Passivation solution and passivation method for high-carbon-chromium stainless steel passivation film

Abstract

The invention discloses a passivation solution and passivation method for a high-carbon-chromium stainless steel passivation film, the passivation solution comprises a first passivation solution and a second passivation solution, the first passivation solution is composed of 5-30% of citric acid, 11-32% of 1-hydroxyethylidene-1, 1-diphosphonic acid, 5-9% of hydrolytic polymaleic anhydride and deionized water; and the second passivation solution contains 0.5-2.5% of imidazoline, 2-4% of polyethylene glycol, deionized water and the like. According to the passivation method, a sample is demagnetized after being machined, so that the residual magnetism is smaller than or equal to 0.2 mt; performing ultrasonic cleaning and oil stain removal in oil removal liquid at 75-95 DEG C; after cleaning, passivating twice at 55-65 DEG C by using a first passivating solution and a second passivating solution respectively; and after neutralization, drying at 70-80 DEG C for 10-15 minutes, and coating oil to prevent rust. The method has a good passivation effect, and the corrosion-resistant effect of the high-carbon-chromium stainless steel is guaranteed.

Description

Technical Field

[0001] The invention relates to a passivation solution and a passivation method for a high-carbon chromium stainless steel passivation film. Background Art

[0002] High-carbon chromium stainless steel is one of the commonly used materials for manufacturing bearing parts, but it has significant defects. The primary carbides in this material are relatively coarse, and there are a large number of crystal defects such as dislocations. The presence of these defects will form many microscopic stress concentration areas and corrosion-sensitive sites inside the material. When high-carbon chromium stainless steel is used to make bearing parts and undergo corrosion resistance tests, the above defects will make the parts more susceptible to electrochemical corrosion in a neutral salt spray environment. According to the GJB150.11A standard, bearing parts must pass a 96-hour neutral salt spray test, but due to the defects of the high-carbon chromium stainless steel material itself, these bearing parts often find it difficult to meet this corrosion resistance time requirement in actual tests, which in turn affects their application reliability in highly corrosive environments. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the present invention provides a passivation solution and a passivation method for a high-carbon chromium stainless steel passivation film, which has a good passivation effect and ensures the corrosion resistance of the high-carbon chromium stainless steel.

[0004] To achieve the above object, the present invention provides a passivation solution for a high-carbon chromium stainless steel passivation film, comprising a first passivation solution and a second passivation solution, wherein the first passivation solution comprises 5-30% citric acid, 11-32% hydroxyethylidene diphosphoric acid, 5-9% hydrolyzed polymaleic anhydride and deionized water; and the second passivation solution comprises 0.5-2.5% imidazoline, 2-4% polyethylene glycol, 1-8% triethanolamine, 0.5-1% sodium metasilicate and deionized water.

[0005] The present invention also provides a passivation method for a passivation solution for a high-carbon chromium stainless steel passivation film, comprising the following steps:

[0006] Step 1: Demagnetization: After the sample is processed, use a demagnetization machine to demagnetize it, and the residual magnetism detector detects that the residual magnetism is ≤0.2mt;

[0007] Step 2: Degreasing: Immerse the sample completely in a degreasing solution at a temperature of 75°C to 95°C and clean it ultrasonically for 5 to 10 minutes. The degreasing solution is a mixture of 25 to 35 g / L anhydrous sodium carbonate, 25 to 35 g / L trisodium phosphate, 10 to 20 g / L sodium hydroxide, and the remainder deionized water.

[0008] Step 3: Cleaning: First, clean with hot water at 75-85°C for 1-2 minutes, then clean with distilled water for 1-2 minutes;

[0009] Step 4: First passivation: Place the sample in the passivation tank, add the first passivation solution, maintain the temperature at 55-65°C, and keep the temperature constant for 30-35 minutes;

[0010] Step 5: Second passivation: Place the bearing parts in the coordination tank, add the second passivation solution, maintain the temperature at 55℃~65℃, and perform constant temperature coordination treatment for 30 minutes;

[0011] Step 6: Neutralization: Immerse the cleaned bearing parts completely in the neutralization solution and shake them for 1 to 2 minutes.

