An antioxidant coating for ladle magnesia-carbon bricks

Abstract

The present invention relates to the technical field of coatings, and provides an antioxidant coating for ladle magnesia-carbon bricks. The raw materials include the following components in parts by weight: 30-50 parts of magnesite, 20-30 parts of alumina, 10-20 parts of tungsten carbide, 5-10 parts of binder, 5-15 parts of clay, and 5-15 parts of borosilicate glass; the binder is composed of silica sol, styrene-acrylic emulsion and zirconium acetate mixed in a mass ratio of 3-8:1:1. Through the above technical solution, the problem that the existing magnesia-carbon bricks have poor antioxidant performance when applied in ladles is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and specifically, to an antioxidant coating for ladle magnesia-carbon bricks. Background Art

[0002] As a composite refractory material, magnesia-carbon bricks are often laid in parts such as the slag line of a ladle. Before the ladle is filled with molten steel, it must be baked in the order of low fire, medium fire, and high fire in advance. Generally, the baking temperature is as high as about 1000 °C, and during the entire baking process, the time is as short as 20 - 30 h or as long as 3 - 5 days. This is extremely likely to cause the oxidation of magnesia-carbon bricks, resulting in a relatively thick oxidation and decarburization layer on the magnesia-carbon bricks, thereby affecting the service life of the magnesia-carbon bricks.

[0003] Coating an antioxidant coating on the surface of magnesia-carbon bricks is one of the important means to enhance the antioxidant ability of magnesia-carbon bricks. However, the existing antioxidant coatings have a low improvement in the antioxidant performance of magnesia-carbon bricks. Therefore, it is of great significance to develop an antioxidant coating for ladle magnesia-carbon bricks. Summary of the Invention

[0004] The present invention provides an antioxidant coating for ladle magnesia-carbon bricks, which solves the problem of poor antioxidant performance of magnesia-carbon bricks when applied in ladles in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides an antioxidant coating for ladle magnesia-carbon bricks, and the raw materials include the following components in parts by weight: 30 - 50 parts of magnesia, 20 - 30 parts of alumina, 10 - 20 parts of tungsten carbide, 5 - 10 parts of binder, 5 - 15 parts of clay, and 5 - 15 parts of borate glass;

[0007] The binder is composed of silica sol, styrene-acrylic emulsion, and zirconium acetate mixed in a mass ratio of 3 - 8:1:1.

[0008] As a further technical solution, the particle size of the silica sol is ≤ 30 nm.

[0009] When the particle size of the silica sol is ≤ 30 nm, it can enhance the thermal stability of the antioxidant coating, thereby further reducing the thickness of the oxidation and decarburization layer of the magnesia-carbon bricks.

[0010] As a further technical solution, the silica sol is cationic silica sol.

[0011] When the silica sol is cationic silica sol, it is beneficial to further improve the adhesion ability between the antioxidant coating and the surface of the magnesia-carbon bricks, thereby further enhancing the antioxidant performance of the magnesia-carbon bricks.

[0012] As a further technical solution, the tungsten carbide is zinc-doped tungsten carbide, and the preparation method of the zinc-doped tungsten carbide is as follows: Mix zinc powder and tungsten carbide evenly, sinter in vacuum, cool, crush and grind to obtain the zinc-doped tungsten carbide.

[0013] As a further technical solution, the mass ratio of the zinc powder to the tungsten carbide is 1:9 - 3:7.

[0014] When the mass ratio of the zinc powder to the tungsten carbide is 1:9 - 3:7, the oxidation resistance of the magnesia-carbon brick can be further improved.

[0015] As a further technical solution, during the vacuum sintering, the temperature is 550 - 600 °C and the time is 2 - 3 h.

[0016] As a further technical solution, the particle size of the zinc-doped tungsten carbide is 45 - 53 μm.

[0017] As a further technical solution, the particle sizes of the magnesia, alumina and tungsten carbide are each independently 45 - 75 μm.

[0018] As a further technical solution, the particle size of the magnesia is 63 - 75 μm; and / or

[0019] the particle size of the alumina is 53 - 63 μm; and / or

[0020] the particle size of the tungsten carbide is 45 - 53 μm.

[0021] As a further technical solution, the clay is one or more of Guangxi white clay, montmorillonite, and bentonite.

[0022] The addition of clay is beneficial to improving the density of the antioxidant coating, thereby further improving the oxidation resistance of the magnesia-carbon brick.

