Submerged nozzle lining material for continuous casting of rare earth steel and preparation method of submerged nozzle lining material

Abstract

The invention discloses a submerged nozzle lining material for rare earth steel continuous casting and a preparation method thereof, and relates to the field of refractory materials. The high-strength wear-resistant ceramic material comprises the following components in percentage by weight: 40-65 wt% of fused white corundum, 8-20 wt% of quartz, 15-25 wt% of crystalline flake graphite, 1-2 wt% of metal silicon powder, 2-4 wt% of ferro-silicon nitride powder, 0.5-1 wt% of boron carbide powder and 8-12 wt% of thermosetting phenolic resin. The method has the beneficial effects that the raw materials are processed through the processes of mixing, drying and the like to prepare the pug, the pug is used for manufacturing the submersed nozzle lining, the submersed nozzle using the lining is used for rare earth steel pouring, the nodulation problem of an inner hole of the nozzle is remarkably relieved, the content of inclusions in molten steel is reduced, the quality of steel billets is improved, and meanwhile the production cost is reduced. And the service life of the submersed nozzle is prolonged, so that the submersed nozzle is more suitable for production of rare earth steel protective pouring.

Description

Technical Field

[0001] The present invention relates to the field of refractory materials, and specifically relates to an immersion nozzle lining material for continuous casting of rare earth steel and a preparation method thereof. Background Art

[0002] During the continuous casting production process, the immersion nozzle is an important functional refractory material to ensure efficient continuous casting, which plays roles such as controlling the flow rate and flow field of molten steel and preventing secondary oxidation of molten steel. Rare earth elements have high chemical activity and are prone to react with elements such as oxygen and sulfur in molten steel to form inclusions such as rare earth oxides and rare earth sulfides. These inclusions have relatively high melting points and are easy to accumulate and adhere to the inner wall of the immersion nozzle, forming nodular substances. In addition, when rare earth is added to molten steel, the viscosity increases, the flow resistance of molten steel is large, and during the casting process, it is easy to stay in local areas of the inner hole of the nozzle, which will also increase nodulation.

[0003] The currently used traditional immersion nozzle lining has a high apparent porosity, or due to poor antioxidant performance and high-temperature strength, a rough and porous structure is formed on the inner hole surface, which is easy to form nodules, affecting the normal flow pattern of molten steel in the mold, resulting in a change in the flow field and affecting the quality of the cast slab. The nodular substances fall off into the molten steel, forming inclusions with larger sizes, reducing the purity of molten steel. Nodulation will also shorten the service life of the nozzle and increase production costs. Therefore, there is an urgent need to develop a new lining material with both high density, excellent antioxidant properties and erosion resistance. Summary of the Invention

[0004] The purpose of the present invention is to provide an immersion nozzle lining material for continuous casting of rare earth steel and a preparation method thereof in view of the deficiencies and defects in the prior art. By optimizing the material components and ratios, the antioxidant property, erosion resistance and surface smoothness of the lining are significantly improved, thereby effectively inhibiting the nodulation phenomenon during the pouring of rare earth steel, prolonging the service life of the nozzle and improving the quality of the cast slab.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: an immersion nozzle lining material for continuous casting of rare earth steel and a preparation method thereof, by weight percentage, includes the following components: fused white corundum 40 - 65wt%, quartz 8 - 20wt%, flake graphite 15 - 25wt%, metallic silicon powder 1 - 2wt%, ferrosilicon nitride powder 2 - 4wt%, boron carbide powder 0.5 - 1wt%, thermosetting phenolic resin 8 - 12wt%.

[0006] Further, the particle size of the ferrosilicon nitride powder is 200 - 400 mesh.

[0007] Further, the residual carbon content of the thermosetting phenolic resin is ≥30%.

[0008] An immersion nozzle lining material for continuous casting of rare earth steel and a preparation method thereof, which includes the following preparation method: S1. Weigh each raw material according to the ratio, mix them evenly, and then make the mud through kneading and drying processes. S2. Press the mud into shape and obtain the refractory lining blank of the submerged entry nozzle through solidification treatment. S3. After the mud is pressed into shape and solidified, it is sintered at 1400 - 1600 °C for 4 - 8 hours and then processed to the required size.

