A PDA rapid deposition modified silicon carbide-polyurea composite material and a preparation method thereof

Abstract

The application discloses a PDA rapid deposition modified silicon carbide-polyurea composite material in the technical field of polyurea composite materials and a preparation method thereof, and aims to solve the problem of poor interface bonding between silicon carbide and polyurea in the silicon carbide-polyurea composite material in the prior art, and comprises a surface modified silicon carbide base material, the surface of the silicon carbide base material is coated with polyurea, and components of the polyurea include terminal amino polyether and diphenyl methane diisocyanate; the soft segment molecular weight of the terminal amino polyether is 650. The application is favorable for improving the interface bonding force between silicon carbide and polyurea and the integrity of the composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to a PDA rapid deposition modified silicon carbide-polyurea composite material and a preparation method thereof, and belongs to the technical field of polyurea composite materials. BACKGROUND

[0002] Silicon carbide (SiC) is a carbide formed by the combination of Si and C through covalent bonds. It has very high hardness, second only to diamond and boron carbide, and its crystal structure is similar to that of diamond, which is tightly packed by Si-C tetrahedrons. Due to its high strength and light weight, silicon carbide (SiC) has always been considered as one of the most ideal materials for making bulletproof equipment, but the low toughness of SiC material makes it easy to produce large-area fracture under bullet impact, and its weak resistance to multiple hits is a major shortcoming.

[0003] Polyurea (PU) is an elastomer material generated by the reaction of isocyanate (Isocyanate) component and amino compound component. Its chemical structure is similar to that of polyesters, but it has higher hardness, strength, wear resistance, corrosion resistance, chemical resistance, weather resistance and impact resistance. Polyurea is one of the materials applied in the field of lightweight protection, mainly used to cope with shock waves and fragment penetration caused by warhead explosion effects and other damage threats. Polyurea material is usually formed by spraying technology and widely used in protective applications.

[0004] SiC ceramic sheets and polyurea materials are combined to form a new type of bulletproof armor structure. The high strength and high hardness of the ceramic itself and the large deformation energy absorption of the polyurea between the ceramic sheet layers can realize the synergistic toughening effect of the bulletproof performance. Although polyurea coating on SiC can improve the overall performance of the material, the interface bonding between silicon carbide and polyurea is relatively poor, which restricts the overall performance of the composite after the combination of SiC and polyurea. At present, there is no better way to combine SiC and polyurea to form a composite material with better performance. Therefore, it is of great significance to study the combination of sintered silicon carbide and polyurea. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a PDA rapid deposition modified silicon carbide-polyurea composite material and a preparation method thereof, which can improve the interface bonding force between silicon carbide and polyurea and the integrity of the composite material.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In one aspect, the present application provides a PDA rapid deposition modified silicon carbide-polyurea composite material, comprising a surface modified silicon carbide substrate, the surface of the silicon carbide substrate being coated with polyurea, the components of the polyurea comprising an amino-terminated polyether and diphenylmethane diisocyanate, the soft segment molecular weight of the amino-terminated polyether being 650.

[0008] Optionally, the molar ratio R(NCO / NH) of the amino-terminated polyether and the diphenylmethane diisocyanate is 1-1.1.

[0009] In another aspect, the present application provides a preparation method of a PDA rapid deposition modified silicon carbide-polyurea composite material, the method being used for preparing the PDA rapid deposition modified silicon carbide-polyurea composite material described above, and comprising the following steps:

[0010] a. surface treatment of a silicon carbide substrate to obtain a surface treated silicon carbide substrate;

[0011] b. adding H2O2 and CuSO4 to a tris-hydroxymethyl aminomethane buffer solution containing dopamine hydrochloride, and dissolving and stirring to obtain a polydopamine deposition solution;

[0012] c. immersing the surface treated silicon carbide substrate into the polydopamine deposition solution, and performing a room temperature shock reaction, and then washing and drying to obtain a PDA rapid deposition modified silicon carbide substrate;

[0013] d. preparing polyurea and coating the polyurea on the surface of the PDA rapid deposition modified silicon carbide substrate to obtain a PDA rapid deposition modified silicon carbide-polyurea composite material.

