Antirust oil for zinc-based hot-formed steel and method for preparing the same

Abstract

The application relates to a rust-proof oil for zinc-based hot forming steel and a preparation method, and belongs to the technical field of rust-proof oil.The rust-proof oil comprises, in parts by weight, hydrogen cracking base oil: 80-90 parts, modified nano titanium dioxide: 0.5-1 part, high-temperature self-lubricating agent: 5-10 parts, antioxidant: 0.25-0.5 part, dispersant: 0.5-2 parts, rust-proof agent: 0.5-1 part and functional additive 1-2 parts.The components synergistically act, so that the rust-proof oil can form a dense, stable and self-lubricating protective film on the surface of the zinc-based hot forming steel.The protective film can not only effectively prevent oxidation and volatilization of zinc under high temperature, but also reduce intermetallic friction and optimize the forming process.

Description

Technical Field

[0001] This application relates to the field of metal processing and protective materials, and in particular to a zinc-based rust-preventive oil for hot-formed steel and its preparation method. Background Technology

[0002] With the ongoing global shift towards a cleaner energy structure and the continued pursuit of energy conservation and emission reduction goals, the automotive industry's demand for lightweight vehicle bodies is growing stronger. Hot-formed high-strength steel (HSS), with its high tensile strength after forming and significantly improved body rigidity and collision energy absorption performance, has become the preferred material for critical safety structural components of the vehicle body. However, balancing high strength and corrosion resistance presents new technical challenges in the hot-forming process. Zinc coating of the steel sheet before hot forming can form a dense protective film on the substrate surface, effectively blocking corrosive media under normal and medium-temperature conditions. In actual production, Zn-coated HSS is widely used in load-bearing and energy-absorbing parts of the vehicle body, such as the C-pillar and B-pillar, where its excellent mechanical properties and corrosion resistance ensure the safety and durability of the entire vehicle. However, during the hot-forming stage, the process temperature typically reaches above 900℃. At this temperature, the zinc layer is prone to oxidation, generating insoluble compounds such as zinc oxide (ZnO), leading to surface roughness and localized defects, which in turn affects the quality of subsequent painting, electrophoresis, and bonding. Meanwhile, the volatilization of zinc at high temperatures not only causes material loss but also generates harmful gas emissions, posing a threat to the production environment and operational safety.

[0003] To address the aforementioned issues, traditional processes often rely on shot blasting to remove high-temperature oxides and improve coating adhesion and surface quality. While shot blasting can remove oxide layers to some extent, its limitations are becoming increasingly apparent: firstly, heavy-duty shot blasting equipment requires significant investment and is complex to maintain, making it difficult to meet the high-efficiency production requirements of continuous production lines; secondly, mechanical impact can damage the substrate surface at a microscopic scale, increasing surface roughness and reducing coating adhesion uniformity. Furthermore, the large amounts of dust and noise emitted not only affect the workshop environment but also pose occupational health risks to operators.

[0004] Most rust-preventive oils used in current industrial applications lack sufficient thermal stability and self-lubricating properties, making it difficult to maintain a complete protective layer during hot forming. After the oil film fails at high temperatures, it not only fails to prevent further oxidation of the zinc layer but also leads to insufficient lubrication, increasing mold wear and forming defect rates. Therefore, a novel protective technology integrating high-temperature corrosion prevention, stable lubrication, and shot blasting-free operation is urgently needed for hot-formed high-strength steel during high-temperature hot forming. This technology should be able to form a dense protective film even under extreme conditions above 900℃, effectively inhibiting ZnO formation and zinc volatilization, while providing long-lasting lubrication for hot forming molds, reducing forming resistance and surface damage, thereby simplifying the production process, improving production efficiency, and meeting environmental and safety requirements. Summary of the Invention

[0005] This application provides a rust-preventive oil for zinc-based hot-formed steel and its preparation method to solve the following technical problem: how to solve the problem that zinc-based hot-formed steel is prone to zinc layer oxidation during high-temperature processing in the prior art. In a first aspect, embodiments of this application provide a zinc-based rust-preventive oil for hot-formed steel, wherein the rust-preventive oil is composed of the following components by weight: hydrocracked base oil: 80-90 parts, modified nano titanium dioxide: 0.5-1 part, high-temperature self-lubricating agent: 5-10 parts, antioxidant: 0.25-0.5 parts, dispersant: 0.5-2 parts, rust inhibitor: 0.5-1 part, and functional additives: 1-2 parts.

