Production method of zirconia composite material sizing nozzle for tundish of steelmaking

Abstract

The application provides a production method of a sizing nozzle made of zirconia composite material for a steelmaking tundish, which comprises the following steps: granulating titanium nitride fine powder to obtain titanium nitride particles; mixing the titanium nitride fine powder, zirconia fine powder, titanium nitride particles and mixed powder with a binder; forming in a mold; drying the formed product; and heating the dried product in an inert atmosphere to obtain a desired product. The production method of the sizing nozzle made of zirconia composite material for the steelmaking tundish solves the problem of low firing yield of the sizing nozzle made of zirconia material due to the crystal type conversion of zirconia, and the problem of frequent nozzle burst in use. By introducing the titanium nitride fine powder, the sintering performance of the product is improved and the zirconia crystal type is stabilized by using the activity of the titanium nitride fine powder, so that a sizing nozzle with high strength, high melting point, high thermal stability and high corrosion resistance to metal and steel slag is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of refractory materials, and particularly relates to a production method of a sizing nozzle made of zirconia composite material for a tundish for steelmaking. BACKGROUND

[0002] With the continuous development and progress of steelmaking and continuous casting technology, in order to meet and adapt to the needs of new technologies and new processes of high-efficiency continuous casting, the material, preparation process and use technology of functional refractory materials for tundishes have been greatly promoted and updated. In the continuous casting production process, the sizing nozzle is an important functional refractory material for tundishes, and its service life plays a crucial role in the efficiency and stability of continuous casting. Therefore, in the preparation process of the sizing nozzle, the material selection and preparation process of the nozzle are key factors to improve its service life.

[0003] For example, small billets are generally cast by using a sizing nozzle. The main function of the sizing nozzle is to control the flow of molten steel. Whether the molten steel can flow uniformly and stably into the crystallizer through the sizing nozzle is the key to ensure the normal operation of continuous casting. Therefore, the sizing nozzle must have good corrosion resistance and thermal stability, and cannot be blocked, shed, cracked or expanded during use. With the development of high-efficiency continuous casting technology, higher performance and service life requirements are put forward for refractory materials for continuous casting, such as long-life tundishes. Long-life tundishes can reduce the labor intensity of workers by reducing the replacement of tundishes, and can also reduce the occurrence of production accidents. However, there are many factors that restrict the service life of tundishes in actual production, the most common of which is the phenomenon of tundish sizing nozzle clamping steel. The sizing nozzle clamping steel cannot be replaced, which reduces the service life of the tundish and increases the production cost. In severe cases, the sizing nozzle clamping steel can also cause the sizing nozzle to drill steel. At the same time, the sizing nozzle for tundishes is subjected to erosion and corrosion due to some chemical components in the molten steel, and is also subjected to sudden temperature changes and mechanical stresses, making the damage mechanism and form of the nozzle more complex. Therefore, in the preparation process of the sizing nozzle, the material selection, preparation process and microstructure of the nozzle are key factors to improve its service life.

