A room-temperature bluing liquid suitable for alloy steel and its use method

Abstract

The present invention discloses a room-temperature bluing solution suitable for alloy steel and its use method. The chemical components and weight proportions involved in the bluing solution are as follows: 18-240g / LNaOH, 15-30g / LNaNO2, 35-50g / LNaNO3, 1-4g / LK4P2O7, 3-12% H2O2, 2-8g / LNa3PO4, 1-4g / L of complexing agent, 1-3ml / LOP-10, pH=10-14. These chemical reagents are added to water at the same time according to the ratio and stirred evenly to obtain the bluing solution. The bluing process is as follows: the surface of the alloy steel is polished until it is smooth and has no obvious scratches, then alkaline washing and degreasing are performed, the surface is cleaned, pre-oxidized by high-temperature heating, quenched and blued for a certain period of time, removed, cleaned, dried, and then saponified for a certain period of time to obtain a layer of dark blue and dense oxide film on the surface. The bluing agent provided by the present invention can be used at room temperature, has low energy consumption, is environmentally friendly and low cost, is suitable for quenching bluing of low-alloy steel, and the oxide film layer prepared using the bluing liquid has the characteristics of being smooth and dense, low porosity, good adhesion, stability, and good corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material surface treatment, and in particular to a room-temperature bluing solution suitable for alloy steel and a use method thereof. Background Art

[0002] Metal materials have become an integral part of daily life, widely used in various industries such as transportation, agriculture, and healthcare. From the earliest days of the Iron Age to the current information technology era, humanity has continuously improved the mechanical, physical, and chemical properties of metal materials. However, the corrosion of metal materials remains a major challenge and a key research focus. Statistics show that annual economic losses due to metal corrosion amount to 2-4% of the national economy. Furthermore, metal corrosion poses significant safety risks, resulting in incalculable and severe consequences. Furthermore, the corrosive fluids produced by corrosion can pollute the environment, contaminating soil and water, further threatening human health. Therefore, metal corrosion is a major issue that urgently needs to be addressed.

[0003] Fe3O4 is a ferromagnetic compound belonging to iron oxide. Due to its excellent magnetic properties, it is often used in various aspects such as magnetic fluid technology, photocatalysis, and magnetic refrigeration. In addition, Fe3O4 films are gradually attracting attention in terms of corrosion protection. Studies have found that preparing a layer of blue Fe3O4 film on the surface of steel can improve the corrosion resistance of the base material.

[0004] Common bluing and blackening processes include traditional high-temperature alkaline bluing and room-temperature acid bluing. High-temperature alkaline bluing involves immersing the metal in a concentrated alkaline solution at 130-150°C. The bluing solution primarily consists of chemicals such as NaOH, NaNO₂, NaNO₃, or KNO₃. This technique is suitable for various precision instruments and aesthetically pleasing parts, but it suffers from long processing cycles, high energy consumption, low efficiency, and operator hazards. Room-temperature acid bluing, unlike high-temperature alkaline bluing, requires no heating and can react directly at room temperature. This reduces energy consumption and increases efficiency, but it requires extremely high material pre-treatment, resulting in poor adhesion of the resulting film. Furthermore, most bluing solutions are highly toxic and pose significant health risks. Other methods include steel bluing using residual heat, hydrothermal bluing, and phosphating. These methods have long processing cycles and high costs. Therefore, developing a fast, streamlined bluing process is crucial to improving the performance of steel. Summary of the Invention

[0005] To solve the above problems, the present invention provides a room-temperature bluing solution suitable for alloy steel and a method for using the same. The present invention is achieved through the following technical solutions.

[0006] A room-temperature bluing solution suitable for alloy steel is composed of the following components: 180-240 g / L sodium hydroxide, 15-30 g / L sodium nitrite, 35-50 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L complexing agent, and 1-3 ml / L OP-10 emulsifier. The pH of the bluing solution is 10-14.

[0007] Furthermore, the complexing agent is one or more of sodium citrate, tartaric acid, gluconic acid, and thiourea.

[0008] Furthermore, the bluing solution is composed of the following components: 200-240 g / L sodium hydroxide, 20-28 g / L sodium nitrite, 35-45 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L complexing agent and 2 ml / L OP-10 emulsifier, and the pH of the bluing solution is 11-14.

[0009] Furthermore, the bluing solution is composed of the following components: 200-240 g / L sodium hydroxide, 20-28 g / L sodium nitrite, 35-45 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L complexing agent and 2 ml / L OP-10 emulsifier, and the pH of the bluing solution is 12-13.