[0009] After adopting the above technical solution, the beneficial effects of the present invention are as follows: The raw materials are processed through kneading, drying and other processes to make the mud, which is used to make the refractory lining of the submerged entry nozzle. The submerged entry nozzle using this lining is used for the casting of rare earth steel, significantly reducing the nodulation problem of the inner hole of the nozzle and reducing the content of inclusions in the molten steel. While improving the quality of the steel billet, the service life of the submerged entry nozzle is increased, making it more suitable for the production of protective casting of rare earth steel. Description of the Drawings

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0011] Figure 1 It is the surface diagram of the inner hole of the submerged entry nozzle using this lining material in the present invention (without obvious nodules, smooth and flat). Figure 2 It is the inner hole surface of the nozzle with the traditional lining material (a large number of nodules and uneven structures can be seen). Detailed Embodiments

[0012] Refer to Figure 1 - Figure 2 As shown, the technical solution adopted in this detailed embodiment is as follows: By weight percentage, it includes the following components: fused white corundum 40 - 65 wt%, quartz 8 - 20 wt%, flake graphite 15 - 25 wt%, metallic silicon powder 1 - 2 wt%, ferrosilicon nitride powder 2 - 4 wt%, boron carbide powder 0.5 - 1 wt%, and thermosetting phenolic resin 8 - 12 wt%. The particle size of the ferrosilicon nitride powder is 200 - 400 mesh. The residual carbon content of the thermosetting phenolic resin ≥ 30%. The introduction of the ferrosilicon nitride powder significantly enhances the oxidation resistance and high-temperature stability of the material. The synergistic effect of the boron carbide powder and the metallic silicon powder can reduce the sintering temperature and improve the density, while the thermosetting phenolic resin as a binder ensures the structural strength of the material after forming.

[0013] A refractory lining material for a submerged entry nozzle used in continuous casting of rare earth steel and its preparation method, which includes the following preparation method: S1. Weigh each raw material according to the ratio, mix them evenly, and then make the mud material through kneading and drying processes. S2. Press the mud material into shape and obtain the immersed nozzle lining blank after solidification treatment. S3. After the mud material is pressed into shape and solidified, sinter it at 1400 - 1600 °C for 4 - 8 hours, and then process it to the required size. Example

[0014] Prepare the lining material according to the following ratio: fused white corundum 55 wt%, quartz 10 wt%, flake graphite 20 wt%, metallic silicon powder 1.5 wt%, ferrosilicon nitride powder 3 wt%, boron carbide powder 0.5 wt%, thermosetting phenolic resin 10 wt%.

[0015] The preparation process is carried out according to the above - mentioned preparation method. The apparent porosity of the obtained nozzle lining is 10.5%, and the high - temperature strength reaches 28 MPa. When applied to the casting of rare - earth steel, the nodule formation is reduced by 65%, and the service life is extended by 45%.

[0016] As mentioned above, it is only used to illustrate the technical solution of the present invention rather than to limit it. Any other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, shall be covered by the scope of the claims of the present invention.

Claims

1. An immersion nozzle lining material for continuous casting of rare earth steel, characterized in that: It comprises the following components by weight percentage: fused white corundum 40-65 wt%, quartz 8-20 wt%, flake graphite 15-25 wt%, metallic silicon powder 1-2 wt%, ferrosilicon nitride powder 2-4 wt%, boron carbide powder 0.5-1 wt%, and thermosetting phenolic resin 8-12 wt%.

2. The submerged nozzle lining material for continuous casting of rare earth steel according to claim 1, characterized in that: The ferrosilicon nitride powder has a particle size of 200-400 mesh.

3. The submerged nozzle lining material for continuous casting of rare earth steel according to claim 1, wherein: The residual carbon content of the thermosetting phenolic resin is ≥ 30%.

4. An immersion nozzle lining material for rare earth steel continuous casting and its preparation method, characterized in that: It includes the following preparation method: S1, Weigh each raw material according to the ratio, and after mixing evenly, make it into a mud through kneading and drying processes; S2, Press the mud into shape, and obtain the refractory preform for submerged nozzle after curing treatment; S3, After the mud is pressed into shape and cured, sinter it at 1400-1600 °C for 4-8 hours, and process it to the required size.

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