Modified MoS2 / graphene oxide composite material and preparation method thereof

Abstract

The invention discloses a modified MoS2 / graphene oxide composite material and a preparation method thereof. The preparation method comprises the following steps: modifying commercial MoS2 by using a silane coupling agent to enable the commercial MoS2 to be positively charged, and then self-assembling with negatively charged graphene oxide to obtain the modified MoS2 / graphene oxide composite material. When the composite material is added into an epoxy resin solid coating as an additive, the friction coefficient can be effectively reduced, and the corrosion resistance can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of corrosion and protection technology, and particularly relates to a modified MoS 2 / graphene oxide composite material and preparation method thereof. Background Art

[0002] Two-dimensional nanomaterials, such as graphene and molybdenum disulfide, have high research and application value in the fields of anti-wear, friction reduction, self-lubrication and metal corrosion protection due to their unique structural characteristics. The filler of the two-dimensional nanostructure gives the anti-corrosion coating a maze effect, increases physical shielding, and enhances the anti-permeability of the anti-corrosion coating. The two-dimensional structure of graphene gives it inherent inter-layer slip ability and extraordinary electron transport properties and thermal conductivity. When used alone, the friction reduction effect is obvious, but the improvement of wear spot hardness is limited. Compared with graphene, although the conductivity of graphene oxide is reduced, it retains the large specific surface area of ​​the two-dimensional material, and its thermal conductivity and mechanical properties are still very outstanding compared with other two-dimensional inorganic nanomaterials; at the same time, due to the presence of a large number of oxygen-containing functional groups, it can be chemically bonded and assembled with other components.

[0003] Two-dimensional layered structure of molybdenum disulfide (MoS 2 ) contains covalent bonds and metallic bonds between Mo and S, and the layers are only connected to each other by van der Waals forces. Its unique high-level intra-bonding force and low inter-layer bonding force give MoS2 excellent self-lubricating properties. However, MoS2 is easily oxidized at high temperatures. During high-speed and high-load friction, it is easily converted into oxides, resulting in a weakened lubrication effect. Therefore, researchers adopted the method of preparing MoS2 composite materials to improve the high-temperature instability of single MoS2 [Qin Jian, Liu Tianxia, ​​Wang Jian, Lu Xing. Preparation and tribological properties of oleic acid-modified graphene / MoS2 composite lubricating additives, Chemical Progress, 2022, 9: 4973-4985; A MoS2 self-lubricating composite coating and its preparation method and use, patent application number: CN201810789192.7]. However, the in-situ synthesis technology routes of many MoS2 composite materials are complicated, and the dispersibility of two-dimensional nanomaterials in solid coatings such as epoxy resins is poor, which affects their practical application. Summary of the invention

[0004] In view of the above problems, the present invention aims to provide a modified MoS 2 / graphene oxide composite material and preparation method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a modified MoS 2 A method for preparing a graphene oxide composite material comprises the following steps:

[0007] (1) MoS 2 Ultrasonic exfoliation was performed in solvent to obtain MoS 2 Dispersion liquid;

[0008] (2) After pre-hydrolysis, the silane coupling agent is directly added to the exfoliated MoS 2 After stirring evenly, the temperature is raised to a certain level and kept at this temperature for a period of time to make MoS 2 Positively charged;

[0009] (3) Adding the graphene oxide dispersion to the mixed solution of step (2), fully mixing and stirring for self-assembly, and then separating, washing and drying to obtain modified MoS 2 / graphene oxide composites.

[0010] Furthermore, in step (1), the solvent is water, ethanol or a mixed solution.

[0011] Furthermore, in step (1), ultrasonic peeling refers to using high power 2kW and low power 300W ultrasound alternately for 15 minutes each, for 3-6 consecutive cycles.

[0012] Furthermore, in step (2), the silane coupling agent is selected from any one of KH-550, KH792, and HD520.

