Method for etching nickel-based alloys in an acidic high-iron salt bath

Abstract

The application provides a nickel-based alloy acid high-iron salt etching method, solves the defects of the original nickel-based alloy etching, improves the consistency of the surface state of the part, improves the adhesion between the plating layer and the substrate, and thus improves the quality and reliability of the product, the solution is stable, and the process control is easy. The plating layer has good adhesion, short etching time, high efficiency, small harm to human body, small environmental pollution, easy implementation, and has great application value.

Description

Technical Field

[0001] This invention belongs to the field of surface treatment technology, specifically relating to a method for etching nickel-based alloys with acidic ferric salts. Background Technology

[0002] Nickel-based alloys possess high strength, high thermal toughness, high corrosion resistance, and resistance to oxidation corrosion, stress corrosion cracking, and corrosion fatigue. They can be categorized into nickel-based heat-resistant alloys, nickel-based corrosion-resistant alloys, nickel-based wear-resistant alloys, nickel-based precision alloys, and nickel-based shape memory alloys, and are widely used in aerospace, nuclear power, marine engineering, petrochemicals, precision sensors, electromechanical equipment, environmental protection, and biomedicine industries. To improve certain special properties of nickel-based alloy surfaces, such as weldability, anti-adhesion, wear resistance, high-temperature oxidation resistance, and adhesion, electroplating or chemical plating with Ag, Sn, Ni, Cr, Co, Rh, Pt, Au, Re, and Cu-Sn alloys is required. However, due to the presence of numerous alloying elements such as Cu, Cr, Mo, W, Co, Al, Ti, B, Zr, Nb, and In in nickel-based alloys, they are easily passivated, resulting in the natural formation of an extremely thin and robust passivation film on the surface, which remains passivated under normal conditions. This passivation film has strong corrosion resistance, making electroplating or electroless plating of nickel-based alloys very difficult. If the passivation film is not completely removed, a good coating that is firmly bonded to the substrate cannot be obtained. Therefore, the key to electroplating or electroless plating of nickel-based alloy parts lies in whether the natural passivation film can be effectively removed during pre-plating treatment. This is a prerequisite for ensuring good adhesion between the coating and the substrate.

[0003] The electroplating or electroless plating process for nickel-based alloys mainly consists of degreasing, etching, pre-plating, and electroplating or electroless plating. Currently, the etching process before electroplating or electroless plating of nickel-based alloys usually uses chemical etching or anodic etching with a strong acid solution containing high concentrations of nitric acid and hydrofluoric acid. Nitric acid produces a large amount of toxic "yellow fumes" during etching, while hydrofluoric acid is highly toxic and volatile. The solution is unstable, the process is difficult to control, the etching effect is poor (inconsistent surface condition of parts), the etching time is long and the efficiency is low, and it is highly toxic to the human body and causes significant environmental pollution. After electroplating or electroless plating, the coating adhesion is poor (often peeling, blistering, and flaking occur). In order to address these problems, it is essential to research and develop new etching methods that can improve the coating adhesion while achieving solution stability, short etching time, and low toxicity to the human body and low environmental pollution. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a method for etching nickel-based alloys with acidic ferric salts, which overcomes the shortcomings of existing nickel-based alloy etching methods, improves the consistency of the surface condition of parts, enhances the adhesion between the coating and the substrate, thereby improving product quality and reliability. The solution is stable, the process is easy to control, the coating adhesion is good, the etching time is short and efficient, it has low toxicity to humans and low environmental pollution, is easy to implement, and has significant application value.

[0005] The technical solution adopted in this invention is a method for etching nickel-based alloys with acidic ferric salts, comprising the following steps:

[0006] 1) Pre-cleaning: Clean the surface of the nickel-based alloy parts with gasoline or other solvents;

[0007] 2) Mounting: Use pure copper wire or clamps to mount nickel-based alloy parts;

[0008] 3) Alkaline degreasing: Prepare the degreasing solution according to the following composition: sodium hydroxide (NaOH): 35-45 g / L, trisodium phosphate (Na3PO4·12H2O): 20-30 g / L, sodium carbonate (Na2CO3·10H2O): 20-30 g / L, sodium silicate (Na2SiO3): 3-5 g / L, and immerse the dried nickel-based alloy parts in the degreasing solution for electrochemical or chemical degreasing;

[0009] 4) Etching: Prepare the etching solution according to the following composition: ferric chloride (FeCl3·6H2O) 250~330g / L, hydrochloric acid (HCl) with a density of 1.10g / mL~1.25g / mL 126~143mL / L, balance: deionized water. Immerse the degreased nickel-based alloy parts in the etching solution to etch the passivation film on their surface.

