KR20070088516A - Method of surface treatment - Google Patents

Abstract

Any matter of chemical liquid, metal, etc. adhering to the surface of a member as a constituent of vacuum treatment apparatus, such as a vacuum vessel, is removed without the use of highly dangerous nitric acid, etc. There is provided a method of surface treatment for a metal part being a constituent of vacuum treatment apparatus as a treatment object, characterized in that the treatment object on its surface is first subjected to electrolytic polishing, partial electrolytic polishing, chemical polishing, pickling or electrolytic pickling and thereafter washed by means of an alkali chelate solution obtained by adding a carboxylic acid or carboxylic salt to a 0.5 to less than 3 wt.% dilute alkali solution up to a concentration of 0.5 to less than 10 wt.%.

Description

Surface treatment method {METHOD OF SURFACE TREATMENT}

TECHNICAL FIELD This invention relates to the surface treatment method for cleaning the surface of the metal component which comprises a vacuum processing apparatus.

The stainless steel member constituting the vacuum processing device such as a vacuum container is welded, machined, or the like, and formed into a shape of a vacuum container, and then subjected to surface treatment in order to remove lubricants, fingerprints, and the like attached during processing. I'm trying to.

In recent years, since the vacuum apparatus has been enlarged and it has become difficult to process all the members constituting the enlarged vacuum processor at once, the present applicant has proposed partial electrolytic treatment in Japanese Patent Application 2004-219001.

Also in this partial electrolytic treatment, cleaning with pure water or the like is necessary to remove the chemical liquid used for the treatment. In the process of partial electrolytic treatment, metallic deposits called smuts (in the case of stainless steel, oxides and salts such as Cr, Ni, Fe, etc. are unevenly attached) are purely cleaned using a high pressure jet. It is difficult to remove even if it is, and there is a problem that the metallic deposit is released into the space under a vacuum atmosphere, or charged particles are released into the space during subsequent film formation, which may contaminate the vacuum apparatus. In order to remove such metallic deposits, there has been a problem that after partial electrolytic treatment, cleaning is performed using nitric acid having a high risk of handling.

As the surface treatment method of the apparatus, in addition to the partial electrolytic treatment described above, electrolytic polishing, chemical polishing and the like that have been conventionally performed, all of these methods adhere to the metal surface described above after the treatment. Leaving the smut as it was, there was a problem of being released into the space and contaminating the vacuum apparatus as in the case of partial electrolytic treatment. In addition, in order to remove such metallic deposits, there has been a problem that after partial electrolytic treatment, cleaning is performed using nitric acid having a high risk of handling.

Accordingly, the present invention is to solve the above-mentioned conventional problems, and does not use a high-risk nitric acid or the like for chemical substances or metals attached to the surface of the members constituting the vacuum processing apparatus such as a vacuum container. Moreover, it aims at removing without immersion.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, as a result of earnestly examining, the present inventors discovered the following solution means based on the point that the said subject can be solved by using an alkaline chelating liquid instead of nitric acid.

That is, the surface treatment method of this invention is a surface treatment method using the metal component which comprises a vacuum processing apparatus as a to-be-processed object as described in Claim 1, The surface of the said to-be-processed object is electropolishing, partial electrolytic treatment, chemical After polishing, pickling, or electrolytic pickling, to an alkaline chelate solution obtained by adding carboxylic acid or carboxylic acid so as to have a concentration of 0.5% by weight to less than 3% by weight so as to have a concentration of 0.5% by weight to less than 10% by weight. By this, the surface of the to-be-processed object is wash | cleaned.

The surface treatment method according to claim 2 is characterized in that, in the surface treatment method according to claim 1, the temperature of the alkali chelate liquid is set to 10 to 80 ° C.

According to the surface treatment method of this invention, the surface of a to-be-processed object can be wash | cleaned with a comparatively simple structure. Further, since deposits such as metal on the surface of the workpiece can be removed without using nitric acid, there is little risk. In addition, if the vacuum treatment apparatus is constituted by the member surface-treated according to the present invention, it is possible to reduce the gas emitted in a vacuum atmosphere.

