KR101426682B1 - Grate bar with thermally sprayed aluminum oxide and fabricating method thereof - Google Patents

Abstract

Disclosed is a Great Bar of aluminum oxide sprayed with improved durability with improved heat resistance, corrosion resistance, abrasion resistance, and impact resistance, and a method for producing the same. The disclosed Great Bar has a base formed by casting and an aluminum oxide layer formed by laminating aluminum oxide (Al ₂ O ₃ ) sprayed on the surface of at least a part of the base .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a Great Bar coated with aluminum oxide and a method for producing the same,

The present invention relates to a grate bar mounted on a sintering furnace used in a sintering process of a steel mill and a method of manufacturing the same.

Iron ore, a raw material used to produce steel in steel mills, is an ore containing 30 to 70% iron (Fe) and is rich in iron (Fe) and contains sulfur (S), phosphorus (P), copper Although it is ideal that the same harmful components are small and the size is constant, these iron ores are not common and it is difficult to input them into the blast furnace as they are different in quality, composition and shape depending on their origin. Therefore, to make the iron ore quality uniform before putting it in the blast furnace, it is called a sintering process.

FIG. 1 is a view showing a sintered light producing process using a sintering furnace, and FIGS. 2 and 3 are a side sectional view and a perspective view showing the structure of a sintering furnace. 1 to 3, an iron ore ore 1 is charged through an upper hopper 4 and a surge hopper 3 on the upper side of a Great Bar 20 of a sintering furnace 9, do. The sintering furnace 9 loaded with the iron ore Ore 1 moves along the rail 13. At this time, the ignition furnace 7 is operated, and the iron ore ore loaded in the sintering furnace 9 is ignited while passing through the ignition furnace 7. The ignited ore is gradually sintered from the upper part to the lower part by the downward suction force generated by the fan 5. The air by downward sucking is discharged through a wind box 6. The sintered ores that have been sintered are transferred to the cooler 8. The sintering furnace 9, in which the sintered ores are released and becomes empty, rotates the endless track and returns to the side of the hoppers 3 and 4. The iron ore raw material is charged again and the sintering proceeds.

A number of great bars 20 are arranged in the lateral direction on the surface of the body 10 of the sintering furnace 9 and an iron ore ore 1 is loaded on the upper side of the great bar 20. The great bars 20 are typically arranged in three rows. Side walls 11 fixed by locking pins 14 are provided at both side ends of the sintering furnace 9. During the sintering process the sintering furnace 9 is moved by means of a wheel 12 in contact with the surface of the rail 13.

In the sintering process described above, the temperature inside the sintering furnace 9 is raised to 1000 ° C or higher, and the Great Bar 20 is continuously exposed to such a high temperature environment. It is also required to support heavy iron ore feedstock and is exposed to high temperature, high pressure wind containing many fine particles formed by the suction force of the fan 5. As a result, cracks are generated on the surface of the Great Bar 20 and the surface is oxidized, resulting in poor durability. Since the durability of the Great Bar 20 requires a short replacement cycle, it causes an increase in the cost of the sintering process and further the steel making process.

Korean Patent Registration No. 10-0833007 Korean Registered Patent No. 10-1131100

The present invention provides a Great Bar of aluminum oxide (Al ₂ O ₃ ) sprayed with improved durability with improved heat resistance, corrosion resistance, abrasion resistance, and impact resistance, and a method for producing the same.

In addition, the present invention provides a Great Bar having a surface property that is surface treated with a spray coating of aluminum oxide (Al ₂ O ₃ ) and can withstand harsh environments for a longer time, and a method for producing the same.

The present invention relates to a sintering furnace which is disposed in a sintering furnace to support a raw material for sintering and comprises a base formed by casting and an aluminum oxide (Al ₂ O (Al ₂ O ₃ )) sprayed on the surface of at least a part of the base ₃ ) formed by laminating an aluminum oxide layer formed on the surface of the substrate.

The thickness of the aluminum oxide layer may be 0.2 to 1.0 mm.

The Great Bar of the present invention may further comprise a buffer layer formed by laminating Ni ₅ Al sprayed between the base and the aluminum oxide layer.

