Disclosure of Invention
The invention aims to provide a functional graphene/montmorillonite/lanthanum borate composite material lubricating oil additive, a preparation method and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme: the functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive is prepared by mixing functional graphene oxide, modified lanthanum borate and montmorillonite in a mass ratio of 1 (0.25-4) to (0.5-8).
The lubricating oil additive is prepared by the following steps:
(1) preparing a dispersion liquid of graphene oxide by using graphene oxide prepared by an improved Hummers method as a raw material, adding a silane coupling agent, reacting at 25-100 ℃ for 1-6h, separating and cleaning to obtain functional graphene oxide;
(2) under the condition of heating and stirring at 60-90 ℃, sequentially adding a lanthanum nitrate aqueous solution and a silane coupling agent into a borax aqueous solution, stirring at a constant temperature for reaction for 1-5h, cooling and separating to obtain a modified lanthanum borate nano material;
(3) mixing and stirring the modified lanthanum borate, montmorillonite and functional graphene oxide dispersion liquid for 0.5-2h, heating and reacting at 100-200 ℃ for 1-5h, separating and cleaning to obtain the functional graphene/montmorillonite/lanthanum borate composite material.
Preferably, in the step (1) and the step (2), the silane coupling agent is any one of A-1100, A-1110, A-1120 and KBM-602.
Preferably, in the step (1), the mass ratio of the graphene oxide to the silane coupling agent is 1: 24-200.
Preferably, in the step (2), the mass ratio of borax to lanthanum nitrate is 1: 0.5-2; the mass ratio of the borax to the silane coupling agent is 1: 0.2-2.
Preferably, the mass ratio of the graphene oxide to the modified lanthanum borate to the montmorillonite is 1 (0.25-4) to (0.5-8).
Preferably, in the step (1) and the step (3), the graphene oxide dispersion liquid and the functional graphene oxide dispersion liquid are the same in dispersing agent, and each dispersing agent includes ethanol or water.
Preferably, in steps (1) to (3), the heating mode is reflux heating or autoclave heating reaction.
The functional graphene/montmorillonite/lanthanum borate composite material lubricating oil additive is applied, and the concentration of the additive in the lubricating oil is 0.01-0.13 wt%; the lubricating oil can be any brand of lubricating oil, such as Kunlun Scorpio F5000, SF15W-40 type lubricating oil and great wall SJ10W-40 lubricating oil, and can also be base oil such as mineral base oil or synthetic base oil.
By means of the technical scheme, the functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive prepared by the invention has the following advantages:
1) according to the invention, the graphene oxide functionally modified by the silane coupling agent is obtained by a chemical bonding composite method, and can be bonded with montmorillonite to react so as to fix montmorillonite particles;
2) the lanthanum borate is modified in the in-situ preparation process, so that the agglomeration of lanthanum borate nano particles can be reduced, and functional groups on the lanthanum borate nano particles can react and bond with functional groups on the surfaces of montmorillonite and graphene, so that a composite product of the montmorillonite, the graphene and the graphene is obtained;
3) the prepared material is an inorganic inactive material, does not contain active elements such as sulfur, phosphorus and the like, has no corrosion effect on the surface of a grinding part, and also has excellent intelligent repair capability.
Detailed Description
The present invention will be described in detail below with reference to specific examples, but the present invention is not limited thereto in any way.
With reference to fig. 1, a preparation process of the functional graphene/montmorillonite/lanthanum borate composite lubricant additive according to the present invention is given in the following example.
Example one
(1) 160g of an aqueous dispersion of 0.025 wt% graphene oxide was prepared. 6mL of the silane coupling agent (A-1100) was added, and the mixture was stirred at room temperature for 1 hour. The mixture was transferred to a flask and reacted in a water bath at 80 ℃ for 2 hours. And after separation and cleaning, adding a proper amount of deionized water to obtain the aqueous dispersion of the functional graphene oxide.
(2) Weighing 10g of lanthanum nitrate, and adding 50mL of distilled water for dissolving to prepare a lanthanum nitrate solution; weighing 12g of borax, adding 50mL of water, fully dissolving, heating to 80 ℃, keeping constant temperature, sequentially adding the lanthanum nitrate solution and 6mL of silane coupling agent (A-1100), and stirring at constant temperature for reacting for 2 h. Separating and washing to obtain the modified lanthanum borate.
(3) Adding 0.04g of modified lanthanum borate and 0.16g of montmorillonite into the aqueous dispersion of the functional graphene oxide, and stirring for 1 hour; and transferring the mixture to a reaction kettle for hydrothermal reaction at 120 ℃ for 1h, separating, cleaning and drying to obtain the functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive.
(4) Evaluation of tribological Properties
The prepared functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive is mixed with Kunlun scorpion SF15W-40 lubricating oil according to different proportions. A friction and wear test is carried out by using an MRS-10G four-ball friction and wear testing machine, and a GCr steel ball with the hardness of 770HV and the diameter of 12.7mm is used for testing. And (3) testing conditions are as follows: load 197N, speed 600rpm, time 3600 s. The TEM image of the microscopic morphology of the obtained functional graphene/montmorillonite/lanthanum borate composite lubricant additive is shown in FIG. 2, and it can be seen from the TEM image that the surface of the sheet layer with the larger wrinkled functional graphene is uniformly loaded with small montmorillonite layers, and the lanthanum borate nanoparticles are stably loaded on the surfaces of the graphene sheet layer and the montmorillonite layer. The friction coefficient and the wear scar diameter of the composite lubricant additive at different concentrations in this example are given in table 1, and the test results of the simple graphene oxide, montmorillonite and lanthanum borate at a concentration of 0.4 wt% are given for comparison, so that the composite lubricant additive prepared by comparing with a single component material has excellent lubricating performance, the friction coefficient can be reduced by about 83% and the wear scar diameter can be reduced by about 18% compared with the simple lubricant. Meanwhile, microhardness test is carried out on the grinding spot surface, and the test result is shown in table 2, so that the use of the composite material lubricating oil additive can be seen, and the hardness of the grinding spot surface is improved by 23 percent compared with that of the steel ball.
