KR20140032521A - Method for decreasing metal-gas in snout and the snout thereof - Google Patents

Abstract

According to one aspect of the present invention, a method for reducing metal gas from a snout in a molten metal plating process comprises: a step of cooling a plated material to generate the condensation nuclei of the metal gas on the surface of the plated material; and a step of putting the plated material on which metal condensate formed when the metal gas is condensed around the generated condensation nuclei is attached into molten metal. The diameter of the formed metal condensate is less than 1μm (Except 0) at the time when the plated material starts entering into the molten metal. According to the other aspect of the present invention, the snout in the molten metal plating process comprises a cooling device for cooling the surface of the plated material. [Reference numerals] (AA,BB) Steel sheet to be plated

Description

METHOD FOR DECREASING METAL-GAS IN SNOUT AND THE SNOUT THEREOF}

The present invention relates to a method for treating metal vapor inevitably generated in a molten metal plating process, and more particularly, to a method for reducing metal vapor generated on a molten metal surface inside a snout in a molten metal plating process of a steel sheet and a metal. It is about the snout which can reduce steam.

In general, the metal plated steel sheet has a wide range of applications from general building materials to home appliances and automotive exterior plates requiring beautiful surface management based on excellent corrosion resistance. The method of manufacturing such a metal plated steel sheet generally uses a method of plating with molten metal, but the sensimilar method is the mainstream.

Figure 1 is a schematic diagram showing a typical molten metal plating line according to the senseim method. In the following, the molten metal plating line according to the sensmere mirror method will be described with reference to FIG. 1.

First, the cold-rolled plated material (steel plate) is continuously plated through a payoff reel (not shown) and a welding machine (not shown). Thereafter, in order to remove the residual stress applied to the steel sheet, the annealing treatment is performed at a temperature of 400 to 900 ° in the heating furnace 110 filled with an inert gas for maintaining a reducing atmosphere. Thereafter, in a state where a temperature suitable for the plating operation is maintained, the molten metal is charged into the molten metal in the plating bath 130 filled with molten metal.

At this time, the snout 120 is provided between the heating furnace and the plating bath. These snouts are installed to directly connect the ends of the furnace with the plating bath filled with molten metal. The snout serves to induce the entry of the plated material (steel sheet) into the molten metal. In addition, by blocking the air from the outside to prevent the surface oxidation caused by the heat-treated plated material exposed to the atmosphere, it serves to maintain the state that the plated material can be plated. In addition, since the upper part of the snout is connected to the heating furnace and the lower part is connected to the hot molten metal, an inert gas is introduced around the metal melt inside the snout to prevent defective plating from the inside of the heating furnace, thereby reducing the atmosphere. Is formulated.

The steel plate plated while passing through the heating furnace 110, the snout 120, and the molten metal plating bath 130 in sequence by air injected from the air knife 140 provided on the plating bath 130 The amount of plating is adjusted to have a desired plating thickness. Subsequently, the steel sheet wiped so as to have a uniform plating thickness is subjected to a temper rolling mill, cut through a cutter through proper surface roughness provision and shape correction, and then wound in a tension reel to be produced as a final plating coil product.

On the other hand, in the step of entering the steel plate of the heating furnace 110 into the plating bath 130 through the interior of the snout 120, because of the reducing atmosphere formed in the interior of the snout 120, Pure metal vapor is evaporated from the molten metal surface of the naut 120. At this time, the evaporated metal vapor is condensed to form an ash, and the metal condensate A is inevitably generated.

In particular, the metal condensate (A) condensed in the snout 130 is attached to the inner wall of the snout 130 when the size of the condensate (A) is larger than the threshold level, floating in the snout and eventually plated It adheres to the steel sheet or falls to the molten metal surface to cause a surface defect of the plated material. That is, it is the defect caused by the metal condensate that has the greatest influence on the surface quality of the plated steel sheet of molten metal.

