JP2003147588A - Surface coating layer by iron and steel and surface treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment method for a surface coating layer by the iron and steel having a flat surface at an atomic level. SOLUTION: The surface coating layer having an electrochemically surface treated surface of <=10 nm in center line surface roughness Ra and <=30 nm in maximum height and having excellent flatness by the iron and steel having the excellent flat surface is subjected to surface cleaning to remove the dirt and oxidized film covering the surface by an electrochemical technique and is then immediately immobilized and the treatment conditions of a high passivation potential, a treating solution of a high temperature, long passivation holding time, and repetition of passivation and cathode reduction are combined, by which the surface is gradually reconstituted by the crystalline oxidized film and a step-terrace structure is formed. The surface flat at the atomic level in the terrace grown or expanded at this time is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a technique for improving corrosion resistance and improving surface flatness of steel used as a general structural material. The cleaner the surface of the steel base material, the easier the oxide film formed on the surface becomes to crystallize, but the present invention provides a flat (smoothed) surface at the atomic level by the electrochemical surface treatment, Thus, the present invention relates to a steel and a surface treatment method thereof, which can improve corrosion resistance as compared with a conventional rough surface and can reduce adsorption of gas and the like. The steel of the present invention means a material containing iron as a main component, which can be passivated, such as pure iron and stainless steel.

[0002]

2. Description of the Related Art A homogeneous and flat crystalline oxide film is formed on the surface of steel in order to improve the corrosion resistance of the steel or to prevent the adsorption of gases when the steel is used as a high vacuum container. Although necessary, this requires that the surface of the steel base material be smooth. Conventionally, as one of methods for obtaining a steel surface having excellent surface flatness, there has been proposed a method for producing a high-gloss steel by performing finish cold rolling using a smooth roll (Japanese Patent Laid-Open No. Hei 6).
-79611). However, although the surface roughness of steel in this technique is specified as Ra ≦ 1.0 μm, it is far from atomic level flatness, and it is hard to say that it has sufficient surface flatness. Further, a surface treatment method has been proposed in which the surface roughness Rmax is 1 μm or less by heat treatment in a low oxygen partial pressure atmosphere, or by bright drawing heat treatment after cold drawing (Japanese Patent Laid-Open No. 6-322512). WO9
5/28239). However, in these cases as well, the surface roughness Rmax is set to 1 μm or less, which is far from atomic level flatness.

On the other hand, in the wet passivation treatment, a treatment method has been proposed in which the corrosion resistance is improved by keeping the potential at 0.2 to 0.6 V of saturated calomel electrode standard in a sulfuric acid solution for 5 minutes or more ( JP-A-9-3655). However, this technique does not propose a method for treating stains and amorphous films formed after manufacturing, which is a key process for realizing atomic level planarization, and a transition process to passivation treatment. Further, conventionally, a method for expanding a flat terrace at the atomic level on the steel surface has not been described. For this reason, the development of a steel and a surface coating layer of steel with excellent flatness in terms of higher corrosion resistance and less gas adsorption and a surface treatment method for expanding a flat terrace at the atomic level. Is desired.

[0004]

SUMMARY OF THE INVENTION The present invention improves the flatness of the surface of a steel base material or the surface coating layer of steel to improve the properties of an oxide film formed on the surface of steel to improve corrosion resistance. Further, the present invention establishes a steel having a surface excellent in cleanliness with little adsorption of gas and dirt, and a method for manufacturing such a surface.

[0005]