1 is a graph showing a change in gas release rate per unit area of Example 3

[Description of the code]

1: gas release rate per unit area of sample treated with chelating liquid

2: gas release rate per unit area of the sample which was not treated with chelating liquid

The present invention is a surface treatment method of using a metal component constituting a vacuum treatment apparatus as a workpiece, after the surface of the workpiece is subjected to electropolishing, partial electrolytic treatment, chemical polishing, pickling or electrolytic pickling, at least 0.5% by weight. The surface of the object is washed with an alkaline chelating solution obtained by adding carboxylic acid or carboxylic acid to a concentration of less than 3% by weight of the rare alkaline solution so that the concentration is 0.5% by weight to less than 10% by weight. It is to be done.

The metal component which comprises the said vacuum processing apparatus will not be restrict | limited in particular, if it is a component in a vacuum processing environment. As an example, a metal container etc. are mentioned. On the other hand, as said metal, stainless steel, an aluminum alloy, a titanium alloy etc. are mentioned.

As the treatment medium, if the current can flow between the electrodes, the material and the shape are not limited. For example, a nonwoven fabric can be used.

The electrolytic polishing, chemical polishing, pickling or electrolytic pickling is well known, and the partial electrolytic treatment is to connect the workpiece to the anode side of the power supply, and to attach the electrolyte solution to the surface of the workpiece on the cathode side. Electrolytic polishing of the surface of the workpiece by connecting a treatment medium for contact and passing a DC current through the electrolyte between the electrodes, and by this treatment, surface roughness (R _max ) of the workpiece is determined. It is more preferable to set it as 0.1 micrometer. In addition, the specific example is described in Japanese patent application 2004-219001.

The electrolytic solution used for the electropolishing or partial electrolytic treatment contains at least one of an inorganic acid, an organic acid, an inorganic acid salt and an organic acid salt. Specifically, phosphoric acid, sulfuric acid, ammonium citrate, ammonium chloride, ammonium dihydrogen phosphate, Ammonium sulfate, sodium nitrate, citric acid and the like.

In addition, as a processing medium which can be used for partial electrolytic treatment, if a direct current can flow between the electrodes, the material and shape are not limited, but a nonwoven fabric can be used, for example.

The electrolytic current density in the electropolishing or partial electrolytic treatment varies depending on the object to be treated, but is, for example, 0.1 to 0.5 A / cm 2 if it is stainless steel.

As an alkaline chelate liquid, the solution which added citric acid, sodium citrate, ammonium oxalate, sodium phthalate, potassium tartrate, sodium gluconate, malic acid, etc. to dilute alkaline aqueous solution, such as sodium hydroxide, etc. are mentioned.

It is preferable that the said alkali chelate liquid shall be 10 degreeC-80 degreeC. It is because when it is less than 10 degreeC, reaction rate will fall remarkably, and when it exceeds 80 degreeC, handleability will be bad and there exists a possibility of alkali corrosion.

In addition, the treatment with the alkali chelate solution is preferably carried out by infiltration into a treatment medium such as cloth. This is because the surface treatment can be performed locally even if the workpiece is enlarged.

Example 1

Partial electrolytic treatment was carried out on the SUS304 (300 mm x 150 mm x 1 mm) to be treated with neutralized salts of sodium dihydrogen phosphate and sodium nitrate. The following treatment was performed by.

a) A solution in which sodium citrate is added to 1% by weight of sodium hydroxide solution so that the concentration is 3% by weight.

b) A solution in which 1% by weight of sodium hydroxide solution is added with malic acid so that the concentration is 3% by weight.

Each chelating solution was added at a temperature of 40 to 50 ° C, contained in a cleaning cloth, and the entire surface of the object was wiped. After the completion of wiping, high-pressure jet cleaning was performed with pure water heated to 50 ° C to remove the chemical liquid and alkaline chelate solution used for electrolytic polishing. And it dried with the liquid nitrogen vaporized as finishing.

