KR20010067721A - Method process for forming copper and nickel-plated of electrolytic plating in magnesium compound - Google Patents

Abstract

PURPOSE: A method for forming a copper-nickel plating layer as electro plating on a magnesium alloy is provided to obtain painted magnesium alloy materials having various colors and excellent brilliance, and obtain magnesium alloy materials having strong corrosion resistance, strong abrasion resistance, and high specific strength. CONSTITUTION: A method for forming a copper-nickel plating layer as electro plating on a magnesium alloy includes the steps of treating the magnesium alloy with an active treating agent, directly plating the magnesium alloy with copper plating solution, and directly plating the top side of the copper plating with nickel plating solution in a wet process.

Description

METHOD PROCESS FOR FORMING COPPER AND NICKEL-PLATED OF ELECTROLYTIC PLATING IN MAGNESIUM COMPOUND}

The present invention relates to a method of forming a copper-nickel plating layer on a magnesium alloy by electroplating, and to a magnesium alloy plated by the method, and more particularly, to provide magnesium with strong corrosion resistance to a magnesium alloy having poor corrosion resistance. The present invention relates to a method of forming a copper (Cu) -nickel (Ni) plating layer in an alloy by electroplating, and to a magnesium alloy produced by the method.

In general, magnesium has the advantage of being the lightest metal among structural metals, so it has a great advantage as a structural material, and thus is used in automobile parts, electrical and electronic parts, and information and communication parts.

Magnesium alloys are easy to process, are about 30% lighter than aluminum alloys, and have specific strengths (specific gravity / strength).

However, magnesium alloy has a disadvantage in that the material is vulnerable to both alkali and acid.

Generally, plating is divided into dry plating and wet plating.

Magnesium has a high vapor pressure and cannot be subjected to dry plating by vapor deposition in a vacuum, and magnesium alloy is corroded to both alkali and acid as described above, and is particularly vulnerable to acid. In addition, when contacted with water containing a small amount of salt (NaCl) at room temperature, it generates heat and corrodes very violently.

Wet plating is also difficult to use due to the difficult plating in the surface treatment of magnesium alloy.

Accordingly, as a method of treating magnesium alloy, coating and plating are mainly performed, which will be described below in more detail.

As the coating treatment method, chromate and chemical conversion treatment are typically used.

The coating treatment is used for internal parts that are not very strong corrosion resistance and blocked from the outside or used for pre-painting treatment. In this film formation, chromium (Cr), which is being tightened due to pollution problems, is used, and it is expected to be regulated in future production.

As the plating method, nickel (Ni) -phosphorus (P) plating is used.

In the case of nickel-phosphorus plating on magnesium alloy, the corrosion resistance is different after plating depending on the content of phosphorus, but tends to be relatively strong at low concentration (3%-5%).

However, even at low concentrations of nickel-phosphorus plating, the corrosion resistance is only slightly better than that of the chemical conversion treatment. Therefore, in order to obtain corrosion resistance, nickel-phosphorium plating containing low concentration of phosphorus is carried out, nickel-phosphorus plating containing high concentration of phosphorus is carried out, and then nickel plating is performed again. The nickel plated layer has strong corrosion resistance here. In particular, nickel-phosphorus wet plating of magnesium alloy is an electroless plating method, which is a reality of using an electroless plating method, and thus the electroless nickel-phosphorus plating unit price is very high, so it is very unlikely to be used for commercial purposes.

As mentioned above, the conventional plating method has a limit in improving the beauty, the corrosion resistance, and the abrasion resistance of the case parts of magnesium alloy.

In addition, there is a problem in that the copper plating on the surface of the magnesium alloy difficult to wet plating because it is vulnerable to both acid and alkali.

The present invention has been made to solve the problems as described above, it is possible to electrolytic copper plating on magnesium alloy, it is an object to solve the weakness of the magnesium alloy by plating nickel on the base plating is copper plating.

The present invention is manufactured by plating copper and nickel on a magnesium alloy material which is vulnerable to alkali and acid, so that the magnesium alloy can withstand alkali and acid well and at the same time obtain the light weight, durability, wear resistance and corrosion resistance which cannot be obtained from magnesium alloy. To provide a magnesium alloy.

The present invention is to provide a magnesium alloy by applying a method of electrolytic copper plating to magnesium alloy to increase the adhesion of the underlying plating and to lower the plating cost, and to provide a magnesium alloy with a strong corrosion resistance that can not be obtained from magnesium alloy by plating nickel.

1 is a cross-sectional view showing an example of a colorant of titanium-deposited nonferrous metal in the method of forming a copper-nickel plating layer on the magnesium alloy according to the present invention by electroplating.

2 is a block diagram showing a process of plating copper and nickel in the method of forming a copper-nickel plating layer on the magnesium alloy according to the present invention by electroplating.

