Preparation method of LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive

Abstract

The invention belongs to the technical field of lubricating oil additives, and particularly relates to a preparation method of an LDH derived bimetallic sulfide composite boron nitride lubricating oil additive. Nickel nitrate and magnesium chloride are used as metal sources, metal elements are loaded on the surface of boron nitride through an aging reaction to form an LDH precursor, sublimed sulfur is used as a sulfur source for a vulcanization reaction, the LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive is prepared, and the friction performance of the LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive is effectively improved when the LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive is applied to lubricating oil.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricating oil additives, and particularly relates to a preparation method of an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive. Background Art

[0002] Lubrication is ubiquitous in everyday life and industrial production. When two objects move relative to each other, friction hinders that motion and wears the surfaces, leading to a range of problems such as mechanical component failure, system malfunction, and economic and energy losses. Lubricants with high lubrication efficiency, ease of use, and low cost not only reduce friction and wear and energy consumption but also remove rust, seal, and remove impurities, thereby better protecting mechanical equipment. Lubricants effectively extend the service life of mechanical equipment and can be used under varying operating conditions of temperature, load, and speed. Lubricants are primarily composed of base oil and additives. The base oil is the main component of the lubricant, while the additives are the core components. Based on their effectiveness, they are categorized as extreme pressure, anti-wear, antioxidant, anti-corrosion, and detergent additives. Currently, nanomaterials with large specific surface areas and high binding energy exhibit excellent physical and chemical properties. The addition of these nanomaterials to lubricants significantly improves the tribological performance of lubricants. Layered double hydroxides (LDHs) are an important class of layered inorganic crystalline materials with unique electrical properties, layered structures, and ion exchange capacity. They have become a highly sought-after new nanomaterial and are being researched for their application in lubricant additives.

[0003] A Chinese patent (publication number CN117210263A) discloses an ionic liquid functionalized boron nitride lubricant additive and its preparation method and application. The additive prepared by the invention is modified by ionic liquid to modify hydroxy boron nitride to obtain an ionic liquid functionalized hydroxy boron nitride additive, which is then dispersed into lubricating oil and used as a lubricant additive. The use of phosphorus-containing ionic liquids can better improve the material's dispersibility in oil and lubrication performance. The raw materials used are widely available, the process costs involved are low, and the reaction conditions are mild. However, in the prior art, the sulfidation of layered double hydroxides (LDHs) and their combination with boron nitride as lubricant additives to improve the friction performance of lubricants have not been studied in detail.

[0004] Therefore, there is an urgent need for an LDH-derived bimetallic sulfide composite boron nitride lubricant additive, which can effectively improve the friction performance of lubricating oil during application by sulfiding the layered double hydroxide and synergizing it with boron nitride. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for preparing an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive. Nickel nitrate and magnesium chloride are used as metal sources. The metal elements are loaded on the surface of boron nitride through an aging reaction to form an LDH precursor. Sublimated sulfur is then used as a sulfur source for a sulfurization reaction to prepare an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive, and its friction performance when used in lubricating oil is effectively improved.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0007] The present invention provides a method for preparing an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive, comprising the following steps:

[0008] S1: In parts by weight, 3 to 5 parts of a water-soluble nickel salt and 0.4 to 0.6 parts of a water-soluble magnesium salt are dissolved in 180 to 200 parts of deionized water to form a solution A, 6 to 8 parts of sodium hydroxide and 4 to 6 parts of sodium carbonate are dissolved in 240 to 260 parts of deionized water to form a solution B, 1 to 3 parts of boron nitride are dispersed in 100 to 120 parts of deionized water, and then the solution A and solution B are added for aging reaction to obtain an LDH precursor;

[0009] S2: The precursor is subjected to sulfurization treatment using sublimed sulfur to obtain an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive.

[0010] As a preferred technical solution of the present invention, the weight proportion of the water-soluble nickel salt can be 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts.

[0011] As a preferred technical solution of the present invention, the weight proportion of the water-soluble magnesium salt can be 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts or 0.6 parts, etc.

[0012] As a preferred technical solution of the present invention, the weight parts of the sodium hydroxide can be 6 parts, 6.5 parts, 7 parts, 7.5 parts or 8 parts.

[0013] As a preferred technical solution of the present invention, the weight proportions of the sodium carbonate can be 4 parts, 4.5 parts, 5 parts, 5.5 parts or 6 parts.

