active site to react with polyaniline, so that the adhesion to the metal base layer and the corrosion protection effect are improved. Boron nitride is resistant to high temperature and has good barrier performance, so that the adhesion of the coating to the metal base is improved, and the protection of the metal is improved.

Description

Technical Field

[0001] This invention belongs to the field of metal material corrosion and protection technology, specifically relating to a polyaniline-carboxymethyl chitosan-modified boron nitride composite material and its preparation method. Background Technology

[0002] Stainless steel possesses excellent machinability, electrical conductivity, and thermal conductivity, making it widely used in industrial fields and daily life. However, its relatively reactive chemical properties make it prone to various corrosion phenomena in practical applications, leading to a reduction in its performance and limiting its applications. Currently, organic coatings are commonly used for the protection of stainless steel and other metals, among which conductive polymers have attracted considerable attention in recent years. Polyaniline...

[0003] PANI (polyaniline) is a low-cost conductive polymer with special redox properties and corrosion resistance. It can form a passivation film on metal surfaces to delay corrosion. However, due to the intermolecular hydrogen bonds between the aromatic rings and amine / imine groups of PANI, its solubility and mechanical properties are poor, limiting its applications. Therefore, there is an urgent need to develop a material that can improve the solubility and mechanical properties of PANI, while also possessing better corrosion resistance and adhesion. Summary of the Invention

[0004] This invention is made to solve the above-mentioned problems, and its purpose is to provide a polyaniline-carboxymethyl chitosan-modified boron nitride composite material and its preparation method.

[0005] This invention provides a method for preparing a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, comprising the following steps: Step S1, weighing a certain mass of hexagonal boron nitride and adding it to a sodium hydroxide solution of a certain concentration, grinding for a certain time, then washing and drying to obtain a dried modified boron nitride intermediate, dispersing the dried modified boron nitride intermediate in isopropanol and sonicating it to obtain a modified boron nitride solution; Step S2, weighing a certain mass of aniline, carboxymethyl chitosan and the modified boron nitride solution and dissolving them in an inorganic acid solution of a certain concentration, adjusting the pH value to 1-9 to obtain a reaction solution; Step S3, using the reaction solution as the deposition solution for electrochemical deposition, using a metal as the substrate to be electroplated, and performing electrochemical deposition on the metal using cyclic voltammetry to obtain the polyaniline-carboxymethyl chitosan-modified boron nitride composite material on the surface of the metal.

[0006] The preparation method of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material provided by the present invention may also have the following feature: wherein the mass ratio of modified boron nitride, carboxymethyl chitosan and aniline in the modified boron nitride solution is 1 to 5:10:23.

[0007] The preparation method of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material provided by the present invention may also have the following feature: wherein the concentration of the sodium hydroxide solution is 0.1 mol / L to 3 mol / L.

[0008] The preparation method of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material provided by the present invention may also have the following characteristics: wherein the inorganic acid in the inorganic acid solution is any one of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid; and the concentration of the inorganic acid solution is 0.1 mol / L to 3 mol / L.

[0009] The preparation method of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material provided by the present invention may also have the following feature: wherein, in step S3, the voltage of the cyclic voltammetry is -0.3V to 1.5V.

[0010] The present invention also provides a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, which is prepared by the method for preparing polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0011] The role and effect of invention

[0012] According to the polyaniline-carboxymethyl chitosan-modified boron nitride composite material and its preparation method, polyaniline, containing a benzene ring structure, has a rigid structure, making its molecular chains difficult to rotate and resulting in poor solubility. This leads to weak adhesion and poor corrosion protection when polyaniline is used as a protective coating for a metal substrate. In contrast, carboxymethyl chitosan's molecular chains can rotate freely and contain a large number of -NH2, -OH, and -COOH groups, which can act as active sites to react with polyaniline. The electrochemical combination of the two improves the solubility of polyaniline and enhances its adhesion to the metal substrate, thereby improving the corrosion protection effect. Furthermore, carboxymethyl chitosan itself is a good corrosion inhibitor and has viscosity, further improving the corrosion protection and adhesion.

[0013] Furthermore, boron nitride is a non-oxide ceramic material with advantages such as high temperature resistance and good barrier properties. It can be used as a coating to protect metal substrates, improve the mechanical properties of the coating, and enhance the adhesion of the coating to the metal substrate, thereby improving the protection of the metal. However, the covalent bonds between boron nitrides are strong, and the electrons in the structure are bound, lacking modifiable functional groups or active sites, resulting in poor dispersibility in aniline solutions. Therefore, by modifying boron nitride to increase its solubility in aniline solutions and increase the number of active sites, the polyaniline-carboxymethyl chitosan-boron nitride composite material can be better deposited on the metal surface, thus preparing a polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The prepared polyaniline-carboxymethyl chitosan-modified boron nitride composite material has good corrosion resistance and significantly improved adhesion to the metal surface.

