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CN-122010531-A - Long nozzle lining material for cord steel casting

CN122010531ACN 122010531 ACN122010531 ACN 122010531ACN-122010531-A

Abstract

The invention belongs to the technical field of refractory materials for metallurgical continuous casting, and discloses a long nozzle lining material for casting cord steel, which comprises, by weight, 5-10 parts of magnesia, 70-90 parts of quartz, 2-5 parts of crystalline flake graphite, 3-4 parts of silicon carbide powder and 8-12 parts of thermosetting phenolic resin. The invention takes quartz as a main body, provides good high-temperature volume stability and erosion resistance, improves slag erosion resistance by introducing magnesia, can slightly expand forsterite phase formed by magnesia and quartz at high temperature, seals air holes and improves permeation resistance, constructs a high-efficiency heat conduction and oxidation resistance network by crystalline flake graphite and silicon carbide, takes thermosetting phenolic resin as a binding agent, provides excellent initial strength and carbonization strength, and improves thermal shock stability, high-temperature strength and molten steel permeation resistance of a long nozzle body by specific raw material selection and particle grading, thereby being particularly suitable for casting high-quality steel types such as cord steel under severe conditions.

Inventors

  • LI CHUANSHAN

Assignees

  • 青岛华冶高温材料有限公司

Dates

Publication Date
20260512
Application Date
20260120

Claims (9)

  1. 1. The long nozzle lining material for casting the cord steel is characterized by comprising the following components in parts by mass: 5-10 parts of magnesia, 70-90 Parts of quartz, 2-5 Parts of flake graphite, 3-4 Parts of silicon carbide powder, 8-12 Parts of thermosetting phenolic resin.
  2. 2. A long nozzle liner material for cord steel casting as set forth in claim 1, wherein: the mass content of magnesium oxide in the magnesia is not less than 90%; the grain composition of the magnesia comprises 20% -35% of coarse grains of 1 mm-0.5 mm, 25% -40% of medium grains of 0.5 mm-0.074 mm and 30% -45% of fine powder smaller than 0.074 mm.
  3. 3. A long nozzle lining material for casting a cord steel as set forth in claim 1, wherein said quartz is natural quartz or high quality pulse quartz with a crystal integrity and a purity of not less than 99.2% and an average particle size distribution of 10 μm to 50. Mu.m.
  4. 4. The long nozzle lining material for casting cord steel as claimed in claim 1, wherein the fixed carbon content of the crystalline flake graphite is not less than 98%, and the crystalline flake size is 80-200 meshes.
  5. 5. A long nozzle liner material for cord steel casting as set forth in claim 1, wherein: The silicon carbide powder is black or green silicon carbide, and the SiC content of the silicon carbide powder is not less than 97%; the silicon carbide powder has the particle size distribution that more than 95% of particles pass through a 400-mesh standard sieve, and the median particle diameter D50 is in the range of 15-30 mu m.
  6. 6. A long nozzle lining material for casting cord steel, as set forth in claim 1, characterized in that the thermosetting phenolic resin is an alcohol-soluble or water-soluble phenolic resin, the viscosity of which is 500 mPa.s-2000 mPa.s at 25 ℃, the solid content is 75% -85%, and the free phenol content is lower than 5%.
  7. 7. A long nozzle lining material for casting cord steel, as set forth in claim 1, further comprising 0.5-2 parts of an antioxidant, wherein the antioxidant is one or more of metal silicon powder, metal aluminum powder, zirconium boride or boron carbide.
  8. 8. A long nozzle lining material for casting cord steel according to claim 1, further comprising 0.1-1 part of a sintering aid, wherein the sintering aid is one or more of Suzhou soil, spodumene or titanium dioxide.
  9. 9. A long nozzle lining material for casting of a cord steel as claimed in any one of claims 1 to 8, wherein said long nozzle lining material is prepared by the steps of: step 1, weighing magnesia, quartz, crystalline flake graphite, silicon carbide powder, and optional antioxidants and sintering aids according to the proportion, and placing the materials in mixing equipment for dry mixing for 5-15 minutes until the materials are uniformly mixed; And step 2, adding the thermosetting phenolic resin with the formula amount into the dry blend obtained in the step 1, and wet-mixing for 20-40 minutes to obtain the plastic pug.