[0004] The present steelmaking tundish sizing nozzle adopts high-temperature sintered product of zirconia material, and the content of zirconia is between 90-95%. The zirconia material sizing nozzle has low sintered product yield due to the crystal type conversion of zirconia, and the nozzle often explodes during use, which causes production safety accidents and affects steelmaking operation. In practical application, in addition to ZrO2, a small amount of stabilizer is also contained in the nozzle material, so in the use process, the impurity elements (manganese, silicon, magnesium, aluminum, etc.) in the molten steel react to generate multi-element low-melting oxides, and with the loss of the molten steel, the erosion and diffusion of the sizing nozzle are caused. Titanium nitride is a high-melting-point compound with a melting point of 2950℃, good wear resistance, Mohs hardness of 8-9, good stability, no reaction with iron, chromium, calcium, magnesium and other metals at high temperature, no reaction with acidic slag and alkaline slag in carbon monoxide and nitrogen atmosphere, good thermal conductivity and high thermal stability. At the same time, titanium nitride can stabilize the crystal type of zirconia at high temperature. Although the apparent porosity of the sizing nozzle modified by adding Al2O3-ZrO2 composite powder is reduced, the bulk density is increased, and the compressive strength is improved, but in the actual application process, the main reason for the damage of the nozzle is the explosion during use due to the poor thermal shock stability. Therefore, in order to solve the technical defects of the present technology, the present application uses the characteristics of high melting point, high strength and high stability of titanium nitride to prepare a sizing nozzle of titanium nitride-zirconia composite material. The method uses the effect of TiN on stabilizing ZrO2 to maintain the normal temperature tetragonal phase, and reduces the phase transition rate. At the same time, TiN and ZrO2 have good chemical compatibility, and will not react during sintering. A sizing nozzle with high melting point, high thermal stability and high resistance to erosion of metal and steel slag is prepared. By adding TiN, cubic TiN will appear during sintering, and TiN particles will be dispersed in ZrO2 crystals, and most of them will be located at the grain boundaries. The TiN particles at the grain boundaries produce "pinning" effect, hinder the diffusion of Zr 4+ O2 particles and the movement of grain boundaries, thereby inhibiting the growth of ZrO2 particles, improving the toughening effect and improving the fracture toughness. The titanium nitride-zirconia sizing nozzle can meet the requirements of high melting point, high thermal stability and high resistance to erosion of metal and steel slag for the tundish, and can also improve the product yield. Compared with the traditional ZrO2 sizing nozzle, the titanium nitride-zirconia composite material sizing nozzle has improved density and increased compressive strength, which greatly improves the thermal shock stability and anti-erosion performance of the nozzle, solves the problem of low sintered product yield of the zirconia material sizing nozzle due to the crystal type conversion of zirconia, and the frequent explosion of the nozzle during use, and has obvious economic benefits. SUMMARY

[0005] Therefore, the present application aims to provide a production method of a zirconia composite material sizing nozzle for steelmaking tundish, to solve the problems mentioned in the background art.

[0006] To achieve the above object, the technical scheme of the present application is as follows:

[0007] A production method of a zirconia composite material sizing nozzle for a tundish in steelmaking, comprising the following steps:

[0008] (1) Granulation of titanium nitride fine powder: titanium nitride fine powder is mixed with phenolic resin powder, anhydrous ethanol is added for mixing, and then pressure forming, drying, nitriding sintering, and crushing into titanium nitride particles are performed;

[0009] (2) Titanium nitride fine powder and zirconia fine powder are premixed according to a proportion to obtain a mixed powder, and the titanium nitride particles and the mixed powder are added to a mixing machine for dry mixing, and then a binder is added for secondary mixing, and the product is discharged;

[0010] (3) The material obtained in step (2) is added to a mold for forming, and the mold is removed;

[0011] (4) The product formed in step (3) is dried;

[0012] (5) The dried product in step (4) is placed in a furnace body, heated in an inert atmosphere, and cooled to obtain the desired product.

[0013] Further, in step (1), the titanium nitride particles include particles with a particle size of 0-1 mm and particles with a particle size of 1-2 mm.

[0014] Further, in step (2), the mass ratio of titanium nitride, zirconia, and binder is (40-90):(10-60):(3-6).

[0015] Further, in step (1), the titanium nitride fine powder has a titanium content of not less than 75%, a nitrogen content of not less than 18%, a carbon content of not more than 3%, and an oxygen content of not more than 2%.

[0016] Further, in step (2), the purity of the zirconia is not less than 94%, and the particle size is less than 320 mesh.

[0017] Further, the zirconia is unshaped monoclinic zirconia or stabilized zirconia; preferably, the stabilized zirconia stabilizer is calcium oxide or yttrium oxide.