[0014] Furthermore, the method of preparing polyaniline-carboxymethyl chitosan-modified boron nitride composite material on metal surface by electrochemical deposition is simple to operate and has a short synthesis time. Attached Figure Description

[0015] Figure 1 This is a comparison of the polarization curves of 304 stainless steel, polyaniline, polyaniline-carboxymethyl chitosan, and polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Examples 1-5 of this invention in 3.5wt% NaCl solution.

[0016] Figure 2 The images show a metallographic microscopy comparison of 304 stainless steel and 304 stainless steel after polarization testing, polyaniline, polyaniline-carboxymethyl chitosan, and the polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 of this invention; and...

[0017] Figure 3 This is a before-and-after comparison of the adhesion test results of polyaniline and the polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 of this invention. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easy to understand, the following describes in detail a polyaniline-carboxymethyl chitosan-modified boron nitride composite material and its preparation method, in conjunction with embodiments and accompanying drawings.

[0019] Unless otherwise specified, all raw materials and reagents used in this invention are from commercially available sources.

[0020] The present invention provides a method for preparing a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, comprising the following steps:

[0021] Step S1: Weigh 2g of hexagonal boron nitride and add it to a 0.1mol / L to 3mol / L sodium hydroxide solution. Ball mill the solution in a vertical planetary ball mill at a speed of 400r / min for 24h. Then wash and dry the solution to obtain the dried modified boron nitride intermediate. Take 0.5g of the dried modified boron nitride intermediate and disperse it in 500ml of isopropanol. Then sonicate the solution using a two-dimensional material stripper to obtain the modified boron nitride solution.

[0022] In this step, the concentration of the sodium hydroxide solution is 0.1 mol / L to 3 mol / L. In this invention, only an example with a sodium hydroxide solution concentration of 2 mol / L is used for illustration; however, a concentration of 0.1 mol / L to 3 mol / L can achieve the same technical effect.

[0023] Step S2: Weigh a certain mass of aniline and dissolve it in a 0.1 mol / L to 3 mol / L inorganic acid solution. Then, add a certain mass of carboxymethyl chitosan and the modified boron nitride solution prepared in step S1. Continue to add inorganic acid solution or alkaline solution to adjust the pH to 1 to 9. Stir magnetically at room temperature for 3 hours to obtain a reaction solution. The mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline in the weighed modified boron nitride solution is 1 to 5:10:23.

[0024] In this step, the mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline is 1 to 5:10:23. In this invention, only examples with mass ratios of 1:10:23, 3:10:23, and 5:10:23 are used for illustration; preferably, the mass ratio is 3:10:23.

[0025] In this step, the inorganic acid solution is selected from any one of hydrochloric acid solution, sulfuric acid solution, nitric acid solution, and phosphoric acid solution. In this invention, only the phosphoric acid solution in the examples is used for illustration, but any hydrochloric acid solution, sulfuric acid solution, or nitric acid solution can achieve the same technical effect. The concentration of the inorganic acid solution is 0.1 mol / L to 3 mol / L. In this invention, only the 1 mol / L inorganic acid in the examples is used for illustration, but inorganic acid solutions of 0.1 mol / L to 3 mol / L can achieve the same technical effect.

[0026] In this step, the solution pH ranges from 1 to 9. In this invention, only pH values ​​of 4, 6, and 8 are used for illustration, with pH 4 being the preferred value.

[0027] In step S3, the reaction solution is used as the deposition solution for electrochemical deposition, and the metal is used as the substrate to be electroplated. Using cyclic voltammetry, the voltage is set to -0.3V to 1.5V to perform electrochemical deposition on the metal, thereby obtaining the metal coated with polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The surface of the metal is the polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0028] In this step, the substrate layer to be electroplated is metal. This invention uses 304 stainless steel as an example, but other metals can achieve the same technical effect.

[0029] The voltage set for the cyclic voltammetry method is -0.3V to 1.5V. In this invention, only the voltage set in the embodiment is -0.2V to 1.2V for explanation. However, the same technical effect can be achieved by setting the voltage to -0.3V to 1.5V.

