High-temperature lubricant for vacuum isothermal forging process as well as preparation method and application of high-temperature lubricant

Abstract

The invention provides a high-temperature lubricant for a vacuum isothermal forging process as well as a preparation method and application of the high-temperature lubricant. The lubricant is prepared from the following raw materials: 25 to 35 weight percent of surface activated boron nitride powder, 5 to 8 weight percent of molybdenum disulfide microsphere powder, 8 to 10 weight percent of glass powder, 5 weight percent of potassium silicate, 1 to 2 weight percent of silica gel, 10 to 16 weight percent of feldspar powder, 1.5 to 4 weight percent of flatting agent, 1 to 1.5 weight percent of preservative, 0.8 to 2 weight percent of dispersing agent, 1 to 1.5 weight percent of defoaming agent and the balance of water. The high-performance high-temperature lubricant specially used for the vacuum isothermal forging process is developed by adopting an alkali solution, urea and a silane coupling agent to carry out rapid surface chemical activation treatment and a ball-milling modification technology on boron nitride powder, and has excellent dispersity, lubricity and stability; and the technical defects of the existing glass-based lubricating material are fundamentally overcome.

Description

Technical Field

[0001] This invention belongs to the field of metal hot forming technology, specifically relating to a high-temperature lubricant for vacuum isothermal forging process, its preparation method, and its application. Background Technology

[0002] Vacuum isothermal forging, as an advanced metal forming technology, plays a crucial role in high-performance engineering fields such as aerospace and automotive. This technology, through precise forging under extremely low oxygen content and high temperature conditions, effectively avoids metal oxidation, reduces defects during deformation, and significantly improves the uniformity of the alloy's microstructure and overall performance, making it particularly suitable for the precision machining of high-performance alloys.

[0003] In vacuum isothermal forging, the selection and performance of lubricating materials directly determine the forging quality and die life. High-quality lubricating materials can not only reduce the frictional resistance between the die and the forging, and lower the material deformation resistance, but also effectively disperse the heat generated during forging, making the metal flow more stable, ensuring the uniformity of the forging surface quality, and significantly reducing die wear and extending die life.

[0004] However, while glass-based lubricants widely used in vacuum isothermal forging possess certain lubrication properties, they have revealed several problems in practical applications. Glass-based lubricants exhibit significant corrosiveness to the molds. Prolonged use at high and low temperatures leads to chemical thermal corrosion of the mold surface, resulting in defects such as spalling and corrosion pits. This not only affects the surface quality of the forgings but also significantly shortens the mold's lifespan and increases production costs. Furthermore, the B2O3, Cr2O3, and ZnO components in glass-based lubricants produce volatile substances under high-temperature vacuum conditions. These volatiles corrode and even cause short circuits in precision electronic components such as resistance wires and sensors in vacuum isothermal forging equipment, threatening the stable operation and lifespan of the equipment. More critically, existing lubricants exhibit poor lubrication stability under extreme vacuum, high temperature, and high pressure conditions, making it difficult to consistently provide stable and reliable lubrication.

[0005] Boron nitride, as an excellent solid lubricant, possesses good high-temperature stability and chemical inertness, theoretically making it an ideal choice for vacuum isothermal forging lubrication. Compared to organic solvent-based lubricants, water-based lubricants offer advantages such as environmental friendliness. However, boron nitride exhibits poor dispersibility in water-based systems, leading to uneven lubrication, insufficient compatibility with the metal substrate, and difficulty in forming a well-adhered lubricating coating, thus hindering the full realization of lubrication effects. Therefore, improving the lubrication performance and application effect of boron nitride through surface modification technology, and developing a novel environmentally friendly water-based lubricant that possesses excellent lubrication properties, avoids mold corrosion, and remains stable under vacuum and high-temperature environments, has become a key requirement for the advancement of vacuum isothermal forging technology. Summary of the Invention

[0006] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a high-temperature lubricant for vacuum isothermal forging processes, its preparation method, and its application. Boron nitride powder is rapidly surface-chemically activated using an alkaline solution, urea, and a silane coupling agent. A ball milling process is then used to generate functional groups such as hydroxyl groups on the surface of the boron nitride, thereby altering its hydrophilicity. Next, the surface-activated boron nitride powder, molybdenum disulfide microspheres, glass powder, potassium silicate, silica gel, feldspar powder, leveling agent, preservative, dispersant, defoamer, and water are mixed in a specific ratio to ensure uniform dispersion of each component. The mixed material is then further uniformly dispersed and refined using a grinding device.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a high-temperature lubricant for vacuum isothermal forging process, which is made from the following raw materials: 25-35 wt.% surface-activated boron nitride powder, 5-8 wt.% molybdenum disulfide microsphere powder, 8-10 wt.% glass powder, 5 wt.% potassium silicate, 1-2 wt.% silica gel, 10-16 wt.% feldspar powder, 1.5-4 wt.% leveling agent, 1-1.5 wt.% corrosion inhibitor, 0.8-2 wt.% dispersant, 1-1.5 wt.% defoamer, and the balance being water.