<Description of the symbols for the main parts of the drawings>

1: Metal base 2: Copper wet plating layer

3: nickel wet plating layer

The present invention relates to a method of forming a copper-nickel plated layer of magnesium alloy by electroplating.

A copper plating layer formed by plating copper on the upper portion of the magnesium alloy, and a nickel plating layer formed by plating nickel on the upper surface of the copper plating, characterized in that it comprises.

With reference to the accompanying drawings, a method of forming a copper-nickel plated layer of magnesium alloy according to the present invention by electroplating will be understood by the embodiments described in detail below.

1 is a cross-sectional view showing an example of a colorant of titanium-deposited nonferrous metal according to the present invention and Figure 2 is a block diagram showing a process of plating copper and nickel on the magnesium alloy according to the present invention.

According to Figure 1 it can be seen that the wet plating of copper directly on the magnesium alloy base.

Magnesium alloys are very resistant to acid corrosion, making it almost impossible to plate. Copper plating of magnesium alloys is very sensitive to pretreatment (degreasing, pickling, activity) as well as processing.

Especially during this pretreatment, the active treatment has a great influence on the adhesion and uniformity of copper plating.

In order to obtain a uniform and tight copper-nickel plated layer on the magnesium alloy, the pretreatment must be precisely performed, not a constant amount of copper. In short, step-by-step rinsing is thorough.

If the solution from the previous process is mixed with the next process solution, it can interfere with electrochemical plating and cause fatal plating failure.

Copper plating of magnesium alloy is plated with weakly acidic aqueous solution including additives with main components of cyanide copper, sodium cyanide, copper sulfate, and sulfuric acid as a main component to obtain strong adhesion, which is different from the existing copper plating solution.

Nickel plating of magnesium alloy is mainly made of nickel sulfate, ammonium chloride and zinc sulfate to form an aqueous solution.

Using the aqueous solution prepared as described above is wet plating with copper, nickel on the surface of the magnesium alloy. In particular, the shape of the metal base 1 is not limited to any shape.

Hereinafter, embodiments of the present invention will be described in detail.

Magnesium alloy is processed into a die-casting material, and then placed in a 55 ~ 85 ℃ degreasing solution and maintained for about 10 minutes to remove all of the surface oil and degreaser components completely with water.

At this time, if any component of the degreasing solution remains, the electrochemical reaction during plating is lowered, which causes swelling and pinholes to degrade the adhesion between the base metal and the plating layer, and therefore requires thorough washing.

The aqueous solution as shown in the following table is prepared, the temperature of the aqueous solution is adjusted and immersed.

The following is a table showing the temperature and immersion time according to the composition of the aqueous solution.

Aqueous solution composition Aqueous solution temperature (℃) Immersion time (minutes) NaOH + Na ₂ PO ₄ + additive 55-85 3 to 15

It is degreased using the aqueous solution as described above.

Then, after degreasing, an aqueous solution is prepared as shown in the following table to remove the magnesium oxide film, and a mild pickling treatment is performed at room temperature for 3 minutes according to the aqueous solution temperature and the immersion time.

Aqueous solution composition Aqueous solution temperature (℃) Immersion time (minutes) H ₃ PO ₄ + Na ₂ CO ₃ ㆍ 10H ₂ O + HF + Additive 65 to 85 0.5 to 5

Subsequently, an aqueous solution as described below is prepared, and an activation treatment is performed using the following aqueous solution so that the plating process is performed on the pickled magnesium alloy.

Aqueous solution composition Aqueous solution temperature (℃) Immersion time (minutes) pH Na ₄ P ₂ O ₇ + CH ₃ COONa + NH ₃ OH ₅ + Additive 55-80 1 to 2 10 to 11

Thereafter, copper is plated on the magnesium alloy.

First, cyanide copper plating is performed to improve the adhesion of the base metal. The cyanide copper plating layer is formed by adjusting the temperature, voltage, current, and energization time using the following aqueous solution.

Aqueous solution composition Aqueous solution temperature (℃) Voltage (V) Current (A / dm2) Power supply time (minutes) pH CuCN + NaCN + Additive 25 to 35 2 to 4 3 to 5 1 to 5 9-10

After the cyanide copper plating is made, copper sulfate is plated for the removal of the pinholes and the adhesion of nickel plating. At this time, copper sulfate layer is formed by adjusting the temperature, voltage, current, and energization time using the following aqueous solution.

Aqueous solution composition Aqueous solution temperature (℃) Voltage (V) Current (A / dm2) Power supply time (minutes) pH CuSO ₄ + H ₂ SO ₄ + Chlorine + Additive 30-50 4 to 6 5 to 8 1 to 5 9-10

As described above, nickel plating is performed on the surface of the copper plating layer on which the cyanide copper plating and copper sulfate copper plating layers are formed to improve hardness and wear resistance. At this time, an aqueous solution as shown in the following table is formed, and a nickel layer is formed by adjusting temperature, voltage, current, and energization time.

