KR101194459B1 - Coating method of surface coating composition for molten zinc bath member, and coating member - Google Patents

Abstract

The present invention provides 40-50% by weight of WC, 20-30% by weight of Cr, 10-20% by weight of Ni, 8-15% by weight of Co, 0.1-5% by weight of Si and 0.1-5% by weight of B It provides a coating composition for a hot dip galvanized bath member. The molten zinc bath member coated according to the present invention not only has excellent abrasion resistance, zinc corrosion resistance and heat resistance, but the composition is also capable of ultra-fast spraying and thus is simply coated on the molten zinc bath member. In addition, since the coating is possible at room temperature, there is an effect of coating without thermal deformation of the member.

Description

Coating method and coating member of coating composition for hot dip galvanized bath member {COATING METHOD OF SURFACE COATING COMPOSITION FOR MOLTEN ZINC BATH MEMBER, AND COATING MEMBER}

The present invention relates to a coating method and a coating member of a coating composition for a hot dip galvanizing bath member.

In general, steel sheets used in computer bodies and automobiles are used by galvanizing through a galvanizing process.

This is because, when the first steel sheet produced in steel mills is directly exposed to the atmosphere, oxidation proceeds rapidly, and the lifespan thereof may be shortened or the aesthetics due to corrosion may be reduced.

Therefore, steel sheets used in various industrial sites are mainly galvanized, except in special cases, so that they are not easily oxidized and corroded even when exposed to the air.

In order to galvanize the steel sheet, the most commonly used method is to continuously immerse the steel sheet in a zinc bath in which molten zinc is dissolved and then take it out again. In a steel mill, a steel sheet is usually manufactured in a roll form and supplied. The galvanizing roll (for example, SINK roll) for inducing continuous transfer of the steel sheet is installed.

Referring to Figure 1, the galvanized roll 10 is formed of a spherical roll body 11, is installed in the zinc melting furnace (2) to enable free rotation, this installation and rotation is mainly suspended on the ceiling It is hold | maintained by a pair of fixed mounting table 20 etc. That is, in the state where the pair of fixed mounting brackets 20 are suspended from the ceiling of the workplace where the zinc melting furnace 2 is installed, the zinc plating rolls 10 are rotatably installed between the fixed mounting brackets. It is to serve to continuously transfer the steel sheet (1) that is immersed in) and taken out again.

At this time, in order to install the galvanized roll 10, a fixed hole 20 is provided so that the shaft of the galvanized roll 10 can be inserted into the fixed hole 20, but only the hole for the fixed hole 20 is installed. When used in the drill hole is used in combination with the rotating hole in the relationship that can significantly shorten the life of the fixed mounting 20 or the shaft.

The hot dip galvanized roll has a problem that the hot dip galvanized roll is deteriorated due to the corrosion by the reaction with the hot dip and adhesion of intermetallic compounds and the deteriorated component adversely affects the quality of the galvanized steel sheet as a product.

In order to solve this problem, in Patent Document 1, the surface of the roll is thermally sprayed with a carbide containing 85 wt% or more of WC, and then a ceramic film containing at least one of nitride, carbonitride, Ti, Al, Hf, or Zr. It is proposed a ceramic-coating roll for a molten zinc bath, which is surface coated.

In addition, Patent Document 2 is a powder, or two or more alloys selected from Ta, Ti, V, Mo, Cr, Zr, Nb, Hf, or W, which is a high melting-point metal powder having a melting point higher than Co. A surface coating material for the immersion member of a molten metal galvanized bath, in which 50 to 90% by weight of ceramic powder containing at least one of an oxide, nitride, carbide, boride, or silicide is dispersed in a powder.

In addition, Patent Document 3 is a surface coating material for forming a coating layer on the surface of the molten zinc bath member, the surface coating material comprises WC powder particles and a binder metal, and the binder metal is electrochemically more precious than Co and Co A surface coating is disclosed which consists of an alloy structure containing a (nobler) metal element and having a single phase.

The surface of the rolls limited in the above-mentioned Patent Documents 1, 2 and 3, generally referred to as sink rolls, are made of tungsten carbide (hereinafter referred to as "WC") and Co (hereinafter referred to as "WC /") to improve zinc corrosion resistance while maintaining wear resistance. Heat treatment using a cermet comprising a " Co cermet "). However, zinc corrosion resistance is not sufficient, and deterioration of the roll surface may cause product defects.