In order to confirm the effect of smut removal, ion chromatography analysis was performed. Specifically, the object was treated before and after washing, and after wiping the entire surface with a cleaning cloth infiltrated with pure water, 100 ml of pure water permeated into the cleaning cloth was extracted to calculate the amount of each ion per unit area. .

This result is shown in Table 1 about a and Table 2 about b.

(ngcm2) Cation Na ⁺ NH ₄ ⁺ K ⁺ Mg ^{2 +} Ca ^{2 +} NaH ₂ PO ₄ Before removal 25.1 26.7 19.6 ND 22.1 After removal 1.7 1.8 0.2 ND ND NaNO ₃ Before removal 33.1 35.9 22.7 ND 34.2 After removal 1.5 0.5 0.1 ND ND

(ngcm2) Negative ion F ^- Cl ^- NO ₂ ^- Br ^- NO ₃ ^- PO ₄ ^{3 -} SO ₄ ^{2 -} NaH ₂ PO ₄ Before removal 78.9 39.4 77.2 12.4 682.3 247.2 332.5 After removal 0 1.3 3.7 ND 1.3 4.9 2.6 NaNO ₃ Before removal 77.3 34.1 789.5 22.7 542 324.1 246.1 After removal 1.8 3.7 7.6 ND 5.3 1.9 3.8

(ngcm2) Cation Na ⁺ NH ₄ ⁺ K ⁺ Mg ^{2 +} Ca ^{2 +} NaH ₂ PO ₄ Before removal 19.1 18.7 22.6 ND 27.1 After removal 2.8 12.2 0.7 ND ND NaNO ₃ Before removal 32.1 21.9 11.9 ND 23.1 After removal 1.9 2.8 0.4 ND ND (ngcm2) Negative ion F ^- Cl ^- NO ₂ ^- Br ^- NO ₃ ^- PO ₄ ^{3 -} SO ₄ ^{2 -} NaH ₂ PO ₄ Before removal 85.9 33.3 74.2 17.4 789.1 251.6 348 After removal 0 1.9 4.7 ND 1.9 6.9 1.6 NaNO ₃ Before removal 57.3 19.9  54.7 11.6 967.1 104.5 127.5 After removal 2.1 4.1 5.5 ND 6.3 2.5 1.8

From the said Table 1 and Table 2, after a smut removal, the cation of Na <^+> also became few with the anion used as an adhesion salt of an alloying component compared with before removal.

Example 2

The SUS304 (300 mm x 150 mm x 1 mm) was subjected to partial electrolytic treatment with neutralized salts of sodium dihydrogen phosphate and sodium nitrate, and the following two kinds of chelates were applied to the red and blue smuts formed on the surface. The following treatment was performed with the liquid.

a) A solution obtained by adding sodium citrate to a concentration of 3% by weight in a 1% by weight sodium hydroxide solution at 40 ° C

b) A solution in which 1% by weight of sodium hydroxide solution humidified at 40 ° C. is added malic acid so that the concentration is 3% by weight.

About the chelating liquid of a, b, it included in the washing cloth and wiped the whole surface of to-be-processed object. After the end of wiping, in order to confirm the effect of removing the smut, each used cleaning cloth was immersed in 100 ml of pure water, and the amount of elution of the metal component in each chelate solution was extracted into the pure water. The metal to be analyzed was measured by atomic absorption analysis as Fe, Cr, and Ni as components of the stainless alloy.

On the other hand, in order to show that the detected stainless steel component is from the smut portion and not from the stainless steel itself, the smut is removed by 30% by weight of nitric acid solution, after washing with water, and then treated by a, followed by the treatment by a. A sample extracted from the cleaning cloth used for was prepared, and this was referred to as c.

