Glass lubricant for vacuum isothermal forging, preparation method for glass lubricant slurry, and coating method for glass lubricant slurry

Abstract

The present application relates to a glass lubricant for vacuum isothermal forging, a preparation method for a glass lubricant slurry, and a coating method for the glass lubricant slurry. The glass lubricant comprises the following components: 50-52 wt% of SiO2, 13-15 wt% of B2O3, 10-12 wt% of Al2O3, 8-9 wt% of CaO, 3-5 wt% of Na2O, 2-3 wt% of MgO, 2-3 wt% of BaO, and 2-3 wt% of Fe2O3. By means of the reasonable compounding of the formula of the glass lubricant of the present invention, the glass lubricant is particularly suitable for a forging process at 950-1200°C in vacuum isothermal forging, so that the glass body formed by the glass lubricant has proper viscosity in vacuum, high-pressure, high-temperature and closed environments of vacuum isothermal forging, and has good wettability on a metal blank, particularly a powder high-temperature alloy, and a uniform and complete glass film can be formed on the surface of the metal blank, thereby providing good lubricating performance.

Description

Glass lubricant for vacuum isothermal forging and slurry preparation method and coating method thereof Technical Field

[0001] The present invention relates to the field of powder high-temperature alloy forming, in particular to a glass lubricant for vacuum isothermal forging and a preparation method and a coating method thereof. Background Art

[0002] Vacuum isothermal forging is a high-temperature metal forming process particularly suitable for the preparation of powder high-temperature alloys. High-temperature isothermal forging involves isothermal forging a metal billet in a vacuum environment to achieve the desired shape and properties. The entire process, from heating to forging, takes place within a sealed vacuum chamber, maintaining the same temperature as the billet and die. Vacuum isothermal forging effectively controls the surface quality, internal structure, and oxide content of the forging. Furthermore, the metal strain rate is slow and deformation is uniform during the forging process, resulting in net-shape or near-net-shape forgings.

[0003] Metal blanks and molds are prone to adhesion under the high temperature and high pressure environment of vacuum isothermal forging, which seriously affects the forging effect. Therefore, it is necessary to apply a lubricant between the metal and the mold. Glass lubricant is a common lubricant used in metal forging. Glass lubricant usually consists of a slurry composed of glass powder, organic solvent, organic binder, and filler, and is applied to the surface of the blank at room temperature. During the heating process of forging, the organic solvent and other components of the glass lubricant will evaporate, and the glass contained in it, as an amorphous substance, undergoes a gradual softening and melting process from solid state - softening - semi-fluid - fluid. When the forging temperature is reached, the glass lubricant forms a continuous and dense film on the surface of the metal blank, isolating the metal surface and the mold, and playing the role of fluid lubrication. However, in practice, it is found that existing glass lubricants cannot achieve good lubrication in the vacuum, high pressure and high temperature working environment of vacuum isothermal forging.

[0004] For example, Chinese patent document CN 111423127 A provides a method for preparing glass powder and glass powder. Raw materials are weighed and mixed to obtain a mixture, the mixture is heated and melted, and the mixture is cooled and melted before grinding to obtain glass powder. By adding cosolvents such as Li2O, Na2O, and CaF2 to the formula raw materials, the softening temperature and melting temperature of the glass body are reduced, and a multiphase composite system of microcrystalline phase and glass phase is easily formed. However, when the glass powder is applied to vacuum isothermal forging, it is found that the melting temperature of the glass powder is too low, and its viscosity is too low at the working temperature of vacuum isothermal forging, and it is easy to lose, and effective lubrication cannot be achieved between the metal blank and the mold. In addition, the formula of the invention contains a large amount of bismuth oxide, which may introduce impurities into the metal blank.