[0030] <Example 1>

[0031] In this embodiment, a polyaniline-carboxymethyl chitosan-modified boron nitride composite material was prepared using a mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline of 3:10:23.

[0032] Step S1: Weigh 2g of hexagonal boron nitride and add it to a 2mol / L sodium hydroxide solution. Ball mill the solution in a vertical planetary ball mill at a speed of 400r / min for 24h. Then wash and dry the solution to obtain the dried modified boron nitride intermediate. Take 0.5g of the dried modified boron nitride intermediate and disperse it in 500ml of isopropanol. Then sonicate the solution using a two-dimensional material stripper to obtain the modified boron nitride solution.

[0033] In step S2, 2.3g of aniline was weighed and dissolved in a 1mol / L phosphoric acid solution. Then, 1g of carboxymethyl chitosan and 30ml of the modified boron nitride solution prepared in step S1 were added. The pH was adjusted to 4 by adding more phosphoric acid solution. The mixture was then magnetically stirred at room temperature for 3 hours to obtain the reaction solution.

[0034] In step S3, the reaction solution prepared in step S2 is used as the deposition solution for electrochemical deposition. 304 stainless steel is used as the substrate to be electroplated. Using the cyclic voltammetry method, the voltage is set to -0.2 to 1.2V to perform electrochemical deposition on the 304 stainless steel, thereby obtaining 304 stainless steel coated with polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The surface of the 304 stainless steel is the polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0035] <Example 2>

[0036] This embodiment uses a mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline of 1:10:23 to prepare a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, specifically including the following steps:

[0037] Step S1: Weigh 2g of hexagonal boron nitride and add it to a 2mol / L sodium hydroxide solution. Ball mill the solution in a vertical planetary ball mill at a speed of 400r / min for 24h. Then wash and dry the solution to obtain the dried modified boron nitride intermediate. Take 0.5g of the dried modified boron nitride intermediate and disperse it in 500ml of isopropanol. Then sonicate the solution using a two-dimensional material stripper to obtain the modified boron nitride solution.

[0038] In step S2, 2.3g of aniline was weighed and dissolved in a 1mol / L phosphoric acid solution. Then, 1g of carboxymethyl chitosan and 10ml of the modified boron nitride solution prepared in step S1 were added. The pH was adjusted to 4 by adding more phosphoric acid solution. The mixture was then magnetically stirred at room temperature for 3 hours to obtain the reaction solution.

[0039] In step S3, the reaction solution prepared in step S2 is used as the deposition solution for electrochemical deposition. 304 stainless steel is used as the substrate to be electroplated. Using the cyclic voltammetry method, the voltage is set to -0.2 to 1.2V to perform electrochemical deposition on 304 stainless steel, thereby obtaining a polyaniline-carboxymethyl chitosan-modified boron nitride composite material coating 304 stainless steel. The surface of 304 stainless steel is the polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0040] <Example 3>

[0041] This embodiment uses a mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline of 5:10:23 to prepare a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, specifically including the following steps:

[0042] Step S1: Weigh 2g of hexagonal boron nitride and add it to a 2mol / L sodium hydroxide solution. Ball mill the solution in a vertical planetary ball mill at a speed of 400r / min for 24h. Then wash and dry the solution to obtain the dried modified boron nitride intermediate. Take 0.5g of the dried modified boron nitride intermediate and disperse it in 500ml of isopropanol. Then sonicate the solution using a two-dimensional material stripper to obtain the modified boron nitride solution.

[0043] In step S2, 2.3g of aniline was weighed and dissolved in a 1mol / L phosphoric acid solution. Then, 1g of carboxymethyl chitosan and 50ml of the modified boron nitride solution prepared in step S1 were added. The pH was adjusted to 4 by adding more phosphoric acid solution. The mixture was then magnetically stirred at room temperature for 3 hours to obtain the reaction solution.

[0044] In step S3, the reaction solution prepared in step S2 is used as the deposition solution for electrochemical deposition. 304 stainless steel is used as the substrate to be electroplated. Using the cyclic voltammetry method, the voltage is set to -0.2 to 1.2V to perform electrochemical deposition on the 304 stainless steel, thereby obtaining 304 stainless steel coated with polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The surface of the 304 stainless steel is the polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0045] <Example 4>

[0046] This embodiment uses a mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline of 3:10:23 to prepare a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, specifically including the following steps:

[0047] Step S1: Weigh 2g of hexagonal boron nitride and add it to a 2mol / L sodium hydroxide solution. Ball mill the solution in a vertical planetary ball mill at a speed of 400r / min for 24h. Then wash and dry the solution to obtain the dried modified boron nitride intermediate. Take 0.5g of the dried modified boron nitride intermediate and disperse it in 500ml of isopropanol. Then sonicate the solution using a two-dimensional material stripper to obtain the modified boron nitride solution.