On the other hand, in order to prevent surface defects caused by metal condensate, which is a critical defect factor on the surface quality of such a molten metal plating material, various techniques are known. This can be divided into five categories.

First, a method of suppressing the evaporation of the molten metal itself, Patent Documents 1 to 3 are disclosed. Second, a method of preventing the vaporized metal vapor particles from condensing with each other, Patent Documents 4 and 5 are disclosed. Third, a method of removing the metal vapor condensate that falls back into the molten metal and causes a defect in the plating bath process, and Patent Document 6 discloses this. Fourth, Patent Document 7 discloses a method of preventing mixing and deposition with a plated material.

Finally, as the most practical solution, as a method of reducing or removing inevitably generated metal vapor, the present invention corresponds to the description thereof. Existing known techniques related to this technique include Patent Documents 8 and 9.

Patent document 8 has provided the metal steam suction duct, a cooler, and the circulation duct which returns steam inside a snout. However, the present technology has a problem in that as the condensation of the metal vapor proceeds, due to the characteristics of the porous metal vapor condensate, the cold air transfer of the cooler is insufficient and condensation is no longer possible. There is also a disadvantage that the condensate can easily re-scatter. In addition, since the suction duct, the cooler and the circulation duct must be separately configured and operated, there are also disadvantages in that additional costs are not applied to the industry.

Patent document 9 is a system for sucking foreign substances adhering to the surface of a steel sheet, and monitoring the oxygen concentration of suction and discharge pipes to improve the operating stability of the system, and monitoring the differential pressure of the suction pipes before and after the foreign matter collecting filter to automatically detect the foreign matter collecting path. The present invention relates to a system capable of changing and thus performing a foreign material removal operation without stopping the operation. In this technology, a collection filter is disclosed by a method of removing foreign matter. However, the size of the metal vapor particles is about 1-10 nm, even if grown as a condensate is only a few tens to hundreds of nm in size. Therefore, collection is impossible when using a general industrial filter such as a nonwoven fabric. In addition, even if expensive glass fiber filters are used, it is difficult to completely collect them, and there is a disadvantage in that they are almost impossible to apply industrially due to low collection rate.

As mentioned above, although the method of removing the inevitably evaporated metal vapor is a key method for solving the problem of the metal vapor which causes the surface quality deterioration, it is rather difficult to apply the research results industrially. there was. Thus, it remains an area of ongoing research.

Japanese Patent Publication No. 1995-062512 Korean Patent Publication No. 1986-0001211 Korean Patent Publication No. 2001-0028283 Japanese Patent Publication No. 2003-027200 Japanese Patent Publication No. 2002-275606 Japanese Patent Publication No. 1995-180014 Japanese Patent Publication No. 1997-095761 Japanese Patent Laid-Open No. 1994-306555 Korean Patent Publication No. 2006-0072702

One aspect of the present invention is to provide a reduction method that can effectively reduce the metal vapor inside the snout causing the deterioration of the surface of the plated steel sheet in the molten metal plating process, without additional expensive equipment.

Another aspect of the present invention is to provide a snout that can easily implement the above reduction method.

In one embodiment of the present invention, a method for reducing metal steam in a snout of a molten metal plating process includes: cooling a plated material such that condensation nuclei of the metal vapor are generated on the surface of the plated material, and metal around the generated condensation nucleus. The metal condensate formed by the condensation of the vapor to enter the metal material is attached to the molten metal, wherein the formed metal condensate has a diameter of less than 1μm (excluding 0) at the time of entry of the metal molten metal It may include a method for reducing metal vapor in the nut.

In addition, another aspect of the present invention, the snout of the molten metal plating process may include a cooling device capable of cooling the surface of the plated material.

According to an aspect of the present invention, the metal vapor inevitably generated inside the snout of the molten metal plating process can be easily reduced without additional expensive equipment or work process. Therefore, work efficiency increases, the surface defect of a to-be-plated material can be suppressed, and the quality of a plated steel plate can be improved.

