JPS6256566A - Manufacture of metallic strip having brass coating layer - Google Patents

Abstract

PURPOSE:To easily manufacture a metallic plate having a brass layer as the top layer without deteriorating the properties of the base metal by heating a galvanized strip-shaped metallic plate in vacuum and plating the surface of the metallic plate with copper by vacuum deposition. CONSTITUTION:A galvanized strip-shaped metallic plate having a zinc layer of >=about 1mum thickness is heated to 250-400 deg.C with electron beams in vacuum and the surface of the metallic plate is plated with copper by vacuum deposition. Thus, a fine brass coating layer is formed as the surface layer of the zinc layer on the metallic plate.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Application in Industry I> The present invention relates to a method for producing a metal strip with a brass coating 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. . In order to impart the properties of brass and the color of brass to steel and other metal materials, it is desirable to plate 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.

■) It is difficult to manufacture equipment for applying moisture to 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, 4M lead cyanide, and potassium cyanide as main components, but the equipment and costs required to prevent pollution due to the use of cyanide, which is a hazardous substance, are enormous. In addition to the disadvantages of chemical processing, in order to simultaneously electrodeposit copper, which is a negative metal, and zinc, which is a base metal, it is necessary to control the moisture content of each component, the temperature control of the electrolyte, and the pH control. There are too many conditions to be met, the tolerance range is extremely narrow, and the current density is as low as IA/dm2 or less, so it is of poor industrial utility.

JP-A No. 58-39795 discloses that the object to be plated is plated with copper and zinc separately in that order, and then the copper and zinc are diffused by heating at a predetermined temperature to form yellow '1F4 (brass) l#. A brass plating method has been proposed. Considering that this specification does not specifically describe any means for galvanizing or specifically mention vacuum thin plating, and that this type of plating is usually applied only to one side, It is highly probable that the inventor of the invention considered electroplating.

<Problems with the prior art> In addition to the disadvantages of the chemical treatment described above, this 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. It is difficult to realize it industrially due to difficulties in configuration, etc.

Means for Solving the Problem> The present inventors have been working on the development of a continuous vacuum zinc evaporation plating technology for steel strips for many years. It has been discovered that if a plated steel strap is vacuum-deposited with zinc in a preheated state, it can be plated with brass at the same time, and all of the problems of the prior art described above can be solved. Provided a new brass plating method for steel strip (
Special application 1986-).

However, from a material standpoint, it would be more advantageous in terms of productivity if copper plating could be applied to the surface using the same principle using inexpensive galvanized steel sheets that are easily available on the market. be.

<Structure of the Invention> According to the present invention, a strip-shaped galvanized metal plate is preheated in vacuum, and its surface is coated with vacuum steaming, i. Copper plating S@: A method of manufacturing a metal strip having a brass coating layer is provided.

The method of the present invention can be applied to any base metal in terms of its wood quality, and the base strip only needs to have a zinc layer of a certain thickness (one coat or more) on its surface. It may be done in any other way.

However, in practice, this method is mainly implemented using galvanized steel sheets as a material, and hereinafter, the implementation for galvanized steel sheets will be explained.

In the method of the invention, when galvanized steel strip is used as the galvanized metal strip, the heating is 250-400
It is desirable to carry out the test at 00°C.

In practice, the method according to the invention is advantageously carried out using a continuous vacuum manual copper plating apparatus having an electron beam heating system.

Phase-If diffusion of copper and zinc theoretically proceeds at room temperature, but the practical temperature at which diffusion occurs in a continuous processing line is approximately 250°C, so the temperature at which the galvanized metal strip is heated is is limited to 250°C or higher. However, if this temperature exceeds approximately 400°C, an alloy layer will begin to form between the plated zinc and the base steel, impairing the workability of the material, so the upper limit of the heating temperature is limited to this temperature. Ru.

The method of the invention is advantageously carried out using a known continuous vacuum deposition apparatus such as that described and described in Japanese Patent Application No. 59-201423; This can be carried out by an apparatus such as that described.

<Specific Disclosure of the Invention> Although the present invention will be specifically described below with respect to a galvanized steel strip, the present invention can be applied to any metal strip having a zinc coating.

FIG. 1 is a conceptual diagram of one embodiment of a vacuum evaporation apparatus used in the method of the present invention.

This device consists of a main body part 2 and coil receiving parts lO and 11. The main body is a wooden tunnel-shaped box with a structure that can withstand reduced pressure. Vacuum exhaust system 8 at the bottom
, an electron beam device 3 for heating the strip is provided, which houses a copper melting and evaporation device 6 therein.

The coil receiving boxes IO and 11 have removable front walls, can rotatably support the coil, and at least the shaft on the winding side can be driven from the outside.

