JPS60116787A - Method and device for plating - Google Patents

Abstract

PURPOSE:To perform two-layered single metallic plating and two-layered alloy plating with high productivity and at a low cost by subjecting the surface of a steel strip to combined plating of a vacuum deposition plating method and an electroplating method. CONSTITUTION:A steel strip 18 is heated in an oxygen free furnace 1 to remove the rolling mill lubricant sticking to the surface thereof in the stage of cold rolling by evaporation and is defatted. The strip is then heated and soaked and at the same time the surface is activated in the 1st and 2nd heating zones 2, 3. Such strip is passed through a quick cooling zone 4 and a controlled cooling zone 5 and is annealed in an overaging zone 6, by which the tensile strength, yield point, elongation, Lankford value and crystal grain size of the steel strip as a blank plate for plating are adjusted. The steel plate is introduced, in succession thereto, into a vacuum sealing device 8 via a nitrogen replacing chamber 7 and seal rolls 7. Vapor 9 of molten Zn 11 is then plated by vapor deposition on one surface of the strip 18 in a vacuum deposition device 10. Zn is likewise plated by vapor deposition on the other surface in a vacuum deposition device 10'. The steel strip is passed through a vacuum sealing device 8' and a nitrogen replacing chamber 7' and is electroplated thereon with Zn in an electrogalvanizing cell 15. The above-mentioned method is also utilizable for an alloy in place of single metal such as Zn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plating method that combines a vacuum evaporation plating method and an electroplating method, and an apparatus therefor.

As the plating method, hot-dip plating method, electroplating method, vacuum evaporation plating method, etc. are known. Below, the case where these plating methods are applied to a steel plate will be explained.

In the hot-dip plating method, after immersing the steel strip in a hot-dip plating tank,
The thickness of the plating film is controlled by spraying gas from a gas nozzle directly above the plating tank, but as the threading speed increases, it adheres to the steel strip and a large amount of molten zinc is pumped up from the plating tank. , it becomes difficult to wipe the film to the desired thickness using a gas nozzle. Especially, 509/ per side! ! 12
Even if an attempt is made to increase the sheet threading speed with the goal of achieving such a thin film thickness, the speed is only about 100 m/min or less, resulting in poor productivity and a high price per ton of plated steel sheets.

Even if the electroplating method uses recent high current densities such as 100 amperes/6 m2 or more, the current density per side is J20.
When passing a plate at a threading speed of 2001117win with the goal of a film thickness of J/m2, the number of plating baths is extremely large and the power consumption is also enormous. In addition, one side @ j) 3
If a film thickness of 097 m to 4011/rn2 is targeted, the sheet passing speed will be reduced, productivity will be poor, power consumption will be large, and the unit price per ton of plated steel sheet will be high.

Vacuum evaporation plating method is 10l/ra'~120I
/m', film thickness (on one side) of 2.00 m/min
It is possible to thread the material at a fast threading speed of ~300m/win.
It also has the advantage of having a wide range of plating film thicknesses, high productivity, and low unit price per ton of plated steel sheets, but alloy plating or double-layer plating is difficult with current technology. There is a disadvantage. -The quality of recent surface-treated steel sheets for automobiles includes alloy plating,
Or, it is becoming more advanced to double-layer plating.

As described above, the conventional hot-dip plating method and the conventional electroplating method each have advantages and disadvantages. Vacuum evaporation plating began to be industrialized, and the quality of vacuum evaporation plating of zinc was equal to or higher than that of pure zinc electroplated products. In terms of chemical conversion properties and spot weldability, pure zinc plating is becoming increasingly regarded as being slightly inferior to alloy plating, especially zinc/iron (Zn-Fe) alloy plating.

Below, further explanation will be added about the vacuum evaporation plating method of zinc on a steel strip.