[0014] As a preferred technical solution of the present invention, the weight proportion of the boron nitride can be 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0015] As a preferred technical solution of the present invention, the boron nitride is modified boron nitride;

[0016] The preparation method of the modified boron nitride includes: hydroxylating commercially available boron nitride (particle size of 50 to 200 nm), dispersing the obtained boron nitride in an ethanol solution to form a boron nitride dispersion, adjusting the pH to 8.6 to 8.8 with aqueous ammonia, adding tetraethyl orthosilicate for gelation to obtain a colloidal solution, adding 3-aminopropyltriethoxysilane for coupling treatment to obtain hybrid boron nitride; and adding the hybrid boron nitride and sodium oleate into water for a hydrothermal reaction to obtain the modified boron nitride.

[0017] As a preferred technical solution of the present invention, the hydroxylation step includes: adding 4 to 6 parts of commercially available boron nitride, by weight, to a mixture of 30 to 36 parts of sulfuric acid, 10 to 12 parts of hydrochloric acid and 80 to 100 parts of deionized water, ultrasonically dispersing for 20 to 30 minutes, heating to 110 to 120° C., stirring for 5 to 7 hours, drying, and grinding.

[0018] As a preferred technical solution of the present invention, the gelling treatment step includes: dissolving 20 to 30 parts of tetraethyl orthosilicate in 200 to 240 parts of anhydrous ethanol, then adding the solution to the boron nitride dispersion, ultrasonically dispersing the solution for 50 to 60 minutes, and then stirring the solution at room temperature for 18 to 20 hours to obtain a colloidal solution.

[0019] As a preferred technical solution of the present invention, the coupling treatment step includes: adding 0.3 to 0.5 parts of 3-aminopropyltriethoxysilane to a mixture of 10 to 12 parts of anhydrous ethanol and 10 to 12 parts of acetic acid to fully dissolve it, then adding it to the colloidal liquid, stirring at room temperature for 6 to 8 hours, centrifuging, washing with anhydrous ethanol, and vacuum drying.

[0020] As a preferred technical solution of the present invention, the hydrothermal reaction step includes: adding 6 to 8 parts of sodium oleate to 80 to 100 parts of deionized water, stirring at 80 to 90° C. for 50 to 60 minutes, then adding 1 to 3 parts of the hybrid boron nitride, transferring to a hydrothermal reactor, hydrothermally reacting at 170 to 180° C. for 6 to 8 hours, filtering, washing with water, and drying.

[0021] The invention first modifies boron nitride with hydroxylated functional groups by a strong acid oxidation method. After the acidification treatment, the surface of the boron nitride has a certain number of hydroxyl functional groups and the boron nitride itself has a large specific surface area, which provides excellent reaction sites for the fixation and growth of silicon cores. Then, based on a sol-gel chemical covalent modification method, a silane precursor reacts with the hydroxyl groups generated on the surface of the boron nitride by acidification to form a covalent bond. Subsequently, a silicon source undergoes a self-condensation reaction to generate nano-sized silicon dioxide. Simultaneously, 3-aminopropyltriethoxysilane is added to further couple the nano-silicon dioxide with the hydroxylated boron nitride nanosheets, thereby realizing the modification of silicon dioxide nanoparticles on the surface of the boron nitride to form hybrid boron nitride. Finally, under hydrothermal reaction conditions, the boron nitride can form active sites and combine with sodium oleate, thereby realizing long carbon modification of the boron nitride (long carbon chain modification can provide a steric effect and reduce the aggregation of boron nitride sheets), thereby obtaining modified boron nitride.

[0022] As a preferred technical solution of the present invention, the water-soluble nickel salt is selected from one or more of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.

[0023] As a preferred technical solution of the present invention, the water-soluble nickel salt is nickel nitrate.

[0024] As a preferred technical solution of the present invention, the water-soluble magnesium salt is selected from one or more of magnesium chloride, magnesium sulfate, magnesium nitrate, and magnesium acetate.

[0025] As a preferred technical solution of the present invention, the water-soluble magnesium salt is magnesium chloride.

[0026] As a preferred technical solution of the present invention, the conditions for the aging reaction in step S1 include: adjusting the pH to 10.2-10.4, aging at room temperature for 10-12 hours, filtering, washing with water, and vacuum drying at 60-70°C for 16-20 hours.

[0027] As a preferred technical solution of the present invention, the conditions for the vulcanization treatment in step S2 include: placing in a nitrogen atmosphere and adding sublimed sulfur, heating to 440-460° C. at a rate of 1° C. / min and vulcanizing for 100-120 minutes.

