JPH09143800A - High brightness electropolishing solution for stainless steel and electropolishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive electropolishing soln. capable of remarkably improving the surface brightness of a stainless steel by adding gluten or a wheat flour being a material containing the gluten to a sulfuric acid soln. and a (sulfuric acid + phosphoric acid) soln. SOLUTION: The electropolishing soln. is obtained by incorporating >=3g and <=60g gluten or >=8g and <=160g wheat flour into 1L soln. having >=40% and <=75% sulfuric acid concn. or >=40% and <=85% (sulfuric acid + phosphoric acid) concn. and the balance substantially water or by adding potassium dichromate or sodium dichromate or these mixture or ethanol to these soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electropolishing solution that greatly improves the electropolishing surface gloss of stainless steel by adding gluten (flour) to a sulfuric acid solution, a (sulfuric acid + phosphoric acid) solution, and electrolysis using the solution. The present invention 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, starch, etc., and these special additives accelerate the oxidative dissolution of the anode, enhance the polishing efficiency, and act as an inhibitor locally. It is described that the surface gloss is improved by suppressing various etching (Stainless Steel Handbook, January 24, 1995, published by Nikkan Kogyo Shimbun, p. 1143, M).
ETAL FINISHING, May 1991 issue,
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.

Therefore, the present inventors diligently studied a low-cost electropolishing solution that improves the surface gloss of stainless steel even at a relatively low temperature, and aimed to develop an electropolishing method suitable for industrial large-scale electropolishing.

[0005]

The gist of the present invention is as follows. (1) Stainless steel containing gluten in an amount of 3 g or more and 60 g or less or a flour containing 8 g or more and 160 g or less of flour as a substance containing gluten per liter of a solution having a sulfuric acid concentration of 40% or more and 75% or less and the balance being basically water Bright electrolytic polishing solution. (2) When the concentration of (sulfuric acid + phosphoric acid) is 40% or more and 85% or less,
A high-gloss electropolishing solution of stainless steel containing 3 g or more and 60 g or less of gluten or 8 g or more and 160 g or less of flour as a substance containing gluten per liter of a solution whose balance is basically water. (3) Replace with the gluten of (1) or (2) above,
A high-gloss electropolishing solution of stainless steel containing 8 g or more and 160 g or less of wheat flour per 1 liter of a solution containing gluten. (4) With the solution of any one of (1) to (3), 5 g or more of potassium dichromate or sodium dichromate or a mixture of potassium dichromate and sodium dichromate per liter of the solution, A high-gloss electrolytic polishing solution for stainless steel, containing 100 g or less. (5) The electrolysis of stainless steel according to any one of the above (1) to (4), wherein ethanol is contained in 1 liter of the solution in an amount of 1/3 or less of the weight of gluten added or the weight of wheat flour added. Polishing solution. (6) The anode is a stainless steel plate to be polished, and the above (1) to
A polishing liquid having a composition of 50 to 9 is added with any one of the solutions of (5).
Maintaining a constant temperature in the range of 0 ℃, electric capacity 1000C / dm ²
An electrolytic polishing method characterized by performing electrolytic polishing as described above.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention are earnestly studying a low-cost special additive for improving the electropolishing surface gloss of stainless steel. Extended range, extended solution life,
It has been found to be excellent in all aspects of low cost.
Wheat flour includes starch, which is a carbohydrate, and gluten, which is a protein (proteins such as glutenin and gluazine, published by RIKEN, July 18, 1994, published by Iwanami Shoten, p. 3).
59) is contained. Therefore, it was investigated whether the effect of adding starch or gluten would improve the electropolishing property by adding each of them individually. As a result, no improvement in electropolishability was confirmed by the addition of carbohydrates such as starch or sugar. On the other hand, it was confirmed that adding 3 g or more of gluten per liter of the solution significantly improved the electrolytic polishing property.

In this case, although the purified gluten has a high cost, it has the greatest feature of the present invention that it has been found that its effect can be sufficiently exerted by the addition of inexpensive edible wheat flour containing gluten. . Hereinafter, the sulfuric acid concentration is specified to be 40% or more and 75% or less, and gluten and wheat flour are 3 g / 1 and 8 g / 1 or more, 60%, respectively.
g and 160 g or less, (sulfuric acid + phosphoric acid) concentration is 40% or more and 85% or less, and gluten and wheat flour are 3 g / 1 and 8 g / 1 or more, 60 g / 1, respectively.
And the reason why it is defined as 160 g / 1 or less will be described.