Description

Long nozzle lining material for cord steel casting Technical Field The invention relates to the technical field of refractory materials for metallurgical continuous casting, in particular to a long nozzle lining material for casting cord steel. Background The long nozzle is used as a key refractory component for connecting a ladle and a tundish in the continuous casting process, and the performance of the long nozzle directly influences the purity of molten steel, the stability of the continuous casting process and the quality of a final product. Particularly, when casting a steel grade such as a cord steel, which has extremely high requirements on the content, morphology and distribution of nonmetallic inclusions, the long nozzle must have excellent high-temperature strength, thermal shock resistance, molten steel and slag erosion resistance and permeation resistance, so as to prevent inclusions such as Al 2O3 from blocking the nozzle, prevent secondary oxidation of the molten steel, and control nitrogen-hydrogen compatibilization. Continuous casting is a core process in modern steel production, and long water gap is an important functional element for protecting steel flow and realizing non-oxidation casting in the process. The device is arranged below a drain port at the bottom of the ladle and is immersed into molten steel in the intermediate tank to form a closed channel, so that the molten steel is effectively prevented from being contacted with air, secondary oxidization and splashing are reduced, and meanwhile, the device is also beneficial to controlling heat loss and slag entrainment of the molten steel. With the continuous improvement of the requirements of the steel industry on the quality of products, especially high-end special steels such as cord steel, bearing steel, steel for tire meridian, and the like, the types, the sizes, the numbers and the forms of inclusions in the steel are controlled to a very severe degree. The cord steel is mainly used for manufacturing the cord of the automobile tire, and is required to have extremely high strength, toughness and fatigue life, and any tiny nonmetallic inclusion can cause the cord to break during drawing or fail early in service. Therefore, in casting the cord steel, there is an unprecedented high performance requirement for refractory materials for continuous casting, particularly long nozzle, 1. In the continuous casting process, the long nozzle is subjected to abrupt temperature change from room temperature to 1600 ℃ or more, especially in operations such as casting, ladle changing, etc. The insufficient thermal shock resistance can cause cracks and even cracking in the material, so that molten steel is infiltrated or air is invaded, and inclusions are increased or a water gap is blocked, and 2, the molten steel flowing at high speed can continuously scour and erode the inner wall of the long water gap. The lining material is worn and peeled off due to insufficient high-temperature strength, and peeled refractory material particles enter molten steel to become foreign impurities, so that the cleanliness of the steel is seriously affected, and 3, the long nozzle lining material needs to resist chemical erosion and physical infiltration of the molten steel and covering slag thereof. In particular, the cord steel often contains higher manganese and other alloying elements, which react with the refractory material and accelerate corrosion. Meanwhile, molten steel, particularly aluminum, silicon and other elements in the molten steel easily permeate into pores of a refractory material and react with material components to generate low-melting substances or new phases, so that the material structure is loose, the strength is reduced, and even an argon blowing channel is blocked, and 4, a modern long water gap is usually provided with an argon blowing function, and oxides such as Al 2O3 and the like are further prevented from adhering and gathering by forming an argon film on the surface of the inner wall. This requires that the seal structure for connection with the metal parts such as the argon blowing nozzle must be reliable for a long period of time, ensure that argon does not leak, and that the lining material itself is stable in performance in an argon atmosphere. At present, the common long nozzle lining materials in the market mainly comprise two major types of aluminum carbon and magnesium carbon, and although the two major types of long nozzle lining materials have advantages, the two major types of long nozzle lining materials are difficult to meet the extreme working condition requirements of continuous casting of the cord steel. The aluminum-carbon material has good thermal shock resistance, but has relatively insufficient high-temperature strength and is easy to react with elements such as manganese in the cord steel, and the magnesium-carbon material has good erosion resistance, but has poor thermal shock resistance and is easy to gene