JPH01149988A - Beryllium electroplating bath and plating method with said bath - Google Patents

Abstract

PURPOSE:To enable Be plating giving a smooth surface at a relatively low temp. by carrying out electroplating with a plating bath contg. a beryllium halide and an alkylpyridinium halide in a dry oxygen-free atmosphere under specified conditions. CONSTITUTION:A molten salt bath consisting of 30-90mol.% beryllium halide (BeX2) such as BeCl2 and 10-70mol.% alkylpyridinium halide (C5H5N-RX, wherein R is 1-5C alkyl) such as butylpyridinium chloride or a Be electroplating bath consisting of the halides and 20-80vol.% org. solvent is prepd. The surface of a copper plate or the like is electroplated with the plating bath at 0-200 deg.C in a dry oxygen-free atmosphere by supplying DC or pulsating current at 0.1-10A/dm<2> current density. Uniform smooth Be plating can be carried out at the relatively low temp. and high current density.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a molten base electroplating bath capable of uniformly and densely plating a pan at a relatively low temperature, and a plating method based thereon.

(Prior art) Be is stable and the lightest metal, so if Be plating is used in place of Cd plating, which is conventionally used for plating aircraft parts, the aircraft body can be made lighter. Because it has excellent high-temperature corrosion resistance against gas and molten metal, BeM's outer material is suitable for nuclear reactor parts, etc.BeM also has excellent sound transmission properties, so it is suitable for use in speaker diaphragms, etc. , excellent acoustic effects can be obtained.

The Be plating material and electrolytic foil must be manufactured by electroplating, but since the potential of Be is significantly less base than that of hydrogen, it is difficult to carry out the process using an aqueous plating bath. For this reason, Be electroplating has conventionally been carried out in non-aqueous plating baths such as organic solvent-based or molten salt-based plating baths.

For example, as organic solvents, dimethyl beryllium-diethyl ether baths, beryllium borohydride diethyl ether baths, beryllium dichloroacetate-methanol or 7cetone baths are used.
As molten salt baths, BeCl 2-NaCI baths and BeCIz LiCl KCl baths are used.

(Problems to be Solved by the Invention) However, since the organic solvent-based plating baths described above have low conductivity, the plating speed is slow, and it is also difficult to perform dense plating.

On the other hand, the molten salt bath has a plating temperature as high as several hundred degrees, resulting in poor workability and, moreover, the surface of the plating layer becomes dendritic during solidification.

Therefore, the present invention provides an electrolytic beryllium plating bath and a plating method that solve these problems.

(Means for Solving the Problems) As a result of intensive research in order to develop an electroplating bath free from the above-mentioned problems, the present inventor found that according to a molten salt bath of beryllium halide and alkylpyridinium halide, They discovered that plating can be performed at relatively low temperatures and the surface of the plating layer can be made smooth.

That is, the present inventor has discovered that beryllium halide (Be
X2) 30 to 90 mol% and alkylpyridinium halide (CsH6N-RX, where R is an alkyl group having 1 to 5 carbon atoms, X is a halogen atom) 10 to 70 mol%, or 20 to 80 vol% of an organic solvent to these We have developed an electrolytic beryllium plating bath consisting of a combination of the following: using this bath, electrolytic conditions are applied at a bath temperature of 0 to 200°C and a current density of 0.1 to 10^/dm2 using direct current or pulsed current in a dry oxygen-free atmosphere. It has been found that smooth plating is possible when plated.

Both beryllium halides and alkylpyridinium halides are solid at room temperature, but when mixed in the above ratio, they melt at around 50°C and become liquid, and they ionically dissociate into beryllium halide anions and alkylpyridinium cations, and undergo electrolysis. If finished, beryllium plated.

For example, a molten salt bath of beryllium chloride and butylpyrinonium chloride produces BeCI 3- and C5HJ"-C4H
It dissociates as in i, BeCl 3- receives electrons at the cathode, and Be is precipitated.

As the alkylpyridinium halide, it is preferable to use an alkyl group having 1 to 5 carbon atoms. This is because when the alkyl group has 6 or more carbon atoms, it becomes difficult to become liquid at low temperatures when mixed with beryllium halide.

The mixing ratio of beryllium halide is 30 to 90 mol%.
The reason for this is that if the beryllium halide content is less than 30 mol%, the concentration of alkylpyridinium cations in the bath will increase, and during Be electrodeposition, the alkylpyridinium cation reduction reaction will proceed simultaneously, resulting in a decrease in current efficiency and This is because it leads to poor surface appearance of the plating layer. Moreover, if it exceeds 90 mol%, the melting point will be high and the general conductivity will be low.
The vapor pressure also increases.

The mixing ratio of the alkylpyridinium halide is 10 to 70 mol % since it is the remainder of the beryllium halide.

Since this plating bath is a molten salt bath, when the bath temperature becomes low, the fluidity of the bath decreases, and it may be difficult to increase the current density. Therefore, in such a case, an organic solvent may be added to improve the fluidity of the bath. Even if an organic solvent is added, the ion dissociation commonly used in plating does not change.

As this organic solvent, aromatic ones such as toluene, xylene, benzene, etc. are sufficient, but dimethylsulf7oxide, dimethylformamide, γ-butyrolactone, triglyme, etc., which have a high dielectric constant, are preferable.

