JP3117628B2 - High gloss electrolytic polishing solution for stainless steel and electrolytic polishing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electropolishing solution which significantly improves the electropolished surface gloss of stainless steel by adding gluten (wheat flour) to a sulfuric acid solution or a (sulfuric acid + phosphoric acid) solution, and an electropolishing solution using the solution. It relates to a polishing method.

[0002]

2. Description of the Related Art Electropolishing of stainless steel has been widely used since the 1930s. To improve the surface gloss of electropolishing, chromic acid, dichromate, oxalic acid, agar powder and phosphoric acid or (phosphoric acid + sulfuric acid) solution are used. , Glycerin, citric acid,
It is known to add gelatin, glue, glycolic acid, polyethylene glycol or starch, and these special additives promote the oxidative dissolution of the anode, increase the polishing efficiency, and act as an inhibitor locally. It is described that the surface gloss can be improved by suppressing excessive etching (Stainless Steel Handbook, January 24, 1995, published by Nikkan Kogyo Shimbun, p. 1143, M.
ETAL FINISHING, May 1991,
p. 47, PLATING AND SURFACE
FINISHING, June 1981, p. 4
4).

[0003]

The conventional electropolishing solution uses expensive phosphoric acid, and the organic compound as a special additive is decomposed to have an insufficient effective life. In addition, since a large amount of addition is required, there has been a problem that the cost of electrolytic polishing is significantly increased.
Further, since the electropolishing temperature is as high as 90 ° C. or higher, the electropolishing apparatus has to be manufactured from a highly corrosion-resistant material such as Teflon, and a remarkable increase in the cost of the electropolishing apparatus cannot be avoided.

Accordingly, the present inventors have intensively studied a low-cost electropolishing solution for improving the surface gloss of stainless steel even at a relatively low temperature, and aimed at developing an electropolishing method suitable for industrial mass electropolishing.

[0005]

The gist of the present invention is as follows. (1) Stainless steel containing 3 g to 60 g of gluten or 8 g to 160 g of wheat flour as a gluten-containing substance per liter of a solution having a sulfuric acid concentration of 40% to 75% and a balance of basically water. Gloss electrolytic polishing solution. (2) When (sulfuric acid + phosphoric acid) concentration is 40% or more and 85% or less,
A high-gloss electrolytic polishing solution of stainless steel containing 3 g to 60 g of gluten or 8 g to 160 g of flour as a substance containing gluten per liter of a solution in which the balance is basically water. (3) Instead of the above (1) or (2) gluten,
A high gloss electrolytic polishing solution of stainless steel containing 8 g or more and 160 g or less of flour per liter of a solution containing gluten. (4) 5 g or more of potassium dichromate or sodium dichromate, or a mixture of potassium dichromate and sodium dichromate, per liter of the solution in any one of the above (1) to (3); A high-gloss electrolytic polishing solution for stainless steel, containing 100 g or less. (5) Electrolysis of stainless steel characterized in that, in any one of the above solutions (1) to (4), 1 liter of the solution contains not more than 1/3 of the weight of gluten or flour added to ethanol. Polishing solution. (6) The anode is a stainless steel polished plate, and the above (1) to
Polishing liquid having a composition of 50 to 9 with any one solution of (5)
Maintain a constant temperature in the 0 ° C range, and have an electric capacity of 1000 C / dm ²
An electrolytic polishing method characterized by performing the electrolytic polishing described above.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention are studying low cost special additives for improving the surface polishing of stainless steel by electropolishing. Extended range, extended solution life,
We found it to be excellent in all respects at low cost.
Wheat flour includes starch, which is a carbohydrate, and gluten, which is a protein (proteins such as glutenin and gluadin, a dictionary of physics and chemistry, published on July 18, 1994, Iwanami Shoten, p.3).
59) is contained. Then, it was examined whether the effect of improving the electropolishing property is brought about by the addition effect of starch or gluten, by adding each alone. As a result, no improvement in electropolishing was confirmed by the addition of carbohydrates such as starch or sugar. On the other hand, a remarkable effect of improving the electropolishing property was confirmed by adding only 3 g or more of gluten per liter of the solution.

In this case, the purified gluten is expensive, but the most significant feature of the present invention is that it has been found that the effect can be sufficiently exerted by adding inexpensive edible flour containing gluten. . Hereinafter, the sulfuric acid concentration is specified to be 40% or more and 75% or less, and gluten and flour are respectively 3 g / 1 and 8 g / 1 or more, and 60% or less.
g and 160 g or less, the (sulfuric acid + phosphoric acid) concentration is regulated to 40% or more and 85% or less, and gluten and flour are respectively 3 g / 1 and 8 g / 1 or more and 60 g / 1.
And the reason for defining it as 160 g / 1 or less.