[0008] Preferably, the method for preparing the surface-activated boron nitride powder is as follows: Boron nitride powder is mixed with an alkaline solution, urea, and a silane coupling agent. The mixture is then placed in a ball mill for mechanochemical activation treatment. Stainless steel balls are used as the milling medium, with a ball-to-material ratio of (20-60):1. The ball mill speed is 300-500 rpm, and the milling time is 6-18 h to obtain surface-activated boron nitride powder. The particle size of the boron nitride powder is 0.5-20 μm, and the purity is 99.5%. The alkaline solution is a 20 wt.% NaOH solution. The silane coupling agent is KH550 amino-type silane coupling agent with a purity of 98%. The mass ratio of boron nitride powder, alkaline solution, urea, and silane coupling agent is 100:(20-60):(5-30):(10-25). The diameter of the stainless steel balls is 5-10 mm.

[0009] Preferably, the preparation method of the molybdenum disulfide microsphere powder is as follows: ammonium molybdate and sulfur are mixed at a molar ratio of 1:2, heated to 300-500℃, and reacted in an inert atmosphere to generate molybdenum disulfide; after the reaction is completed, the product is cooled to room temperature and washed with deionized water or alcohol solvent to remove unreacted raw materials or by-products; the washed molybdenum disulfide powder is dried at 60-100℃, ball-milled, and sieved to control the particle size at 5-10 μm to obtain molybdenum disulfide microsphere powder.

[0010] Preferably, the preparation method of the glass powder is as follows: First, the raw materials are mixed according to the following ratio: SiO2 55-75%, Na2O 8-10%, Al2O3 5-10%, CaO 8-10%, MgO 3-5%, ZrO2 0.5-1%, NiO 0.3-2%. The mixed raw materials are then fed into a high-temperature furnace and melted at a temperature of 1350-1450℃ to generate molten glass liquid. Subsequently, the molten glass liquid is cooled into solid glass blocks by rapid cooling or natural cooling. The cooled glass blocks are then crushed and ground into fine powder. After sieving, the particle size is controlled to be 5-10 μm to obtain glass powder.

[0011] Preferably, the feldspar powder is composed of 40-50% sodium feldspar (NaAlSi3O8), 40-50% potassium feldspar (KAlSi3O8), and 10-20% aluminosilicate (Al2SiO8). The leveling agent is composed of 30-50% acrylic resin, 20-40% polyvinyl alcohol, and 10-30% polyether polyol; The preservative is composed of 30-50% benzotriazole, 20-40% thiols and 10-30% organomolybdenum compounds; The dispersant is composed of 40-60% polyacrylic acid, 20-40% polyvinyl alcohol, and 10-20% silane compounds; The defoamer is composed of 40-60% silicone oil, 20-40% fatty acid esters, and 10-20% polyether compounds.

[0012] The present invention also provides a method for preparing the high-temperature lubricant for vacuum isothermal forging process, the method comprising: firstly, dispersing potassium silicate in water and stirring for 30 min at a speed of 400 rpm, adding silica gel and continuing stirring for 60-240 min, then sequentially adding surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder and dispersant, ball milling in a ball mill for 6 h at a speed of 400 rpm, then adding leveling agent, corrosion inhibitor and defoamer to the ball-milled material and continuing ball milling for 2 h, finally obtaining the high-temperature lubricant for vacuum isothermal forging process.

[0013] The present invention also provides the application of the high-temperature lubricant in the vacuum isothermal forging process.

[0014] Compared with the prior art, the present invention has the following significant technical effects: This invention develops a high-performance high-temperature lubricant specifically for vacuum isothermal forging processes using surface activation and boron nitride modification techniques. It exhibits excellent dispersibility, lubricity, and stability, fundamentally overcoming the technical shortcomings of existing glass-based lubricating materials. Details are as follows: (1) Excellent lubrication effect: After surface activation treatment, boron nitride forms a stable lubricating film at the friction interface. The functional groups such as silicon and oxygen grafted on the surface of boron nitride can capture the boron oxide volatilized at high temperature and form a borosilicate glass phase, achieving an ultra-low coefficient of friction. The introduction of surface functional groups greatly enhances the compatibility of boron nitride with water-based solvents and its incompatibility with molds. The lubricant can form a uniform and stable dispersion in the water-based system, significantly reducing frictional resistance and making the metal flow more stable.

[0015] (2) Less adhesion to mold: Excellent high-temperature lubrication and compatibility avoid the problem of physical adhesion of lubricating material to mold material. The lubricating film layer forms a good interface lubrication with the mold surface, and the mold surface basically does not produce adhesion, ensuring smooth demolding of forgings and ensuring the uniformity of forging surface quality.

[0016] (3) Basically no corrosion to the mold: The lubricating material of the present invention uses chemically inert boron nitride as the main lubricating component, which completely avoids chemical corrosion of the mold material, solves the corrosion problem of traditional glass-based lubricating materials, significantly extends the service life of the mold, and reduces the cost of mold replacement and maintenance.

[0017] (4) No volatile substances: The lubricating material exhibits excellent stability in a vacuum high-temperature environment and does not produce volatile substances. This reduces the potential harm of lubricant volatilization to precision electronic components such as resistance wires and sensors in vacuum isothermal forging equipment, significantly improves the safety and stability of equipment operation, and avoids equipment failures and maintenance problems caused by lubrication side effects.