The blending ratio is 20% by volume based on the total amount of beryllium halotenide and toalkylbiricinium halide.
It is preferable to make it ~80% (therefore, the total amount of molten salt will also be from 20 to 80%). The blending ratio of organic solvent is 20V
If it is less than 80 Vol%, the properties of the bath will be almost the same as those without it, and if it exceeds 80 Vol%, the concentration of beryllium halide in the bath will be low, resulting in poor current efficiency during Be electrodeposition. There is a risk of a fire if the bath temperature rises and ignites.

Plating baths are safe even when exposed to oxygen or moisture, but Be
In order to prevent complex ion oxidation, it is preferable to carry out the reaction in a dry oxygen-free atmosphere (for example, in dry N2 or ^r). Moreover, when electrolysis is carried out at a bath temperature of 0 to 200° C. and a direct current or pulsed current of 0.1 to 10^/dII12, highly pure and uniform plating can be performed efficiently. Bath temperature is 0
If it is lower than ℃, it will be difficult to plate with high current density, and conversely, if the bath temperature is higher than 200℃ and the current density is 10^
If it is higher than /dm2, the crystals become coarse dendrite crystals, resulting in poor appearance and workability. Pulsed current produces finer crystals and better workability than direct current.

Generally, in order to achieve uniform plating through continuous plating, it is necessary to replenish Be ions to the plating bath and control the plating metal ions in the bath at a constant level. This is convenient because Be ions are automatically replenished according to the amount of electrolysis depending on the amount of current applied.

When performing continuous plating using an insoluble anode such as Ti-PL, replenishment of Be ions is performed using BeCl 2 or B
A halide such as eF 2 may be replenished. However, in the case of continuous plating using an insoluble anode, a halogen bus generation reaction occurs at the anode interface during electrolysis, reducing the halogen component in the bath. As a result, the bath composition fluctuates and the bath life is shortened.

The present invention will be explained below with reference to Examples.

(Example) Example 1 A copper plate (plate thickness 0.5III) was subjected to plating pretreatment such as alkaline degreasing and pickling by a conventional method, then dried and immediately kept in a Nzf gas atmosphere in advance.BeC1
□50 mol% and butylpyridinium chloride 50 mol%
Beryllium plating was performed by immersing the material in a molten salt bath consisting of. The plating was carried out for 5 minutes at a bath temperature of 100°C and a DC current density of 5^/dm2, using the copper plate as a cathode and the beryllium plate as an anode.

The plating layer of the obtained beryllium-plated copper plate had a uniform thickness, a metallic luster, and dense crystals. Further, even when the copper plate was repeatedly bent, no cracks or peeling occurred, and both workability and adhesion were good.

Further, the current efficiency was calculated from the amount of current applied and the amount of plating deposited, and was approximately 100%.

Example 2 Using a molten salt bath in which the mixing ratio was 260 mol % of BeF and 40 mol % of methylpyrinonium fluoride, a copper plate of the same thickness was electrolytically plated in the same manner as in Example 1. For plating, keep the bath in a gas atmosphere and keep the bath temperature 1.
The test was carried out at 20° C. and a DC current density of 3^/da2 for 10 minutes.

The properties of the plating layer of the obtained plated copper plate were similar to those in Example 1, and the current efficiency was about 95%.

Example 3 Electrolytic beryllium plating was applied to a copper plate of the same thickness in the same manner as in Example 1 using the molten salt bath of Example 1 to which dimethyl sulf7oxide was added in a proportion of 50 vol%. went. Plating was carried out for 5 minutes at a bath temperature of 50° C. and a DC current density of 7^/d×2 while maintaining the same 82ffX atmosphere.

The properties of the plating layer of the final copper plate obtained in this example were also similar to those in Example 1, and the current efficiency was about 97%.

Example 4 At the end of plating in Examples 1 to 3, beryllium plating was performed by changing the current to a pulsed current. For plating with pulsed current, the duty ratio is 1/ for any plating bath.
10 to 1/100, average current density 0.1 to 10^/dm
However, the thickness of the plating layer was uniform, and the crystals and workability were the same as those obtained by direct current plating.

The same applies to Ni plates and cold-rolled steel plates! ! We tried beryllium plating in our laboratory, and found that excellent beryllium plating was possible.

Although examples have been given above regarding the method for plating materials, the same method can be used for manufacturing electrolytic foil.

(Effects) As described above, according to the present invention, uniform and smooth beryllium plating can be performed at a relatively low temperature and at a high current density.

Claims (3)

[Claims] (1) Beryllium halide (BeX_2) 30-9
0 mol% and alkylpyridinium halide (C_5H_5N-RX, where R is an alkyl group having 1 to 5 carbon atoms, X is a halogen atom) 10 to 70 mol%, or 20 to 80 vol% of an organic solvent is blended with these. Electric beryllium plating bath. (2) Beryllium halide (BeX_2) 30-9
0 mol% and alkylpyridinium halide (C_5H_5N-RX, where R is an alkyl group having 1 to 5 carbon atoms, X is a halogen atom) 10 to 70 mol%, or 20 to 80 vol% of an organic solvent is blended with these. Electric beryllium is characterized by plating using an electrolytic beryllium plating bath under electrolytic conditions of a bath temperature of 0 to 200°C and a current density of 0.1 to 10 A/dm^2 with direct current or pulsed current in a dry oxygen-free atmosphere. Plating method. (3) The electrolytic beryllium plating method according to claim 2, characterized in that plating is performed using a beryllium anode as an anode.