A lubrication method for plastic forming of niobium-tungsten alloy

Abstract

The present invention discloses a lubrication method for the plastic forming of a niobium-tungsten alloy, relating to the technical field of alloy processing lubrication. The lubrication method comprises the following steps: S1: subjecting a niobium-tungsten alloy workpiece to cyanide-free copper electroplating; S2: extruding the niobium-tungsten alloy workpiece that has undergone cyanide-free copper electroplating, lubricating it with an oil-based lubricant during extrusion, wherein the oil-based lubricant comprises 68% oleic acid, 16% graphite, and 16% molybdenum disulfide by mass fraction; and S3: subjecting the extruded niobium-tungsten alloy to an electroplating copper stripping treatment. The present invention can provide continuous and stable lubrication under high contact loads during the plastic forming process, effectively reducing contact friction between the niobium-tungsten alloy workpiece and the die, minimizing damage to the die and the niobium-tungsten alloy workpiece, improving the quality of the plastic forming, and is simple to operate.

Description

Technical Field

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

[0002] Due to its high yield strength and high work hardening rate, niobium-tungsten alloys face significant contact loads between the workpiece and the die during cold forming, resulting in high forming forces and difficulty in forming. Although lubrication can reduce friction and forming forces, the chemical inertness of niobium-tungsten alloys limits the use of conventional lubrication treatments (such as phosphating and oxalate-fluoride treatments). Furthermore, conventional lubricants (such as graphite lubricant powders or lubricants such as rapeseed oil and chlorinated paraffin oil) are easily squeezed out of the die under high loads, making it difficult to ensure lubrication during the extrusion process.

[0003] While high-temperature forming (300-500°C) can reduce forming forces compared to cold forming, the niobium-tungsten alloy surface oxidizes at 300°C, and oxidative powdering occurs above 500°C. To avoid this problem, existing treatment methods include lubrication with glass lubricants, which can transform into a high-viscosity solution within a certain temperature range to encapsulate the niobium-tungsten alloy workpiece and isolate it from the air. However, it is difficult to control the thickness of the lubricating film with glass lubricants, and they need to be applied before each extrusion. They cannot be pre-fabricated on the surface of the niobium-tungsten alloy workpiece, making the process more complicated. Furthermore, the glass lubricant easily adheres to the niobium-tungsten alloy workpiece and the mold surface during extrusion, making removal more difficult and prone to damage. Summary of the Invention

[0004] 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 mold, and improve the quality of plastic forming.

[0005] To achieve the above objectives, the core concept of the present invention is to electroplate a copper film onto the surface of the niobium-tungsten alloy workpiece before denaturation using a cyanide-free electroplating technique. During electroplating, after activation treatment, etched micro-pits are generated on the surface of the niobium-tungsten alloy substrate. The copper element of the copper film is embedded in these etched micro-pits and mechanically embedded with the niobium-tungsten alloy substrate, thereby enhancing the bond between the copper film and the niobium-tungsten alloy substrate. Because the copper film has good ductility, it can denature and flow along with the niobium-tungsten alloy workpiece, ensuring continuous and stable lubrication during the extrusion process. In addition, the use of oleic acid with added graphite and molybdenum disulfide for lubrication during extrusion can further enhance the lubrication effect of the niobium-tungsten alloy workpiece during extrusion.

[0006] 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:

[0007] S1: subjecting the niobium-tungsten alloy workpiece to cyanide-free electroplating copper;

[0008] S2: Extruding the niobium-tungsten alloy workpiece after the cyanide-free copper electroplating treatment, and lubricating it with an oil-based lubricant. The mass fraction of the oil-based lubricant is: 68% oleic acid, 16% graphite, and 16% molybdenum disulfide;

[0009] S3: The niobium-tungsten alloy that has completed the extrusion plastic forming is subjected to electroplating copper stripping treatment.

[0010] Preferably, an electroplating device is used in step S1 and step S3, wherein the electroplating device is provided with an electroplating tank for containing an electroplating solution, and an anode and a cathode are provided in the electroplating tank;

[0011] The cyanide-free copper electroplating process in step S1 comprises the following steps:

[0012] S11: Degreasing: Immerse the niobium tungsten alloy workpiece in an alkaline solution at 60°C. The alkaline solution contains 80g / L sodium hydroxide, 30g / L trisodium phosphate, 30g / L sodium carbonate, and 1g / L sodium silicate. Stop degreasing when the surface of the niobium tungsten alloy workpiece shows a uniform metallic color.

[0013] S12: Rinse: Rinse the degreased niobium-tungsten alloy workpiece in clean water at 20°C;

[0014] S13: Pickling: Immerse the rinsed niobium-tungsten alloy workpiece in a 20°C pickling solution for 1-2 minutes. The pickling solution contains 10% hydrofluoric acid, 40% nitric acid, and 50% distilled water.

[0015] 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.

[0016] 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 tied and connected using pure titanium wire and then subjected to copper electroplating.

[0017] In a preferred embodiment, 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.

[0018] Preferably, 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 .

