High-lubrication wear-resistant drawing oil and preparation method thereof adaptive to metal processing

Abstract

The invention belongs to the technical field of metal processing lubrication, and discloses high-lubrication wear-resistant drawing oil and a preparation method of the high-lubrication wear-resistant drawing oil adaptive to metal processing. The stretching oil comprises base oil, a light response type self-cleaning additive, an extreme pressure anti-wear synergist and other functional components, the light response type self-cleaning additive is formed by loading nitrogen-doped titanium dioxide and graphite-phase carbon nitride quantum dots on mesoporous silica, and a residual film can be catalytically degraded into water-soluble micromolecules under visible light. According to the high-lubrication wear-resistant drawing oil and the preparation method thereof, the high-lubrication wear-resistant drawing oil is clear in structure, reliable in performance and environmentally friendly, a light-triggered self-deconstruction mechanism is introduced, and the inherent contradiction between the machining performance and the aftertreatment compatibility of a traditional lubrication system is successfully broken through; and a brand new technical path is provided for a precision aluminum alloy forming and surface treatment integrated process.

Description

Technical Field

[0001] This invention belongs to the field of metalworking lubrication technology, and relates to a high-lubricity, anti-wear, and stretching oil and its preparation method suitable for metalworking. Background Technology

[0002] In the field of modern precision metal processing, aluminum alloys are widely used in aerospace, consumer electronics, and automotive manufacturing industries due to their excellent specific strength, good thermal conductivity, and ductility. The key stretching forming process in its ductility development places extremely high demands on the performance of the lubricating medium.

[0003] Traditional drawing oils typically use mineral oil or synthetic ester as the base oil, adding extreme pressure anti-wear agents, oiliness agents, and rust inhibitors to reduce the coefficient of friction, inhibit die and tool wear, and ensure forming accuracy. This method alleviates the problems of metal surface adhesion and scratches under high loads to some extent, improves processing efficiency and workpiece surface integrity, and has become the mainstream method.

[0004] However, traditional stretching oil systems are prone to thermal oxidation polymerization or adsorption solidification at the stretching interface under high temperature and pressure, forming a dense and chemically inert organic residual film. Although this film provides temporary protection during processing, it is difficult to remove during the subsequent anodizing pretreatment.

[0005] To ensure sufficient bonding strength between the oxide film and the aluminum substrate, strong acids (such as a mixture of nitric acid and hydrofluoric acid) are often used in industrial practice for deep cleaning. This not only increases wastewater treatment costs and equipment corrosion risks, but also contradicts the concepts of green manufacturing and clean production.

[0006] If the amount of high molecular weight or high polarity additives is increased to improve the lubrication effect, the cross-linking density and thermal stability of the residual film will also be enhanced, making it more difficult to remove. If the activity of the additives is deliberately reduced to improve the washability, it will lead to insufficient boundary lubrication in high deformation stretching, causing the workpiece to crack or the mold life to be reduced.

[0007] Traditional stretching oils cannot simultaneously consider both the instantaneous performance during the processing stage and the interfacial stretchability of the material throughout the entire process. Existing lubrication systems cannot actively respond to environmental signals, autonomously decompose, and transform into harmless byproducts after lubrication. Summary of the Invention

[0008] To achieve the above-mentioned objectives, this invention provides a high-lubricity, anti-wear drawing oil and its preparation method suitable for metal processing. The high-lubricity, anti-wear drawing oil exhibits excellent boundary lubrication performance and extreme pressure anti-wear characteristics during aluminum alloy drawing and forming. Simultaneously, the lubrication residue film formed on the workpiece surface can undergo photocatalytic degradation under visible light irradiation, transforming in situ into water-soluble small molecule products. This eliminates the need for subsequent strong acid cleaning processes, significantly improves the efficiency of anodizing pretreatment and coating adhesion, and reduces the industrial wastewater treatment load.