FIGS. 1 and 2 show the measurement results of the relationship between the sulfuric acid concentration, the amount of added gluten per liter of solution and the amount of flour, and the electropolishing surface glossiness, and FIGS. 3 and 4 show (sulfuric acid + phosphoric acid). The results of measuring the relationship between the concentration, the amount of added gluten per liter of the solution, the amount of flour, and the electrolytic polishing surface gloss are shown. As is clear from FIGS. 1 and 2, the sulfuric acid alone solution has a sulfuric acid concentration of 40% or more and 7%.
5% or less, gluten and flour should be added in 3
In the case of g / 1 and 8 g / 1 or more, good electrolytic polishing surface gloss can be obtained. If the sulfuric acid concentration is less than 40% or more than 75%, high surface gloss cannot be obtained.

On the other hand, the upper limit of each addition amount is 60 g /
The reason for limiting the amount to 1 and 160 g / 1 is that if the addition amount is more than that, the viscosity of the solution becomes too high to obtain high gloss,
Also, the circulation of the electropolishing solution is hindered. Further, as is apparent from FIGS. 3 and 4, the (sulfuric acid + phosphoric acid) solution has a (sulfuric acid + phosphoric acid) solution concentration of 40% or more and 8%.
5% or less, gluten and flour should be added in 3
In the case of g / 1 or more and 8 g / 1 or more, good electrolytic polishing surface gloss can be obtained. As with the sulfuric acid alone solution, the amounts of gluten and flour added are 60% / 1 and 160 g, respectively.
When the ratio is more than / 1, the viscosity of the solution is too high, which is not preferable. If the (sulfuric acid + phosphoric acid) solution concentration is less than 40% or more than 85%, high surface gloss cannot be obtained.

The present applicant has previously filed Japanese Patent Application No. 7-1416.
In No. 73, as a low-cost electrolytic polishing of stainless steel, 10 g of potassium dichromate was added to 1 liter of a solution in which the sulfuric acid concentration was 45% or more and 60% or less and the balance was basically water.
As described above, a patent application was filed for a high-gloss electrolytic polishing solution of stainless steel characterized by containing 100 g or less, and a preferable range of the electrolytic polishing temperature according to the present application is 90 ° C.
~ Solution boiling temperature. High gloss can be obtained by adding gluten or flour to this solution.Electropolishing temperature range is possible even at low temperatures. Addition of potassium dichromate or sodium dichromate, or a mixture of potassium dichromate and sodium dichromate The range is expanded to 5 g or more and 100 g or less.

As for the electropolishing conditions, a high gloss can be obtained at an electric capacity of 1000 C / dm ² or more and a temperature of 50 to 90 ° C. The reason why the high gloss is obtained in such a low temperature region is not clear, but it is considered to be because an appropriate viscosity and a film required for electrolytic polishing of the stainless steel surface are formed.

The reason for adding ethanol to the solution is to promote the elimination of bubbles due to hydrogen gas generated from the cathode and oxygen gas generated from the anode during electropolishing. The reason why the amount of ethanol added is specified to be not more than 1/3 of the weight of wheat flour added is to prevent the viscosity of the flour exhibiting the gloss polishing property of the solution from being reduced more than necessary.

[0013]

【Example】

(Example 1) Table 1 shows that gluten or flour at 850 ° C according to the present invention was alone at 5 g / 1 or 10 g / g respectively.
1 In the sulfuric acid solution added, SUS3
04 steel sheet and SUS430 steel sheet (both are cold rolled annealed sheets, gloss is 80 or more and 120 or less) with current density of 150 A / dm
Surface gloss when electropolished at ² for 30 seconds (JISZ
The incident angle 45 ° specular gloss specified in 8741) is shown in comparison with the case where simple sulfuric acid solution, chromic acid, agar powder, potato starch and sugar were individually added at 10 g / 1, but gluten or wheat flour was added. In this case, it is clear that the surface gloss is remarkably excellent.

[0014]

[Table 1]

Example 2 Table 2 shows that 85 ° C. according to the present invention was used.
Of SUS304 steel plate and SUS430 steel plate having a thickness of 0.3 mm in a solution obtained by adding 5 g / 1 or 10 g / 1 of gluten or flour alone at a current density of 150 A / dm ² for 30 seconds. The surface glossiness is shown in comparison with the case where simple sulfuric acid solution, chromic acid, agar powder, potato starch and sugar were each added alone at 10 g / 1, but the surface gloss was excellent when gluten or wheat flour was added. It is clear that

[0016]

[Table 2]

(Example 3) Table 3 shows that 50 to 50
Gluten or wheat flour at 90 ° C. alone 5 g /
Electrolytic surface glossiness in a sulfuric acid solution containing 50 g / 1 potassium dichromate added at 1 or 10 g / 1 was 9
The results are shown in comparison with the case where electropolishing is performed at each temperature of 5 ° C. or more.
When gluten or flour is added, it is clear that an electropolishing temperature of 90 ° C. or less is appropriate.

