Lubricating method for plastic forming of niobium-tungsten alloy

Abstract

The invention discloses a lubricating method for plastic forming of niobium-tungsten alloy, and relates to the technical field of alloy processing lubrication, the lubricating method comprises the following steps: S1, carrying out cyanide-free copper electroplating treatment on a niobium-tungsten alloy workpiece; s2, the niobium-tungsten alloy workpiece subjected to cyanide-free copper electroplating treatment is extruded, an oil-based lubricant is used for lubrication during extrusion, and the oil-based lubricant comprises, by mass, 68% of oleic acid, 16% of graphite and 16% of molybdenum disulfide; and S3, the niobium-tungsten alloy subjected to extrusion plastic forming is subjected to electroplating copper removing treatment. Continuous and stable lubrication can be provided under the high contact load in the plastic forming process, contact friction between a niobium-tungsten alloy workpiece and a mold is effectively reduced, damage to the mold and the niobium-tungsten alloy workpiece is reduced, the plastic forming quality is improved, and operation is easy.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy processing lubrication, and particularly to a lubrication method for plastic forming of niobium-tungsten alloy. Background Art

[0002] Due to the high yield strength and high work hardening rate of niobium-tungsten alloy, during cold forming, there is a large contact load between the niobium-tungsten alloy workpiece and the die, resulting in a large forming force and difficult forming. Although lubrication can reduce friction and forming force, the chemical inertness of niobium-tungsten alloy limits the application of conventional lubrication treatment methods (such as phosphating, oxalate-fluoride, etc.), and conventional lubricants (such as lubricant powders like graphite, or lubricating oils like rapeseed oil, chlorinated paraffin oil, etc.) are easily extruded from the die under high loads, making it difficult to ensure the lubrication effect during the extrusion process. While hot forming (300 - 500°C) can reduce the forming force compared to cold forming, the surface of niobium-tungsten alloy oxidizes at 300°C, and oxidation powdering occurs on the surface above 500°C. To avoid this problem, the existing treatment method can use glass lubricant for lubrication, which can change into a high-viscosity melt state within a certain temperature range to wrap the niobium-tungsten alloy workpiece and isolate air. However, it is difficult to control the thickness of the lubricating film with glass lubricant, and it needs to be coated before each extrusion, and cannot be prefabricated on the surface of the niobium-tungsten alloy workpiece in advance. The process is relatively complex, and the glass lubricant is also easily adhered to the surfaces of the niobium-tungsten alloy workpiece and the die during extrusion, and it is troublesome to remove, and it is easy to damage the niobium-tungsten alloy workpiece. Summary of the Invention

[0003] The purpose of the present invention is to provide a lubrication method for plastic forming of niobium-tungsten alloy, which can provide continuous and stable lubrication during the plastic forming process, effectively reduce the contact friction between the niobium-tungsten alloy workpiece and the die, and improve the quality of plastic forming.

[0004] To achieve the above purpose, the core idea of the present invention is: electroplate a copper thin film on the surface of the niobium-tungsten alloy workpiece before denaturation through non-cyanide electroplating technology. During electroplating, after activation treatment, etching micropits will be generated on the surface of the niobium-tungsten alloy substrate, and the copper element of the copper thin film will be embedded in these etching micropits to generate mechanical embedding with the niobium-tungsten alloy substrate, thereby enhancing the bonding degree between the copper thin film and the niobium-tungsten alloy substrate. Since the copper thin film has good ductility, it can flow with the niobium-tungsten alloy workpiece during denaturation, ensuring continuous and stable lubrication during the extrusion process. In addition, during extrusion, lubrication is combined with oleic acid added with graphite and molybdenum disulfide, which can further improve the lubrication effect during the extrusion process of the niobium-tungsten alloy workpiece.

[0005] Specifically, the solution of the present invention is: a lubrication method for plastic forming of niobium-tungsten alloy, the lubrication method comprising the following steps: S1: Perform cyanide-free electroplating copper treatment on the niobium-tungsten alloy workpiece; S2: Extrude the niobium-tungsten alloy workpiece that has completed the cyanide-free electroplating copper treatment. Use an oil-based lubricant for lubrication during extrusion. The mass fraction ratio of this oil-based lubricant is: 68% oleic acid, 16% graphite, and 16% molybdenum disulfide; S3: Perform electroplating copper stripping treatment on the niobium-tungsten alloy that has completed extrusion plastic forming.