Figure 1 is a schematic diagram showing a plating process according to the sensimere method, which is a general molten metal plating process method.

The present inventors have studied in depth the method for improving the surface quality deterioration phenomenon of the plating material by the metal vapor generated in the molten metal inside the snout of the molten metal plating process. As a result, when the generated metal vapor is condensed to nano size (diameter size less than 1 μm) and adheres to the surface of the plated material, and enters the molten metal of the plating bath, the metal vapor is effectively reduced without additional equipment for removing steam. It has been recognized that the present invention can be achieved.

Hereinafter, a method for reducing metal steam in a snout constituting an aspect of the present invention, which is conceived in consideration of the above-described essential points of the present invention, will be described in detail.

According to the method of reducing the metal vapor in the snout disclosed in one aspect of the present invention, in order to effectively reduce the metal vapor generated in the molten metal plating process, by controlling the surface temperature of the plated material, the metal vapor particles surface the plated material Disclosed is a method for treating metal vapor by generating a condensation nucleus at condensation and adhesion, and entering the plating material having the metal condensate into the molten metal.

The condensation of steam occurs when the steam is cooled at a constant pressure to lower the temperature below a certain temperature or when the steam is pressurized to cause the steam pressure to exceed the saturated steam pressure. At this time, in the process of condensing the gaseous metal vapor into the metal in the solid state, a process of generating a condensation nucleus is necessary. Therefore, in one aspect of the present invention, at a predetermined position inside the snout, the temperature of the metal vapor is lowered to induce condensation nuclei to be generated.

That is, according to the method of reducing the metal steam in the snout disclosed in one aspect of the present invention, first, the temperature at a predetermined position is controlled so that the condensation nuclei of the metal vapor are generated on the surface of the predetermined position. At this time, it is preferable that the predetermined position where generation of the condensation nucleus occurs is the surface of the plated material.

As a predetermined position where the heterogeneous nucleation can occur, an inner wall surface of the snout, an optional wall surface additionally formed, or the surface of the plated material can be considered. The inner wall surface of the snout is nucleated to form metal grains and condensate easily, but there is an aspect that is not effective for continuously removing or treating the condensate. In addition, if additional wall surfaces are additionally added, a process of providing an arbitrary wall surface inside the snout is further required, and further problems may occur. There is also a need for a facility that can continuously remove or process the resulting condensate.

On the other hand, the surface of the plated material is easily capable of non-uniform nucleation, and continuously deposited in the molten metal in the plating process, thereby effectively removing the metal vapor condensate without additional equipment. Further, even if the material to be plated does not escape on the surface before entering the molten metal, no problem arises if the size of the condensate can be controlled to such an extent that it does not cause surface defects. Therefore, the surface of the plated material is preferable as a predetermined position for inducing the generation of the condensation nucleus.

At this time, in the process of controlling the temperature of the surface of the plated material to generate the metal vapor condensation nucleus, there may be a method such as heating, cooling. However, in consideration of the annealing process of the previous step, the temperature is controlled through a cooling process, but it is not necessarily limited thereto.

At this time, the generation of the condensation nuclei is preferably produced by heterogeneous nucleation, not uniform nucleation. This is because, in the case of heterogeneous nucleation, the amount of interfacial energy required for generation of condensation nuclei becomes much smaller than in the case of homogeneous nucleation, and the subcooling required for nucleation is also reduced by the theory of metal phase transformation.

At this time, the diameter of the final metal vapor condensate in which the condensation nucleus is generated and grown is preferably less than 1 μm (excluding 0) based on the moment when the plated material enters the molten metal. This is because, if the size of the condensate of the metal vapor adhered to the plated material is 1 μm or more, the plating may substantially cause defects on the surface of the plated material. That is, in the size of nano size, even if the condensate grows and is plated on the surface of the plated material or is ablated to the surface of the molten metal, it is not a cause of definite surface defects. The condition is to be kept well. In addition, the diameter of the condensate is more preferably 600nm or less (excluding 0). For the same reason as above, the possibility of occurrence of surface defects almost disappears at 600 nm or less. As for the size of the said condensate, 50 nm or more and 600 nm or less are more preferable. This is because if the size of the condensate is less than 50 nm, the amount of vapor to be condensed is very small, it is difficult to implement the effect of the intended metal vapor removal in one aspect of the present invention.