[0018] Further, in step (1), the binder is one or both of thermosetting phenolic resin and thermoplastic phenolic resin.

[0019] Further, in step (2), the titanium nitride fine powder and the zirconia fine powder are premixed for 30 minutes, the titanium nitride particles and the mixed powder are dry mixed for 5 minutes, and the secondary mixing time is 15 minutes.

[0020] Further, in step (4), the drying temperature is 110-200 DEG C, and the drying time is 24h.

[0021] Further, in step (5), the inert atmosphere is nitrogen atmosphere or argon atmosphere, the heating temperature is 1400-1500 DEG C, and the heating time is 3-10h.

[0022] Compared with the prior art, the production method of the zirconia composite material sizing nozzle for a tundish has the following advantages:

[0023] The production method of the titanium nitride-zirconia composite material sizing nozzle solves the problem of low high-temperature firing yield of the zirconia material sizing nozzle due to the crystal type conversion of zirconia, and the problem of frequent nozzle burst in use, by introducing titanium nitride fine powder, using the activity of the titanium nitride fine powder, improving the sintering performance of the product, and stabilizing the zirconia crystal type, so that a sizing nozzle with high strength, high melting point, high thermal stability, and high corrosion resistance to metals and steel slag is obtained. DETAILED DESCRIPTION

[0024] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0025] The present application will be described in detail below with reference to the embodiments.

[0026] Titanium nitride particle preparation example

[0027] 1) The raw materials are weighed according to the following mass fraction: 80-90 parts of titanium nitride fine powder with a particle size of 100-600 mesh, and 3-15 parts of phenolic resin powder. The titanium content of the titanium nitride is not less than 75%, the nitrogen content is not less than 18%, the carbon content is not more than 3%, and the oxygen content is not more than 2%;

[0028] 2) The raw materials in step 1) and anhydrous ethanol are accurately weighed according to the mass ratio of 10:0.1-0.5, and then mixed for 5-30 min;

[0029] 3) The material obtained in step 2) is used to obtain a titanium nitride disc sample by a powder tabletting method, and the forming pressure is 10-100 MPa;

[0030] 4) The titanium nitride disc sample obtained in step 3) is dried in a drying oven at 10-300 DEG C with blast drying to obtain a stable granulation material;

[0031] 5) The granulation material obtained in step 4) is sintered in a high-temperature atmosphere sintering furnace under a nitrogen atmosphere at a heating rate of 2-30 DEG C / min to 800-1700 DEG C for 0.5-12h to obtain a sintered granulation material;

[0032] 6) Crush the sintered granules from step 5) and sieve them through a 20-300 mesh screen to obtain titanium nitride particles with a particle size of 0.01-1.5 mm.

[0033] Implementation 1

[0034] (1) Weigh out 30 parts of titanium nitride particles of 0-1 mm, 30 parts of particles of 1-2 mm, and 10 parts of fine powder of 5 micrometers. Weigh out 30 parts of fine zirconium oxide powder of 320 mesh. First, put the fine titanium nitride powder of 5 micrometers and the fine zirconium oxide powder of 320 mesh into a ball mill and premix for 30 minutes to obtain a mixed powder. Add the weighed titanium nitride particles and the mixed powder into a mixer and dry mix for 5 minutes. Add 5 parts of thermosetting liquid phenolic resin and mix again for 15 minutes. Discharge the material.

[0035] (2) Weigh the mixed materials, add them into the mold of the molding machine, and press them into shape.

[0036] (3) Place the molded product into a drying kiln and dry it at 200℃ for 24 hours;

[0037] (4) Place the dried product into the furnace, seal it, and introduce nitrogen or argon gas. Under nitrogen or argon atmosphere protection, raise the temperature to 1500℃, heat for 8 hours, and let it cool naturally to below 100℃. Open the kiln door and remove the product from the furnace.

[0038] (5) Testing and packaging.