[0048] In step S2, 2.3g of aniline was weighed and dissolved in a 1mol / L phosphoric acid solution. Then, 1g of carboxymethyl chitosan and 30ml of the modified boron nitride solution prepared in step S1 were added. The pH was adjusted to 6 by adding more phosphoric acid solution. The mixture was then magnetically stirred at room temperature for 3 hours to obtain the reaction solution.

[0049] In step S3, the reaction solution prepared in step S2 is used as the deposition solution for electrochemical deposition. 304 stainless steel is used as the substrate to be electroplated. Using the cyclic voltammetry method, the voltage is set to -0.2 to 1.2V to perform electrochemical deposition on the 304 stainless steel, thereby obtaining 304 stainless steel coated with polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The surface of the 304 stainless steel is the polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0050] <Example 5>

[0051] This embodiment uses a mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline of 3:10:23 to prepare a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, specifically including the following steps:

[0052] Step S1: Weigh 2g of hexagonal boron nitride and add it to a 2mol / L sodium hydroxide solution. Ball mill the solution in a vertical planetary ball mill at a speed of 400r / min for 24h. Then wash and dry the solution to obtain the dried modified boron nitride intermediate. Take 0.5g of the dried modified boron nitride intermediate and disperse it in 500ml of isopropanol. Then sonicate the solution using a two-dimensional material stripper to obtain the modified boron nitride solution.

[0053] In step S2, 2.3g of aniline was weighed and dissolved in a 1mol / L phosphoric acid solution. Then, 1g of carboxymethyl chitosan and 30ml of the modified boron nitride solution prepared in step S1 were added. The pH was adjusted to 8 by adding more phosphoric acid solution. The mixture was then magnetically stirred at room temperature for 3 hours to obtain the reaction solution.

[0054] In step S3, the reaction solution prepared in step S2 is used as the deposition solution for electrochemical deposition. 304 stainless steel is used as the substrate to be electroplated. Using the cyclic voltammetry method, the voltage is set to -0.2 to 1.2V to perform electrochemical deposition on the 304 stainless steel, thereby obtaining 304 stainless steel coated with polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The surface of the 304 stainless steel is the polyaniline-carboxymethyl chitosan-modified boron nitride composite material.

[0055] <Test Example>

[0056] Blank 304 stainless steel (in) Figure 1 a) and in this test example, referred to as 304 stainless steel, 304 stainless steel coated with polyaniline (in Figure 1 a) and 304 stainless steel coated with polyaniline-carboxymethyl chitosan composite material (in this test example) Figure 1 a) and in this test example, referred to as polyaniline-carboxymethyl chitosan; and the 304 stainless steel coated with the polyaniline-carboxymethyl chitosan-modified boron nitride composite material prepared in Examples 1-5. Figure 1 Using polyaniline-carboxymethyl chitosan-modified boron nitride (referred to as polyaniline-carboxymethyl chitosan-modified boron nitride in this test example) as the working electrode, a platinum electrode as the auxiliary electrode, and a silver / silver chloride (Ag / AgCl) electrode as the reference electrode, a three-electrode system was formed. Polarization curves were measured in 3.5 wt% NaCl solution at a scan rate of 1 mV / s. The results are shown in […]. Figure 1 .

[0057] Figure 1 (a) is a comparison of the polarization curves of 304 stainless steel, polyaniline, polyaniline-carboxymethyl chitosan, and polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 in NaCl solution. Figure 1 (b) is a comparison of the polarization curves of polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Examples 1-5 in NaCl solution.

[0058] The equipment used for polarization curve determination in this step is the Shanghai Chenhua Electrochemical Workstation CHI660C. The corresponding corrosion potential and corrosion current density are shown in the table below.

[0059] Figure 1 Electrochemical parameters of each sample obtained in 3.5 wt% NaCl aqueous solution

[0060]

[0061]

[0062] As shown in the table above, compared with blank 304 stainless steel and 304 stainless steel coated with polyaniline and polyaniline-carboxymethyl chitosan, the corrosion potential (E) of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material is significantly lower. corr The significant positive shift indicates that the polyaniline-carboxymethyl chitosan-modified boron nitride composite exhibits better stability in corrosive environments. This demonstrates that the addition of modified boron nitride and carboxymethyl chitosan significantly reduces the corrosion current density of the sample, enhancing the corrosion resistance of the stainless steel substrate in solution.