At this time, it is preferable that the supercooling degree of the metal vapor at the moment when the condensation nucleus is formed on the surface of the plated material is 2 to 30%. The subcooling degree of the metal vapor is more preferably 5 to 10%. In addition, in order to implement the preferred supercooling of the metal vapor, a cooling process for lowering the temperature of the plated material is essential. The means for cooling the plated material for forming the supercooling degree of the metal vapor is not particularly limited as long as it can reduce the surface temperature of the plated material to a desired degree. However, it is preferable to use a device such as a gas spray, a refrigerant spray, a cooling roll, or the like. desirable.

The degree of subcooling is a key factor for implementing one aspect of the present invention, which influences the generation of the metal vapor condensation nucleus. When a certain critical supercooling degree is reached, the size of the condensation nuclei to be formed exceeds the size of the critical nuclei that can form the condensation nuclei, and the number of generation of the condensation nuclei is rapidly increased. However, if the subcooling is below this critical subcooling, no condensation nuclei are formed and crystal growth does not occur. At this time, the heterogeneous nucleation is preferable because the value of the critical supercooling is smaller than that of the uniform nucleation.

In general phase transformation theory, super cooling refers to a case in which a liquid or solid solution can be maintained by inertia even when the melt or solid solution is cooled below the solidification temperature or the solubility line. When the degree of subcooling reaches a certain limit, coagulation or precipitation occurs. The degree of subcooling is expressed as follows.

Subcool (° K) = Saturated Steam Pressure Temperature-System Steam Temperature

(Unit: absolute temperature)

In this case, the system refers to a region of interest, that is, a region in which steam of interest is present. Under the present invention, the steam temperature of the system in the formula of the subcooling means the steam temperature at the surface of the plated steel sheet in which the vapor phase to be removed forms a condensation nucleus.

On the other hand, at a given temperature, the saturated steam pressure depends on the type of metal vapor, and in particular in the case of heterogeneous nucleation depends on the shape of the wall surface of the condensate. Therefore, the critical subcooling required for nucleation is influenced by the above conditions and becomes inconsistent, making it difficult to determine the degree of critical subcooling.

Therefore, it is necessary to make the unit dimensionless and to re-define the degree of subcooling to a value which does not change depending on the substance. Therefore, in the present invention, the degree of subcooling is redefined as follows. The redefined subcooled temperature of the steam under a given temperature, expressed as absolute temperature, is given by

Subcooling (%) = (Saturated Steam Pressure Temperature-System Temperature) / Saturated Steam Pressure Temperature * 100

The supercooling of the metal vapor according to the redefinition on the surface of the plated material It is preferable to control to 2-30%. If the subcooling degree according to the above definition is less than 2%, the generation of condensation nuclei of the metal vapor does not easily occur on the surface of the plated material, and thus the metal vapor is not condensed, so that the purpose of effective metal vapor reduction cannot be achieved. In addition, when the subcooling exceeds 30%, on the surface of the plated material, nucleation is performed and metal condensate grows rapidly, and the final diameter of the grown condensate is in the range disclosed in the present invention (less than 1 μm). May not be able to enter. In this case, if the resulting condensate falls into the molten metal, there is a problem that may cause surface defects.

At this time, the entry speed of the metal to the molten metal is preferably 0.2m / s or more in order to implement the effect intended by the present invention. The upper limit is not particularly limited as long as the plated material enters the molten metal and can be smoothly plated.

