JP2925876B2 - Metal surface oxidation treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for oxidizing a metal surface, and particularly relates to an apparatus for applying ultra-high vacuum, an ultra-clean gas line, an apparatus for producing biopharmaceutical materials, an apparatus for producing ultrapure water such as a substitute for chlorofluorocarbon. The present invention relates to a surface treatment method for a metal member used for a member.

[0002]

2. Description of the Related Art Recently, components such as an ultra-high vacuum application device, an ultra-clean gas line, a biopharmaceutical raw material production device, and an ultrapure water production device used for a substitute cleaning of chlorofluorocarbons, include
Stainless steel, which is excellent in heat resistance, corrosion resistance, and emission of impurity gas, is used.

[0003] Even in the case of stainless steel, if conventional surface processing such as electrolytic polishing is performed, gas components dissolved during scouring and adsorption and absorption during surface processing and storage are also considered.
May release occluded dust, gas, etc. In particular, in the electropolishing method of processing in water, the atomic gas component accompanying the electrolysis is dissolved and occluded in the metal, and the moisture is taken in the passive film of stainless steel formed in water, During use, there is a problem that moisture is continuously released for a long time, an ultra-high vacuum cannot be achieved, and a clean process gas is contaminated with moisture.

In order to solve such inconvenience, a stainless steel member is placed in a dry oxygen gas atmosphere containing a predetermined amount of ozone at a predetermined temperature (for example, about 150 to 300 ° C.) for a predetermined time (for example, about 150 ° C.). A surface treatment method for heating and performing an oxidation treatment to form an oxide film on the surface of a stainless steel member has been already proposed.

More specifically, a stainless steel member is heated as uniformly as possible in a heating chamber, and an oxygen gas containing ozone is supplied into the heating chamber to bring the oxygen gas into contact with the surface to be treated. As a result, the oxidation treatment was performed.

According to the above-mentioned surface treatment method, the oxide film formed on the surface becomes dense, and the elution amount of the impurity from the surface of the stainless steel member is extremely reduced, in combination with the action of oxidizing and removing impurities contained in ozone. Can be reduced.

[0007]

However, as described above, when oxidizing a stainless steel member with an oxygen gas containing ozone, the oxygen gas is brought into contact with the uniformly heated stainless steel member in the heating chamber. As a result, an oxide film is formed on the surface to be treated, but first, ozone is decomposed in a portion that comes into contact with the oxygen gas, and that portion is strongly oxidized, and therefore, a nonuniform oxidation is generated as a whole. Problem.

For example, when oxidizing the inner wall surface of a pipe member, the pipe member is heated uniformly, and oxygen gas containing ozone is supplied from one end side. Is decomposed, only this portion is strongly oxidized, and there is no ozone at the other end side, so that ozone oxidation is not performed.

Accordingly, an object of the present invention is to provide a metal surface oxidation treatment method capable of uniformly oxidizing the entire surface to be treated.

[0010]

In order to solve the above-mentioned problems, a first means of the present invention is to provide a metal member containing an acid containing ozone.
When an oxide film is formed on the surface by contacting elemental gas
Oxygen gas along the surface to be treated of the heated metal member.
Blows away from oxygen gas outlet
The temperature of the surface to be treated is increased in accordance with
Is a metal surface oxidation treatment method for forming

In order to solve the above-mentioned problems, a second means of the present invention is to contact an oxygen gas containing ozone with a metal member.
To form an oxide film on the surface.
Oxygen gas along the surface of the metal member
In addition, a metal surface oxidation treatment method in which an oxygen gas supply outlet is sequentially moved along a surface to be treated of a metal member.

According to a third aspect of the present invention, in order to solve the above-mentioned problems , an oxygen gas containing ozone is brought into contact with a metal member.
To form an oxide film on the surface.
Oxygen gas along the surface of the metal member
In addition, a metal surface oxidation treatment method for sequentially moving a heated portion of a metal member.

Further, in order to solve the above-mentioned problem, a fourth means of the present invention provides a method for forming an oxide film on the surface of a metal member by contacting the metal member with oxygen gas at a predetermined temperature. This is a metal surface oxidation treatment method in which the supply direction of oxygen gas is switched to the opposite direction on the way.

[0014]

According to the first means, a heated metal member is provided.
While blowing oxygen gas along the surface to be treated,
As the distance from the supply oxygen gas outlet increases,
Since the temperature of the surface treatment surface is set to be high , the thickness of the metal film formed on the surface of the metal member becomes substantially uniform throughout.

According to the second means, the heating means
Oxygen gas along the surface of the metal member
At the same time, the oxygen gas supply outlet is moved along the surface of the metal member to keep the ozone concentration at the oxidized portion constant, so that the thickness of the metal film formed on the surface of the metal member is reduced. Is substantially uniform throughout.

According to the third means, the heating means
Oxygen gas along the surface of the metal member
At the same time, by sequentially moving the heating portion of the metal member, the temperature of the oxidized portion is kept constant, so that the thickness of the metal film formed on the surface of the metal member is substantially uniform throughout. Become.