[0012] Step 7, drying and rust prevention: Dry the bearing parts. The drying temperature should be maintained at 70-80℃ and the drying time should be 10-15 minutes. After drying, apply oil for protection.

[0013] As a further configuration of the present invention, the steps 4, 5 and 6 need to be washed with clean water respectively, and the washing time is 1 to 2 minutes.

[0014] As a further configuration of the present invention, the neutralization solution in step six comprises 30-50 g / L sodium carbonate and the remainder deionized water.

[0015] This configuration offers the following benefits: citric acid, a mild and highly effective oxidant, complexes with metal ions on the stainless steel surface, promoting uniform oxidation and forming the foundational structure of the passivation film. The addition of hydroxyethylidene diphosphonic acid (HEDP) provides a key synergistic effect, forming a stable chemically adsorbed layer on the metal surface, effectively inhibiting metal dissolution and enhancing the stability of the passivation film. The corrosion inhibitor hydrolyzes polymaleic anhydride, forming a dense protective film on the metal surface, slowing contact between the corrosive medium and the metal, further enhancing the protective capabilities of the passivation film. A double passivation process is employed. The first passivation treatment is conducted at a constant temperature of 55-65°C for 30-35 minutes, allowing the passivation solution to fully react with the stainless steel surface and initially form a passivation film. The second passivation treatment involves placing the part in the coordination bath again and conducting a constant temperature coordination treatment at the same temperature for 30 minutes. This step allows the components in the passivation solution to further penetrate and react, filling the tiny pores and defects in the passivation film formed during the first passivation, significantly increasing the thickness and density of the passivation film. The high-carbon chromium stainless steel treated with this method performed excellently in the neutral salt spray test. The corrosion resistance time was increased from 96 hours, which was difficult to meet the GJB150.11A standard, to at least 240 hours without rust, greatly enhancing the reliability and service life of bearing parts in harsh corrosive environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a state diagram of a high carbon chromium stainless steel bearing passivated by the existing method and subjected to an acid mist test for 0 hours;

[0017] Figure 2 This is a state diagram of a high-carbon chromium stainless steel bearing passivated using the existing method and subjected to an acid mist test for 96 hours;

[0018] Figure 3 This is a state diagram of a high-carbon chromium stainless steel bearing passivated using the existing method and subjected to an acid mist test for 192 hours;

[0019] Figure 4 This is a state diagram of a high carbon chromium stainless steel bearing passivated using the existing method and subjected to an acid mist test for 244 hours;

[0020] Figure 5 This is the state diagram of the high carbon chromium stainless steel bearing after the acid mist test lasting 0h after the passivation liquid and passivation method are used;

[0021] Figure 6 This is a state diagram of a high carbon chromium stainless steel bearing after using passivation liquid and passivation method under acid mist test for 96 hours;

[0022] Figure 7 This is a state diagram of a high carbon chromium stainless steel bearing after using passivation liquid and passivation method under acid mist test for 192 hours;

[0023] Figure 8 This is a state diagram of a high carbon chromium stainless steel bearing under an acid mist test for 244 hours after using passivation liquid and passivation method. DETAILED DESCRIPTION

[0024] The present invention discloses a passivation solution for high carbon chromium stainless steel passivation film and a passivation method using the passivation solution, such as Figures 5 to 8 As shown: a passivation solution for a high-carbon chromium stainless steel passivation film, comprising a first passivation solution and a second passivation solution, wherein the first passivation solution comprises 27% citric acid, 19% hydroxyethylidene diphosphoric acid, 7% hydrolyzed polymaleic anhydride and deionized water; the second passivation solution comprises 2.2% imidazoline, 3.6% polyethylene glycol, 5.7% triethanolamine, 0.65% sodium metasilicate and deionized water.