[0019] In a preferred embodiment, 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 the copper plating treatment and undergone extrusion plastic forming, the cathode is a stainless steel plate, and the niobium-tungsten alloy workpiece is bundled and connected with pure titanium wire and then completely immersed in the copper stripping solution for electroplating copper stripping treatment.

[0020] In a preferred embodiment, the copper stripping solution comprises 80 g / L ammonium nitrate and 30 g / L sodium citrate, and the pH value of the copper stripping solution is adjusted to between 8 and 10 using sodium hydroxide.

[0021] Preferably, the purity of the ammonium nitrate is analytically pure.

[0022] In the preferred embodiment, the distance between the anode and cathode of the electroplating copper stripping treatment in step S3 is 50-60 mm, and the current density is 2-3 A / dm 3 .

[0023] After adopting the above solution, the beneficial effects of the present invention are:

[0024] 1. Use cyanide-free electroplating technology to evenly electroplate a layer of copper film on the surface of the niobium tungsten alloy workpiece. The copper 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 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 die, and improving the quality of plastic forming.

[0025] 2. After activation, etched micro-pits form on the surface of the niobium-tungsten alloy workpiece. During cyanide-free copper plating, copper elements embed into these etched micro-pits, creating a mechanical inlay with the niobium-tungsten alloy workpiece. This strengthens the bond between the copper film and the niobium-tungsten alloy workpiece. Unlike conventional lubricants, this film will not be squeezed out of the die and lose its lubricating effect under the high contact loads of the extrusion process. Furthermore, during the extrusion plastic forming process, the metal of the niobium-tungsten alloy workpiece will flow, and the copper film on the surface of the niobium-tungsten alloy workpiece will deform and flow accordingly. This ensures that the copper film is always attached to the surface of the niobium-tungsten alloy workpiece during the extrusion process, effectively improving the lubrication effect.

[0026] 3. The hardness of the copper film is very low. During the extrusion process, the copper 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.

[0027] 4. During the cyanide-free copper electroplating process, the copper film is wrapped on the surface of the niobium-tungsten alloy workpiece to prevent the niobium-tungsten alloy workpiece from being oxidized during heating or extrusion.

[0028] 5. Compared with the existing glass lubricant, the copper stripping liquid can easily remove the copper film attached to the surface of the niobium tungsten alloy workpiece without causing damage to the niobium tungsten alloy workpiece and is easy to operate. DETAILED DESCRIPTION

[0029] The present invention will now be further described with reference to specific embodiments.

[0030] This embodiment provides a lubrication method for plastic forming of niobium-tungsten alloy, the lubrication method comprising the following steps:

[0031] S1: subjecting the niobium-tungsten alloy workpiece to cyanide-free electroplating copper;

[0032] S2: Extruding the niobium-tungsten alloy workpiece after the cyanide-free copper electroplating treatment, and lubricating it with an oil-based lubricant. The mass fraction of the oil-based lubricant is: 68% oleic acid, 16% graphite, and 16% molybdenum disulfide;

[0033] S3: The niobium-tungsten alloy that has completed the extrusion plastic forming is subjected to electroplating copper stripping treatment.

[0034] In this embodiment, a copper film is electroplated on the surface of the niobium tungsten alloy workpiece using a cyanide-free copper electroplating technology. An oil-based lubricant is used for lubrication during the extrusion molding process. The oil-based lubricant is made of oleic acid to which graphite and molybdenum disulfide are added. The mass fractions of oleic acid, graphite, and molybdenum disulfide are 68%, 16%, and 16%, respectively. This can ensure continuous and stable lubrication of the niobium tungsten alloy workpiece during the extrusion process.

[0035] Compared with applying conventional lubricants on the surface of niobium tungsten alloy workpieces using brushes and other means, cyanide-free copper electroplating technology can evenly deposit a layer of copper film on the surface of workpieces of any shape. During the extrusion process, it can deform along with the plastic forming of niobium tungsten alloy. There is always a copper film attached to the surface of the niobium tungsten alloy workpiece. Under the high contact load of the extrusion process, it will not be squeezed out of the mold like conventional lubricants and lose its lubricating effect. It is lubricated in combination with oil-based lubricants, which effectively improves the lubrication effect and the quality of niobium tungsten alloy products.

[0036] The cyanide-free copper electroplating process used in this embodiment is more environmentally friendly than the traditional electroplating process. At the same time, since the quality of plastic forming is improved, the scrap rate and rework rate are also reduced, further improving the overall economic efficiency.

[0037] Furthermore, an electroplating device is used in step S1 and step S3, and the electroplating device is provided with an electroplating tank, which is used to hold the electroplating liquid, and the electroplating tank is provided with an anode and a cathode, wherein 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.

[0038] The cyanide-free copper electroplating process in step S1 comprises the following steps:

[0039] S11: Degreasing: Immerse the niobium tungsten alloy workpiece in an alkaline solution at 60°C. The alkaline solution contains 80g / L sodium hydroxide, 30g / L trisodium phosphate, 30g / L sodium carbonate, and 1g / L sodium silicate. Stop degreasing when the surface of the niobium tungsten alloy workpiece shows a uniform metallic color.