[0014] Optionally, the surface treatment of the silicon carbide in step a is cleaning with anhydrous ethanol.

[0015] Optionally, the concentration of dopamine hydrochloride in step b is 1-3 g / L, the concentration of the tris-hydroxymethyl aminomethane buffer solution is 40-60 mM, the pH is 7.5-8.5, the concentration of H2O2 is 18-20 mM, and the concentration of CuSO4 is 4-6 mM.

[0016] Optionally, the concentration of dopamine hydrochloride in step b is 2 g / L, the concentration of the tris-hydroxymethyl aminomethane buffer solution is 50 mM, the pH is 8, the concentration of H2O2 is 19.6 mM, and the concentration of CuSO4 is 5 mM.

[0017] Optionally, the washing and drying in step c comprises washing the reacted silicon carbide substrate with deionized water more than three times, and drying at 50-70°C for more than 12 h.

[0018] Optionally, the preparation method of the polyurea in step d comprises stirring and mixing the amino-terminated polyether with a soft segment molecular weight of 650 and the diphenyl methane diisocyanate uniformly.

[0019] Optionally, the stirring rate is 1000-3000 r / min, and the stirring time is 20-40 s.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The present application carries out surface modification treatment on silicon carbide by PDA rapid deposition method, composites the silicon carbide after surface modification with polyurea, and limits the polyurea to be prepared by mixing the amino-terminated polyether with a soft segment molecular weight of 650 and the isocyanate according to a molar ratio R(NCO / NH) = 1.05, to obtain a new type of composite material. The composite material fully gives the advantages of both, the silicon carbide therein can provide high hardness, high strength and high temperature stability, etc., the polyurea increases the toughness and impact resistance of the composite material, and the PDA greatly improves the dry-state adhesion and wet-state adhesion between the silicon carbide and the polyurea after surface modification of the silicon carbide, effectively enhances the bonding of the composite interface of the silicon carbide and the polyurea, solves the problem of weak bonding of the composite interface of the silicon carbide and the polyurea, makes the overall composite material have high structural stability, strong tear strength, hardness and wear resistance, and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a schematic diagram of the modification reaction process of silicon carbide in the preparation method of the PDA rapid deposition modified silicon carbide-polyurea composite material in one embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of the test results of the dry-state adhesion of the PDA rapid deposition modified silicon carbide-polyurea composite material in one embodiment of the present application.

[0024] Figure 3 It is a schematic diagram of the test results of the wet-state adhesion of the PDA rapid deposition modified silicon carbide-polyurea composite material in one embodiment of the present application. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0026] Example 1:

[0027] The embodiment of the present application provides a PDA rapid deposition modified silicon carbide-polyurea composite material, which comprises a surface modified silicon carbide substrate, and the surface of the silicon carbide substrate is uniformly coated with polyurea; the surface modified silicon carbide substrate is obtained by modification through a PDA rapid deposition method.

[0028] The preparation method of the PDA rapid deposition modified silicon carbide-polyurea composite material comprises the following steps:

[0029] a. The silicon carbide substrate is subjected to surface cleaning by using anhydrous ethanol to obtain a surface treated silicon carbide substrate.

[0030] b. H2O2 and CuSO4 are added to 100ml of a tris-hydroxymethyl aminomethane buffer solution containing dopamine hydrochloride, and after being fully dissolved and stirred, a rapid technical polydopamine deposition solution is obtained; wherein the concentration of dopamine hydrochloride is 2g / L, the pH of the tris-hydroxymethyl aminomethane buffer solution is 8, the concentration of the tris-hydroxymethyl aminomethane buffer solution is 50mM, the concentration of H2O2 is 19.6mM, and the concentration of CuSO4 is 5mM.

