Method for preparing zirconia sizing nozzle by adding magnesium-rich spinel micropowder

A magnesia-rich spinel and sizing nozzle technology is applied in the field of adding magnesia-rich spinel fine powder to prepare zirconia sizing nozzles, which can solve problems such as agglomeration and bonding, and achieve reduced porosity, reduced thermal expansion coefficient and Modulus of elasticity, effect of improving thermal shock stability

Inactive Publication Date: 2017-01-04
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Aiming at the defects and deficiencies in the prior art, according to the research results of the National Natural Science Foundation of China project undertaken by the research group "Research on the Fracture Mechanism and Service Life Improvement of Zirconia Calibration Nozzle Stabilizer Desolvation Particles" (Project No. 51372193), the present invention It solves the problem of agglomeration and bonding in the existing zirconia sizing nozzle co-grinding and granulation process, humidification granulation and billet aging process, and can solve the problem of composition adjustment, introduction of spinel phase and prevention of Problems such as stabilizer desolvation further improve the service life of zirconia sizing nozzles

Method used

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Examples

Experimental program
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Effect test

preparation example Construction

[0019] In the present invention, magnesium-rich spinel micropowder is added in the preparation process of zirconia sizing nozzle. First, the excellent performance of spinel is used to prevent elements in molten steel from diffusing to zirconia particles. The second is to prevent the reaction of the stabilizer magnesia and alumina to form spinel, which prevents the further desolvation of the stabilizer in the particles; the third is that the surplus magnesia stabilizer is finely dispersed in the spinel, which can significantly Particle sticking problem preventing magnesium oxide hydration and humidified granulation process. Experimental data show that the volume density of zirconia sizing nozzle prepared by adding magnesium-rich spinel powder is about 3-5% higher than that of the ordinary preparation process of adding magnesium oxide powder, and the porosity of the finished product is reduced by 5.0-6.5%. There is no hydration bonding phenomenon of magnesium oxide, and the serv...

Embodiment 1

[0022] Step 1, preparation of co-milling powder:

[0023] 1) The raw materials include partially stabilized zirconia powder, monoclinic zirconia powder and magnesium-rich spinel powder, and the chemical composition of the partially stabilized zirconia powder is (wt%): ZrO 2 =95.02, HfO 2 =2.04, MgO=2.61, CaO=0.03, Al 2 o 3 =0.03, loss on ignition is 0.27, particle size is D 95 =49.82μm; the chemical composition of monoclinic zirconia powder is (wt%): ZrO 2 +HfO 2 = 98.72 and SiO 2 =0.27, the particle size of monoclinic zirconia is D 50 = 1.87 μm, D 95 2 %=0.67, Al 2 o 3 %=37.22, the particle size composition is D 50 = 0.48 μm, D 90 = 0.97 μm.

[0024] According to the proportion of partially stabilized zirconia micropowder, monoclinic zirconia micropowder and magnesium-rich spinel micropowder in the ratio of 48:47:5, the above materials are put into a polyurethane ball mill tank, and zirconia ceramic balls are used. Co-grind for 24 hours to ensure that the raw mat...

Embodiment 2

[0032] The difference between this example and Example 1 is that the dosage ratio of partially stabilized zirconia micropowder, monoclinic zirconia micropowder and magnesium-rich spinel micropowder in step 1 is adjusted to 47:47:6, and the magnesia stabilizer is added and presynthetic spinel content. According to the accurate proportion of partially stabilized zirconia, monoclinic zirconia and magnesium-rich spinel powder, put the above materials into a polyurethane ball mill tank, use zirconia ceramic balls, and grind for 24 hours to ensure that the raw materials are fully mixed. ; Due to the increase in the content of the magnesium oxide stabilizer, the firing temperature in step 4 is adjusted to 1710°C. The average service life of the prepared fine particle type zirconia sizing nozzle reaches 41.6 hours, the highest is 42 hours, and the lowest is 40 hours, which is slightly lower than that of Example 1, and the service performance is stable.

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Abstract

The invention discloses a method for preparing a zirconia sizing nozzle by adding magnesium-rich spinel micropowder. The method includes the steps that magnesium-rich spinel micropowder, a binding agent and powder are subjected to wetting granulation to obtain granules, and the granules are fired at 1710-1720 DEG C to obtain the zirconia sizing nozzle, wherein the powder includes partially-stabilized zirconia micropowder, monoclinic zirconia micropowder and magnesium-rich spinel micropowder, and the use level ratio of partially-stabilized zirconia micropowder to monoclinic zirconia micropowder to magnesium-rich spinel micropowder is (45-50):(45-50):(4-6). Compared with a common sizing nozzle obtained through a preparation process of adding magnesia micropowder, the volume density of the zirconia sizing nozzle obtained through the method is increased by 3-5% or so, and the porosity of the finished product is reduced by 5.0-6.5%; besides, the phenomenon of magnesia hydration caking does not occur in the granulation process, and the service life of the zirconia sizing nozzle can reach 40 h or longer. The method solves the problem that in the process of adding a magnesia micropowder stabilizer into monoclinic zirconia for wetting granulation, magnesia hydrated particles are caked.

Description

technical field [0001] The invention relates to a preparation process for a functional refractory material used in a continuous casting tundish for controlling molten steel flow in the iron and steel metallurgy industry, in particular to a method for preparing a zirconia sizing nozzle by adding magnesium-rich spinel micropowder. Background technique [0002] The sizing nozzle refers to a functional device made of high-temperature structural ceramics installed at the bottom of the continuous casting tundish. Its main function is that the static pressure of the molten steel in the tundish remains basically unchanged, the molten steel flows into the crystallizer through the sizing nozzle, and the crystallizer is cooled by a large flow of water to take away the heat released when the molten steel solidifies, so that the molten steel solidifies into a billet. Since the heat taken away by the water cooling of the mold is limited, the amount of molten steel flowing into the mold pe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/66C04B35/482C04B35/622
CPCC04B35/482C04B35/622C04B2235/5445C04B2235/5436C04B2235/3222
Inventor 薛群虎杨光赵亮
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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