Inner hole anti-blocking coating of submersed nozzle for rare earth steel and submersed nozzle

Abstract

The invention discloses an inner hole anti-blocking coating of a submersed nozzle for rare earth steel and the submersed nozzle. The inner hole anti-blocking coating of the submersed nozzle for the rare earth steel comprises yttria-stabilized zirconia, cerium oxide and lanthanum oxide. The mass ratio of yttria-stabilized zirconia to cerium oxide to lanthanum oxide is (90-95): (1-9): (1-9). According to the method, distillation of the inner hole body of the submersed nozzle in the rare earth steel continuous casting process is reduced, the service life of the submersed nozzle is prolonged, the number of continuous casting furnaces of a tundish is increased, and the castability of rare earth steel continuous casting is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of coating materials, and in particular to an anti-clogging coating for the inner hole of an immersion nozzle for rare earth steel and an immersion nozzle. Background Art

[0002] Rare earth is usually added to molten steel as an alloying element to refine the diameter and number of inclusions, purify the molten steel, and improve the performance of the steel. In order to improve the yield of rare earth alloys, it is necessary to control the oxygen and sulfur content of the molten steel. Adding rare earth alloys in RH can avoid oxidation of rare earth by air and slag, thereby reducing the content of rare earth inclusions in steel and improving the castability of molten steel.

[0003] Rare earth elements (RE) have low melting points and are easily oxidized. In the process of steel smelting, rare earths are very likely to react with slag, refractory materials and air, and the actual recovery rate of rare earths is generally low. Rare earth elements are oxidized in molten steel to form high-melting rare earth oxides (RE2O3) and oxysulfides (RE2O2S). Rare earth oxides react with Al2O3-C refractory materials to produce rare earth aluminates (REAlO3), rare earth silicates (RESiO4) and high-viscosity aluminum-rich glass phases. These reactions lead to irregular surfaces in the inner hole of the nozzle and the plug rod head, causing inclusions to gather here; therefore, it is easy to cause clogging of the submerged nozzle and nodules on the plug rod head, which has an adverse effect on the continuous casting process.

[0004] Chinese patent publication number CN114773045A discloses a magnesium-silicon coating for continuous casting nozzles, which solves the problem of nozzle blockage during the continuous casting of rare earth steel; the coating components are magnesium-silicon oxide and rare earth oxide, and the mass ratio of magnesium-silicon oxide to rare earth oxide is 84.54-91:1.98-10; the magnesium-silicon oxide is mainly 2MgO·SiO2 and contains a trace amount of MgO; the coating is applied to the nozzle, which reduces the frequency of nozzle replacement by an average of more than 50%, but 2MgO·SiO2 has a low melting point, a large thermal expansion coefficient, and is easy to oxygenate molten steel, which is not conducive to application in large-scale production sites. Chinese patent publication number CN114309571A discloses a method and device for inhibiting nozzle blockage during the continuous casting of rare earth steel. By adding a pulse current generating device, nozzle heating, nozzle argon blowing device, improving the nozzle material and other technical means, the electrochemical reaction between the molten steel and the nozzle is reduced, the wettability of the rare earth steel liquid and the nozzle is improved, the flow state of the molten steel is changed, and the anti-blocking effect of the nozzle is improved; however, the device has high cost and weak stability, which is not conducive to application in large-scale industrial production.

[0005] In view of the above situation, it is urgent to develop a coating that can reduce the distillation of the inner hole of the submerged nozzle for rare earth steel, which can effectively reduce the distillation of the inner hole of the submerged nozzle during the continuous casting of rare earth steel, increase the life of the submerged nozzle and the number of continuous casting furnaces of the tundish, and ensure the castability of the continuous casting of rare earth steel. Summary of the invention

[0006] In view of the problem in the prior art that the inner pores of an immersion nozzle are prone to distillation during the continuous casting of rare earth steel, the purpose of the present invention is to provide an anti-clogging coating for the inner pores of an immersion nozzle for rare earth steel and an immersion nozzle, which can reduce the reaction of Al2O3 and SiO2 in the inner pores of the nozzle with RE in the molten steel to generate high-melting-point RE2O3, RESiO4 and REAlO3, reduce the distillation of the inner pores of the immersion nozzle during the continuous casting of rare earth steel, increase the service life of the immersion nozzle and the number of continuous casting furnaces for the tundish, and ensure the castability of the continuous casting of rare earth steel.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides an anti-clogging coating for the inner hole of an immersion nozzle for rare earth steel, the components of which include yttria-stabilized zirconia, cerium oxide and lanthanum oxide;

[0009] The mass ratio of the yttria-stabilized zirconia, cerium oxide and lanthanum oxide is 90-95:1-9:1-9.