Example two
(1) 160g of an aqueous dispersion of 0.025 wt% graphene oxide was prepared. Then, 1mL of a silane coupling agent (A-1110) was added and the reaction was carried out at 25 ℃ for 5 hours. And after separation and cleaning, adding a proper amount of deionized water to obtain the aqueous dispersion of the functional graphene oxide.
(2) Weighing 10g of lanthanum nitrate, and adding 50mL of distilled water for dissolving to prepare a lanthanum nitrate solution; weighing 5g of borax, adding 50mL of water, fully dissolving, heating to 60 ℃, keeping constant temperature, sequentially adding the lanthanum nitrate solution and 3mL of silane coupling agent (A-1100), and stirring at constant temperature for reaction for 5 hours. Separating and washing to obtain the modified lanthanum borate.
(3) Adding 0.1g of modified lanthanum borate and 0.02g of montmorillonite into the aqueous dispersion of the functional graphene oxide, and stirring for 0.5 h; and transferring the mixture to a reaction kettle for hydrothermal reaction at 200 ℃ for 1h, separating, cleaning and drying to obtain the functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive.
(4) Evaluation of tribological Properties
Mixing the prepared functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive with 0.4 wt% of Kunlun scorpion SF15W-40 lubricating oil. A friction and wear test is carried out by using an MRS-10G four-ball friction and wear testing machine, and a GCr steel ball with the hardness of 770HV and the diameter of 12.7mm is used for testing. And (3) testing conditions are as follows: load 197N, speed 600rpm, time 3600 s. The test results are given in table 1.
EXAMPLE III
(1) 160g of an ethanol dispersion of graphene oxide having a concentration of 0.025 wt% was prepared. Then, 8mL of a silane coupling agent (A-1120) was added, and the reaction was refluxed at 80 ℃ for 1 hour. And separating, cleaning, and adding a proper amount of ethanol to obtain an ethanol dispersion liquid of the functional graphene oxide.
(2) Weighing 10g of lanthanum nitrate, and adding 50mL of distilled water for dissolving to prepare a lanthanum nitrate solution; weighing 20g of borax, adding 50mL of water, fully dissolving, heating to 90 ℃, keeping constant temperature, sequentially adding a lanthanum nitrate solution and 10mL of silane coupling agent (A-1120), and stirring at constant temperature for reacting for 1 h. Separating and washing to obtain the modified lanthanum borate.
(3) Adding 0.16g of modified lanthanum borate and 0.16g of montmorillonite into the ethanol dispersion liquid of the functional graphene oxide, and stirring for 2 hours; and carrying out reflux reaction for 5h at 100 ℃, separating, cleaning and drying to obtain the functional graphene/montmorillonite/lanthanum borate composite material lubricating oil additive.
(4) Evaluation of tribological Properties
Mixing the prepared functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive with 0.4 wt% of Kunlun scorpion SF15W-40 lubricating oil. A friction and wear test is carried out by using an MRS-10G four-ball friction and wear testing machine, and a GCr steel ball with the hardness of 770HV and the diameter of 12.7mm is used for testing. And (3) testing conditions are as follows: load 197N, speed 600rpm, time 3600 s. The test results are given in table 1.
Example four
(1) 160g of an ethanol dispersion of graphene oxide having a concentration of 0.025 wt% was prepared. Then, 3mL of a silane coupling agent (KBM-602) was added, and the mixture was transferred to a reaction vessel and reacted at 95 ℃ for 4 hours. And separating, cleaning, and adding a proper amount of ethanol to obtain an ethanol dispersion liquid of the functional graphene oxide.
(2) Weighing 10g of lanthanum nitrate, and adding 50mL of distilled water for dissolving to prepare a lanthanum nitrate solution; weighing 15g of borax, adding 50mL of water, fully dissolving, heating to 90 ℃, keeping constant temperature, sequentially adding a lanthanum nitrate solution and 10mL of silane coupling agent (KBM-602), and stirring at constant temperature for reacting for 1 h. Separating and washing with water to obtain the modified lanthanum borate.
(3) Adding 0.08g of modified lanthanum borate and 0.32g of montmorillonite into the ethanol dispersion liquid of the functional graphene oxide, and magnetically stirring for 2 hours; and transferring the mixture to a reaction kettle for reaction at 150 ℃ for 5 hours, separating, cleaning and drying to obtain the functional graphene/montmorillonite/lanthanum borate composite material lubricating oil additive.
(4) Evaluation of tribological Properties
Mixing the prepared functional graphene/montmorillonite/lanthanum borate composite lubricating oil additive with 0.4 wt% of Kunlun scorpion SF15W-40 lubricating oil. A friction and wear test is carried out by using an MRS-10G four-ball friction and wear testing machine, and a GCr steel ball with the hardness of 770HV and the diameter of 12.7mm is used for testing. And (3) testing conditions are as follows: load 197N, speed 600rpm, time 3600 s. The test results are given in table 1.
TABLE 1 Friction coefficient and wear scar diameter of lubricating oil additives of different materials
TABLE 2 micro-hardness test results for the abraded surfaces