[0010] 5) Pre-plating nickel: The nickel-based alloy parts after etching are pre-plated with nickel in a prepared electroplating solution. The specific components of the electroplating solution are as follows: nickel chloride (NiCl2·6H2O) 160~200g / L, hydrochloric acid (HCl) with a density of 1.10g / mL~1.25g / mL 100~134mL / L.

[0011] 6) Electroplating or electroless plating of silver, tin, nickel, chromium, cobalt, rhodium, palladium, gold, rhenium, or copper-tin alloy coatings can be performed on the nickel-based alloy parts after pre-plating with nickel.

[0012] In step 3) above, the temperature during electrochemical degreasing is 60–80°C, and the current density is 3–10 A / dm³. 2 The processing time is 10-20 minutes for the cathode and 5-10 minutes for the anode. The electrode material is steel plate or nickel-plated steel plate.

[0013] In step 3) above, the temperature during chemical degreasing is 70-80℃ and the degreasing time is 20-30 minutes.

[0014] In step 5) above, the temperature for pre-plating nickel on the nickel-based alloy parts is 18–30°C, and the current density is 5–8 A / dm³. 2 The time is 2 to 5 minutes, and the electrode material is NY1 or NY2.

[0015] Advantages of this invention compared to existing technologies:

[0016] 1. This technical solution solves the shortcomings of the original nickel-based alloy etching, improves the consistency of the surface condition of the parts, and improves the adhesion between the coating and the substrate, thereby improving the quality and reliability of the product.

[0017] 2. The degreasing solution and etching solution of this technical solution are stable, the process is easy to control, the coating has good adhesion, and the etching time is short and the efficiency is high.

[0018] 3. The acidic ferrous salt etching solution solves the problem of generating a large amount of toxic "yellow smoke" during the etching process, which is highly toxic to the human body and causes great environmental pollution. The process is simple and easy to operate. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] Example 1

[0022] A method for etching nickel-based alloys with acidic ferric salts includes the following steps:

[0023] 1) Pre-cleaning: Clean the surface of the nickel-based alloy parts with gasoline or other solvents, and let them air dry at room temperature for 30 to 60 minutes;

[0024] 2) Mounting: Use pure copper wire or clamps to mount nickel-based alloy parts;

[0025] 3) Alkaline degreasing: Prepare the degreasing solution according to the following composition: sodium hydroxide (NaOH): 35g / L, trisodium phosphate (Na3PO4·12H2O): 20g / L, sodium carbonate (Na2CO3·10H2O): 20g / L, sodium silicate (Na2SiO3): 3g / L, and immerse the dried nickel-based alloy parts in the degreasing solution for electrochemical or chemical degreasing;

[0026] The electrochemical degreasing process is carried out at a temperature of 60°C and a current density of 4 A / dm³. 2 The processing time is 10 minutes for the cathode and 5 minutes for the anode, and the electrode material is steel plate or nickel-plated steel plate; or the temperature of the chemical degreasing is 70°C and the degreasing time is 20 minutes.

[0027] 4) Etching: Prepare the etching solution according to the following composition: ferric chloride (FeCl3·6H2O) 250g / L, hydrochloric acid (HCl, ρ about 1.19g / mL): 126mL / L, balance: deionized water. Put the degreased nickel-based alloy parts into the etching solution to etch the passivation film on their surface.

[0028] 5) Pre-plating with nickel: The etched nickel-based alloy parts are pre-plated with nickel in a prepared electroplating solution. The specific components of the electroplating solution are as follows: 160 g / L nickel chloride (NiCl2·6H2O) and 100 mL / L hydrochloric acid (HCl) with a density of 1.10 g / mL. The temperature for pre-plating the nickel-based alloy parts is 18°C, and the current density is 5 A / dm³. 2 The time was 2 minutes, and the electrode material was NY1 or NY2.

[0029] 6) Electroplating or electroless plating of silver, tin, nickel, chromium, cobalt, rhodium, palladium, gold, rhenium, or copper-tin alloy coatings can be performed on the nickel-based alloy parts after pre-plating with nickel.