[0028] The present invention uses nickel nitrate and magnesium chloride as metal sources. The nickel nitrate and magnesium chloride are first dissolved in deionized water, and the pH is adjusted so that the metal elements are loaded on the surface of boron nitride to obtain an LDH precursor. Then, sublimed sulfur is used as a sulfur source to carry out a sulfurization reaction. In a nitrogen atmosphere, the metal cations react with sulfur to generate sulfide, thereby preparing an LDH-derived bimetallic sulfide composite boron nitride.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The LDH precursor of the present invention contains two metal cations. After sulfidation, the metal cations are converted into sulfides to form uniform bimetallic active sites, thereby enhancing the extreme pressure and anti-wear properties. At the same time, the LDH precursor is easily peeled off into ultra-thin nanosheets during the sulfidation process. Compared with traditional mechanically mixed sulfides, it has a larger specific surface area and more active sites, and has a stronger adsorption capacity on the friction surface. The layered structure of the bimetallic sulfide derived from LDH and boron nitride can form a composite structure, thereby enhancing the coverage density of the friction interface and reducing direct metal contact, thereby improving the friction performance.

[0031] (2) The modified boron nitride of the present invention has a flaky shape and a small size, which makes it easy for them to enter the friction contact surface. After entering the friction contact surface, boron nitride, as a multi-layer two-dimensional material, is prone to shearing between layers, forming a sliding system under friction contact. Since the friction in the sliding system is much lower, effective lubrication can be achieved; silica nanoparticles can fill the tiny depressions on the friction surface and improve the smoothness of the surface. The smooth surface reduces the local contact pressure and avoids local stress concentration; the boron nitride preferentially contacts the metal surface to reduce direct friction, and the silica disperses the stress to prevent local peeling, which effectively improves the friction performance of the lubricant.

[0032] (3) The oxygen-containing functional groups introduced into the surface of the modified boron nitride of the present invention are used to load nano-metals, so that the metal elements of the water-soluble nickel salt and magnesium salt are better attached to the surface of the boron nitride, which is conducive to the formation of metal sulfides on the surface of the boron nitride. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 is the wear scar diameter of the friction performance test in Application Example 1.

[0035] Figure 2 is the wear scar diameter of the friction performance test in Application Example 8. DETAILED DESCRIPTION

[0036] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0037] The sources of some components in the Examples and Comparative Examples are as follows:

[0038] Boron nitride I, product number B140007, particle size 100 nm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0039] Boron nitride II, product number B106032, particle size 1 μm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0040] Nickel nitrate, CAS No. 13478-00-7, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0041] Magnesium chloride, CAS No. 7786-30-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0042] Sodium hydroxide, CAS No. 1310-73-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0043] Sodium carbonate, CAS No. 497-19-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0044] Sublimed sulfur, CAS No. 7704-34-9, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0045] Tetraethyl orthosilicate, CAS No. 78-10-4, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0046] 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0047] Sodium oleate, CAS No. 143-19-1, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0048] Example 1

[0049] This embodiment provides a method for preparing an LDH-derived bimetallic sulfide composite boron nitride lubricant additive, comprising the following steps:

[0050] S1: In parts by weight, 5 parts of nickel nitrate and 0.6 parts of magnesium chloride were dissolved in 200 parts of deionized water to form a solution A, 8 parts of sodium hydroxide and 6 parts of sodium carbonate were dissolved in 260 parts of deionized water to form a solution B, 3 parts of modified boron nitride were dispersed in 120 parts of deionized water, and then the solution A and solution B were added to carry out an aging reaction, the pH was adjusted to 10.4, aged at room temperature for 12 hours, filtered, washed with water, and vacuum dried at 70°C for 16 hours to obtain an LDH precursor;

[0051] S2: placing the precursor under a nitrogen atmosphere and adding 30 parts of sublimed sulfur, heating to 460° C. at a rate of 1° C. / min and sulfurizing for 100 min to obtain an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive.