[0006] Preferred solution, in steps S1 and S3, an electroplating device is used. The electroplating device is provided with an electroplating tank for containing electroplating solution, and an anode and a cathode are arranged in the electroplating tank; The cyanide-free electroplating copper treatment in step S1 includes the following steps: S11: Degreasing: Immerse the niobium-tungsten alloy workpiece in an alkaline solution at 60 °C. The ratio of this alkaline solution includes: 80 g / L sodium hydroxide, 30 g / L trisodium phosphate, 30 g / L sodium carbonate, and 1 g / L sodium silicate. Stop degreasing when the surface of the niobium-tungsten alloy workpiece shows a uniform metallic color; S12: Rinsing: Rinse the degreased niobium-tungsten alloy workpiece in clean water at 20 °C; S13: Pickling: Immerse the rinsed niobium-tungsten alloy workpiece in a pickling solution at 20 °C. The pickling time is 1 - 2 min. The mass fraction ratio of this pickling solution is: 10% hydrofluoric acid, 40% nitric acid, and 50% distilled water; S14: Ultrasonic cleaning: Immerse the pickled niobium-tungsten alloy workpiece in clean water at 50 °C, and use an ultrasonic cleaning machine to perform ultrasonic cleaning on the niobium-tungsten alloy workpiece. The cleaning time is 1 - 2 min; S15: Electroplating copper: The electroplating solution is a cyanide-free electroplating solution. The anode is a pure copper plate, and the cathode is the niobium-tungsten alloy workpiece that has undergone degreasing, rinsing, pickling, and ultrasonic cleaning. The part of the niobium-tungsten alloy workpiece immersed in the cyanide-free electroplating solution is bundled and connected with pure titanium wire and then electroplating copper treatment is carried out.

[0007] Preferred solution, the purities of sodium hydroxide, trisodium phosphate, and sodium carbonate in step S11 are all analytical pure, and the purities of hydrofluoric acid and nitric acid in step S13 are all analytical pure.

[0008] Preferred solution, in step S15, the distance between the anode and the cathode is 50 - 60 mm, the anode area is twice the cathode area, and the current density is 1.3 - 1.5 A / dm 3 .

[0009] Preferred solution: The electroplating copper stripping treatment in step S3 is as follows: the electroplating solution is a copper stripping solution, the temperature of the copper stripping solution is 20°C, the anode is a niobium-tungsten alloy workpiece that has completed electroplating copper treatment and has been subjected to extrusion plastic forming, the cathode is a stainless steel plate, and the niobium-tungsten alloy workpiece is tied and connected with pure titanium wire and then completely immersed in the copper stripping solution for electroplating copper stripping treatment.

[0010] Preferred solution: The formulation of the copper stripping solution includes: 80 g / L ammonium nitrate and 30 g / L sodium citrate, and the pH value of the copper stripping solution is adjusted to be between 8 and 10 using sodium hydroxide.

[0011] Preferred solution: The purity of the ammonium nitrate is analytical pure.

[0012] Preferred solution: The distance between the anode and the cathode is 50 - 60 mm, and the current density is 2 - 3 A / dm 3 。

[0013] After adopting the above solutions, the beneficial effects of the present invention are as follows: 1. A copper thin film is evenly electroplated on the surface of the niobium-tungsten alloy workpiece using a cyanide-free electroplating technique. This copper thin film has the characteristics of low hardness, low shear strength, and high pressure resistance. During the extrusion process of the niobium-tungsten alloy workpiece, the copper thin film undergoes plastic deformation, thereby providing continuous and stable lubrication during the plastic forming process of the niobium-tungsten alloy workpiece, effectively reducing the contact friction between the niobium-tungsten alloy workpiece and the mold, and improving the quality of plastic forming.

[0014] 2. After the surface of the niobium-tungsten alloy workpiece undergoes activation treatment, etching micro-pits will be generated. During the cyanide-free electroplating copper treatment, copper elements will be embedded in the etching micro-pits to form mechanical interlocking with the niobium-tungsten alloy workpiece, making the combination of the copper thin film and the niobium-tungsten alloy workpiece more firm. It will not be extruded from the mold like a conventional lubricant and lose the lubrication effect under the high contact load during the extrusion process. Moreover, during the extrusion plastic forming process of the niobium-tungsten alloy workpiece, the metal will flow, and the copper thin film on the surface of the niobium-tungsten alloy workpiece will deform and flow accordingly, so that during the extrusion process, the surface of the niobium-tungsten alloy workpiece is always attached with a copper thin film, effectively improving the lubrication effect.

