JP3033596B2 - Electric Al-Mg alloy plating bath and plating method using the bath - Google Patents

Description

The present invention relates to an electric Al-Mg alloy plating bath which can be plated at room temperature or relatively low temperature, and a plating method using the bath. (Prior art) Al-Mg alloy is: Light, strong, corrosion resistant,
Since it has excellent alumite properties, it has been conventionally used for applications requiring such properties, for example, for wall members of marine containers. However, this alloy contains expensive Mg and is extremely expensive, so that the price has been a great limitation for expanding the application.

(Problems to be solved by the invention) One way to solve this price problem is to use Al-Mg
It is conceivable that the alloy sheet is pressed against a structural material such as a steel sheet to form a clad material.However, since Al-Mg alloy has a large work hardening ability, annealing and rolling must be repeated to make the sheet thin. No. For this reason, the rolling cost increases, and the price problem has not been solved.

Another way to solve the price problem is to use Al-
Although a method of applying an Mg alloy plating is conceivable, when an Al-Mg alloy is plated by a hot-dip plating method, a Fe-Al alloy layer grows and the workability of the plated layer is extremely poor. To suppress the growth of the alloy layer, it is sufficient to add Si, but if Si is added, the corrosion resistance is reduced. On the other hand, according to the electroplating method, although the growth of the alloy layer can be suppressed, an electroplating method capable of plating an Al-Mg alloy at a bath temperature at which the alloy layer is not grown has not been developed yet.

In view of the above, the present invention provides an electric Al-Mg alloy plating bath capable of electroplating an Al-Mg alloy at a bath temperature at which an alloy layer is not grown, and a plating method using the bath.

(Means for Solving the Problems) The present inventors have developed the following plating bath as an electric Al-Mg alloy plating bath.

(1) An electric Al-Mg alloy plating bath containing the following components (A), (B) and (C).

(A) 33-67 mol% of aluminum halide (B) Magnesium halide and / or alkali metal salt of fluoromagnesic acid
(C) alkylpyridinium halide or alkylimidazolium halide (however, the alkyl group has 1 to 12 carbon atoms) 33 to 67 mol% (2) Plating bath of (1) above Al-Mg alloy plating bath with an aromatic organic solvent added.

(3) An electric Al-Mg alloy plating bath obtained by adding an aromatic compound having a nitrogen atom to the plating bath of (1).

As a method of electroplating using these plating baths, a plating method using a DC or pulse current at a bath temperature of 25 to 180 ° C. and a current density of 0.01 to 100 A / dm ² was developed.

Although the three electric components of the plating bath of the present invention are all solid, they melt when mixed and become a liquid molten salt bath even at room temperature, and have an Mg content of 0.1 to 70% by electroplating.
Alloy plating is possible.

In the plating bath of the present invention, aluminum halide
33-67 mol% is contained. When the content of this compound is less than 33 mol%, alkylpyridinium ions and alkylimidazolium ions increase, which adhere to the plating layer, and when it exceeds 67 mol%, the melting point of the plating bath increases, which is not preferable. . This aluminum halide
General formula AlX ₃ (X is a halogen atom such as F, Cl, Br, I, etc.)
It is shown by.

In the present invention, 0.01 to 67 mol% of a magnesium halide or an alkali metal salt of fluoromagnesic acid is contained together with the aluminum halide.
When the content of these magnesium compounds is less than 0.01 mol%, Mg ions become insufficient, and depending on the electrolysis conditions, Mg
May not be electrodeposited. On the other hand, if it exceeds 67 mol%, the melting point of the plating bath becomes high, which is not preferable.

The magnesium halide used here is:
General formula MgX ₂ (X is a halogen atom such as F, Cl, Br, I)
And the alkali metal salt of fluoromagnesic acid is M Mg F ₃ or M ₂ Mg F ₄ (M is an alkali metal).

In the present invention, an alkali pyridinium halide or an alkyl imidazolium halide is used together with the aluminum halide and the magnesium compound.
33-67 mol% is contained. These compounds have a content of
If it is less than 33 mol%, the melting point of the plating bath will increase,
If the amount exceeds mol%, the amount of alkylpyridinium ions and alkylimidazolium ions increases, which adheres to the plating layer, which is not preferable. If an alkyl group introduced into a pyridine ring or an imidazole ring has 13 or more carbon atoms, it is difficult to become a liquid at room temperature and the viscosity becomes high.

