KR19980043113A - Manufacturing method of ceramic plasma spraying of immersion roll (SIEN ROL) and support roll (STAA イ ル イ ン イ ン ル ROL) installed in a bath (POT) in the equipment for manufacturing continuous molten aluminum plated steel sheet - Google Patents

Abstract

(Purpose) The behavior in the plating bath is very important in order to improve the surface property of hot-dip galvanized steel sheet. The wear and erosion parts of iron-based dip rolls and support rolls are transferred to the surface of the plated steel sheet during continuous hot-dip plating, and thus deteriorate the surface properties. In order to solve the problem of shortening the life of iron-based immersion roll, an object of the present invention is to provide a method for manufacturing a multi-stage ceramic coated immersion roll and support roll excellent in wear resistance and corrosion resistance in a molten aluminum plating bath.

(Composition) The surface roughness of the roll surface was impregnated with iron-based grit using the surface shot blasting machine of the immersion roll or the support roll, and then degreased, washed with water, dried, and then cobalt 50-60wt%, chromium 25-30wt%, 60 to 10% of cobalt, 30 to 5% of chromium, 5 to 5% of tungsten and tungsten were first sprayed on the surface of the mixed powder of 5 to 10 wt% of nickel, 5 to 7 wt% of tungsten and 0.5 wt% of carbon. 4.5wt%, carbon 0.5wt% mixed powder, alumina 94wt%, silica 1.0wt%, calcium oxide 5wt% mixed powder at a ratio of 50:50, and the secondary spray treatment to about 100㎛ A mixture of 94 wt% alumina, 5 wt% calcium oxide, and 1 wt% silica was thermally sprayed on the surface of the thermally sprayed roll at about 500 µm, and 70 wt% of alumina, 25 wt% of zirconia, and 5 wt% of silica were applied to the third thermally sprayed roll. Molten aluminum plating steel by 4th spray treatment of mixed powder of To prepare a multi-step preparative process sprayed ceramic-coated immersion roll or support roll.

Description

Manufacturing method of ceramic plasma spraying of immersion roll (SION ROL) and support roll (STAAIIIINN ROL) installed in bathtub (POT) in equipment for manufacturing continuous molten aluminum plated steel sheet

The present invention relates to a manufacturing method for the ceramic plasma spraying of the immersion roll and the support roll installed in the bath (POT) in the equipment for manufacturing continuous molten aluminum plated steel sheet.

In the prior art, continuous molten zinc, zinc-aluminum, aluminum plated steel sheet is subjected to continuous annealing heat treatment to ensure workability in a reducing atmosphere, and then hot dip galvanizing bath, zinc-aluminum alloy plating bath or pure molten aluminum plating bath, pure melt The reason why 5-12% of silicon is added to molten zinc, zinc-aluminum and aluminum-coated steel sheet by controlling the plating adhesion amount by strong air pressure after plating in a molten plating bath in which silicon is added to aluminum by 5-12% is weak during processing. This is to suppress cracking such as plating caused by the alloy layer.

In the continuous plating of steel sheets, there are immersion rolls in the plating equipment. These immersion rolls are eroded by zinc and aluminum, and steel-based immersion rolls are caused by zinc and aluminum-iron alloying as the steel sheet is continuously rubbed with the rolls. Erosion of the surface is generated by the wear caused by the erosion of the immersion roll is transferred to the surface of the plated steel sheet to produce a surface defect of the product.

In other words, Al-Si melted in the Si 5-12 wt%, Al 95-88 wt% plating bath in the manufacture of molten aluminum plated steel sheet is made of Al-Si by the interdiffusion reaction with the surface of the existing iron-based (stallite or SUJ steel) immersion roll. Since the Fe-based alloy layer is formed and the alloy layer is transferred to the surface of the steel sheet to lower the surface property, the immersion rolls need to be replaced and the operation must be stopped for the replacement key.

As shown in Fig. 1, the continuous molten plating bath is composed of one immersion roll and two support rolls.

The steel sheet continuously passes through the immersion roll, and two support rolls are installed in the plating bath to prevent the steel sheet from shaking because a strong air pressure is blown directly above the plating bath to control the coating amount.

After passing through a tensile straightener for skin pass and flatness correction, it is finally producted after lubricating post-treatment chromate or oil.

The behavior in the plating bath is very important in order to improve the surface properties of the hot-dip galvanized steel sheet. The wear and erosion parts of the iron-based dip rolls and support rolls are transferred to the surface of the plated steel sheet during continuous hot dip plating, and the surface properties are deteriorated. In order to solve the problem that the roll life is shortened, an object of the present invention is to provide a method for producing a multi-stage ceramic coated dip roll having excellent wear resistance and corrosion resistance in a molten aluminum plating bath.

1 is a schematic illustration of a plating facility in which a ceramic coating dip roll for manufacturing continuous molten aluminum plated steel sheet of the present invention is used.

