JP3089338B2 - Tin replacement liquid on aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin substitution liquid on an aluminum alloy and a tin substitution method.

[0002]

2. Description of the Related Art Since an aluminum alloy has a strong oxide film on its surface, it is not possible to directly form an electroplating film having good adhesion on this surface. For this reason, as a method of forming an electroplating film having good adhesion on an aluminum alloy, for example, a method of performing electroplating after substituting and depositing a tin film on the surface thereof is known. Examples of the tin replacement liquid used for such a purpose include, for example, Japanese Patent Publication No. Sho 61-30035, an aqueous solution containing an alkali metal stannate, methyl cellulose ethers, polyvinyl alcohols, polyethylene oxides, polyethylene glycols. A replacement liquid containing an additive such as described above is described.

[0003] On the other hand, a tin film is known to have excellent slidability, and by utilizing such film characteristics, a tin substitution film is formed on an aluminum alloy piston cylinder to thereby make the cylinder slide. Attempts have been made to improve mobility. However, in the case of the above-described tin-substitute solution for the base film of electroplating, the formed tin film is gray and has a poor appearance, and the film thickness is thin, so that sufficient slidability cannot be obtained.

[0004] As a tin replacement liquid for improving the sliding property of an aluminum alloy piston cylinder, for example, Japanese Patent Publication No. 50-3253 discloses an aqueous solution containing a stannate of an alkali metal. A replacement solution containing a chelating agent having a carboxylic acid anion is described. With the replacement liquid having such a composition, it is possible to form a film having good slidability, but as the treatment amount of the aluminum alloy increases, tin turbidity occurs in the bath, and sediment is formed. Tin that has been generated and settled once cannot be melted again, and is a factor that adheres to the surface of the aluminum alloy and hinders formation of a uniform tin film, and thus has the disadvantage of a short bath life.

In Japanese Patent Publication No. 2-153074,
Along with divalent tin salts such as stannous sulfate and stannous acetate,
An acid tin substitution liquid containing fluorine ions is described, but this substitution liquid is intended for a bimetal bearing composed of an aluminum alloy and an iron-based metal, and is formed for an aluminum alloy. The tin film becomes gray in appearance and has poor sliding properties. In addition, there is also a disadvantage that it contains fluorine ions, which is not preferable for environmental hygiene.

[0006]

SUMMARY OF THE INVENTION The main object of the present invention is to:
An object of the present invention is to provide a tin replacement liquid that can form a tin film having good sliding properties on an aluminum alloy, has a long bath life, and has almost no adverse effect on the environment.

[0007]

The present inventors have conducted intensive studies in view of the above-mentioned problems in the prior art, and as a result, have found that an aqueous solution containing an alkali metal stannate contains an amino acid and a divalent copper salt. With a tin-substituted liquid to which tin is added, a uniform tin film having excellent slidability can be formed, and even when the throughput of the aluminum alloy is increased, there is no sedimentation and the tin has a long bath life. The inventors have found that the solution becomes a replacement solution, and have now completed the present invention.

That is, the present invention provides an alkali metal stannate salt of 10 to 300 g / l, an amino acid of 1 to 100 g / l,
And 0.001 to 1.0 g of divalent copper salt as copper metal amount
/ L of an aqueous solution containing an aqueous solution containing tin / l, and a pH of 10 or more and a temperature of 3
An object of the present invention is to provide a method for replacing tin on an aluminum alloy, which comprises immersing the aluminum alloy in the replacement liquid at a temperature of 0 to 90 ° C.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, sodium stannate, potassium stannate and the like can be used as the alkali metal stannate, and these can be used alone or in combination of two or more. The compounding amount of the alkali metal stannate is about 10 to 300 g / l, preferably 50 to 300 g / l.
It is about 200 g / l. If the amount of the alkali metal stannate is too small, a sufficient tin film cannot be formed, while if the amount is too large, it becomes uneconomical, which is not preferable.

In the present invention, amino acids or salts thereof can be used as the amino acids, and these can be used alone or in combination of two or more. Specific examples of amino acids include alanine, glycylalanine, glycine, glycylglycine, glycylglycylglycine, glutamic acid, acetylmethionine, serine, valine,
Examples include titrulline, lysine, histidine, leucine, tryptophan, tyrosine, cysteine, arginine, aspartic acid, cysteine, cystine, proline, threonine and the like. Salts, sulfates, acetates, hydrochlorides and the like can be mentioned. Particularly preferred amino acids include alanine, glycylalanine, glycine, glycylglycine, glycylglycylglycine,
Glutamic acid, acetylmethionine, serine, valine,
Examples include amino acids such as titrulline and lysine, alkali metal salts such as potassium salts and sodium salts of these amino acids, sulfates and acetates. The compounding amount of amino acids is about 1 to 100 g / l, preferably 2 to 50 g / l.
g / l. If the amount of the amino acids is too small, sediments are liable to be formed in the bath when the treatment amount of the aluminum alloy is increased.On the other hand, when the amount of the amino acid is too large, the solubility is reduced due to approaching a saturated state, and It is not preferable because it is uneconomical.