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is the infrared spectrum of boron nitride without treatment in Example 1 of the present invention; Figure 2 This is the infrared spectrum of boron nitride after surface activation modification in Example 1 of this invention; Figure 3 These are photos of the coagulation of surface-activated modified boron nitride and pure boron nitride solution in Example 1 of this invention; Figure 4 This is the friction coefficient curve of the high-temperature lubricant in Example 1; Figure 5 This is a diagram of the dual surface morphology in Example 1; Figure 6 This is the friction coefficient curve of the high-temperature lubricant in Example 2; Figure 7 This is a diagram of the dual surface morphology in Example 2; Figure 8 This is the friction coefficient curve of the high-temperature lubricant in Example 3; Figure 9 This is a diagram of the dual surface morphology in Example 3; Figure 10 This is the friction coefficient curve of the high-temperature lubricant in Example 4; Figure 11 This is a dual surface morphology diagram from Example 4; Figure 12 This is the friction coefficient curve of the high-temperature lubricant in Example 5; Figure 13 This is a diagram of the dual surface morphology in Example 5; Figure 14 The friction coefficient curve of the high-temperature lubricant in Comparative Example 1 is shown. Figure 15 This is a diagram of the dual surface morphology in Comparative Example 1. Detailed Implementation

[0020] This invention provides a high-temperature lubricant for vacuum isothermal forging processes, which is made from the following raw materials: 25-35 wt.% surface-activated boron nitride powder, 5-8 wt.% molybdenum disulfide microsphere powder, 8-10 wt.% glass powder, 5 wt.% potassium silicate, 1-2 wt.% silica gel, 10-16 wt.% feldspar powder, 1.5-4 wt.% leveling agent, 1-1.5 wt.% corrosion inhibitor, 0.8-2 wt.% dispersant, 1-1.5 wt.% defoamer, and the balance being water.

[0021] The boron nitride used in this invention has a particle size of 0.5-20 μm, preferably 3-5 μm, and a purity of 99.5%. The surface activation treatment process of boron nitride includes: mixing boron nitride powder with an alkaline solution (20 wt.% NaOH solution), urea, and a silane coupling agent (KH550) in a certain proportion, specifically, the proportion of boron nitride powder:alkaline solution:urea:silane coupling agent = 100:(20-60):(5-30):(10-25). First, boron nitride powder is mixed with an alkaline solution to provide an alkaline environment, promoting the formation of hydrophilic functional groups such as hydroxyl (-OH) on the surface of boron nitride. Next, urea is added to further react with the boron nitride surface, generating functional groups such as amino (-NH2), thereby enhancing the surface activity of boron nitride. Then, a silane coupling agent is added to enhance the bonding force between boron nitride and other organic matrices, ensuring its compatibility with lubricating materials. Finally, the mixture is placed in a ball mill for mechanochemical activation treatment. The ball mill speed is set to 300-500 rpm, the milling time is 6-18 h, and stainless steel balls (5-10 mm in diameter) are used as the milling medium, with a ball-to-material ratio of (20-60):1. Through the combination of mechanical force and chemical reaction, functional groups such as hydroxyl (-OH), amino (-NH2), and silicon oxide (Si-O-) are generated on the surface of boron nitride, resulting in surface-activated boron nitride powder. This not only significantly improves the surface activity of boron nitride, but also enhances its dispersion performance in water-based systems. The activated boron nitride powder has an optimized surface structure, which enhances its lubricity and compatibility with other components.

[0022] The preparation of molybdenum disulfide microspheres uses ammonium molybdate as the molybdenum source and sulfur as the sulfur source. The method is as follows: the molybdenum source and sulfur source are mixed at a molar ratio of 1:2 and heated to 300-500℃. The reaction is carried out in an inert atmosphere (such as nitrogen or argon) to generate molybdenum disulfide (MoS2). After the reaction is complete, the product is cooled to room temperature and washed with deionized water or an alcohol solvent to remove unreacted raw materials or byproducts (such as Na2SO4). The washed molybdenum disulfide powder is dried at a low temperature of 60-100℃ to remove residual moisture. After ball milling, it is classified using a sieving device to remove larger particles and ensure particle size uniformity. The sieving standard is 5-10 μm, yielding molybdenum disulfide microspheres. The molybdenum disulfide powder prepared in this way exhibits high-temperature stability, chemical inertness, and a low coefficient of friction, making it suitable for use in lubricating materials, especially in applications under high-temperature and high-pressure environments, providing excellent lubrication performance.

[0023] The preparation method of glass powder includes the following steps: First, silica (SiO2), limestone (CaCO3), bauxite (Al2O3), and sodium hydroxide (Na2CO3) are mixed in a certain proportion, specifically: SiO2 55-75%, Na2O 8-10%, Al2O3 5-10%, CaO 8-10%, MgO 3-5%, ZrO2 0.5-1%, and NiO 0.3-2%. The mixed raw materials are then melted in a high-temperature furnace at a temperature controlled at 1350-1450 ℃. The raw materials undergo a chemical reaction at high temperature to generate molten glass. Subsequently, the molten glass is rapidly cooled into solid glass blocks by quenching or natural cooling. The cooled glass blocks are then crushed and ground into fine powder with a particle size controlled at 5-10 μm. The ground glass powder is then sieved to remove unqualified coarse particles, ensuring uniform particle size. These components give glass powder excellent thermal stability, wear resistance, and chemical stability, thus enhancing the stability and wear resistance of the lubricating film, making it suitable for use in lubricating materials.

[0024] Feldspar powder is composed of sodium feldspar (NaAlSi3O8 40-50%), potassium feldspar (KAlSi3O8 40-50%), and aluminosilicate (Al2SiO8 10-20%). It serves as a carrier and reinforcing agent to improve the thermal stability and anti-wear properties of the lubricant.