[0040] 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.

[0041] 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;

[0042] 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.

[0043] 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 tied and connected using pure titanium wire and then subjected to copper electroplating.

[0044] This embodiment effectively removes oil stains, oxides, and other impurities from the surface of the niobium tungsten alloy workpiece through pretreatment steps such as degreasing, rinsing, pickling, and ultrasonic cleaning, providing a clean substrate with a suitable roughness for electroplating copper, facilitating a close bonding between the electroplated copper layer and the workpiece surface, and improving the adhesion and uniformity of the electroplated copper layer.

[0045] This embodiment utilizes copper electroplating after the niobium-tungsten alloy workpieces are bound and connected using pure titanium wire. This ensures uniform current distribution during the electroplating process, improving the quality of the plated copper. The copper film has excellent ductility and lubricity. When combined with an oil-based lubricant, it effectively reduces friction between the mold and the niobium-tungsten alloy workpiece, lowering forming forces and facilitating a smoother plastic forming process. This protects the niobium-tungsten alloy workpiece surface from damage, thereby improving the quality of the finished product.

[0046] 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.

[0047] 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 .

[0048] In this embodiment, the distance between the anode and cathode is 50-60 mm, which can ensure that copper ions effectively migrate to 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 film. The anode area is twice the cathode area, which can provide more copper ion sources and accelerate the electroplating speed. The current density is controlled at 1.3-1.5A / dm 3 , which helps control the reduction rate of copper ions during the electroplating process and ensures uniform thickness distribution of the copper film.

[0049] 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 a niobium tungsten alloy workpiece that has completed the electroplating copper treatment and undergone extrusion plastic forming, and the cathode is a stainless steel plate. The niobium tungsten alloy workpiece is bundled and connected with pure titanium wire and then completely immersed in the copper stripping solution for electroplating copper stripping treatment.

[0050] In this embodiment, niobium-tungsten alloy workpieces that have undergone copper electroplating and extrusion plastic forming are bound together with pure titanium wire and then completely immersed in a copper stripping solution. This ensures full contact between the copper coating and the solution, resulting in efficient copper stripping. Using a stainless steel plate as the cathode prevents corrosion or dissolution during the copper stripping process, thereby preserving the purity and stability of the solution and improving environmental performance.

[0051] Furthermore, the copper stripping solution comprises 80 g / L ammonium nitrate and 30 g / L sodium citrate, and the pH value of the copper stripping solution is adjusted to between 8 and 10 using sodium hydroxide, which can effectively improve the copper stripping efficiency of the niobium tungsten alloy workpiece.

[0052] Furthermore, the purity of the ammonium nitrate is analytically pure. High-purity ammonium nitrate can more effectively promote the electrochemical dissolution of the copper layer, thereby improving the copper stripping efficiency.

[0053] Furthermore, the distance between the anode and cathode of the electroplating copper stripping treatment in step S3 is 50-60 mm, and the current density is 2-3 A / dm 3 , which helps to improve the copper stripping efficiency of niobium tungsten alloy workpieces.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the design of this case. Any equivalent changes made based on the key design of this case shall fall within the scope of protection of this case.

Claims

1. A lubrication method for plastic forming of niobium-tungsten alloy, characterized by: The lubrication method comprises the following steps: S1: subjecting the niobium-tungsten alloy workpiece to cyanide-free electroplating copper; S2: Extruding the niobium-tungsten alloy workpiece after the cyanide-free copper electroplating treatment, and lubricating it with an oil-based lubricant. The mass fraction of the oil-based lubricant is: 68% oleic acid, 16% graphite, and 16% molybdenum disulfide; S3: The niobium-tungsten alloy that has completed the extrusion plastic forming is subjected to electroplating copper stripping treatment.

2. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 1, characterized in that: In step S1 and step S3, an electroplating device is used, wherein the electroplating device is provided with an electroplating tank for containing an electroplating solution, and an anode and a cathode are provided in the electroplating tank; The cyanide-free copper electroplating process in step S1 comprises the following steps: S11: Degreasing: Immerse the niobium tungsten alloy workpiece in an alkaline solution at 60°C. The alkaline solution contains 80g / L sodium hydroxide, 30g / L trisodium phosphate, 30g / L sodium carbonate, and 1g / L sodium silicate. Stop degreasing when the surface of the niobium tungsten alloy workpiece shows a uniform metallic color. S12: Rinse: Rinse the degreased niobium-tungsten alloy workpiece in clean water at 20°C; S13: Pickling: Immerse the rinsed niobium-tungsten alloy workpiece in a 20°C pickling solution for 1-2 minutes. The pickling solution contains 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 tied and connected using pure titanium wire and then subjected to copper electroplating.

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

4. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 2, wherein: 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 .

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

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

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 analytically pure.

8. The lubrication method for plastic forming of niobium-tungsten alloy according to claim 5, characterized in that: In the step S3, the distance between the anode and cathode of the electroplating copper stripping treatment is 50-60 mm, and the current density is 2-3 A / dm 3 .