The present invention further improves the corrosion resistance by improving the electrochemical surface treatment and expanding the terrace width of the surface coating layer of steel or steel with a step-terrace structure. It was found that it is possible to obtain steel as a structural material that can be made to have less gas adsorption. Based on this finding, the present invention provides 1) as an electrochemical treatment, immediately after removing a surface film or dirt at a base potential lower than -800 mV (saturated calomel electrode standard) in a solution for passivating steel. Potential is -300 to 1000m
In the surface treatment of the surface coating layer of the steel or the steel to be passivated by holding it at V, the surface treatment potential is held for 15 minutes (super) to 10 hours, and a wide terrace with a flat atomic level is characterized. The surface coating layer and surface treatment method with steel or steel with expanded thickness, 2) surface treatment potential of 70
The surface coating layer and the surface treatment with steel or steel having an expanded flat terrace at the atomic level according to the above 1), characterized in that the passivation treatment is carried out by holding at 0 to 900 mV (saturated calomel electrode standard). Method 3) As an electrochemical treatment, immediately after removing the surface coating or dirt at a base potential lower than -800 mV (saturated calomel electrode standard) in a solution for passivating steel, the surface treatment potential is -300 to 1000 m.
In the surface treatment of the surface coating layer of the steel or the steel to be passivated while being held at V, the solution temperature at the time of the passivation is set to a temperature in the range of room temperature (20 ° C) to 100 ° C. The surface coating layer and surface treatment method using iron or steel, which is characterized by expanding the area of flat terraces at the atomic level, and 4) the solution temperature at the time of passivation treatment is room temperature (20 °
C) to 100 ° C., the surface coating layer and surface treatment method using steel or steel having an expanded flat terrace at the atomic level according to the above 1 or 2, and 5) solution The temperature is set to a temperature in the range of 30 ° C to 100 ° C, and the surface coating layer and the surface treatment method using the steel or the steel having an expanded atomic level flat terrace as described in 3 or 4 above. ,I will provide a.

Further, the present invention further comprises 6) as an electrochemical treatment, -800 mV in a solution for passivating steel.
(Saturated calomel electrode standard) Immediately after removing the surface coating and dirt at a more base potential, the surface treatment potential was set to -300 to 100.
In the surface treatment of steel or a surface coating layer made of steel to be passivated by holding it at 0 mV, after the passivation treatment, the steel surface is kept in a lower humidity environment of less than 50% relative humidity. Surface coating layer and surface treatment method with steel or steel with expanded flat terrace area at a level, 7) After passivation treatment, the steel surface is kept in a lower humidity environment of less than 50% relative humidity And a surface coating layer and a surface treatment method using iron or steel having an expanded flat terrace at the atomic level according to each of the above 1 to 5, and 8) a solution for passivating the steel as an electrochemical treatment -800 mV (based on saturated calomel electrode)
Immediately after removing the surface coating and dirt with a more noble potential, in the surface treatment of the surface coating layer of steel or steel in which the surface treatment potential is held at -300 to 1000 mV for passivation, the cathode reduction step and the cathode reduction step are not performed. A surface coating layer and a surface treatment method using steel or steel with an expanded flat terrace at the atomic level, characterized by repeating the passivation treatment step, and 9) repeating the cathode reduction step and the passivation treatment step. The present invention also provides a surface coating layer and a surface treatment method using steel or steel in which the width of a terrace that is flat at the atomic level is expanded, as described in each of 1 to 7 above.

The present invention further provides 10) as a solution for passivating steel, boric acid, perchloric acid, acetic acid, nitric acid,
The passivation treatment is performed using one type of solution selected from sulfuric acid, phosphoric acid, oxalic acid, chromic acid, hydrofluoric acid, or a mixed solution of two or more types or a solution containing 50% or more thereof. 1) A surface coating layer and a surface treatment method using iron or steel having an expanded flat terrace at the atomic level according to 1) to 9), 11) the center line surface roughness Ra is 10 nm or less, and / or the maximum height. Rmax is 30n
The surface coating layer and the surface treatment method using iron or steel having an expanded terrace area flat at the atomic level according to each of 1 to 10 above, which has an electrochemically treated surface of m or less, 12) The center line surface roughness Ra is 1 nm or less and / or the maximum height Rmax is 3 nm or less, and the steel or steel having expanded atomic-level flat terraces according to each of claims 1 to 10. Surface coating layer and surface treatment method according to 13), which is a coating layer coated with a sputter deposit, and is made of steel or steel having an expanded flat terrace at the atomic level according to each of 1 to 12 above. A surface coating layer and a surface treatment method are provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies on the electrochemical treatment method, the present inventors have found that after removing the dirt and amorphous oxide film covering the steel surface, it is passed through another potential. Immediately, and then gradually reconstitutes the oxidized surface to form a uniform and dense step-terrace structure, which leads to an atomically flat surface on the terrace. I got it successfully.

That is, the removal of the amorphous oxides, hydroxides and stains formed after the steel production makes it possible to highly purify the oxide film formed when the passivation potential is maintained. There is. The oxide film containing no impurities is 50
Moisture can be eliminated and crystallized in a lower humidity environment of less than%, forming an atomically flat surface. The surface state was confirmed by observing an atomic image with a scanning tunneling microscope described below.