[0025] The leveling agent is composed of acrylic resin (30-50%), polyvinyl alcohol (20-40%) and polyether polyol (10-30%), and is used to improve the coating performance of the lubricant and ensure the uniformity and smoothness of the coating.

[0026] The corrosion inhibitor is composed of benzotriazole (30-50%), thiol compounds (20-40%), and organomolybdenum compounds (10-30%), which effectively prevents the oxidation of lubricant and the corrosion of mold.

[0027] The dispersant is composed of polyacrylic acid (40-60%), polyvinyl alcohol (20-40%) and silane compounds (10-20%), and is used to ensure uniform dispersion of the components in the lubricant and prevent precipitation or agglomeration.

[0028] The defoamer is composed of silicone oil (40-60%), fatty acid esters (20-40%), and polyether compounds (10-20%). It can effectively remove air bubbles from the lubricant and ensure the stability of the lubrication effect.

[0029] The preparation method of high-temperature lubricant is as follows: Surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, potassium silicate, silica gel, feldspar powder, leveling agent, preservative, dispersant, defoamer, and water are mixed in a specific ratio to ensure uniform dispersion of each component. The mixed material is then further dispersed and refined using grinding equipment. If it is necessary to adjust the fluidity of the lubricant, appropriate solvents or regulators can be added to ensure good coating performance and smoothness. After mixing and grinding, sampling and drying are performed to remove excess solvent or moisture. Finally, after quality inspection, lubricant materials that meet the standards are packaged and stored to ensure product stability. The lubricant obtained in this process has excellent dispersibility, lubricity, and stability, and is suitable for vacuum isothermal forging processes.

[0030] The following detailed description is provided in conjunction with specific embodiments.

[0031] Example 1 This embodiment is a high-temperature lubricant for vacuum isothermal forging process, which is made of the following components: surface-activated boron nitride powder (35 wt.%), molybdenum disulfide microsphere powder (5 wt.%), glass powder (8 wt.%), potassium silicate (5 wt.%), silica gel (2 wt.%), feldspar powder (10 wt.%), leveling agent (2 wt.%), corrosion inhibitor (1 wt.%), dispersant (1.5 wt.%), defoamer (1 wt.%), and the balance being water.

[0032] The preparation method of surface-activated boron nitride powder is as follows: boron nitride powder is mixed with 20 wt.% NaOH solution, urea, and silane coupling agent (KH550 amino-type silane coupling agent (3-aminopropyltriethoxysilane, purity 98%) in a mass ratio of 100:40:20:15. The mixture is placed in a ball mill for mechanochemical activation treatment. Stainless steel balls with a diameter of 7 mm are used as the ball milling medium, the ball-to-material ratio is 40:1, the ball mill speed is 400 rpm, and the ball milling time is 12 h to obtain surface-activated boron nitride powder.

[0033] The infrared spectrum of pure boron nitride is as follows: Figure 1 As shown, two significant absorption peaks are mainly observed, the first of which appears at approximately 812 cm⁻¹. -1 Corresponding to the interlayer bending vibration of boron nitride, another strong peak appears at 1344 cm⁻¹. -1 , representing the in-plane stretching vibration of boron nitride. The spectrum also shows 1413 cm⁻¹. -1 The nearby absorption peaks indicate some changes in the in-plane structure of the material. Overall, the spectral characteristics of boron nitride are consistent with its layered structure and physical properties.

[0034] The infrared spectrum of the surface-activated modified boron nitride prepared in this embodiment is shown below. Figure 2 As shown. 3412 cm -1 The nearby peaks represent moisture, indicating that the sample contains a certain amount of water; the two characteristic peaks of urea appear at 1670 cm⁻¹. -1 and 1618cm -1 This indicates that the urea molecules maintained their original structure during ball milling; simultaneously, the hydrolysis and condensation reactions of the silane coupling agent occurred at 1132 cm⁻¹. -1 and 995 cm -1 This is reflected in the absorption peak of ; the absorption peak of carbonate appears at 1400 cm⁻¹. -1 This indicates that NaOH reacted with carbon dioxide in the air to form carbonates. Overall, infrared spectroscopy reflects the interactions and chemical changes among the components in the sample.

[0035] Figure 3 These are agglomeration photographs of surface-activated modified boron nitride and pure boron nitride solution in this embodiment. As can be seen, the modified sample did not show the stratification seen in the unmodified sample, indicating that its dispersion stability is improved.

[0036] The preparation method of molybdenum disulfide microspheres is as follows: ammonium molybdate and sulfur are mixed at a molar ratio of 1:2 and heated to 400℃. The reaction is carried out in a nitrogen atmosphere to generate molybdenum disulfide. After the reaction is completed, the product is cooled to room temperature and washed with deionized water. The washed molybdenum disulfide powder is dried at 80℃, ball-milled and sieved to control the particle size at 5-10 μm to obtain molybdenum disulfide microspheres.

[0037] The glass powder is made of 67% SiO2, 9% Na2O, 38% Al2O, 9% CaO, 4.5% MgO, 1% ZrO2, and 1.5% NiO; the feldspar powder is composed of sodium feldspar (NaAlSi3O8 45%), potassium feldspar (KAlSi3O8 45%), and aluminosilicate (Al2SiO8 10%); the leveling agent is composed of acrylic resin (40%), polyvinyl alcohol (30%), and polyether polyol (30%); the preservative is composed of benzotriazole (40%), thiol compounds (30%), and organomolybdenum compounds (30%); the dispersant is composed of polyacrylic acid (50%), polyvinyl alcohol (30%), and silane compounds (20%); and the defoamer is composed of silicone oil (50%), fatty acid esters (30%), and polyether compounds (20%).

