JPH0949073A - Formation of magnesium vapor-deposited layer or zine vapor-deposited layer under controlled granular vapor-deposited substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the formation of a granular vapor-deposited substance and to prepare a sound plating layer by vapor deposition. SOLUTION: When vapor of a metal to be vapor-deposited is transferred from an evaporation tank 5 to a substrate (steel strip 13) to be subjected to vapor deposition, the flow rate of vapor passing through the outlet of a duct 12 near the substrate is regulated to <=55g/sec.m<2> in the case of Mg and <=220g/ sec.m<2> in the case of Zn. Since the flow rate of vapor at the outlet of the duct is regulated, the formation of a granular vapor-deposited substance is suppressed and a plating layer free from defects due to the granular vapor- deposited substance is formed by vapor deposition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for high-speed vapor deposition of Mg or Zn, which carries vapor through a duct.

[0002]

2. Description of the Related Art Mg-containing plated steel sheets such as Zn-Mg are
Since it shows extremely excellent corrosion resistance compared to conventional surface-treated steel sheets, future application development is expected as a structural material exposed to a severe corrosive atmosphere. The Mg taken into the plating layer is vaporized by sending Mg vapor generated in the evaporation tank to the surface of the original plating plate. When evaporating a metal such as Zn having a liquid phase in a vacuum, for example, as shown in FIG.
A device having the equipment configuration shown in is used [Nissin Technical Report No. 5
6 (1987), page 41]. In this apparatus, a source of metal to be evaporated is melted in a melting furnace 1 to prepare a melt 2. Melt 2
Is sent to the evaporation tank 5 arranged in the vacuum tank 4 via the snorkel 3. The melt 2 is heated by the heater 6 in the evaporation tank 5 and becomes vapor.

The metal vapor is guided by the hood 7 to reach an object to be vapor-deposited such as a steel plate, and is vapor-deposited on the surface of the object to be vapor-deposited. At this time, the flow rate of the metal vapor is controlled by adjusting the opening degree of the shutter 8 provided on the outlet side of the evaporation tank 5. Further, the inventors of the present invention have proposed an evaporator having a structure shown in FIG. 2 as an apparatus for evaporating Zn and Mg.
Proposed in No. 4829. In this device, the evaporation tank 5
A crucible 10 accommodating a vapor-deposited metal 9 such as Mg or Zn is placed in the chamber, and the heater 6 heats the vapor-deposited metal 9. Evaporated Mg
Alternatively, the flow rate of Zn vapor is adjusted by the shutter 8 and is deposited on the steel strip 13 from the circular duct 11 through the rectangular duct 12. In this method, most of the vapor generated in the evaporation tank 5 is vapor-deposited on the steel strip 13 which is the substrate, and the vapor that is not vaporized on the substrate and is ineffective is small. Therefore, the inside of the vacuum chamber is less contaminated and the maintenance becomes easier.

[0004]

The method of depositing the vapor transported by the duct on the substrate is a very efficient method. However, at a degree of vacuum of 1 Torr or less, if the amount of vapor passing through the duct increases, a particulate deposit of 1 μm to several mm may adhere. The thickness of the deposited layer is 0.1
Since it is often in the range of 10 μm, a deposit having a large grain size becomes a defect of the deposited film. In the case of a plated steel sheet, a deposit of several tens of μm to several mm causes defective appearance and defective press working, and cannot be shipped as a product. Also, several μm
Even when it is subjected to processing such as pressing, even the vapor-deposited product of (1) falls off to expose the base steel and deteriorate the corrosion resistance. When alloy plating is applied, the part where there is a particulate deposit is
Since the concentration is different from the other parts, the corrosion resistance is reduced by the electrochemical action. In particular, when a large amount of particulate deposit is attached, the corrosion resistance is greatly deteriorated.

[0005] The particulate vapor deposition material is complicatedly entangled with factors such as the flow direction of vapor at the outlet of the duct, the vapor cooling by the vapor deposition material, and the cooling by the atmospheric gas. Therefore, it is difficult to control the conditions, and an effective method for preventing the formation of particulate deposits has not been proposed so far. The present invention has been devised to solve such a problem, and by controlling the flow rate of vapor at the duct outlet, it is possible to effectively prevent the formation of particulate deposits and to achieve high-quality vapor deposition plating. The purpose is to form a layer.

[0006]

In order to achieve the object, the vapor deposition layer forming method of the present invention, when transporting vapor of vapor deposition metal from an evaporation tank to a vapor deposition substrate, passes through a duct outlet near the vapor deposition substrate. The flow rate of steam is 55 g / sec · m ² for Mg.
In the following, Zn is regulated to 220 g / sec · m ² or less.