In addition, Patent Document 1 has a problem in that the cost and processing time increases to perform two types of thermal spraying, Patent Document 2 has a problem that the thermal spraying process conditions are limited in order to melt and disperse high melting point metal Have In addition, Patent Document 3 has a disadvantage in that a relatively large amount of WC is used, the bonding strength with the coating member is decreased, and the heat resistance is poor.

Patent Document 1: Japanese Patent Laid-Open No. 9-25583

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-331995

Patent Document 3: Korean Patent Publication No. 2010-0016273

Accordingly, in the present invention, the amount of WC satisfying the required wear resistance is selected, and the coating composition is designed with a component that satisfies the corrosion resistance and heat resistance thereto, and then a small amount of boron (B) is used to enable bonding and ultra-fast spraying. The above-mentioned problem was solved by the addition, and the present invention was completed based on this.

Accordingly, it is an object of the present invention to provide a surface coating composition for a molten zinc bath member having excellent wear resistance, zinc corrosion resistance and heat resistance.

Another object of the present invention is to provide a method for coating the coating composition on a molten zinc bath member easily and without deformation of the member.

Another object of the present invention is to provide a molten zinc bath member coated by the above method.

Surface coating composition for a molten zinc bath member of the present invention for achieving the above object is 40 to 50% by weight of WC, 20 to 30% by weight of Cr, 10 to 20% by weight of Ni, 8 to 15% by weight of Co, It consists of 0.1-5 weight% Si and 0.1-5 weight% B.

In a preferred embodiment of the present invention, the particle size of the coating composition is characterized in that 40 ~ 100㎛.

Coating method of the coating composition for a hot dip galvanized bath member to achieve another object of the present invention is 40 to 50% by weight of WC, 20 to 30% by weight of Cr, 10 to 20% by weight of Ni, 8 to 15% by weight Providing a mixed powder consisting of Co, 0.1 to 5% by weight of Si and 0.1 to 5% by weight of B; Melting the mixed powder, and then pulverizing to a particle size of 40˜100 μm; And spraying the pulverized product at a high speed of Mach 3 to 5 to coat the hot dip galvanized bath member in a semi-molten state.

A hot dip zinc bath member for achieving another object of the present invention is coated with a thickness of 0.2 ~ 0.5 mm on the surface of the hot dip zinc bath member by the coating method of the coating composition for the hot dip galvanized bath member.

In a preferred embodiment of the present invention, the tub member is characterized in that the shaft, the fixed mount, the bearing, the rotating hole formed in the fixed mount, the stopper or a combination thereof.

As described above, the molten zinc bath member coated with the surface coating composition for the molten zinc bath member according to the present invention not only has excellent wear resistance, zinc corrosion resistance and heat resistance, but the coating composition is capable of ultra-fast spraying and thus It is coated easily. In addition, since the coating is possible at room temperature, there is an effect of coating without thermal deformation of the member.

Therefore, it is a very useful invention such that the productivity and economics of the continuous hot dip plating process for continuous zinc plating the steel sheet can be improved at the same time.

1 is a schematic view showing a process of continuous galvanizing a steel sheet in roll form.

Hereinafter, the present invention will be described in more detail.

1 is a schematic view showing a process of continuous zinc plating a roll-shaped steel sheet, schematically showing a process in which the steel sheet is continuously plated by using a galvanizing roll installed in the zinc melting furnace.

Referring to Figure 1, in order to be continuously galvanized steel sheet (1) made in the form of a roll in a steel mill, the up and down state that is continuously submerged in the zinc melting furnace (2) in which zinc is molten and taken out again must proceed. In order to continuously immerse the steel sheet 1, the zinc melting furnace 2 is provided with a galvanizing roll 10.

The galvanized roll 10 is formed of a spherical roll body 11, the shaft is formed on both sides of the roll body 11, respectively, the steel plate (1) around the roll body 11 A plurality of non-slip grooves (not shown) are continuously arranged so that slippage or flow does not occur during the transfer process.

The galvanizing roll 10 of the above configuration is installed in the zinc melting furnace 2 through a pair of fixed mounting base 20 so as not to completely sink in the zinc melting furnace 2, and protrudes on both sides of the roll body 11 By using the shaft that is rotatably coupled to the fixed mounting 20 to guide the continuous transfer of the steel sheet (1) to free rotation. To this end, a fixing hole is formed in the fixing stand 20 so that the shaft can be inserted, and the coupling is made by inserting the shaft into the rotating hole.

