JPH02133596A - Aluminum electroplating bath ensuring superior sticking power and plating method with same bath - Google Patents

Abstract

PURPOSE:To improve sticking power in Al electroplating by adding a specified amt. of a specified org. solvent to a molten salt bath consisting of an aluminum halide and butylpyridinium chloride. CONSTITUTION:A molten salt bath consisting of 50-80mol% aluminum halide represented by a formula AlX3 (where X is F, Cl, I or Br) and 20-50mol% butylpyridinium chloride (C5H5N-C4H9Cl) is prepd. and one or more among diethylbenzene, cumene, mesitylene, dichlorobenzene and trichlorobenzene are added to the molten salt bath by 0.2-3mol per 1mol aluminum halide. Al plating is carried out in the org. solvent added plating bath with DC or pulsating current at 0-150 deg.C bath temp. and 0.02-50A/dm<2> average current density. Sticking power is improved by the plating bath.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an electrolytic aluminum plating made of an aluminum halide-butylvinonium chloride organic solvent with improved throwing power (uniform electrodeposition). ! This invention relates to a bath and a plating method using the bath.

(Prior art) The present inventors previously developed aluminum halide (^1x3, but L
X is F% CI, I, Br) 50-80 mol 9i dobutylpyridinium chloride (C6It, N-C, II,
proposed a plating bath in which an organic H agent was added to a molten salt bath consisting of 20 to 50 mol% CI) (Japanese Patent Laid-Open No. 62-7059).
No. 3).

(Problems to be Solved by the Invention) This plating bath used aromatic hydrocarbons such as benzene, toluene, and xylene as organic solvents.
When such a solvent is used, uniform plating cannot be achieved unless the average current density is 0.1A/dm2 or higher, and if the average current density is less than 0.1A/dm, the throwing power is poor. For this reason, when plating a material to be plated with unevenness at a low current density, there was a problem that the plating was difficult to adhere to the recessed portions away from the anode.

(Means for Solving the Problems) The present invention provides that the organic solvent added to the molten salt bath having the composition of aluminum halide and butylpyrinonium chloride in the above-mentioned ratio includes ()) ethylbenzene, cumene, mesitylene,
( ), tri) Using chlorobenzene, one of these or
This is 0 or more types per mole of aluminum halide.
．． By adding 2 to 3 moles, the throwing power was improved. This bath was designed to allow plating with direct current or pulsed current at a bath temperature of 0 to 150°C and an average current density of 0.02 to 50^/d+2.

The reason why the throwing power of the plating according to the present invention is improved is thought to be because the viscosity of the bath is lower than that of conventional baths to which benzene, toluene, quintin, etc. are added.

()) The reason why the amount of organic solvents such as ethylbenzene and cumene added is set to 0.2 to 3 mol per 1 mol of aluminum halobide is that if it is less than 0.2 mol, the coverage of the plating cannot be improved, and if it exceeds 3 mol. This is because even if it is added, the melting angle will not increase in the bath. The ethyl group position of noethylbenzene is ortho,
The chloro group position of chlorobenzene may be either meta or chlorobenzene.
It may be in the 4 position or in the 1,3.5 position.

During plating, the bath temperature should be between 0 and 150°C because if it is less than 0°C, the viscosity of the bath will be extremely high, the conductivity will be reduced and the throwing power will be poor, and if it exceeds 150°C, the bath will deteriorate significantly. This is because stable plating cannot be obtained because the process is fast.

In addition, the reason why the average current density is set to 0.02 to 50/dL62 is because if it is less than 0.02^/dm2, the maneuverability is poor, and if it is more than 50^/dm2, plating burnout will occur. . For current 1, either direct current or pulsed current may be used, but the latter is preferable when plating with high current density. The effect remains the same whether it is a steel plate or a nonferrous metal plate such as a metal plate, a nickel plate, or a copper plate.

(Example) Alkaline electrolytic degreasing, water washing,
After performing pretreatment in the order of pickling and water washing, it was dried in the air and used as a cathode, an aluminum plate (purity 99.99u+t).
%) was electroplated using a plating bath containing 70 mol % of aluminum chloride and 30 mol % of butylvinonium chloride to which the organic solvent of the present invention was added. Tables 1 to 5 show the results.

Table 1 Table 1 Table 2 Table 2 Table 2 Table 1 (Comparative example) Cold rolled steel sheets were electrolyzed with aluminum in the same manner as in the examples. The plating baths had the same mole percentage ratio of aluminum chloride and butylpyridinium chloride, and used a bath containing benzene as a solvent and a bath containing a mixed solvent of benzene-toluene. The results are shown in Table 6.

Table 6 (Effects of the Invention) As described above, the organic solvent added to the molten salt bath of aluminum halide and butylpyridinium chloride ())
Ethylbenzene, cumene, mesitylene, (), tri)chlorobenzene improves the throwing power.

Claims (3)

[Claims] (1) Aluminum halide (AlX_3, where X is F, Cl, I, Br) 50-80 mol% and butylpyridinium chloride (C_5H_5N-C_4H_9Cl)
0.2 to 3 mol of one or more of (di)ethylbenzene, cumene, mesitylene, and (di,tri)chlorobenzene is added per mol of aluminum halide to a molten salt bath consisting of 20 to 50 mol%. An electrolytic aluminum plating bath with excellent throwing power. (2) Using the plating bath according to claim 1, at a bath temperature of 0 to 150°C and an average current density of 0.02 to 50 A/
An electrolytic aluminum plating method with excellent coverage, characterized by plating with dm^2 direct current or pulsed current. (3) The electrolytic aluminum plating method with excellent throwing power according to claim 2, characterized in that plating is performed using an aluminum anode as the anode.