Preparation and test method of sulfur-containing carbon nitride water lubricant based on white spirit hydrothermal method

Abstract

According to the preparation method of the sulfur-containing carbon nitride water lubricant based on the Baijiu hydrothermal method, materials for preparing the sulfur-containing carbon nitride water lubricant comprise thiourea and an ethanol-water mixed solution, and the preparation of the sulfur-containing carbon nitride water lubricant based on the Baijiu hydrothermal method comprises two processes. In the method for testing the sulfur-containing carbon nitride water lubricant based on the white spirit hydrothermal method, a high-speed ring-block friction testing machine is selected as specific testing equipment, and an experimental polymer material is polyphenylene sulfide. The method has the remarkable advantages of simple and convenient preparation process, lower energy consumption and short production period; the sulfur-containing carbon nitride water lubricant has the characteristics of smaller size and more stable storage, can show excellent lubrication and wear resistance when elements such as an engineering plastic-based sliding block, a shaft sleeve or a sealing ring and the like are in friction with stainless steel, and has a remarkable improvement effect on the tribological performance of a polyphenylene sulfide-stainless steel matching pair; and the wear resistance of related mechanisms and the service life of equipment are improved when the device is applied to terminals. In conclusion, the method has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of water lubricants, in particular to a preparation and testing method of a sulfur-containing carbon nitride water lubricant based on a liquor hydrothermal method. Background Art

[0002] In a fluid lubrication system, the load-bearing capacity of the lubricating film is proportional to the viscosity of the lubricating fluid and inversely proportional to the square of the film thickness. Water is a low-viscosity liquid, so it is not easy to form a water film when used as a lubricant. In some harsh conditions, water lubrication hardly produces a fluid lubrication effect, resulting in low load-bearing capacity of water-lubricated bearings. This causes water-lubricated bearings operating under non-fluid lubrication conditions to come into direct contact with the journal, causing severe wear and even journal burnout. Adding an additive-type water lubricant with easy transfer and good film-forming properties to water is an effective strategy to solve the above problems. The addition of additives to water helps to form a lubricating protective film at the interface, avoiding direct contact between the bearing and the journal, thereby fundamentally preventing the occurrence of serious accidents such as seizure and even journal burnout.

[0003] With the development of technology, the performance of water lubricants has also been greatly improved. For example, my country's patent application with patent number "201210027265.1" and titled "A graphene oxide-fullerene water-based lubricant" solves the technical problems of existing water lubricants such as high cost, poor stability and low lubrication performance through its technical solution; the patent application with patent number "201410212428.2" and titled "Water-based graphene-molybdenum disulfide nanotube lubricant" functionalizes graphene and molybdenum disulfide nanotubes separately to make them water-soluble, and then compounds them in a certain proportion to prepare a finished product with the advantages of high stability, good lubrication performance and low pollution; the patent application with patent number "201510504476.3" and titled "Graphene oxide-polymer microsphere water-based lubricant" technically mixes graphene oxide powder and polymer microsphere emulsion, and uses ultrasonic vibration to fully disperse the graphene oxide powder in the emulsion. The finished product has multiple functional advantages such as cooling, rust prevention and corrosion inhibition. Although the above-mentioned technical solutions have achieved the technical effects of the inventions described therein, they are limited by materials and preparation processes. During production, many raw materials have poor water solubility and are relatively easy to come into contact with oxygen in the air, which causes high-temperature oxidation of the raw materials and adversely affects their lubricity. In addition, the above-mentioned technical solutions also have disadvantages such as relatively high raw material costs, complex preparation processes, and difficulty in large-scale production.