[0013] Furthermore, in step (2), the silane coupling agent is pre-hydrolyzed by placing the silane coupling agent in water and stirring for at least 30 minutes. The purpose of pre-hydrolysis is to make the silane coupling agent better dissolved in water, so that MoS 2 The positive charges on the surface are more evenly distributed, thus promoting the positively charged MoS 2 Further reaction with graphene oxide.

[0014] Furthermore, in step (2), the amount of silane coupling agent added is 1-5 mL of silane coupling agent per gram of MoS 2 .

[0015] Furthermore, in step (2), the temperature is raised to 60-90° C. and kept warm for 2-5 hours.

[0016] Furthermore, MoS 2 The mass ratio to graphene oxide is 1:(1~5).

[0017] Furthermore, in step (3), the stirring speed is 400 to 800 r / min, and the sufficient stirring time is 9 to 14 h.

[0018] In a second aspect, the present invention provides a modified MoS prepared by the method of the first aspect.2 / graphene oxide composites.

[0019] In a third aspect, the present invention also provides a modified MoS prepared by the method of the first aspect. 2 Application of graphene oxide composites as coating additives.

[0020] Furthermore, the coating at least includes epoxy resin, curing agent and additives, and the solid content of the additives in the coating is 0.1 to 3 wt%.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] The present invention uses an electrostatic self-assembly method to transform positively charged commercial MoS 2 Bonding and self-assembly with negatively charged graphene oxide to obtain modified MoS supported by a two-dimensional carbon layer. 2 Compared with the graphene and MoS synthesized by high temperature in situ growth, 2 The synthesis of the composite material is safe, reliable and easy to control. 2 The strong interfacial interaction between nanosheets and graphene oxide enhances its anti-wear, friction-reducing and corrosion-resistant properties in epoxy coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The modified MoS prepared in Example 1 2 TEM image of the graphene oxide / graphene oxide composite material. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below through specific implementation examples, but the implementation examples do not limit the present invention in any form.

[0025] The present invention prepares a modified MoS by a new electrostatic self-assembly method 2 / graphene oxide composite materials, and the prepared modified MoS 2 / graphene oxide composites were added to epoxy resin coatings, and their anti-wear and friction-reducing lubrication properties and metal anti-corrosion properties were evaluated.

[0026] Example 1

[0027] (1) Take 0.2 g of commercially available MoS 2 Prepare 80 mL of aqueous dispersion, and use 2 kW high power and 300 W low power alternating ultrasound for 15 min, and cycle for 3 cycles to obtain the exfoliated MoS 2 Dispersion.

[0028] (2) Take 1 ml of silane coupling agent (KH792) and add 80 mL of water for pre-hydrolysis and stirring for 30 min, then add it to the exfoliated MoS 2 The dispersion was reacted in a water bath at 90 °C for 3 h to obtain modified MoS 2 Dispersion.

[0029] (3) Disperse 0.2 g of commercially available graphene oxide into 80 mL of water to prepare a graphene oxide dispersion. 2 The dispersion was added to the graphene oxide dispersion and stirred for 9 h at a speed of 400 r / min. After the reaction was completed, the mixture was separated, washed with water, and dried to obtain modified MoS 2 Composite materials, such as TEM Figure 1 shown.

[0030] (4) The prepared modified MoS 2 / graphene oxide composite material as a coating additive, specifically: take 0.1g modified MoS 2 Composite material, 2mL of curing agent methyl hexahydrophthalic anhydride was added to 2g of epoxy resin to prepare epoxy resin coating, which was coated on a 2cm*2cm stainless steel substrate. The coating thickness was controlled at about 100μm. The prepared epoxy resin coating was named A1.

[0031] (5) Evaluation of tribological properties

[0032] The UMT-3 universal friction and wear tester was used to conduct a ball-on-disk friction and wear test on the solid coating to test the tribological properties of the composite coating. The test conditions were as follows: speed of 382 r / min, load of 30 N, friction time of 1800 s, adjustment amplitude of 1 N, and the dual ball was a GCr15 ball with a diameter of 5 mm. The results of the hardness, friction coefficient and wear volume of the coating are shown in Table 1.