[0038] The preparation method of high-temperature lubricant includes the following steps: First, potassium silicate is dispersed in water and magnetically stirred for 30 minutes at a speed of 400 rpm. Silica gel is added and stirring is continued for 240 minutes. Then, surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder, and dispersant are added sequentially. The mixture is ball-milled for 6 hours at a speed of 400 rpm. After ball milling, leveling agent, corrosion inhibitor, and defoamer are added to the material and ball milling continues for 2 hours. Finally, a high-temperature lubricant for vacuum isothermal forging process is obtained.

[0039] A lubricating coating was prepared using the lubricant obtained in Example 1, and its lubrication performance was tested. The method was as follows: the sample to be tested, FGH4169, was heated to 100°C in a protective atmosphere furnace. o At temperature C, after holding at this temperature for 1 hour, the prepared lubricant was applied to the surface of the blank by air spraying. Natural cooling was then performed to obtain a tightly bonded lubricant coating with a thickness of approximately 20 μm. The high-temperature tribological properties of the lubricant coating were then evaluated using an HT-1200 high-temperature friction testing machine. The mating pins were N3 alloy, the protective atmosphere was nitrogen (flow rate 5 L / min), the load was 10 N, the frequency was 3 Hz, the running time was 20 min, and the experimental temperature was 1070℃. The results showed that the average coefficient of friction of the lubricant was approximately 0.15, and the coefficient of friction curve is shown below. Figure 4 As shown; the dual surface morphology diagram is as follows. Figure 5As shown, the dual surface is dominated by fine, shallow, and nearly parallel grinding marks and large polished areas, with very few deep grooves / peeling, indicating that a relatively dense and continuous transfer / oxide film was formed under the action of high-temperature lubricant.

[0040] Example 2 This embodiment is a high-temperature lubricant for vacuum isothermal forging process, which is made of the following components: surface-activated boron nitride powder (32 wt.%), molybdenum disulfide microsphere powder (6 wt.%), glass powder (9 wt.%), potassium silicate (5 wt.%), silica gel (2 wt.%), feldspar powder (11 wt.%), leveling agent (1.5 wt.%), corrosion inhibitor (1.5 wt.%), dispersant (1 wt.%), defoamer (1.5 wt.%), and the balance being water.

[0041] The surface-activated boron nitride powder was prepared by mixing boron nitride powder with 20 wt.% NaOH solution, urea, and silane coupling agent (KH550 amino-type silane coupling agent (3-aminopropyltriethoxysilane, purity 98%)) in a mass ratio of 100:20:30:20. The glass powder consisted of 70% SiO2, 8.5% Na2O, 6.6% Al2O3, 9.5% CaO, and MgO. It is made of 3.5% ZrO2, 0.7% NiO, and 1.2% Feldspar powder is composed of sodium feldspar (NaAlSi3O8 42%), potassium feldspar (KAlSi3O8 46%), and aluminosilicate (Al2SiO8 12%); leveling agent is composed of acrylic resin (35%), polyvinyl alcohol (35%), and polyether polyol (30%); preservative is composed of benzotriazole (35%), thiol compounds (35%), and organomolybdenum compounds (30%); dispersant is composed of polyacrylic acid (40%), polyvinyl alcohol (40%), and silane compounds (20%); defoamer is composed of silicone oil (60%), fatty acid esters (20%), and polyether compounds (20%).

[0042] The preparation method of high-temperature lubricant includes the following steps: First, potassium silicate is dispersed in water and stirred magnetically for 30 min at a speed of 400 rpm. Silica gel is added and stirring is continued for 60 min. Then, surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder, and dispersant are added sequentially. The mixture is ball-milled in a ball mill for 6 h at a speed of 400 rpm. After ball milling, leveling agent, corrosion inhibitor, and defoamer are added to the material and ball milling continues for 2 h. Finally, a high-temperature lubricant for vacuum isothermal forging process is obtained.

[0043] A lubricating coating was prepared using the lubricant obtained in Example 2, and its lubrication performance was tested. The method was as follows: the sample to be tested, FGH4169, was heated to 90°C in a protective atmosphere furnace. oAt temperature C, after holding at this temperature for 1 hour, the prepared lubricant was applied to the surface of the blank by air spraying. Natural cooling was then performed to obtain a tightly bonded lubricant coating with a thickness of approximately 20 μm. The high-temperature tribological properties of the lubricant coating were then evaluated using an HT-1200 high-temperature friction testing machine. The mating pins were N3 alloy, the protective atmosphere was nitrogen (flow rate 5 L / min), the load was 10 N, the frequency was 3 Hz, the running time was 20 min, and the experimental temperature was 1070℃. The results showed that the lubricant had a relatively low average coefficient of friction, approximately 0.21, as shown in the friction coefficient curve below. Figure 6 As shown; the dual surface morphology diagram is as follows. Figure 7 As shown, the surface is dominated by fine, shallow cross-shaped grinding marks and large polished areas, with very few deep grooves / peeling, indicating that a relatively continuous and dense transfer / oxide film has been formed.