[0018]

[Table 3]

(Example 4) Table 4 shows that 50 to 50
Gluten or wheat flour at 90 ° C. alone 5 g /
The electrolytic surface gloss in a solution containing 35 g of sulfuric acid + 30% phosphoric acid containing 50 g / 1 of potassium dichromate added at 1 or 10 g / 1 is shown in comparison with the case of electrolytic polishing at each temperature of 95 ° C. or more. When gluten or flour is added, it is clear that an electropolishing temperature of 90 ° C. or less is appropriate.

[0020]

[Table 4]

[0021]

The electropolishing solution of the present invention is less expensive than any of the conventionally used electropolishing solutions, and is excellent in the polishing temperature range and the solution life. It is an innovative electropolishing solution for industrially producing stainless steel electropolishing products in large quantities.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the concentration of sulfuric acid and the amount of gluten added to obtain good electrolytic polishing surface gloss.

FIG. 2 is a graph showing a relationship between a sulfuric acid concentration and a flour addition amount at which good electrolytic polishing surface gloss is obtained.

FIG. 3 is a graph showing the relationship between (sulfuric acid + phosphoric acid) concentration at which good electrolytic polishing surface gloss is obtained and the amount of gluten added.

FIG. 4 is a graph showing the relationship between (sulfuric acid + phosphoric acid) concentration at which good electrolytic polishing surface gloss is obtained and the amount of flour added.

FIG. 5 containing 50 g / 1 of potassium dichromate
It is a figure which shows the result of having measured the solution temperature and gluten amount which can obtain a high gloss surface in 5% sulfuric acid solution.

FIG. 6 containing 50 g / 1 potassium dichromate
It is a figure which shows the result of having measured the solution temperature and wheat flour amount which can obtain a high gloss surface in a 5% sulfuric acid solution.

FIG. 7 is a graph showing the results of measuring the solution temperature and the amount of gluten at which a high glossy surface is obtained in a solution containing 20 g / 1 of potassium dichromate (30% sulfuric acid + 20% phosphoric acid).

FIG. 8 is a view showing the results of measuring the solution temperature and the amount of flour at which a high glossy surface is obtained in a solution containing 20 g / 1 of potassium dichromate (30% sulfuric acid + 20% phosphoric acid).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Masamitsu Tsukunaga 1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Yawata Works (72) Inventor Takeharu Kataoka Tobata-ku, Kitakyushu-shi, Fukuoka 1-1 Namihata-cho New Nippon Steel Corporation Yawata Works (58) Fields surveyed (Int. Cl. ⁷ , DB name) C25F 3/24

Claims (6)

(57) [Claims] 1. A high-gloss electrolytic polishing solution for stainless steel, characterized by containing 3 g to 60 g of gluten per liter of a solution having a sulfuric acid concentration of 40% or more and 75% or less and the balance being essentially water. . 2. The (sulfuric acid + phosphoric acid) concentration is 40% or more and 85% or more.
A high-gloss electrolytic polishing solution for stainless steel, characterized by containing 3 g or more and 60 g or less of gluten per liter of a solution whose balance is basically water. 3. Instead of gluten, 8 g or more of flour per liter of solution as a substance containing gluten is used.
The high-gloss electrolytic polishing solution for stainless steel according to claim 1 or 2, which contains 0 g or less. 4. More than 5 g of potassium dichromate or sodium dichromate, or a mixture of potassium dichromate and sodium dichromate, per liter of solution.
The high-gloss electrolytic polishing solution for stainless steel according to any one of claims 1 to 3, wherein the solution contains not more than 00 g. 5. The stainless steel according to claim 1, wherein 1 liter of the solution contains not more than the same amount of ethanol as gluten added weight or not more than 1/3 g of wheat flour added weight. Electropolishing solution for steel. 6. The anode is a stainless steel polished plate or a stainless steel strip, and the polishing liquid having the composition according to any one of claims 1 to 5 is maintained at a constant temperature in the range of 50 to 90 ° C. and has an electric capacity of 1000 C / cm. A method for electropolishing stainless steel, comprising electropolishing at dm ² or more.