JP3124374B2 - Refractory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a kiln, ladle, tundish, vacuum degassing apparatus for accommodating and processing molten metal, for example, molten steel, molten steel distribution pipes such as nozzles, immersion pipes, etc. It relates to the refractory used.

[0002]

2. Description of the Related Art In continuous casting of steel, immersion nozzles are used under extremely severe conditions such as contact with mold powder at a high temperature. Therefore, nozzle materials having excellent corrosion resistance and excellent mechanical strength are required. . Conventional Al ₂ O ₃ -C electrolyte immersion nozzle as a nozzle material equipped these conditions have been widely applied. However, as the amount of molten steel passing through the nozzle increases, alumina adheres to and grows on the inner surface of the nozzle, leading to nozzle clogging. In some cases, the alumina adhering to the surface may fall off and cause product defects.

[0003] On the other hand, as the quality of steel materials becomes stricter, it is indispensable to ensure the cleanliness of molten steel, and in order to realize these, it is necessary to minimize the contamination of molten steel from refractories. The contamination from the refractory may be due to the supply of oxygen from the refractory, or the alumina adhered or deposited on the refractory may fall into the molten steel.Therefore, it is necessary to prevent the adhesion and deposition of alumina to the refractory. is there. As described above, establishing measures to prevent alumina from adhering to the inner surface of a refractory is an important issue, and much effort has been made in the past. However, it is hard to say that the nozzle blockage due to the alumina attached and deposited on the inner surface of the immersion nozzle, which is a particularly serious problem, has been solved. To solve this problem, have been developed recently CaZrO ₃ refractory material for a submerged nozzle which contains (JP 64-40154 JP), it has come to be applied.

[0004]

However, CaZ
Even if a nozzle containing rO ₃ is used, the effect of preventing clogging may not be sufficiently exhibited, or the nozzle may be severely melted and casting must be interrupted on the way. To be effectively expressed, Ca
This is a major technical problem for using a ZrO ₃ -containing nozzle. In addition, the CaZrO ₃ -containing nozzle is not an inexpensive material, and the development of an inexpensive non-adhesive material is an important issue.
The present inventors have proposed CaZrO ₃ to solve such a problem.
The present invention has been provided as a result of studying the mechanism for preventing adhesion of the containing nozzle.

[0005]

The gist of the present invention is as follows. (1) The ratio by weight of CaO to SiO ₂ is 1.2 to 2.0.
(= CaO / SiO ₂ )
Containing O _2, CaF of CaO-SiO ₂ -CaF _{2
2 in an amount} of 1 to 15% by weight, and ZrO
_2. A refractory characterized in that 2 contains 60% by weight or less and a carbon material 30% by weight or less . (2) The ratio by weight of CaO to SiO ₂ is 1.2 to 2.0.
CaO and SiO _{2 so} that
_{2 - Al 2 O 3 Al 2} O 3 in -CaF ₂ is 40 wt%
Contains the following, CaF ₂ is contained 1-15 wt%, ZrO ₂ of refractory total weight 60% by weight or less, a carbon material 30
A refractory characterized in that it contains not more than 10% by weight .

Hereinafter, the present invention will be described in more detail. In order to solve the above-mentioned problems, the present inventors have studied and studied the actual state of adhesion of the nozzle which seems to have a sufficient blocking prevention effect in the immersion nozzle containing CaZrO _3, and as a result, the CaZrO _{3 3} (including 30% CaO)
Decomposed to form Zr containing about 10% CaO
O ₂ solid solution and these intergranular matrices contain CaZr
CaO released by decomposition of O ₃ (containing 30% CaO)
And Al ₂ O _{3 from} molten steel and SiO from antioxidants
It revealed that constitutes the oxide phase of CaO-SiO ₂ -Al ₂ O ₃ system by _2.

