KR20060090816A - Electrolyte for the galvanic deposition of aluminum-magnesium alloys - Google Patents

Abstract

The invention relates to an electrolyte for the galvanic deposition of aluminum-magnesium alloys, which comprises at least one aluminum-organic complex compound of the formula MAIR4 or mixtures thereof and a magnesium alkyl compound, wherein M represents Na, K, Rb or Cs and R represents a C1 to C10 alkyl group, preferably a C 1 to C4 alky group. The invention also relates to a method for producing an electrolyte, to a coating method, the use of the electrolyte and to an electrolysis kit.

Description

Electrolyte for the Galvanic Deposition of Aluminum-Magnesium Alloys

The present invention relates to an electrolyte for galvanic deposition of an aluminum-magnesium alloy, comprising at least one organoaluminum complex and an alkylmagnesium compound. The present invention also relates to a method for preparing the electrolyte, a coating method, the use of the electrolyte and an electrolysis kit.

Recently, magnesium-aluminum-organic complexes have been used for the electrolytic deposition of aluminum-magnesium alloys, which are disclosed in WO 00/32847 A1. Due to the excellent corrosion protection by the aluminum-magnesium layer and its ecological safety, interest in the electrolytic coating of metallic materials with aluminum-magnesium alloys is rapidly increasing. Accordingly, the electroplating method using magnesium-aluminum-organic electrolyte in the temperature range of 60 to 150 ℃ in a closed system has a major technical significance.

WO 00/32847 A1 discloses particularly suitable electrolytes, complexes represented by the general formula MAlR ₄ and mixtures thereof in combination with aluminum alkyl AlR ₃ . They are used in the form of solutions dissolved in liquid aromatic hydrocarbons. In this case, M represents an alkali metal such as sodium, potassium, rubidium and cesium, and R represents an alkyl group having 1, 2 or 4 carbons, respectively.

However, there are significant drawbacks when using such electrolytic systems. The systems known to date do not require the first necessary organic magnesium complex in the electrolyte, and at the time of using the electrolyte, its complex in situ electrochemical production process is required. Therefore, ready-to-use starting mixtures do not contain magnesium compounds, only organoaluminum compounds. For example, in M ² AlR ₄ of these starting mixtures For M ¹ AlR ₄ The molar ratio has a general composition of 1: 0.1 to 0.1: 1: wherein M ¹ and M ² are different from each other and are sodium, potassium, rubidium and cesium, preferably sodium and potassium. AlR ₃ / (M ¹ AlR ₄ + The molar ratio of all components of the M ² AlR ₄ ) / aromatic hydrocarbon is in the range of 1: 0.1: 1 to 1: 2: 10, preferably 1: 1: 3 to 1: 1: 5.

In such electrolytes, the starting electrolyte described above without magnesium is initially placed in an electrolytic bath suitable for coating. Then, using the separate aluminum and magnesium anodes or the aluminum-magnesium mixed electrode until the concentration of the magnesium complex required for coating in the electrolyte is reached, the required organic magnesium compound is immediately in situ. ) Is produced electrochemically.

In addition, the deposition of the aluminum-magnesium layer in the system already occurs before the magnesium complex reaches the required concentration, which is undesirable because it does not have the proper composition of aluminum and magnesium. For this reason, in order to collect the deposited aluminum-magnesium layer, a dummy metal sheet must be present in the system. Deposition on the metal plate proceeds until the aluminum-magnesium complex reaches the required concentration. Then, the metal plate is removed and the desired layer having the desired aluminum-magnesium composition (eg, aluminum: magnesium composition 75:25 mol%) is deposited on the substrate. The metal plate is discarded or washed for later use.

As mentioned above, it can be readily seen that this process is quite complex and requires a long preparation time to reach the desired aluminum-magnesium concentration. In addition, the loading, removing and cleaning of the used metal sheet takes place as an additional process. For this reason, the electrolytes known to be particularly effective described in WO 00/32847 A1 can only be used through the electrochemical generation of organomagnesium complexes in the conditioning phase prior to the actual coating, including all the disadvantages mentioned above. .