[0004] In the prior art, improvements have been made to carbon nitride-based water lubricants in the applications for patent number "201910073191.7" and patent number "201910073806.6". However, due to technical limitations, the calcined carbon nitride is directly hydrothermally treated with water as a solvent to be used as a water-soluble carbon nitride water lubricant, which will cause the particles in the sol to be too large and ultimately lead to insufficient lubrication performance. There are also problems with the secondary physical mixing of the lubricating component ionic liquid, which has poor compatibility and whether it can be stably preserved for a long time. In practical applications, for hydrothermal reactions, pure water is used as the solvent. Under normal pressure, water needs to be heated to 100°C to boil and generate a certain vapor pressure. However, the hydrothermal reaction is carried out in a closed space, and a higher temperature must be provided to make the water boil. Therefore, when water is used as the solvent, the hydrothermal temperature must be high, resulting in high energy consumption. In addition, due to the low vapor pressure, the structure of the hydrothermal product carbon nitride tends to be compact and not fluffy, resulting in a large particle size of the obtained carbon nitride material. When large-sized carbon nitride is used as a solute to form a sol in water, it is difficult to disperse and preserve stably for a long time. Therefore, it is undoubtedly a more efficient preparation strategy and idea to reduce the size of the solute in the hydrothermally synthesized carbon nitride-based water lubricant and make the structure fluffy while reducing the energy consumption of the preparation process by certain technical means. However, there is no perfect technical solution in the existing technology, so it is particularly necessary to provide a technology that can solve the problems of carbon nitride-based water lubricants. Summary of the Invention

[0005] In order to overcome the drawbacks of the existing carbon nitride-based water lubricants due to the limitations of preparation materials and preparation processes, the prepared finished products have the drawbacks as described in the background technology, the present invention provides a simple preparation process, lower energy consumption, and significantly shortened production cycle. The prepared finished products have excellent lubrication and wear resistance, as well as the characteristics of being green and environmentally friendly, harmless to the human body, and can be stored stably for a long time. Compared with the sulfur-containing carbon nitride water lubricant prepared using pure water as the hydrothermal solvent, it has the characteristics of smaller size and more stable storage. It can show excellent lubrication and wear resistance when rubbing against engineering plastic-based sliders, bushings or sealing rings and other components with stainless steel. The friction coefficient can be reduced from 0.32 to 0.20, thereby improving the wear resistance of related mechanisms and the service life of equipment. Preparation and testing method of sulfur-containing carbon nitride water lubricant based on white wine hydrothermal method.

[0006] The technical solution adopted by the present invention to solve its technical problem is: A method for preparing a sulfur-containing carbon nitride aqueous lubricant based on a liquor hydrothermal method, wherein the materials of the sulfur-containing carbon nitride aqueous lubricant include thiourea and an ethanol-water mixture, wherein the amount of thiourea is 4g~6g, and the proportion of ethanol in the ethanol-water mixture is 30%~70%; the preparation process of the sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method is as follows: S1: weighing thiourea and dispersing it in an ethanol-water mixture containing ethanol at room temperature, stirring and dissolving it thoroughly, and then transferring it to a hydrothermal reactor with a polytetrafluoroethylene lining; S2: tightening the lid of the hydrothermal reactor to seal it, placing it in a constant temperature oven for a certain period of time, and naturally cooling it to obtain the sulfur-containing carbon nitride aqueous lubricant; The test method for the sulfur-containing carbon nitride water lubricant prepared by the white wine hydrothermal method is as follows. The specific test equipment is a high-speed ring-block friction tester. The polymer material of the experiment is one of polyetheretherketone, polyimide, polyphenylene sulfide, and polyoxymethylene engineering plastic raw materials. The metal ring used in the friction experiment with the engineering plastic raw material is a stainless steel metal ring with a surface roughness of 0.1-0.8μm. The test conditions for the effect of the sulfur-containing carbon nitride water lubricant prepared by the white wine hydrothermal method on the tribological properties of the above-mentioned pair are: load 100N, rotation speed 0.5m / s, test time 2h, and the water lubricant is injected into the friction interface drop by drop at a dripping rate of 2mL / h.

[0007] Furthermore, in the preparation method of the sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method, the temperature of the ethanol-water mixture is between 20°C and 30°C, preferably 25°C.

[0008] Furthermore, in the preparation method of the sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method, liquor can also be used instead of the ethanol-water mixture.

[0009] Furthermore, in the preparation method of the sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method, the mass mixing ratio of thiourea and ethanol-water mixture is between 1:(1:4) and 1:(4:1).

[0010] Furthermore, in the preparation method of sulfur-containing carbon nitride water lubricant based on the white wine hydrothermal method, the oven temperature during hydrothermal treatment is 100~250℃, and the hydrothermal time is 1~3 hours.