The thickness of the buffer layer may be 30 to 50 탆.

In addition, the present invention is a base-forming step of forming a base (base) the cast steel (鑄物用鋼) for the casting (鑄造), and aluminum oxide on the surface of at least a portion of the base (Al ₂ O ₃₎ spraying And forming an aluminum oxide layer by spraying (spraying) the aluminum oxide layer.

The aluminum oxide layer forming step may include an aluminum oxide plasma spraying step of spraying aluminum oxide (Al ₂ O ₃ ) powder onto a surface of at least a part of the base by plasma.

The method of manufacturing a Great Bar according to the present invention is characterized in that a buffer layer is formed between the base forming step and the aluminum oxide layer forming step by spraying Ni ₅ Al on the surface of at least a part of the base to form a buffer layer Step may be further included.

The buffer layer forming step may include a Ni ₅ Al plasma spraying step of spraying Ni ₅ Al powder onto a surface of at least a part of the base.

The Great Bar of the present invention has an aluminum oxide layer formed by spraying aluminum oxide (Al ₂ O ₃ ) on the surface of a base which is a cast product, and is superior in heat resistance, corrosion resistance, abrasion resistance, The impact resistance is greatly improved, and the durability is improved. In addition, this results in a longer replacement cycle of the Great Bar, thereby reducing the cost of the sintering operation.

Fig. 1 is a view showing a sintered light producing process using a sintering furnace.
2 and 3 are a side sectional view and a perspective view showing the structure of the sintering furnace.
4 is a perspective view of a Great Bar according to an embodiment of the present invention.
5 is a view for explaining a method of manufacturing a Great Bar according to an embodiment of the present invention.
6 is an enlarged cross-sectional view of a surface of a Great Bar according to an embodiment of the present invention.
Figures 7a and 7b is a photograph showing the wear resistance test result using the Great bar specimen, Figure 7a is an aluminum (Al ₂ O ₃₎ The test results of the spraying are not coated specimens, Figure 7b is an aluminum oxide (Al ₂ O ₃ oxide ) This is a photograph showing test results of a spray-coated specimen.
Figures 8a and 8b are photographs showing the salt spray test result using the Great bar specimen, Figure 8a is an aluminum oxide (Al ₂ O ₃₎ The test results of the spraying are not coated specimens, Figure 8b is an aluminum (Al ₂ O oxide ₃ ) A photograph showing test results of a spray-coated specimen.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The terminology used herein is a term used to properly express the preferred embodiment of the present invention, which may vary depending on the intention of the user or operator or the custom in the field to which the present invention belongs. Therefore, the definitions of these terms should be based on the contents throughout this specification.

FIG. 4 is a perspective view of a Great Bar according to an embodiment of the present invention, FIG. 5 is a view for explaining a method of manufacturing a Great Bar according to an embodiment of the present invention, And FIG. Referring to FIG. 4, the Great Bar 100 is a member in the form of a Greek letter π, which is inserted horizontally into a beam 101 supporting the iron ore raw material and inside the sintering furnace 9 (see FIG. 1) And a spacer 107 protruded so as not to be in close contact with the adjoining great bar 100. Hot hot wind flows through the flow path between the adjacent great bars 100 formed by the spacer 107. [

Referring to FIGS. 4 and 6 together, the Great Bar 100 includes a base 110, a buffer layer 112, and an aluminum oxide layer 114. The method for manufacturing the Great Bar 100 includes a step of forming the base 110, a step of forming the buffer layer 112, and a step of forming the aluminum oxide layer 114. The step of forming the base 110 is a step of forming a base 110 by casting steel for casting. The cast steel may be a high-chromium heat-resistant steel containing at least 28 wt% of chromium (Cr).

The buffer layer 112 is formed by spraying Ni ₅ Al on the surface of the base 110 to form the buffer layer 112. The buffer layer 112 may be formed on the surface of the entire portion of the base 110 and may be formed on only a part of the surface such as the beam 101, for example. The buffer layer 112 prevents peeling or distortion of the aluminum oxide layer 114 due to the difference in thermal expansion coefficient between the base 110 and the aluminum oxide layer 114 and improves the adhesion of the aluminum oxide layer 114.

