Chemical polishing solution and application thereof
By optimizing the component ratio and mixing process of the chemical polishing liquid, the scratches and wear problems of stainless steel surfaces are solved, and efficient surface polishing effect and stable production capacity are achieved.
Patent Information
- Application Number
- CN202510246777.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-07-25
AI Technical Summary
When using stainless steel surfaces, existing chemical polishing liquids are difficult to effectively remove appearance defects such as scratches and wear, resulting in poor surface quality.
By optimizing the ratio of solvents, oxidants, brighteners, complexing agents, dispersants, defoaming agents and corrosion inhibitors and ultrasonic dispersion time, a chemical polishing liquid is prepared to ensure that the components are evenly mixed and effectively remove defects on the surface of stainless steel.
It significantly improves the smoothness and flatness of the stainless steel surface, improves the stability and production efficiency of the polishing liquid, and meets the needs of industrial production.
Smart Images
Figure CN120366788A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of metal surface treatment, and specifically relates to a chemical polishing solution and its use. Background Art
[0002] Implantable metal medical devices play a crucial role in the medical field. The surface quality of medical devices not only affects their use effect but also directly relates to the treatment effect and the incidence of complications. Therefore, it is particularly important to control the surface quality of metal medical devices. As an important surface treatment technology, chemical polishing has a significant effect on improving the surface quality of metal medical devices. Through chemical polishing, minute defects, scratches, and oxide layers on the metal surface can be removed, making the surface smoother and flatter.
[0003] Chemical polishing demonstrates various advantages in the field of metal surface treatment, especially in the surface treatment of medical devices. Chemical polishing can effectively remove minute defects and scratches on the metal surface, making the surface of medical devices smoother and more uniform. This treatment method can not only significantly improve the surface finish of the device but also reduce the friction between the device and human tissues, endowing the device with better biocompatibility, thereby reducing the risk of infection and further enhancing the safety and performance of medical devices. Compared with traditional polishing methods, chemical polishing shows unique advantages in processing medical device parts with complex shapes. It is applicable to a variety of metal materials, including stainless steel and other materials commonly used in medical devices, and can efficiently process small lumens, curved surfaces, and workpieces with complex mesh structures such as cardiac stents. In addition, chemical polishing does not require complex equipment, can process multiple workpieces simultaneously, and has a short processing time, significantly improving production efficiency and being able to meet production requirements faster. These characteristics make chemical polishing an indispensable technical means in the surface treatment of medical devices. Summary of the Invention
[0004] Aiming at the above problems existing in the prior art, the purpose of the present invention is to design and provide a technical solution for a chemical polishing solution and its use. By using this polishing solution, surface defects of stainless steel can be eliminated, appearance problems such as scratches and wear can be solved, and the surface quality of the material can be improved.
[0005] The described chemical polishing solution is characterized by being prepared by the following method: 1) Add to a beaker according to the mass ratio of solvent A: oxidant: brightener: complexing agent of 100: 0.1 - 2: 0.1 - 2: 0.1 - 2, and ultrasonically disperse for 10 - 60 min at room temperature to obtain solution A; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100: 0.1 - 2: 0.1 - 2: 0.1 - 2, and obtain solution B after ultrasonic dispersion at room temperature for 10 - 60 min; 3) Add them to a beaker according to the mass ratio of hydrochloric acid: nitric acid of 2 - 4: 1, and obtain a pH regulator after ultrasonic treatment for 15 - 25 min; 4) Add solution A, solution B, and the pH regulator to a beaker according to the mass ratio of 90 - 110: 90 - 110: 0.1 - 1, and obtain a chemical polishing solution after ultrasonic dispersion at room temperature for 10 - 60 min.
[0006] For the described chemical polishing solution, it is characterized in that in step 1): the mass ratio of solvent A: oxidant: brightener: complexing agent is 100: 0.5 - 1.5: 0.5 - 1.5: 0.5 - 1.5, preferably 100: 0.8 - 1: 0.8 - 1: 0.8 - 1; the ultrasonic dispersion time is 20 - 50 min, preferably 30 - 40 min of ultrasonic dispersion.