[0031] c. The silicon carbide substrate with the surface wiped by anhydrous ethanol is immersed into the polydopamine deposition solution, and oscillation reaction is carried out at room temperature for 1h; after the reaction is completed, the sample is washed with deionized water for more than three times, and then is placed in a 60℃ drying box for drying for more than 12h to obtain a PDA rapid deposition method modified silicon carbide substrate, and the modification route is as shown in Figure 1 .

[0032] d. The end-amino polyether with a soft segment molecular weight of 650 is uniformly mixed with diphenyl methane diisocyanate by stirring, the stirring mode is a self-rotation and revolution stirrer, the rotation speed of the self-rotation and revolution is set to 2000r / min, and the stirring time is 30s; polyurea is prepared and is coated on the surface of the PDA rapid deposition modified silicon carbide substrate to obtain a PDA rapid deposition modified silicon carbide-polyurea composite material.

[0033] Comparative Example 1

[0034] The difference between the embodiment and the embodiment 1 is that the surface of the silicon carbide is not modified.

[0035] Comparative Example 2

[0036] The difference between this embodiment and embodiment 1 is only that the surface of the silicon carbide substrate is modified by PDA traditional modification. That is, 100 ml of a tris-hydroxymethyl aminomethane buffer solution containing dopamine hydrochloride and ascorbic acid is configured, wherein the concentration of dopamine hydrochloride is 2 g / L, the pH of the tris-hydroxymethyl aminomethane buffer solution is 8, and the concentration of the tris-hydroxymethyl aminomethane buffer solution is 50 mM; the silicon carbide substrate with the surface wiped by anhydrous ethanol is immersed in the tris-hydroxymethyl aminomethane buffer solution, and oscillation reaction is carried out at room temperature for 24 h. After the reaction is completed, the sample is washed with deionized water for more than three times, and then is placed in a drying oven at 60°C for drying for more than 12 h to obtain the PDA traditionally modified silicon carbide substrate.

[0037] Comparative example 3:

[0038] The difference between this embodiment and embodiment 1 is only that the surface of the silicon carbide substrate is modified by tannic acid. That is, the silicon carbide substrate with the surface wiped by anhydrous ethanol is placed in 100 ml of a tannic acid solution with a concentration of 2 g / L, and constant temperature oscillation reaction is carried out at room temperature for 24 h. Then the sample is washed with deionized water for more than three times, and then the sample is placed in an oven at 60°C for drying for more than 12 h to obtain the tannic acid modified silicon carbide substrate.

[0039] Comparative example 4:

[0040] The difference between this embodiment and embodiment 1 is only that the polyurea is prepared by mixing two kinds of soft segment end amino polyether with molecular weights of 1000 and 650 with liquefied MDI according to a molar ratio R(NCO / NH) = 1.05, wherein the mass ratio of the soft segment end amino polyether with a molecular weight of 1000 to the soft segment end amino polyether with a molecular weight of 650 is 7:3.

[0041] Comparative example 5:

[0042] The difference between this embodiment and embodiment 1 is only that the urea is prepared by mixing two kinds of soft segment end amino polyether with molecular weights of 1000 and 650 with liquefied MDI according to a molar ratio R(NCO / NH) = 1.05, wherein the mass ratio of the soft segment end amino polyether with a molecular weight of 1000 to the soft segment end amino polyether with a molecular weight of 650 is 3:7.

[0043] Performance tests are carried out on embodiment 1 and comparative examples 1-5.

[0044] (1) Contact angle and surface energy test: The contact angle of the silicon carbide surface is tested according to the method of GB / T 30693-2014.

[0045] Testing revealed that the contact angle of Comparative Example 1 was 43.3°, indicating that the silicon carbide surface had high polarity and could not be well wetted by the polyurea prepolymer. The water contact angle of Example 1 was 83.8°, while the water contact angle of Comparative Example 2 was 68.5° and the water contact angle of Comparative Example 3 was 57.5°, all lower than that of Example 1.