[0011] Furthermore, in the preparation method of the sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method, ethanol-water solution or liquor is used as a solvent, which can reduce the size of carbon nitride, form a fluffy structure and reduce energy consumption. Specifically, compared with pure water, ethanol has a larger expansion coefficient, can form a higher vapor pressure in the kettle when hydrothermally heated at the same temperature, can make the carbon nitride form a more fluffy layered structure under the same conditions, and can effectively reduce the particle size of carbon nitride and increase its specific surface area, thereby fundamentally improving its more uniform and stable dispersion in water, promoting the prepared carbon nitride aqueous lubricant to exhibit better lubrication and wear resistance, and can exert good lubrication performance in terminal applications.

[0012] Furthermore, in the test of the sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method, pure water was used instead of the ethanol-water mixture, and the hydrothermal reaction was carried out under the same conditions to obtain a comparative sulfur-containing carbon nitride aqueous lubricant.

[0013] Furthermore, in the test of sulfur-containing carbon nitride water lubricant based on the liquor hydrothermal method, the water lubricant is dripped drop by drop between the running friction pairs in a line-surface and surface-surface contact manner, which can better simulate the working conditions of the workpiece and achieve better detection purposes.

[0014] Compared with the prior art, the present invention has the following advantages: (1) the present invention has the significant advantages of simple preparation process, lower energy consumption and short production cycle; (2) it has smaller size and more stable storage characteristics than the sulfur-containing carbon nitride water lubricant prepared by using pure water as the hydrothermal solvent; (3) the prepared sulfur-containing carbon nitride water lubricant can show excellent lubrication and wear resistance when components such as engineering plastic-based sliders, sleeves or sealing rings are rubbed against stainless steel. Compared with the sulfur-containing carbon nitride water lubricant prepared by using pure water as the hydrothermal solvent, the water lubricant prepared by using ethanol-water mixture hydrothermal method has a significant improvement on the tribological properties of polyphenylene sulfide-stainless steel pairing, and the friction coefficient can be reduced from 0.32 to 0.20. At the same time, the wear resistance (i.e., service life) of polyphenylene sulfide can be improved by about 55%, thereby improving the wear resistance of related mechanisms and the service life of equipment. In summary, the present invention has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention shows the XRD spectra of sulfur-containing carbon nitride aqueous lubricants prepared by using ethanol-water in different ratios.

[0016] Figure 2 Schematic diagram of the friction coefficient (a) and wear rate (b) of polyphenylene sulfide-stainless steel ring friction in the test of the present invention. DETAILED DESCRIPTION

[0017] A method for preparing a sulfur-containing carbon nitride aqueous lubricant based on a liquor hydrothermal method, wherein the materials of the sulfur-containing carbon nitride aqueous lubricant include thiourea and an ethanol-water mixture. Example 1: 50g of pure water and 50g of anhydrous ethanol are weighed and stirred uniformly at room temperature to obtain an ethanol-water mixture containing 50% ethanol, equivalent to liquor with an alcohol content of approximately 50%. 5g of white solid thiourea is then weighed and transferred to 20mL of the ethanol-water mixture, thoroughly stirred and dissolved. The mixture is then transferred to a 50mL polytetrafluoroethylene-lined hydrothermal autoclave, placed in a 120°C oven, and maintained for 2 hours. After natural cooling, sulfur-containing carbon nitride aqueous lubricant 1 is obtained. Example 2: 30g of pure water and 70g of anhydrous ethanol were weighed and stirred at room temperature to obtain an ethanol-water mixture containing 70% ethanol, equivalent to a white spirit with an alcohol content of approximately 70%. 5g of white solid thiourea was then weighed and transferred to 20mL of the ethanol-water mixture, thoroughly stirred and dissolved. The mixture was then transferred to a 50mL polytetrafluoroethylene-lined hydrothermal reactor and incubated in a 120°C oven for 2 hours. After natural cooling, sulfur-containing carbon nitride aqueous lubricant 2 was obtained. Example 3: 70g of pure water and 30g of anhydrous ethanol were weighed and stirred at room temperature to obtain an ethanol-water mixture containing 70% ethanol, equivalent to a white spirit with an alcohol content of approximately 30%. 5g of white solid thiourea was then weighed and transferred to 20mL of the ethanol-water mixture, thoroughly stirred and dissolved. The mixture was then transferred to a 50mL polytetrafluoroethylene-lined hydrothermal reactor and incubated in a 120°C oven for 2 hours. After natural cooling, sulfur-containing carbon nitride aqueous lubricant 3 is obtained. Specifically, the temperature of the ethanol-water mixture is between 20°C and 30°C, preferably 25°C; white wine can also be used instead of the ethanol-water mixture; the mass mixing ratio of thiourea to the ethanol-water mixture is between 1:(1:4) and 1:(4:1), preferably 1:4; the oven temperature during hydrothermal treatment is 100°C to 250°C, preferably 120°C, and the hydrothermal time is 1 to 3 hours, preferably 2 hours. In the present invention, thiourea (CH4N2S) contains nitrogen and carbon elements and can undergo a condensation reaction to form carbon nitride (C3N4) under high temperature and high pressure hydrothermal conditions. Therefore, thiourea is a raw material for synthesizing carbon nitride, and sulfur-containing carbon nitride aqueous lubricant can be prepared (a certain amount of alcohol is mixed into the water to increase the pressure in the enclosed space of the reactor during hydrothermal treatment).