[0007] For the described chemical polishing solution, it is characterized in that in step 1): the solvent A is ethanol and the solvent purity is chromatographic pure; the oxidant is at least one of hydrogen peroxide and sodium bisulfate, and the drug purity is chromatographic pure; the brightener is at least one of thiourea, salicylic acid, and sodium dodecylbenzenesulfonate, and the drug purity is chromatographic pure; the complexing agent is at least one of glycine and chitosan oligosaccharide, and the drug purity is chromatographic pure.
[0008] For the described chemical polishing solution, it is characterized in that in step 2): the mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor is 100: 0.5 - 1.5: 0.5 - 1.5: 0.5 - 1.5; preferably 100: 1 - 1.2: 1 - 1.2: 1 - 1.2; the ultrasonic dispersion time is 20 - 50 min, preferably 30 - 40 min of ultrasonic dispersion.
[0009] For the described chemical polishing solution, it is characterized in that in step 2): the solvent B is DMF and the drug purity is chromatographic pure; the dispersant is polyethylene glycol and the drug purity is chromatographic pure; the defoamer is glycerol and the drug purity is chromatographic pure; the corrosion inhibitor is sodium benzoate and the drug purity is chromatographic pure.
[0010] For the described chemical polishing solution, it is characterized in that in step 3): add hydrochloric acid and nitric acid to the beaker according to the mass ratio of 3: 1, and perform ultrasonic treatment for 20 min.
[0011] For the described chemical polishing solution, it is characterized in that in step 3): both the hydrochloric acid and nitric acid are of analytical purity.
[0012] The described chemical polishing solution is characterized in step 4) that: Solution A, Solution B, and the pH regulator are in a mass ratio of 100:100:0.2 - 0.8; preferably 100:100:0.4 - 0.6; the ultrasonic dispersion time is 20 - 50 min, preferably 30 - 40 min of ultrasonic dispersion.
[0013] Application of the described chemical polishing solution in metal surface treatment.
[0014] Application of the described chemical polishing solution in stainless steel surface treatment, especially in the surface treatment of 316L stainless steel.
[0015] The present invention has the following positive effects compared with the prior art: In the present invention, an oxidizing agent, a brightening agent, and a complexing agent are added to an ethanol solvent and ultrasonically mixed to obtain Solution A. Then, a dispersant, an antifoaming agent, and an inhibitor are added to DMF and ultrasonically mixed to obtain Solution B. Then, hydrochloric acid and nitric acid are prepared into a pH regulator. Finally, Solution A, Solution B, and the pH regulator are uniformly mixed to obtain a stainless steel chemical polishing solution. The additives in this specific embodiment mainly include an oxidizing agent, a brightening agent, a complexing agent, a dispersant, an antifoaming agent, and an inhibitor, etc., which play a key role in enhancing the polishing effect and protecting the surface. However, the dosage of the additives needs to be precisely controlled: excessive use will cause uneven surfaces or spots; while insufficient dosage will result in rough surfaces and decreased gloss. The main function of the pH regulator is to maintain the acid-base balance of the polishing solution, thereby regulating the chemical reaction rate and surface treatment effect. It should be noted that excessive use of the pH regulator may cause over-corrosion, damage the stainless steel surface, and increase the difficulty of waste liquid treatment; on the contrary, insufficient dosage will lead to unstable performance of the polishing solution and significantly reduce the polishing effect. The solvent, as the basic component of the polishing solution, mainly functions to dissolve other components and maintain the uniformity and stability of the system. Excessive solvent will dilute the effective components in the polishing solution, resulting in weakened polishing effect; while insufficient solvent will affect the full dissolution of the effective components and also reduce the polishing effect.