[0044] Example 3 This embodiment is a high-temperature lubricant for vacuum isothermal forging process, which is made of the following components: surface-activated boron nitride powder (28 wt.%), molybdenum disulfide microsphere powder (8 wt.%), glass powder (10 wt.%), potassium silicate (5 wt.%), silica gel (2 wt.%), feldspar powder (12 wt.%), leveling agent (1.5 wt.%), corrosion inhibitor (1 wt.%), dispersant (2 wt.%), defoamer (1 wt.%), and the balance being water.

[0045] The surface-activated boron nitride powder was prepared by mixing boron nitride powder with 20 wt.% NaOH solution, urea, and silane coupling agent (KH550 amino-type silane coupling agent (3-aminopropyltriethoxysilane, purity 98%)) in a mass ratio of 100:60:5:10. The glass powder consisted of 63% SiO2, 10% Na2O, 10% Al2O3, 9% CaO, 5% MgO, 1% ZrO2, and 1% NiO. Made from 2%. Feldspar powder is composed of sodium feldspar (NaAlSi3O8 50%), potassium feldspar (KAlSi3O8 40%), and aluminosilicate (Al2SiO8 10%); leveling agent is composed of acrylic resin (45%), polyvinyl alcohol (35%), and polyether polyol (20%); preservative is composed of benzotriazole (50%), thiol compounds (40%), and organomolybdenum compounds (10%); dispersant is composed of polyacrylic acid (60%), polyvinyl alcohol (20%), and silane compounds (20%); defoamer is composed of silicone oil (45%), fatty acid esters (35%), and polyether compounds (20%).

[0046] The preparation method of high-temperature lubricant includes the following steps: First, potassium silicate is dispersed in water and stirred magnetically for 30 min at 400 rpm. Silica gel is added and stirring is continued for 120 min. Then, surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder, and dispersant are added sequentially. The mixture is ball-milled in a ball mill for 6 h at 400 rpm. After ball milling, leveling agent, corrosion inhibitor, and defoamer are added to the material and ball milling continues for 2 h. Finally, a high-temperature lubricant for vacuum isothermal forging process is obtained.

[0047] A lubricating coating was prepared using the lubricant obtained in Example 3, and its lubrication performance was tested. The method was as follows: the sample to be tested, FGH4169, was heated to 130°C in a protective atmosphere furnace. o At temperature C, after holding at a constant temperature for 1 hour, the lubricant prepared above was applied to the surface of the blank by air spraying. Natural cooling was then performed to obtain a tightly bonded lubricating coating with a thickness of approximately 20 μm. The high-temperature tribological properties of the lubricating coating were then evaluated using an HT-1200 high-temperature friction testing machine. The mating pins were N3 alloy, the protective atmosphere was nitrogen (flow rate 5 L / min), the load was 10 N, the frequency was 3 Hz, the running time was 20 min, and the experimental temperature was 1070℃. The results showed that the average coefficient of friction of the lubricant was relatively low, approximately 0.22, as shown in the friction coefficient curve below. Figure 8 As shown; the dual surface morphology diagram is as follows. Figure 9 As shown, the surface is mainly characterized by fine, shallow intersecting wear marks, with very few deep grooves or spalling.

[0048] Example 4 This embodiment is a high-temperature lubricant for vacuum isothermal forging process, which is made of the following materials: surface-activated boron nitride powder (25 wt.%), molybdenum disulfide microsphere powder (8 wt.%), glass powder (10 wt.%), potassium silicate (5 wt.%), silica gel (2 wt.%), feldspar powder (12 wt.%), leveling agent (4 wt.%), corrosion inhibitor (1 wt.%), dispersant (0.8 wt.%), defoamer (1.5 wt.%), and the balance being water.

[0049] The surface-activated boron nitride powder was prepared by mixing boron nitride powder with 20 wt.% NaOH solution, urea, and silane coupling agent (KH550 amino-type silane coupling agent (3-aminopropyltriethoxysilane, purity 98%)) in a mass ratio of 100:30:15:25. The glass powder consisted of 72% SiO2, 9% Na2O, 5.5% Al2O3, 8% CaO, 3% MgO, 0.6% ZrO2, and NiO. Made from 1.9%. Feldspar powder is composed of sodium feldspar (NaAlSi3O8 45%), potassium feldspar (KAlSi3O8 40%), and aluminosilicate (Al2SiO8 15%); leveling agent is composed of acrylic resin (50%), polyvinyl alcohol (40%), and polyether polyol (10%); preservative is composed of benzotriazole (30%), thiol compounds (40%), and organomolybdenum compounds (30%); dispersant is composed of polyacrylic acid (55%), polyvinyl alcohol (25%), and silane compounds (20%); defoamer is composed of silicone oil (55%), fatty acid esters (35%), and polyether compounds (10%).

[0050] The preparation method of high-temperature lubricant includes the following steps: First, potassium silicate is dispersed in water and stirred magnetically for 30 min at 400 rpm. Silica gel is added and stirring is continued for 120 min. Then, surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder, and dispersant are added sequentially. The mixture is ball-milled in a ball mill for 6 h at 400 rpm. After ball milling, leveling agent, corrosion inhibitor, and defoamer are added to the material and ball milling continues for 2 h. Finally, a high-temperature lubricant for vacuum isothermal forging process is obtained.