[0033] (6) Anticorrosion properties

[0034] After sealing the bottom, sides and back of the coating, leave 1cm for testing. 2 The coating A1 in the area was immersed in a 3.5% NaCl salt solution for electrochemical testing. The anticorrosion performance of the solid coating was studied using the Jiangsu Donghua electrochemical workstation. The electrochemical test conditions were: open circuit potential 1000s; impedance test frequency 10 -2 Hz-10 5 The low frequency impedance of the coating on the 25th day is shown in Table 2.

[0035] Example 2

[0036] The other processes are the same as in Example 1, except that: in step (2), 5 ml of silane coupling agent KH550 is added to 80 mL of water for pre-hydrolysis and stirred for 30 min, and MoS is added. 2 The dispersion was reacted in a water bath at 60 °C for 5 h to obtain modified MoS 2 Dispersion.

[0037] The modified MoS prepared in this example 2 The epoxy resin coating prepared from the graphene oxide / graphene oxide composite material was named A2.

[0038] After friction and wear test, the test results are shown in Table 1.

[0039] After electrochemical testing, the low-frequency impedance of A2 on the 25th day is shown in Table 2.

[0040] Example 3

[0041] The other processes are the same as those in Example 1, except that: in step (2), 3 ml of silane coupling agent HD520 is added to 80 ml of water for pre-hydrolysis and stirred for 30 min, and MoS is added. 2 The dispersion was reacted in a water bath at 70 °C for 2 h to obtain modified MoS 2 Dispersion.

[0042] The modified MoS prepared in this example 2 The epoxy resin coating prepared from the graphene oxide / graphene oxide composite material was named A3.

[0043] After friction and wear test, the test results are shown in Table 1.

[0044] After electrochemical testing, the low-frequency impedance of A3 on the 25th day is shown in Table 2.

[0045] Example 4

[0046] The other processes are the same as in Example 1, except that in step (3), the amount of commercially available graphene oxide is changed to 0.3 g.

[0047] The modified MoS prepared in this example 2 The epoxy resin coating prepared from the nanostructured carbon fiber / graphene oxide composite material was named A4.

[0048] After friction and wear test, the test results are shown in Table 1.

[0049] After electrochemical testing, the low-frequency impedance of A4 on the 25th day is shown in Table 2.

[0050] Example 5

[0051] The other processes are the same as those of Example 1, except that in step (3), the amount of commercially available graphene oxide is changed to 0.4 g.

[0052] The modified MoS prepared in this example 2 The epoxy resin coating prepared from the graphene oxide / graphene oxide composite material was named A5.

[0053] After friction and wear test, the test results are shown in Table 1.

[0054] After electrochemical testing, the low-frequency impedance of A5 on the 25th day is shown in Table 2.

[0055] Example 6

[0056] The other processes are the same as those in Example 1, except that in step (3), the amount of commercially available graphene oxide is changed to 0.5 g.

[0057] The modified MoS prepared in this example 2 The epoxy resin coating prepared from the graphene oxide / graphene oxide composite material was named A6.

[0058] After friction and wear test, the test results are shown in Table 1.

[0059] After electrochemical testing, the low-frequency impedance of A6 on the 25th day is shown in Table 2.

[0060] Comparative Example 1

[0061] As a comparison, an epoxy resin coating without any additives was prepared, that is, the process of preparing the coating was the same as step (4) of Example 1, except that the modified MoS 2 / graphene oxide composite material was changed to 0g, and the obtained epoxy resin coating was named B1. After friction and wear experiments and electrochemical tests, the results are shown in Table 1 and Table 2, respectively.

[0062] Comparative Example 2

[0063] As a comparison, steps (1) and (2) in Example 2 were repeated to modify the modified MoS 2 The modified MoS was obtained after freeze-drying the dispersion. 2 .