At this time, the degree of supercooling on the surface of the plated material is more preferably controlled differently depending on the speed of entry of the plated material into the molten metal. That is, the supercooling is 2 to 30% when the plated material enters the molten metal in the snout, when the inflow speed of the plated material is 0.2m / s or more and less than 1m / s, and the speed is 1m / s ~. 3 to 30% for 2m / s, 5 ~ 30% is more preferable when the entry speed exceeds 3m / s.

The reason for controlling the lower limit of the supercooling degree differently according to the entry speed of the plated material is that the time for the plated material to stay inside the snout depends on the entry speed. If the inflow rate of the plated material is too slow, less than 0.2 m / s, the exposure time of the plated material to the metal vapor becomes too long, resulting in coarsening of the condensate. In addition, when the penetration rate of the plated material is more than 0.2m / s ~ less than 1m / s, there is sufficient room for heterogeneous nucleation and the growth of metal condensate on the surface of the plated material. Therefore, the lower limit of the degree of subcooling is preferably 2%. In addition, when the ingress speed of the plated material is 1m / s ~ 2m / s, a considerable degree of subcooling is required and at least 3% or more. In addition, when the entry speed of the plated material exceeds 3m / s, which is very fast, high subcooling degree is required, and at least 5% is required.

On the other hand, the upper limit of the degree of subcooling is equally controlled to 30%, because if the value of subcooling is very large, the influence of the time for the plated material to stay inside the snout is small. That is, when the degree of subcooling is 30% on the surface of the plated material, a sufficient degree of heterogeneous nucleation and metal condensation may be formed on the surface of the plated material, regardless of the time of staying inside the snout. Therefore, in the case of overcooling exceeding 30%, the energy efficiency decreases during the cooling of the plated material.

According to a method for reducing metal steam in a snout, which is an aspect of the present invention, a plated material having a metal condensate attached thereto is then introduced into the molten metal as described above. In this process, the metal condensate particles on the surface of the plated material having an appropriate size which does not cause surface defects as described above are ablated and dropped back into the metal melt, or covered with the plating liquid in the metal melt while attached to the plated material. do. Thereby, the effect of reducing the metal vapor in the snout which is an object of the present invention is achieved.

In the following, the snout for reducing metal vapor in the interior of another aspect of the present invention will be described in detail.

In another aspect of the present invention, a snout for reducing internal metal vapor is provided with a cooling device capable of cooling the surface of a plated material so that the above-described method for reducing metal vapor in the snout can be easily implemented. It includes. At this time, the cooling device of the plated material is not particularly limited as long as it is a device capable of lowering the surface temperature of the plated material to a desired degree, it is preferable that the cooling means such as gas injection, refrigerant injection, the cooling roll is provided.

At this time, it is preferable that the cooling device can control the surface temperature of the plated material, so that the supercooling degree of the metal vapor on the surface of the plated material can be controlled within the range disclosed by the present invention.

Moreover, it is preferable that the said snout includes the heating apparatus which can heat the snout inner wall. Inside the snout, the location where the condensation nuclei of the metal vapor are generated may be the inner wall surface of the snout in addition to the surface of the plated material, as described above. As intention of the present invention, in order to cause the generation of condensation nuclei of the metal vapor only on the surface of the plated material, it is preferable to raise the temperature of the snout inner wall. Thus, in one aspect of the invention includes a heating apparatus capable of heating the snout inner wall.

At this time, the heating device is not particularly limited as long as the device can raise the surface temperature of the snout to the desired degree in the present invention.

At this time, it is preferable that the inner wall temperature of the snout heated by the said heating apparatus is 400-550 degreeC. This is because at temperatures below 400 ° C., the condensation nuclei can also form on the surface of the snout inner wall. In addition, since the condensation nuclei cannot be generated due to an increase in the inner wall temperature at a temperature above 550 ° C., even though the effect is saturated, the temperature rises further, thereby reducing the efficiency in terms of thermal efficiency and cost.