[0046] It is known that the PDA rapid deposition modified silicon carbide-polyurea composite material prepared by the present invention has a mixture of polyurea prepolymer and curing agent that is easier to spread on the substrate, which is beneficial to the interaction with the modified silicon carbide surface, thereby improving the dry and wet adhesion between silicon carbide and polyurea.

[0047] (2) Adhesion test:

[0048] The adhesion of silicon carbide and polyurea characterizes the bond strength between these two materials and can also be used to assess the reliability of their interface and determine whether the bond between the materials is strong. Silicon carbide and polyurea are two very different materials, and their bonding faces both chemical interface interactions and stress distribution at the mechanical interface.

[0049] (2-1) Dry adhesion test: The spindle was bonded to the polyurea on the surface of silicon carbide using AB adhesive. After being placed at room temperature for 48 hours, the dry adhesion of the modified silicon carbide and polyurea composite structure was measured by pull-out method.

[0050] The experimental results of the dry adhesion test of Example 1 and Comparative Examples 1-5 are as follows: Figure 2 As shown.

[0051] from Figure 2 As can be seen, the dry adhesion between unmodified silicon carbide and polyurea in Comparative Example 1 was 10.8 MPa, while the dry adhesion between silicon carbide and polyurea in Example 1 increased to 12.5 MPa; and the dry adhesion of Comparative Examples 2 to 5 was lower than that of Example 1, and even lower than that of Comparative Example 1.

[0052] (2-2) The test method for wet adhesion is as follows:

[0053] Examples 1 and Comparative Examples 1-3 were all immersed in artificial seawater for 1 day, then dried for 24 hours at a temperature of 25°C and a humidity of 50%, and air-dried naturally. The spindles were then bonded to the polyurea on the surface of silicon carbide using AB adhesive. After being placed at room temperature for 48 hours, their wet adhesion was measured using the pull-off method.

[0054] The test results of wet adhesion are as follows Figure 3 As shown.

[0055] from Figure 3As can be seen, the wet-state adhesion between the unmodified silicon carbide and the polyurea in Comparative Example 1 is 9.5 MPa after immersion in artificial seawater, and the wet-state adhesion of Comparative Examples 1-3 is greatly reduced. The wet-state adhesion of Example 1 is greatly improved, reaching 12.5 MPa.

[0056] (3) Solution erosion test:

[0057] Example 1 and Comparative Examples 1-3 were immersed in a toluene / ammonia solution for 24 h, and the erosion of the toluene solvent on the bonding interface of the sample was observed. The results show that, in addition to the dispersion effect, there is also a small amount of hydrogen bonding between the surface of the unmodified silicon carbide in Comparative Example 1 and the polyurea, and the hydrogen bonding between the surface of the silicon carbide in Example 1 and the polyurea is stronger.

[0058] (4) Mechanical property test of polyurea:

[0059] A universal testing machine was used to test the tear strength of the polyurea in Example 1 and Comparative Examples 4-5, and a vernier caliper was used to measure the thickness of the sample before testing, with 3 measurements taken for each sample and the average value taken. The test results are shown in Table 1.

[0060] A LX-A type Shore hardness tester was used to test the surface hardness of the polyurea in Example 1 and Comparative Examples 4-5, and the test results are shown in Table 1.

[0061] A ZJ-5135 type coating wear tester was used to test the wear resistance of the polyurea in Example 1 and Comparative Examples 4-5, and the test was performed at a rotation speed of 60 r / min and a number of 500 r. The mass of the sample before and after wear was accurately measured by an electronic analytical balance. After the test, the sandpaper was ground for 250 cycles before the next test. The test results are shown in Table 1.

[0062] Table 1 Mechanical properties of polyurea

[0063] Sample Tear strength / MPa Hardness Mass change Example 1 126.3 100.3 0.8 Comparative Example 4 89.2 97.2 1.3 Comparative Example 5 119.2 96.1 0.9

[0064] As can be seen, the tear strength, hardness and wear resistance of Example 1 are all strong.