[0010] Preferably, the stabilizer of the yttria-stabilized zirconia is yttria material; the added amount of the yttria material is 3% to 6% of the mass of the zirconia.

[0011] Preferably, Y2O3 in the yttrium oxide material is ≥99.9%.

[0012] Preferably, the thickness of the anti-clogging coating on the inner hole of the immersion nozzle for rare earth steel is 8 to 15 mm.

[0013] The second aspect of the present invention provides an immersion nozzle, comprising a nozzle body, a slag line arranged on the nozzle body and an inner hole body arranged in the nozzle body, wherein the inner hole body is sprayed with an anti-clogging coating for the inner hole of the immersion nozzle for rare earth steel as described in the first aspect of the present invention.

[0014] Preferably, the material of the nozzle body is aluminum carbon; the components of the aluminum carbon are: the weight percentage of Al2O3 is 45-70%, the weight percentage of C is 20-30%, and the remainder is impurities.

[0015] Preferably, the slag line is made of zirconium carbon; the components of the zirconium carbon are: the weight percentage of ZrO2 is 80-90%, the weight percentage of C is 10-20%, and the remainder is impurities.

[0016] Preferably, the material of the inner porous body includes aluminum silicate; the components of the aluminum silicate are: the weight percentage of Al2O3 is 85-90%, the weight percentage of SiO2 is 5-10%, and the balance is impurities.

[0017] Preferably, the submerged nozzle is applied to the continuous casting process of Ce-La treated steel, the thickness of the nodule layer in the inner hole is less than or equal to 5 mm, and the submerged nozzle is replaced every 8 to 9 furnaces on average.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention can prolong the service life of the submerged nozzle and increase the number of tundish continuous casting furnaces;

[0020] 2. The present invention can reduce the blockage of the immersion nozzle for rare earth steel treatment, improve the problem of large fluctuation of the crystallizer liquid level, and improve the continuous casting castability;

[0021] 3. The submerged nozzle of the present invention can improve the recovery rate of rare earth elements in molten steel;

[0022] 4. The present invention sprays an anti-clogging coating on the inner hole of the immersion nozzle to reduce the reaction of Al2O3 and SiO2 in the refractory material in the inner hole of the nozzle with RE in the molten steel to generate high-melting point RE2O3, RESiO4 and REAlO3, thereby improving the problems of nozzle blockage and large fluctuation of the crystallizer liquid level when pouring rare earth steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0024] Figure 1 It is a structural schematic diagram of the submerged nozzle of the present invention;

[0025] Figure 2 Schematic diagram of the distillation in the inner hole of the submerged nozzle in the comparative example, (a) is a schematic diagram of the distillation in the inner hole of the submerged nozzle (the M area is green), and (b) is a SEM image of the distillate;

[0026] Figure 3 Schematic diagram of distillation in the inner hole of the submerged nozzle of Example 2, (a) is a schematic diagram of distillation in the inner hole of the submerged nozzle (N area is grayish white), and (b) is a SEM image of the distillate. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form.

[0028] The invention provides an anti-clogging coating for the inner hole of an immersion nozzle for rare earth steel, the components of which include yttria-stabilized zirconia, cerium oxide and lanthanum oxide; the mass ratio of yttria-stabilized zirconia, cerium oxide and lanthanum oxide is 90-95:1-9:1-9.

[0029] In the components of the above-mentioned rare earth steel submerged nozzle inner hole anti-clogging coating, the stabilizer of yttria-stabilized zirconia is yttria material; the added amount of yttria material is 3% to 6% of the mass of zirconia; wherein Y2O3 in the yttria material is ≥99.9%.

[0030] The thickness of the anti-clogging coating on the inner hole of the immersion nozzle for rare earth steel is 9 to 15 mm.

[0031] The above-mentioned anti-clogging coating for the inner hole of the submerged nozzle for rare earth steel is composed of yttria-stabilized zirconia (YSZ) and rare earth oxide (REOx) in a certain proportion, and yttria-stabilized zirconia (YSZ) and rare earth oxide (REOx) are sprayed on the inner hole body of the submerged nozzle using plasma spraying technology to form a YSZ-REOx coating; the rare earth elements in the rare earth steel mentioned in the present invention are cerium (Ce) and lanthanum (La), and the anti-clogging mechanism is that the coating material YSZ-REOx of the inner hole body of the submerged nozzle can effectively inhibit the reaction of rare earth elements Ce and La with Al2O3 and SiO2 in the inner hole body of the submerged nozzle, slow down the formation of rare earth aluminates and rare earth silicates, and reduce nozzle nodules.