If the thickness L2 of the buffer layer 112 is too small, the adhesion of the aluminum oxide layer 114 can not be enhanced. If the thickness L2 is too large, the formation cost of the buffer layer 112 increases and the formation time of the buffer layer 112 becomes long Productivity also deteriorates. Therefore, the thickness L2 of the buffer layer 112 may be 30 to 50 mu m.

The step of forming the aluminum oxide layer 114 is a step of forming an aluminum oxide layer 114 by spraying aluminum oxide (Al ₂ O ₃ ) on the surface of the base 110 on which the buffer layer 112 is formed . The aluminum oxide layer 114 may be formed in the same region as the region where the buffer layer 112 is formed and may be formed on the surface of the entire portion of the base 110 and may be formed, As shown in Fig. If the thickness L1 of the aluminum oxide layer 114 is too thin, the effect of improving abrasion resistance, corrosion resistance, heat resistance and the like is insignificant. On the other hand, if it is too thick, not only the formation of the aluminum oxide layer 114 by spraying is difficult but also the formation cost is increased and the productivity is also lowered. Thus, the thickness of the aluminum oxide layer 114 may be 0.2 to 1.0 mm.

The step of forming the aluminum oxide layer 114 includes an aluminum oxide (Al ₂ O ₃ ) plasma spraying step, and the step of forming the buffer layer 112 may include a step of Ni ₅ Al plasma spraying. Aluminum oxide (Al ₂ O ₃ ) plasma spraying and Ni ₅ Al plasma spraying may be performed using, for example, the plasma torch 50 shown in FIG.

The plasma torch 50 has a cathode 51 protruding in the form of a pin and a nozzle 56 surrounding the cathode 51 and in front of the cathode 51 And an anode 54 formed thereon. An inert gas such as argon, hydrogen, nitrogen or helium is supplied through the gas supply unit 61 around the cathode electrode 51 to be plasmaized between the cathode electrode 51 and the anode electrode 54, And is forwardly injected into a plasma jet 65 through the nozzle. On the other hand, cooling water is supplied to the peripheral portion of the anode electrode 54 through the cooling water supply portion 62 to prevent the torch 50 including the nozzle 54 from overheating.

Torch (50) when through the front powder input portion (58) Ni ₅ Al powder is turned carried on the plasma jet 65 is sprayed on the base 110 surface Ni ₅ Al film is formed, and the powder turned portion (58 (Al ₂ O ₃ ) powder is injected through the plasma jet 65 and is sprayed onto the surface of the base 110 to form an aluminum oxide (Al ₂ O ₃ ) coating.

The plasma spray can raise the temperature of the plasma jet 65 to an extremely high temperature of 16,500 DEG C in the nozzle 56, so that it is possible to coat the coating by using all kinds of metallic powders, Has excellent adhesion, and has a very dense coating structure. However, the aluminum oxide layer 114 and the buffer layer 112 of the present invention are not limited to those formed by plasma spraying. For example, other sprayed materials using metallic powder such as flame spraying or high- Method. ≪ / RTI >

Hereinafter, the performance of the Great Bar 100 according to the embodiment of the present invention will be described in terms of items. The following performance tests were conducted on a conventional Great Bar specimen made of a casting of a high chrome heat resistant steel material and not coated with aluminum oxide (Al ₂ O ₃ ) spray coating, a base 110 as described with reference to FIG. 6, a buffer layer 112 ), And an aluminum oxide layer (114).

≪ Hardness >

An experiment to measure Vicker? Hardness using the surface area of the indentation mark pressed against the normal Great Bar specimen and the Great Bar specimen of the present invention for 15 seconds at a load of 20 kgf using a diamond indentator with a quadrangular pyramid shape Vickers hardness (H _V) of the result, the conventional bar Great specimen 380, the Vickers hardness (H _V) of the Great bar specimen of the present invention is measured by the 569, the hardness increase is confirmed.