[0039] Implementation 2

[0040] (1) Weigh out 30 parts of titanium nitride particles of 0-1 mm, 40 parts of particles of 1-2 mm, and 20 parts of fine powder of 5 micrometers. Weigh out 10 parts of fine zirconium oxide powder of 0-1 mm. First, put the 5-micrometer titanium nitride powder and the 320-mesh zirconium oxide powder into a ball mill and premix for 30 minutes to obtain a mixed powder. Add the weighed titanium nitride particles and the mixed powder to a mixer and dry mix for 5 minutes. Then add 5 parts of zirconium sol and mix for a second time for 15 minutes. Discharge the material.

[0041] (2) Weigh the mixed materials, add them into the mold of the molding machine, and press them into shape.

[0042] (3) Place the molded product into a drying kiln and dry it at 110℃ for 24 hours;

[0043] (4) Place the dried product into the furnace, seal it, and introduce nitrogen or argon gas. Under nitrogen or argon atmosphere protection, raise the temperature to 1600℃, heat for 10 hours, and let it cool naturally to below 100℃. Open the kiln door and remove the product from the furnace.

[0044] (5) Testing and packaging.

[0045] Implementation Three

[0046] (1)Titanium nitride: 0-1 mm particles 15 parts, 1-2 mm particles 20 parts, 5 micron fine powder 5 parts, 320 mesh zirconia fine powder 30 parts. First, the 5 micron titanium nitride fine powder, 320 mesh zirconia fine powder is put into the ball mill for pre-mixing for 30 minutes to obtain a mixed powder. The weighed titanium nitride particles and the mixed powder are added to the mixing machine and dry mixed for 5 minutes. 5 parts of thermosetting liquid phenolic resin is added and mixed for 15 minutes. The product is discharged;

[0047] (2) The mixed material is weighed and added to the molding machine mold for pressure molding;

[0048] (3) The molded product is placed in a drying kiln and dried at 200°C for 24 hours;

[0049] (4) The dried product is placed in a furnace body, sealed, and nitrogen or argon is introduced. Under the protection of nitrogen or argon atmosphere, the temperature is raised to 1500°C, heated for 8 hours, and naturally cooled to below 100°C. The kiln door is opened and the product is discharged;

[0050] (5) Detection, packaging.

[0051] Example four

[0052] (1)Titanium nitride: 0-1 mm particles 15 parts, 1-2 mm particles 20 parts, 5 micron fine powder 5 parts, 320 mesh zirconia fine powder 30 parts. First, the 5 micron titanium nitride fine powder, 320 mesh zirconia fine powder is put into the ball mill for pre-mixing for 30 minutes to obtain a mixed powder. The weighed titanium nitride particles and the mixed powder are added to the mixing machine and dry mixed for 5 minutes. 5 parts of thermosetting liquid phenolic resin is added and mixed for 15 minutes. The product is discharged;

[0053] (2) The mixed material is weighed and added to the molding machine mold for pressure molding;

[0054] (3) The molded product is placed in a drying kiln and dried at 200°C for 24 hours;

[0055] (4) The dried product is placed in a furnace body, sealed, and nitrogen or argon is introduced. Under the protection of nitrogen or argon atmosphere, the temperature is raised to 1500°C, heated for 8 hours, and naturally cooled to below 100°C. The kiln door is opened and the product is discharged;

[0056] (5) Detection, packaging.

[0057] Comparative Example One

[0058] The difference between Example One and Comparative Example One is that no titanium nitride is added in Comparative Example One.

[0059] Comparative Example Two

[0060] In Example 1, the titanium nitride particles are 0-1 mm particles.

[0061] Comparative Example 3

[0062] In Comparative Example 3, the titanium nitride particles are 1-2 mm particles.

[0063] Comparative Example 4

[0064] In Comparative Example 4, the titanium nitride particles are 5 micron fine powder.