The steel strip with rolling oil adhered to it after cold rolling is led to a direct-fired non-oxidizing furnace, and the steel strip is heated to about 600C to vaporize and remove the attached rolling oil, and at the same time, the steel strip is preheated. Next, the steel strip that has been work-hardened by cold rolling is introduced into a furnace called a heating zone, heated to approximately 600 to 850C, and then sequentially introduced into a quenching zone, a conditioning cooling zone, and an overaging zone for annealing, thereby producing a plated original plate. Tensile strength, yield point, required as
After adjusting the elongation, Lankford value (r), and crystal grain size, it is led to the vacuum deposition section where the degree of vacuum is approximately 1 Torr to 1 Torr.
0-4) - Vacuum deposition of zinc was performed on one or both sides of the steel strip in a vacuum chamber. However, such vacuum evaporation zinc plating is pure zinc plating, and when considering corrosion-resistant materials for automobiles, for example, it is difficult to chemically treat the plated surface before painting or spot weld to the zinc surface. , which is somewhat inferior to the recently developed alloy electroplated steel sheets.

Therefore, in order to improve chemical conversion treatment and spot weldability, the present inventors applied 5 to
We decided to compensate for the drawbacks of vacuum evaporation plating by electroplating a thin alloy plating with a thickness of approximately OA'/llI2. Plating with a thin film thickness of about 5 to 10 Jl/+a2 per side is the best of the electroplating method and does not impair productivity. / +2~1201
/ ya2 and can be plated from a thin film thickness to a thick film thickness, and the corrosion resistance is 5% dependent on the film thickness due to the sacrificial corrosion resistance of zinc.
Vacuum evaporation plating is sufficient. The present invention has the advantages of both of the above plating methods! By combining these vacuum evaporation plating methods and electroplating methods, we have developed a plating method that can provide products such as two-layer single metal plating, four-layer alloy plating, etc. at a low unit price per ton of plated steel plate. , proposes an apparatus suitable for this method.

That is, the present invention provides: (1) A plating method characterized by plating a single metal on one or both sides by a vacuum evaporation plating method, and then plating a single metal or an alloy on one or both sides by an electroplating method. .

(2) Non-oxidizing furnace for surface activation of the object to be plated, heating equipment and annealing equipment for the object to be plated, nitrogen substitution chamber, vacuum sealing device to obtain a degree of vacuum, vacuum evaporation equipment, atmospheric pressure The present invention relates to a plating apparatus which includes a vacuum sealing device for returning the object to a plating object, a nitrogen exchange chamber, an electroplating device, and an electroplating device in this order in the traveling direction of the object to be plated.

In the vacuum evaporation plating of zinc in the present invention, metal oxides on the surface of the steel strip are removed using 10 to 75% N2 in a plating pretreatment furnace, that is, a non-oxidation annealing reduction furnace, and an active material that can be used for vacuum evaporation plating is removed. In addition to adjusting the surface, various properties such as tensile strength required for plated thick plates are also adjusted. Then,
After successively increasing the degree of vacuum in a N2 atmosphere, the tube is guided into a vacuum chamber with a N2 atmosphere, and, for example, zinc is plated by vacuum evaporation, and then the pressure is returned to atmospheric pressure in a N2 atmosphere. According to the results of the pilot plant operation test, the N2 atmosphere has a dew point of approximately -
20tZ'~-70C1 oxygen amount 50 ppm~0.5
A value of 0.1 to 1.5% ppm hydrogen is good for plating.

The galvanized surface in the N2 atmosphere or the non-galvanized iron surface in the case of one side remains an active surface ◎And in the present invention, the zinc vacuum-deposited steel strip (single-sided steel) in the N2 atmosphere described above remains active. , both sides) are introduced into an electroplating tank with their active surfaces maintained without being exposed to the air, and electroplated with Zn-Fe (zinc-iron) ions, which are considered as corrosion-resistant materials for automobiles, for example. For electroplating of binary metals such as Zn-Fe, a plating film thickness of 5 to 2097 m2 per side is sufficient to satisfy only chemical conversion treatment or spot weldability, and multi-stage plating baths are required as in normal electroplating equipment. There is no need for preparation at all, and two-layer alloy plating can be performed safely. Corrosion resistance is 10~+ per side of the film thickness of the lower layer zinc vacuum evaporation plating.
209/m 2 and can be freely selected depending on the purpose.