Due to dirt and deposits on the surface of steel, water is always retained there, and rust is generated from such places. As in the case of the treatment method of the present invention, the amount of irregularities on the surface serving as the adsorption site can be remarkably reduced on a surface that is flat at the atomic level compared to before treatment. Keep the steel surface clean by reducing dirt and adsorption,
It contains a very effective method of improving the corrosion resistance.

The outline of the flattening method of the present invention comprises the following steps. (1) Mechanical polishing step (2) Surface cleaning treatment step (3) Passivation treatment step immediately after the above step By this, an atomic level flat surface can be obtained on steel.

Next, each of the above steps will be described in detail. In the mechanical polishing step (1), for example, # 2
After polishing by using some combination of water-resistant abrasive papers of 50 to # 3000, 1 μm or less, preferably 0.25
Buffing is performed using a diamond paste of μm. After that, degreasing cleaning is performed in ethyl alcohol, propyl alcohol, or acetone using an ultrasonic cleaning machine to perform sufficient cleaning. In a material having a coating layer formed by spatter deposits or the like, since the coating layer itself already has a smooth surface equal to or more than the polishing surface, this mechanical polishing step is unnecessary,
Mainly used for bulk materials such as plate materials.

Next, in the step (2) of the surface cleaning treatment, in a solution in which a steel material causes a passivation phenomenon, for example, a boric acid solution, at a base potential lower than -800 mV (saturated calomel electrode standard), By holding the film in the cathode region for 5 minutes or more, the amorphous film and surface stains are cathode-reduced and removed to achieve surface cleaning. This process is a uniform and precise step on the steel surface of the present invention.
It is an important step to form a terrace structure and achieve an atomically flat surface on the terrace.

In the passivation treatment step (3), after the cleaning treatment, the passivation potential is immediately maintained for 16 minutes or more without passing through any potential other than the passivation region. The holding potential at this time is held in the passive state region of the steel, that is, the potential of -300 to 1000 mV, preferably the noble potential (700 to 900 mV). After a while after the treatment of (3), the oxide film formed by the passivation is crystallized and a flat surface at the atomic level can be obtained. The structural stability of the film differs depending on the passivation potential. At low potential, the film density is low, and as the potential increases, the film density increases. Furthermore, when the potential becomes higher than 250 mV, a two-dimensional structure starts to change to a three-dimensional structure, and at 700 mV or more, the structure becomes a double or triple structure, and the film becomes thick and large particles are formed. Above it becomes a large terrace, ie the terrace can be expanded more.

In particular, the surface treatment potential is kept for 15 minutes (over)
By holding for 10 to 10 hours, it is possible to obtain a surface coating layer made of steel or steel in which the area of the terrace that is flat at the atomic level is expanded. When it is kept at the passivation potential, the current sharply drops, and when it exceeds 15 minutes, it shows a substantially stable current value. At this time, the film starts to form like islands, the area gradually expands, and eventually the whole surface is covered. When the whole surface is covered, the current value becomes almost constant. However, when observed in detail, the current value gradually decreases slightly. At this stage, the longer the treatment time is, the lower the current value is, the thick passivation film is formed, and the large terrace is also generated by the reconstruction. However, if the treatment time is too long, a porous film will be produced, so it is necessary to adjust the treatment time to be suitable for expanding the terrace width. It is appropriate that the passivation treatment time be kept within 10 hours.

The solution temperature during the passivation treatment is room temperature (2
It is desirable to set the temperature in the range of 0 ° C) to 100 ° C. Moreover, after the passivation treatment, the relative humidity of the steel surface is 50
By holding in a lower humidity environment of less than%, a surface with a more suitable terrace can be obtained. The passivity maintaining current density differs depending on the processing temperature, and the higher the temperature, the larger the current density. As the current density increases, the passive film becomes thicker and the particle size also increases, so the terraces that make up the particles also become wider. In particular, as the passivation treatment potential is higher, the current density is significantly increased even with a slight temperature increase. From this, the solution temperature at the time of passivation treatment is preferably 30 ° C. or higher. After the passivation treatment in the solution, if the humidity is high, the potential rapidly returns to the natural immersion potential. After the passivation treatment, several hours are required for the surface structure to be reconstructed, and during that time, a low humidity environment is required to suppress the potential drop due to the adsorbed water. Therefore, after the passivation treatment of the steel surface,
It is desirable to maintain a low humidity environment of less than 50% relative humidity.