[0010] A method for using a room-temperature bluing solution suitable for alloy steel, the method comprising the following steps:

[0011] S1. Preparation of bluing solution: Weigh the following components according to the following ratio: 20-28 g / L sodium nitrite, 35-45 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L chelating agent, and 2 ml / L OP-10 emulsifier. Add these components to a beaker in this order and mix until all components are fully dissolved. Adjust the pH to 12-13 with 200-240 g / L sodium hydroxide to obtain a bluing solution.

[0012] S2: The alloy steel used in the experiment is sequentially ground and polished, alkaline-washed for oil removal, pickled for rust removal, and high-temperature pre-oxidized. The alloy steel after high-temperature pre-oxidation is then directly placed in the bluing solution prepared in step S1 for quenching. After oxidation and bluing, the alloy steel is taken out and placed in soapy water at a temperature of 70-100°C for saponification for 5-10 minutes. The alloy steel is then taken out, washed, and dried.

[0013] Furthermore, the blueing time of the alloy steel after high-temperature pre-oxidation is 4-10 minutes.

[0014] Furthermore, the blueing time of the alloy steel after high-temperature pre-oxidation is 5 minutes.

[0015] Furthermore, the high-temperature pre-oxidation temperature of the alloy steel is 350-500°C.

[0016] Furthermore, the high-temperature pre-oxidation time of the alloy steel is 10-15 minutes.

[0017] The room-temperature bluing liquid provided by the present invention has low energy consumption and low cost, and is suitable for room-temperature bluing of alloy steel. The oxide film layer obtained by using the room-temperature bluing liquid provided by the present invention is uniform and dense, has good adhesion, good glossiness, and improved corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the description of the specific implementation methods. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 : Nyquist plots of sample and bare steel;

[0020] Figure 2 : Tafel curves of sample and bare steel. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] In this application, the composition of the alloy steel (BC550) used in the experiment is shown in the following table.

[0023] Chemical composition of steel used in research (mass fraction)%

[0024]

[0025] The present invention has the following embodiments: Example 1

[0026] (1) Prepare the following ingredients in the following proportions: 15g / L sodium nitrite, 35g / L sodium nitrate, 4g / L potassium pyrophosphate, 3% hydrogen peroxide, 2g / L sodium phosphate, 1g / L chelating agent, 1ml / L OP-10 emulsifier, and adjust the pH to 10 with 180g / L sodium hydroxide solution.

[0027] (2) Prepare 200 mL of solution according to step (1) and maintain the solution temperature at 25-30°C.

[0028] (3) After grinding and polishing, alkaline washing for oil removal, pickling for rust removal, and heating for pre-oxidation, the 13 mm × 13 mm test alloy steel is taken out and immersed in the room temperature bluing solution prepared in step (1). After bluing for 4 to 10 minutes, it is taken out and washed, and then placed in soapy water for saponification for 5 to 10 minutes. Finally, it is taken out, washed, and dried to obtain a uniform and dense dark blue oxide film. Example 2

[0029] (1) Prepare the following ingredients in the following proportions: 20 g / L sodium nitrite, 35 g / L sodium nitrate, 3 g / L potassium pyrophosphate, 3% hydrogen peroxide, 2 g / L sodium phosphate, 1 g / L chelating agent, 1 ml / L OP-10 emulsifier, and adjust the pH to 11 using 180 g / L sodium hydroxide solution.

[0030] (2) Prepare 200 mL of solution according to step (1) and maintain the solution temperature at 25-30°C.

[0031] (3) After grinding and polishing, alkaline washing and degreasing, pickling and derusting, and heating and pre-oxidation, the 13 mm × 13 mm test alloy steel is taken out and immersed in the room temperature bluing solution prepared in step (1). After blackening for 4 to 10 minutes, it is taken out and washed, and then placed in soapy water for saponification for 5 to 10 minutes. Finally, it is taken out, washed, and dried to obtain a uniform and dense dark blue oxide film. Example 3

[0032] (1) Prepare the following ingredients in the following proportions: 20 g / L sodium nitrite, 40 g / L sodium nitrate, 3 g / L potassium pyrophosphate, 6% hydrogen peroxide, 2 g / L sodium phosphate, 1 g / L chelating agent, 1 ml / L OP-10 emulsifier, and adjust the pH to 12 using 210 g / L sodium hydroxide solution.

[0033] (2) Prepare 200 mL of solution according to step (1) and maintain the solution temperature at 25-30°C.