[0025] The passivation method of the passivation solution for high carbon chromium stainless steel passivation film comprises the following steps:

[0026] Step 1: Demagnetization: After the sample is processed, use a demagnetization machine to demagnetize it, and the residual magnetism detector detects that the residual magnetism is ≤0.2mt;

[0027] Step 2: Degreasing: The specimen was completely immersed in a degreasing solution at 77°C and ultrasonically cleaned for 8 minutes. The degreasing solution was a mixture of 29 g / L anhydrous sodium carbonate, 26.7 g / L trisodium phosphate, 12 g / L sodium hydroxide, and the remainder deionized water.

[0028] Step 3: Cleaning: First, clean with 77°C hot water for 2 minutes, then with distilled water for 1-2 minutes. After cleaning, inspect the sample for a continuous water film. Wet the surface of the part and visually observe for at least 20 seconds without any water film breakage. The sample is considered acceptable before proceeding to the next step. After cleaning, passivate the sample within 10 minutes. Avoid direct sunlight to prevent rusting.

[0029] Step 4, first passivation: Place the sample in the passivation tank, add the first passivation solution, maintain the temperature at 58°C, and treat at this constant temperature for 31 minutes; after passivation, rinse with clean water for 2 minutes;

[0030] Step 5: Second passivation: Place the bearing parts in the coordination tank, add the second passivation solution, maintain the temperature at 58°C, and perform constant temperature coordination treatment for 30 minutes; after passivation, rinse with clean water for 2 minutes;

[0031] Step 6: Neutralization: Immerse the cleaned bearing parts completely in a neutralizing solution containing 35g / L sodium carbonate and the remainder deionized water, and shake for 2 minutes. Rinse with clean water for 2 minutes after neutralization.

[0032] Step 7, drying and rust prevention: Dry the bearing parts. The drying temperature should be maintained at 77°C and the drying time should be 15 minutes. After drying, apply oil for protection.

[0033] The above example is only one preferred specific example of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A passivation solution for high carbon chromium stainless steel passivation film, characterized by: The invention comprises a first passivation solution and a second passivation solution, wherein the first passivation solution comprises 5-30% citric acid, 11-32% hydroxyethylidene diphosphoric acid, 5-9% hydrolyzed polymaleic anhydride and deionized water; and the second passivation solution comprises 0.5-2.5% imidazoline, 2-4% polyethylene glycol, 1-8% triethanolamine, 0.5-1% sodium metasilicate and deionized water.

2. A passivation method based on the passivation solution for high carbon chromium stainless steel passivation film according to claim 1, characterized in that: The following steps are involved: Step 1: Demagnetization: After the sample is processed, use a demagnetization machine to demagnetize it, and the residual magnetism detector detects that the residual magnetism is ≤0.2mt; Step 2: Degreasing: Immerse the sample completely in a degreasing solution at a temperature of 75°C to 95°C and clean it ultrasonically for 5 to 10 minutes. The degreasing solution is a mixture of 25 to 35 g / L anhydrous sodium carbonate, 25 to 35 g / L trisodium phosphate, 10 to 20 g / L sodium hydroxide, and the remainder deionized water. Step 3: Cleaning: First, clean with hot water at 75-85°C for 1-2 minutes, then clean with distilled water for 1-2 minutes; Step 4: First passivation: Place the sample in the passivation tank, add the first passivation solution, maintain the temperature at 55-65°C, and keep the temperature constant for 30-35 minutes; Step 5: Second passivation: Place the bearing parts in the coordination tank, add the second passivation solution, maintain the temperature at 55℃~65℃, and perform constant temperature coordination treatment for 30 minutes; Step 6: Neutralization: Immerse the cleaned bearing parts completely in the neutralization solution and shake them for 1 to 2 minutes. Step 7, drying and rust prevention: Dry the bearing parts. The drying temperature should be maintained at 70-80℃ and the drying time should be 10-15 minutes. After drying, apply oil for protection.

3. The passivation method of the passivation solution for high carbon chromium stainless steel passivation film according to claim 2, characterized in that: After step 4, step 5 and step 6, the mixture needs to be washed with clean water for 1 to 2 minutes.

4. The passivation method of the passivation solution for high carbon chromium stainless steel passivation film according to claim 3, characterized in that: The neutralization solution in step six comprises 30-50 g / L sodium carbonate and the balance deionized water.

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