[0009] The high-lubricating, anti-wear, and stretching oil of this invention is composed of the following components in the following mass percentages:

[0010] Base oil 85.0%-92.0%, light-responsive self-cleaning additive 3.0%-8.0%, extreme pressure anti-wear synergist 1.0%-4.0%, antioxidant stabilizer 0.3%-1.0%, metal passivator 0.2%-0.8%, and defoamer 0.1%-0.5%.

[0011] The base oil is selected from hydrotreated mineral oil, polyalphaolefin synthetic oil, or mixtures thereof, and has a kinematic viscosity of 30-60 mmHg at 40°C. 2 / s, pour point below -30℃, flash point above 220℃;

[0012] The photoresponsive self-cleaning additive is a composite photocatalyst system supported on a mesoporous silica support. This system comprises 15%-25% nitrogen-doped titanium dioxide nanocrystals by weight of the support and 5%-10% graphitic carbon nitride quantum dots by weight of the support. The specific surface area of ​​the mesoporous silica support is 600-900 m². 2 / g, with an average pore size of 4-8nm and a particle size distribution of 100-300nm;

[0013] The extreme pressure anti-wear synergist is a compound of tricresyl phosphate and thiophosphate, with a mass ratio of 2:1 to 4:1.

[0014] The antioxidant stabilizer is a combination of 2,6-di-tert-butyl-p-cresol and alkylated diphenylamine, with a mass ratio of 1:1.

[0015] The metal passivating agent is a benzotriazole derivative, specifically 1-hydroxyethylbenzotriazole;

[0016] The defoamer is a polyether-modified siloxane with an HLB value of 3 to 5.

[0017] The preparation method of the photoresponsive self-cleaning additive includes the following steps:

[0018] 1. Tetraethyl orthosilicate is dissolved in anhydrous ethanol and hydrolyzed and condensed at 30°C for 4 hours under the catalysis of ammonia water to form mesoporous silica microspheres with controllable particle size.

[0019] 2. The microspheres are dispersed in deionized water, and a mixed solution of tetrabutyl titanate and urea is added. The mixture is reacted at 80°C for 12 hours under hydrothermal conditions to allow nitrogen-doped titanium dioxide nanocrystals to grow in situ on the inner wall of the pores.

[0020] 3. The obtained material is immersed in an ethanol dispersion of graphite-phase carbon nitride quantum dots and dried under vacuum at 60°C for 6 hours, so that the quantum dots are anchored to the outer surface of the carrier by electrostatic adsorption, forming a composite structure with dual active centers.

[0021] The average particle size of the graphitic carbon nitride quantum dots is 3-5 nm, and its band gap width is 2.4 eV to 2.7 eV, which can effectively absorb visible light in the wavelength range of 450-520 nm.

[0022] In a preferred embodiment of the present invention, the preparation method of the high-lubricity, anti-wear, and stretching oil includes the following process flow:

[0023] 1. Preheat the base oil to 60°C, and add the extreme pressure anti-wear synergist, antioxidant stabilizer, metal passivator and defoamer in sequence under stirring. Stir at a constant temperature for 30 minutes to fully dissolve all components.

[0024] 2. The photoresponsive self-cleaning additive was slowly added to the above mixture in powder form, and high-speed shearing emulsification was carried out at 80°C and 1500 rpm for 60 minutes to ensure that the nanoparticles were uniformly dispersed and free from agglomeration.

[0025] 3. The finished stretching oil is obtained after filtration through a 1μm precision filter element. The dynamic friction coefficient of the finished oil is measured to be 0.08 to 0.12 under a load of 500N and a sliding speed of 0.1m / s. In the four-ball machine test, the wear scar diameter is less than 0.35mm and the sintering load is greater than 800N.

[0026] The core of this invention lies in the formation of a composite lubricating film at the die-workpiece interface during the aluminum alloy stretching process. This film, composed of base oil, extreme pressure anti-wear synergist, and photoresponsive self-cleaning additive, is formed by the stretching oil. This film maintains its structural integrity under high temperature and high pressure conditions, effectively isolating direct contact between metal surfaces and inhibiting adhesive wear and scratches. After processing, although the residual organic film on the workpiece surface possesses a certain degree of chemical inertness, the photoresponsive self-cleaning additive embedded within it is activated by ambient visible light (especially the blue-green light components in workshop lighting sources).

