JPS636997B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an aluminum busbar. In particular, the present invention relates to an aluminum busbar with improved electrical contact between conductor connections and contact surfaces with plugs. Note that the term "aluminum" used in this specification means aluminum and its alloys. Copper conductors have traditionally been used in busbars, but due to the instability of copper resources, supply, and prices, a shift to aluminum conductors is underway.
However, when using aluminum busbars, there are concerns such as corrosion at the connection with the copper conductor and an increase in contact resistance at the contact surface with the copper or aluminum conductor. is being painted. In addition, in order to omit such work and prevent accidents due to work errors, it is common practice to apply zincate treatment to the connections of aluminum busbars, then copper plating, and then tin or silver plating on top of that. are doing. Aluminum busbars plated with tin or silver using the zincate method can be used without special treatment prior to construction in locations where they are not exposed to extremely corrosive atmospheres or high temperatures. However, the conventional structure requires a very large number of plating steps, as shown in Comparative Example 1, which will be described later. In addition, in the conventional structure, since it has a copper strike and an underplating layer, once the aluminum substrate and/or the zinc substitution layer are exposed, the aluminum or zinc undergoes significant corrosion due to contact corrosion with the copper. The drawback is that the velvet swells. In addition, if the plug is used in a highly corrosive environment or at high temperatures, or if the plug becomes loose or the bolts are insufficiently tightened when connecting to other conductors, the resistance of the contact area will increase and cause overheating. There is danger. Another drawback of the conventional structure is that the copper plating solution used in its manufacture is strongly alkaline with a pH of 12 or higher, so if there is even a slight defect in the zincate layer, the aluminum will dissolve and the copper plating will fail. During this process, the plating layer often swells, which is a problem that often occurs. Furthermore, the conventional construction has the disadvantage that the plating solution used during its manufacture contains highly toxic cyanide.

In view of the above-mentioned drawbacks of the conventional methods, the object of the present invention is to provide a structure for an aluminum busbar that does not have any of these drawbacks.

The aluminum busbar of the present invention has 1 to 50% nickel on the connection part with the conductor and the contact surface of the plug.
It was directly electroplated at a rate of mg/cm ² . That is, the aluminum busbar of the present invention is treated with hydrochloric acid 5 to 35% as a pretreatment for nickel plating.
%, and then directly apply nickel at a rate of 1 to 50 mg/cm ² to the conductor connections and plug contact surfaces using a plating solution containing 50 g or more of nickel ions as sulfamate or borofluoride. It can be obtained by a method for producing an aluminum busbar characterized by applying nickel plating.

In order to produce the aluminum busbar of the present invention, first, the connections of the busbar are prepared using a solution containing 5 to 35% hydrochloric acid, preferably 10 to 20% hydrochloric acid, nitric acid and/or
Alternatively, etching is performed with a solution containing 0.5 to 1% sulfuric acid for 5 seconds to 2 minutes, preferably 30 seconds to 1 minute. Thereafter, it is washed with water and plated with a sulfamic acid nickel plating solution or a borosified nickel plating solution containing 50 g or more of nickel ions. The structure of the aluminum busbar according to the present invention is such that nickel is directly adhered to aluminum having significant microscopic irregularities at a rate of 1 to 50 mg/cm ² , preferably 5 to 20 mg/cm ² at the connection part. It is becoming.

If the hydrochloric acid is less than 5% or the etching time is less than 5 seconds, the entire surface will not be etched and the plating will be uneven, resulting in poor corrosion resistance and high contact resistance when used as a bus bar. If hydrochloric acid exceeds 35%, gas will be generated significantly, and if the etching time exceeds 2 minutes, the production speed will slow down.
Below this, the electrodeposition speed becomes too low and the plating time becomes too long, making it impossible to apply in actual operation.
Plating liquids other than sulfamic acid nickel plating baths or phosphorous nickel plating baths do not adhere well to the plating and cannot be used as busbars. If the amount of nickel plating is less than 1 mg/cm ² , there is a problem in using it as a bus bar in terms of corrosion resistance, and if it exceeds 50 mg/cm ² , a large amount of nickel, which is more expensive than aluminum, will be used, resulting in an excessively high cost.

In the specific implementation of the present invention, an aluminum plate manufactured by rolling or extrusion is cut into a desired size, and then polished, degreased, etc. are performed as necessary, and then the joints are etched with alkali. do. As an alkaline etching solution,
For example, a solution of caustic soda, soda carbonate, etc. is used, and in some cases, a solution containing a surfactant such as sodium gluconate is used. Next, wash with water,
The joints are etched with the aforementioned solution containing 5 to 35% hydrochloric acid, then washed with water and nickel plated. Normally, in order to treat only the connecting surface, etching and plating are performed by immersing only the connecting surface in liquid, but for the same purpose, parts other than the connecting portion are coated with paint, vinyl tape, rubber, etc. It may be coated in advance. The nickel sulfamic acid plating solution preferably contains nickel chloride and boric acid in addition to the nickel sulfamic acid, and the nickel borosulfate plating solution preferably contains boric acid in addition to the nickel borosulfate. Further, the production of the aluminum busbar of the present invention can be operated manually, semi-automatically or automatically.

