JPS61291961A - Manufacture of metallic strip having brass coating layer - Google Patents

Abstract

PURPOSE:To easily obtain a metallic plate having a brass layer as the outermost layer without deteriorating the properties of the base metal by vacuum- depositing Zn on a metallic strip having a Cu surface and by heat treating the Zn plated strip at a prescribed temp. CONSTITUTION:Zn is vacuum-deposited on a metallic strip of Cu or a Cu plated metal. This Zn plated strip is heated to 250-420 deg.C to diffuse the Zn and Cu. Thus, a metallic plate having a brass layer as the outermost layer is easily obtd. without deteriorating the properties of the base metal.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to copper or copper-plated metal strips (plates).
This method relates to a method of obtaining a brass-plated metal strip (plate) by vacuum-evaporating zinc on a metal plate and then performing a diffusion treatment to form a brass layer.

<Prior art> Brass, that is, a copper alloy containing less than 50% zinc, has a beautiful golden color, is relatively strong, is easy to braze, and has good corrosion resistance, so it is widely used. Its thin plates are widely used. In order to impart the characteristics of brass and golden color to steel and other metal materials, there is a method of plating brass.

Brass plating may be hot-dip plating or electroplating.

However, in hot-dip brass plating on metal materials such as steel plates, for example, 40% Zn-60% Cu brass has a high melting point of about 900° C., so there are problems as described below.

1) It is difficult to manufacture plating equipment that can withstand the high melting point of brass.

2) Since the material to be plated is exposed to high temperatures during plating, the mechanical properties of the material itself are affected.

Electroplating is also widely used as a brass plating method. In other words, electrodeposition is performed in an electrolytic solution containing copper cyanide, zinc cyanide, and potassium cyanide as main components, but the use of cyanide, which is a hazardous substance, requires enormous equipment and expense to prevent pollution. In addition to the general disadvantages of chemical processing, such as controlling the concentration of each component, controlling the temperature of the electrolyte, and controlling the pH, in order to simultaneously electrodeposit copper, which is a negative metal, and zinc, which is a base metal, it is necessary to There are too many conditions to be met,
The tolerance range is extremely narrow, and the current density is IA/dm.
Since it is small (less than 2), it is of poor industrial utility.

JP-A No. 58-39795 discloses a brass layer in which the object to be plated is plated with copper and zinc separately in that order, and then heated at a predetermined temperature to diffuse the copper and zinc. A plating method has been proposed. This specification does not specifically mention any means of galvanizing, especially considering that there is no mention of vacuum evaporation plating and the fact that this type of plating is usually only applied to one side. It is reasonable to assume that the inventor of the invention had electroplating in mind.

<Problems with the prior art> In addition to the disadvantages of the chemical treatment described above, the above method requires the prevention of contamination of each plating solution and the need for a continuous processing line in combination with heat treatment in order to perform zinc plating subsequent to copper plating. However, it is difficult to realize it industrially due to difficulties in its structure.

<Means for solving the problem> In order to solve the above-mentioned problems of the conventional technology, it is necessary to heat the metal strip in advance, vacuum-deposit zinc on its surface, and then perform a diffusion treatment by heating. A brass plating layer is formed by this, and a brass-plated metal plate having the properties of brass and a golden tone is obtained.

<Structure of the Invention> In the present invention, copper or a copper-plated metal strip (plate) is plated with zinc by vacuum evaporation, and then
Provided is a method for manufacturing a metal strip (plate) having a brass coating layer, which comprises heating to 0.degree. C. and performing a diffusion treatment.

As the strip-shaped base material, commercially available copper strips or copper-plated steel plates (Coppertite) are advantageously used.

Theoretically, interdiffusion between zinc and copper proceeds even at room temperature, but
Since the temperature at which practical diffusion occurs, which can be applied in a continuous processing line, is about 250°C, the diffusion treatment temperature of the copper-plated metal strip after vacuum evaporation galvanizing is limited to 250°C or higher. However, if this temperature exceeds about 420°C, substantial dissolution of the deposited zinc begins to occur;
Limited to:

When vacuum-deposited zinc plating is applied to a strip of copper or copper-plated metal, if preheated to a temperature range of 250 to 450°C, the vacuum-deposited zinc will not reevaporate from the surface of the metal strip and will interdiffuse with the copper. However, a brass layer is formed on the outermost layer, but since diffusion treatment will be performed later, it is not necessary to preheat the metal strip within this temperature range, but the diffusion treatment after vacuum evaporation galvanizing can be completed in a short time. It is advantageous to preheat in the above temperature range in order to achieve this.