[0005] Chinese patent document CN 102703200 A discloses a formula for a surface protection lubricant for isothermal forging processes of high-temperature alloys. The invention adopts a composite glass design concept, using glass A, glass B and glass C with different degrees of difficulty in melting as composite glass base materials. By rationally matching the performance of the three types of glass, a perfect relay effect is achieved in the entire temperature range from low temperature to high temperature, excellent anti-oxidation performance is achieved during the heating process, and good lubrication performance is achieved during forging. However, when the glass lubricant was applied to vacuum isothermal forging, it was found that the glass lubricant had poor film-forming properties and could not form a complete glass film on the surface of the metal blank, and could not achieve effective lubrication between the metal blank and the mold. In addition, the invention uses three types of glass to form a composite glass, which is complex in process and high in cost.

[0006] Chinese patent document CN 105132103 A discloses a glass protective lubricant powder and coating for titanium alloy die forging. The lubricant in this invention has an operating temperature of 700-1000°C. The glass powder begins to melt at 700°C and stops flowing at 1000°C, providing both anti-oxidation and lubrication for the titanium alloy surface. However, when the glass powder was applied to vacuum isothermal forging, it was found that its melting temperature was relatively low, its viscosity was low at the operating temperature of the vacuum isothermal forging, and its film-forming properties were poor, making it impossible to achieve effective lubrication between the metal blank and the die.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a glass lubricant for vacuum isothermal forging and a preparation method and coating method thereof. The glass lubricant is particularly suitable for the vacuum, high pressure, high temperature and closed environment of vacuum isothermal forging, and can promote the flow of blank metal and improve the surface quality of the formed part.

[0009] An object of the present invention is to provide a glass lubricant for vacuum isothermal forging, which comprises the following components: 50-52 wt% SiO2, 13-15 wt% B2O3, 10-12 wt% Al2O3, 8-9 wt% CaO, 3-5 wt% Na2O, 2-3 wt% MgO, 2-3 wt% BaO and 2-3 wt% Fe2O3.

[0010] The glass lubricant of the present invention is rationally formulated and is particularly suitable for vacuum isothermal forging processes at 950-1200° C., so that the glass body formed by the glass lubricant has suitable viscosity in the vacuum, high pressure, high temperature and closed environment of vacuum isothermal forging, and has good wettability to metal blanks or workpieces to be forged (especially powder high-temperature alloys), and can form a uniform and complete glass film on the surface of the metal blank, thereby providing good lubrication performance.

[0011] In one embodiment of the present invention, the glass lubricant includes the following components: 52 wt% SiO2, 13 wt% B2O3, 12 wt% Al2O3, 9 wt% CaO, 5 wt% Na2O, 3 wt% MgO, 3 wt% BaO, and 3 wt% Fe2O3.

[0012] Another object of the present invention is to provide a method for preparing a glass lubricant slurry for vacuum isothermal forging, comprising the following steps: preparing glass powder raw materials according to the above-mentioned component ratios of the glass lubricant; uniformly mixing the glass powder raw materials using a mixer; heating the uniformly mixed glass powder raw materials at a temperature of 1300-1400°C for at least 5 hours to form a uniform molten glass liquid; cooling the molten glass liquid with the aid of water to form a glass solid; ball-milling the glass solid to form a glass powder; and mixing the glass powder with water, an organic binder, and clay to form a glass lubricant slurry.

[0013] The preparation method of the glass lubricant slurry of the present invention is simple and cost-effective. Only common mixing, heating, and ball milling equipment are required to obtain the desired glass powder, and thus the desired glass lubricant slurry. This is particularly advantageous for the application of the glass lubricant, as the glass lubricant can be conveniently prepared on-site before actual use, without the need for specialized equipment or personnel training. It is important to note that because the glass lubricant slurry contains volatile components such as an organic binder, it should be stored sealed after preparation unless immediately used.

[0014] In some embodiments of the present invention, the ball milling speed is 200 r / min and the ball milling time is 3 h.

[0015] In some embodiments of the present invention, the mixing percentage of the glass powder, the water, the organic binder and the clay is: 60-70 wt % of glass powder, 25-35 wt % of water, 2-4 wt % of organic binder and 1-5 wt % of clay.

[0016] In some embodiments of the present invention, the water is distilled water, and the organic binder is methyl cellulose.

[0017] Based on the above, the service life of the glass body formed by the glass lubricant slurry in the vacuum, high pressure, high temperature and closed environment of vacuum isothermal forging is further increased, and its service effect is further improved.