[0018] In the background art of the present invention, for hydrothermal reactions, pure water is used as the solvent. Under normal pressure, water must be at a temperature of 100°C to boil and generate a certain vapor pressure. However, hydrothermal reactions are carried out in a closed space, and a higher temperature must be provided to make the water boil. Therefore, when water is used as the solvent, the hydrothermal temperature must be high, resulting in high energy consumption. Due to the low vapor pressure, the structure of the hydrothermal product carbon nitride tends to be compact and not fluffy, resulting in a larger particle size of the obtained carbon nitride material. Large-sized carbon nitride, when used as a solute, forms a sol in water, which makes it difficult to disperse and preserve stably for a long time. To address the problems existing in the prior art, the finished product prepared by the present invention uses a certain ratio of ethanol-water solution or white wine as the solvent, which can perfectly reduce the size of the carbon nitride, form a fluffy structure, and reduce energy consumption. The reasons are as follows: (1) Compared with pure water, ethanol has a larger expansion coefficient, can form a higher vapor pressure in the kettle when hydrothermally heated at the same temperature, can make carbon nitride form a more fluffy layered structure under the same conditions, and can effectively reduce the particle size of carbon nitride and increase its specific surface area, thereby fundamentally improving its more uniform and stable dispersion in water, and promoting the carbon nitride water lubricant prepared by this method to exhibit better lubrication and wear resistance. (2) The present invention does not directly use anhydrous ethanol as a solvent. The reason is that compared with anhydrous ethanol (alcohol concentration is above 99.5%), ethanol and water can be miscible in any proportion. After mixing anhydrous ethanol and water in proportion, the safety storage risk of anhydrous ethanol at room temperature can be reduced and its safe transportation and subsequent operation safety can be improved. Therefore, the present invention selects ethanol and water to be miscible in a certain proportion as the hydrothermal solvent of the sulfur-containing carbon nitride water lubricant, and further optimizes the ethanol-water ratio to improve the lubrication performance of the carbon nitride water lubricant, so that the sulfur-containing carbon nitride water lubricant has multiple excellent properties (large expansion coefficient, high vapor pressure, promotion of carbon nitride fluffy structure and uniform and stable dispersion, etc.) and safety (more reliable storage, transportation and operation at room temperature). (3) The sulfur-containing carbon nitride water lubricant directly synthesized by the present invention uses thiourea as the raw material containing sulfur, which has an important promoting effect on further improving the lubrication and wear resistance of the carbon nitride-based water lubricant. In summary, in order to more intuitively highlight the innovation of the present invention, and in combination with the convenience and cost reduction of actual production, the present invention directly uses white wine (i.e., a commercial mixture of ethanol and water) as the hydrothermal solvent, which can perfectly replace the problems existing in the existing technology of anhydrous ethanol-water mixed solvent as a lubricant, and plays a role in reducing energy consumption, increasing vapor pressure, increasing expansion coefficient, and promoting the fluffy structure and uniform and stable dispersion of carbon nitride. At the same time, it also reduces safety risks to the greatest extent. Therefore, the present invention has significant innovations in the preparation strategy of the target product, performance considerations and production safety.