In addition, a stopper is attached to an outer portion of the fixed mounting base 20 in which the rotating hole is formed, so that the galvanized roll 10 is horizontal without any bias between the pair of fixed mounting units 20. It can be installed and operated in a state.

Therefore, in the state where the zinc melting furnace 2 and the zinc plating roll 10 are installed in the above-described working place, the galvanizing roll 10 is immersed in the zinc melting furnace 2 with the tip of the steel sheet 1 produced in roll form. Continuous molten plating of the steel sheet (1) through a series of processes that are continuously transferred past the lower end of the).

Meanwhile, as the steel sheet 1 is continuously transferred, the galvanized roll 10 inevitably rotates freely, and the steel sheet 1 supplied from the upper part of the zinc melting furnace 2 has a lower portion of the galvanized roll 10. The shaft (not shown), which is the center of rotation of the galvanized roll 10, is continuously discharged from the upper direction again and the upper part of the rotating hole (not shown) of the fixed mounting table 20 by the transfer pressure of the steel sheet 1. The wear and tear phenomenon occurs.

In other words, when the rotating hole is worn out due to the friction of the shaft, which is mainly made of stainless steel, the entire mounting bracket on which the rotating hole is formed must be replaced. However, when the bearing member is used in combination with the rotating hole, the worn bearing Since only the member can be replaced, the economical efficiency and work convenience will be increased.

In addition, the outer part of the shaft in close contact with the bearing member is covered with a separate protective cover and welded to replace only the protective cover instead of replacing the galvanized roll 10 at the end of the service life as in the fixed mounting stand.

Here, the lower end of the bearing member to perform the role as described above to buffer the transfer pressure of the galvanized roll 10 generated by the steel sheet 1 to slow down the wear progress, and to replace the galvanized roll 10 To extend, the coating composition for the hot dip galvanized bath member of the present invention can be coated on the member. The coating composition can be used to coat metals including steel, stainless steel, cast iron, nickel metals.

On the other hand, the term "hot dip galvanized bath member" used in the present invention means all members constituting the bath in the hot dip galvanizing process, for example, the shaft protruding on both sides of the roll body 11, fixed It may be a mounting table 20, a bearing, a rotating hole formed in the fixed mounting table, and / or a stopper. In addition, the coating composition may be applied to a cam, a guide roller, a conveyor screw, and the like.

According to the present invention, the coating composition for the hot dip galvanized bath member is 40 to 50% by weight of WC, 20 to 30% by weight of Cr, 10 to 20% by weight of Ni, 8 to 15% by weight of Co, 0.1 to 5 Weight percent Si and 0.1 to 5 weight percent B.

The WC is added to improve the wear resistance, if less than 40% by weight of the wear resistance is inferior, if more than 50% by weight of the wear resistance is increased but the bonding strength with the member tends to be inferior. In addition, Cr is added for corrosion resistance, and if it is less than 20% by weight, the corrosion resistance is inferior, and if it exceeds 30% by weight, there is a tendency that properties such as wear resistance and heat resistance are inferior while there is little improvement in corrosion resistance. The Ni is also added for corrosion resistance, if less than 10% by weight is poor in corrosion resistance, if it exceeds 20% by weight, there is a tendency that other physical properties such as wear resistance and heat resistance is inferior with little improvement in corrosion resistance. Thus, the significant improvement of corrosion resistance was seen by using Cr and Ni together.

On the other hand, Co is added for heat resistance, if less than 8 weight is less heat resistance, if more than 15% by weight tends to be poor in properties such as wear resistance and corrosion resistance. The Si is also added for heat resistance, and if less than 0.1% by weight has little effect of addition, when it exceeds 5% by weight heat resistance is improved but other physical properties such as wear resistance and corrosion resistance tends to be inferior.

Finally, the composition of the present invention contains B as an essential ingredient. The lowering the melting point of the coating composition enables the high-speed spraying, and can improve the bonding strength between the member and the coating composition. If the amount of B added is less than 0.1 weight, there is little effect of addition, and if it exceeds 5 weight%, other physical properties such as wear resistance, heat resistance and corrosion resistance tend to be inferior.