Preheating of the copper-plated metal strip and diffusion treatment after vacuum-deposited zinc plating can be carried out as long as the metal strip can be heated substantially in a vacuum or in a non-oxidizing atmosphere, but preferably in a gas reduction pre-treatment furnace. and a continuous vacuum evaporation galvanizing equipment equipped with a diffusion treatment furnace.

The method of the present invention is actually described in Japanese Patent Application No. 59-201423 developed by the present inventors, and in which a diffusion treatment furnace is added to a continuous vacuum evaporation apparatus having a gas reduction pretreatment furnace, which is also outlined below. It is advantageous to use an addition.

Although it is technically difficult to heat a metal strip in a vacuum, and it is easy to heat a metal strip in the atmosphere, it is possible to connect this heating furnace to a vacuum evaporation device to configure a continuous processing line. It is technically difficult to do so.

The above-mentioned continuous vacuum evaporation apparatus solved and improved this problem, and it can be said that the single-alloyed brass plating method became industrially practical for the first time with the development of this apparatus.

<Specific Disclosure of the Invention> The present invention will be specifically explained below regarding a copper-plated steel strip, but it is obvious that the present invention can be applied to copper and any copper-plated metal strip.

Figure 1 shows one of the continuous vacuum evaporation equipment used in the method of the present invention.
It is a conceptual diagram of an embodiment. This apparatus is the above-mentioned continuous vacuum evaporation apparatus with a diffusion treatment furnace added. In FIG. 1, the steel strip 1 is continuously introduced into the gas reduction annealing furnace 2 from the left inlet, where the oxides on the surface are removed and cleaned, and the steel strip 1 is annealed. 3. A first pressure application chamber for preventing atmospheric gas from flowing into the vacuum deposition system. The vacuum deposition plating chamber 5 is entered through a first seal roll chamber 4 consisting of a number of seal rolls housed in compartments each equipped with individual evacuation means for a series of stepwise evacuations and depressurization. After zinc is vacuum-deposited in step 1, it passes through the second seal roll chamber 4', which has the same purpose and configuration as described above, and which is gradually depressurized, and the second pressurization chamber 3°, which has the same purpose as described above, and then enters the diffusion treatment furnace 9. , and then cooled in the cooling chamber 10.

As shown in the figure, seal rolls may be provided on the upstream side of the first loading chamber and on the downstream side of the second loading chamber.

The structure of the seal roll chamber is described in detail in Japanese Patent Application No. 59-51149 and Japanese Patent Application No. 59-201423. The vacuum deposition chamber 5 can be configured in various ways, but the one shown here includes a zinc bath 6 heated by suitable means (electrical resistance heating means, electron beam heating means, etc.) for transporting the zinc vapor. It contains a vapor deposition means consisting of channels 7 and is equipped with rolls 8 which serve as support and inversion for the base steel strip l to be coated. This roll may be equipped with heating means.

The steel strip 1 is in a gas reduction pre-treatment furnace, for example N2 or H2
400-6 in a non-oxidizing gas atmosphere consisting of 3% balance N2
It is heated to a temperature of 00°C. A suitable heating means is a radiant tube or an electric resistance heater. In the apparatus shown in Figure 1, if the temperature on the outlet side of the gas reduction pretreatment furnace is set to 400 to 600°C, a suitable temperature of 250 to 450°C can be achieved during vacuum deposition, depending on the length of the seal roll chamber. be done. The steel strip after vapor deposition is transferred to the second seal roll chamber 4° and the second seal roll chamber 4°.
The material passes through the pressure chamber 3' and undergoes a diffusion treatment in a diffusion treatment furnace 9 having the same atmosphere as the gas reduction pretreatment furnace. After vacuum evaporation galvanizing, the temperature of the plate when it reaches the diffusion treatment furnace is 200~200℃.
Since the temperature is 400°C, heat it to a temperature of 250 to 420°C. Then, it is cooled in the cooling chamber 10 with the same atmosphere. If you take it out into the atmosphere without cooling it, the brass will oxidize and change color.