[0006] Optionally, the hydrocracking base oil is at least one of mineral oil, synthetic oil, and vegetable oil.

[0007] Optionally, the particle size of the modified nano-titanium dioxide is 10 nm to 30 nm.

[0008] Optionally, the high-temperature self-lubricant is at least two of sulfurized fatty acid esters, aminothioesters, di-n-butyl phosphite, and aromatic phosphate esters.

[0009] Optionally, the antioxidant is at least one of phenolic antioxidants and amine antioxidants.

[0010] Optionally, the dispersant is boronized polyisobutylene monosuccinimide, and dehydrated sorbitan fatty acid ester or fatty amine polyoxyethylene ether.

[0011] Optionally, the rust inhibitor is one or more of the following: organic acid corrosion inhibitor, azole corrosion inhibitor, amide corrosion inhibitor, pyridine corrosion inhibitor, and aromatic corrosion inhibitor.

[0012] Optionally, the functional additives include wetting agents and thickeners.

[0013] Secondly, this application provides a method for preparing the zinc-based hot-formed steel rust-preventive oil described in the first aspect, the method comprising: Modified nano-titanium dioxide was obtained by using a silane coupling agent to modify nano-titanium dioxide. The hydrocracking base oil is heated to 50°C to 60°C to obtain preheated hydrocracking base oil; Under continuous stirring, the dispersant and the modified nano-titanium dioxide were added sequentially to the preheated hydrocracking base oil to obtain a mixture; When the temperature of the mixture is 40℃~50℃, the antioxidant, the rust inhibitor, the high-temperature self-lubricating agent and the functional additive are added to the mixture in sequence to obtain a semi-finished rust-preventive oil. The semi-finished rust-preventive oil is stirred for 30 to 60 minutes, and then cooled and filtered sequentially to obtain the finished rust-preventive oil.

[0014] Optionally, the silane coupling agent is one or two of KH550, KH560 and KH570.

[0015] This application provides a zinc-based rust-preventive oil for hot-formed steel, which, by weight, comprises the following components: hydrocracked base oil: 80-90 parts, modified nano-titanium dioxide: 0.5-1 part, high-temperature self-lubricating agent: 5-10 parts, antioxidant: 0.25-0.5 parts, dispersant: 0.5-2 parts, rust inhibitor: 0.5-1 part, and functional additives: 1-2 parts. Hydrocracking base oil can form a uniform and dense oil film on the steel surface, isolating moisture and oxygen and reducing corrosion. Titanium dioxide, after modification with a silane coupling agent, significantly improves its affinity with both the hydrocracking base oil and the steel surface, forming stable chemical bonds. The titanium dioxide particles possess excellent high-temperature resistance, effectively isolating oxygen at high temperatures and protecting the zinc layer from oxidation. The silane coupling agent transforms into silicon dioxide at high temperatures, synergistically forming a double oxide barrier with titanium dioxide, effectively isolating oxygen and inhibiting Zn oxidation and volatilization. High-temperature self-lubricating agents effectively reduce the coefficient of friction between metals at high temperatures, reducing frictional heat generation and preventing corrosion on metal surfaces. Scratches or damage caused by excessive wear; antioxidants effectively neutralize free radicals in the oil, preventing the expansion of oxidation chain reactions, thereby extending the service life of the rust-preventive oil and ensuring its stable performance during storage and use; dispersants ensure the uniform dispersion of solid particles (such as TiO2) in the rust-preventive oil, preventing particle aggregation and sedimentation, and ensuring the uniformity and stability of the coating; the addition of rust inhibitors can form a stable corrosion-inhibiting film on the steel surface, further isolating corrosive factors such as oxygen and moisture, and improving the protective performance of the rust-preventive oil; through the synergistic effect of the above components, the rust-preventive oil can form a dense, stable, and self-lubricating protective film on the surface of zinc-based hot-formed steel. This protective film not only effectively prevents the oxidation and volatilization of zinc at high temperatures, but also reduces friction between metals and optimizes the forming process. Attached Figure Description The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart illustrating a method for preparing a zinc-based hot-formed steel rust-preventive oil according to an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1 to 6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0020] In a first aspect, embodiments of this application provide a zinc-based rust-preventive oil for hot-formed steel, wherein the rust-preventive oil is composed of the following components by weight: hydrocracked base oil: 80-90 parts, modified nano titanium dioxide: 0.5-1 part, high-temperature self-lubricating agent: 5-10 parts, antioxidant: 0.25-0.5 parts, dispersant: 0.5-2 parts, rust inhibitor: 0.5-1 part, and functional additives: 1-2 parts.