1 and 2 show the results of measuring the relationship between the sulfuric acid concentration, the amount of gluten added per liter of the solution and the amount of wheat 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 gluten added per liter of the solution and the amount of wheat flour, and the electropolishing surface glossiness are shown. As is clear from FIG. 1 and FIG. 2, the sulfuric acid concentration of 40% or more was observed in the solution containing sulfuric acid alone.
Add less than 5% gluten and flour each 3
In the case of g / 1 and 8 g / 1 or more, good electropolishing surface gloss is obtained. When 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 addition amount to 1 and 160 g / 1 is that the viscosity of the solution increases too much and a high gloss cannot be obtained when the amount added is more than that,
Moreover, the circulation of the electrolytic polishing solution is hindered. Further, as is clear from FIGS. 3 and 4, the (sulfuric acid + phosphoric acid) solution has a (sulfuric acid + phosphoric acid) solution concentration of 40% or more, 8%.
Add less than 5% gluten and flour each 3
When it is at least g / 1 and at least 8 g / 1, good electropolishing surface gloss is obtained. As with sulfuric acid alone solution, the addition amount of gluten and flour is 60% / 1 and 160g, respectively
If it is / 1 or more, the viscosity of the solution increases too much, which is not preferable, so the upper limit of each addition amount was made. If the concentration of the (sulfuric acid + phosphoric acid) solution is less than 40% or more than 85%, high surface gloss cannot be obtained.

Further, the present applicant has previously filed Japanese Patent Application No. 7-1416.
No. 73 for low-cost electropolishing of stainless steel, 10 g of potassium dichromate was added to 1 liter of a solution having a sulfuric acid concentration of 45% or more and 60% or less and the balance being basically water.
As described above, a patent application has been filed for a high-gloss electropolishing solution for stainless steel, which contains 100 g or less.
~ Solution boiling temperature. By adding gluten or wheat flour to this solution, it becomes possible to obtain a high gloss electropolishing temperature range even at low temperatures, and 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 electropolishing conditions, an electric capacity of 1000 C / dm ² or more and a temperature of 50 to 90 ° C. provide high gloss. The reason why high gloss is obtained in such a low temperature region is not clear, but it is considered to be because the appropriate viscosity and film necessary for electrolytic polishing of the stainless steel surface are formed.

The reason for adding ethanol to the solution is to promote the disappearance of bubbles by hydrogen gas generated from the cathode and oxygen gas generated from the anode during the electropolishing. The amount of ethanol added was defined to be ⅓ or less of the weight of wheat flour added, because the viscosity of the wheat flour that exhibits the gloss polishing property of the solution is not reduced more than necessary.

[0013]

【Example】

(Example 1) Table 1 shows that gluten or wheat flour at 850 ° C. according to the present invention is used alone at 5 g / 1 or 10 g /
1 in the added sulfuric acid solution, SUS3 with a plate thickness of 0.3 mm
Current density 150A / dm for 04 steel plate and SUS430 steel plate (both cold-rolled and annealed plates with glossiness of 80 to 120)
Surface gloss after electropolishing at ² for 30 seconds (JISZ
The incident angle of 45 ° specular gloss specified in 8741) is shown in comparison with simple sulfuric acid solution, chromic acid, agar powder, potato starch and sugar added individually at 10 g / 1, but gluten or wheat flour was added. It is clear that when it is done, it exhibits a remarkably excellent surface gloss.