Example 1 Vacuum-deposited zinc plating was applied to the copper-plated groove strip according to the present invention using the above-mentioned apparatus. The conditions were as follows. Copper-plated steel strip dimensions: 0.5 mm thick x 30 hm wide steel strip. Copper plating thickness: ! 1lL - Threading speed:
10m/meal! Distance from n gas reduction pretreatment furnace to vacuum evaporation plating chamber:
30 m Distance gi from vacuum evaporation plating chamber to diffusion treatment furnace: 0 m Temperature of copper-plated steel sheet during zinc evaporation plating: 350°C Vacuum degree of evaporation plating chamber: 0.01 tarr Zinc evaporation plating coating amount: 20 g/m 2. Temperature of copper-plated steel sheet during diffusion treatment: 350° C. FIG. 2 is a sectional view showing the process of obtaining a brass-plated steel sheet by the above method. (a) is a sectional view of a copper-plated steel sheet. A copper plating layer 12 is present on the steel base 11. (b) shows a stage in which vacuum evaporated zinc plating is applied thereon, and a brass layer 13 is formed on the outermost layer. (C) is a cross section after the diffusion treatment, in which the entire copper plating layer has become a brass layer 13. As a result of analysis using an energy dispersive X-ray microanalyzer, this brass layer was found to be brass containing 38% Zn and 62% Cu, and had a golden yellow color on its surface.

Example 2 A brass-plated steel plate was manufactured in the same manner as in Example 1.

The conditions were as follows.

Copper-plated steel strip dimensions: 0.5mm thick x 300m
■ Thickness of copper plating on wide steel strip = 5 l ■ Threading speed: 10 m/win Distance from gas reduction pretreatment furnace to vacuum evaporation plating chamber:
30 Distance from the vacuum evaporation plating chamber to the diffusion treatment furnace: 20m2 Temperature of the copper-plated steel strip during zinc evaporation: 250℃ Vacuum degree of the evaporation plating chamber: 0.01 torr Zinc evaporation coating amount = 15g/m2 diffusion Temperature of copper-plated steel sheet during treatment: 250°C As a result of a similar analysis of a copper-plated steel sheet coated with zinc by vapor deposition under the above conditions, it was found that 28% Zn was deposited on the steel base.
A brass layer of 72% Cu was formed, and this brass layer was golden yellow.

Example 3 Brass plating was repeated under the following conditions.

Copper plated steel strip dimensions: 0.5iv thickness x 300i
Copper plating thickness of +m wide steel strip: 5 ru ■ Strip threading speed: Iom/maroin Distance from gas reduction pretreatment furnace to vacuum evaporation plating chamber gl:
30 m Distance from vacuum evaporation plating chamber to diffusion treatment furnace: 0 m Temperature of copper-plated steel φ during zinc evaporation = 420℃ Vacuum degree of evaporation plating chamber: 0.01 torr Zinc evaporation plating coating amount: 30 g/m2 Diffusion treatment Temperature of copper-plated steel sheet: 420°C As a result of analyzing the obtained brass-plated steel sheet in the same manner as above, it was found that the brass layer present on the steel base contained 46% Zn.
- It was brass with 54% Cu. This brass layer was golden yellow.

The case where brass plating is applied to one side of a steel plate that has been subjected to steel plating has been described above, but it is obvious that brass plating can be applied to both sides of a substrate whose both sides are copper plated by the method of the present invention. In addition, the material is not limited to copper-plated steel sheet.
It is also obvious that metals other than copper itself or copper-plated steel can be used.

Effects> According to the present invention, a metal plate having a brass coating layer on the surface layer can be easily manufactured without impairing the properties of the material. The method of the present invention makes it possible to easily impart the metallurgical chemical properties and aesthetic appearance of brass to the surface of a metal strip, and its industrial utility is enormous.

[Brief explanation of drawings]

FIG. 1 shows the concept of an apparatus for carrying out the method of the invention. FIG. 2 shows the structure of a brass plating layer formed by the method of the present invention.

Claims (1)

[Claims] 1. A method for producing a metal strip having a brass coating layer on the outermost layer, which comprises vacuum-evaporating zinc on a strip of copper or copper-plated metal, and then heating it to 250 to 420°C to perform a diffusion treatment.