[0032] The anti-clogging coating for the inner hole of the submerged nozzle for rare earth steel has excellent corrosion resistance and spalling resistance. ZrO2 alone will undergo crystal transformation at high temperatures to cause thermal expansion. The addition of yttrium oxide (Y2O3) can greatly increase the temperature range in which ZrO2 can exist stably in the cubic phase and prevent the crystal transformation of ZrO2. On the other hand, the presence of rare earth oxides Ce2O3 and La2O3 can inhibit reactions ① to ④.

[0033] [Ce]+Al2O3(s) = CeAlO3(s)+[Al] ①

[0034] [Ce]+CeAlO3(s) = Ce2O3(s)+[Al] ②

[0035] [La]+Al2O3(s) = LaAlO3(s)+[Al] ③

[0036] [La]+LaAlO3(s) = La2O3(s)+[Al] ④

[0037] Combination Figure 1 As shown, the present invention also provides an immersion nozzle, including a nozzle body 1, a slag line 2 arranged on the nozzle body 1 and an inner hole body 3 arranged in the nozzle body 1, and the inner hole body 3 is sprayed with the above-mentioned rare earth steel immersion nozzle inner hole anti-clogging coating.

[0038] The material of the nozzle body 1 is aluminum carbon (i.e., Al2O3-C); the components of aluminum carbon are: the weight percentage of Al2O3 is 45-70%, the weight percentage of C is 20-30%, and the balance is impurities. In a further preferred embodiment, the components of aluminum carbon are: the weight percentage of Al2O3 is 62%, the weight percentage of C is 22%, and the balance is impurities.

[0039] The material of the slag line 2 is zirconium carbon (i.e., ZrO2-C); the composition of zirconium carbon is: the weight percentage of ZrO2 is 80-90%, the weight percentage of C is 10-20%, and the balance is impurities. In a further preferred embodiment, the composition of zirconium carbon is: the weight percentage of ZrO2 is 76%, the weight percentage of C is 16%, and the balance is impurities.

[0040] The material of the inner porous body 3 includes aluminum silicate (i.e., Al2O3 and SiO2); the components of aluminum silicate are: the weight percentage of Al2O3 is 85-90%, the weight percentage of SiO2 is 5-10%, and the balance is impurities. In a further preferred embodiment, the components of aluminum silicate are: the weight percentage of Al2O3 is 87%, the weight percentage of SiO2 is 8%, and the balance is impurities.

[0041] The following is a further introduction to an anti-clogging coating for the inner hole of an immersion nozzle for rare earth steel and an immersion nozzle with specific examples.

[0042] Comparative Example

[0043] In this comparative example, the nozzle body of the submerged nozzle is made of aluminum carbon, the chemical composition weight percentage of Al2O3 is 62%, the chemical composition weight percentage of C is 22%, and the balance is impurities; the slag line is made of zirconium carbon, the chemical composition weight percentage of ZrO2 is 76%, the chemical composition weight percentage of C is 16%, and the balance is impurities; the inner pore body is made of aluminum silicon, the chemical composition weight percentage of Al2O3 is 87%, the chemical composition weight percentage of SiO2 is 8%, and the balance is impurities. Among them, the addition amount of yttrium oxide material is 4% of the mass of zirconium oxide.

[0044] In this comparative example, the anti-clogging coating is not sprayed on the inner hole of the submerged nozzle.

[0045] The submerged nozzle is used in the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 10 mm, and the submerged nozzle is replaced every 4.7 furnaces on average.

[0046] Nodule layer thickness = (inner hole diameter after spraying - inner hole diameter after use) / 2

[0047] The nodules in the nozzles of this comparative example and their microstructure and energy spectrum are shown in Figure 2. Figure 2 As shown; Figure 2The color of the M area in (a) is green, that is, the nodules in the nozzle inner hole are green. Combined with the surface scan, it can be seen that it is caused by the presence of rare earth oxides; combined with the energy spectrum chart of the distillate in Table 1, it can be seen that the Ce element accounts for 14.81% and the La element accounts for 7.71% in weight percentage. This shows that the recovery rate of rare earth elements in molten steel is not high, and they react with the materials in the nozzle inner hole to form rare earth oxides.

[0048] Table 1 Energy spectrum of distillate

[0049]

[0050] Example 1

[0051] The materials used for the nozzle body, slag line and inner hole of the rare earth steel immersion nozzle in this embodiment are the same as those in the comparative example. The amount of yttrium oxide material added is 3% of the mass of zirconium oxide, and Y2O3 in the yttrium oxide material is ≥99.9%.