[0030] Example 2

[0031] A method for etching nickel-based alloys with acidic ferric salts includes the following steps:

[0032] 1) Pre-cleaning: Clean the surface of the nickel-based alloy parts with gasoline or other solvents, and let them air dry at room temperature for 30 to 60 minutes;

[0033] 2) Mounting: Use pure copper wire or clamps to mount nickel-based alloy parts;

[0034] 3) Alkaline degreasing: Prepare the degreasing solution according to the following composition: sodium hydroxide (NaOH): 40g / L, trisodium phosphate (Na3PO4·12H2O): 25g / L, sodium carbonate (Na2CO3·10H2O): 25g / L, sodium silicate (Na2SiO3): 4g / L, and immerse the dried nickel-based alloy parts in the degreasing solution for electrochemical or chemical degreasing;

[0035] The electrochemical degreasing process is carried out at a temperature of 70°C and a current density of 6 A / dm³. 2 The processing time is 15 minutes for the cathode and 8 minutes for the anode, and the electrode material is steel plate or nickel-plated steel plate; or the temperature of the chemical degreasing is 75°C and the degreasing time is 25 minutes.

[0036] 4) Etching: Prepare the etching solution according to the following composition: 280 g / L ferric chloride (FeCl3·6H2O), 135 mL / L hydrochloric acid (HCl) with a density of 1.19 g / mL, and the balance: deionized water. Place the degreased nickel-based alloy parts into the etching solution to etch the passivation film on their surface.

[0037] 5) Pre-plating with nickel: The etched nickel-based alloy parts are pre-plated with nickel in a prepared electroplating solution. The specific components of the electroplating solution are as follows: nickel chloride (NiCl2·6H2O) 160-200 g / L, hydrochloric acid (HCl) with a density of 1.19 g / mL 120 mL / L; the temperature for pre-plating the nickel-based alloy parts is 18-30℃, and the current density is 5-8 A / dm³. 2 The time is 2-5 minutes, and the electrode material is NY1 or NY2.

[0038] 6) Electroplating or electroless plating of silver, tin, nickel, chromium, cobalt, rhodium, palladium, gold, rhenium, or copper-tin alloy coatings can be performed on the nickel-based alloy parts after pre-plating with nickel.

[0039] Example 3

[0040] A method for etching nickel-based alloys with acidic ferric salts includes the following steps:

[0041] 1) Pre-cleaning: Clean the surface of the nickel-based alloy parts with gasoline or other solvents, and let them air dry at room temperature for 30 to 60 minutes;

[0042] 2) Mounting: Use pure copper wire or clamps to mount nickel-based alloy parts;

[0043] 3) Alkaline degreasing: Prepare the degreasing solution according to the following composition: sodium hydroxide (NaOH): 45g / L, trisodium phosphate (Na3PO4·12H2O): 30g / L, sodium carbonate (Na2CO3·10H2O): 30g / L, sodium silicate (Na2SiO3): 5g / L, and immerse the dried nickel-based alloy parts in the degreasing solution for electrochemical or chemical degreasing;

[0044] The electrochemical degreasing process is carried out at a temperature of 80°C and a current density of 10 A / dm³. 2 The processing time is 20 minutes for the cathode and 10 minutes for the anode, and the electrode material is steel plate or nickel-plated steel plate; or the temperature of the chemical degreasing is 80°C and the degreasing time is 30 minutes.

[0045] 4) Etching: Prepare the etching solution according to the following composition: 330 g / L ferric chloride (FeCl3·6H2O), 143 mL / L hydrochloric acid (HCl) with a density of 1.25 g / mL, and the balance: deionized water. Place the degreased nickel-based alloy parts into the etching solution to etch the passivation film on their surface.

[0046] Preparation of etching solution: Taking the preparation of 1L solution as an example, first add 400mL of deionized water to a plastic, fiberglass or ceramic tank, then add 143mL of hydrochloric acid, then add 330g of ferric chloride to the above solution, stir thoroughly to completely dissolve the ferric chloride, and finally add deionized water to 1L.

[0047] The roles of each component in the etching solution:

[0048] Ferric chloride: Ferric chloride hexahydrate is an orange-yellow crystal, readily soluble in water, forming a strong acid-weak base salt. It is the salt with the strongest acidity in aqueous solution. 3+ It has strong oxidizing and corrosive properties, and generally undergoes the M+Fe reaction. 3+ =M 2+或3+ +Fe 3+ The redox reaction can oxidize the main elements Cu, Fe, Cr, Mo, Ti, W, etc. on the surface of nickel-based alloys, producing a pitting corrosion effect, destroying the passivation film structure on the surface of nickel-based alloys, and promoting their dissolution.