In the cathode reduction step and the passivation step, a surface coating layer made of steel or steel having a flat terrace area expanded at the atomic level can be obtained even once. Further, it is possible to more stably obtain the steel or the surface coating layer of the steel with the expanded area of the terrace. Bulk materials are usually much more difficult to flatten than cover materials. Therefore, repeated reduction-passivation is extremely effective for bulk materials. Also, especially S
It is effective for passivation treatment of US430.

As described above, flatness at the atomic level can be confirmed by observing an atomic image with a scanning tunneling microscope. At this time, the centerline average roughness Ra on the terrace is 10 nm or less and / or the maximum height Rmax.
Can be 30 nm or less. The center line average roughness Ra is 10 nm or less, and the maximum height Rmax is 30 n.
The reason for setting m or less is that atomic level flatness can be expected. Preferably, the centerline average roughness Ra on the terrace is 1 nm or less and / or the maximum height Rmax is 3 nm.
The following is recommended.

Although the following examples are explained using specific steels, the present invention can naturally be applied to steels and stainless steels other than these examples and have the same actions and effects. Further, as the passivation solution, a solution that makes steel passivated, that is, boric acid, perchloric acid, acetic acid,
The present invention is naturally applicable to nitric acid, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, hydrofluoric acid, and a mixed solution of at least two or more of these, or a solution containing 50% or more of them, and the same action and Have an effect. Further, the steel which can be used in the present invention is not only a bulk material such as a steel plate, but also a coating layer having the same composition as the steel, a physical vapor deposition method such as a sputter deposit, a chemical vapor deposition method, etc. It is also applicable to a material having a coating layer formed on a bulk material) or other metal or ceramics.

The steel which can be used in the present invention means a material containing iron as a main component, from pure iron to stainless steel. In addition, since it is premised that passivation can be performed, materials such as carbon steel that are not passivated are naturally excluded. In the present invention, it is particularly effective for pure iron and stainless steel (iron-12% chrome steel, etc.). For example, for the structure or material of an apparatus or instrument that cannot be mechanically polished, a coating layer having the same composition as steel is formed by sputter depositing, etc., and a surface treatment is performed by the method of the present invention, and the properties of the oxide film are Can improve the corrosion resistance, and can be a material having a surface excellent in cleanliness with less adsorption of gas and the like. In any case, there is a problem of steel or a surface having a surface coating layer of an equivalent component, and if the conditions of the present invention can be achieved, the same action and effect will be obtained.

An example of a scanning tunneling microscope observation of the steel surface treated by the present invention is shown in FIGS. 9 in FIG.
A surface coating layer was formed by sputter depositing 9.9% of iron on a substrate, and this was subjected to the treatment of the present invention. In this case, the center line average roughness Ra on the surface is 0.06 nm, and the maximum height Rmax is 0.31 nm.
Met. A step-lates structure has been observed. In FIG. 2, similarly, a surface coating layer was formed by sputter depositing 99.9% iron on the substrate, and the surface treatment layer was subjected to the treatment of the present invention. In this case, the centerline average roughness Ra is 0.03 nm, and the maximum height Rmax is 0.18 nm.
Met. Since the atomic image is visible, it is clearly observed that it has atomic level flatness.

[0022]

EXAMPLES AND COMPARATIVE EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. That is,
Of course, other examples, modes, modifications and the like within the scope of the technical idea of the present invention are included.

(Example 1) A plate material of 99.9% pure iron was used as a test material. This is # 400, # 600, # 10
00, # 1500 water resistant polishing paper and 0.25 μm diamond paste were mechanically polished, and then ultrasonically cleaned in ethyl alcohol, isopropyl alcohol and acetone for 3 minutes each. Next, in a boric acid solution, for 5 minutes to -1100 mV based on a saturated calomel electrode,
-1500 mV for 5 minutes, -1100 mV for 30 minutes,
Hold each. Immediately after that, the sample was kept at +400 mV for 30 minutes, washed with water, and kept in the atmosphere.
The solution temperature during the passivation treatment is 60 ° C,
After the passivation treatment, the relative humidity of the pure iron surface was maintained in a low humidity environment of 30%. Pure iron obtained by this,
As a result of observing the surface structure and atomic image with a scanning tunneling microscope, a step-lates structure and atomic level flatness were observed. Further, the center line average roughness Ra at this time
Was 0.1 nm and the maximum height Rmax was 2.3 nm. Further, the surface-treated product of Example 1 is
Corrosion resistance is improved by 20% or more compared with the conventional one.