[0027] Graphite-phase carbon nitride quantum dots, acting as visible light sensitizers, absorb photon energy to generate electron-hole pairs. Conduction band electrons rapidly migrate to the conduction band of nitrogen-doped titanium dioxide, while valence band holes remain on the quantum dot surface. This charge separation process significantly extends carrier lifetime and enhances redox capabilities. In the presence of oxygen and trace amounts of moisture, photogenerated holes react with water molecules to generate hydroxyl radicals, while photogenerated electrons react with dissolved oxygen to generate superoxide radicals. These two radicals work synergistically to deeply oxidize and degrade neighboring ester and phosphate ester organic molecules, ultimately mineralizing them into water-soluble products such as carbon dioxide, water, and low-molecular-weight carboxylates. This degradation process can achieve over 90% removal of organic residues within 2 hours under standard fluorescent lamp (500 lux) irradiation, without the need for additional chemical cleaning agents.

[0028] The nitrogen-doped titanium dioxide nanocrystals exhibit anatase phase crystallography with a grain size of 8-12 nm and a nitrogen doping concentration of 2.0 at%-4.0 at%. This doping effectively narrows the bandgap of titanium dioxide, red-shifting its absorption edge to 480 nm, thus enabling photoresponse in the visible light region. The graphitic carbon nitride quantum dots form weak chemical bonds with the silanol groups on the surface of the mesoporous silica carrier through π-π stacking, ensuring dispersion stability in the oil phase and preventing detachment or deactivation at high processing temperatures. Furthermore, the mesoporous structure provides ample reaction space for the diffusion and degradation of organic molecules, and the high-density active sites on the inner walls of the pores ensure efficient degradation reactions.

[0029] In another preferred embodiment of the present invention, a bio-based ester oil may be partially introduced into the base oil, with its content being less than 20% of the total base oil. The bio-based ester oil is trimethylolpropane oleate, with an acid value of less than 1.0 mg KOH / g and a saponification value of 180 mg KOH / g to 200 mg KOH / g. The introduction of this component can further improve the biodegradability and lubricity of the oil without significantly affecting its photodegradability, making it suitable for applications with higher environmental protection requirements.

[0030] The high-lubricity, anti-wear stretching oil described in this invention exhibits multiple synergistic effects in practical applications. First, during the stretching and forming stage, tricresyl phosphate and thiophosphate synergists form a phosphorus- and sulfur-containing composite chemical adsorption film on the metal surface, which, together with the physical adsorption film of the base oil, constitutes a multi-layer protective structure, significantly reducing the coefficient of friction and preventing micro-welding. Second, the 1-hydroxyethylbenzotriazole passivator preferentially adsorbs onto the active aluminum atom sites on the aluminum alloy surface, inhibiting the corrosion of the matrix by the oxidation products of the base oil. Third, the polyether-modified siloxane defoamer effectively controls the foam generated by air entrapment during high-speed stamping, maintaining the continuity of the oil film. Finally, the photoresponsive self-cleaning additive is chemically inert in non-light-exposed conditions, does not affect processing stability, and only initiates the self-cleaning process when subsequently exposed to visible light.

[0031] The preparation method provided by this invention ensures precise proportioning and uniform dispersion of each component. The high-speed shear emulsification process is a critical control point, as its rotational speed and time parameters directly affect the dispersion state of the nano-additives. Insufficient shear strength can easily lead to particle agglomeration, reducing photocatalytic efficiency; excessive shearing may damage the mesoporous structure, affecting drug loading capacity. Furthermore, the filtration process uses a 1μm precision filter element, which can effectively remove mechanical impurities and undispersed particles, preventing clogging of the oil supply system or scratching of the workpiece surface.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. By preparing a photoresponsive self-cleaning additive system, the lubrication function and post-treatment compatibility were unified, fundamentally solving the technical contradiction of difficult cleaning of traditional drawing oil residue.