In order to thread a sheet with such a device, it is sufficient to pass a wire or the like through the device in advance, load the coil into the receiving box, fix the tip of the coil to the wire, and pull out the wire.

Any known suitable vacuum evacuation system can be used.

Electron beam devices are well known, and can uniformly heat a galvanized steel sheet in the lateral direction by sweeping an electron beam from an electron gun using a deflection device or the like.

The copper melting and evaporation device 6 is designed to irradiate copper with an electron beam deflected by 90'' from an It electron gun placed horizontally in a crucible 7 whose exterior is cooled. Once the beam reaches the copper bath, a shutter 13 that can be operated from the outside of the main body is provided, preferably at a location facing the strip, and the shutter 13 is placed outside the side of the main body 2 so that the beam reaches the copper bath until the galvanized steel plate reaches a predetermined temperature. Be sure to prevent copper vapor from adhering.

To use this device, open the receiving box and, as shown,
Load the coil of raw material plated steel plate into the receiving box IO on the right side,
Fix the tip of the coil to a wire that has been passed through the device in advance, pull out the wire, fix the tip of the coil to the shaft of the left receiving box, then close the receiving box airtight, then evacuate, and remove the electron beam. Start irradiation and melt the copper, but keep the shutter of the copper melting furnace closed until the galvanized steel sheet reaches the specified temperature (250-400℃). Evaporation begins and the temperature of the galvanized steel sheet reaches the specified value. Once reached, the shutter is opened and threading begins. No special cleaning treatment is required, as normal contamination of galvanized steel sheets can be removed by amton beam irradiation.

<Example> A galvanized steel strip was vacuum-deposited copper plated according to the present invention using the above-mentioned apparatus. The conditions were as follows.

Galvanized steel strip dimensions: 0.8rsm thickness x 300
Zinc plating thickness of mm wide steel strip: 4Ai, +i Threading speed: 15m/l1in Temperature of galvanized steel strip during copper evaporation plating: 350°C Vacuum degree of base plating equipment: 0.0001 Torr Copper evaporation plating adhesion Amount: 0.2 g/m2 Figure 2 is a cross-sectional view of the brass-plated steel plate obtained above. A galvanized layer G exists on the steel base S, and a brass layer B is formed on the surface layer. As a result of analysis of this brass layer using an energy dispersive X-ray microanalyzer, this brass layer was found to contain Zn31%-C.
It was made of 69% U brass, and the surface had a golden color.

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

The conditions were as follows.

Galvanized steel strip dimensions: 0. [imm thickness x 300
Thickness of galvanized steel strip of mm width: 4gm Passing speed + 15m/l1in Temperature of galvanized steel strip during copper evaporation plating = 250°C Vacuum degree of evaporation plating equipment: 0.0001 Torr Amount of copper evaporation plating: O , Ig/m2 Similar analysis of a galvanized steel sheet coated with copper under the above conditions revealed that Zn47%-Cu5 was present on the surface of the galvanized layer on the steel base.
A 3% brass layer was formed and this brass layer was golden yellow.

Example 3 Brass plating was repeated under the following conditions.

Galvanized steel strip dimensions: 0.8 mm thick x 30 hm wide Galvanized thickness of steel strip = 4 square plate threading speed: 15+i/win Temperature of galvanized steel strip during copper vapor deposition = 400°C Vacuum degree of vapor deposition plating equipment : 0.0001 Tart Copper evaporation plating coverage: 0.3 g/m2 - As a result of similar analysis of a galvanized steel sheet coated with copper under the conditions described above, it was found that the surface layer of the galvanized layer present on the steel substrate was , Zn24%-
The surface on which a brass layer of 76% Cu was formed was golden yellow with a slight reddish tinge.

Copper is vacuum-deposited on one side of the galvanized steel sheet,
Although the case where brass plating is applied has been described, it is obvious that brass plating can be applied to both sides of a material whose both sides are galvanized by the method of the present invention. Furthermore, it is obvious that the material is not limited to galvanized steel sheets, but metal strips other than galvanized steel can also be used.

Effects> According to the present invention, a metal plate having a brass layer on the outermost 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 the drawing]

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. Patent applicant Nisshin Steel Co., Ltd.]-.

Claims (1)

[Claims] 1. A method for producing a metal strip having a brass coating layer, which comprises preheating a strip-shaped galvanized metal plate in a vacuum and applying vacuum-deposited copper plating to its surface. 2. The method according to claim 1, wherein the galvanized metal strip is a galvanized steel strip, and the heating temperature is 250 to 400°C. 3. A method according to claim 2, in which heating is performed by an electron beam method.