[0021] The zinc-based rust-preventive oil for hot-formed steel provided in this application is suitable for the rust-preventive oil coating process in the production stage. In steel production, rust-preventive oil is typically applied using various methods such as spraying, brushing, and dipping to ensure uniform and effective protection of the steel surface. The purpose of applying the rust-preventive oil is to form a dense protective film on the steel surface, preventing the penetration of moisture, oxygen, and other corrosive substances, thereby effectively preventing oxidation or corrosion of the steel during storage, transportation, and processing. Furthermore, this protective film reduces the reaction between the steel surface and oxygen in the air during high-temperature heating or cooling, preventing rust spots or burns on the steel surface and ensuring the smooth progress of subsequent processing steps such as cold rolling and heat treatment. Simultaneously, the rust-preventive oil also reduces the coefficient of friction on the steel surface, reducing damage during processing and further improving production efficiency and product quality. In some embodiments, the thickness of the oil film formed by the zinc-based rust-preventive oil on the steel surface can be 500 mg / m³. 2 ~1000 mg / m 2 The thickness of this oil film varies depending on the different needs of zinc-based hot-formed steel users.

[0022] In the zinc-based hot-formed steel rust-preventive oil, hydrocracking base oil is the main component, playing a core role in providing a basic protective layer for the metal surface. Its main function is to form a uniform and dense oil film on the steel surface, effectively preventing moisture and oxygen from contacting the metal surface, thereby reducing corrosion. Simultaneously, under the high-temperature conditions of heat treatment, the hydrocracking base oil undergoes high-temperature decomposition, consuming a certain amount of oxygen and reducing Zn oxidation to some extent. In the production process of zinc-based hot-formed steel, the selection of hydrocracking base oil requires comprehensive consideration of its viscosity, lubricity, and compatibility with other components. In this embodiment, the hydrocracking base oil has a weight ratio of 80 to 90 parts, ensuring an optimal balance between its lubricity and fluidity, guaranteeing both efficient coating and the formation of a stable and durable protective layer. If the weight ratio of the hydrocracking base oil is less than 80 parts, the rust-preventive effect will be significantly weakened; while a weight ratio greater than 90 parts may result in an excessively thick film, affecting coating uniformity and subsequent processing. Therefore, a hydrocracking base oil with a weight composition of 80 to 90 parts can effectively balance rust prevention, lubrication, and film quality, ensuring that steel is protected from external corrosive factors during hot forming. For example, the weight composition of the hydrocracking base oil can be 80, 82, 84, 86, 88, or 90 parts.

[0023] Titanium dioxide (TiO2), a common inorganic filler, exhibits significantly enhanced affinity with hydrocracking base oils and steel surfaces after modification with silane coupling agents. Through the action of the silane coupling agent, a layer of silane groups forms on the TiO2 surface. These groups can chemically react with film-forming agents in the oil, thereby enhancing the stability and adhesion of the film. TiO2 possesses excellent high-temperature resistance, enabling it to stably isolate oxygen under the high-temperature conditions of heat treatment, protecting the Zn layer from oxidation. Furthermore, the silane coupling agent on the modified nano-titanium dioxide surface further transforms into SiO2 under high-temperature conditions, supplementing the TiO2 film and more effectively isolating oxygen.

