JPS60200866A - Manufacture of high endurance sliding nozzle plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to a sliding gusset (S
N) Regarding a method for manufacturing a plate.

[Technical background]

The SN device is roughly divided into three parts: the upper nozzle, the plate brick consisting of fixed and sliding plates, and the lower nozzle. Among these, the plate brick has the most advanced function that controls the flow of molten metal. This is the required part. Since plate bricks are subjected to the physical and chemical attack of rapid thermal shock and abrasion caused by molten metal flow, the most important properties to have include spalling resistance and erosion resistance.

As described in Japanese Unexamined Patent Publication No. 57-27972, the present applicant has added 1 to 20% by weight of aluminum powder of 100 meshes or less to a refractory raw material and fired it in a nitrogen gas atmosphere. We previously proposed an SN plate with improved mechanical strength and erosion resistance.

However, although both flake and atomized powders are effective in improving mechanical strength and corrosion resistance, their effectiveness in preventing the development of cracks during spalling is too small, and their durability is limited. In order to further improve the properties, it is necessary to improve the spalling resistance.

[Object of the Invention] The present invention provides an SN plate that has high mechanical strength and corrosion resistance, and has significantly improved spalling resistance.

[Structure of the invention]

The object of the present invention is achieved by adding fibers of 8L or A6 alloy under specific conditions to the refractory aggregate.

If the diameter of the fibers is smaller than 10 μm, the fibers will become entangled with each other, resulting in significantly reduced dispersion and poor homogeneity when added to the composition. Furthermore, if jY exceeds 150 μm, the following problems will occur. That is, the SN plate requires abrasive processing using water to ensure the accuracy of the sliding surface, but in this case β.

^ If the β alloy powder exceeds 150 μm, the brick structure will deteriorate significantly when the carbide Aβ generated during firing is digested, and the remaining metal will also be digested, so the particle size should be adjusted to the extent that it is effective in terms of spalling resistance. It turned out that it was impossible to make it coarse.

Furthermore, if the length of the added fiber is shorter than one tuna, the effect of using the fiber instead of the powder will not be achieved. However, if the length is longer than 10 mm, the fibers become entangled with each other, resulting in a problem that the dispersion when added to the composition is significantly reduced.

Therefore use Aj! ,l! The gold alloy fiber has a diameter of 10
~150 μm, the length should be in the range 1 to lQ*m.

In addition, if the amount of i, A4 alloy fiber used is less than 1% by weight, the effect of using the fiber is insufficient;
If the amount is larger than that, the dispersion will be poor and the effect will be reduced.

Carbon is blended to provide durable polling properties and prevent wetness, but unless its blending amount is 1% by weight or more, the effect of improving spalling resistance will be insufficient.

Firing after forming is carried out in a non-oxidizing atmosphere such as in coke powder or gas flow, but the firing temperature is 1000°C.
Digestion resistance cannot be satisfied at lower temperatures. In addition, in order to fully satisfy the digestion resistance, it is necessary to impregnate the pitch after baking and use it as is, or to carry out a caulking process with the aim of smoke-free production to remove the coke from the impregnated pitch coating or from the impregnated pitch. It is necessary to form a film on the surface of the fired product and then perform finishing processing.

The refractory powder used as aggregate may be one or a mixture of two or more powders, including alumina, synthetic mullite, sillimanite andalusite, spinel, magnesia, etc., as long as it satisfies corrosion resistance for SN plates. is available (ihi).

Of course, Si, Aj! , A1 alloy, B4. One type or a mixture of two or more of C and L3N powders can also be used in combination to provide strength and oxidation resistance of ++li strength 44, as long as attention is paid to the durable poling property.

〔Example〕

From the formulations shown in Tables 1 to 3, sizes 650 to 4
50 evenings x 240~200 ■ 50~4011
II+, an SN plate with a nozzle L1 diameter of 85 to 60 m was molded, fired at 1300"C in a coke plea, impregnated with pitch, and caulked at 900°C.The characteristics of this plate are shown in the bottom column of each table. Shown below.

In the manufacturing process of Example 1, digestion occurred when wet polishing was performed before pitch impregnation.

Furthermore, regarding the same Example 1, digestion occurred similarly when wet-polishing the material that was pinch-impregnated and caulked at 900 °C after firing at 900 °C, but no digestion occurred in the product fired at 1000 °C. Ta.

In the case of Table 1, there is no effect on improving spalling resistance unless the length of the fiber used is 1 mm or more, and
If the diameter was not less than 150 μm, digestion occurred and the yield of bricks decreased.

In the case of Table 2, if A1 fiber was used in an amount of 1% by weight or more, there was no effect in terms of spalling resistance, and if it was not used in an amount of 15% by weight or less, quality deterioration occurred.

These samples were subjected to practical tests using high calcium alloy addition steel, high oxygen steel, etc. at an injection temperature of 1610 to 1680°C.

When used in an SN plate for 300T, Comparative Example 1 can withstand only one charge in terms of corrosion resistance, and Comparative Example 2 can withstand only one charge in terms of spalling resistance. Its durability was at its limit. On the other hand, when Examples 1, 2, 6, and 8 were applied, 3 charges were used, but there was still plenty of room at that time.

When used in SN plates for tundishes, Comparative Example 2 could withstand only 3 charges due to deterioration in corrosion resistance, and Comparative Example 1, which was made of lightning conductor steel, could not withstand up to 8 charges. Moreover, in Comparative Example 8, the spalling resistance was poor and the durability was only 3 charges. On the other hand, when Examples 9 and 10 were carried out, 8 charges of 1 river of grapes were obtained.

[Integrated effect]

The present invention successfully improves the spalling resistance of SN plate refractories by using fibers with a specific range of sizes in place of conventional aluminum powder. A durable SN plate can be obtained without making any major changes.

Claims (1)

[Claims] 1. The diameter of the fiber is 10-150μm, the length is 1-1
Kneading a mixture containing 1 to 15% by weight of metallic Aβ fibers or Aβ alloy fibers or a mixture of both within the range of 0.01m and 1% or more of carbon powder by weight;
A method for manufacturing a highly durable sliding nozzle plate, which comprises molding, firing in a non-oxidizing atmosphere at 1000°C or higher, and then performing pitch-containing lJ.