In addition, it is also well known in the prior art document WO 00/32847 A1 that the direct adjustment of the magnesium compound in the corresponding amount to the electrolyte can be omitted. Here, Mg [Al (Et) ₄ ] ₂ , a magnesium-aluminum alkyl complex, was used for the electrolyte. This method can be carried out on a laboratory scale, but has the drawback that it cannot be carried out industrially because the complex is not industrially useful, its manufacturing process is quite complicated and expensive.

Economically and efficiently, electrolytes suitable for industrial production of coating substrates with aluminum-magnesium alloys are unknown to date. Further development of electrolytes for galvanic deposition of aluminum-magnesium alloys is of great technical value and is of great interest in terms of economics and ecology.

The technical object of the present invention, after all, does not require the above-mentioned conditioning phase for forming the organo magnesium complex, and can be produced simply and efficiently at low cost, which enables commercial introduction of the aluminum-magnesium coating process. To provide an electrolyte.

The technical object is achieved by an electrolyte for galvanic deposition of an aluminum-magnesium alloy comprising at least one organoaluminum complex represented by the general formula MAlR ₄ or a mixture thereof and an alkylmagnesium compound, wherein M is sodium, potassium, Rubidium or cesium; And R represents a C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₄ alkyl group. Especially more preferably, the electrolyte further comprises trialkylaluminum.

Most preferably, AlR ₃ , M ¹ AlR ₄ , M ² AlR ₄ And an electrolyte comprising Mg (R ¹ ) _x (R ² ) _y wherein M ¹ and M ² are different from each other and represent sodium, potassium, rubidium or cesium; R represents a C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₄ alkyl group; R ¹ and R ² are each independently C ₁ -C ₂₀ Alkyl groups, preferably C ₂ -C ₁₀ An alkyl group; x is 0 to 2; y is 0 to 2; And x + y is two.

Surprisingly, the electrolyte of the present invention does not require in situ production of organomagnesium complexes in the time and costly adjustment steps that precede the actual coating process, but rather to coat the materials with an aluminum-magnesium alloy. Can be used.

Preferably, the alkylmagnesium compound is included in the electrolyte in an amount of 0.01 to 10 mol%, preferably 0.1 to 1 mol% with respect to the aluminum complex. In particular, preferred alkylmagnesium compounds used in the electrolyte are magnesium butyl _{1 . 5-octyl 0 0.5}

_{(Mgbutyl 1 .5 octyl 0 .5)} , magnesium _{butyl-1. 0} ethyl _1.0 (Mgbutyl _1.0 ethyl _1.0), sec- butyl magnesium _1.0

It is selected from n- butyl _{1 .0 (Mgsec-butyl 1 .0} n-butyl 1 .0) , and the group consisting of a mixture thereof.

The organoaluminum complex compound and the alkylmagnesium compound are preferably present in the organic solvent. Especially preferably, the organic solvent is an aromatic solvent such as benzene, toluene or xylene or mixtures thereof.

Compared with the magnesium-aluminum ethyl complex Mg [Al (Et) ₄ ] _{2 described} above, the alkylmagnesium compound defined above has the advantage of enabling industrial usefulness and easy and low cost production. The electrolyte is prepared according to the following steps. First, an organoaluminum complex represented by the general formula MAlR ₄ or a mixture thereof is optionally fed in combination with trialkylaluminum. Following this step, an alkylmagnesium compound is added as described above. M and R have the same meaning as above. The metering of alkylmagnesium during electrolyte preparation has the advantage of directly controlling the required concentrations of magnesium and aluminum, making it possible to produce the electrolyte completely without the previously defined adjustment steps. Furthermore, alkylmagnesium compounds may be added during the coating process to maintain the appropriate magnesium concentrations needed for coating.

According to a preferred embodiment, the alkylmagnesium compound is a mixed alkylmagnesium compound represented by the general formula Mg (R ¹ ) _x (R ² ) _y wherein R ¹ and R ² are each independently C ₁ -C ₂₀ Alkyl groups, preferably C ₂ -C ₁₀ An alkyl group; x is 0 to 2; y is 0 to 2; And, x + y is two. According to a preferred embodiment, the alkylmagnesium compound is added to the hydrocarbon to dissolve and the alkylaluminum complex compound is fed to the aromatic hydrocarbon to dissolve. Hydrocarbons for aluminum compounds are i-pentane, n-pentane, hexane, n-hexane, heptane, n-heptane, toluene and xylene.