[0018] Another object of the present invention is to provide a glass lubricant slurry for vacuum isothermal forging, which is prepared by any of the above-mentioned methods for preparing the glass lubricant slurry.

[0019] Another object of the present invention is to provide a method for coating a glass lubricant slurry for vacuum isothermal forging, comprising the following steps: uniformly coating the glass lubricant slurry on the surface of a blank, wherein the glass lubricant slurry is a mixture of any of the above-mentioned glass lubricants and an organic solvent, or the glass lubricant slurry is any of the above-mentioned glass lubricant slurries; placing the workpiece coated with the glass lubricant slurry in a heater, heating it to 650-700°C at a heating rate of 10°C / min, and keeping it warm for at least 1 hour; and slowly cooling the workpiece coated with the glass lubricant slurry.

[0020] The coating method of the present invention can easily form a complete glass lubricating film on the surface of a complex workpiece, provide sufficient lubricant for subsequent vacuum isothermal forging, and provide a good lubricating effect.

[0021] In some embodiments of the present invention, before applying the glass lubricant slurry to the surface of the workpiece, the workpiece is preheated to 180-200° C.

[0022] In some embodiments of the present invention, the thickness of the glass lubricant slurry coated on the surface of the workpiece is 30-50 μm.

[0023] As a result, it is further helpful to form a uniform and complete glass lubricating film on the surface of the complex workpiece, providing the desired amount of lubricant for the subsequent vacuum isothermal forging, further improving the lubrication effect and improving the surface quality of the formed part.

[0024] The above content of the present invention will be more clearly understood in the following description of multiple embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following are the drawings of the present invention. These drawings are only for illustrating the present invention in a more intuitive form. They are exemplary and are not intended to limit the scope of the present invention.

[0026] FIG1 is a schematic flow chart of an embodiment of a method for preparing a glass lubricant slurry according to the present invention.

[0027] FIG. 2 is a schematic flow chart of an embodiment of a coating method according to the present invention. DETAILED DESCRIPTION

[0028] In order to make the present invention easier to understand, the present invention is further described below with reference to specific examples. The experimental methods described in the present invention are conventional methods unless otherwise specified; the materials described are commercially available unless otherwise specified. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In the event of any inconsistency, the meanings described in this specification or the meanings derived from the contents recorded in this specification shall prevail. In addition, the terms used herein are for the purpose of describing the embodiments of the present invention only and are not intended to limit the present invention.

[0029] In order to accurately describe the technical contents of the present invention and to accurately understand the present invention, the following explanations of the words and terms used in this specification are given before describing the specific implementation methods.

[0030] As used in this specification, the phrases "one embodiment" or "an embodiment" mean that a particular feature, step, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment, but may do so. Furthermore, in one or more embodiments, the particular features, steps, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0031] During the vacuum isothermal forging process, the press has a large tonnage, a slow speed, and a long forging time. The high temperature intensifies the movement and diffusion speed of molecules, which increases the friction between the metal blank and the mold, resulting in the occurrence of metal blank sticking to the mold. In addition, vacuum isothermal forging is carried out in a closed cavity, and the lubricant cannot be replenished in real time. These pose challenges to the lubricant formulation and coating process of vacuum isothermal forging. However, the existing glass lubricants cannot achieve good lubrication in the vacuum, high pressure and high temperature working environment of vacuum isothermal forging. The inventors have found in practice that the wettability of existing glass lubricants in a vacuum environment is generally worse than that in an atmospheric pressure environment. This makes it impossible for existing glass lubricants to fully wet the metal blank in a vacuum environment, that is, it is impossible to form a complete glass lubricating film on the surface of the metal blank, and it is impossible to avoid the occurrence of sticking to the mold. In addition, the inventors also found that some existing glass lubricants have too low viscosity at the service temperature of vacuum isothermal forging, which not only makes them easily leak from the mold, but also seriously affects the wettability and film-forming properties; while other existing glass lubricants are configured to have a dense texture to prevent the metal blank from reacting with oxygen, hydrogen, etc., resulting in their high-temperature viscosity being too high, and the lubrication effect being significantly reduced, which cannot meet actual needs.