The alkylpyridinium halide is preferably a monoalkyl-substituted, dialkyl-substituted, or trialkyl-substituted, and may be one or a mixture of two or more of these. The halogen atom may be fluorine, chlorine, bromine or iodine. Specific examples of such a compound include butylpyridinium halide, 1,2-dimethylpyridinium halide, 1-ethyl-2-methylpyridinium halide, 1-n-butyl-2-methylpyridinium halide, 1 -Isobutyl-2-methylpyridinium halide, 1-n-octyl-2-
Methylpyridinium halide, 1-benzyl-2-
Methylpyridinium halide, 1-ethyl-3-methylpyridinium halide, 1-cyclohexyl-
3-methylpyridinium halide, 1-ethyl-2
-Ethylpyridinium halide, 1-butyl-2-
Ethylpyridinium halide, 1-ethyl-4-methylpyridinium halide, 1-ethyl-2,4-dimethylpyridinium halide, 1-ethyl-2,6-
Dimethylpyridinium halide, 1-n-butyl-
2,4-dimethylpyridinium halide and the like can be mentioned.

The alkyl imidazolium halide is 1-
Alkyl, 1,3-dialkyl and 1,2,3-trialkylimidazolium halides are preferred, and may be halogen atoms, fluorine, chlorine, bromine and iodine. These may be used alone or in combination of two or more. When these compounds are specifically shown, 1-methylimidazolium bromide, 1
-Ethylimidazolium halide, 1-butylimidazolium halide, 1,3-dimethylimidazolium halide, 1-methyl-3-ethylimidazolium halide, 1-methyl-3-n-butylimidazolium halide , 1-methyl-3-benzylimidazolium halide, 1-methyl-3-ethylbenzimidazolium halide, 1,2,3-trimethylimidazolium halide, 1,2-dimethyl-3-ethylimidazolium halogen And 1,2-dimethyl-3-butylimidazolium halide.

In the case of this alkylpyridinium halide, an amino group may be introduced. For example, 1-methyl-
4-dimethylaminopyridinium halide, 1-ethyl-4-dimethylaminopyridinium halide,
1-ethyl-4- (N-ethyl, N-methyl) aminopyridinium halide, 1-ethyl-4-aminopyridinium halide, 1-n-butyl-4-dimethylaminopyridinium halide, 1-benzyl-4 −
Examples include dimethylaminopyridinium halide, 1-n-octyl-4-dimethylaminopyridinium halide, 1-ethyl-4-piperidinopyridinium halide, 1-ethyl-4-pyrrolidinopyridinium halide, and the like.

The alkyl imidazolium halide may form a condensed ring. Representative examples of the fused heterocyclic compound are dialkylbenzimidazolium halides, and specific examples thereof include 1,3-dimethylbenzimidazolium chloride and 1-methyl-3-ethylbenzimidazolium bromide. Can be.

Among the compounds listed above, a preferred combination is Al
Cl ₃ -MgCl ₂ - butyl pyridinium chloride based or Al
Cl ₃ -MgCl ₂ -1-ethyl-3-methylimidazolium chloride is preferred, but the latter plating method is particularly preferred because of its high conductivity and low viscosity. In addition, baths in which part or all of MgCl ₂ is replaced with an alkali metal salt of fluoromagnesic acid in these plating baths are also preferred.

The plating bath of the present invention, an aromatic organic solvent is added,
When the viscosity of the plating solution is reduced, the conductivity is improved, the plating current density can be increased, and the plating layer can be smoothed. If the addition of the organic solvent is less than 5 Vol% with respect to the total amount of the plating bath, the addition effect is not recognized, and if it exceeds 80 Vol%, uniform mixing with the plating solution becomes difficult and separation occurs. It is preferable to make it 5 to 80% by volume.

Further, when an aromatic compound having a nitrogen atom is added to the plating bath of the present invention, it is possible to prevent the plating layer from becoming dendritic during thick plating. When this additive is added, even if the thickness is 30 μm or more, the surface is bright, and even if the current density is varied over a wide range, a smooth plating layer is obtained, and the uniform electrodeposition property is improved.