Using the electrolyte according to the present invention, aluminum-magnesium layers with different concentrations of aluminum and magnesium can be produced in a single operation by simply and freely selecting the amount of organomagnesium compound applied. Appropriate concentrations of aluminum-magnesium can be controlled by the added amount of organomagnesium compound. In addition, the electrolyte of the present invention has the advantages of excellent conductivity and uniform throwing power.

The electrolyte of the present invention allows the operation of indifferent anodes for use in geometrically complex shaped coatings. The irradiated electrode is not composed of aluminum or magnesium or an alloy thereof, and therefore does not dissolve during the coating process. When coated with a tube electrode, the organomagnesium and organoaluminum compounds must be metered in the electrolytic solution. Appropriate aluminum-magnesium concentration is adjusted via the amount of organomagnesium compound and organoaluminum compound applied. In the prior art, in principle, working as an irradiating electrode for the in situ production of organomagnesium complexes which can be applied to the production of layers with different aluminum-magnesium compositions in a single operation is excluded. This is not even possible in the in situ process described above using a tuning step to provide magnesium concentration in the electrolyte.

In addition, the present invention (i) an organoaluminum complex or alkylaluminum compound disclosed in claims 1 to 3; And, (ii) an electrolysis kit for galvanic deposition of an aluminum-magnesium alloy on an electrically conductive material or an electrically conductive layer comprising the alkylmagnesium compound as defined in claims 1, 3, 5 and 6. To provide.

According to a preferred embodiment, the compounds of (i) and (ii) are dissolved in an organic solvent.

In addition, the present invention provides a method for claiming, during the coating step, in order to formulate or maintain the desired concentrations of magnesium and aluminum, the desired amount of the alkylmagnesium compound as defined in claims 1, 3, 5 and 6, A method of coating an electrically conductive material or layer with an aluminum-magnesium alloy using the electrolytes disclosed in claims 1 to 9.

The present invention also provides the use of an electrolyte disclosed in the invention for producing an aluminum alloy layer over an electrically conductive material or electrically conductive layer.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1: Use of which 20% Mgbutyl _{1 .5 0 .5} octyl (BOMAG Crompton Corporation ^® products) dissolved in heptane

The whole reaction was carried out under the protection of argon gas.

Step 1: Concentrated to remove heptane, then BOMAG ^® / heptane solution was adjusted to 0.32 mmol / g with toluene.

Step 2: 0.8 K [Al (Et) ₄ ] + 0.2 Na [Al (Et) ₄ ] + 1.17 Al (Et) ₃ + 3.85 55.4 g of an electrolyte containing toluene was added to 2.85 g of a BOMAG / toluene solution (1.0 for electrolyte). Mole%).

About 58 g of electrolyte was obtained.

Coating inspection :

General conditions:

All deposition experiments were performed under standard conditions. The magnesium component was pipetted directly into the electrolyte.

Anode material: 2 alloy electrode, aluminum-magnesium, 25.55 x 10 x 5 mm

Cathode: hexagonal screw, 8.8, M8 x 25

Cathode pretreatment: grease and descaling in an ultrasonic bath containing 8% HCl. Washed with water, vacuum dried and stored under argon gas

Cathode Settling Depth: Fully Locked

Cathode Rotation: 60rpm

Distance to anode: 10 mm

Effective cathode surface: 10 cm ²

Bath agitation: 250 rpm, 2 cm magnet in glass jacket

Bath temperature: 94-98 ℃

Deposition began with a current density of 0.05 A / dm ² . After a few minutes a bright overlay was seen in the area to be coated. The current density was gradually increased to 3.0 A / dm ² . After the current amount corresponding to the layer thickness of 5 mu m became 1.499 mF, the deposition was finished. The layer is bright and silver white.