[0052] The anti-clogging coating for the inner hole of the submerged nozzle for rare earth steel is prepared as follows:

[0053] Yttria-stabilized zirconia (YSZ), cerium oxide (CeO2) and lanthanum oxide (La2O3) are uniformly mixed in a high-speed disperser to obtain a mixed powder;

[0054] The mass ratio of the mixed powder is YSZ:CeO2:La2O3=90:4:6;

[0055] The mixed powder is sprayed on the inner hole of the immersion nozzle by plasma spraying equipment to obtain an anti-clogging coating for the inner hole of the immersion nozzle for rare earth steel, and the coating thickness is 9mm. During the ion spraying process: the working gas is Ar and H2, and the powder feeding rate is 60g / min.

[0056] The submerged nozzle for rare earth steel in this embodiment is applied to the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 4 mm, and the submerged nozzle is replaced every 8.9 furnaces on average.

[0057] Example 2

[0058] The materials used for the nozzle body, slag line and inner hole of the rare earth steel immersion nozzle in this embodiment are the same as those in the comparative example. The amount of yttrium oxide material added is 4% of the mass of zirconium oxide, and Y2O3 in the yttrium oxide material is ≥99.9%.

[0059] The anti-clogging coating for the inner hole of the submerged nozzle for rare earth steel is prepared as follows:

[0060] Yttria-stabilized zirconia (YSZ), cerium oxide (CeO2) and lanthanum oxide (La2O3) are uniformly mixed in a high-speed disperser to obtain a mixed powder;

[0061] The mass ratio of the mixed powder is YSZ:CeO2:La2O3=93:4:3;

[0062] The mixed powder is sprayed on the inner hole of the submerged nozzle by plasma spraying equipment to obtain an anti-rare earth nodule coating with a coating thickness of 12 mm. During the ion spraying process: the working gas is Ar and H2, and the powder feeding rate is 60 g / min.

[0063] The submerged nozzle for rare earth steel in this embodiment is applied to the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 2 mm, and the submerged nozzle is replaced every 8.9 furnaces on average.

[0064] The nozzle inner hole nodules and their microstructure and energy spectrum of this embodiment are as follows: Figure 3 As shown, Figure 3 The color of the M area in (a) is grayish white, that is, the nodules in the inner hole of the nozzle are grayish white, and there is no obvious nodule. Combining the surface scan and the energy spectrum chart of the nodules in Table 2, it can be seen that the Ce element accounts for 7.4% by weight, and the La element is not detected. Compared with the comparative example, the nozzle nodule layer of this embodiment is thin, and the rare earth elements in the nodules are less.

[0065] Table 2 Energy spectrum of distillate

[0066]

[0067] Example 3

[0068] The materials used for the nozzle body, slag line and inner hole of the rare earth steel immersion nozzle in this embodiment are the same as those in the comparative example. The amount of yttrium oxide material added is 5% of the mass of zirconium oxide, and Y2O3 in the yttrium oxide material is ≥99.9%.

[0069] Yttria-stabilized zirconia (YSZ), cerium oxide (CeO2) and lanthanum oxide (La2O3) are uniformly mixed in a high-speed disperser to obtain a mixed powder;

[0070] The mass ratio of the mixed powder is YSZ:CeO2:La2O3=95:3:2;

[0071] The mixed powder is sprayed on the inner hole of the submerged nozzle by plasma spraying equipment to obtain an anti-rare earth nodule coating with a coating thickness of 12 mm. During the ion spraying process: the working gas is Ar and H2, and the powder feeding rate is 60 g / min.

[0072] The submerged nozzle for rare earth steel in this embodiment is applied to the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 3 mm, and the submerged nozzle is replaced every 8.3 furnaces on average.

[0073] Example 4

[0074] The materials used for the nozzle body, slag line and inner hole of the rare earth steel immersion nozzle in this embodiment are the same as those in the comparative example. The amount of yttrium oxide material added is 6% of the mass of zirconium oxide, and Y2O3 in the yttrium oxide material is ≥99.9%.

[0075] Yttria-stabilized zirconia (YSZ), cerium oxide (CeO2) and lanthanum oxide (La2O3) are uniformly mixed in a high-speed disperser to obtain a mixed powder;

[0076] The mass ratio of the mixed powder is YSZ:CeO2:La2O3=90:9:1;

[0077] The mixed powder is sprayed on the inner hole of the submerged nozzle by plasma spraying equipment to obtain an anti-rare earth nodule coating with a coating thickness of 15 mm. During the ion spraying process: the working gas is Ar and H2, and the powder feeding rate is 60 g / min.