(Example 2) A pure iron-coated silicon substrate, which was sputtered with a target of 99.9% pure iron and laminated for several hundred nm on a silicon substrate, was used as a test material. In this case, mechanical polishing is not performed. Next, this was ultrasonically cleaned in acetone for 1 minute, and then in a boric acid solution for 5 minutes at -1100 mV based on a saturated calomel electrode, at -1500 mV.
For 15 minutes and -1100 mV for 15 minutes. Immediately after that, it was held at +750 mV for 15 minutes. The solution temperature during the passivation treatment is 35 ° C.
After the passivation treatment, the relative humidity of the pure iron surface is set to 4
It was kept in a low humidity environment of 0%. The surface structure changed gradually, and the atomic image could be observed with the scanning tunneling microscope. The surface roughness at this time is 0.03 nm in terms of center line average roughness Ra,
The maximum height Rmax was 0.18 nm.

(Example 3) Stainless steel (JIS standard S
A plate material of US430) was used as a test material. this,#
It was mechanically polished using 400, # 600, # 1000, # 1500 water resistant abrasive paper and 0.25 μm diamond paste, and then ultrasonically cleaned in ethyl alcohol, isopropyl alcohol and acetone for 3 minutes each. Next, in a sulfuric acid solution, -1000 mV for 5 minutes, -1500 mV for 3 seconds, based on a saturated calomel electrode,
It was held at −1000 mV for 2 minutes and −800 mV for 1 minute, respectively (cathode reduction treatment). Immediately after that +40
Hold at 0 mV for 15 minutes (passivation treatment), then wash with water,
This was kept in the atmosphere for 1 hour or more. The solution temperature during the passivation treatment was 25 ° C. The relative humidity of the stainless steel surface at this time was 50%. Again, the cathode reduction treatment and the passivation treatment were performed. The surface structure and atomic image of the stainless steel obtained by repeating the above two treatments were observed by a scanning tunneling microscope, and as a result, a step-lates structure and atomic level flatness were observed. The center line average roughness Ra at this time is 0.09 nm, and the maximum height Rmax is 0.5.
It was 5 nm.

(Comparative Example 1) A steel coated silicon substrate having a thickness of 150 nm laminated on a silicon substrate was used as a test material. in this case,
Mechanical polishing was not carried out as in the case of Example 2. Next, this was ultrasonically cleaned in acetone for 1 minute, and then in a boric acid solution at -1100 mV for 5 minutes, -1500 mV for 15 minutes, and -1100 mV for 15 minutes in a saturated calomel electrode standard.
Hold for minutes. After that, the potential was held at -600 mV for 15 minutes. In this case, since the potential was kept slightly lower than the potential at which a stable passive film was formed, the growth of oxides did not occur much on the surface of the test material, and it was difficult to observe the atomic image. As described above, those which do not satisfy the conditions of the present invention have a problem that a uniform oxide film is not formed on the surface of steel and lacks flatness. Further, at this time, the same degree of improvement in corrosion resistance as in Example 1 was not recognized.

[0027]

INDUSTRIAL APPLICABILITY The present invention improves the flatness of a steel or steel surface coating layer, thereby improving the properties of an oxide film formed on the surface of the steel or steel surface coating layer to improve corrosion resistance. In addition, it has a surface excellent in cleanliness with little adsorption of dirt and the like. As a result, when used in a vacuum container, for example, there are few gas adsorption sites on the inner wall of the vacuum container, a high vacuum can be reached quickly, and a higher vacuum environment can be obtained. Also, since it can be applied to a surface coating layer such as a sputter deposit, the surface coating layer made of steel is formed by using a material such as steel or other metal or ceramics as a substrate,
It has a remarkable characteristic that the same effect as described above can be obtained.

[Brief description of drawings]

FIG. 1 is an observation example of a scanning tunneling microscope of a steel surface, showing a step-lates structure when steel is sputter deposited on a substrate and a surface film is formed by a passivation treatment.