In the present invention, as the divalent copper salt, for example, copper sulfate, copper acetate, copper tartrate, copper gluconate, copper pyrophosphate, copper nitrate, copper chloride, copper citrate and the like can be used. These can be used alone or in combination of two or more. Particularly preferred copper salts are copper sulfate, copper acetate,
Copper tartrate, copper gluconate, copper pyrophosphate and the like. The amount of the copper salt is 0.001 to 1.0 g / l as the amount of copper metal.
And preferably about 0.001 to 0.5 g / l. If the amount of the copper salt is too small, the appearance of the tin film formed becomes gray and the slidability becomes poor, while if the amount of the copper salt is large, the appearance of the tin film becomes black,
Again, the slidability is undesirably reduced.

The tin-substituted solution of the present invention is an aqueous solution containing the above-mentioned alkali metal stannate, amino acids and divalent copper salt as essential components. The pH of the tin replacement solution is 10
And more preferably about 11.5 or more. If the pH of the tin-substituted solution is too low, the tin in the bath is settled, which is a factor that hinders the coating of the tin film. The upper limit of the pH is not particularly limited.
Since a uniform and slidable tin film cannot be formed, it is appropriate to set the pH within a range that does not cause excessive etching of the material according to the type of the aluminum alloy used.

According to the tin replacement liquid of the present invention, a tin film can be formed on the surface of the aluminum alloy by immersing the aluminum alloy to be treated in the replacement liquid. At this time, the temperature of the tin replacement liquid is 30 to 90 ° C.
About 40 to 80 ° C., and more preferably about 40 to 80 ° C. If the treatment temperature is too low, the resulting tin film has a gray appearance and good slidability cannot be obtained.On the other hand, if the treatment temperature is too high, the aluminum alloy as a raw material is violently etched and becomes uniform. It is not preferable because a tin film having slidability cannot be formed.

The processing time is not particularly limited, but usually,
A uniform film can be formed in about 1 to 3 minutes.

The aluminum alloy to be treated in the present invention is not particularly limited, and various wrought materials, cast materials and the like can be used. Among such aluminum alloys, for example, wrought materials are JIS-based 2000 alloys, and cast materials are AC4A and AC4.
B, AC4C, AC4CH, AC4D, AC8A, AC
8B, AC8C, ADC1, ADC3, ADC10, A
A JIS-named aluminum alloy such as DC12 can be mentioned as a preferable example.

[0016]

According to the tin substitution liquid of the present invention, a white tin film having good slidability can be formed on an aluminum alloy. In addition, the replacement liquid is less likely to cause sediment even when the throughput of the aluminum alloy is increased, and has a much longer life than the conventional tin replacement liquid.

[0017]

The present invention will be described below in more detail with reference to examples and comparative examples. In the following Examples and Comparative Examples, an aluminum alloy represented by ADC12 JIS was used as a test piece.

Example 1 Sodium stannate 100 g / l, alanine 30 g / l,
Using an aqueous solution having a pH of 12.0 (adjusted with sodium hydroxide) containing copper sulfate and 0.2 g / l of copper sulfate (as the amount of copper metal) as a tin replacement solution, the test piece was immersed in the replacement solution at 50 ° C. for 2 minutes. . As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same treatment is continuously performed, and the replacement solution 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

EXAMPLE 2 A p-type containing 100 g / l potassium stannate, 30 g / l glycine and 0.2 g / l copper acetate (as copper metal)
Using an aqueous solution of H12.0 (adjusted with potassium hydroxide) as a tin replacement solution, the test piece was immersed in the replacement solution at 60 ° C. for 3 minutes. As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same treatment is continuously performed, and the replacement solution 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Example 3 pH 13.0 containing 150 g / l of sodium stannate, 30 g / l of sodium glutamate, 10 g / l of alanine and 0.2 g / l of copper tartrate (as copper metal content)
Using an aqueous solution (adjusted with sodium hydroxide) as a tin replacement solution, the test piece was immersed in the replacement solution at 60 ° C. for 3 minutes.
As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same treatment is continuously performed to obtain the replacement solution 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Example 4 150 g / l potassium stannate, 3 g glycidylglycine /
1, an aqueous solution of pH 12.5 (adjusted with potassium hydroxide) containing 10 g / l of lysine acetate and 0.2 g / l of copper gluconate (as the amount of copper metal) was used as a tin replacement solution, and replaced at 70 ° C. The test piece was immersed in the solution for 3 minutes. As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same treatment is continuously performed, and the replacement solution 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Example 5 Potassium stannate 70 g / l, acetylmethionine 5 g /
l and copper pyrophosphate (as the amount of copper metal) 0.2 g / l
Was used as a tin replacement solution, and the test piece was immersed in a replacement solution at 75 ° C. for 3 minutes. As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same treatment is continuously performed, and the replacement solution 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Example 6 pH 12.0 (adjusted with sodium hydroxide) containing 120 g / l of sodium stannate, 20 g / l of serine, 10 g / l of sodium glutamate and 0.4 g / l of copper sulfate (as the amount of copper metal) The test piece was immersed in the replacement solution at 60 ° C. for 3 minutes using the aqueous solution of (2) as a tin replacement solution. As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same treatment is continuously performed, and the replacement liquid 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Example 7: 120 g / l of potassium stannate, 10 g / l of titrulline,
An aqueous solution of pH 12.5 (adjusted with potassium hydroxide) containing 0.3 g / l of copper acetate (as the amount of copper metal) and copper acetate was used as a tin replacement solution, and the test piece was immersed in the replacement solution at 70 ° C. for 3 minutes. . As a result, a uniform white tin film is formed,
The coating had good slidability.