[0015] 3. The hardness of the copper thin film is very low. During the extrusion process, the copper thin film is located between the niobium-tungsten alloy workpiece and the mold, avoiding direct contact between the high-hardness niobium-tungsten alloy and the mold, and reducing damage to the mold and the niobium-tungsten alloy workpiece.

[0016] 4. During the cyanide-free electroplating copper treatment, the copper thin film wraps around the surface of the niobium-tungsten alloy workpiece, avoiding oxidation of the niobium-tungsten alloy workpiece during heating or extrusion.

[0017] 5. Compared with the existing glass lubricant, using the copper stripping solution can easily remove the copper thin film attached to the surface of the niobium-tungsten alloy workpiece without causing damage to the niobium-tungsten alloy workpiece, and the operation is simple. Specific Embodiment

[0018] The present invention will be further described in conjunction with specific embodiments.

[0019] This embodiment provides a lubrication method for plastic forming of niobium-tungsten alloy. The lubrication method includes the following steps: S1: Perform cyanide-free electroplating of copper on the niobium-tungsten alloy workpiece; S2: Extrude the niobium-tungsten alloy workpiece that has completed the cyanide-free electroplating of copper. Use an oil-based lubricant for lubrication during extrusion. The mass fraction ratio of this oil-based lubricant is: 68% oleic acid, 16% graphite, and 16% molybdenum disulfide; S3: Perform electroplating copper stripping on the niobium-tungsten alloy that has completed extrusion plastic forming.

[0020] This embodiment uses cyanide-free electroplating copper technology to electroplate a copper thin film on the surface of the niobium-tungsten alloy workpiece. An oil-based lubricant is used for lubrication during the extrusion plastic forming process. This oil-based lubricant is made of oleic acid added with graphite and molybdenum disulfide. Among them, the mass fraction ratios of oleic acid, graphite, and molybdenum disulfide are 68%, 16%, and 16% respectively, which can ensure continuous and stable lubrication of the niobium-tungsten alloy workpiece during extrusion.

[0021] Compared with using means such as brushes to apply conventional lubricants on the surface of the niobium-tungsten alloy workpiece, cyanide-free electroplating copper technology can uniformly deposit a copper thin film on the surface of workpieces with any shape. During extrusion, it can deform with the plastic forming of the niobium-tungsten alloy. There is always a copper thin film attached to the surface of the niobium-tungsten alloy workpiece, and it will not be extruded from the mold like conventional lubricants under the high contact load during the extrusion process and lose the lubrication effect. Cooperating with the oil-based lubricant for lubrication effectively improves the lubrication effect and the quality of the niobium-tungsten alloy finished product.

[0022] The cyanide-free electroplating copper treatment adopted in this embodiment is more environmentally friendly than traditional electroplating processes. At the same time, due to the improvement of the quality of plastic forming, the rejection rate and rework rate are also reduced, further improving the overall economy.

[0023] Furthermore, in steps S1 and S3, an electroplating device is used. The electroplating device is provided with an electroplating tank for containing electroplating solution. An anode and a cathode are provided in the electroplating tank. Among them, the electroplating tank is made of corrosion-resistant material. The anode is connected to the positive pole of the DC power supply, and the cathode is connected to the negative pole of the DC power supply.

[0024] The cyanide-free electroplating copper treatment in step S1 includes the following steps: S11: Degreasing: Immerse the niobium-tungsten alloy workpiece in an alkaline solution at 60°C. The ratio of this alkaline solution includes: 80 g / L sodium hydroxide, 30 g / L trisodium phosphate, 30 g / L sodium carbonate, and 1 g / L sodium silicate. Stop degreasing when the surface of the niobium-tungsten alloy workpiece presents a uniform metallic color; S12: Rinsing: Rinse the degreased niobium-tungsten alloy workpiece in clean water at 20°C to remove the alkaline solution on the surface of the niobium-tungsten alloy workpiece.