[0014]

[Table 1]

(Example 2) Table 2 shows the temperature of 85 ° C. according to the present invention.
When 5 g / 1 or 10 g / 1 of gluten or wheat flour of (3) was added (sulfuric acid + phosphoric acid) solution, electrolytically polishing a SUS304 steel plate and a SUS430 steel plate with a plate thickness of 0.3 mm at a current density of 150 A / dm ² for 30 seconds The surface gloss is shown in comparison with that of simple sulfuric acid solution, chromic acid, agar powder, potato starch, and sugar added individually at 10 g / 1, but when gluten or wheat flour is added, the surface gloss is significantly superior. It is clear that

[0016]

[Table 2]

(Embodiment 3) Table 3 shows the values of 50 to 50 according to the present invention.
90g gluten or wheat flour each 5g /
The electrolytic surface glossiness in a sulfuric acid solution containing 50 g / 1 of potassium dichromate added with 1 or 10 g / 1 was 9
It is shown in comparison with the case of electrolytic polishing at each temperature of 5 ° C. or higher.
It is clear that an electrolytic polishing temperature of 90 ° C. or lower is suitable when gluten or wheat flour is added.

[0018]

[Table 3]

(Embodiment 4) Table 4 shows the values of 50 to 50 according to the present invention.
90g gluten or wheat flour each 5g /
The electrolytic surface glossiness in a (35% sulfuric acid + 30% phosphoric acid) solution containing 50 g / 1 of potassium dichromate added with 1 or 10 g / 1 is shown in comparison with the case of electrolytic polishing at each temperature of 95 ° C. or higher. It is clear that an electrolytic polishing temperature of 90 ° C. or lower is suitable when gluten or wheat flour is added.

[0020]

[Table 4]

[0021]

The electropolishing solution of the present invention is cheaper than any of the conventionally used electropolishing solutions, and is excellent in the polishing temperature range and 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 sulfuric acid concentration and the amount of gluten added, which gives good electropolished surface gloss.

FIG. 2 is a diagram showing the relationship between the concentration of sulfuric acid and the amount of wheat flour that give good electropolishing surface gloss.

FIG. 3 is a graph showing the relationship between the concentration of (sulfuric acid + phosphoric acid) that gives good electropolishing surface gloss and the amount of gluten added.

FIG. 4 is a diagram showing the relationship between the concentration of (sulfuric acid + phosphoric acid) that gives good electropolishing surface gloss and the amount of wheat flour added.

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

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

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

FIG. 8 is a diagram showing the results of measuring the solution temperature and the amount of flour in a solution containing 20 g / 1 of potassium dichromate (30% sulfuric acid + 20% phosphoric acid) to obtain a high gloss surface.

(72) Inventor Masamitsu Tsuchinaga 1-1, Tobata-cho, Tobata-ku, Kitakyushu, Fukuoka Prefecture (72) Inside the Yawata Works, Nippon Steel Corporation (72) Takeharu Kataoka, Tobata-cho, Tobata-ku, Kitakyushu, Fukuoka 1-1 Nippon Steel Corporation Yawata Works

Claims (6)

[Claims] 1. A high-gloss electropolishing solution for stainless steel, which contains 3 g or more and 60 g or less of gluten per liter of a solution having a sulfuric acid concentration of 40% or more and 75% or less and the balance being basically water. . 2. The (sulfuric acid + phosphoric acid) concentration is 40% or more and 85%.
A high-gloss electropolishing solution for stainless steel, characterized in that gluten is contained in an amount of 3 g or more and 60 g or less per 1 liter of a solution whose balance is basically water. 3. In place of gluten, as a substance containing gluten, flour 8 g or more 16 per 1 liter of solution
The high-gloss electropolishing solution for stainless steel according to claim 1 or 2, which contains 0 g or less. 4. 5 g or more of potassium dichromate or sodium dichromate or a mixture of potassium dichromate and sodium dichromate with respect to 1 liter of the solution.
The high-gloss electrolytic polishing solution for stainless steel according to any one of claims 1 to 3, wherein the high-gloss electrolytic polishing solution contains 100 g or less. 5. The stainless steel according to claim 1, wherein ethanol is contained in an amount equal to or less than the amount of gluten added or 1/3 g of the amount of wheat flour added to 1 liter of the solution. Electropolishing solution for steel. 6. A stainless steel plate to be polished or a stainless steel strip is used as the anode, the polishing liquid having the composition according to any one of claims 1 to 5 is kept at a constant temperature in the range of 50 to 90 ° C., and the electric capacity is 1000 C / An electropolishing method for stainless steel, which comprises electropolishing with dm ² or more.