[0065] In summary, the PDA rapid deposition modified silicon carbide-polyurea composite material prepared in the example fully utilizes the advantages of both, the silicon carbide can provide high hardness, high strength and high temperature stability, the polyurea increases the toughness and impact resistance of the composite material, and the PDA greatly improves the dry-state adhesion and wet-state adhesion between the silicon carbide and the polyurea after modification of the silicon carbide surface, effectively enhancing the bonding of the silicon carbide and the polyurea composite interface, solving the problem of weak bonding of the silicon carbide and the polyurea composite interface, making the overall composite material structure stable, with strong tear strength, hardness and wear resistance, and long service life.

[0066] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application, and these improvements and modifications should also be considered as falling within the protection scope of the present application.

Claims

1. A PDA rapid deposition modified silicon carbide-polyurea composite material, characterized in that, The invention includes a surface-modified silicon carbide substrate, the surface of which is coated with polyurea, the polyurea comprising an amino-terminated polyether and diphenylmethane diisocyanate, wherein the soft segment molecular weight of the amino-terminated polyether is 650. The method for preparing the surface-modified silicon carbide substrate includes: a. Surface treatment is performed on the silicon carbide substrate to obtain the surface-treated silicon carbide substrate; b. Add H2O2 and CuSO4 to the tris(hydroxymethyl)aminomethane buffer containing dopamine hydrochloride, dissolve and stir to obtain polydopamine deposition solution; c. Immerse the surface-treated silicon carbide substrate in a polydopamine deposition solution, shake and react at room temperature, clean and dry to obtain a surface-modified silicon carbide substrate.

2. The PDA rapid deposition modified silicon carbide-polyurea composite material according to claim 1, characterized in that, The molar ratio R(NCO / NH) of the terminal amino polyether and diphenylmethane diisocyanate is 1~1.

1.

3. A method for preparing PDA-modified silicon carbide-polyurea composite material as described in claim 1 or 2, characterized in that, Includes the following steps: Polyurea was prepared and coated onto the surface of the surface-modified silicon carbide substrate to obtain a PDA-modified silicon carbide-polyurea composite material.

4. The method for preparing PDA-modified silicon carbide-polyurea composite material according to claim 3, characterized in that, In step a, the surface treatment of silicon carbide is cleaning with anhydrous ethanol.

5. The method for preparing PDA-modified silicon carbide-polyurea composite material according to claim 3, characterized in that, In step b, the concentration range of dopamine hydrochloride is 1~3 g / L, the concentration range of tris(hydroxymethyl)aminomethane buffer is 40~60 mM, its pH is 7.5~8.5, the concentration range of H2O2 is 18~20 mM, and the concentration range of CuSO4 is 4~6 mM.

6. The method for preparing PDA-modified silicon carbide-polyurea composite material according to claim 5, characterized in that, In step b, the concentration of dopamine hydrochloride is 2 g / L, the concentration of tris(hydroxymethyl)aminomethane buffer is 50 mM with pH=8, the concentration of H2O2 is 19.6 mM, and the concentration of CuSO4 is 5 mM.

7. The method for preparing PDA-modified silicon carbide-polyurea composite material according to claim 3, characterized in that, Step c, cleaning and drying, includes cleaning the reacted silicon carbide substrate three or more times with deionized water and drying it at 50~70℃ for more than 12 hours.

8. The method for preparing PDA-modified silicon carbide-polyurea composite material according to claim 3, characterized in that, The preparation method of polyurea in step d includes stirring and mixing a terminal amino polyether with a soft segment molecular weight of 650 with diphenylmethane diisocyanate until homogeneous.

9. The method for preparing PDA-modified silicon carbide-polyurea composite material according to claim 8, characterized in that, The stirring rate is 1000~3000 r / min, and the stirring time is 20~40 s.

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