[0023] The present invention also provides a preparation method of the antioxidant coating for the ladle magnesia-carbon brick, which includes the following steps: Mix the raw materials evenly to obtain the antioxidant coating.

[0024] The present invention also provides an application of the antioxidant coating in the oxidation resistance of the ladle magnesia-carbon brick.

[0025] The working principle and beneficial effects of the present invention are as follows:

[0026] 1. In the present invention, based on the composition characteristics of the magnesia-carbon brick and the service environment, the antioxidant coating is designed, wherein:

[0027] (1) The selection of magnesia and alumina is beneficial to the tight combination of the antioxidant coating and the magnesia-carbon brick at high temperature to form a dense protective layer, preventing the diffusion of oxygen, thereby reducing the thickness of the oxidation and decarburization layer of the magnesia-carbon brick;

[0028] (2) Tungsten carbide can undergo an oxidation reaction with oxygen at high temperatures, reducing the oxygen partial pressure on the surface of the magnesia-carbon brick, hindering the diffusion of oxygen into the interior of the magnesia-carbon brick, enhancing the antioxidant performance of the magnesia-carbon brick, and reducing the thickness of the oxidation decarburization layer of the magnesia-carbon brick.

[0029] (3) A mixture of silica sol, styrene-acrylic emulsion, and zirconium acetate with a mass ratio of 3 - 8:1:1 is used as a binder. Through the synergistic effect of the three, the bonding effect between the antioxidant coating and the magnesia-carbon brick can be enhanced, enabling the antioxidant coating to be tightly coated on the surface of the magnesia-carbon brick, thereby enhancing the antioxidant performance of the magnesia-carbon brick. In addition, the silicon dioxide in the silica sol can block the pores on the surface of the magnesia-carbon brick to prevent oxygen diffusion. The styrene-acrylic emulsion can not only increase the viscosity of the binder but also prevent the antioxidant coating from cracking. Zirconium acetate can promote the formation of a dense magnesium oxide protective film by magnesium elements while improving the bonding performance, reducing the thickness of the oxidation decarburization layer of the magnesia-carbon brick.

[0030] 2. In the present invention, by doping zinc into tungsten carbide, on the one hand, the oxygen partial pressure on the surface of the magnesia-carbon brick can be further reduced, and on the other hand, it can promote the nucleation of oxides in the antioxidant coating to form a continuous and dense oxide protective film, thereby further improving the antioxidant performance of the magnesia-carbon brick and further reducing the thickness of the oxidation decarburization layer of the magnesia-carbon brick. Specific Embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0032] In the following examples and comparative examples, unless otherwise specified, magnesia is purchased from Yingkou Renxing Magnesium Industry Co., Ltd. with a particle size of 75 μm; alumina is purchased from Hebei Aiminite Chemical Technology Co., Ltd. with a particle size of 53 μm; tungsten carbide is purchased from Hebei Pengsai Metal Materials Co., Ltd. with a particle size of 45 μm; styrene-acrylic emulsion is purchased from Wuhan Jiyesheng Chemical Co., Ltd. with the brand JYS15415; zirconium acetate is purchased from Hubei Xinghengye Technology Co., Ltd. with a particle size of 45 μm; zinc powder is purchased from Beijing October New Materials Technology Co., Ltd. with a particle size of 48 μm; Guangxi white clay is purchased from Guangxi Nanning Jinpinwang Mining Co., Ltd. with a particle size of 53 μm; boron glass is purchased from Zhengzhou Longxiang Ceramics Co., Ltd. with a particle size of 45 μm.

[0033] Example 1

[0034] A preparation method of an antioxidant coating for ladle magnesia-carbon bricks, comprising the following steps: By weight, 30 parts of magnesite, 20 parts of alumina, 10 parts of tungsten carbide, 5 parts of binder, 5 parts of Guangxi white clay, and 5 parts of borate glass are ultrasonically mixed evenly to obtain the antioxidant coating;

[0035] Among them, the binder is composed of silica sol (purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd., model NS60-30 / 1, particle size 60nm), styrene-acrylic emulsion and zirconium acetate mixed in a mass ratio of 3:1:1.