[0064] Modified MoS with 0.1 g 2 An epoxy resin coating was prepared as an additive in the same manner as step (4) of Example 2. The obtained epoxy resin coating was named B2. The friction and wear test and electrochemical test results were shown in Tables 1 and 2, respectively.

[0065] Comparative Example 3

[0066] For comparison, 0.1 g of commercially available graphene oxide was used as an additive to prepare an epoxy resin coating. The process was the same as step (4) of Example 1. The obtained epoxy resin coating was named B3. After friction and wear tests and electrochemical tests, the results are shown in Tables 1 and 2, respectively.

[0067] Comparative Example 4

[0068] In comparison, MoS 2 The epoxy resin coating was prepared by using the composite material of graphene oxide as an additive. The process was the same as in Example 1, except that step (2) was not performed, that is, the exfoliated MoS prepared in step (1) was removed. 2 The dispersion and graphene oxide are mixed and stirred to obtain MoS 2 / graphene oxide composites.

[0069] With 0.1g MoS 2 The epoxy resin coating was prepared by using the graphene oxide composite material as an additive, and the process was the same as step (4) of Example 1. The obtained epoxy resin coating was named B4. The friction and wear test and electrochemical test results were shown in Table 1 and Table 2, respectively.

[0070] Table 1 Hardness, friction coefficient, and wear data of the coatings of Examples 1 to 6 and Comparative Examples 1 to 4

[0071]

[0072] Table 2 Low frequency impedance data of coatings of Examples 1 to 6 and Comparative Examples 1 to 4 on the 25th day

[0073]

[0074]

[0075] Compared with the four comparative samples B1-B4 (containing no composite material, containing only a single component material, and containing a physically mixed composite material), the composite material containing the modified MoS prepared by the present invention 2 The epoxy resin coating of the MoS / graphene oxide composite material has significantly enhanced anti-wear and friction-reducing lubrication properties, as well as more superior physical shielding and anti-corrosion properties, which is due to the modified MoS prepared by the technology of the present invention. 2 The strong interaction and bonding forces between the two components of the graphene / oxide composite material produce a synergistic effect.

Claims

1. A method for preparing a modified MoS2 / graphene oxide composite material, characterized in that: The following steps are involved: (1) ultrasonically exfoliating MoS2 in a solvent to obtain a MoS2 dispersion; (2) After pre-hydrolysis, the silane coupling agent is directly added to the exfoliated MoS2 dispersion, stirred evenly, and then heated to a certain temperature and kept warm for a period of time to make the MoS2 positively charged; (3) adding the graphene oxide dispersion to the mixed solution of step (2), mixing and stirring thoroughly for self-assembly and composite, and then separating, washing and drying to obtain a modified MoS2 / graphene oxide composite material.

2. The method according to claim 1, characterized in that In step (1), the solvent is water, ethanol or a mixed solution.

3. The method according to claim 1, characterized in that In step (1), ultrasonic peeling refers to using high power 2kW and low power 300W ultrasound alternately for 15 minutes each, for 3-6 consecutive cycles.

4. The method according to claim 1, characterized in that In step (2), the silane coupling agent is selected from any one of KH-550, KH792, and HD520.

5. The method according to claim 1, characterized in that In step (2), the amount of silane coupling agent added is 1-5 mL of silane coupling agent per gram of MoS2.

6. The method according to claim 1, characterized in that In step (2), the temperature is raised to 60-90° C. and kept warm for 2-5 hours.

7. The method according to claim 1, characterized in that The mass ratio of MoS2 to graphene oxide is 1:(1~5).

8. A modified MoS2 / graphene oxide composite material prepared by the method as described in any one of claims 1 to 7.

9. Use of a modified MoS2 / graphene oxide composite material prepared by the method as described in any one of claims 1 to 7 as a coating additive.

10. The use according to claim 9, characterized in that The solid content of the additive in the coating is 0.1 to 3 wt%.

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