RF analysis of layer: magnesium 26.79 mass%, aluminum 73.21 mass%

Example 2: Use of which _{20% Mgethyl 1 .0 butyl 1 .0} (Akzo-Nobel , Inc. BEM, Ltd.) dissolved in heptane

The reaction was carried out under the protection of argon gas.

Step 1: Concentrated to remove heptane, then BEM / heptane solution was adjusted to 0.41 mmol / g with toluene.

Step 2: 0.8 K [Al (Et) ₄ ] + 0.2 Na [Al (Et) ₄ ] + 1.17 Al (Et) ₃ + 3.85 60.6 g of an electrolyte containing toluene 2 ml of a BEM / toluene solution (0.9 mol to electrolyte) %). About 62 g of electrolyte was obtained.

Coating inspection :

Deposition conditions were the same as in Example 1. Deposition began immediately with a current density of 2.0 A / dm ² , which remained unchanged during the entire electrolysis. Instantaneous bright deposition of aluminum / magnesium proceeded. After the current amount corresponding to the layer thickness of 11 mu m became 3.38 mF, the deposition was finished. A very uniform silvery white layer was obtained without defects.

RF analysis of the layers: 26.78 mass% magnesium, 73.22 mass% aluminum

Example 3: use of iso-pentane (isopentane) was _{20% Mgethyl 1 .0 butyl 1 .0} (Albemarle Corporation BEM, Ltd.) dissolved in

The reaction was carried out under the protection of argon gas.

Step 1: A BEM / isopentane solution containing 1.85 mmol / g magnesium was used without further pretreatment.

Step 2: 0.85 K [Al (Et) ₄ ] + 0.15 Na [Al (Et) ₄ ] + 1.08 Al (Et) ₃ + 3.15 70.04 g of an electrolyte containing toluene was added to 0.5 g of BEM / isopentane solution (for electrolyte , 0.8 mol%).

Coating inspection :

Deposition conditions were the same as in Example 1. Deposition was carried out at a current density of 1.0 to 3.0 A / dm ² . After the current amount corresponding to the layer thickness of 20 m became 6.8 mF, the deposition was finished. A very uniform silvery white layer was obtained.

RF analysis of layers: magnesium 41.4%, aluminum 58.9%

Comparative Example 1 : Using Albemarle's electrolyte without direct addition of magnesium-alkyl solution (regulated electrolyte) for aluminum-magnesium deposition

0.8 K [Al (Et) ₄ ] + 0.2 Na [Al (Et) ₄ ] + 1.17 Al (Et) ₃ + 3.85 65.0 g of an electrolyte containing toluene, except for the previous addition of magnesium-alkyl solution Mg complexes must be electrochemically produced in the conditioning step before use of the electrolyte in the deposition of aluminum-magnesium alloys, as previously required in the art, using preparatory conditioning under the aforementioned general conditions. do.

Adjustment Step 1: electrolysis starting with the first 0.05A / dm ^2, was carried out at a current density is increased to a maximum of 1.0A / dm ^2. After a current density of 7.20 mF, a pale gray coating was obtained, which had a weak uniform power.

Adjustment step 2: After replacing the positive electrode, adjustment was continued at 1.0 to 1.2 A / dm ² . After a current density of 7.24 mF, a distinctly bright and weakly glossed section was obtained with a slight improvement in uniform electrodeposition.

Adjustment step 3: After changing the anode again, the maximum allowable current density is 1.23A / dm ² and above 1.5A / dm ² To 2.0 A / dm ² to obtain a uniform glossy coating with significantly improved uniform electrodeposition. The amount of current was 4.96 mF.

Adjustment step 4: A final adjustment was reached, giving a glossy coating with a current density of 3.0 A / dm ² with the same uniform electrodeposition as compared with adjustment step 3. The current amount was 3.73 mF.

Electrolysis is controlled and manipulated only after this process.