Aqueous solution composition Aqueous solution temperature (℃) Voltage (V) Current (A / dm2) Power supply time (minutes) pH NiSO ₄ + 6H ₂ O + NH ₄ Cl + Zinc Sulfate + Additive 25-40 2.5 to 5.5 0.2 to 1.5 1 to 7 5 to 6

Test specimen Adhesion Pencil lead test (H) Give test Tape testing Example One ○ ○ 4 2 ○ ○ 4 3 ○ ○ 4 4 ○ ○ 4 5 ○ ○ 4 6 ○ ○ 4 7 ○ ○ 4

○) Excellent △: Normal ×: Easily peeled off

Table 1 is a joules test and a tape test of the copper-nickel plated product on the magnesium alloy of the present invention was carried out under the prescribed conditions.

What was clearly shown here was able to obtain uniform gloss without any color bleeding in any of Examples 1-7. In addition, as a general test method, the tape was scratched with a horizontal and vertical tungsten knife at intervals of 1 mm, and no peeling phenomenon was found.

Then do a line test. The joules test is to cut the plated vertically, and fix the test piece to file at a 45 degree angle to the plated surface. (At this time, the coating film should not be peeled off.) As shown in Table 1, all of the joules test results were excellent. appear.

3% NaOH solution Psalm Number One 2 3 4 5 6 7 1 day ○ ○ ○ ○ ○ ○ ○ 2 day ○ ○ ○ ○ ○ ○ ○ 3 day ○ ○ ○ ○ ○ ○ ○ 4 day ○ ○ ○ ○ ○ ○ ○ 5 day ○ ○ ○ ○ ○ ○ ○

Remarks)) ○: Excellent corrosion resistance ×: Elution easily

Table 2 shows that after staining with the prescribed conditions of the present invention, all seven specimens carried out by immersion in a 3% NaOH aqueous solution to confirm corrosion resistance did not proceed with corrosion. Also, no change in gloss and color was seen.

Product 5% NaOH Liquid Psalm Number One 2 3 4 5 6 7 1 day ○ ○ ○ ○ ○ ○ ○ 2 day ○ ○ ○ ○ ○ ○ ○ 3 day ○ ○ ○ ○ ○ ○ ○ 4 day ○ ○ ○ ○ ○ ○ ○ 5 day ○ ○ ○ ○ ○ ○ ○

○) Excellent corrosion resistance ×: Easily eluted

Table 3 shows the corrosion resistance by immersing in 5% NaCl solution. Similarly, in all seven cases no progress of corrosion was observed, and no change in color and gloss was found.

One embodiment of the present invention as described above does not limit the present invention, and modifications within the scope of the foregoing description are included in the technical scope of the present invention as a whole.

According to the present invention, the application of copper, which is commonly used as a base plated layer, to magnesium alloys improves productivity while eliminating fragility of surface treatment of magnesium alloys, and has the advantage of allowing multiple platings to be plated on top of existing base plated layers.

As the shortcomings of the magnesium alloy are solved, the advantages of specific strength can be utilized, so that the field of use has a ripple effect that can be considerably widened.

In addition, the present invention has the effect of obtaining a colored magnesium alloy material excellent in various colors, corrosion resistance and gloss by anodizing the titanium deposited plating layer with a copper and nickel wet plating layer between the titanium deposited plating layer and the magnesium alloy.

In addition, the copper-nickel plated magnesium alloy of the present invention has a high specific strength and has the advantage of obtaining corrosion resistance and wear resistance.

Claims (4)

A method of forming a copper-nickel plating layer on an electrolytic plating on a magnesium alloy, characterized in that the magnesium alloy is treated with an active treatment solution and then directly plated on a matrix using copper and nickel plating solutions. The copper plating pretreatment according to claim 1, wherein the active treatment liquid as copper plating pretreatment is composed of 12-15 g / l Na ₄ P ₂ O ₇ 10-15 g / l CH ₃ COONa, NH ₃ OH and additives. A method of forming a copper-nickel plated layer on an electrolytic plating on a magnesium alloy, which is a phosphorus activation treatment method. The composition of claim 1, wherein the copper plating solution consists of cyanide copper plating (30-60 g / l CuCN, 40-60 g / l NaCN, additive 5%), copper sulfate plating (300-400 g / l CuSO ₄ · 5H ₂ O, 30- 50g / l H ₂ SO _4, 30 ~ 50g / l Chloride additive 2%) method for forming a copper-nickel plating layer on the magnesium alloy characterized in that the electroplating. The method of claim 1, wherein the nickel plating solution comprises 150 g / l NiSO ₄ .6H ₂ O, 15 g / l Na ₄ Cl, A method of forming a copper-nickel plating layer on a magnesium alloy, which is 35 g / l ZnSO ₄ · 7H ₂ O, 10 g / l, by electroplating.