In the following, embodiments of the present invention will be described in detail. The following examples are for the understanding of the present invention, and the present invention is not limited thereto.

( Example )

The present inventors carried out ICP, XRD and EDS analysis by collecting metal vapor generated from the snout, and performed three-dimensional shape analysis, SEM observation and analysis by taking surface defect samples. As a result, the size of the metal vapor is known to be from 1 to 10 nanometers in diameter, and when they condense, very porous pores condensate, resulting in very low specific gravity of less than 1, which disperses well in gas flow. Blowing was observed.

In addition, the present inventors carried out an experiment on the metal vapor reduction method, which is an aspect of the present invention using a hot-dip plating simulator. The molten metal was prepared by maintaining zinc at a melting point of 460 ° C. or higher, and the plated material was prepared by cleanly cleaning the surface with ordinary carbon steel.

In the environment of this experiment, the mechanical operation of repeatedly removing the surface of the oxide film with a skimmer was performed to induce continuous evaporation of the molten metal. This created an environment in which zinc metal vapor is continuously generated. In the actual plating process, the plated material continuously enters the molten metal and serves as a skimmer to remove the oxide film formed. In addition, in the same manner as the internal environment of the snout, the inside of the experimental chamber was formed in a vacuum, and then prepared by filling a gas that forms a reducing atmosphere of 10% H ₂ -N ₂ .

The process of performing the experiment is as follows. First, a molten metal and a gas supply device were prepared. Next, the quartz tube serving as the melt and annealing furnace was evacuated to evacuate air and oxygen. The steel plate was annealed on a clean sample of the steel sheet and suspended in a quartz tube filled with 10% H ₂ -N ₂ gas to form a reducing atmosphere. Thereafter, the liquid was cooled with N ₂ gas, which is an inert gas, immediately before entering the molten metal. At this time, by varying the flow rate of the cooling gas to bring ΔT to vary, the supercooling value corresponding to the conditions was changed.

On the other hand, the steel plate samples were suspended at a right angle on the molten metal, and experimented while changing the time exposed to the metal vapor. This is a variable setting corresponding to the entry speed in the snout. Therefore, the exposure time set for each of the above experimental examples was converted into the entry speed of the plated material on the simulation system, and the values thereof are shown in Table 1 below.

Thereafter, a steel sheet sample was deposited with the molten metal to perform plating. In this process, the condensate produced on the surface of the plated object was observed, and the surface quality was actually evaluated by plating on it. The results are shown in Table 1 below.

division Molten Temperature (˚K) Surface Temperature of Plated Material
(˚K) Subcooling
(Temperature difference)
(˚K) move
speed
(m / s) Subcool
(%) Condensate
Distribution Condensate
Size (nm) surface
quality Comparative Example 1 733 723 10 2 One X ◎ X Inventory 1 733 713 20 2 3 ○ ◎ △ Inventory 2 733 633 70 2 10 ◎ ◎ ○ Inventory 3 733 583 150 2 20 ◎ ○ ○ Honorable 4 733 513 220 2 30 ◎ ○ △ Comparative Example 2 733 473 260 2 35 ◎ X X Inventory 5 733 633 70 3.5 10 ○ ◎ ○ Inventory 6 733 633 70 3.0 10 ○ ◎ ○ Honorable 7 733 633 70 0.5 10 ◎ ○ ○ Comparative Example 3 733 633 70 0.1 10 ◎ X X

* Subcooled temperature (△ T / T) (%) as redefined in this experiment:

(Temperature of current steam pressure-temperature of saturated steam pressure) / T, (T: absolute temperature)

With respect to the effect of the present invention according to the experimental results, the distribution and size of the condensate, the surface quality was observed and evaluated in the following criteria.