[0036] Example 2

[0037] A preparation method of an antioxidant coating for ladle magnesia-carbon bricks, comprising the following steps: By weight, 50 parts of magnesite, 30 parts of alumina, 20 parts of tungsten carbide, 10 parts of binder, 15 parts of Guangxi white clay, and 15 parts of borate glass are ultrasonically mixed evenly to obtain the antioxidant coating;

[0038] Among them, the binder is composed of silica sol (purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd., model NS60-30 / 1, particle size 60nm), styrene-acrylic emulsion and zirconium acetate mixed in a mass ratio of 8:1:1.

[0039] Example 3

[0040] A preparation method of an antioxidant coating for ladle magnesia-carbon bricks, comprising the following steps: By weight, 50 parts of magnesite, 30 parts of alumina, 20 parts of tungsten carbide, 10 parts of binder, 15 parts of Guangxi white clay, and 15 parts of borate glass are ultrasonically mixed evenly to obtain the antioxidant coating;

[0041] Among them, the binder is composed of silica sol (purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd., model NS30-30 / 1, particle size 30nm), styrene-acrylic emulsion and zirconium acetate mixed in a mass ratio of 8:1:1.

[0042] Example 4

[0043] A preparation method of an antioxidant coating for ladle magnesia-carbon bricks, comprising the following steps: By weight, 50 parts of magnesite, 30 parts of alumina, 20 parts of tungsten carbide, 10 parts of binder, 15 parts of Guangxi white clay, and 15 parts of borate glass are ultrasonically mixed evenly to obtain the antioxidant coating;

[0044] Among them, the binder is composed of cationic silica sol (purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd., model P30-30 / 1, particle size 30nm), styrene-acrylic emulsion and zirconium acetate mixed in a mass ratio of 8:1:1.

[0045] Example 5

[0046] The difference between this example and Example 4 is only that, in this example, tungsten carbide is zinc-doped tungsten carbide, and the preparation method of zinc-doped tungsten carbide is as follows: Mix 1 part of zinc powder and 19 parts of tungsten carbide evenly, sinter them under vacuum at 575 °C for 1.5 h, cool, crush and grind them to obtain zinc-doped tungsten carbide with a particle size of 45 μm.

[0047] Example 6

[0048] The difference between this example and Example 4 is only that, in this example, tungsten carbide is zinc-doped tungsten carbide, and the preparation method of zinc-doped tungsten carbide is as follows: Mix 10 parts of zinc powder and 10 parts of tungsten carbide evenly, sinter them under vacuum at 575 °C for 1.5 h, cool, crush and grind them to obtain zinc-doped tungsten carbide with a particle size of 45 μm.

[0049] Example 7

[0050] The difference between this example and Example 4 is only that, in this example, tungsten carbide is zinc-doped tungsten carbide, and the preparation method of zinc-doped tungsten carbide is as follows: Mix 2 parts of zinc powder and 18 parts of tungsten carbide evenly, sinter them under vacuum at 575 °C for 1.5 h, cool, crush and grind them to obtain zinc-doped tungsten carbide with a particle size of 45 μm.

[0051] Example 8

[0052] The difference between this example and Example 4 is only that, in this example, tungsten carbide is zinc-doped tungsten carbide, and the preparation method of zinc-doped tungsten carbide is as follows: Mix 6 parts of zinc powder and 14 parts of tungsten carbide evenly, sinter them under vacuum at 575 °C for 1.5 h, cool, crush and grind them to obtain zinc-doped tungsten carbide with a particle size of 45 μm.

[0053] Comparative Example 1

[0054] The difference between this comparative example and Example 1 is only that, in this comparative example, no silica sol and zirconium acetate are added, and the weight fraction of the styrene-acrylic emulsion added is 5 parts.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is only that, in this comparative example, no styrene-acrylic emulsion and zirconium acetate are added, and the weight fraction of the silica sol added is 5 parts.

[0057] Comparative Example 3

[0058] The difference between this comparative example and Example 1 is only that, in this comparative example, no zirconium acetate is added, the weight fraction of the silica sol added is 3.75 parts, and the weight fraction of the styrene-acrylic emulsion added is 1.25 parts.

[0059] Comparative Example 4

[0060] The difference between this comparative example and Example 1 is only that, in this comparative example, no tungsten carbide is added.