[0034] 2. The degradation process relies solely on ambient visible light, requiring no additional energy input or chemical agents, which aligns with the concept of green manufacturing;

[0035] 3. The degradation products are water-soluble small molecules that can be discharged with conventional water washing processes, significantly reducing the amount of strong acid used and wastewater treatment costs.

[0036] 4. Thorough removal of residues significantly improves the adhesion and uniformity of the anodized film, reducing rework rate;

[0037] 5. The synergistic effect of the components in the formula ensures high lubrication and wear resistance while also taking into account comprehensive properties such as anti-oxidation, rust prevention and defoaming, meeting the needs of continuous industrial production.

[0038] 6. A high-lubricating, anti-wear, and stretching oil with a well-defined structure, reliable performance, and environmentally friendly properties, as well as its preparation method, is provided. This successfully overcomes the inherent contradiction between processing performance and post-processing compatibility in traditional lubrication systems, and provides a brand-new technical path for the integrated process of precision aluminum alloy forming and surface treatment. Detailed Implementation

[0039] This invention provides a high-lubricity, anti-wear drawing oil and its preparation method suitable for metal processing, aiming to solve the technical problem of reduced adhesion of anodized coatings and the need for strong acid cleaning after aluminum alloy drawing due to the residue of traditional drawing oil. This drawing oil, while ensuring excellent boundary lubrication and extreme pressure anti-wear performance, allows its surface residue film to degrade in situ into water-soluble small molecules under visible light irradiation, eliminating the need for strong acid cleaning and significantly improving the efficiency and environmental friendliness of subsequent surface treatments.

[0040] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples, so as to ensure that those skilled in the art can fully understand and implement the present invention.

[0041] Example 1: The base oil is hydrotreated mineral oil (kinematic viscosity 45 mmHg at 40°C). 2 / s) 90.0%; Photoresponsive self-cleaning additive 5.0% (mesoporous silica carrier loaded with 20% nitrogen-doped titanium dioxide + 8% graphitic carbon nitride quantum dots); Extreme pressure anti-wear synergist 3.0% (tricresyl phosphate: thiophosphate = 3:1); Antioxidant stabilizer 0.7% (2,6-di-tert-butyl-p-cresol: alkylated diphenylamine = 1:1); Metal passivator 0.5%; Defoamer 0.3%;

[0042] Preparation process: The base oil is preheated at 60°C, and the additives are added sequentially and stirred at a constant temperature for 30 minutes; high-speed shear emulsification is carried out at 1500 rpm at 80°C for 60 minutes (the feed rate of the light-responsive additive is 0.5 g / min); and then filtered through a 1 μm filter.

[0043] Example 2: 3.0% of light-responsive self-cleaning additive, with the remaining formulation parameters the same as in Example 1;

[0044] Preparation process: Same as in Example 1.

[0045] Example 3: 8.0% of a light-responsive self-cleaning additive, with the remaining formulation parameters the same as in Example 1;

[0046] Preparation process: Same as in Example 1.

[0047] Example 4: The extreme pressure anti-wear synergist contains tricresyl phosphate: thiophosphate in a ratio of 2:1, with other formulation parameters the same as in Example 1;

[0048] Preparation process: Same as in Example 1.

[0049] Example 5: The extreme pressure anti-wear synergist contains 4 parts tricresyl phosphate to 1 part thiophosphate, and the other formulation parameters are the same as in Example 1;

[0050] Preparation process: Same as in Example 1.

[0051] Example 6: The base oil is hydrotreated mineral oil + 15% trimethylolpropane oleate (total 90.0%), and the other formulation parameters are the same as in Example 1;

[0052] Preparation process: Same as in Example 1.

[0053] Example 7: The base oil is a polyalphaolefin synthetic oil (kinematic viscosity 50 mmHg at 40°C). 2 / s) 90.0%, and the remaining formulation parameters are the same as in Example 1;

[0054] Preparation process: Same as in Example 1.