[0034] (3) After grinding and polishing, alkaline washing for oil removal, pickling for rust removal, and heating for pre-oxidation, the 13 mm × 13 mm test alloy steel is taken out and immersed in the room temperature bluing solution prepared in step (1). After bluing for 4 to 10 minutes, it is taken out and washed, and then placed in soapy water for saponification for 5 to 10 minutes. Finally, it is taken out, washed, and dried to obtain a uniform and dense dark blue oxide film. Example 4

[0035] (1) Prepare the following ingredients in the following proportions: 25g / L sodium nitrite, 45g / L sodium nitrate, 3g / L potassium pyrophosphate, 6% hydrogen peroxide, 3g / L sodium phosphate, 1g / L chelating agent, 2ml / L OP-10 emulsifier, and adjust the pH to 12 using 210g / L sodium hydroxide solution.

[0036] (2) Prepare 200 mL of solution according to step (1) and maintain the solution temperature at 25-30°C.

[0037] (3) After grinding and polishing, alkaline washing for oil removal, pickling for rust removal, and heating for pre-oxidation, the 13 mm × 13 mm test alloy steel is taken out and immersed in the room temperature bluing solution prepared in step (1). After bluing for 4 to 10 minutes, it is taken out and washed, and then placed in soapy water for saponification for 5 to 10 minutes. Finally, it is taken out, washed, and dried to obtain a uniform and dense dark blue oxide film.

[0038] In the above embodiment, the Nyquist plots of the sample and bare steel are shown in the attached figure. Figure 1 shown.

[0039] In the above embodiment, the Tafel curves of the sample and bare steel are shown in the attached figure. Figure 2 shown.

[0040] In the above embodiment, the polarization curve fitting results of the sample and bare steel are shown in the following table:

[0041] Polarization curve fitting results of the sample and bare steel in the example

[0042]

[0043] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A room temperature bluing solution suitable for alloy steel, characterized in that: The bluing solution is composed of the following components: 180-240 g / L sodium hydroxide, 15-30 g / L sodium nitrite, 35-50 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L complexing agent and 1-3 ml / L OP-10 emulsifier. The pH of the bluing solution is 10-14.

2. The room temperature bluing solution for alloy steel according to claim 1, characterized in that: The complexing agent is one or more of sodium citrate, tartaric acid, gluconic acid and thiourea.

3. The room temperature bluing solution suitable for alloy steel according to claim 2, characterized in that: The bluing solution is composed of the following components: 200-240 g / L sodium hydroxide, 20-28 g / L sodium nitrite, 35-45 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L complexing agent and 2 ml / L OP-10 emulsifier. The pH of the bluing solution is 11-14.

4. The room temperature bluing solution for alloy steel according to claim 3, characterized in that: The bluing solution is composed of the following components: 200-240g / L sodium hydroxide, 20-28g / L sodium nitrite, 35-45g / L sodium nitrate, 1-4g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8g / L sodium phosphate, 1-4g / L complexing agent and 2ml / L OP-10 emulsifier. The pH of the bluing solution is 12-13.

5. A method for using a room temperature bluing solution suitable for alloy steel, characterized in that: The method is implemented based on the room-temperature bluing solution suitable for alloy steel as described in claim 4, and comprises the following steps: S1. Preparation of bluing solution: Weigh the following components according to the following ratio: 20-28 g / L sodium nitrite, 35-45 g / L sodium nitrate, 1-4 g / L potassium pyrophosphate, 3-12% hydrogen peroxide, 2-8 g / L sodium phosphate, 1-4 g / L chelating agent, and 2 ml / L OP-10 emulsifier. Add these components to a beaker in sequence and mix until all components are fully dissolved. Adjust the pH to 12-13 with 200-240 g / L sodium hydroxide to obtain a bluing solution. S2: The alloy steel used in the experiment is sequentially ground and polished, alkaline-washed for oil removal, pickled for rust removal, and high-temperature pre-oxidized. The alloy steel after high-temperature pre-oxidation is then directly placed in the bluing solution prepared in step S1 for quenching. After oxidation and bluing, the alloy steel is taken out and placed in soapy water at a temperature of 70-100°C for saponification for 5-10 minutes. The alloy steel is then taken out, washed, and dried.

6. The method for using a room temperature bluing solution suitable for alloy steel according to claim 5, characterized in that: The blueing time of alloy steel after high-temperature pre-oxidation is 4-10 minutes.

7. The method for using a room temperature bluing solution for alloy steel according to claim 6, characterized in that: The blueing time of alloy steel after high-temperature pre-oxidation is 5 minutes.

8. The method for using a room temperature bluing solution suitable for alloy steel according to claim 5, characterized in that: The high temperature pre-oxidation temperature of alloy steel is 350-500℃.

9. The method for using a room temperature bluing solution suitable for alloy steel according to claim 5, characterized in that: The high-temperature pre-oxidation time of alloy steel is 10-15 minutes.

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