Figure 2a is a cross-sectional view of the structure of the multi-stage thermally sprayed ceramic coated immersion roll excellent in wear resistance and corrosion resistance of the present invention.

Figure 2b is a structure diagram of a multi-stage thermally sprayed ceramic coating dip roll excellent in wear resistance and erosion resistance of the present invention.

Figure 3 is a schematic process diagram of a multi-stage ceramic thermal spray coating immersion roll manufacturing equipment for producing a molten aluminum plated steel sheet excellent in wear resistance and erosion resistance of the present invention.

Figure 4 is a graph comparing the erosion depth after immersing a multi-stage ceramic coating dip roll of the present invention and the conventional iron-based dip roll in a molten aluminum plating bath for 10 days.

5 is a graph showing the surface hardness test results of the multi-stage ceramic coating dip roll and the conventional design dip roll of the present invention.

FIG. 6 is a partial cross-sectional view schematically showing a heating apparatus for reducing thermal shock before placing the multi-stage sprayed ceramic coated immersion roll of the present invention into a plating bath.

(Explanation of the sign)

One … Payoff reel 2. Entry cleaning 3. Annealing furnace 4. Top roll

5... Skin Pass 6. Tension leveler 7. Tension reel 10. Aluminum bathtub

11. Think 12. Stableizing Roll

In order to solve the above problems, the technical means to be solved by the present invention is characterized by performing a multi-stage sprayed ceramic coating on the existing iron-based roll surface in order to prevent the surface erosion and wear of the iron-based immersion roll and the support roll.

Best mode for carrying out the invention is described as follows.

If the coefficient of thermal expansion of the material and ceramic layer is different, it is easy to generate cracks between the material and the ceramic plating layer due to the thermal shock caused by the difference in the coefficient of thermal expansion when the dip roll is heated and then put into or out of the plating bath. Since the ceramic coating layer on the surface of the immersion roll is easily broken.

Therefore, in order to reduce thermal shock of the iron substrate and the ceramic plating layer, the multi-stage spraying treatment is performed in four steps. Figure 3 shows a brief description of the sprayed plated steel sheet equipment used.

In order to improve the abrasion resistance on the surface of the iron material during the thermal spraying treatment, first, the cobalt-chromium alloy powder is first sprayed to a thickness of about 100 μm, and then cobalt-chromium alloy powder, alumina, silica, and calcium oxide are mixed to about 100 μm. After the second spray treatment, the third thermal spraying treatment of alumina, silica and calcium oxide is about 500㎛, and the fourth mixture is thermally sprayed about 60 to 70㎛ for alumina, zirconia and silica to improve hardness and wear resistance.

50 ~ 60wt% of cobalt, 25 ~ 30wt% of chromium, 5 ~ 10wt% of nickel, 5 ~ 7wt% of tungsten, 0.5wt% of carbon component powder is applied to iron rolls when ceramic spray layer is worn by cracks. This is to prevent wear and to improve corrosion resistance.

Then, the second thermally sprayed cobalt 60wt%, chromium 30wt%, nickel 5wt%, tungsten 4.5wt%, carbon 0.5wt% powder and alumina 94wt%, silica 1.0wt%, calcium oxide 5wt% in a ratio of 50:50 The mixture was thermally sprayed to prevent thermal shock of the cobalt-chromium metal and the ceramic thermal sprayed layer, followed by tertiary thermal spraying of 94% by weight of alumina, 1.0% by weight of silica, and 5% by weight of calcium oxide.

Finally, the fourth spray treatment is a final spray treatment of alumina 70wt%, zircoa 25wt%, silica 5wt% powder to improve the hardness of the ceramic sprayed layer.

In this way, after the immersion by the multi-step spray treatment to prevent thermal shock between the surface and the ceramic coating layer, the ceramic coating significantly improved the erosion and wear phenomenon by the molten aluminum of the immersion roll.

In order to improve the adhesion between the heat-treated body and the ceramic coating layer, the surface roughness is Ra 8 to 10 μm by shot blast treatment on the iron surface to be sprayed.

Thereafter, degreasing and washing with water are dried and sprayed.

Degreased with thinner to remove foreign substances such as oil and moisture.Then, the surface to be sprayed at 80-120 ℃ was heated evenly by using a propane torch to dry the water after washing with water and then completely dried. do.

The surface roughness after spraying is set to Ra 6 to 8 µm. Thermal spraying conditions were as shown in Table 1.

Table 1. Thermal treatment conditions

Atmosphere gas Argon / Hydrogen Gas pressure 75/50, 100 / 50㎏ / ㎠ Champion Range 120 cm Material supply 18 to 35 g / ㎡ Thermal Spray Thickness 0.5 to 1.5 mm

In order to minimize thermal expansion when the plating bath of the multi-stage sprayed ceramic spray immersion roll is introduced, the plating is performed after heating at 500 ° C. or more in a heating facility for 5 hours and then placing it in the plating bath.