Claims (20)

Electrolyte for galvanic deposition of an aluminum-magnesium alloy comprising at least one organoaluminum complex represented by the general formula MAIR ₄ or a mixture thereof and an alkylmagnesium compound: Where                   M represents sodium, potassium, rubidium or cesium; And, R represents a C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₄ alkyl group. The method of claim 1, Electrolyte further comprises trialkylaluminum Electrolyte. The method according to claim 1 or 2, The electrolyte is AlR ₃ , M ¹ AlR ₄ , M ² AlR ₄ And Mg (R ¹ ) _x (R ² ) _y Characterized Electrolyte: Where M ¹ and M ² are different from each other and sodium, potassium, rubidium or cesium Represent; R represents a C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₄ alkyl group; R ¹ and R ² are each independently C ₁ -C ₂₀ Alkyl groups, preferably C ₂ -C ₁₀                 An alkyl group;                 x is 0 to 2; y is 0 to 2; And,                 x + y is two. The method according to any one of claims 1 to 3 or more, Alkali magnesium compound is 0.01 to 10 relative to the aluminum complex Mole%, preferably from 0.1 to 1 mole% Electrolyte. The method according to any one of claims 1 to 4 or more, The alkyl magnesium compound is magnesium butyl _{1 . 5-octyl-0 .5 (Mgbutyl 1 .5 octyl 0} .5), Magnesium Butyl _{1 . 0} ethyl _{1 .0 (Mgbutyl 1 .0 ethyl 1} .0), Magnesium sec- butyl-n- _{butyl-1 .0 1 .0 (Mgsec-butyl 1 .0} n-butyl 1 .0) , and, Selected from the group consisting of mixtures thereof Characterized Electrolyte. The method according to any one of claims 1 to 5 or more, The electrolyte comprises an organic solvent Electrolyte. The method of claim 6, The organic solvent is characterized in that the aromatic solvent Electrolyte. The method of claim 7, wherein The aromatic solvent is benzene, toluene or xylene or mixtures thereof Characterized Electrolyte. (i) optionally feeding the organoaluminum complex represented by the general formula MAlR ₄ or a mixture thereof in combination with trialkylaluminum; And, (ii) adding an alkylmagnesium compound, the method of producing an electrolyte according to claim 1 to 8, comprising the steps of: Where                   M represents sodium, potassium, rubidium or cesium; And, R represents a C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₄ alkyl group. The method of claim 9, The organoaluminum complex is M ¹ AlR ₄ And M ² AlR ₄ . Way: Where M ¹ and M ² are different from each other and sodium, potassium, rubidium or cesium Represent; And, R represents a C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₄ alkyl group. The method of claim 9, Alkali magnesium compound is characterized in that Mg (R ¹ ) _x (R ² ) _y Way: Where R ¹ and R ² are each independently C ₁ -C ₂₀ Alkyl groups, preferably C ₂ -C ₁₀ An alkyl group;                  x is 0 to 2; y is 0 to 2; And,           x + y is two. The method according to any one of claims 9 to 11 or more, The alkyl magnesium compound added is dissolved in a hydrocarbon. doing Way. The method according to any one of claims 9 to 11 or more, The supplied alkylaluminum complex is dissolved in aromatic hydrocarbons Characterized Way. The method of claim 12, Characterized in that the hydrocarbon is a saturated or unsaturated hydrocarbon Way. The method of claim 14, Hydrocarbons include i-pentane, n-pentane, hexane, n-hexane, heptane, n-heptane, toluene and Xylene is selected from the group consisting of Way. An electrolyte for producing an aluminum-magnesium alloy on an electrically conductive material or an electrically conductive layer prepared by the method as claimed in claim 9. A method of coating an electrically conducting material or layer with an aluminum-magnesium alloy, while metering an alkylmagnesium compound, using the electrolytes described in claims 1-8. Use of the electrolytes disclosed in claims 1 to 8 and 16 for the production of an aluminum-magnesium alloy layer on an electrically conductive material or layer. (i) the organoaluminum complex or alkylaluminum compound of claims 1 to 3; And (ii) an electrolysis kit for galvanic deposition of an aluminum-magnesium alloy on an electrically conductive material or layer comprising the alkylmagnesium compound of claims 1, 3 and 5. The method of claim 19, Compounds (i) and (ii) are present in the organic solvent Electrolysis kit.