[0032] Based on the above findings, the inventors have designed a formula for a glass lubricant for vacuum isothermal forging, which is particularly suitable for a forging process of 950-1200°C in vacuum isothermal forging, so that the glass body formed by the glass lubricant has a suitable viscosity in the vacuum, high pressure, high temperature and closed environment of vacuum isothermal forging, and has good wettability to the metal blank or the workpiece to be forged (especially powder high-temperature alloys), and can form a uniform and complete glass film on the surface of the metal blank, thereby providing good lubrication performance. The inventors have also designed a method for preparing a glass lubricant slurry for vacuum isothermal forging, which is simple in process and low in cost. It only requires the use of common mixing, heating and ball milling equipment to obtain glass powder that meets the requirements, and then obtain a glass lubricant slurry that meets the requirements. In addition, the inventors have also designed a coating method for a glass lubricant slurry for vacuum isothermal forging, which can easily form a complete glass lubricating film on the surface of a complex workpiece, providing sufficient lubricant for subsequent vacuum isothermal forging and providing a good lubrication effect.

[0033] For ease of implementation, exemplary embodiments of the glass lubricant, the preparation method of the glass lubricant slurry, and the coating method of the present invention are described below.

[0034] <Example 1>

[0035] The glass lubricant of this embodiment includes the following components: 52 wt % SiO 2 , 13 wt % B 2 O 3 , 12 wt % Al 2 O 3 , 9 wt % CaO, 5 wt % Na 2 O, 3 wt % MgO, 3 wt % BaO, and 3 wt % Fe 2 O 3 .

[0036] The preparation method of the glass lubricant slurry of this embodiment includes the following steps: preparing glass powder raw materials according to the component ratio of the above-mentioned glass lubricant; using a mixer to uniformly mix the glass powder raw materials for 3 hours; pouring the uniformly mixed glass powder raw materials into a corundum crucible, placing it in a muffle furnace and heating it to 1400°C at a heating rate of 10°C / min, and keeping it at this temperature for 5 hours until the glass powder forms a uniform molten glass liquid; pouring the molten glass liquid from the corundum crucible into room temperature distilled water and rapidly cooling it to form a glass solid; fishing out the glass solid in the distilled water with a 200 mesh sieve; ball milling it with a planetary ball mill at a speed of 200 r / min for 3 hours to form glass powder; and stirring and mixing the glass powder, distilled water, methyl cellulose and clay at percentages of 65wt%, 30wt%, 3wt% and 2wt% to form a glass lubricant slurry.

[0037] 2 , the coating method of this embodiment includes the following steps: 201. Immediately apply the glass lubricant slurry prepared according to the above preparation method to the surface of the workpiece to form a complete and uniform coating with a thickness of 30 μm on the surface of the workpiece; 202. Place the workpiece coated with the glass lubricant slurry in a heater and heat it to 650° C. at a heating rate of 10° C. / min, i.e., reach the softening point of the glass lubricant, and keep it warm for 1 hour to volatilize the organic binder in the slurry and enable the glass body to adhere to the metal surface to form a complete glass lubricating film; 203. Cool the calcined workpiece with the furnace to slowly lower the temperature to avoid the glass body formed on the surface of the workpiece from collapsing due to the sudden increase in internal tensile stress due to the sudden drop in temperature; 204. Place the workpiece into a vacuum isothermal forging cavity to perform subsequent forging operations.

[0038] <Example 2>

[0039] The glass lubricant of this embodiment includes the following components: 52 wt % SiO 2 , 15 wt % B 2 O 3 , 10 wt % Al 2 O 3 , 9 wt % CaO, 5 wt % Na 2 O, 3 wt % MgO, 3 wt % BaO, and 3 wt % Fe 2 O 3 .