As a result of further research, CaO-SiO
_2- Al ₂ O ₃ -based oxide is dicalcium silicate (2CaO · SiO ₂ , hereinafter abbreviated as C ₂ S) as shown in FIG.
And gehlenite _{(2CaO · Al 2 O 3 ·} SiO 2, less C ₂ AS abbreviated) and elucidated that these are compositions located on a line connecting a straight line, Al ₂ O ₃ of C ₂ S is to the nozzle inner surface It has been found that it is a key substance for preventing the adhesion and deposition of water and maintaining the nozzle shape.

[0008] If the Al ₂ O ₃ was adhered to when Hosojutsu based on pseudo binary phase diagram of Figure 3 The principle C ₂ S, as shown in FIG. 4, the interface of the C ₂ S and Al ₂ O ₃ Is the liquid phase and C ₂
As a result, AS is generated, and it is considered that this low melting point phase prevents Al ₂ O ₃ from adhering to the inner surface of the nozzle and sintering. The C ₂ AS phase has a function of accommodating the adhering Al ₂ O ₃ in the nozzle, and as shown in FIG.
_{The 2} O ₃ moves into the nozzle. As a result of further study of these reactions, as shown in FIG. 6, the present inventors found that the penetration depth and amount of Al ₂ O _{3 into} the nozzle were increased by including CaF ₂ in C ₂ S, and the present invention was carried out. Achieved.

FIG. 1 shows the effect of improving the adhesion of alumina according to the present invention. It can be seen that the amount of molten steel passing through the nozzle without adhesion has increased significantly. Note alumina adhering to the immersion nozzle inner surface, the function of preventing the sintering wt% ratio of CaO and SiO ₂ is controlled in the range of 1.2 to 2.0, CaF ₂ to C ₂ S phase
Can be achieved by adding
In order to improve the erosion resistance, it is preferable to include a carbon material and ZrO ₂ fine particles. As described above, according to the present invention, there is provided a refractory having a very small amount of adhesion of alumina and hardly being melted.

Next, the present invention will be described with reference to examples.

【Example】

Example 1 As shown in FIG. 7, a test was performed by lining the refractory 2 of the present invention on the inner surface of the alumina graphite shown in 1. The refractory lining of the present invention is a C ₂ S—CaF ₂ —ZrO ₂ —C material, and its component ratio is 45% by weight of ZrO ₂ , 26% by weight of graphite, and dicalcium silicate (C ₂
S) is 26.5% by weight and CaF ₂ is 2.5% by weight. By this immersion nozzle, it is shown in Figure 1 as compared to the C ₂ S-ZrO ₂ -C quality nozzles CaF ₂ no addition the relationship between the deposition thickness and the nozzle passage amount of molten steel discharge hole and casting low carbon steel. It can be seen that the thickness of alumina adhered can be greatly improved by the nozzle material of the present invention. FIG. 7 also shows the position where the thickness of the adhered alumina was measured.

Example 2 The experimental method is the same as in Example 1. The refractory composition lined was CaSiO ₃ , Ca ₃ Si ₂ O ₇ , and Ca ₂ SiO ₄ so that the ratio by weight of CaO and SiO ₂ was 1.7.
(C ₂ S), Ca ₂ SiO ₅ based minerals and SiO ₂ , C
Adjusted by aO, the weight percent of CaF ₂ is 0 to 20%
The effect of CaF _{2 in} C ₂ S on nozzle adhesion was investigated. The refractory material was mixed with 10% by weight of carbon material and 30% by weight of ZrO ₂ ,
The heat treatment is performed at 00 ° C. for 60 minutes. The amount of molten steel that passed through the nozzle was 1200 to 1400 tons, and the effect of ₂ % by weight of CaF on the adhesion thickness is shown in FIG. If CaF ₂ is added too much, the nozzle tends to melt, so CaF 2
It can be seen that there is a limit to the input amount of ₂ .