[0055] Example 8: The photoresponsive additive contains 15% nitrogen-doped titanium dioxide and 5% graphitic carbon nitride quantum dots, with the remaining formulation parameters the same as in Example 1;

[0056] Preparation process: Same as in Example 1.

[0057] Comparative Example 1: Base oil 95.0% (same as Example 1); extreme pressure anti-wear synergist 3.0%; antioxidant stabilizer 0.7%; metal passivator 0.5%; defoamer 0.3%; no P-light-responsive self-cleaning additive;

[0058] Preparation process: Same as in Example 1 (without high-speed shear emulsification photoresponsive additive steps).

[0059] Comparative Example 2: The photoresponsive additive was replaced with 5.0% pure nitrogen-doped titanium dioxide (without graphite phase carbon nitride quantum dots), and the other formulation parameters were the same as in Example 1;

[0060] Preparation process: Same as in Example 1.

[0061] Test method:

[0062] Lubrication and anti-wear performance testing: The dynamic friction coefficient (500N load, 0.1m / s sliding speed) was tested using a friction and wear testing machine; the wear scar diameter and sintering load were tested using a four-ball machine; and the surface scratches of the workpiece were observed by simulating a tensile process.

[0063] Self-cleaning performance test: Surface residual degradation rate was measured after 2 hours of visible light irradiation; contact angle change was tested (hydrophilicity characterization); X-ray photoelectron spectroscopy was used to analyze the residual carbon content on the surface.

[0064] Post-treatment and compatibility testing: After anodizing, the coating adhesion was tested using the cross-cut method; the pH value and COD content of the cleaning wastewater were tested; and the antioxidant stability of the stretching oil was evaluated (aged at 100℃ for 72 hours).

[0065] Test data comparison table 1:

[0066] Test Project Dynamic friction coefficient Four-ball mill grinding scar diameter (mm) Residual degradation rate (%) Example 1 0.1 0.32 92 Example 2 0.12 0.35 85 Example 3 0.08 0.3 95 Example 4 0.11 0.34 91 Example 5 0.09 0.31 90 Example 6 0.09 0.3 93 Example 7 0.08 0.29 92 Example 8 0.11 0.33 88 Comparative Example 1 0.13 0.38 15 Comparative Example 2 0.11 0.34 65

[0067] Test data comparison table 2:

[0068] Test Project Anodized coating adhesion (grade) Wastewater COD (mg / L) Example 1 0 85 Example 2 0 92 Example 3 0 80 Example 4 0 88 Example 5 0 86 Example 6 0 82 Example 7 0 78 Example 8 0 90 Comparative Example 1 2 350 Comparative Example 2 1 180

[0069] Examples 1-8, due to the addition of composite photoresponsive additives, have a residual degradation rate of ≥85%, do not require strong acid cleaning, and have wastewater COD ≤92mg / L; Comparative Example 1 has no self-cleaning function, the residue is difficult to degrade, and the coating adhesion is poor, confirming that photoresponsive additives are the key to solving post-treatment problems.

[0070] As shown in Examples 1-3, lubricity and degradation rate increase simultaneously with the increase of light-responsive additive content; as shown in Examples 1, 4, and 5, the extreme pressure synergist ratio is optimized, the wear scar diameter is reduced, and the lubrication and anti-wear performance is enhanced; the introduction of bio-based esters or synthetic oils into the base oil (Examples 6-7) further optimizes the performance and can be adapted to different environmental protection and working conditions.

[0071] Comparative Example 2, using a single photocatalyst, showed a degradation rate of only 65%, lower than the 92% of Example 1, confirming that the synergistic effect of nitrogen-doped titanium dioxide and graphitic carbon nitride quantum dots can enhance photocatalytic efficiency.

[0072] Examples 1-8 all achieve a balance between lubricity and post-treatment compatibility, with a dynamic friction coefficient ≤0.12 and a wear scar diameter ≤0.35mm, while the coating adhesion is grade 0. Although the traditional stretching oil (Comparative Example 1) has basic lubricity, the post-treatment pollution is severe and cannot meet the requirements of green manufacturing.