[0051] A lubricating coating was prepared using the lubricant obtained in Example 4, and its lubrication performance was tested. The method was as follows: the sample to be tested, FGH4169, was heated to 140°C in a protective atmosphere furnace. o At temperature C, after holding at a constant temperature for 1 hour, the lubricant prepared above was applied to the surface of the blank by air spraying. Natural cooling was then performed to obtain a tightly bonded lubricating coating with a thickness of approximately 20 μm. The high-temperature tribological properties of the lubricating coating were then evaluated using an HT-1200 high-temperature friction testing machine. The mating pins were N3 alloy, the protective atmosphere was nitrogen (flow rate 5 L / min), the load was 10 N, the frequency was 3 Hz, the running time was 20 min, and the experimental temperature was 1070℃. The results showed that the average coefficient of friction of the lubricant was relatively low, approximately 0.26, as shown in the friction coefficient curve below. Figure 10 As shown; the dual surface morphology diagram is as follows. Figure 11As shown, the dual surfaces are mainly characterized by fine, shallow, and nearly parallel wear marks, with localized polishing and very few deep grooves / stripping, indicating the formation of a relatively continuous protective / transfer film. The coefficient of friction is at a low level, suggesting that the high-temperature lubricant significantly weakens adhesion and plowing effects, making wear mainly protected by a slight abrasive-oxide film.

[0052] Example 5 This embodiment is a high-temperature lubricant for vacuum isothermal forging process, which is made of the following materials: surface-activated boron nitride powder (25 wt.%), molybdenum disulfide microsphere powder (5 wt.%), glass powder (8 wt.%), potassium silicate (5 wt.%), silica gel (1 wt.%), feldspar powder (16 wt.%), leveling agent (3 wt.%), corrosion inhibitor (1 wt.%), dispersant (1.5 wt.%), defoamer (1 wt.%), and the balance being water.

[0053] The surface-activated boron nitride powder was prepared by mixing boron nitride powder with 20 wt.% NaOH solution, urea, and silane coupling agent (KH550 amino-type silane coupling agent (3-aminopropyltriethoxysilane, purity 98%)) in a mass ratio of 100:50:10:10. The glass powder consisted of 75% SiO2, 8.2% Na2O, 35% Al2O3, 8% CaO, 3% MgO, 0.5% ZrO2, and NiO. Made from 0.3%. Feldspar powder is composed of sodium feldspar (NaAlSi3O8 40%), potassium feldspar (KAlSi3O8 48%), and aluminosilicate (Al2SiO8 12%); leveling agent is composed of acrylic resin (30%), polyvinyl alcohol (40%), and polyether polyol (30%); preservative is composed of benzotriazole (45%), thiol compounds (25%), and organomolybdenum compounds (30%); dispersant is composed of polyacrylic acid (50%), polyvinyl alcohol (40%), and silane compounds (10%); defoamer is composed of silicone oil (40%), fatty acid esters (40%), and polyether compounds (20%).

[0054] The preparation method of high-temperature lubricant includes the following steps: First, potassium silicate is dispersed in water and stirred magnetically for 30 min at 400 rpm. Silica gel is added and stirring is continued for 120 min. Then, surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder, and dispersant are added sequentially. The mixture is ball-milled in a ball mill for 6 h at 400 rpm. After ball milling, leveling agent, corrosion inhibitor, and defoamer are added to the material and ball milling continues for 2 h. Finally, a high-temperature lubricant for vacuum isothermal forging process is obtained.

[0055] A lubricating coating was prepared using the lubricant obtained in Example 5, and its lubrication performance was tested. The method was as follows: the sample to be tested, FGH4169, was heated to 130°C in a protective atmosphere furnace. oAt temperature C, after holding at a constant temperature for 1 hour, the lubricant prepared above was applied to the surface of the blank by air spraying. Natural cooling was then performed to obtain a tightly bonded lubricating coating with a thickness of approximately 20 μm. The high-temperature tribological properties of the lubricating coating were then evaluated using an HT-1200 high-temperature friction testing machine. The mating pins were N3 alloy, the protective atmosphere was nitrogen (flow rate 5 L / min), the load was 10 N, the frequency was 3 Hz, the running time was 20 min, and the experimental temperature was 1070℃. The results showed that the lubricant had a low average coefficient of friction, approximately 0.27, which was more than 30% lower than that under unlubricated conditions. The coefficient of friction curve is shown below. Figure 12 As shown; the dual surface morphology diagram is as follows. Figure 13 As shown, relatively uniform wear marks appeared on the surface, but compared with the case without the addition of high-temperature lubricant, the wear marks were shallower and smoother, indicating that the addition of lubricant effectively reduced surface friction and wear.