<Abrasion resistance test>

Figures 7a and 7b is a photograph showing the wear resistance test result using the Great bar specimen, Figure 7a is an aluminum (Al ₂ O ₃₎ The test results of the spraying are not coated specimens, Figure 7b is an aluminum oxide (Al ₂ O ₃ oxide ) This is a photograph showing test results of a spray-coated specimen. The normal Great Bar specimen in the form of a disk and the Great Bar specimen of the present invention were heated to 150 DEG C and subjected to chromizing treatment at a linear velocity of 236 mm / sec, a load of 90 N, and a friction time of 12600 seconds And the abrasion test was carried out. In the abrasion resistance test for a normal Great Bar specimen, a wear pattern as shown in FIG. 7A was formed, and a result of a wear amount of 2.55 g and a wear thickness of 0.83 mm was measured. On the other hand, in the abrasion resistance test of the Great Bar specimen of the present invention, a wear pattern as shown in FIG. 7B was formed, the result of 0.50 g of wear amount and 0.3 mm of marrow thickness was measured, and improvement of abrasion resistance was confirmed.

&Lt; Sandblast Test >

The actual environment in which the Great Bar is used is an extreme environment where large amounts of metal debris are generated and hit the Great Bar with strong pressure. The sandblast test was conducted by spraying fine sand particles at high pressure onto the surface of the Great Bar to confirm the tolerance of the Great Bar. The test was conducted by exposing it to high pressure sand for 120 seconds. As a result of the test, the surface loss rate of a normal Great Bar specimen was measured at 100% and the surface loss rate of the Great Bar specimen of the present invention was measured at 50%, confirming the improvement in resistance to high-pressure metal fragments.

<Salt spray test>

Figures 8a and 8b are photographs showing the salt spray test result using the Great bar specimen, Figure 8a is an aluminum oxide (Al ₂ O ₃₎ The test results of the spraying are not coated specimens, Figure 8b is an aluminum (Al ₂ O oxide ₃ ) A photograph showing test results of a spray-coated specimen. The actual environment in which the Great Bar is used is an extreme environment where there is a high risk of corrosion due to high temperature oxidation. The salt spray test is a test that visually confirms the degree of corrosion by spraying salt water on the Great Bar. The saline spray time was 288 hours and continued for 12 days. In the salt spray test of a normal Great Bar specimen, rust, or corrosion, occurred over the entire surface of the Great Bar specimen as shown in FIG. 8A. On the other hand, in the salt spray test of the Great Bar specimen of the present invention, as shown in FIG. 8B, only a part of the upper end or the lower end of the Great Bar specimen is rusted to a limited extent, that is, corrosion occurs.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

50: Plasma spray torch 100: Great bar
101: beam 103: fixed jaw
107: spacer 110: base
112: buffer layer 114: aluminum oxide layer

Claims (8)

And disposed in the sintering furnace to support the raw material for sintering,
A base formed by casting; And
And an aluminum oxide layer formed by laminating aluminum oxide (Al ₂ O ₃ ) sprayed on the surface of at least a part of the base. The method according to claim 1,
Wherein the aluminum oxide layer has a thickness of 0.2 to 1.0 mm. The method according to claim 1,
And a buffer layer formed by laminating Ni ₅ Al sprayed between the base and the aluminum oxide layer. The method of claim 3,
Wherein the thickness of the buffer layer is 30 to 50 占 퐉. A base forming step of casting a steel for casting to form a base; And
And an aluminum oxide layer forming step of forming an aluminum oxide layer by spraying aluminum oxide (Al ₂ O ₃ ) on the surface of at least a part of the base. 6. The method of claim 5,
Wherein the aluminum oxide layer forming step includes an aluminum oxide plasma spraying step of spraying aluminum oxide (Al ₂ O ₃ ) powder onto a surface of at least a part of the base by placing the powder on a plasma . 6. The method of claim 5,
And forming a buffer layer between the base forming step and the aluminum oxide layer forming step by spraying Ni ₅ Al on the surface of at least a part of the base, &Lt; / RTI &gt; 8. The method of claim 7,
Wherein the buffer layer forming step includes a Ni ₅ Al plasma spraying step of spraying Ni ₅ Al powder onto a surface of at least a part of the base by placing the Ni ₅ Al powder on a plasma.

Images