[0065] Comparative Example 5

[0066] In Comparative Example 5, the titanium nitride includes only 0-1 mm particles 30 parts, and does not include titanium nitride fine powder.

[0067] Comparative Example 6

[0068] In Comparative Example 6, the titanium nitride includes only 0-1 mm particles 100 parts, and does not include titanium nitride fine powder.

[0069] Comparative Example 7

[0070] In Comparative Example 7, the titanium nitride includes only 1-2 mm particles 30 parts, and does not include titanium nitride fine powder.

[0071] Comparative Example 8

[0072] In Comparative Example 8, the titanium nitride includes only 1-2 mm particles 100 parts, and does not include titanium nitride fine powder.

[0073] Comparative Example 9

[0074] In Comparative Example 9, the titanium nitride includes only 5 micron fine powder 30 parts, and does not include titanium nitride particles.

[0075] Comparative Example 10

[0076] In Comparative Example 10, the titanium nitride includes only 5 micron fine powder 100 parts, and does not include titanium nitride particles.

[0077] Product Performance Testing

[0078] The products prepared in the examples and comparative examples were tested for normal temperature pressure resistance and thermal shock resistance, and the test results are as follows:

[0079] Room temperature compressive strength / MPa Thermal shock resistance (1100°C to water) / cycles Example 1 350 38 Example 2 343 34 Example 3 310 28 Example 4 338 32 Comparative Example 1 230 7 Comparative Example 2 296 20 Comparative Example 3 308 22 Comparative Example 4 276 18 Comparative Example 5 266 16 Comparative Example 6 243 14 Comparative Example 7 290 21 Comparative Example 8 281 20 Comparative Example 9 303 26 Comparative Example 10 322 27

Claims

1. A method for producing a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material, characterized in that: Includes the following steps: (1) Granulation of titanium nitride fine powder: titanium nitride fine powder is thoroughly mixed with phenolic resin powder, anhydrous ethanol is added for mixing, pressure molding, drying, nitriding sintering, and then crushed into titanium nitride particles. (2) Premix titanium nitride fine powder and zirconium oxide fine powder in proportion to obtain mixed powder, add titanium nitride particles and mixed powder to a mixer for dry mixing, then add binder for secondary mixing, and discharge the material; (3) Add the material obtained in step (2) into the mold to form and then unmold; (4) Dry the product formed in step (3); (5) Place the dried product from step (4) into the furnace, heat it under an inert atmosphere, and cool it to obtain the desired product; In step (1), the titanium nitride particles include particles with a diameter of no more than 1 mm and particles with a diameter of 1-2 mm.

2. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (1), the titanium nitride fine powder has a titanium content of not less than 75%, a nitrogen content of not less than 18%, a carbon content of not more than 3%, and an oxygen content of not more than 2%.

3. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (2), the mass ratio of titanium nitride, zirconium oxide and binder is (40-90): (10-60): (3-6).

4. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (2), the zirconium oxide purity is not less than 94% and the particle size is less than 320 mesh.

5. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 4, characterized in that: The zirconium oxide is either an amorphous monoclinic zirconium oxide or a stable zirconium oxide.

6. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 5, characterized in that: The stabilized zirconium oxide stabilizer is calcium oxide or yttrium oxide.

7. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (2), the binder is one or both of thermosetting phenolic resin and thermoplastic phenolic resin.

8. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (2), titanium nitride fine powder and zirconium oxide fine powder are premixed in proportion for 30 minutes, titanium nitride particles and mixed powder are dry mixed for 5 minutes, and secondary mixing time is 15 minutes.

9. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (4), the drying temperature is 110-200℃ and the drying time is 24h.

10. The production method of a sizing nozzle for a steelmaking tundish made of zirconium oxide composite material according to claim 1, characterized in that: In step (5), the inert atmosphere is a nitrogen atmosphere or an argon atmosphere, the heating temperature is 1400-1500℃, and the heating time is 3-10h.