[0016] Therefore, by optimizing the ratios of the additives, the pH regulator, and the solvent, the present invention achieves full contact and uniform reaction between the polishing solution and the stainless steel surface, thereby significantly improving the product stability and polishing performance; specifically, the polishing solution prepared by the present invention not only exhibits excellent metal removal rate but also has high production capacity, meeting the requirements of industrial production. Brief Description of the Drawings
[0017] Figure 1 It is the SEM image of 316L stainless steel after polishing; Figure 2 It is the SEM image of 316L stainless steel without polishing. Detailed Description of the Invention
[0018] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments and the accompanying drawings. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention. In the specific embodiments of the present invention: The solvent A is ethanol, and the solvent B is DMF, and the purity of both solvents is above chromatographic purity.
[0019] The dispersant is polyethylene glycol, the defoaming agent is glycerol, and the corrosion inhibitor is sodium benzoate.
[0020] The purity of the additive is above chromatographic purity.
[0021] The comparative examples and the examples will not be elaborated further.
[0022] Comparative Example 1 1) Add to a beaker in a mass ratio of solvent A: oxidant: brightener: complexing agent of 100:0.01:0.01:0.01, and ultrasonically disperse for 10 min at room temperature to obtain solution A; 2) Add to a beaker in a mass ratio of solvent B: dispersant: defoaming agent: corrosion inhibitor of 100:0.01:0.01:0.01, and ultrasonically disperse for 10 min at room temperature to obtain solution B; 3) Add to a beaker in a mass ratio of hydrochloric acid: nitric acid of 3:1, and ultrasonically disperse for 20 min to obtain a pH regulator; 4) Add solution A, solution B and the pH regulator to a beaker in a mass ratio of 100:100:0.1, and ultrasonically disperse for 10 min at room temperature to obtain a chemical polishing solution.
[0023] In this example: the oxidant is hydrogen peroxide; the brightener is thiourea; the complexing agent is glycine.
[0024] Comparative Example 2 1) Add to a beaker in a mass ratio of solvent A: oxidant: brightener: complexing agent of 100:20:20:20, and ultrasonically disperse for 60 min at room temperature to obtain solution A; 2) Add to a beaker in a mass ratio of solvent B: dispersant: defoaming agent: corrosion inhibitor of 100:20:20:20, and ultrasonically disperse for 60 min at room temperature to obtain solution B; 3) Add to a beaker in a mass ratio of hydrochloric acid: nitric acid of 3:1, and ultrasonically disperse for 20 min to obtain a pH regulator; 4) Solution A, solution B and the pH regulator were added to a beaker at a mass ratio of 100:100:1, and ultrasonic dispersion was carried out for 60 min at room temperature to obtain a chemical polishing solution.
[0025] In this example: the oxidant is hydrogen peroxide; the brightener is thiourea and salicylic acid, and the mass ratio of thiourea to salicylic acid is 5:5; the complexing agent is chitosan oligosaccharide.
[0026] Example 1 1) They were added to a beaker at a mass ratio of solvent A: oxidant: brightener: complexing agent of 100:0.1:0.1:0.1, and ultrasonic dispersion was carried out for 10 min at room temperature to obtain solution A; 2) They were added to a beaker at a mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100:0.1:0.1:0.1, and ultrasonic dispersion was carried out for 10 min at room temperature to obtain solution B; 3) Hydrochloric acid and nitric acid were added to a beaker at a mass ratio of 3:1, and ultrasonic treatment was carried out for 20 min to obtain the pH regulator; 4) Solution A, solution B and the pH regulator were added to a beaker at a mass ratio of 100:100:0.1, and ultrasonic dispersion was carried out for 10 min at room temperature to obtain a chemical polishing solution; In this example: the oxidant is hydrogen peroxide; the brightener is thiourea; the complexing agent is glycine.