Electroplating is Zn-Fe alloy plating, Zn-Ni alloy plating, or single-layer plating such as Zn, Fe, Ni, (Er, etc.).
Alternatively, two or more types of plating may be used.

As described above, according to the present invention, which combines vacuum deposition plating and electroplating, the following effects can be achieved.

(1) Since the active surface state is maintained in the N2 atmosphere and the material is led to the electroplating tank, the steps such as degreasing and pickling for electroplating, which were required in the past, are no longer necessary.

(2) For example, zinc plating applied by vacuum evaporation plating,
・There is no inconvenience of reacting with oxygen to form zinc oxide, and the zinc can be introduced into the electroplating tank while maintaining its pure zinc state.

(3) A plurality of electroplating tanks can be installed, thereby allowing multilayer plating.

(4) For example, Zn or a metal other than Zn is plated by vacuum evaporation plating, and then a single metal, an alloy of two or more metals, or an alloy is plated on top of this by electroplating to form a double layer. Alternatively, multilayer plating can be applied.

(5) It is possible to apply vacuum evaporation plating to only one side and electroplating the other side with a metal or alloy different from that of the evaporation plating side, or of course to plate the same metal.

(6) Corrosion resistance can be ensured by plating zinc to a desired thickness using the vacuum evaporation plating method, or by electroplating for double or multilayer plating for purposes other than corrosion resistance, such as chemical conversion treatment or spot weldability. Since the film thickness is thinner than the film thickness applied by a normal electroplating device, the electric power required for electroplating is small, and the number of plating baths is sufficient.

Next, an example of an embodiment of the apparatus of the present invention is shown in FIG.

The +8 steel strip is led to the non-oxidation furnace 1, where the rolling oil adhering to it during cold rolling is heated by a direct combustion burner, resulting in approximately 60%
It is vaporized at 0C, degreased, and preheated at the same time. Next, it is guided to the first assisting zone 2 and the second heating zone 3, and is
It is heated and soaked at 00 to 850C. The first and second heating zones are of indirect heating type, and the atmosphere of the furnace is hydrogen H.
It is a reducing atmosphere of 25% to 75%, and oxides on the surface of the steel strip 18 are reduced with hydrogen H2, and a vacuum evaporation device is used to adjust the surface to an active surface that can be plated with a certain metal, such as zinc. Ru.

Next, annealing treatment is performed in quenching zone 4, adjustment cooling zone 5, and overaging treatment zone 6 (all reducing atmospheres containing 25% to 75% hydrogen H) to obtain the tensile strength, yield point, and elongation required for the plated original plate. After adjusting the crystal grain size (to the run and couture values) and the crystal grain size, it is led to the nitrogen substitution chamber 7.

The atmosphere of nitrogen substitution M7 has a dew point of nitrogen N2 of -20C~
-70TC is a reducing atmosphere of 50 ppm to 0.5 ppm of oxygen and 0.1 to Ij% of hydrogen, and the surface texture of the original plate to which vacuum evaporation plating is applied is the same as the active surface texture obtained in overaging zone 6. Maintained. Further, the atmospheric pressure in the nitrogen substitution chamber 7 is an atmospheric pressure of 760 torr, and this pressure is maintained by providing seal rolls 17 at the front and rear. Next, vacuum seal l, tt with seal roll 17
The empty JE is evacuated, and the degree of vacuum is gradually increased from 760 torr, leading to a vacuum sealing device 8 to obtain a degree of vacuum of 1 torr to 10''-'), and then molten zinc 11 is deposited in a vacuum evaporation device 10. When heating, evaporating, and vaporizing the evaporated zinc vapor 9 onto one side of the steel strip 18, and then plating both sides of the steel strip 18, the zinc vapor 9 is guided to another vacuum evaporator i+σ to heat the molten zinc 11'. Then, the evaporated zinc vapor is applied to the surface of the other steel strip 18 by vacuum deposition plating, and the vacuum level is returned to 760 Torr (from 1 Torr to 10 Torr). Next, the nitrogen exchange chamber 1 on the outlet side is led to the electroplating tank 15 while maintaining the same atmosphere as the nitrogen exchange chamber 7 on the inlet side.In this case, the nitrogen exchange chamber 7' on the outlet side and the electroplating bath 15 are connected. Attach a hood 12 that creates the same atmosphere as the outlet nitrogen exchange chamber 1 without exposing the steel strip +8 to the atmosphere.In this case, in order to prevent the plating solution +6 from flowing back into the nitrogen exchange chamber 1, the pressure in the 7-door 12 is , out!
! Adjust the pressure to be slightly higher than that in the elementary substitution chamber 1. Reference numeral 13 represents a current-carrying roll (commonly known as a conductor μm stage), and reference numeral 14 represents an electrode for electroplating metal ions contained in the plating solution 6. Also, 1/ is seal roll teal.