[0024] In this embodiment, the modified nano-titanium dioxide is present in an amount of 0.5 to 1 part by weight, ensuring uniform dispersion of the modified nano-titanium dioxide in the oil film and enhancing its anti-corrosion and anti-oxidation effects. The modified nano-titanium dioxide exhibits strong temperature resistance, effectively preventing oxygen and moisture from reacting with the steel surface, thus avoiding surface Zn oxidation. Furthermore, the TiO2 particles improve the wear resistance of the film, resulting in better formability during the processing of zinc-based hot-formed steel. If the modified nano-titanium dioxide content exceeds 1 part by weight, it will affect the compatibility with the rust-preventive oil and its other functions. Therefore, a weight range of 0.5 to 1 part of modified nano-titanium dioxide allows it to fully exert its effectiveness and ensures the uniformity and stability of the film.

[0025] High-temperature self-lubricants effectively reduce friction between metals under high pressure and high temperature conditions, significantly lowering the coefficient of friction and thus reducing frictional heat generation, preventing scratches or damage to metal surfaces due to excessive wear. In the processing of zinc-based hot-formed steel, high-temperature self-lubricants form a stable lubricating film, enhancing the steel's wear resistance and ensuring the metal surface remains smooth under high temperature and pressure conditions, reducing surface damage caused by friction. In this embodiment, the high-temperature self-lubricant is present in an amount of 5-10 parts by weight, ensuring sufficient lubrication from the rust-preventive oil during hot forming, reducing frictional resistance between metals, optimizing the forming process, reducing forming defects caused by excessive frictional resistance, and improving product surface quality and forming accuracy. By reducing friction and wear between the metal and the mold, high-temperature self-lubricants can also effectively extend the mold's service life, reduce mold maintenance costs and replacement frequency, thereby improving overall production efficiency.

[0026] Antioxidants effectively prevent rust-preventive oils from oxidizing due to contact with oxygen in the air during storage and use, thus maintaining their good performance and extending their service life. When rust-preventive oils are exposed to high temperatures or significant environmental changes for extended periods, antioxidants inhibit oxidation reactions in the oil, preventing changes in its composition and ensuring that its lubricity and rust-preventive effects remain unaffected, thus maintaining the oil's stability. In this embodiment, the antioxidant is present in an amount of 0.25–0.5 parts by weight, which prevents the formation of insoluble deposits during storage and use, avoiding contamination of the steel surface or impact on coating uniformity. Finally, by inhibiting oxidation reactions, antioxidants maintain the effectiveness of other active ingredients in the rust-preventive oil, thereby indirectly improving its rust-preventive effect on zinc-based hot-formed steel and ensuring that the steel surface remains uncorroded during long-term storage and transportation.

[0027] Dispersants effectively prevent the precipitation or aggregation of solid particles (such as modified nano-titanium dioxide) in rust-preventive oils, ensuring that these particles remain uniformly dispersed in the oil. Uniform particle dispersion ensures that the rust-preventive oil forms a uniform and dense protective film during coating, avoiding uneven thickness in certain areas and improving coating uniformity and consistency. In this embodiment, the dispersant is used in an amount of 0.5 to 2 parts by weight, preventing solid particles from clogging nozzles or pipes in the spraying equipment, ensuring smooth spraying of the rust-preventive oil onto the steel surface, and improving coating efficiency. Finally, by maintaining the uniform dispersion of solid particles, the dispersant also enhances the stability of the rust-preventive oil film, preventing cracking or peeling during use, thereby improving the protective effect of the rust-preventive oil.

[0028] Rust inhibitors can form a dense protective film on the surface of steel, effectively isolating oxygen, moisture, and other corrosive substances, thereby significantly improving the rust-preventive effect of rust-preventive oil and protecting zinc-based hot-formed steel from corrosion. By forming a stable protective film, rust inhibitors can reduce corrosion loss of steel during storage, transportation, and processing, thereby extending the service life of steel and reducing replacement and maintenance costs. In the embodiments of this application, the rust inhibitor content of 0.5 to 1 part by weight can enhance the adhesion between the rust-preventive oil film and the steel surface, ensuring that the film is not easily peeled off or detached during long-term use and maintains stable rust-preventive performance. Finally, rust inhibitors can also work synergistically with other components (such as hydrocracked base oil, dispersants, etc.) to optimize the overall coating performance of the rust-preventive oil, such as improving the hardness, wear resistance, and weather resistance of the coating, further enhancing the protective effect on steel.

[0029] In some embodiments, the hydrocracked base oil is at least one of mineral oil, synthetic oil, and vegetable oil.