(Distribution of condensate)

◎: Condensate evenly and densely distributed over the entire sample

○: Condensate is generally uniform but loosely distributed throughout the sample

X: The condensate is non-uniform, coarse and very small in absolute volume over the entire sample

(Size of condensate)

◎: The size of the condensate is observed from about 1 to about 600 nm

○: the size of the condensate was observed from about 600 to about 999 nm

X: The size of condensate is observed above 1μm

(Surface quality)

○: No surface defects due to condensation in the plating layer

△: Surface defect caused by condensate is seen on the plating layer, but can be treated in the next process

X: Defect in the plating due to surface defects caused by condensate.

As a result of the above experiment, in the case of the invention example to which the supercooling degree satisfying the control range of the present invention was confirmed, the formation of condensate having a diameter of less than 1 μm was confirmed. In particular, it was confirmed that surface defects after plating did not occur when the diameter of the condensate was 600 nm or less.

In the following, the respective examples are divided and examined in detail.

In the case of Comparative Example 1, the subcooling value is 1%, which is smaller than the range controlled by the present invention. It could be confirmed that the condensation core was not formed sufficiently, so that the distribution of the condensate was poorly formed. In this case, it was confirmed that the surface quality of the plated steel sheet was degraded by causing surface defects of the metal vapor condensate.

In the case of Comparative Example 2, the subcooling value is 35%, which is a value beyond the range controlled by the present invention. It can be seen that the condensation nuclei are rapidly formed and the metal vapor condensate is rapidly coarsened. Also in this case, it was confirmed that the surface quality of the plated steel sheet was degraded due to the metal vapor condensate on the surface of the coarsened plated material.

Therefore, based on Comparative Examples 1 and 2 and Inventive Examples 1 to 4, it was confirmed that there is critical significance in the preferred subcooling control range of 2 to 30% disclosed in the present invention.

In Comparative Example 3, the moving speed of the plated material exhibits a value of 0.1 m / s outside the control range of the present invention. That is, as the holding time of the material to be plated in the snout becomes too long, it means that the metal vapor is exposed too long. Accordingly, it was confirmed that the condensates were evenly and densely distributed, but their size was too coarse, and surface defects also occurred.

As a result of the comprehensive experiment, it was confirmed that the greater the degree of subcooling, the longer the residence time at the top of the melt, the larger the size of the metal condensate. In addition, the metal vapor generated in the snout disclosed in one aspect of the present invention is condensed on the surface of the plated material and deposited in the molten metal, it is possible to confirm the effect of reducing the surface defects of the metal vapor in the snout there was.

110: heating furnace
120: snout
130: molten metal plating bath
140: air knife

Claims (7)

In the method of reducing the metal steam inside the snout of the molten metal plating process,
Controlling the surface temperature of the plated material such that condensation nuclei of the metal vapor are generated on the surface of the plated material;
And a metal plating material attached to the metal condensate formed by condensation of metal vapor around the generated condensation nucleus into the molten metal,
The formed metal condensate has a diameter less than 1μm (excluding 0) at the time of entry of the molten metal of the metal to be plated metal steam reduction method.
The method according to claim 1,
The metal condensate is a method of reducing metal vapor in the snout having a diameter of 600nm or less (excluding 0) at the time of entering the molten metal of the plated material.
The method according to claim 1,
On the surface of the plated material, the supercooling degree of the metal vapor generating the condensation nucleus is 2 to 30% in the snout metal vapor reduction method.
The method of claim 3,
The supercooling degree is 2% to 30% when the ingress speed of the plated material is more than 0.2m / s ~ 1m / s, 3 ~ 30% when 1m / s ~ 2m / s, 5 ~ 30 when the 3m / s or more Method for reducing metal vapor in snout%.
In the snout of the molten metal plating process,
A snout for reducing metal vapor comprising a cooling device capable of cooling the surface of the plated material.
The method according to claim 5,
The snout is a snout for metal vapor reduction comprising a heating device capable of heating the inner wall of the snout.
The method of claim 6,
The inner wall temperature of the snout heated by the heating device is 400 ~ 550 ℃ snout for reducing metal vapor.

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