Electrochemical surface inclusion removing based super corrosion resistance treatment method of stainless steel

Abstract

The invention belongs to the field of material surface treatment, and provides an electrochemical surface inclusion removing based super corrosion resistance treatment method of a stainless steel. Themethod specifically comprises the following steps: (1) washing and removing oil; pickling; and passivating to obtain a pre-treated surface; (2) feeding the pre-treated surface in a 4-10mol / L by concentration of NaNo3 solution under the temperature of 40-60 DEG C; and performing a multicycle potential step control method to remove a surface inclusion and thicken the passivating film so as to improve the protection performance of the passivating film; and (3) washing with water; drying; and storing. According to the method, a method combining chemical passivation of nitric acid and multicycle potential step control of sodium nitrate is carried out; means of electrochemically removing the inclusions and thickening the passivating film are combined to realize ultrahigh corrosion resistance ofthe stainless steel under high temperature and high salinity. According to the method, the passivating solution and the electrochemical passivating method are simple and convenient, and the operationis easy; the strict requirement of the stainless steel on the corrosion resistance under the high temperature and high salinity conditions.

Description

technical field

[0001] The invention belongs to the field of material surface treatment and relates to an electrochemical treatment method for removing inclusions on the surface of stainless steel and improving the corrosion resistance of a passivation film. Background technique

[0002] 430, 443, 304 and other stainless steels have become widely used materials in marine engineering, nuclear engineering, aerospace, medicine, high-speed rail and other industries due to their low price, good corrosion resistance and machining performance. The quality of surface passivation film and the physical and chemical properties of inclusions are the key to the corrosion resistance of stainless steel. In engineering, passivation methods are often used to enhance the quality of surface passivation film to improve the corrosion resistance of stainless steel.

[0003] Traditional passivation methods include nitric acid-based chemical passivation methods and other electrochemical passivatio...

Examples

Embodiment 1

[0021] Example 1 Multi-period potential step control method to remove inclusions

[0022] The solution used in the inventive method is: the mass percentage is the NaNO of 20% nitric acid, 5mol / L 3 Solution, the water used to configure the solution is deionized water, the mass percentage concentration of the chemical reagent nitric acid used is 68%, NaNO 3 For analytically pure reagents.

[0023] Use the different passivation treatment steps in the above-mentioned embodiment 1 as follows:

[0024] (1) Put the sample into 20% nitric acid solution at 50°C for passivation for 0.5h and then clean it;

[0025] (2) Put the cleaned sample in 5mol / L NaNO at 50°C 3 Multi-cycle potential step treatment is carried out in the solution, and the counter electrode is made of duplex stainless steel. The single-cycle electrochemical treatment includes the following three stages: first, the anode step potential is changed from 0.5V to SSE Linearly polarized to 0.8V SSE , the processing time...

Embodiment 2

[0028] Example 2 Multi-period potential step control method to remove inclusions

[0029] The solution used in the inventive method is: the nitric acid solution that the mass percent is 20%, the NaNO that concentration is 5mol / L 3 Solution, the water used to configure the solution is deionized water, the mass percentage concentration of the chemical reagent nitric acid used is 68%, NaNO 3 For analytically pure reagents.

[0030] Use different passivation treatment steps in the above-mentioned embodiment 2 as follows:

[0031] (1) Passivate a part of the sample in 50°C, 20% nitric acid solution for 0.5h, and ultrasonically clean it with deionized water;

[0032] (2) Put the sample in 5mol / L NaNO at 40°C 3 After 300 cycles of potential step treatment in the solution: a titanium plate is used for the counter electrode, and the anode step potential is from 0.5V SSE to 0.8V SSE , the processing time is 17s, the cathode potential is -0.5V SSE , the processing time is 5s, and f...

Embodiment 3

[0034] Example 3 Multi-period potential step control method to remove inclusions

[0035] A stainless steel super corrosion-resistant treatment method based on electrochemical removal of surface inclusions, comprising the following steps:

[0036](1) After degreasing and cleaning the surface of the stainless steel object to be treated, it is placed in a 50°C, 5wt.% sulfuric acid solution for passivation treatment to obtain a pretreated surface.