[0025] S13: Pickling: Immerse the rinsed niobium tungsten alloy workpiece in a 20°C pickling solution for 1-2 minutes to remove oxides and residual grease on the surface of the niobium tungsten alloy workpiece and expose the active metal on the surface of the niobium tungsten alloy workpiece. The mass fraction ratio of the pickling solution is: 10% hydrofluoric acid, 40% nitric acid and 50% distilled water; S14: Ultrasonic cleaning: immerse the pickled niobium-tungsten alloy workpiece in clean water at 50°C and use an ultrasonic cleaning machine to perform ultrasonic cleaning on the niobium-tungsten alloy workpiece for 1 to 2 minutes; S15: Copper electroplating: The electroplating solution is a cyanide-free electroplating solution, the anode is a pure copper plate, and the cathode is a niobium-tungsten alloy workpiece that has been degreased, rinsed, pickled and ultrasonically cleaned. The parts of the niobium-tungsten alloy workpiece immersed in the cyanide-free electroplating solution are bound and connected with pure titanium wire and then subjected to copper electroplating.

[0026] This embodiment effectively removes oil, oxides and other impurities on the surface of the niobium tungsten alloy workpiece through pretreatment steps such as degreasing, rinsing, pickling and ultrasonic cleaning, providing a clean substrate with appropriate roughness for electroplating copper, which helps to closely bond the electroplated copper layer with the workpiece surface and improve the adhesion and uniformity of the electroplated copper layer.

[0027] This embodiment uses pure titanium wire to bind and connect the niobium tungsten alloy workpieces and then electroplating copper to ensure uniform distribution of current during the electroplating process and improve the quality of electroplated copper. The copper film has good ductility and lubricity, and can effectively reduce the friction resistance between the mold and the niobium tungsten alloy workpiece with an oil-based lubricant, reduce the forming force, make the plastic forming process smoother, protect the surface of the niobium tungsten alloy workpiece from damage, and improve the quality after forming.

[0028] Furthermore, the purity of the sodium hydroxide, trisodium phosphate and sodium carbonate in step S11 are all analytically pure, and the purity of the hydrofluoric acid and nitric acid in step S13 are all analytically pure, which can effectively improve the quality and performance of the copper film and enhance the adhesion and uniformity of the copper film on the niobium tungsten alloy workpiece.

[0029] Furthermore, in step S15, the distance between the anode and the cathode is 50-60 mm, the anode area is twice the cathode area, and the current density is 1.3-1.5 A / dm 3 .

[0030] In this embodiment, the distance between the anode and the cathode is 50 - 60 mm, which can ensure that copper ions effectively migrate towards the niobium-tungsten alloy workpiece under the action of the electric field, and are reduced and deposited on its surface to form a uniform copper thin film. The anode area is twice that of the cathode area, which can provide more copper ion sources and accelerate the electroplating speed. The current density is controlled at 1.3 - 1.5 A / dm 3 , which helps to control the reduction rate of copper ions during electroplating and ensure the uniform distribution of the thickness of the copper thin film.

[0031] Specifically, the electroplating copper stripping treatment in step S3 is as follows: the electroplating solution is a copper stripping solution, the temperature of the copper stripping solution is 20 °C, the anode is the niobium-tungsten alloy workpiece that has completed the electroplating copper treatment and undergone extrusion plastic forming, the cathode is a stainless steel plate, and the niobium-tungsten alloy workpiece is tied and connected with pure titanium wire and then completely immersed in the copper stripping solution for electroplating copper stripping treatment.

[0032] In this embodiment, the niobium-tungsten alloy workpiece that has completed the electroplating copper treatment and undergone extrusion plastic forming is tied and connected with pure titanium wire and then completely immersed in the copper stripping solution, which can ensure full contact between the copper coating and the copper stripping solution, thereby achieving efficient copper stripping. Using a stainless steel plate as the cathode can avoid corrosion or dissolution of the cathode during copper stripping, thus protecting the purity and stability of the copper stripping solution and being more environmentally friendly.

[0033] Furthermore, the formulation of the copper stripping solution includes: 80 g / L ammonium nitrate and 30 g / L sodium citrate. Using sodium hydroxide to adjust the pH value of the copper stripping solution to be between 8 and 10 can effectively improve the copper stripping efficiency of the niobium-tungsten alloy workpiece.