[0040] The preparation method of the glass lubricant slurry of this embodiment is shown in FIG1 and includes the following steps: 101. preparing glass powder raw materials according to the component ratio of the above-mentioned glass lubricant; 102. using a mixer to uniformly mix the glass powder raw materials for 3.5 hours; 103. pouring the uniformly mixed glass powder raw materials into a corundum crucible, heating the glass powder raw materials in a muffle furnace at a heating rate of 10°C / min to 1400°C, and keeping the temperature at this temperature for 5.5 hours until the glass powder forms a uniform molten glass liquid; 104. removing the molten glass liquid from the corundum crucible; Pour room temperature distilled water into the crucible and rapidly cool it to form a glass solid; 105. Use a 200-mesh sieve to fish out the glass solid from the distilled water; 106. Use a planetary ball mill to ball mill the glass solid at a speed of 150 r / min for 4 hours to form glass powder; 107. Stir and mix the glass powder, distilled water, methyl cellulose, and clay in proportions of 65 wt%, 30 wt%, 3 wt%, and 2 wt% to form a glass lubricant slurry; 108. Seal and store the glass lubricant slurry.

[0041] The coating method of this embodiment includes the following steps: preheating the workpiece to 200°C; spraying the glass lubricant slurry prepared according to the above preparation method onto the surface of the workpiece to form a complete and uniform coating with a thickness of 40 μm on the surface of the workpiece; placing the workpiece coated with the glass lubricant slurry in a heater and heating it to 700°C at a heating rate of 10°C / min, that is, reaching the softening point of the glass lubricant, and keeping it warm for 1 hour to volatilize the organic binder in the slurry and allow the glass body to adhere to the metal surface; cooling the calcined workpiece with the furnace to slowly reduce the temperature to avoid the glass body formed on the surface of the workpiece from collapsing due to the sudden increase in internal tensile stress due to the sudden drop in temperature. Optionally, the metal workpiece with the glass body attached to the surface is then placed in a vacuum preheating furnace and preheated to 1000°C, and then placed in a vacuum isothermal forging cavity to perform subsequent forging operations.

[0042] <Example 3>

[0043] The glass lubricant of this embodiment includes the following components: 51 wt % SiO 2 , 15 wt % B 2 O 3 , 12 wt % Al 2 O 3 , 9 wt % CaO, 4 wt % Na 2 O, 3 wt % MgO, 3 wt % BaO, and 3 wt % Fe 2 O 3 .

[0044] The preparation method of the glass lubricant slurry of this embodiment includes the following steps: preparing glass powder raw materials according to the component ratios of the glass lubricant described above; uniformly mixing the glass powder raw materials in a mixer for 3.5 hours; pouring the uniformly mixed glass powder raw materials into a corundum crucible, heating the glass powder raw materials in a muffle furnace at a heating rate of 10°C / min to 1350°C, and maintaining the temperature at this temperature for 5 hours until the glass powder forms a uniform molten glass liquid; pouring the molten glass liquid from the corundum crucible into room temperature distilled water and rapidly cooling it to form a glass solid; fishing the glass solid out of the distilled water and ball milling it in a planetary ball mill at a speed of 200 rpm for 5 hours to form glass powder; and stirring and mixing the glass powder, distilled water, methyl cellulose, and clay in proportions of 65wt%, 30wt%, 3wt%, and 2wt% to form a glass lubricant slurry. The glass lubricant slurry is then sealed and stored.

[0045] The coating method of this embodiment includes the following steps: preheating the workpiece to 200°C; spraying the glass lubricant slurry prepared according to the above preparation method onto the surface of the workpiece to form a complete and uniform coating with a thickness of 50 μm on the surface of the workpiece; placing the workpiece coated with the glass lubricant slurry in a heater and heating it to 680°C at a heating rate of 10°C / min, that is, reaching the softening point of the glass lubricant, and keeping it warm for 1 hour to volatilize the organic binder in the slurry and allow the glass body to adhere to the metal surface; cooling the calcined workpiece with the furnace to slowly reduce the temperature to avoid the glass body formed on the surface of the workpiece from collapsing due to the sudden increase in internal tensile stress due to the sudden drop in temperature. Optionally, the metal workpiece with the glass body attached to the surface is then placed in a vacuum preheating furnace and preheated to 1000°C, and then placed in a vacuum isothermal forging cavity to perform subsequent forging operations.