[0049] Hydrochloric acid: At room temperature, hydrochloric acid has a strong etching ability on metal oxides, but its dissolution of base metals such as steel is relatively slow. It plays two main roles in etching solutions: firstly, to provide sufficient H₂... + The first step is to generate hydrogen depolarization corrosion, which accelerates the complete dissolution of the passivation film on the surface of nickel-based alloys; the second step is to simulate the hydrolysis of ferric chloride to generate colloidal Fe(OH)3, which ensures the stability of the solution.

[0050] 5) Pre-plating with nickel: The etched nickel-based alloy parts are pre-plated with nickel in a prepared electroplating solution. The specific components of the electroplating solution are as follows: 200 g / L nickel chloride (NiCl2·6H2O) and 134 mL / L hydrochloric acid (HCl) with a density of 1.25 g / mL. The temperature for pre-plating the nickel-based alloy parts is 30°C, and the current density is 8 A / dm³. 2 The time is 5 minutes, and the electrode material is NY1 or NY2.

[0051] 6) Electroplating or electroless plating of silver, tin, nickel, chromium, cobalt, rhodium, palladium, gold, rhenium, or copper-tin alloy coatings can be performed on the nickel-based alloy parts after pre-plating with nickel.

[0052] This technical solution addresses the shortcomings of traditional nickel-based alloy etching, improving the consistency of part surface conditions and enhancing the adhesion between the coating and the substrate, thereby improving product quality and reliability. The degreasing solution and etching solution are stable, the process is easy to control, the coating adhesion is good, and the etching time is short and efficient. Acidic ferric salt etching solves the problem of generating large amounts of toxic "yellow fumes" during the etching process, which are highly harmful to humans and cause significant environmental pollution. The process is simple and easy to operate.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for etching nickel-based alloys with acidic ferric salts, characterized in that... Includes the following steps: 1) Pre-cleaning: Clean the surface of the nickel-based alloy parts with gasoline or other solvents, and let them air dry at room temperature for 30-60 minutes; 2) Mounting: Use pure copper wire or clamps to mount nickel-based alloy parts; 3) Alkaline degreasing: Prepare the degreasing solution according to the following composition: sodium hydroxide (NaOH): 35-45 g / L, trisodium phosphate (Na3PO4•12H2O): 20-30 g / L, sodium carbonate (Na2CO3•10H2O): 20-30 g / L, sodium silicate (Na2SiO3): 3-5 g / L, and immerse the dried nickel-based alloy parts in the degreasing solution for electrochemical or chemical degreasing; The electrochemical oil removal process is carried out at a temperature of 60–80°C and a current density of 3–10 A / dm³. 2 The processing time is 10-20 min for the cathode first, followed by 5-10 min for the anode. The electrode material is steel plate or nickel-plated steel plate. 4) Etching: Prepare the etching solution according to the following composition: ferric chloride (FeCl3•6H2O) 250~330g / L, hydrochloric acid (HCl) with a density of 1.10g / mL~1.25g / mL 126~143 mL / L, balance: deionized water. Immerse the degreased nickel-based alloy parts in the etching solution to etch the passivation film on their surface. 5) Pre-plating nickel: The nickel-based alloy parts after etching are pre-plated with nickel in a prepared electroplating solution. The specific components of the electroplating solution are as follows: nickel chloride (NiCl2•6H2O) 160~200g / L, hydrochloric acid (HCl) with a density of 1.10g / mL~1.25g / mL 100~134 mL / L; 6) Electroplating or electroless plating of silver, tin, nickel, chromium, cobalt, rhodium, palladium, gold, rhenium, or copper-tin alloy coatings can be performed on nickel-based alloy parts that have been pre-plated with nickel.

2. The method for etching nickel-based alloys with acidic ferric salts according to claim 1, characterized in that: In step 3) above, the temperature during chemical degreasing is 70-80℃ and the degreasing time is 20-30 minutes.

3. The method for etching nickel-based alloys with acidic ferric salts according to claim 1, characterized in that: In step 5) above, the temperature for pre-plating nickel on the nickel-based alloy parts is 18–30°C, and the current density is 5–8 A / dm³. 2 The time is 2 to 5 minutes, and the electrode material is NY1 or NY2.