FIG. 2 is an observation example of a scanning tunneling microscope of a steel surface, showing an atomic image on a terrace when the steel is sputter-deposited on a substrate and a surface film is formed by passivation treatment.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Michio Yoneya             4-2-1 Gotake, Miyagino-ku, Sendai City, Miyagi Prefecture               AIST Tohoku Center (72) Inventor Ikuo Ishikawa             4-2-1 Gotake, Miyagino-ku, Sendai City, Miyagi Prefecture               AIST Tohoku Center (72) Inventor Hui Hoa Den             405, 10-2 Engaigaoka, Miyagino-ku, Sendai City, Miyagi Prefecture             Issue room

Claims (13)

[Claims] 1. As an electrochemical treatment, -800 mV (based on a saturated calomel electrode) in a solution for passivating steel.
Immediately after removing the surface coating and dirt with a more noble potential, the surface treatment potential is set to 15 in the surface treatment of the steel or the steel for performing the passivation treatment while maintaining the surface treatment potential at -300 to 1000 mV. A surface coating layer and a surface treatment method using iron or steel having an expanded flat terrace at the atomic level, which is held for 10 minutes (ultra) to 10 hours. 2. A steel plate with an expanded flat terrace at the atomic level according to claim 1, characterized in that the passivation treatment is carried out by maintaining the surface treatment potential at 700 to 900 mV (saturated calomel electrode standard). Or a surface coating layer and surface treatment method using steel. 3. As an electrochemical treatment, -800 mV (based on saturated calomel electrode) in a solution for passivating steel.
Immediately after removing the surface coating or dirt with a more base potential, the passivation treatment is carried out in the surface treatment of the steel or the surface coating layer of the steel, which holds the surface treatment potential at -300 to 1000 mV. The solution temperature to room temperature (20 °
C) to 100 ° C. A surface coating layer and a surface treatment method using steel or steel having an expanded flat terrace at the atomic level, which is characterized in that the temperature is in the range of 100 ° C. 4. The atomic level flat terrace according to claim 1 or 2, wherein the temperature of the solution during the passivation treatment is set to a temperature in the range of room temperature (20 ° C) to 100 ° C. A surface coating layer and a surface treatment method using steel or steel having an expanded width. 5. The steel or steel with an expanded atomically flat terrace according to claim 3 or 4, wherein the solution temperature is in the range of 30 ° C to 100 ° C. Surface coating layer and surface treatment method. 6. As an electrochemical treatment, -800 mV (based on saturated calomel electrode) in a solution for passivating steel.
Immediately after removing the surface coating and dirt at a more base potential, in the surface treatment of the surface coating layer of steel or steel that holds the surface treatment potential at -300 to 1000 mV for the passivation treatment, after the passivation treatment, A surface coating layer and a method of surface treatment with steel or steel with an expanded atomically flat terrace, characterized in that the steel surface is kept in a lower humidity environment of less than 50% relative humidity. 7. After the passivation treatment, the steel surface is subjected to a relative humidity of 5
Maintaining a lower humidity environment of less than 0%, the surface coating layer and the surface treatment method with steel or steel with an expanded atomic level flat terrace according to each of claims 1 to 5. 8. As an electrochemical treatment, -800 mV (based on saturated calomel electrode) in a solution for passivating steel.
Immediately after removing the surface coating and dirt with a more noble potential, in the surface treatment of the surface coating layer of steel or steel in which the surface treatment potential is held at -300 to 1000 mV for passivation, the cathode reduction step and the cathode reduction step are not performed. A surface coating layer and a surface treatment method using iron or steel with an expanded flat terrace at the atomic level, characterized by repeating the activation treatment step. 9. A surface coating layer made of steel or steel having an expanded flat terrace at the atomic level according to each of claims 1 to 7, wherein the cathode reduction step and the passivation treatment step are repeated. And surface treatment method. 10. A solution for passivating steel is boric acid, perchloric acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, oxalic acid,
The passivation treatment is performed by using one type of solution selected from chromic acid and hydrofluoric acid, a mixed solution of two or more types, or a solution containing 50% or more thereof.
To the surface coating layer and the surface treatment method using steel or steel in which the width of the terrace that is flat at the atomic level is expanded. 11. An atomically flat surface according to claim 1, which has an electrochemically treated surface having a centerline surface roughness Ra of 10 nm or less and / or a maximum height Rmax of 30 nm or less. Coating layer and surface treatment method using steel or steel with an expanded terrace area. 12. The atomic level flat terraces according to each of claims 1 to 10, wherein the center line surface roughness Ra is 1 nm or less and / or the maximum height Rmax is 3 nm or less. Surface coating layer and surface treatment method with expanded steel or steel. 13. A surface coating layer and surface made of steel or steel with an expanded flat terrace at the atomic level according to each of claims 1 to 12, which is a coating layer coated with a spatter deposit. Processing method.