[0030] In some embodiments, the particle size of the modified nano-titanium dioxide is 10 nm to 30 nm.

[0031] Modified nano-titanium dioxide with a particle size of 10nm to 30nm can ensure good compatibility with hydrocracking base oil, making the protective film formed during heat treatment more dense and effectively blocking the intrusion of corrosive substances.

[0032] In some embodiments, the high-temperature self-lubricant is at least two of sulfurized fatty acid esters, aminothioesters, di-n-butyl phosphite, and aromatic phosphate esters.

[0033] Sulfated fatty acid esters effectively reduce friction and wear at high temperatures and enhance extreme pressure performance by forming metal sulfide films; amino thioesters react with the metal surface through amino groups to form stable nitrogen bonds, further improving wear resistance and oxidation resistance; di-n-butyl phosphite and aromatic phosphate esters play a role in high-temperature self-lubrication by forming a phosphate protective film.

[0034] In some embodiments, the antioxidant is at least one of phenolic antioxidants and amine antioxidants.

[0035] Phenolic antioxidants effectively neutralize free radicals in oils through hydrogen transfer reactions, preventing the expansion of oxidation chain reactions. Their reactive hydrogen atoms supply free radicals, converting them into stable phenolic free radicals, thereby terminating the oxidation reaction. Amine antioxidants inhibit oxidation by adsorbing onto metal surfaces and neutralizing oxidation products, enhancing the antioxidant properties of oils. When used in combination, both can work synergistically through multiple mechanisms such as hydrogen transfer and free radical neutralization, providing comprehensive oxidation protection for rust-preventive oils, thus ensuring the stability and excellent performance of the rust-preventive oils during storage and use. In the embodiments of this application, phenolic antioxidants include, but are not limited to, 2,6-di-tert-butyl-p-cresol and 4-methyl-2,6-di-tert-butylphenol. Amine antioxidants include diphenylamine derivatives.

[0036] In some embodiments, the dispersant is boronized polyisobutylene monosuccinimide, and dehydrated sorbitan fatty acid ester or fatty amine polyoxyethylene ether.

[0037] Sorbitol fatty acid esters and fatty amine polyoxyethylene ethers, through their hydrophilic and lipophilic structural properties, can effectively adsorb onto the particle surface, providing stable dispersion force, preventing particle attraction and aggregation, and thus maintaining particle dispersibility. Boronized polyisobutylene monosuccinimide, through the interaction of its polar groups with the particle surface, further enhances the dispersion effect and prevents particle sedimentation. In the embodiments of this application, the dispersant is a compound of boronized polyisobutylene monosuccinimide with one of sorbitol fatty acid esters and fatty amine polyoxyethylene ethers, which not only improves the stability of the rust-preventive oil but also ensures that the coating uniformly and reliably covers the metal surface during application, thereby enhancing rust prevention performance and extending service life.

[0038] In some embodiments, the rust inhibitor is one or more of the following: organic acid corrosion inhibitor, azole corrosion inhibitor, amide corrosion inhibitor, pyridine corrosion inhibitor, and aromatic corrosion inhibitor.

[0039] Organic acids, azoles, amides, pyridines, and aromatic corrosion inhibitors, through their unique molecular structures and chemical activities, can form an effective protective layer on metal surfaces. Specifically, organic acids bind to metal surfaces through their strong hydrophilicity, forming a water-soluble protective layer; azoles and amides bind to metal surfaces, forming a chemisorption layer that enhances corrosion resistance; pyridines exhibit excellent electrochemical stability, improving rust prevention and preventing electrochemical reactions on metal surfaces; and aromatics interact with metal surfaces through their π-electron system, forming an extremely stable protective layer. Different types of rust inhibitors can synergistically enhance their protective effect based on their different mechanisms of action. Using these combinations of rust inhibitors can effectively improve the stability of rust-preventive oils and enhance the corrosion resistance of steel.

[0040] In some embodiments, the functional additives include wetting agents and thickeners.