Further, according to the fourth means, even when the ozone concentration is changed, the thickness of the metal film formed on the surface of the metal member is reduced by switching the supply direction of the oxygen gas halfway. And is substantially uniform over the entire area.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In the first embodiment, a case where an oxide film is formed on the inner surface of a stainless steel piping member as a metal member will be described.

That is, as shown in FIG. 1, an oxygen gas a containing a predetermined amount of ozone is supplied from one end of a stainless steel piping member 1 along the surface to be treated toward the other end. The heating temperature of the pipe member 1 at this time is shown in FIG.
As shown by the solid line in the graph of FIG. 1, the ozone concentration of the oxygen gas a supplied to the inside of the pipe member 1 is gradually increased from one end to the other end as shown by the broken line in FIG. , Are sequentially lowered.

The concentration of the ozone drops naturally as it goes from the inlet side to the outlet side of the pipe member 1, that is, the self-decomposition progresses with the passage of time according to the temperature.

Therefore, as described above, by sequentially increasing the heating temperature from the inlet side to the outlet side,
Conversely, the ozone concentration decreases, and overall, the piping member 1
The thickness of the oxide film formed on the inner wall surface becomes uniform.

Here, the reason why the heating temperature and the ozone concentration are changed will be described in more detail as follows. That is, as shown in FIG. 3, the decomposition of ozone has a strong temperature characteristic, and when the temperature exceeds 300 ° C., the ozone is self-decomposed, so that the oxidizing effect of ozone cannot be expected. Therefore, the formed oxide film has a peak with respect to the temperature.

When the member to be processed is heated uniformly, as shown in FIG. 4, the ozone concentration changes over time, that is, between the inlet side and the outlet side. Therefore, the relationship between the time when the ozone concentration (C) is used as a parameter and the oxide film thickness is as shown in FIG. That is, when the oxidation time is constant, the oxide film thickness (A) to be formed is determined according to the ozone concentration (C).

Therefore, as shown in FIG. 6, when an oxide film having a uniform thickness (A) is formed on the surface of the member to be processed, a portion having a high ozone concentration (C) (for example, a pipe member) At the inlet side), the heating temperature (T) is maintained at a low temperature, and at a portion where the ozone concentration (C) is low (for example, in the case of a pipe member, at the outlet side), the heating temperature (T) is increased. Should be kept.

Further, a specific example will be described. A stainless steel pipe member (SUS316L, having a pipe diameter of 20 mm) is used.
A, When forming an oxide film on the inner wall surface of 2m length,
1 liter of oxygen gas containing 50,000 ppm ozone
Minutes, and the heating temperature is set to 200 on the inlet side.
When the temperature was maintained at 250 ° C on the outlet side, the variation in the thickness of the oxide film formed on the inner wall of the tube could be kept within 10%.

The temperature on the inlet and outlet sides is 250
When uniform heating was performed to reach ℃, the thickness variation of the oxide film exceeded 10%. Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, as shown in FIG. 7, a pipe member 11 made of stainless steel is uniformly heated to a predetermined temperature, and an ozone supply pipe 12
Is inserted, and oxygen gas a containing a predetermined concentration of ozone is blown out from the tip thereof along the surface to be processed , and the supply pipe 12 is sequentially moved along the inner wall surface as shown by arrow b. Is the way.

As described above, since the supply pipe 12 for supplying the oxygen gas a containing ozone to the inner wall surface of the pipe member 11 is moved along the inner wall surface, the concentration of ozone blown out to the inner wall surface is increased. Is constant, and the thickness of the oxide film formed on the inner wall surface is also uniform.

Here, a specific example will be described. A stainless steel pipe member (SUS316L, pipe diameter of 20 mm) is used.
A, when an oxide film is formed on the inner wall surface having a length of 2 m), a glass pipe having an outer diameter of 12 mm and an inner diameter of 8 mm is inserted into the inside of the pipe member, and a predetermined concentration is formed in the same manner as in the first embodiment. An oxygen gas containing ozone was blown out in a predetermined amount, and the glass pipe was moved at a speed of 1 cm / min to perform an oxidation treatment for 2 hours.

Also in this case, the variation in the thickness of the oxide film formed on the inner wall surface of the piping member could be kept within 10%. Next, a third embodiment of the present invention will be described.

In the above-described second embodiment, the oxidizing gas containing ozone is guided to the position where the oxidation treatment is performed. In the third embodiment, as shown in FIG. The ring heater 22 to be heated is moved at a predetermined speed, for example, in the direction of the arrow c, that is, the heated portion is moved.

Of course, during the heating , an oxidizing gas containing a predetermined concentration of ozone is introduced into the pipe member 21 along the surface to be processed.
Has been washed away. In this case, since only the portion to be treated is always maintained at a constant temperature, the variation in the thickness of the oxide film formed on the inner wall surface of the pipe member can be kept within a predetermined range.