In this way, plating is applied on the vacuum evaporated plating layer in an electroplating tank, and then chemical conversion treatment is performed in a chemical conversion treatment tank (not shown) in the same way as normal electroplating, and the shape is corrected with a tension repeller to obtain the °C plated steel strip 18. It is wound up.

Examples are shown below.

Example 1 According to the flow sheet shown in FIG. 1, a steel strip was plated under the following conditions. The heat treatment cycle for the steel strip was as shown in FIG. 2.

w1 Elementary substitution chamber atmospheric gas: N2 dew point knee +5sc 02a degree: 1 to 10 ppm N2a degree = 1.0% 709/vn2 vacuum degree per one side of evaporated metal dizinc: 10
-2) - Threading speed: 20sa/win Steel strip dimensions: Unannealed coil after cold rolling of plate thickness 0.6cm x width 500cm Electroplated metal: Zinc 59/cm per side 211 flow density 1t
: 4s y nhen 7/am2 plating solution: H21
304#2 Example 2 A steel strip was plated in the same manner as in Example 1 except that the following conditions were changed.

Electroplated metal dizinc 10.9/II2 per side Current density: 907 mbe 7/6m2 Plating solution: H2So4d2 As a result of Examples 1 and 2, the processing adhesion of zinc electroplated on vacuum evaporated galvanizing is as follows: , 180'', it was confirmed that no cracks or powdering occurred at the bent portion.

Example 3 A steel strip was plated in the same manner as in Example 1, except that the following conditions were changed and vacuum evaporation plating was applied to one side.

Electroplated metal dizinc/iron alloy plating (Fe/Zn ratio is 7/3) +0.9 m2 per side Current density near 07mm 7/d1112 Plating liquid: N2804pJ (2 Threading speed: 15m/win Vacuum above) One side is plated with zinc by vapor deposition, and then Zn-
As a result of a close contact bending test at 180° of a two-layer alloy plated with Fe electroplating, it was confirmed that there was no occurrence of clumping or powdering at the bent portion.

In addition, Zn can be applied to steel surfaces that have not been plated with zinc by vacuum evaporation.
The results of the 180' contact bending test of the -Fe alloy electroplated layer also confirmed that there were no cracks or powdering at the bent portion.

[Brief explanation of drawings]

FIG. 1 shows a flow sheet for applying metal plating to a steel strip according to the present invention, and FIG. 2 shows a heat treatment cycle for a steel strip in an embodiment of the present invention. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] +1) Plating characterized by plating a single metal on one or both sides by an X-vacuum deposition plating method, and then plating a single metal or an alloy on one or both sides by an electroplating method. Method. (2) Non-oxidizing furnace for surface activation of the object to be plated, soaking equipment and annealing equipment for the object to be plated, nitrogen substitution chamber, vacuum sealing device to obtain a degree of vacuum, vacuum evaporation equipment, return to atmospheric pressure A plating device comprising a vacuum sealing device, a nitrogen purge chamber, and an electroplating device installed in this order in the traveling direction of the object to be plated.