[0041] In this embodiment, the addition of functional additives is to further optimize the performance of the rust-preventive oil. These functional additives include wetting agents and thickeners. The wetting agent can be 0.3 to 0.7 parts by weight, and the thickener can be 0.2 to 0.5 parts by weight. The wetting agent reduces the interfacial tension between the rust-preventive oil and the metal surface, making it easier for the oil to spread and penetrate, thus forming a uniform and dense protective film. By improving wettability, the wetting agent also enhances the adhesion between the rust-preventive oil film and the metal surface, preventing the oil film from peeling or detaching. Wetting agents include fatty acid esters, etc. The thickener increases the viscosity of the rust-preventive oil, ensuring stable fluidity at different temperatures, thereby ensuring a smooth coating process. By increasing viscosity, the thickener also improves the stability of the rust-preventive oil film, preventing it from cracking or leaking under high temperature or high pressure conditions. Polyethylene wax is a commonly used thickener. In this embodiment, the functional additives may also include foam inhibitors, flow modifiers, corrosion inhibitors, etc. These additives can improve the fluidity, storage stability, and anti-fouling ability of the rust-preventive oil. For example, flow modifiers can improve the flowability of rust-preventive oils at low temperatures; foam inhibitors can prevent unnecessary foaming during coating. Adding 1 to 2 parts by weight of functional additives ensures that these additives improve the workability and shelf life of the rust-preventive oil without affecting its primary protective properties. Adding more than 2 parts by weight of functional additives can lead to oil instability, side effects, and affect film quality; while adding less than 1 part may prevent the functional additives from fully exerting their intended effect. Therefore, 1 to 2 parts by weight of functional additives balances the various functions of the oil, ensuring its optimal performance in use.

[0042] In some embodiments, the rust-preventive oil is suitable for galvanized hot-formed steel, zinc-iron alloy hot-formed steel, and zinc-aluminum-magnesium alloy hot-formed steel.

[0043] In some embodiments, the zinc-based coating in the zinc-based hot-formed steel may contain Si and / or Sr and / or Cr elements.

[0044] Figure 1 This is a schematic flowchart illustrating a method for preparing a zinc-based hot-formed steel rust-preventive oil according to an embodiment of this application.

[0045] Please see Figure 1 Secondly, this application provides a method for preparing the zinc-based hot-formed steel rust-preventive oil described in the first aspect, the method comprising: S1. Modify nano-titanium dioxide using a silane coupling agent to obtain modified nano-titanium dioxide. Modified nano-titanium dioxide can be prepared using nanoscale dispersion techniques (such as ultrasonic treatment or high-shear stirring) to ensure uniform particle distribution and prevent sedimentation. In this embodiment, 10 grams of nano-titanium dioxide was dispersed in an aqueous solution of ethanol (ethanol to water volume ratio of 4:1), followed by the addition of 2 grams of KH550. The mixture was stirred continuously at 60°C for 2 hours, centrifuged and washed, and then dried at 80°C to obtain modified nano-titanium dioxide.

[0046] S2. Heat the hydrocracking base oil to 50°C to 60°C to obtain preheated hydrocracking base oil; S3. Under continuous stirring, the dispersant and the modified nano-titanium dioxide are added sequentially to the preheated hydrocracking base oil to obtain a mixture; After adding the modified nano-titanium dioxide, it can be stirred at high speed of 1200 rpm to 1800 rpm for 45 minutes, or ultrasonically dispersed (frequency 40 kHz, power 300 W) for 30 minutes, until the modified nano-titanium dioxide is completely dispersed.

[0047] S4. When the temperature of the mixture is 40℃~50℃, the antioxidant, the rust inhibitor, the high-temperature self-lubricating agent and the functional additive are added to the mixture in sequence to obtain a semi-finished rust-preventive oil. S5. Stir the semi-finished rust-preventive oil for 30 to 60 minutes, and then cool and filter the stirred semi-finished rust-preventive oil in sequence to obtain the finished rust-preventive oil.

[0048] After stirring, the semi-finished rust-preventive oil is cooled to room temperature and filtered through a filter screen with a pore size of ≤10μm to remove undispersed particles and impurities, thus obtaining a uniform finished rust-preventive oil.

[0049] In some embodiments, the silane coupling agent is one or two of KH550, KH560 and KH570.

[0050] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0051] The weight parts of each component of the zinc-based hot-formed steel rust-preventive oil in Examples 1 to 18 are shown in Table 1.