[0034] Furthermore, the purity of the ammonium nitrate is analytical pure. High-purity ammonium nitrate can more effectively promote the electrochemical dissolution of the copper layer, thereby improving the copper stripping efficiency.

[0035] Furthermore, the distance between the anode and the cathode is 50 - 60 mm, and the current density is 2 - 3 A / dm 3 , which helps to improve the copper stripping efficiency of the niobium-tungsten alloy workpiece.

[0036] The above are only the preferred embodiments of the present invention, and do not limit the design of this case. All equivalent changes made according to the key design of this case fall within the protection scope of this case.

Claims

1. A lubrication method for plastic forming of niobium-tungsten alloy, characterized in that: The lubrication method includes the following steps: S1: Perform cyanide-free electroplating copper treatment on the niobium-tungsten alloy workpiece; S2: Extrude the niobium-tungsten alloy workpiece that has completed the cyanide-free electroplating copper treatment. When extruding, use an oil-based lubricant for lubrication. The mass fraction ratio of this oil-based lubricant is: 68% oleic acid, 16% graphite, and 16% molybdenum disulfide; S3: Perform electroplating copper stripping treatment on the niobium-tungsten alloy that has completed extrusion plastic forming.

2. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 1, characterized in that: In steps S1 and S3, an electroplating device is used. The electroplating device is provided with an electroplating tank for containing electroplating solution, and an anode and a cathode are provided in the electroplating tank; The cyanide-free electroplating copper treatment in step S1 includes the following steps: S11: Degreasing: Immerse the niobium-tungsten alloy workpiece in an alkaline solution at 60°C. The ratio of this alkaline solution includes: 80 g / L sodium hydroxide, 30 g / L trisodium phosphate, 30 g / L sodium carbonate, and 1 g / L sodium silicate. Stop degreasing when the surface of the niobium-tungsten alloy workpiece shows a uniform metallic color; S12: Rinsing: Rinse the degreased niobium-tungsten alloy workpiece in clean water at 20°C; S13: Pickling: Immerse the rinsed niobium-tungsten alloy workpiece in a pickling solution at 20°C. The pickling time is 1 - 2 min. The mass fraction ratio of this pickling solution is: 10% hydrofluoric acid, 40% nitric acid, and 50% distilled water; S14: Ultrasonic cleaning: Immerse the pickled niobium-tungsten alloy workpiece in clean water at 50°C, and use an ultrasonic cleaning machine to perform ultrasonic cleaning on the niobium-tungsten alloy workpiece. The cleaning time is 1 - 2 min; S15: Electroplating copper: The electroplating solution is a cyanide-free electroplating solution. The anode is a pure copper plate, and the cathode is the niobium-tungsten alloy workpiece that has undergone degreasing, rinsing, pickling, and ultrasonic cleaning. The part of the niobium-tungsten alloy workpiece immersed in the cyanide-free electroplating solution is tied and connected with pure titanium wire and then electroplating copper treatment is carried out.

3. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 2, characterized in that: The purities of sodium hydroxide, trisodium phosphate, and sodium carbonate in step S11 are all analytical pure, and the purities of hydrofluoric acid and nitric acid in step S13 are all analytical pure.

4. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 2, characterized in that: In the step S15, the distance between the anode and the cathode is 50 to 60 mm, the anode area is twice the cathode area, and the current density is 1.3 to 1.5 A / dm 3 .

5. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 2, characterized in that: The electroplating copper stripping treatment in step S3 is: The electroplating solution is a copper stripping solution. The temperature of the copper stripping solution is 20°C. The anode is the niobium-tungsten alloy workpiece that has completed electroplating copper treatment and undergone extrusion plastic forming, and the cathode is a stainless steel plate. The niobium-tungsten alloy workpiece is tied and connected with pure titanium wire and then completely immersed in the copper stripping solution for electroplating copper stripping treatment.

6. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 5, characterized in that: The ratio of the copper stripping solution includes: 80 g / L ammonium nitrate and 30 g / L sodium citrate. Use sodium hydroxide to adjust the pH value of the copper stripping solution to be between 8 and 10.

7. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 6, characterized in that: The purity of the ammonium nitrate is analytical pure.

8. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 5, characterized in that: The distance between the anode and the cathode is 50 to 60 mm, and the current density is 2 to 3 A / dm 3 .