[0007]

The present inventors conducted various investigations on the formation process of particulate deposits taken into the vapor deposition plating layer. As a result, it was found that the flow rate of the vapor passing through the duct outlet had a great influence on the formation of the particulate deposit. When the steam flow rate increases, the pressure inside the duct increases, and the adiabatic expansion at the duct outlet increases. Further, when the vapor flow rate increases, the pressure is locally high between the deposition target and the duct outlet, and the vapor is easily cooled by heat exchange with the deposition target even in a vacuum. As a result, the vapor temperature is lowered, and it is speculated that particulate deposits are generated.
From various experimental results, by lowering the flow rate of steam passing through the duct outlet to 55 g / sec · m ² or less for Mg and 220 g / sec · m ² or less for Zn, adiabatic expansion and cooling of steam occur. It has been found that even in the case of occurrence, the generation of particulate deposition is suppressed. The regulation of the flow rate of steam at the duct outlet is not affected by the fluctuation of the steam flow rate due to the change in the cross-sectional area in the middle of the duct, and prevents the particulate deposition material from being taken into the deposition plating layer formed on the substrate. . As a result, the obtained vapor-deposited plated layer is a high-quality plated layer without defects due to the particulate deposit. On the other hand, the flow rate of steam passing through the duct outlet is
When the Mg content exceeds 55 g / sec · m ² and the Zn content exceeds 220 g / sec · m ² , it is inevitable that the particulate deposit is taken into the vapor deposition layer obtained as described in Examples below.

[0008]

EXAMPLE Using the apparatus having the equipment configuration shown in FIG.
And Zn were evaporated. The evaporation tank 5 accommodates an iron crucible 10 having a diameter of 800 mm, and transports the generated steam to the running steel strip 13 through ducts 11 and 12 provided at the upper part. The entire apparatus is installed in a vacuum chamber, and rolls such as reels and deflector rolls for paying out and winding the steel strip 13 are arranged in the same vacuum chamber or a connected vacuum chamber. Then, illustration of rolls is omitted. The cross-sectional shape of the duct is circular until halfway, and is rectangular in the vicinity of the steel strip 13 so that steam is uniformly transported in the plate width direction. That is, at the tip of the circular duct 11 having a cross-sectional area of 502400 mm ² ,
A rectangular duct 12 of mm × 80 mm was connected.

The shutter 8 is provided at the curved portion of the circular duct 11. The flow rate of steam passing through the duct was controlled by adjusting the opening of the shutter 8 and the temperature of the crucible 10.
The duct is 65 for Mg vapor deposition to prevent vapor deposition.
It was heated to 0 ° C. and 550 ° C. for Zn vapor deposition. Nitrogen is introduced while exhausting with a pump, and the inside of the vacuum chamber is 0.0
While maintaining a reduced pressure atmosphere of 03 to 0.5 Torr, Mg and Z while changing the steam flow rate at the outlet of the duct 13
n was vapor-deposited on the steel strip 13. The surface of the obtained vapor-deposited plated steel sheet was observed by SEM, and the number of particulate vapor deposits was counted. The number was calculated as the number per unit area. The thickness of the plating layer was set so as to always be 1 μm by adjusting the feed rate of the steel sheet.

Tables 1 and 2 are tables in which the number of generated particulate deposits obtained as described above is arranged by the vapor flow rate at the outlet of the duct 13. As is clear from Table 1,
In the Mg deposition, it was confirmed that the deposition plating layer containing no particulate deposition was formed by limiting the flow rate of Mg vapor passing through the outlet of the duct 13 to 55 g / sec · m ² or less. Further, in Zn vapor deposition, as is clear from Table 2, it was confirmed that the vapor deposition plating layer containing no particulate vapor deposition was formed by regulating the flow rate of Zn vapor to 220 g / sec · m ² or less. .

[0011]

[0012]

[0013]

As described above, according to the present invention, by controlling the flow rate of vapor of vapor-deposited metal sent from the evaporation tank to the substrate through the outlet of the duct opened in the vicinity of the substrate, The formation of particulate vapor deposits is suppressed, and a sound vapor deposition layer having no defects caused by the particulate vapor deposits is formed. The steel plate etc. plated by vapor deposition in this way are
It is used in various fields by fully utilizing the high corrosion resistance of the n-plated layer or the evaporated Mg-plated layer.

[Brief description of drawings]

FIG. 1 Conventional metal vaporizer used for vapor deposition plating

FIG. 2 is an evaporator using a duct previously proposed by the present inventors.

[Explanation of symbols]

1: Melting furnace 2: Melt 3: Snorkel 4:
Vacuum tank 5: Evaporation tank 6: Heater 7: Hood 8: Shutter 9: Evaporated metal (Mg or Zn) 10: Crucible 11: Circular duct 12: Rectangular duct 13: Steel strip

Claims (2)

[Claims] 1. When transporting Mg vapor, which is a vapor deposition metal, from an evaporation tank to a vapor deposition substrate, the flow rate of Mg vapor passing through a duct outlet near the vapor deposition substrate is regulated to 55 g / sec · m ² or less. A method for forming a Mg vapor-deposited layer or a Zn vapor-deposited layer which suppresses the characteristic particulate deposit. 2. When transporting Zn vapor, which is vapor-deposited metal, from the evaporation tank to the vapor-deposited substrate, the flow rate of Zn vapor passing through the duct outlet near the vapor-deposited substrate is regulated to 220 g / sec · m ² or less. A method for forming a Mg vapor-deposited layer or a Zn vapor-deposited layer which suppresses the characteristic particulate deposit.