Further, the same treatment is continuously performed, and the replacement solution 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Example 8 120 g / l of sodium stannate, 20 g / l of valine, 10 g / l of alanine, and copper tartrate (as the amount of copper metal)
An aqueous solution containing 0.4 g / l and having a pH of 12.5 (adjusted with sodium hydroxide) was used as a tin replacement solution, and the test piece was immersed in the replacement solution at 60 ° C. for 3 minutes. As a result, a uniform white tin film was formed, and the film had good slidability.

Further, the same processing is continuously performed, and the replacement liquid 1
Even when the treated area of the test piece per liter was 30 dm ² / l, no sediment was generated in the bath, and a good tin film could be formed.

Comparative Example 1 An aqueous solution containing 60 g / l of potassium stannate and 3 g / l of disodium ethylenediaminetetraacetate and having a pH of 12.5 (adjusted with potassium hydroxide) was used. Soak for minutes. As a result, a tin film having a gray appearance was formed, and the film had poor slidability.

Further, the same treatment is continuously performed, and the replacement liquid 1
When the treated area of the test piece per liter was 30 dm ² / l, white sediment was generated in the bath,
The bath life was short.

COMPARATIVE EXAMPLE 2 Using an aqueous solution containing 60 g / l of sodium stannate and 15 g / l of sodium gluconate and having a pH of 12.5 (adjusted with sodium hydroxide), three test pieces were placed in a solution at 60 ° C.
Soak for minutes. As a result, a tin film having a gray appearance was formed, and the film had poor slidability.

Further, the same processing is continuously performed, and the replacement liquid 1
When the treated area of the test piece per liter became 30 dm ² / l, a brown sediment was generated in the bath,
A good tin film could not be formed, and the bath life was short.

Comparative Example 3 Stannous sulfate 20 g / l, ammonium acid fluoride 10
g / l, and pH 2.0 containing 30 g / l citric acid
Using an aqueous solution (adjusted with sulfuric acid), the test piece was immersed in a solution at 40 ° C. for 3 minutes. As a result, a tin film having a gray appearance was formed, and the film had poor slidability.

Further, the same treatment is continuously performed, and the replacement liquid 1
When the treated area of the test piece per liter was 30 dm ² / l, white sediment was generated in the bath,
The bath life was short.

Comparative Example 4 Stannous sulfate 30 g / l, acid ammonium fluoride 5 g
The test piece was immersed in a solution at 40 ° C. for 3 minutes using an aqueous solution containing 1.0 g / l, ethylenediaminetetraacetic acid 40 g / l, and tartaric acid 40 g / l at a pH of 1.0 (adjusted with sulfuric acid). As a result, a tin film having a gray appearance was formed, and the film had poor slidability.

Further, the same treatment is continuously performed, and the replacement solution 1
When the treated area of the test piece per liter was 30 dm ² / l, white sediment was generated in the bath,
The bath life was short.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 18/00-18/54

Claims (4)

(57) [Claims] 1. An alkali metal stannate salt of 10 to 300 g /
1, a tin replacement liquid on an aluminum alloy comprising an aqueous solution containing 1 to 100 g / l of amino acids and 0.001 to 1.0 g / l of a divalent copper salt as a copper metal amount. 2. The method according to claim 2, wherein the amino acids are alanine, glycylalanine, glycine, glycylglycine, glycylglycylglycine, glutamic acid, acetylmethionine, serine,
The tin substitution liquid according to claim 1, which is at least one selected from valine, titrulline, lysine, and alkali metal salts, sulfates, and acetates of these amino acids. 3. The copper salt of a divalent copper salt, copper sulfate, copper acetate, copper tartrate,
3. The tin replacement liquid according to claim 1, which is at least one selected from copper gluconate and copper pyrophosphate. 4. The method according to claim 1, wherein the tin-substitute solution is adjusted to a pH of 10 or more and the temperature of the solution is 30 to 90 ° C., and the aluminum alloy is immersed in the substitution solution. Method of tin substitution.