[0073] The preparation processes in Examples 1-8 are compatible with existing production equipment. After filtration, there is no particle agglomeration, and they can be directly used in processes such as deep drawing of aluminum alloys. They are suitable for processing 5-series, 6-series, and 7-series aluminum alloy sheets.

[0074] The drawing oil described in this invention solves the contradiction between the lubricity of traditional drawing oils and the difficulty of post-treatment cleaning through the synergistic design of photoresponsive self-cleaning additives and extreme pressure anti-wear synergistic formula. Different parameter combinations can meet the requirements of precision metal processing and environmental protection, and are suitable for the production of high-end aluminum alloy products.

[0075] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-lubricating, anti-wear, and stretching oil, characterized in that, It consists of the following components by mass percentage: Base oil 85.0%-92.0%, Light-responsive self-cleaning additives: 3.0%-8.0% Extreme pressure anti-wear synergist 1.0%-4.0%, Antioxidant stabilizer 0.3%-1.0%, Metal passivating agent 0.2%-0.8%, Defoamer 0.1%-0.5%.

2. The high-lubricity, anti-wear, and tensile oil according to claim 1, characterized in that, The base oil is selected from hydrorefined mineral oil, polyalphaolefin synthetic oil, or mixtures thereof.

3. The high-lubricity, anti-wear, and tensile oil according to claim 1, characterized in that, The photoresponsive self-cleaning additive is a composite photocatalyst system supported on a mesoporous silica support. The system contains nitrogen-doped titanium dioxide nanocrystals accounting for 15%-25% of the support mass and graphitic carbon nitride quantum dots accounting for 5%-10% of the support mass.

4. The high-lubricity, anti-wear, and tensile oil according to claim 1, characterized in that, The extreme pressure anti-wear synergist is a compound of tricresyl phosphate and thiophosphate, with a mass ratio of 2:1 to 4:

1.

5. The high-lubricity, anti-wear, and tensile oil according to claim 1, characterized in that, The antioxidant stabilizer is a combination of 2,6-di-tert-butyl-p-cresol and alkylated diphenylamine in a mass ratio of 1:

1.

6. The high-lubricity, anti-wear, and tensile oil according to claim 1, characterized in that, The metal passivating agent is 1-hydroxyethylbenzotriazole.

7. The high-lubricity, anti-wear, and tensile oil according to claim 1, characterized in that, The defoamer is a polyether-modified siloxane.

8. The high-lubricity, anti-wear, and tensile oil according to claim 2, characterized in that, The base oil contains less than 20% of a bio-based ester oil, which is trimethylolpropane oleate.

9. A method for preparing a high-lubricating, anti-wear, and stretching oil as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Preheat the base oil to 60°C, and add the extreme pressure anti-wear synergist, antioxidant stabilizer, metal passivator and defoamer in sequence under stirring, and stir at a constant temperature for 30 minutes. Then, light-responsive self-cleaning additive powder was added, and the mixture was sheared and emulsified at 1500 rpm at 80°C for 60 minutes. Finally, the product is filtered through a 1μm precision filter element to obtain the finished stretching oil.

10. The preparation method according to claim 9, characterized in that, The preparation of the photoresponsive self-cleaning additive includes: S10: Mesoporous silica carrier microspheres were prepared by hydrolysis and condensation of tetraethyl orthosilicate as a precursor at 30°C for 4 hours under the catalysis of ammonia. S20: Disperse the microspheres in water, add a mixture of tetrabutyl titanate and urea, and perform a hydrothermal reaction at 80°C for 12 hours to allow nitrogen-doped titanium dioxide nanocrystals to grow in situ on the inner wall of the pores. S30: The obtained material is immersed in an ethanol dispersion of graphitic carbon nitride quantum dots and dried under vacuum at 60°C for 6 hours to anchor the quantum dots to the outer surface of the carrier.