According to a preferred embodiment of the present invention, 40 to 50% by weight of WC, 20 to 30% by weight of Cr, 10 to 20% by weight of Ni, 8 to 15% by weight of Co, 0.1 to 5% by weight of Si and The mixed powder composed of 0.1 to 5% by weight of B is melted at 1000 to 1400 ° C., and then ground again to a particle size of 40 to 100 μm. Then, the pulverized product is sprayed at a high speed of Mach 3 to 5 and coated on the hot dip galvanized bath member in a semi-melt state.

In the coating composition according to the present invention, the spraying temperature at the time of the ultra-high spraying is maintained at about 500 to 600 ° C., and at about 500 to 600 ° C., the composition is semi-melted to allow coating on the member. In the present invention, the composition is designed to be in a semi-melt state at about 500 ~ 600 ℃.

At this time, the thickness of the composition coated on the surface of the molten zinc bath member is preferably 0.2 to 0.5 mm, but less than 0.2 mm, abrasion resistance is inferior, and when the thickness exceeds 0.5 mm, stress tends to occur and cracks are generated.

As such, the molten zinc bath member coated in accordance with the present invention not only has excellent wear resistance, zinc corrosion resistance and heat resistance, but the composition is also capable of ultra-fast spraying and is thus simply coated on the molten zinc bath member. In addition, since the coating is possible at room temperature, there is an effect of coating without thermal deformation of the member. Therefore, it is a very useful invention such that the productivity and economics of the continuous hot dip plating process for continuous zinc plating the steel sheet can be improved at the same time.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are not intended to limit the scope of the present invention.

Example 1

45 wt% WC powder, 25 wt% Cr powder, 16 wt% Ni powder, 12 wt% Co powder, 1 wt% Si powder, and 1 wt% B powder, followed by mixing at about 1200 ° C. It melted at, and the average particle size was ground to 40 ~ 100㎛ to prepare a coating composition for a hot dip galvanized bath member of the present invention.

The pulverized coating composition was sprayed on a stainless disc of 10 cm in diameter and 30 mm thick using SuperJet Eutalloy torch at a high speed of about Mach 4 and coated at a thickness of about 0.3 mm in a semi-melt state.

The disk thus obtained was heated to about 700 ° C. using a torch, and then the surface of the coating was polished with a polishing machine, and the wear resistance of the coating layer was measured according to the polishing time of 1 minute to evaluate wear resistance. In addition, the corrosion resistance and heat resistance was measured by the Al-45% Zn melt deposition test, the operating conditions are as follows.

Rotating Speed: 120rpm

Idle speed: 30rpm

Immersion cycle: immersion (7.5 minutes) ↔ air cooling (1 minute)

Melt: Al-45% Zn

Temperature: 650 ℃

As a result, the coating composition according to the present embodiment exhibited a wear resistance of about 2 mg per minute, and was able to confirm a very good wear resistance than about 7 mg of WC per minute, and the damage time according to the molten metal was It exhibited excellent corrosion resistance and heat resistance at about 630 hours or more, and WC / 12Co was 233 hours as a control.

In addition, after coating the composition with a thickness of about 0.3 mm on the shaft and bearing of the continuous hot-dip galvanizing process for continuous zinc plating of the steel sheet, the actual continuous hot-dip plating process was carried out, and then processed 36,000 tons (5 replacements) Compared with the 7,500 tons (one replacement) of the prior art (using uncoated shafts and bearings in the continuous hot dip plating process), the effect was five times better.

1: steel sheet 2: zinc melting furnace
10: galvanized roll 11: roll body
20: fixed mount

Claims (5)

delete delete Mixture consisting of 40-50 wt% WC, 20-30 wt% Cr, 10-20 wt% Ni, 8-15 wt% Co, 0.1-5 wt% Si and 0.1-5 wt% B Providing a powder;
Melting the mixed powder and providing a pulverized product ground to a particle size of 40 to 100 µm; And
Spraying the pulverized product at a high speed of Mach 3 to 5 and a spraying temperature of 500 to 600 ° C. to coat the hot dip galvanized bath member in a semi-melt state.
A surface-coated molten zinc bath member coated with a thickness of 0.2 to 0.5 mm on the surface of the molten zinc bath member by the method of claim 3.
The method of claim 4,
The bath member is a hot dip zinc bath member, characterized in that the shaft, the fixed mounting, the bearing, the rotating hole formed in the fixed mounting, the stopper or a combination thereof.

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