Example 3 The experimental method is the same as in Example 1. The ratio of the amount of ZrO _{2 to} the amount of carbon was investigated. The amount of molten steel passing through the nozzle is 1200 to 1400 ton. CaO
And the ratio by weight of SiO ₂ is 1.7 (CaO / SiO ₂ )
Was adjusted. FIG. 9 shows the effect of the carbon material mixing ratio on the alumina adhesion thickness, and FIG. 10 shows the effect of the ZrO ₂ compounding ratio. According to the results shown in FIG. 9, when the carbon material is contained in an amount of 30% by weight or more, the effect of dicalcium silicate (C ₂ S) on preventing alumina from adhering is hindered, and the thickness of adhering alumina increases. According to FIG. 10, ZrO ₂ is 60% by weight.
% Or more, the dicalcium silicate (C ₂
The effect of S) on preventing alumina adhesion is hindered, and the thickness of alumina adhesion increases. According to the above results, the carbon material is preferably limited to 30% by weight or less and ZrO ₂ is preferably limited to 60% or less in order to sufficiently function to prevent the alumina adhesion of dicalcium silicate.

[0013]

As described above, CaO and SiO ₂ are blended in a weight ratio of 1.2 to 2.0 (= CaO / SiO ₂ ) so as to generate dicalcium silicate (C ₂ S). C ₂ S-CaF ₂ -ZrO ₂ plus CaF ₂
-C furnaces, ladle, dundish,
Alternatively, by configuring a vacuum degassing device, a flow pipe, and the like, it is possible to prevent Al ₂ O _{3 from} adhering to the surface of the refractory and prevent molten steel contamination. When applied, the nozzle can be effectively prevented from being clogged, thereby improving the productivity of steel and stabilizing the slab quality.

[Brief description of the drawings]

FIG. 1: CaF ₂ is dicalcium silicate (C ₂ S)
Effect of Immersion Nozzle on Alumina Adhesion

FIG. 2 Reaction product in a nozzle when alumina deposition is prevented by a CaZrO ₃ -containing nozzle

FIG. 3 shows Ca ₂ SiO ₄ (C ₂ S) and Ca ₂ Al ₂ SiO
₇ (C ₂ AS) pseudo binary system phase diagram

Fig. 4 Principle of preventing alumina from adhering to a nozzle containing dicalcium silicate (C ₂ S)

FIG. 5 Amount of alumina absorbed in the nozzle

FIG. 6: CaF ₂ is dicalcium silicate (C ₂ S)
Alumina absorption when added to

FIG. 7 shows a nozzle configuration in which an experiment was performed.

FIG. 8: Effect of the amount of CaF ₂ added to dicalcium silicate (C ₂ S) on the thickness of alumina deposited on a immersion nozzle

FIG. 9 shows the effect of the carbon material mixing ratio on the effect of the nozzle material on preventing alumina adhesion.

FIG. 10 shows the effect of the ZrO ₂ mixing ratio on the alumina adhesion preventing effect of the nozzle material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alumina graphite 2 Refractory of the present invention 3 Attached alumina thickness measurement position

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akito Kiyose 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu Works (56) References JP-A-4-37453 (JP, A) JP-A-63-45168 (JP, A) JP-A-2-207951 (JP, A) JP-A-4-94851 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35 / 00 C04B 35/48

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the weight ratio of CaO to SiO ₂ is 1.2.
~ 2.0 (= CaO / SiO ₂ )
Containing O and _{SiO 2, CaO-SiO 2 -CaF} 2 in
CaF ₂ is contained 1-15 wt% of the total weight refractory
Chi ZrO ₂ is 60 wt% or less, refractory, characterized in that the carbon material is <br/> containing 30 wt% or less. 2. The ratio of the weight percentage of CaO and SiO ₂ is 1.2.
Containing CaO and SiO ₂ so as to be to 2.0, CaO
_{-SiO 2 - Al 2 O 3 Al} 2 O 3 in -CaF ₂ 4
0 contained wt% or less, CaF ₂ is contained 1-15 wt%, ZrO ₂ is 60% by weight of refractory total weight or less, refractory, characterized in that it contains carbon material is 30 wt% or less.