[0052] Table 1. Weight parts of each component of zinc-based hot-formed steel rust-preventive oil

[0053] The main differences between Examples 1-18 lie in the fine-tuning of the mass fraction of each component and the selection of different components. These differences ensure that different examples can achieve different coating effects, rust prevention properties, and applicability to meet various application requirements.

[0054] The basic properties of the zinc-based hot-formed steel rust-preventive oils in Examples 1-18 were analyzed and tested, and the results are shown in Table 2.

[0055] Table 2 Product Performance of Zinc-Based Hot-Formed Steel Rust-Preventive Oils

[0056] The zinc-based hot-formed steels prepared in Examples 1-18 were coated with rust-preventive oil by spraying. The rust-preventive oil-coated zinc-based hot-formed steels were then subjected to high-temperature heat treatment (900 ℃) for 5 minutes. After removal, they were immediately placed in a forging plate mold equipped with a water-cooling device for cooling at a rate of 100 ℃ / s. The phosphating performance, coating performance, and corrosion resistance after coating of the cooled zinc-based hot-formed steel were tested. Good phosphating performance, coating performance, and corrosion resistance after coating indicate that the treated zinc-based hot-formed steel can achieve good phosphating and coating without shot blasting, thus achieving the goal of shot blasting-free treatment. The test parameters for phosphating performance, coating performance, and corrosion resistance after coating are as follows: Phosphating performance test: The treated zinc-based hot-formed steel sheets were cleaned and degreased with PACKA FC-E2011 degreasing agent at 40–50 °C for 2–5 minutes, followed by rinsing with deionized water. The sheets were then transferred to a surface conditioning tank containing PACKA PL-X and surface-conditioned at 25–30 °C for 30 seconds. Finally, the sheets were transferred to a phosphating tank containing PACKA 3065 phosphating solution and phosphated at 40–45 °C for 90 seconds. The phosphating performance evaluation criteria are as follows: Advantages: The phosphating crystals are uniform and smaller than 7 μm, and the phosphating coverage reaches 100%.

[0057] Good: Phosphate crystals are relatively uniform and smaller than 7 μm, with a phosphating coverage of 75%.

[0058] In the middle section: the phosphating crystals are uneven, and the phosphating coverage reaches 50%.

[0059] Poor: No zinc phosphate crystals were precipitated.

[0060] Coating performance test: Electrophoresis was performed on the surface of the phosphated zinc-based hot-formed steel, followed by curing to obtain a zinc-based hot-formed steel electrophoretic plate. The coated sample was tested for paint film performance according to ISO 2409 standard, and the evaluation and grading were carried out according to ISO 2409 standard.

[0061] Grade 0 (Excellent): The cut edges are very smooth, and none of the blocks in the grid are peeled off.

[0062] Grade 1 (Good): On the inner surface of the cut, the small thin layers of coating peel off. There is obvious peeling damage of no more than 5% in the cross-cut area.

[0063] Grade 2 (Good): The coating peels off along the edges and / or on the inner surface of the cut. More than 5% but no more than 15% of the cross-cut area is significantly damaged.

[0064] Level 3 (Medium): The coating peels off in large strips along all or part of the edges of each cut, and / or in all or part of different parts of this square. The cross-cut area shows peeling damage exceeding 15% but not exceeding 35%.

[0065] Grade 4 (Poor): The coating peels off in large strips along the edges of each cut, and / or there are some small squares of partial or complete peeling. The cross-cut area shows significant peeling of more than 35%, but significantly less than 65%.

[0066] Grade 5 (Poor): Not even the thin skin that can be graded as Grade 4.

[0067] Corrosion resistance test after coating: The corrosion resistance of the coated samples was evaluated according to the Japanese JASOM 610 standard. A line was drawn on the paint film of the sample using a cutting tool, and a test was performed for 180 cycles (60 days). After the test, the maximum width of the steam drum on one side from the drawn line was measured. The evaluation criteria for corrosion resistance after coating are as follows: Advantages: Foam width ≤ 3 mm Good: Foaming width 3-6 mm Medium: Foaming width 6-10 mm Poor: Bubble width > 10 mm Table 3 lists the performance test results of the zinc-based hot-formed steel after being coated with rust-preventive oil in Examples 1-18 and the comparative examples 1-5 without rust-preventive oil coating.