[0056] Comparative Example 1 A lubricating coating was prepared using commercially available lubricating materials containing glass powder, and its lubrication performance was tested. The method was as follows: The sample FGH4169 was heated to 100℃ in a protective atmosphere furnace and held for 1 hour. A commercially available lubricant containing glass powder was then applied to the surface of the blank via air spraying. Natural cooling was then performed to obtain a tightly bonded lubricant coating with a thickness of approximately 20 μm. The high-temperature tribological properties of the lubricant coating were then evaluated using an HT-1200 high-temperature friction testing machine. The mating pins were N3 alloy, the protective atmosphere was nitrogen (flow rate 5 L / min), the load was 10 N, the frequency was 3 Hz, the running time was 20 min, and the experimental temperature was 1070℃. The results showed that the average coefficient of friction of the lubricant was approximately 0.37, and the friction coefficient curve is shown below. Figure 14 As shown; the dual surface morphology diagram is as follows. Figure 15 As shown, the appearance of grooves, patchy tears, and discontinuous transfer films on the dual surface in the same direction as the sliding indicates that the wear is mainly adhesive-abrasive composite wear accompanied by local fatigue spalling. Due to the non-dense transfer film and the presence of plowing grooves, the friction coefficient remains at a high level.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A high-temperature lubricant for vacuum isothermal forging processes, characterized in that, It is made from the following raw materials: 25-35 wt.% surface-activated boron nitride powder, 5-8 wt.% molybdenum disulfide microsphere powder, 8-10 wt.% glass powder, 5 wt.% potassium silicate, 1-2 wt.% silica gel, 10-16 wt.% feldspar powder, 1.5-4 wt.% leveling agent, 1-1.5 wt.% preservative, 0.8-2 wt.% dispersant, 1-1.5 wt.% defoamer, and the balance being water.

2. The high-temperature lubricant for vacuum isothermal forging process according to claim 1, characterized in that, The preparation method of the surface-activated boron nitride powder is as follows: Boron nitride powder was mixed with alkaline solution, urea and silane coupling agent. The mixture was then placed in a ball mill for mechanochemical activation treatment. Stainless steel balls were used as the milling medium, with a ball-to-material ratio of (20-60):

1. The ball mill speed was 300-500 rpm and the milling time was 6-18 h to obtain surface-activated boron nitride powder. The boron nitride powder has a particle size of 0.5-20 μm and a purity of 99.5%. The alkaline solution is a 20 wt.% NaOH solution; The silane coupling agent is KH550 amino-type silane coupling agent with a purity of 98%; The mass ratio of boron nitride powder, alkaline solution, urea, and silane coupling agent is 100:(20-60):(5-30):(10-25). The diameter of the stainless steel ball is 5-10 mm.

3. The high-temperature lubricant for vacuum isothermal forging process according to claim 1, characterized in that, The preparation method of the molybdenum disulfide microsphere powder is as follows: Ammonium molybdate and sulfur are mixed at a molar ratio of 1:2 and heated to 300-500℃ in an inert atmosphere to produce molybdenum disulfide. After the reaction is complete, the product is cooled to room temperature and washed with deionized water or alcohol solvent to remove unreacted raw materials or byproducts. The washed molybdenum disulfide powder is dried at 60-100℃, ball-milled, and sieved to control the particle size at 5-10 μm to obtain molybdenum disulfide microsphere powder.

4. The high-temperature lubricant for vacuum isothermal forging process according to claim 1, characterized in that, The method for preparing the glass powder is as follows: First, the raw materials are mixed according to the following ratio: SiO2 55-75%, Na2O 8-10%, Al2O3 5-10%, CaO 8-10%, MgO 3-5%, ZrO2 0.5-1%, NiO 0.3-2%. The mixed raw materials are then fed into a high-temperature furnace and melted at a temperature of 1350-1450℃ to generate molten glass. Subsequently, the molten glass is cooled into solid glass blocks by rapid cooling or natural cooling. The cooled glass blocks are then crushed and ground into fine powder. After sieving, the particle size is controlled to be 5-10 μm to obtain glass powder.

5. The high-temperature lubricant for vacuum isothermal forging process according to claim 1, characterized in that, The feldspar powder is composed of 40-50% sodium feldspar (NaAlSi3O8), 40-50% potassium feldspar (KAlSi3O8), and 10-20% aluminosilicate (Al2SiO8). The leveling agent is composed of 30-50% acrylic resin, 20-40% polyvinyl alcohol, and 10-30% polyether polyol; The preservative is composed of 30-50% benzotriazole, 20-40% thiols and 10-30% organomolybdenum compounds; The dispersant is composed of 40-60% polyacrylic acid, 20-40% polyvinyl alcohol, and 10-20% silane compounds; The defoamer is composed of 40-60% silicone oil, 20-40% fatty acid esters, and 10-20% polyether compounds.

6. A method for preparing a high-temperature lubricant for vacuum isothermal forging process according to any one of claims 1 to 5, characterized in that, First, potassium silicate is dispersed in water and stirred for 30 minutes at 400 rpm. Silica gel is added and stirring continues for 60-240 minutes. Then, surface-activated boron nitride powder, molybdenum disulfide microsphere powder, glass powder, feldspar powder, and dispersant are added sequentially. The mixture is then ball-milled for 6 hours at 400 rpm. After ball milling, leveling agent, corrosion inhibitor, and defoamer are added to the material, and ball milling continues for 2 hours. Finally, a high-temperature lubricant for vacuum isothermal forging is obtained.

7. The application of the high-temperature lubricant according to claim 6 in a vacuum isothermal forging process.

8. The application according to claim 7, characterized in that, The method for preparing the lubricating coating is as follows: Heat the forging to 90-140 degrees Celsius. o C, keep warm for 1 hour, apply the high-temperature lubricant to the surface of the forging by air spraying, and obtain a tightly bonded lubricating coating on the surface of the forging after natural cooling.

9. The application according to claim 8, characterized in that, The thickness of the lubricating coating is 20~30μm.

10. The application according to claim 9, characterized in that, The average coefficient of friction of the high-temperature lubricant is less than 0.27.

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