This result is shown in Table 3.

a (mg / L) b (mg / L) c (mg / L) Fe Cr Ni Fe Cr Ni Fe Cr Ni NaH ₂ PO ₄ 1.42 0.06 ND 1.18 ND ND ND ND ND NaNO ₃ 1.33 0.08 ND 1.67 0.07 ND ND ND ND

From the above results, Fe and Cr were detected from the cleaning cloth using a and b. On the other hand, in c, the element which comprises stainless steel of Fe, Cr, and Ni was not detected.

From this result, it turned out that a, b removes a smut, without damaging the to-be-processed object itself.

Example 3

Partial electrolytic treatment was carried out with a neutralized salt of ammonium dihydrogen phosphate and sodium nitrate to the treated material of SUS304 (300 mm × 150 mm × 1 mm), and sodium citrate was dissolved in 1% by weight of sodium hydroxide solution so that the concentration was 3% by weight. Was added to the cleaning cloth so as to infiltrate the cleaning cloth to evaluate the gas release characteristics of the wiping and the non-wiping.

The gas release characteristic was evaluated by the change of the gas release rate per unit area discharged during the temperature increase from room temperature to 500 degreeC using the temperature release method.

1 is a diagram showing a change in gas release rate per unit area, in which 1 is a gas release rate of a sample treated with a chelating liquid, and 2 in the figure is a gas release rate of a sample not treated. to be.

As shown in Fig. 1, the sample treated with the chelating liquid has a lower gas discharge rate especially at a temperature of 250 ° C or higher as compared with the sample which has not been treated. The source of gas released in this temperature range was removed by treatment with a chelating liquid.

Example 4

The SUS304 (300 mm x 150 mm x 1 mm) was subjected to electropolishing treatment with 70% phosphoric acid and 30% sulfuric acid solution, and the following treatment was performed with one of the following chelate liquids on the smut formed on the surface. Was carried out.

a) A solution of sodium citrate added to 1% sodium hydroxide solution so that the concentration is 3%.

The said chelating liquid was added at 40 degreeC-50 degreeC, it contained in the clean cloth, and wiped the whole surface of to-be-processed object. After the wiping was completed, high-pressure jet washing using pure water heated to 50 ° C was carried out to remove the chemical liquid and the alkaline chelate solution used for electropolishing. It dried with the liquid nitrogen vaporized as a finish.

In order to confirm the effect of smut removal, ion chromatography analysis was performed. Specifically, the object to be treated before and after washing, and wipe the whole surface in a clean cloth infiltrated with pure water, and then extract 100ml of pure water permeated into the clean fabric to calculate the amount of each ion per unit area It was. The results are shown in the table.

Cation Na ⁺ NH ₄ ⁺ K ⁺ Mg ^{2 +} Ca ^{2 +} Before removal 30.2 23.8 18.6 ND 25.4 After removal 1.4 0.8 0.3 ND ND

Negative ion F ^- Cl ^- NO ₂ ^- Br ^- NO ₃ ^- PO ₄ ^{3 -} SO ₄ ^{2 -} Before removal 81.1 29.5 81.2 15.8 822.1 378.2 423.5 After removal 1.3 3.4 6 ND 6.1 5.5 2.4

From the above table, it can be seen that after the smut removal, the cations of Na ⁺ were reduced together with the anion serving as the adhesion salt of the alloying component as compared with before the removal.

Claims (2)

A surface treatment method comprising a metal component constituting a vacuum treatment apparatus as a workpiece, wherein the surface of the workpiece is subjected to electropolishing, partial electrolytic treatment, chemical polishing, pickling, or electrolytic pickling, and at least 0.5% by weight and less than 3% by weight. The surface of the object to be treated with an alkaline chelating solution obtained by adding carboxylic acid or a carboxylic acid salt so as to have a concentration of at least 0.5% by weight and less than 10% by weight to the dilute alkaline liquid of. . The surface treatment method according to claim 1, wherein the temperature of the alkali chelate liquid is 10 to 80 ° C.

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