[0019] The test method for sulfur-containing carbon nitride water lubricant based on the liquor hydrothermal method is as follows. The specific test equipment is a high-speed ring-block friction tester. The polymer material used in the experiment is one of polyetheretherketone, polyimide, polyphenylene sulfide, and polyoxymethylene engineering plastic raw materials. The metal ring used in the friction experiment with the engineering plastic raw material is a stainless steel metal ring with a surface roughness of 0.1-0.8μm. The test conditions for the effect of the binary environmentally friendly water lubricant on the tribological properties of the above-mentioned pairings are: load 100N, speed 0.5m / s, test time 2h, and the binary composite environmentally friendly water lubricant is injected into the friction interface drop by drop at a dripping rate of 2mL / h. In the test of sulfur-containing carbon nitride water lubricant based on the liquor hydrothermal method, pure water is used instead of the ethanol-water mixture, and the hydrothermal reaction is carried out under the same conditions to obtain a comparative sulfur-containing carbon nitride water lubricant. In the test of sulfur-containing carbon nitride water lubricant based on the liquor hydrothermal method, the water lubricant is dripped drop by drop between the running friction pairs in a line-surface and surface-surface contact manner, which can better simulate the working conditions of the workpiece and achieve better detection purposes. Compared with the prior art, a low-solid calcium stearate lubricant for papermaking and its preparation method (201610453233.6) and a boron-containing composite calcium sulfonate-based grease composition and its preparation method (201611138422.0), the practicality of the lubrication performance test of the relevant lubricants is not involved and considered. The present invention provides a detailed evaluation method for the lubrication and anti-wear performance of water lubricants that meet actual operating conditions for specific usage scenarios, which significantly improves the practicality and practical application value of the present invention. Specific tests, attached Figure 1 Among them, 0# is the sample after drying of sulfur-containing carbon nitride water lubricant of comparative example, 1# and 2# are the samples after drying of sulfur-containing carbon nitride water lubricant of examples 1 and 2 respectively; Figure 1 It can be seen that the carbon nitride material prepared with ethanol-water mixture or high-proof liquor as hydrothermal solvent has a smaller particle size, because the XRD spectrum is located at 12.8 o The (100) crystal plane intensity gradually decreases to almost disappear, and at the same time it shows that the specific surface area of carbon nitride material increases significantly; o The (002) crystal plane intensity also decreases significantly, indicating that the interlayer spacing is further reduced and the interlayer structure is significantly destroyed, which means that the sulfur-containing carbon nitride prepared has a smaller particle size. Figure 2 In the figure, 0# is a sulfur-containing carbon nitride water lubricant prepared by the comparative example method, 1# and 2# are sulfur-containing carbon nitride water lubricants prepared by the methods of Examples 1 and 2 respectively; Figure 2 It can be seen that compared with the carbon nitride water lubricant prepared by the comparative method, the carbon nitride water lubricant prepared by the methods of Examples 1 and 2 exhibits better lubrication performance on the polyphenylene sulfide-stainless steel ring pair, which indicates that as the specific surface area of the water lubricant increases and the interlayer spacing decreases, its lubrication effect becomes more obvious. Figure 2b It can be seen that compared with the carbon nitride water lubricant prepared by the comparative example method, the carbon nitride water lubricant prepared by the methods of Examples 1 and 2 can make polyphenylene sulfide exhibit more wear-resistant properties, and as the carbon nitride particle size in the water lubricant decreases, it can play a more significant wear-resistant role.