[0027] Example 2 1) They were added to a beaker at a mass ratio of solvent A: oxidant: brightener: complexing agent of 100:1.4:1.2:0.9, and ultrasonic dispersion was carried out for 15 min at room temperature to obtain solution A; 2) They were added to a beaker at a mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100:1.1:0.8:1.3, and ultrasonic dispersion was carried out for 15 min at room temperature to obtain solution B; 3) Hydrochloric acid and nitric acid were added to a beaker at a mass ratio of 3:1, and ultrasonic treatment was carried out for 20 min to obtain the pH regulator; 4) Solution A, solution B and the pH regulator were added to a beaker at a mass ratio of 100:100:0.2, and ultrasonic dispersion was carried out for 20 min at room temperature to obtain a chemical polishing solution; In this example: the oxidant is sodium bisulfate; the brightener is thiourea; the complexing agent is glycine.
[0028] Example 3 1) Add them to a beaker according to the mass ratio of solvent A: oxidant: brightener: complexing agent of 100:2.2:2.5:1.9, and obtain solution A after ultrasonic dispersion for 20 min at room temperature; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100:2.3:2.8:1.7, and obtain solution B after ultrasonic dispersion for 20 min at room temperature; 3) Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 3:1, and obtain a pH regulator after ultrasonic treatment for 20 min; 4) Add solution A, solution B and the pH regulator to a beaker according to the mass ratio of 100:100:0.3, and obtain a chemical polishing solution after ultrasonic dispersion for 20 min at room temperature; In this example: the oxidant is hydrogen peroxide; the brightener is salicylic acid; the complexing agent is chitosan oligosaccharide.
[0029] Example 4 1) Add them to a beaker according to the mass ratio of solvent A: oxidant: brightener: complexing agent of 100:3.8:3.6:3.5, and obtain solution A after ultrasonic dispersion for 25 min at room temperature; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100:3.3:3.7:3.4, and obtain solution B after ultrasonic dispersion for 25 min at room temperature; 3) Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 3:1, and obtain a pH regulator after ultrasonic treatment for 20 min; 4) Add solution A, solution B and the pH regulator to a beaker according to the mass ratio of 100:100:0.4, and obtain a chemical polishing solution after ultrasonic dispersion for 20 min at room temperature; In this example: the oxidant is hydrogen peroxide and sodium bisulfate, and the mass ratio of hydrogen peroxide to sodium bisulfate is 6:4; the brightener is salicylic acid; the complexing agent is chitosan oligosaccharide.
[0030] Example 5 1) Add them to a beaker according to the mass ratio of solvent A: oxidant: brightener: complexing agent of 100:4.7:4.9:4.6, and obtain solution A after ultrasonic dispersion for 30 min at room temperature; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100:4.4:4.3:4.7, and obtain solution B after ultrasonic dispersion for 30 min at room temperature; 3) Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 3:1, and obtain a pH regulator after ultrasonic treatment for 20 min; 4) Add solution A, solution B, and the pH regulator into a beaker at a mass ratio of 100:100:0.5, and ultrasonically disperse for 20 min at room temperature to obtain a chemical polishing solution; In this example: the oxidizing agent is sodium bisulfate; the brightening agent is sodium dodecylbenzenesulfonate; the complexing agent is chitosan oligosaccharide.
[0031] Example 6 1) Add into a beaker at a mass ratio of solvent A:oxidizing agent:brightening agent:complexing agent of 100:6.1:5.9:5.7, and ultrasonically disperse for 30 min at room temperature to obtain solution A; 2) Add into a beaker at a mass ratio of solvent B:dispersant:defoamer:corrosion inhibitor of 100:5.5:5.8:6.2, and ultrasonically disperse for 30 min at room temperature to obtain solution B; 3) Add hydrochloric acid and nitric acid into a beaker at a mass ratio of 3:1, and ultrasonically disperse for 20 min to obtain the pH regulator; 4) Add solution A, solution B, and the pH regulator into a beaker at a mass ratio of 100:100:0.6, and ultrasonically disperse for 30 min at room temperature to obtain a chemical polishing solution; In this example: the oxidizing agent is sodium bisulfate; the brightening agent is sodium dodecylbenzenesulfonate; the complexing agent is chitosan oligosaccharide.