[0046] <Experimental Example>

[0047] The glass lubricant slurry prepared in Example 1 was applied to the surface of a FHG96 workpiece with a size of 15*30mm. The dynamic wetting angle of the glass lubricant on the surface of the FGH96 workpiece was photographed and measured using a DataPhysics OCA high-temperature contact angle tester. It was found that the glass lubricant of the present invention exists in the form of a mixture of solid particles, plastic viscous substances, molten glass liquid, etc. in the temperature range of 840-1200°C, and has a good wetting effect on the metal blank. The final wetting angle is 18.3° at 1200°C. The high-temperature viscosity curve of the lubricant was also measured, and its temperature-viscosity curve shows that its viscosity is 10 at 950°C. 4 Poise, its viscosity is 10 at 1150℃ 3 According to the empirical formula, here 10 3 ~10 4 The viscosity range meets the performance requirements of isothermal forging lubricants.

[0048] According to the coating method of Example 1, the glass lubricant slurry prepared in this example was coated on the surface of a cylindrical FHG96 workpiece. The workpiece coated with the glass lubricant slurry was subjected to vacuum isothermal upsetting at 950°C and 10 -3 S -1 The friction coefficient obtained at the strain rate was 0.13. This demonstrates that the glass lubricant of the present invention is suitable for isothermal forging in a vacuum environment, with the measured friction coefficient comparable to that in atmospheric conditions. After the experiment, the die on the press did not adhere to the blank surface, demonstrating excellent demolding performance, demonstrating that the lubricant meets the process requirements for vacuum isothermal forging.

Claims

1. A glass lubricant for vacuum isothermal forging, characterized in that: It includes the following components: 50-52wt% SiO2, 13-15wt% B2O3, 10-12wt% Al2O3, 8-9wt% CaO, 3-5wt% Na2O, 2-3wt% MgO, 2-3wt% BaO and 2-3wt% Fe2O3.

2. The glass lubricant according to claim 1, characterized in that: The composition includes: 52wt% SiO2, 13wt% B2O3, 12wt% Al2O3, 9wt% CaO, 5wt% Na2O, 3wt% MgO, 3wt% BaO and 3wt% Fe2O3.

3. A method for preparing a glass lubricant slurry for vacuum isothermal forging, characterized in that: The following steps are involved: Prepare glass powder raw material according to the component ratio of the glass lubricant according to claim 1 or 2; Using a mixer to evenly mix the glass powder raw materials; Heating the uniformly mixed glass powder raw materials at a temperature of 1300-1400° C. for at least 5 hours to form a uniform molten glass liquid; Cooling the molten glass liquid by means of water to form a glass solid; ball milling the glass solid to form glass powder, and The glass powder is mixed with water, an organic binder and clay to form a glass lubricant slurry.

4. The preparation method according to claim 3, characterized in that: The rotation speed of the ball mill is 200 r / min, and the ball milling time is 3 h.

5. The preparation method according to claim 3, characterized in that: The mixing percentage of the glass powder, the water, the organic binder and the clay is: 60-70wt% of the glass powder, 25-35wt% of the water, 2-4wt% of the organic binder and 1-5wt% of the clay.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The water is distilled water, and the organic binder is methyl cellulose.

7. A glass lubricant slurry for vacuum isothermal forging, characterized in that: Prepared by the preparation method described in any one of claims 3 to 6.

8. A method for coating glass lubricant slurry for vacuum isothermal forging, characterized in that: The following steps are involved: uniformly applying a glass lubricant slurry to the surface of the workpiece, wherein the glass lubricant slurry is the glass lubricant slurry according to claim 7; Placing the workpiece coated with the glass lubricant slurry in a heater, heating to 650-700° C. at a heating rate of 10° C. / min, and keeping the temperature for at least 1 hour; and The workpiece coated with the glass lubricant slurry is slowly cooled.

9. The coating method according to claim 8, characterized in that: Before applying the glass lubricant slurry to the surface of the workpiece, the workpiece is preheated to 180-200°C.

10. The coating method according to claim 8 or 9, characterized in that: The thickness of the glass lubricant slurry coated on the surface of the workpiece is 30-50 μm.

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