As shown in Example 1 below, the aluminum busbar of the present invention has a significantly shorter manufacturing process than those with a conventional structure, does not use any cyanide, and nickel is directly applied to the aluminum surface. Because it is plated, even if the aluminum base is exposed, contact corrosion is much smaller than with conventional products. Furthermore, since nickel has better oxidation resistance than copper and has less interdiffusion with aluminum, the phenomenon of a significant increase in contact resistance during use at high temperatures, unlike conventional products, does not occur. Further, as a result of a current cycle test, it was found that the aluminum busbar of the present invention has very stable contact resistance. This seems to have something to do with the fact that in the manufacturing method, when etching the aluminum, significant unevenness is created, and even when plating is applied on top of it, the surface of the plating is left with significant unevenness. Details are not clear.

Next, examples of the present invention will be described.

Example 1 A bare conductor three-pole feeder bus duct was manufactured from an extruded A1060-F aluminum plate with a thickness of 10 mm, a width of 200 mm, and a length of 5 m. At that time, after extruding the conductor, the connection part was etched for 1 minute in a 60°C solution consisting of 30 g of caustic soda and 30 g of soda carbonate, and then washed with water.
Next, it was etched for 1 minute with a solution consisting of 16% hydrochloric acid and 1% nitric acid, washed with water, and then etched with Ni(SO ₃ NH ₂ ) ₂ .
4H ₂ O 320g/, NiCl ₂・6H ₂ O 15g/,
It was immersed in a 50°C plating solution containing 30 g of H ₃ BO ₃ and plated for 5 minutes at a current density of 5 A/dm ² .
Approximately 4.6 mg/cm ² of nickel was obtained. Thickness 10mm,
Approximately 4.6 mg/cm ² of nickel plating was applied to a patch plate made of the same material with a width of 200 mm and a length of 150 mm using the same method.
This patch plate was inserted between each conductor of the two sets of bus ducts, and the connections were made using galvanized copper bolts, nuts, and washers. While measuring the temperature of the connection using a thermocouple, a current of 3000A at 600V was applied for 45 minutes.
The power supply was stopped for 45 minutes. When this was repeated 1000 cycles, the maximum temperature increase was 30°C, which was very small.

Example 2 A bus duct with a tap was manufactured from an A1060-H14 aluminum rolled plate having a thickness of 4 mm, a width of 25 mm, and a length of 2 m. After rolling, straightening, and cutting, wash with trichlorethylene, and add 50 g of caustic soda to the tap area.
Etched for 2 minutes with a solution of 3 g of sodium gluconate at 50°C, washed with water, etched with a solution containing 15% hydrochloric acid and 0.5% sulfuric acid, washed with water, and etched with the same plating solution as in Example 1 at 50°C. bath temperature, 8A/d
Plating was performed for 10 minutes at a current density of m ² to give a nickel plating of about 14.6 mg/cm ² . A 2.6 mmφ vinyl copper-covered wire was connected to the tap using a brass terminal screw, and a current of 50 A was applied. Maximum temperature rise is 27℃
So, it was small.

Example 3 A1060-H14 with thickness 0.8 mm, width 10 cm, and length 0.5 m
Manufactured a bus duct adapter made of rolled aluminum plate. Wash 7cm from both ends with trichlorethylene, etch for 1 minute with a solution at 60°C containing 50g of caustic soda, wash with water, and etch with a solution of 18% hydrochloric acid to form a plating made of 650g of borosilicate nickel/30g of boric acid. It was plated with a liquid for 2 minutes at a current density of 10 A/dm ² to give a nickel plating of about 3.7 mg/cm ² . A salt spray test was conducted at 35°C with 5% NaCl for 72 hours, but no corrosion occurred.

Comparative Example 1 A bus duct of the same type as Example 1 was manufactured using a conventional method. However, the surface treatment of the connection part is done by the conventional zincate method, and after extrusion, 30 g of caustic soda/
, etched with a solution at 60°C consisting of 30 g of soda carbonate, washed with water, immersed in a 50% nitric acid solution for 10 seconds, and zincated by immersed in a solution of 525 g of NaOH and 100 g of ZnO for 1 minute.
Rinse with water and remove from copper cyanide strike plating bath at 40°C.
Plated for 1 minute at a current density of 2.6A/ ^dm2 , washed with water, and then plated with a cyanide copper plating solution (89℃).
Plating was carried out at 4 A/dm ² for 5 minutes, and then 5 μm tin plating was applied from a stannate bath. A backing plate made of the same material and having the same shape as in Example 1 was also tin-plated using the zincate method. When these bath ducts and accessories were tested in the same manner as in Example 1, the maximum temperature increase reached 120°C.

Comparative Example 2 An adapter of the same type as in Example 3 was manufactured. After washing with trichlorethylene, the same etching, pickling, and zincate treatments as in Comparative Example 1 were applied to 7 cm from both ends.
Copper strike plating was applied, and nickel plating was applied thereon in the same manner and for the same time as in Example 3.
When the same salt spray test as in Example 3 was conducted,
Blisters occurred at a rate of 14 blisters/dm ² .

As mentioned above, the aluminum busbar of the present invention has stable electrical contact resistance, excellent corrosion resistance, and is inexpensive, and has great industrial application value.

Claims (1)

[Claims] 1. Aluminum busbar with nickel directly electroplated on the conductor connections and plug contact surfaces at a rate of 1 to 50 mg/cm ² .