Examples of the aromatic compound include an unsaturated heterocyclic compound having two or more nitrogen atoms in a ring, an aromatic compound having an amino group, and the like.
It may be a fused ring compound. Examples of unsaturated heterocyclic compounds having two or more nitrogen atoms in the ring include diazines such as pyrimidine and barbituric acid, naphthyridine, phenazine, phenanthroline, pyridazine, and pyrazine.
Examples of the aromatic compound having an amino group include aminodiazines such as diphenylamine and aminopyrimidine, and two or more of them can be used in combination.

The addition amount of the aromatic compound having a nitrogen atom is usually 0.001 to 1 mol% with respect to the plating bath. 0.001 added
If it is less than mol%, there is no effect of addition, and if it is more than 1 mol%, plating burns when plating at a high current density.

Plating using the plating bath of the present invention is carried out in a dry oxygen-free atmosphere, at a bath temperature of 25 to 180 ° C. with direct current or pulse current,
When the current density is 0.01 to 100 A / dm ² , the current efficiency is good and the plating can be performed uniformly. When the bath temperature is lower than 25 ° C., the viscosity of the plating solution is high, and the current density becomes extremely small. When the bath temperature is higher than 180 ° C., there is a concern about decomposition of organic components. The plating can be performed sufficiently at room temperature to 60 ° C. without setting the bath temperature to 100 ° C. or higher. When a pulse current is used, the plating layer becomes dense. When aluminum or magnesium is used for the anode, according to the consumption of Al ions and Mg ions,
Advantageously, these ions are supplemented by dissolution of the anode. When the plating bath is subjected to ultrasonic stirring, jet jet stirring, or the like, the current density can be increased.

(Example) An electric Al-Mg alloy plating bath having the composition shown in Table 1 was prepared, and a cold rolled steel sheet having a thickness of 0.5 mm was formed using this plating bath.
-An Mg alloy was electroplated. Plating is performed by subjecting the cold-rolled steel sheet to solvent vapor washing, alkali degreasing and pickling in a conventional manner, followed by drying and immediately immersing the cold-rolled steel sheet in a plating bath kept in an inert gas atmosphere in advance. Aluminum plate or magnesium plate (both 99.99% pure, 1m thick)
m) was used as an anode, and electrolysis was performed with a direct current. Al obtained in Table 2
-Shows the performance of Mg alloy plated plate.

(Effect of the Invention) As described above, according to the plating bath of the present invention, an Al-Mg alloy can be plated by an electroplating method. Further, it is possible to easily electroplate Al-Mg alloys having different Mg contents only by adjusting the amount of magnesium halide or alkali metal fluoromagnesate which is the Mg ion source component of the plating bath. Furthermore, plating is possible even at a normal or relatively low bath temperature,
Easy to handle.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsuru Nishihata 1 at 7-Takatani-Shimmachi, Ichikawa-shi, Chiba Pref. 1 Nisshin Steel Corporation New Materials Research Laboratory (56) References JP-A-64-79394 (JP, A) JP-A-1-272790 (JP, A) JP-A-61-261494 (JP, A) JP-A-61-295394 (JP, A) JP-A-49-133225 (JP, A)

Claims (6)

(57) [Claims] An electric Al-Mg alloy plating bath containing the following components (A), (B) and (C). (A) 33-67 mol% of aluminum halide (B) Magnesium halide or alkali metal salt of fluoromagnesic acid or both of them 0.01
(C) alkylpyridinium halide or alkylimidazolium halide (however, the alkyl group of each compound has 1 to 12 carbon atoms) 33 to 67 mol% 2. The electric Al according to claim 1, wherein the alkylpyridinium halide is one or a mixture of two or more of monoalkyl, dialkyl and trialkylpyridinium halides. −
Mg alloy plating bath. 3. The method according to claim 1, wherein the alkyl imidazolium halide is 1
2. The electric Al-Mg alloy plating bath according to claim 1, wherein the bath is one or a mixture of two or more of -alkyl, 1,3-dialkyl, and trialkylimidazolium halides. . 4. An electric Al-Mg alloy plating bath, wherein an aromatic organic solvent is added to the plating bath of claim 1. 5. An electric Al-Mg alloy plating bath, wherein an aromatic compound having a nitrogen atom is added to the plating bath according to claim 1. 6. An electric Al-plating method using the plating bath according to any one of claims 1 to 5, wherein the plating is carried out at a bath temperature of 25 to 180 ° C. and a current density of 0.01 to 100 A / dm ² by direct current or pulse current. Mg
Alloy plating method.