[0052] Preparation of the modified boron nitride: 6 parts by weight of commercially available boron nitride I (article number B140007, particle size 100 nm) are added to a mixture of 36 parts of sulfuric acid, 12 parts of hydrochloric acid and 100 parts of deionized water, ultrasonically dispersed for 30 minutes, heated to 120°C and stirred for 5 hours, dried, and ground to obtain hydroxylated boron nitride; the hydroxylated boron nitride is dispersed in an ethanol solution to form a boron nitride dispersion, the pH is adjusted to 8.8 with ammonia water, 30 parts of tetraethyl orthosilicate are dissolved in 240 parts of anhydrous ethanol, and then added to the boron nitride dispersion, ultrasonically dispersed for 60 minutes, and the mixture is stirred for 5 hours. min, and then stirred at room temperature for 20 hours to obtain a colloidal liquid; 0.5 parts of 3-aminopropyltriethoxysilane was added to a mixture of 12 parts of anhydrous ethanol and 12 parts of acetic acid, and fully dissolved, and then added to the colloidal liquid, stirred at room temperature for 8 hours, centrifuged, washed with anhydrous ethanol, and vacuum dried to obtain hybrid boron nitride; 8 parts of sodium oleate were added to 100 parts of deionized water, stirred at 90°C for 50 minutes, and then 3 parts of the hybrid boron nitride were added, transferred to a hydrothermal reactor, hydrothermally reacted at 180°C for 6 hours, filtered, washed with water, and dried to obtain modified boron nitride.

[0053] Example 2

[0054] This embodiment provides a method for preparing an LDH-derived bimetallic sulfide composite boron nitride lubricant additive, comprising the following steps:

[0055] S1: In parts by weight, 3 parts of nickel nitrate and 0.4 parts of magnesium chloride were dissolved in 180 parts of deionized water to form a solution A, 6 parts of sodium hydroxide and 4 parts of sodium carbonate were dissolved in 240 parts of deionized water to form a solution B, 1 part of modified boron nitride was dispersed in 100 parts of deionized water, and then the solution A and solution B were added to carry out an aging reaction, the pH was adjusted to 10.2, aged at room temperature for 10 hours, filtered, washed with water, and vacuum dried at 60°C for 20 hours to obtain an LDH precursor;

[0056] S2: placing the precursor under a nitrogen atmosphere and adding 20 parts of sublimed sulfur, heating to 440° C. at a rate of 1° C. / min and sulfurizing for 120 min to obtain an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive.

[0057] Preparation of the modified boron nitride: 4 parts by weight of commercially available boron nitride I (article number B140007, particle size 100 nm) are added to a mixture of 30 parts of sulfuric acid, 10 parts of hydrochloric acid and 80 parts of deionized water, and ultrasonically dispersed for 20 minutes, heated to 110° C. and stirred for 7 hours, dried, and ground to obtain hydroxylated boron nitride; the hydroxylated boron nitride is dispersed in an ethanol solution to form a boron nitride dispersion, the pH is adjusted to 8.6 with aqueous ammonia, 20 parts of tetraethyl orthosilicate are dissolved in 200 parts of anhydrous ethanol, and then added to the boron nitride dispersion, and ultrasonically dispersed for 50 minutes. min, and then stirred at room temperature for 20 hours to obtain a colloidal liquid; 0.3 parts of 3-aminopropyltriethoxysilane was added to a mixture of 10 parts of anhydrous ethanol and 10 parts of acetic acid, and fully dissolved, and then added to the colloidal liquid, stirred at room temperature for 6 hours, centrifuged, washed with anhydrous ethanol, and vacuum dried to obtain hybrid boron nitride; 6 parts of sodium oleate were added to 80 parts of deionized water, stirred at 80°C for 60 minutes, and then 1 part of the hybrid boron nitride was added, transferred to a hydrothermal reactor, hydrothermally reacted at 170°C for 8 hours, filtered, washed with water, and dried to obtain modified boron nitride.

[0058] Example 3

[0059] This embodiment provides a method for preparing an LDH-derived bimetallic sulfide composite boron nitride lubricant additive, comprising the following steps:

[0060] S1: In parts by weight, 4 parts of nickel nitrate and 0.5 parts of magnesium chloride were dissolved in 190 parts of deionized water to form a solution A, 7 parts of sodium hydroxide and 5 parts of sodium carbonate were dissolved in 250 parts of deionized water to form a solution B, 2 parts of modified boron nitride were dispersed in 110 parts of deionized water, and then the solution A and solution B were added to carry out an aging reaction, the pH was adjusted to 10.3, aged at room temperature for 11 hours, filtered, washed with water, and vacuum dried at 65°C for 18 hours to obtain an LDH precursor;

[0061] S2: placing the precursor under a nitrogen atmosphere and adding 25 parts of sublimed sulfur, heating to 450° C. at a rate of 1° C. / min and sulfurizing for 110 min to obtain an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive.