In order to reduce the separation of the multi-stage thermally treated ceramic coating layer and iron material during the introduction of the plating bath, the immersion roll surface is heated to 100 ° C. for 1 hour and finally heated to 500 ° C. or higher for 5 hours. To prevent peeling of the ceramic coating layer.

In addition, dross and aluminum deposits on the surface of the roll were removed before coagulation after use.Also, after cooling, rolls of aluminum particles and dross on the surface were washed by washing with an alkali solution dissolved in a 30 wt% aqueous solution of caustic soda. Remove surface deposits.

Example

For example, it will be described in detail as follows. Although preferred embodiments of the present invention will be described by way of example, structural changes and other examples can be made without departing from any of the spirit or scope of the invention, and the embodiments are not intended to limit the invention.

Example 1

After grinding the immersion roll of 1,700 mm in length and 600 mm in diameter and the supporting roll of 1,700 mm in length and 200 mm in diameter on the lathe to improve the adhesion between the ceramic thermal sprayed layer and the surface of the roll, a shot blast machine is used. grit) to give the surface roughness of the roll surface.

The surface roughness at this time is Ra 8 ~ 10㎛ surface roughness, degreased with a thinner to remove foreign substances such as oil and moisture, and sprayed at 80 ~ 120 ℃ with a propane torch to dry the moisture after cleaning. After the surface is uniformly heated and completely dried, 60 wt% of cobalt, 30 wt% of chromium, 5 wt% of nickel, 4.5 wt% of tungsten and 0.5 wt% of carbon are thermally sprayed, and 60 wt% of cobalt, 30 wt% of chromium, A mixture of 5wt% nickel, 4.5wt% tungsten and 0.5wt% carbon powder, 94wt% alumina, 1wt% silica, and 5wt% quicklime powder is mixed at a ratio of 50:50 to the secondary sprayed surface. After the treatment, tertiary thermal spraying was performed on the surface of the secondary thermally sprayed mixture of 94 wt% alumina, 1 wt% silica, and 5 wt% quicklime, followed by tertiary spraying of the mixed powder of 70 wt% alumina, 25 wt% zirconia, and 5 wt% silica. Fourth spraying was performed on the treated surface. The surface roughness after spraying was Ra 6-8 탆.

An enlarged cross-sectional photograph of the immersion roll prepared in Example 1 is also shown in Figure 2b.

Example 2

It carried out similarly to Example 1 except having replaced the immersion roll instead of the support roll in Example 1.

In order to evaluate the erosion resistance of the molten aluminum bath of the thermally sprayed immersion roll with such a material, the multi-stage sprayed ceramic coated immersion roll and iron roll of Example 1 were subjected to 10 days at 680 ° C., Si 5-12 wt%, Al 95˜ The result of immersing in 88 wt% plating bath is shown in FIG.

In the case of the existing immersion roll of the spring steel system, the erosion phenomenon of about 2.3 mm occurred, but the erosion phenomenon of the multi-stage sprayed ceramic coated immersion roll of Example 1 of the present invention did not occur.

5 shows that the hardness of the present application is much superior to that of the conventional one as a result of the surface hardness measurement of the roll and the iron roll of Example 1 of the present application.

Claims (4)

The surface roughness of the roll surface is impregnated with iron-based grit using the surface shot blast of the immersion roll or the supporting roll, and then degreased, washed with water, dried, and then cobalt 50-60wt%, chromium 25-30wt%, nickel 5- 10wt%, tungsten 5 ~ 7wt%, carbon 0.5wt% mixed powder is primary sprayed to about 100㎛, and the surface of primary sprayed roll is 60wt% cobalt, 30wt% chromium, 5wt% nickel, 4.5wt% tungsten , 0.5 wt% carbon mixed powder was first sprayed, cobalt 50 to 60 wt%, chromium 25 to 30 wt%, nickel 5 to 10 wt%, tungsten 5 to 7 wt%, carbon 0.5 wt% mixed powder and alumina 94wt %, Silica 1.0wt%, calcium oxide 5wt% mixed powder at a ratio of 50:50, and secondary spray treatment of about 100㎛, 94wt% alumina, 5wt% calcium oxide on the secondary sprayed roll surface , 3wt% of silica mixed powder of 1wt%, tertiary sprayed on the surface of the 3rd sprayed, alumina 70wt%, zirconia 25wt%, the silica to a powder mixture of 5wt% quaternary spraying process so 60~70㎛ method for manufacturing a continuous hot-dip aluminum coated steel strip for producing multi-stage thermal spray process a ceramic-coated roll is immersed or support roll. The method according to claim 1, wherein the surface roughness Ra of the roll is 4 to 6 µm. The method of manufacturing a multi-stage thermally sprayed ceramic coated immersion roll or support roll for manufacturing continuous molten aluminum plated steel sheet according to claim 1, characterized by degreasing with a thinner. 10. The method of claim 1, wherein the propane torch is dried at about 80-120 ° C. to produce moisture.