[0020] In summary, the present invention achieves the following technical effects. (1) From the comparison of the water lubricant preparation strategies in the comparative example and Examples 1-3, it can be seen that the sulfur-containing carbon nitride water lubricant preparation process involved in the present invention is more efficient and has lower energy consumption; (2) The carbon nitride water lubricant prepared by the present invention has a smaller size and more stable storage characteristics than the sulfur-containing carbon nitride water lubricant prepared using pure water as the hydrothermal solvent (see Appendix Figure 1 (3) The sulfur-containing carbon nitride water lubricant prepared by the present invention can show excellent lubrication and wear resistance when the components such as engineering plastic-based sliders, sleeves or sealing rings are rubbed against stainless steel. Compared with the sulfur-containing carbon nitride water lubricant prepared by using pure water as the hydrothermal solvent, the water lubricant prepared by using ethanol-water mixture hydrothermally has a significant improvement effect on the tribological properties of polyphenylene sulfide-stainless steel pairing, and the friction coefficient can be reduced from 0.32 to 0.20. At the same time, the wear resistance (i.e. service life) of polyphenylene sulfide can be improved by about 55% (see attached Figure 2 ).

[0021] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded in all respects as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0022] In addition, it should be understood that although this specification is described in terms of implementation methods, the implementation methods do not only include an independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a sulfur-containing carbon nitride aqueous lubricant based on a liquor hydrothermal method, characterized in that: The materials of the sulfur-containing carbon nitride aqueous lubricant include thiourea and an ethanol-water mixture, wherein the amount of thiourea is 4g~6g, and the proportion of ethanol in the ethanol-water mixture is 30%~70%; the preparation process of the sulfur-containing carbon nitride aqueous lubricant by the liquor hydrothermal method is as follows: S1: weigh thiourea and disperse it in an ethanol-water mixture containing ethanol at room temperature, stir it thoroughly to dissolve it, and then transfer it to a hydrothermal reactor with a polytetrafluoroethylene lining; S2: tighten the lid of the hydrothermal reactor and seal it, place it in a constant temperature oven for a certain period of time, and cool it naturally to obtain the sulfur-containing carbon nitride aqueous lubricant; sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method The test method for water lubricant is as follows. The specific test equipment is a high-speed ring-block friction tester. The polymer material of the experiment is one of polyetheretherketone, polyimide, polyphenylene sulfide, and polyoxymethylene engineering plastic raw materials. The metal ring used in the friction experiment with the engineering plastic raw material is a stainless steel metal ring with a surface roughness of 0.1-0.8μm. The test conditions for the effect of sulfur-containing carbon nitride water lubricant on the tribological properties of the above-mentioned pairing based on the white wine hydrothermal method are: load 100N, rotation speed 0.5m / s, test time 2h, and the water lubricant is injected into the friction interface drop by drop at a dripping rate of 2mL / h.

2. The method for preparing sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: The temperature of the ethanol-water mixture is between 20°C and 30°C, preferably 25°C.

3. The method for preparing sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: Liquor can also be used instead of the ethanol-water mixture.

4. The method for preparing sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: The mass mixing ratio of thiourea and ethanol-water mixture is between 1:(1:4) and 1:(4:1).

5. The method for preparing sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: During the hydrothermal treatment, the oven temperature is 100~250℃, and the hydrothermal time is 1~3 hours.

6. The method for preparing sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: Using ethanol-water solution or white wine as a solvent can reduce the size of carbon nitride, form a fluffy structure and reduce energy consumption. Specifically, compared with pure water, ethanol has a larger expansion coefficient, can form a higher vapor pressure in the kettle when hydrothermally heated at the same temperature, can make carbon nitride form a more fluffy layered structure under the same conditions, and can effectively reduce the particle size of carbon nitride and increase its specific surface area, thereby fundamentally improving its more uniform and stable dispersion in water, promoting the prepared carbon nitride water lubricant to exhibit better lubrication and wear resistance, and can exert good lubrication performance in terminal applications.

7. The testing method for sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: Pure water was used instead of the ethanol-water mixture, and the hydrothermal reaction was carried out under the same conditions to obtain a comparative sulfur-containing carbon nitride aqueous lubricant.

8. The testing method for sulfur-containing carbon nitride aqueous lubricant based on the liquor hydrothermal method according to claim 1, characterized in that: Dripping water lubricant drop by drop between the running friction pairs in a line-surface or surface-surface contact manner can better simulate the working conditions of the workpiece and achieve better detection purposes.

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