[0068] Table 3. Test results of sheet material performance

[0069] As can be seen from the data in Table 1-2, the weight parts of each component of the zinc-based hot-formed steel rust-preventive oil in the embodiments are all within the required range of this application, the theoretical performance meets the standard requirements, and all have good stability and a shelf life of more than 180 days.

[0070] As can be seen from the data in Table 3, the zinc-based hot-formed steel treated with the rust-preventive oil provided in this application has good phosphating performance, coating performance and corrosion resistance after coating without shot blasting. This rust-preventive oil for shot blasting-free production achieves shot blasting-free zinc-based hot-formed steel.

[0071] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: Excellent corrosion resistance: The rust-preventive oil provided in this embodiment of the invention forms a durable and efficient protective film on the surface of zinc-based hot-formed steel, which significantly improves the corrosion resistance of the material, effectively prevents the oxidation and volatilization of the zinc layer under high temperature environment, and significantly extends the service life of the steel.

[0072] Innovative shot blasting-free treatment: Compared with traditional shot blasting processes, the rust-preventive oil provided in this invention can effectively prevent damage to the steel surface and increase roughness, and eliminate dust and noise pollution generated during shot blasting, thereby achieving a cleaner and more environmentally friendly production process.

[0073] High-temperature self-lubricating properties: The rust-preventive oil provided in this embodiment of the invention provides excellent lubrication performance in the thermoforming process by adding a high-temperature self-lubricant, effectively reducing friction between metals, optimizing the forming process, significantly improving the surface quality and processing efficiency of the product, and meeting the requirements of high-temperature processing.

[0074] Simplified process and economic benefits: The use of simple and efficient coating methods such as spraying, brushing or dipping avoids the cumbersome traditional processing techniques. This not only ensures a uniform and stable coating, but also significantly reduces production costs and improves overall production efficiency, making it a promising candidate for industrial applications.

[0075] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A zinc-based rust-preventive oil for hot-formed steel, comprising, by weight, the following components: hydrocracked base oil: 80-90 parts, modified nano-titanium dioxide: 0.5-1 parts, high-temperature self-lubricating agent: 5-10 parts, antioxidant: 0.25-0.5 parts, dispersant: 0.5-2 parts, rust inhibitor: 0.5-1 parts, and functional additives: 1-2 parts.

2. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The hydrocracking base oil is at least one of mineral oil, synthetic oil, and vegetable oil.

3. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The modified nano-titanium dioxide has a particle size of 10 nm to 30 nm.

4. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The high-temperature self-lubricating agent is at least two of the following: sulfurized fatty acid esters, aminothioesters, di-n-butyl phosphite, and aromatic phosphate esters.

5. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The antioxidant is at least one of phenolic antioxidants and amine antioxidants.

6. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The dispersant is boronized polyisobutylene monosuccinimide, and dehydrated sorbitan fatty acid ester or fatty amine polyoxyethylene ether.

7. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The rust inhibitor is one or more of the following: organic acid corrosion inhibitor, azole corrosion inhibitor, amide corrosion inhibitor, pyridine corrosion inhibitor, and aromatic corrosion inhibitor.

8. The zinc-based rust-preventive oil for hot-formed steel according to claim 1, characterized in that, The functional additives include wetting agents and thickeners.

9. A method for preparing a zinc-based rust-preventive oil for hot-formed steel according to any one of claims 1 to 8, the method comprising: Modified nano-titanium dioxide was obtained by using a silane coupling agent to modify nano-titanium dioxide. The hydrocracking base oil is heated to 50°C to 60°C to obtain preheated hydrocracking base oil; Under continuous stirring, the dispersant and the modified nano-titanium dioxide were added sequentially to the preheated hydrocracking base oil to obtain a mixture; When the temperature of the mixture is 40℃~50℃, the antioxidant, the rust inhibitor, the high-temperature self-lubricating agent and the functional additive are added to the mixture in sequence to obtain a semi-finished rust-preventive oil. The semi-finished rust-preventive oil is stirred for 30 to 60 minutes, and then cooled and filtered sequentially to obtain the finished rust-preventive oil.

10. The method according to claim 9, characterized in that, The silane coupling agent is one or two of KH550, KH560 and KH570.

Images