[0063] The protective efficiency (η%) of the coating is calculated according to the following formula:

[0064]

[0065] I0 and I represent the corrosion current densities of blank 304 stainless steel and 304 stainless steel coated with various materials, respectively. The corrosion current density of the blank 304 stainless steel sample is 9.6 × 10⁻⁶. -6 A / cm 2 When the mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline is 3:10:23 and the solution pH is 4, the corrosion current density will be 1.11 × 10⁻⁶. -7 A / cm 2 The protection efficiency reached as high as 98.9%. The results showed that the polyaniline-carboxymethyl chitosan-modified boron nitride composite material exhibited the best protective performance for 304 stainless steel substrates when the mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline was 3:10:23, thus enhancing the corrosion resistance of the stainless steel substrates in solution. Furthermore, a solution pH of 4 further improved the enhanced corrosion resistance of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material on the stainless steel substrates in solution.

[0066] 304 stainless steel, 304 stainless steel after polarization testing, polyaniline, polyaniline-carboxymethyl chitosan, and the polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 were examined using a metallographic microscope. The results are shown in [Figure 1]. Figure 2 .

[0067] Figure 2 These are metallographic micrographs comparing 304 stainless steel, 304 stainless steel after polarization testing, polyaniline, polyaniline-carboxymethyl chitosan, and the polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 of this invention. Figure 2 (a) Figure 2 (b) Figure 2 (c) Figure 2 (d) Figure 2 (e) Metallographic micrographs of 304 stainless steel, 304 stainless steel after polarization test, polyaniline, polyaniline-carboxymethyl chitosan and polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1, respectively.

[0068] like Figure 2 As shown in (a), the surface of the 304 stainless steel sample is smooth; Figure 2 As shown in (b), the 304 stainless steel sample exhibited severe surface corrosion after polarization testing; for example... Figure 2 As shown in (c), the surface of the polyaniline sample after polarization testing exhibits relatively deep pitting corrosion; Figure 2 As shown in (d), a small amount of pitting corrosion was observed on the surface of the polyaniline-carboxymethyl chitosan sample after polarization testing; Figure 2 As shown in (e), the surface of the polyaniline-carboxymethyl chitosan-modified boron nitride sample prepared in Example 1 was intact and without pitting corrosion after polarization testing. The results indicate that the polyaniline-carboxymethyl chitosan-modified boron nitride composite material has the best protective effect on the 304 stainless steel substrate.

[0069] The adhesion between polyaniline and the polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 was tested, and the test results are shown in [Figure 1]. Figure 3 .

[0070] Figure 3 This is a before-and-after comparison of the adhesion test results of polyaniline and the polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 of this invention.

[0071] Figure 3 (a) and Figure 3 (b) These are before-and-after comparison images of the adhesion test of polyaniline. Figure 3 (c) and Figure 3 (d) are before and after comparison of the adhesion test results of polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1.

[0072] The adhesion test references the standard GB / T9286 "Cross-cut test for paint and varnish films". This test method involves selecting different locations on the substrate, cutting a right-angled grid pattern with a tool that penetrates the coating to the substrate, fixing the center point of a specific adhesive tape, ensuring full contact between the coating and the tape with the tape direction parallel to the cut line, and smoothly peeling off the tape within 0.5s to 0.1s. Finally, the sample area is observed in a well-lit environment to grade the test sample.

[0073] According to the standard GB / T9286 "Cross-cut test for paint and varnish films", the test results of the materials are graded from 0 to 5. The specific test method is as follows: select different positions on the substrate, use a knife to cut a right-angled grid pattern that penetrates the coating to the substrate, fix the center point of a specific tape, make full contact between the coating and the tape with the tape direction parallel to the cutting line, and smoothly peel off the tape within 0.5s to 0.1s. Finally, observe the sample area in a good bright environment to grade the test sample. The higher the grade of the coating, the more coating peels off and the worse the adhesion.

[0074] GB / T9286 Adhesion Grade Standard Classification

[0075]

[0076]

[0077] like Figure 3 As shown in the comparison chart before and after the test, Figure 3 (b) The polyaniline is grade 5. Figure 3 (d) The polyaniline-carboxymethyl chitosan-modified boron nitride prepared in Example 1 was grade 1. The results show that polyaniline has poor adhesion to the substrate. After adding carboxymethyl chitosan and modified boron nitride, the adhesion of the polyaniline-carboxymethyl chitosan-modified boron nitride composite material is significantly improved, which helps to enhance the corrosion resistance of the composite material.