Next, a fourth embodiment of the present invention will be described.
In the fourth embodiment, as shown in FIG.
The supply direction of the oxidizing gas a containing ozone to be supplied into the inside, that is, the flowing direction is switched midway. In FIG. 9, reference numeral 32 denotes a heater.

That is, first, as shown by the solid line in FIG. 9, the oxidizing treatment is performed while flowing the oxidizing gas a from one end to the other end, and after a lapse of a predetermined time, as shown by the broken line. Next, the oxidation treatment is performed while flowing the oxidizing gas a from the other end to the one end for a predetermined time.

As described above, by changing the flowing direction of the oxidizing gas containing ozone, the change in the thickness of the oxide film caused when the oxidizing gas flows in a certain direction is compensated for each other.
When viewed as a whole, the thickness of the oxide film to be formed can be made uniform.

[0036]

As described above, according to the first metal surface oxidation treatment method of the present invention, the oxygen gas containing ozone is contained in the metal member.
Contact to form an oxide film on the surface.
Oxygen gas is blown out along the surface of the heated metal member
And keep it away from the oxygen gas outlet
The temperature of the surface to be treated increases as
Therefore, the thickness of the metal film formed on the surface of the metal member can be made substantially uniform throughout.

According to the second metal surface oxidation treatment method, an oxygen gas containing ozone is brought into contact with the metal member.
To form an oxide film on the surface.
When oxygen gas is blown out along the surface of the metal member
In particular, since the supply outlet of the oxygen gas is sequentially moved along the surface to be processed of the metal member, the ozone concentration at the oxidized portion is kept constant, so that the oxygen gas is formed on the surface of the metal member. The thickness of the metal film can be made substantially uniform throughout.

According to the third metal surface oxidation treatment method, an oxygen gas containing ozone is brought into contact with the metal member.
To form an oxide film on the surface.
When oxygen gas is blown out along the surface of the metal member
In addition, the temperature of the oxidized portion is kept constant by sequentially moving the heated portion of the metal member, so that the thickness of the metal film formed on the surface of the metal member is substantially uniform throughout. Can be

Further, according to the fourth metal surface oxidation treatment method, even if the ozone concentration is changed, the metal film formed on the surface of the metal member can be changed by switching the supply direction of the oxygen gas in the middle. The thickness can be substantially uniform throughout. The oxide film thickness formed on the surface to be processed of the metal member can be made constant.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part for explaining a metal surface oxidation treatment method according to a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a distance from an inlet, a heating temperature, and an ozone concentration in the first embodiment.

FIG. 3 is a graph showing a relationship between a heating temperature, an oxide film thickness and an ozone concentration in the first embodiment.

FIG. 4 is a graph showing a relationship between time and ozone concentration when a heating temperature is used as a parameter in the first embodiment.

FIG. 5 is a graph showing the relationship between time and oxide film thickness when the ozone concentration is used as a parameter in the first embodiment.

FIG. 6 is a graph showing the relationship between the ozone concentration and the heating temperature when the thickness of the oxide film in the first embodiment is used as a parameter.

FIG. 7 is a sectional view of a principal part explaining a metal surface oxidation treatment method according to a second embodiment of the present invention.

FIG. 8 is a main part side view for explaining a metal surface oxidation treatment method according to a third embodiment of the present invention.

FIG. 9 is a main part side view for explaining a metal surface oxidation treatment method according to a fourth embodiment of the present invention.

[Explanation of symbols]

 a Oxidizing gas 1 Piping member 11 Piping member 21 Piping member 31 Piping member

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-274254 (JP, A) JP-A-63-310118 (JP, A) JP-A-3-134153 (JP, A) JP-A 55- 8441 (JP, A) JP-A-63-238259 (JP, A) JP-B-62-2624 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 8/06-8 / 34 C23C 10/06-10/16

Claims (4)

(57) [Claims] An oxygen gas containing ozone is brought into contact with a metal member.
To form an oxide film on the surface.
When oxygen gas is blown out along the surface of the metal member
In both cases, as the distance from the oxygen gas outlet increases,
A metal surface oxidation treatment method comprising forming a uniform oxide film by increasing the temperature of a treated surface . 2. An oxygen gas containing ozone is brought into contact with a metal member.
To form an oxide film on the surface.
When oxygen gas is blown out along the surface of the metal member
In both cases, a metal surface oxidation treatment method characterized by sequentially moving an oxygen gas supply outlet along a surface to be treated of a metal member. 3. An oxygen gas containing ozone is brought into contact with a metal member.
To form an oxide film on the surface.
When oxygen gas is blown out along the surface of the metal member
In both cases, the metal surface oxidation treatment method is characterized by sequentially moving a heated portion of the metal member. 4. An oxygen gas containing ozone is brought into contact with a metal member at a predetermined temperature to form an oxide film on the surface of the metal member. Characteristic metal surface oxidation treatment method.