[0062] Preparation of the modified boron nitride: 5 parts by weight of commercially available boron nitride I (article number B140007, particle size 100 nm) are added to a mixture of 33 parts of sulfuric acid, 11 parts of hydrochloric acid and 90 parts of deionized water, and ultrasonically dispersed for 25 minutes, heated to 115°C and stirred for 6 hours, dried, and ground to obtain hydroxylated boron nitride; the hydroxylated boron nitride is dispersed in an ethanol solution to form a boron nitride dispersion, the pH is adjusted to 8.7 with ammonia water, 25 parts of tetraethyl orthosilicate are dissolved in 220 parts of anhydrous ethanol, and then added to the boron nitride dispersion, and ultrasonically dispersed for 55 minutes. min, and then stirred at room temperature for 19 hours to obtain a colloidal liquid; 0.4 parts of 3-aminopropyltriethoxysilane was added to a mixture of 11 parts of anhydrous ethanol and 11 parts of acetic acid, and fully dissolved, and then added to the colloidal liquid, stirred at room temperature for 7 hours, centrifuged, washed with anhydrous ethanol, and vacuum dried to obtain hybrid boron nitride; 7 parts of sodium oleate were added to 90 parts of deionized water, stirred at 85°C for 55 minutes, and then 2 parts of the hybrid boron nitride were added, transferred to a hydrothermal reactor, hydrothermally reacted at 175°C for 7 hours, filtered, washed with water, and dried to obtain modified boron nitride.

[0063] Example 4

[0064] The difference between this embodiment and embodiment 1 is that boron nitride I (article number B140007, particle size of 100 nm) is used instead of modified boron nitride.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that boron nitride II (article number B106032, particle size 1 μm) is used instead of boron nitride I (article number B140007, particle size 100 nm) to prepare the modified boron nitride.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that boron nitride II (product number B106032, particle size 1 μm) is used instead of modified boron nitride.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that in step S2 , no sublimed sulfur is used for the sulfurization treatment, and the temperature is directly raised to 460° C. at a rate of 1° C. / min for heat treatment for 100 min.

[0071] Preparation of the application example: 60 g of commercially available gear oil and 0.1 wt% of lubricating oil additive were placed in the stainless steel barrel of a ball mill. A tetrafluoroethylene frosted dispersion disk was used and zirconium beads were added to the barrel. After connection, condensation water was turned on, the ball mill was turned on, and the speed was gradually adjusted to 4000 r / min and stirred continuously for 6 hours. After the end, the lubricating oil was filtered using a sieve.

[0072] The friction performance of the lubricating oil provided in the above application example is tested. The specific test method is as follows:

[0073] Friction performance test: Referring to "SH / T 0189-2017 Determination of Anti-wear Performance of Lubricants - Four-ball Method", the test was carried out using a four-ball tribometer. Three steel balls with a diameter of 12.7 mm were clamped in an oil box and covered with the above-mentioned lubricating oil. Another steel ball with a diameter of 12.7 mm was placed on top of the three balls and subjected to a force of 392 N, forming a "three-point contact". When the lubricating oil temperature reached 75°C, the top ball was rotated at a speed of 1200 r / min for 60 minutes. The wear spot diameters of the three lower steel balls were measured, and the average value of the wear spot diameters was taken as the average wear scar diameter. At the same time, the friction coefficient was calculated.

[0074] The above performance test data is shown in Table 1.

[0075] Table 1 Performance test results

[0076]

[0077]

[0078] From the above content, it can be seen that the present invention uses nickel nitrate and magnesium chloride as metal sources, loads the metal elements on the surface of boron nitride through an aging reaction to form an LDH precursor, and then uses sublimated sulfur as a sulfur source to carry out a sulfurization reaction to prepare an LDH-derived bimetallic sulfide composite boron nitride lubricant additive, which is then mixed with commercially available gear oil to obtain a lubricant with better comprehensive performance (Application Examples 1 to 3).