[0078] The role and effect of the embodiments

[0079] According to the polyaniline-carboxymethyl chitosan-modified boron nitride composite material and its preparation method provided in the above embodiments, polyaniline, containing a benzene ring structure, has a rigid structure and poor solubility, resulting in weak adhesion and poor corrosion protection when used as a protective coating for a metal substrate. However, the molecular chain of carboxymethyl chitosan can rotate freely and contains a large number of -NH2, -OH, and -COOH groups, which can act as active sites to react with polyaniline. The electrochemical combination of the two can improve the solubility of polyaniline and enhance its adhesion to the metal substrate, thereby improving the corrosion protection effect. Simultaneously, carboxymethyl chitosan itself is a good corrosion inhibitor and has viscosity, further improving the corrosion protection performance and adhesion.

[0080] Furthermore, boron nitride is a non-oxide ceramic material with advantages such as high temperature resistance and good barrier properties. It can be used as a coating to protect metal substrates, improve the mechanical properties of the coating, and enhance the adhesion of the coating to the metal substrate, thereby improving the protection of the metal. However, the covalent bonds between boron nitrides are strong, and the electrons in the structure are bound, lacking modifiable functional groups or active sites, resulting in poor dispersibility in aniline solutions. Therefore, by modifying boron nitride to increase its solubility in aniline solutions and increase the number of active sites, the polyaniline-carboxymethyl chitosan-boron nitride composite material can be better deposited on the metal surface, thus preparing a polyaniline-carboxymethyl chitosan-modified boron nitride composite material. The prepared polyaniline-carboxymethyl chitosan-modified boron nitride composite material has good corrosion resistance and significantly improved adhesion to the metal surface.

[0081] Furthermore, the method described in this embodiment for preparing polyaniline-carboxymethyl chitosan-modified boron nitride composite materials on metal surfaces via electrochemical deposition is simple to operate and has a short synthesis time.

[0082] Furthermore, when the mass ratio of modified boron nitride, carboxymethyl chitosan, and aniline is 3:10:23, the polyaniline-carboxymethyl chitosan-modified boron nitride composite material exhibits the best protective performance for the metal substrate, and the metal substrate demonstrates the strongest corrosion resistance in solution.

[0083] Furthermore, a solution pH of 4 helps improve the corrosion resistance of the polyaniline-carboxymethyl chitosan-modified boron nitride composite reinforced stainless steel substrate in solution.

[0084] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A method for preparing a polyaniline-carboxymethyl chitosan-modified boron nitride composite material, comprising the following steps: Step S1, a certain mass of hexagonal boron nitride is added to a sodium hydroxide solution with a certain concentration, grinded for a certain time, and then washed and dried to obtain a dried modified boron nitride intermediate, and the dried modified boron nitride intermediate is dispersed in isopropyl alcohol and ultrasonicated to obtain a modified boron nitride solution; Step S2, a certain mass of aniline, carboxymethyl chitosan and the modified boron nitride solution are dissolved in an inorganic acid solution with a certain concentration, and the pH value is adjusted to 1-4 to obtain a reaction solution; Step S3, the reaction solution is used as a deposition solution for electrochemical deposition, a metal is used as a to-be-plated base layer, and the metal is electrochemically deposited by a cyclic voltammetry method, so that the polyaniline-carboxymethyl chitosan-modified boron nitride composite material is obtained on the surface of the metal. 2.The method for preparing the polyaniline-carboxymethyl chitosan-modified boron nitride composite material according to claim 1, characterized in that: wherein the concentration of the sodium hydroxide solution is 0.1 mol / L-3 mol / L. 3.The method for preparing the polyaniline-carboxymethyl chitosan-modified boron nitride composite material according to claim 1, characterized in that: wherein the inorganic acid of the inorganic acid solution is any one of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid; the concentration of the inorganic acid solution is 0.1 mol / L-3 mol / L. 4.The method for preparing the polyaniline-carboxymethyl chitosan-modified boron nitride composite material according to claim 1, characterized in that, wherein, in step S3, the voltage of the cyclic voltammetry method is-0.3 V-1.5 V.

5. A polyaniline-carboxymethyl chitosan-modified boron nitride composite material, characterized by, The polyaniline-carboxymethyl chitosan-modified boron nitride composite material is prepared by the method according to any one of claims 1-4.

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