[0032] Example 7 1) Add into a beaker at a mass ratio of solvent A:oxidizing agent:brightening agent:complexing agent of 100:7.4:7.2:6.9, and ultrasonically disperse for 40 min at room temperature to obtain solution A; 2) Add into a beaker at a mass ratio of solvent B:dispersant:defoamer:corrosion inhibitor of 100:7.2:7.3:7.1, and ultrasonically disperse for 40 min at room temperature to obtain solution B; 3) Add hydrochloric acid and nitric acid into a beaker at a mass ratio of 3:1, and ultrasonically disperse for 20 min to obtain the pH regulator; 4) Add solution A, solution B, and the pH regulator into a beaker at a mass ratio of 100:100:0.7, and ultrasonically disperse for 40 min at room temperature to obtain a chemical polishing solution; In this example: the oxidizing agent is hydrogen peroxide; the brightening agent is salicylic acid; the complexing agent is glycine and chitosan oligosaccharide, and the mass ratio of glycine to chitosan oligosaccharide is 7:3.
[0033] Example 8 1) Add them to a beaker according to the mass ratio of solvent A: oxidant: brightening agent: complexing agent of 100:8.4:8.6:8.7, and obtain solution A after ultrasonic dispersion at room temperature for 50 min; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoaming agent: corrosion inhibitor of 100:8.1:8.5:8.3, and obtain solution B after ultrasonic dispersion at room temperature for 50 min; 3) Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 3:1, and obtain the pH regulator after ultrasonic treatment for 20 min; 4) Add solution A, solution B and the pH regulator to a beaker according to the mass ratio of 100:100:0.85, and obtain the chemical polishing solution after ultrasonic dispersion at room temperature for 50 min.
[0034] In this example: the oxidant is hydrogen peroxide; the brightening agent is salicylic acid; the complexing agent is chitosan oligosaccharide.
[0035] Example 9 1) Add them to a beaker according to the mass ratio of solvent A: oxidant: brightening agent: complexing agent of 100:10:10:10, and obtain solution A after ultrasonic dispersion at room temperature for 60 min; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoaming agent: corrosion inhibitor of 100:10:10:10, and obtain solution B after ultrasonic dispersion at room temperature for 60 min; 3) Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 3:1, and obtain the pH regulator after ultrasonic treatment for 20 min; 4) Add solution A, solution B and the pH regulator to a beaker according to the mass ratio of 100:100:1, and obtain the chemical polishing solution after ultrasonic dispersion at room temperature for 60 min; In this example: the oxidant is hydrogen peroxide; the brightening agent is thiourea and salicylic acid, and the mass ratio of thiourea to salicylic acid is 5:5; the complexing agent is chitosan oligosaccharide.
[0036] The technical effects of the present invention are further demonstrated by the following corresponding experimental data, and the experimental results are shown in Table 1.
[0037] Table 1 Evaluation table of the surface treatment effects of the polishing solutions of Comparative Examples 1-2 and Examples 1-9 on 316L stainless steel
[0038] Table 1 shows that: the results of Comparative Example 1 indicate that when the content of the additive in the polishing liquid is insufficient, the surface brightness and flatness of the stainless steel will be significantly reduced due to excessive corrosion by the acid solution; the results of Comparative Example 2 show that too high an additive content will lead to insufficient polishing and it is difficult to achieve the best surface brightness and flatness. Within the quality range of the polishing liquid additive defined in the present invention, as the acid content and the additive content increase, the material removal rate and the etching amount of 316L stainless steel show an upward trend, while the surface roughness shows a law of increasing first and then decreasing; the surfaces of the specimens in all the examples show excellent flatness and brightness, indicating that within the quality range of the polishing liquid additive defined in the present invention, the polishing effect is stable and ideal. This result further verifies the rationality and effectiveness of the polishing liquid additive ratio in the present invention, and can achieve the best polishing effect in the surface treatment of 316L stainless steel. Using the polishing liquid prepared by the present invention to treat the surfaces of other metals can also achieve the beneficial effects described in the present invention.