[0079] Compared with Application Example 1, boron nitride I (article number B140007, particle size of 100 nm) is used instead of modified boron nitride. Due to the lack of long carbon modification and hybridization of silica nanoparticles in boron nitride, the friction performance of the lubricating oil deteriorates (Application Example 4); Compared with Example 1, boron nitride II (article number B106032, particle size of 1 μm) is used instead of boron nitride I (article number B140007, particle size of 100 nm) for the preparation of modified boron nitride. Due to the large particle size of boron nitride II, the modification effect is not good, and the friction performance of the lubricating oil deteriorates (Application Example 5); Compared with Application Example 1, boron nitride II (article number B106032, particle size of 1 μm) is used instead of modified boron nitride. Boron nitride, due to the lack of long carbon modification and hybridization of silica nanoparticles in boron nitride, and the excessively large particle size of boron nitride II, the friction performance of the lubricating oil deteriorates (Application Example 6); compared with Application Example 1, in step S2, no sublimed sulfur is used for sulfurization treatment, and the temperature is directly raised to 460°C at a rate of 1°C / min for 100 minutes. Due to the lack of LDH-derived bimetallic sulfide, the friction performance of the lubricating oil deteriorates (Application Example 7); compared with Application Example 1, 0.1wt% boron nitride is used instead of 0.1wt% lubricating oil additive. Due to the lack of the combined effect of LDH-derived bimetallic sulfide and modified boron nitride, the friction performance of the lubricating oil deteriorates (Application Example 8), for details, please refer to Figure 2 .

Claims

1. A method for preparing an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive, characterized in that: The following steps are involved: S1: In parts by weight, 3 to 5 parts of a water-soluble nickel salt and 0.4 to 0.6 parts of a water-soluble magnesium salt are dissolved in 180 to 200 parts of deionized water to form a solution A, 6 to 8 parts of sodium hydroxide and 4 to 6 parts of sodium carbonate are dissolved in 240 to 260 parts of deionized water to form a solution B, 1 to 3 parts of boron nitride are dispersed in 100 to 120 parts of deionized water, and then the solution A and solution B are added for aging reaction to obtain an LDH precursor; S2: The precursor is subjected to sulfurization treatment using sublimed sulfur to obtain an LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive.

2. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 1, characterized in that: The boron nitride is modified boron nitride; The preparation method of the modified boron nitride includes: hydroxylating commercially available boron nitride (particle size of 50 to 200 nm), dispersing the obtained boron nitride in an ethanol solution to form a boron nitride dispersion, adjusting the pH to 8.6 to 8.8 with aqueous ammonia, adding tetraethyl orthosilicate for gelation to obtain a colloidal solution, adding 3-aminopropyltriethoxysilane for coupling treatment to obtain hybrid boron nitride; and adding the hybrid boron nitride and sodium oleate into water for a hydrothermal reaction to obtain the modified boron nitride.

3. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 2, characterized in that: The hydroxylation step comprises: adding 4 to 6 parts of commercially available boron nitride by weight to a mixture of 30 to 36 parts of sulfuric acid, 10 to 12 parts of hydrochloric acid and 80 to 100 parts of deionized water, ultrasonically dispersing for 20 to 30 minutes, heating to 110 to 120° C., stirring for 5 to 7 hours, drying, and grinding.

4. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 2, characterized in that: The gelling treatment step includes: dissolving 20 to 30 parts of tetraethyl orthosilicate in 200 to 240 parts of anhydrous ethanol, then adding the solution to the boron nitride dispersion, ultrasonically dispersing the solution for 50 to 60 minutes, and then stirring the solution at room temperature for 18 to 20 hours to obtain a colloidal solution.

5. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 2, characterized in that: The coupling treatment step includes: adding 0.3-0.5 parts of 3-aminopropyltriethoxysilane to a mixture of 10-12 parts of anhydrous ethanol and 10-12 parts of acetic acid to fully dissolve the mixture, then adding the mixture to the colloidal solution, stirring at room temperature for 6-8 hours, centrifuging, washing with anhydrous ethanol, and vacuum drying.

6. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 2, characterized in that: The hydrothermal reaction step includes: adding 6 to 8 parts of sodium oleate to 80 to 100 parts of deionized water, stirring at 80 to 90° C. for 50 to 60 minutes, then adding 1 to 3 parts of the hybrid boron nitride, transferring to a hydrothermal reactor, hydrothermally reacting at 170 to 180° C. for 6 to 8 hours, filtering, washing with water, and drying.

7. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 1, characterized in that: The water-soluble nickel salt is nickel nitrate.

8. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 1, characterized in that: The water-soluble magnesium salt is magnesium chloride.

9. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 1, characterized in that: The aging reaction conditions in step S1 include: adjusting the pH to 10.2-10.4, aging at room temperature for 10-12 hours, filtering, washing with water, and vacuum drying at 60-70° C. for 16-20 hours.

10. The method for preparing a LDH-derived bimetallic sulfide composite boron nitride lubricating oil additive according to claim 1, characterized in that: The conditions for the vulcanization treatment in step S2 include: placing the material under a nitrogen atmosphere and adding sublimed sulfur, heating the material to 440-460° C. at a rate of 1° C. / min and vulcanizing the material for 100-120 minutes.

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