[0037] (2) Remove the inclusions on the pretreatment surface to thicken the passivation film and improve the protection of the passivation film

[0038] Put the sample in 10mol / L NaNO at 60℃ 3 After 20 cycles of potential step treatment in the solution: graphite is used as the counter electrode, and the anode step potential is from 0.5V SSE to 0.8V SSE , the processing time is 20.5s, the cathode potential is -0.1V SSE , the processing time is 7.5s, and finally step to the initial potential of 0.5V SSE , keep 2s, single cycle time...

technical field

[0001] The invention belongs to the field of material surface treatment and relates to an electrochemical treatment method for removing inclusions on the surface of stainless steel and improving the corrosion resistance of a passivation film. Background technique

[0002] 430, 443, 304 and other stainless steels have become widely used materials in marine engineering, nuclear engineering, aerospace, medicine, high-speed rail and other industries due to their low price, good corrosion resistance and machining performance. The quality of surface passivation film and the physical and chemical properties of inclusions are the key to the corrosion resistance of stainless steel. In engineering, passivation methods are often used to enhance the quality of surface passivation film to improve the corrosion resistance of stainless steel.

[0003] Traditional passivation methods include nitric acid-based chemical passivation methods and other electrochemical passivatio...

Examples

Embodiment 1

[0021] Example 1 Multi-period potential step control method to remove inclusions

[0022] The solution used in the inventive method is: the mass percentage is the NaNO of 20% nitric acid, 5mol / L 3 Solution, the water used to configure the solution is deionized water, the mass percentage concentration of the chemical reagent nitric acid used is 68%, NaNO 3 For analytically pure reagents.

[0023] Use the different passivation treatment steps in the above-mentioned embodiment 1 as follows:

[0024] (1) Put the sample into 20% nitric acid solution at 50°C for passivation for 0.5h and then clean it;

[0025] (2) Put the cleaned sample in 5mol / L NaNO at 50°C 3 Multi-cycle potential step treatment is carried out in the solution, and the counter electrode is made of duplex stainless steel. The single-cycle electrochemical treatment includes the following three stages: first, the anode step potential is changed from 0.5V to SSE Linearly polarized to 0.8V SSE , the processing time...

Embodiment 2

[0028] Example 2 Multi-period potential step control method to remove inclusions

[0029] The solution used in the inventive method is: the nitric acid solution that the mass percent is 20%, the NaNO that concentration is 5mol / L 3 Solution, the water used to configure the solution is deionized water, the mass percentage concentration of the chemical reagent nitric acid used is 68%, NaNO 3 For analytically pure reagents.

[0030] Use different passivation treatment steps in the above-mentioned embodiment 2 as follows:

[0031] (1) Passivate a part of the sample in 50°C, 20% nitric acid solution for 0.5h, and ultrasonically clean it with deionized water;

[0032] (2) Put the sample in 5mol / L NaNO at 40°C 3 After 300 cycles of potential step treatment in the solution: a titanium plate is used for the counter electrode, and the anode step potential is from 0.5V SSE to 0.8V SSE , the processing time is 17s, the cathode potential is -0.5V SSE , the processing time is 5s, and f...

Embodiment 3

[0034] Example 3 Multi-period potential step control method to remove inclusions

[0035] A stainless steel super corrosion-resistant treatment method based on electrochemical removal of surface inclusions, comprising the following steps:

[0036](1) After degreasing and cleaning the surface of the stainless steel object to be treated, it is placed in a 50°C, 5wt.% sulfuric acid solution for passivation treatment to obtain a pretreated surface.

[0037] (2) Remove the inclusions on the pretreatment surface to thicken the passivation film and improve the protection of the passivation film

[0038] Put the sample in 10mol / L NaNO at 60℃ 3 After 20 cycles of potential step treatment in the solution: graphite is used as the counter electrode, and the anode step potential is from 0.5V SSE to 0.8V SSE , the processing time is 20.5s, the cathode potential is -0.1V SSE , the processing time is 7.5s, and finally step to the initial potential of 0.5V SSE , keep 2s, single cycle time...

Images