[0061] Twelve magnesia-carbon bricks (from Tangshan Caofeidian District Energy-Saving Refractory Materials Co., Ltd., with the mass fraction of magnesia in the magnesia-carbon bricks ≥ 85% and the mass fraction of carbon ≥ 5%) were numbered 1-12 in sequence. The antioxidant coatings prepared in Examples 1-8 and Comparative Examples 1-4 were evenly coated onto the surfaces of each magnesia-carbon brick in the numbered order to form a coating layer with a thickness of 1 mm. The coated magnesia-carbon bricks were placed in a heating furnace and heated to 1400 °C at a heating rate of 5 °C / min in an air atmosphere (gas flow rate: 4 L / min), held for 2 h, and then naturally cooled to room temperature. Samples were taken, the coating layers on the surfaces of each magnesia-carbon brick were removed, and the thickness of the oxidation and decarburization layer of each magnesia-carbon brick was measured using a metallographic microscope. The measurement results are shown in Table 1 below.

[0062] Table 1 Measurement results of the thickness of the oxidation and decarburization layer

[0063]

[0064] The comparison between Example 1 and Comparative Examples 1-3 shows that the synergy of silica sol, styrene-acrylic emulsion, and zirconium acetate can significantly reduce the thickness of the oxidation and decarburization layer of magnesia-carbon bricks and improve the antioxidant ability of magnesia-carbon bricks. The comparison between Example 1 and Comparative Example 4 shows that the addition of tungsten carbide is beneficial to improving the antioxidant ability of magnesia-carbon bricks.

[0065] The comparison between Example 2 and Example 3 shows that when the particle size of silica sol ≤ 30 nm, the thickness of the oxidation and decarburization layer of magnesia-carbon bricks can be further reduced. The comparison between Example 3 and Example 4 shows that when the silica sol is cationic silica sol, it helps to further improve the antioxidant ability of magnesia-carbon bricks.

[0066] The comparison between Example 4 and Examples 5-8 shows that by doping zinc in tungsten carbide, the thickness of the oxidation and decarburization layer of magnesia-carbon bricks can be further reduced. The comparison between Examples 7-8 and Examples 5-6 shows that the optimal mass ratio of zinc powder to tungsten carbide is 1:9 - 3:7.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An antioxidant coating for ladle magnesia-carbon bricks, characterized in that, The raw materials include the following components in parts by weight: 30-50 parts of magnesite, 20-30 parts of alumina, 10-20 parts of tungsten carbide, 5-10 parts of binder, 5-15 parts of clay, and 5-15 parts of borate glass; The binder is composed of silica sol, styrene-acrylic emulsion and zirconium acetate mixed in a mass ratio of 3-8:1:

1.

2. The antioxidant coating for ladle magnesia-carbon bricks according to claim 1, wherein The particle size of the silica sol is ≤30 nm.

3. The antioxidant coating for ladle magnesia-carbon bricks according to claim 2, wherein, The silica sol is cationic silica sol.

4. An antioxidant coating for ladle magnesia-carbon bricks according to claim 1, characterized in that, The tungsten carbide is zinc-doped tungsten carbide, and the preparation method of the zinc-doped tungsten carbide is: mixing zinc powder and tungsten carbide evenly, vacuum sintering, cooling, crushing and grinding to obtain the zinc-doped tungsten carbide.

5. An antioxidant coating for ladle magnesia-carbon bricks according to claim 4, characterized in that, The mass ratio of the zinc powder to the tungsten carbide is 1:9-3:

7.

6. The antioxidant coating for ladle magnesia-carbon bricks according to claim 1, characterized in that, The particle sizes of the magnesite, alumina and tungsten carbide are each independently 45-75 μm.

7. The antioxidant coating for ladle magnesia-carbon bricks according to claim 6, characterized in that, The particle size of the magnesite is 63-75 μm; and / or The particle size of the alumina is 53-63 μm; and / or The particle size of the tungsten carbide is 45-53 μm.

8. An antioxidant coating for ladle magnesia-carbon bricks according to claim 1, characterized in that, The clay is one or more of Guangxi white clay, montmorillonite and bentonite.

9. A preparation method of an antioxidant coating for a ladle magnesia-carbon brick according to any one of claims 1-8, characterized in that, It includes the following steps: Mixing the raw materials evenly to obtain an antioxidant coating.

10. Application of the antioxidant coating for ladle magnesia-carbon bricks according to any one of claims 1-8 or the antioxidant coating obtained by the preparation method according to claim 9 in the antioxidant of ladle magnesia-carbon bricks.

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