[0039] In summary, the present invention realizes the full contact and uniform reaction between the polishing liquid and the stainless steel surface, thus significantly improving the product stability and polishing performance; specifically, the polishing liquid prepared by the present invention not only exhibits excellent metal removal rate, but also has a high production capacity and can meet the requirements of industrial production.
[0040] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.
Claims
1. A chemical polishing solution, characterized in that It is prepared by the following method: 1) Add them to a beaker according to the mass ratio of solvent A: oxidant: brightener: complexing agent of 100: 0.1 - 2: 0.1 - 2: 0.1 - 2, and ultrasonically disperse for 10 - 60 min at room temperature to obtain solution A; 2) Add them to a beaker according to the mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor of 100: 0.1 - 2: 0.1 - 2: 0.1 - 2, and ultrasonically disperse for 10 - 60 min at room temperature to obtain solution B; 3) Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 2 - 4: 1, and ultrasonically disperse for 15 - 25 min to obtain a pH regulator; 4) Add solution A, solution B, and the pH regulator to a beaker according to the mass ratio of 90 - 110: 90 - 110: 0.1 - 1, and ultrasonically disperse for 10 - 60 min at room temperature to obtain a chemical polishing solution.
2. The chemical polishing liquid according to claim 1, characterized in that In step 1): The mass ratio of solvent A: oxidant: brightener: complexing agent is 100: 0.5 - 1.5: 0.5 - 1.5: 0.5 - 1.5, preferably 100: 0.8 - 1: 0.8 - 1: 0.8 - 1; The ultrasonic dispersion time is 20 - 50 min, preferably 30 - 40 min of ultrasonic dispersion.
3. A chemical polishing solution according to claim 1, characterized in that In step 1): The solvent A is ethanol, and the solvent purity is chromatographic pure; The oxidant is at least one of hydrogen peroxide and sodium bisulfate, and the drug purity is chromatographic pure; The brightener is at least one of thiourea, salicylic acid, and sodium dodecylbenzenesulfonate, and the drug purity is chromatographic pure; The complexing agent is at least one of glycine and chitosan oligosaccharide, and the drug purity is chromatographic pure.
4. A chemical polishing solution according to claim 1, characterized in that In step 2): The mass ratio of solvent B: dispersant: defoamer: corrosion inhibitor is 100: 0.5 - 1.5: 0.5 - 1.5: 0.5 - 1.5; preferably 100: 1 - 1.2: 1 - 1.2: 1 - 1.2; The ultrasonic dispersion time is 20 - 50 min, preferably 30 - 40 min of ultrasonic dispersion.
5. A chemical polishing solution according to claim 1, characterized in that In step 2): The solvent B is DMF, and the drug purity is chromatographic pure; The dispersant is polyethylene glycol, and the drug purity is chromatographic pure; The defoamer is glycerol, and the drug purity is chromatographic pure; The corrosion inhibitor is sodium benzoate, and the drug purity is chromatographic pure.
6. A chemical polishing solution according to claim 1, characterized in that In step 3): Add hydrochloric acid and nitric acid to a beaker according to the mass ratio of 3: 1, and ultrasonically disperse for 20 min.
7. A chemical polishing solution according to claim 1, characterized in that In step 3): The hydrochloric acid and nitric acid are both of analytical purity.
8. A chemical polishing solution according to claim 1, characterized in that In step 4): Solution A, solution B, and the pH regulator are added according to the mass ratio of 100: 100: 0.2 - 0.8; preferably 100: 100: 0.4 - 0.6; The ultrasonic dispersion time is 20 - 50 min, preferably 30 - 40 min of ultrasonic dispersion.
9. Application of the chemical polishing solution as claimed in claim 1 in metal surface treatment.
10. Application of the chemical polishing solution as claimed in claim 9 in stainless steel surface treatment, especially in the surface treatment of 316L stainless steel.