[0078] The submerged nozzle for rare earth steel in this embodiment is applied to the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 4 mm, and the submerged nozzle is replaced once every 8.1 furnaces on average.

[0079] Example 5

[0080] The materials used for the nozzle body, slag line and inner hole of the rare earth steel immersion nozzle in this embodiment are the same as those in the comparative example. The amount of yttrium oxide material added is 4% of the mass of zirconium oxide, and Y2O3 in the yttrium oxide material is ≥99.9%.

[0081] Yttria-stabilized zirconia (YSZ), cerium oxide (CeO2) and lanthanum oxide (La2O3) are uniformly mixed in a high-speed disperser to obtain a mixed powder;

[0082] The mass ratio of the mixed powder is YSZ:CeO2:La2O3=90:1:9;

[0083] The mixed powder is sprayed on the inner hole of the submerged nozzle by plasma spraying equipment to obtain an anti-rare earth nodule coating with a coating thickness of 13 mm. During the ion spraying process: the working gas is Ar and H2, and the powder feeding rate is 60 g / min.

[0084] The submerged nozzle for rare earth steel in this embodiment is applied to the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 5 mm, and the submerged nozzle is replaced once every 9.0 furnaces on average.

[0085] Example 6

[0086] The materials used for the nozzle body, slag line and inner hole of the rare earth steel immersion nozzle in this embodiment are the same as those in the comparative example. The amount of yttrium oxide material added is 4% of the mass of zirconium oxide, and Y2O3 in the yttrium oxide material is ≥99.9%.

[0087] Yttria-stabilized zirconia (YSZ), cerium oxide (CeO2) and lanthanum oxide (La2O3) are uniformly mixed in a high-speed disperser to obtain a mixed powder;

[0088] The mass ratio of the mixed powder is YSZ:CeO2:La2O3=90:9:1;

[0089] The mixed powder is sprayed on the inner hole of the submerged nozzle by plasma spraying equipment to obtain an anti-rare earth nodule coating with a coating thickness of 9 mm. During the ion spraying process: the working gas is Ar and H2, and the powder feeding rate is 60 g / min.

[0090] The submerged nozzle for rare earth steel in this embodiment is applied to the continuous casting process of Ce-La treated steel. The thickness of the nodule layer in the inner hole is 4 mm, and the submerged nozzle is replaced every 8.7 furnaces on average.

[0091] In summary, the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. An anti-clogging coating for the inner hole of an immersion nozzle for rare earth steel, characterized in that: Its components include yttria-stabilized zirconium oxide, cerium oxide, and lanthanum oxide; The mass ratio of the yttria-stabilized zirconia, cerium oxide and lanthanum oxide is 90-95:1-9:1-9.

2. The anti-clogging coating for inner hole of immersion nozzle for rare earth steel according to claim 1 is characterized in that: The stabilizer of the yttria-stabilized zirconia is yttria material; the added amount of the yttria material is 3% to 6% of the mass of the zirconia.

3. The anti-clogging coating for inner hole of submerged nozzle for rare earth steel according to claim 2, characterized in that: The Y2O3 in the yttrium oxide material is ≥99.9%.

4. The anti-clogging coating for inner hole of submerged nozzle for rare earth steel according to claim 1, characterized in that: The thickness of the anti-clogging coating on the inner hole of the immersion nozzle for rare earth steel is 8 to 15 mm.

5. An immersion nozzle, comprising a nozzle body, a slag line arranged on the nozzle body and an inner hole body arranged in the nozzle body, characterized in that: The inner hole body is sprayed with the anti-clogging coating for the inner hole of the immersion nozzle for rare earth steel as described in any one of claims 1 to 4.

6. The submerged nozzle according to claim 5, characterized in that: The material of the nozzle body is aluminum carbon; the components of the aluminum carbon are: the weight percentage of Al2O3 is 45-70%, the weight percentage of C is 20-30%, and the balance is impurities.

7. The submerged nozzle according to claim 5, characterized in that: The material of the slag line is zirconium carbon; the components of the zirconium carbon are: the weight percentage of ZrO2 is 80-90%, the weight percentage of C is 10-20%, and the balance is impurities.

8. The submerged nozzle according to claim 5, characterized in that: The material of the inner pore body includes aluminum silicate; the components of the aluminum silicate are: the weight percentage of Al2O3 is 85-90%, the weight percentage of SiO2 is 5-10%, and the balance is impurities.

9. The submerged nozzle according to any one of claims 6 to 8, characterized in that: The submerged nozzle is applied to the continuous casting process of Ce-La treated steel, the thickness of the nodule layer in the inner hole is less than or equal to 5 mm, and the submerged nozzle is replaced once every 8 to 9 furnaces on average.

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