JPH07308756A - Sliding nozzle plate - Google Patents

Abstract

PURPOSE:To apply a sliding nozzle plate to steels not durable in the conventional plate consisting of one material, to improve the durability, and to suppress the manufacturing cost of the plate. CONSTITUTION:Two or more kinds of different materials are arranged in the solid body of an SN plate without intentionally mixing them, formed and fired, thereafter the different materials are joined without the mortar, castable or the like. The SN plate can be made high in durability and low in cost by combining the material so that the highly corrosion resistant material is used at the important part (a) and the inexpensive material is used at the unimportant part (b). Thus, the unit requirement of the steel-making process can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding nozzle plate for controlling the flow rate of molten steel.

[0002]

2. Description of the Related Art When flowing molten steel from a ladle to a tundish or from a tundish to a mold, a sliding nozzle plate (hereinafter referred to as SN plate) installed at the bottom of the ladle or tundish is used. The flow rate is controlled. Conventionally, the SN plate is mainly made of a material such as high alumina or alumina carbon. However, the following problems occur when such a single material is used. That is, a rapid thermal shock caused by the molten steel flow causes radial cracks around the nozzle hole, and the cracks cause a risk of leakage of molten steel. Further, so-called throttle injection is generally performed for controlling the flow rate of molten steel. At this time, damage (melting loss) of the edge portion of the nozzle hole and the portion hit by the molten steel flow progresses, and there is a risk of molten steel leakage due to the enlargement of the hole diameter and insertion of a metal into the edge portion. From the above viewpoints, the SN plate has thermal shock resistance and excellent erosion resistance,
Is required. However, it is difficult to satisfy the above with a single material as described above.

[0003]

As a means for solving the above problems, a method (a so-called ring method) in which a highly durable material such as zirconia formed in a ring shape only around the nozzle hole is arranged is known. It is known. In the case of this ring system, the ring and the material of the outer edge thereof are joined via mortar or castable. However, this joint portion is often damaged preferentially due to the sliding of the plate, and there is a risk of leakage of molten steel from this portion, which may cause ingots and the like.
Further, the work of joining the rings and the work of casting by casting are troublesome and cause a cost increase.

[0004]

SUMMARY OF THE INVENTION The present invention aims to solve the above problems. The details are given below. The present invention does not intentionally mix two or more different materials, arranges and molds in one SN plate solid, and after firing, joins the different materials with mortar or castable material. Characterized by not being.

[0005]

Alumina carbonaceous material, high alumina material, magnesia material, zirconia material, etc. are selected as the refractory material constituting the plate brick, and a combination of homogeneous materials (for example, a combination of alumina carbon material and alumina carbon material, etc. ) And a combination of different materials (for example, a combination of alumina carbonaceous material and zirconia material). However, in general, for the important parts that are the nozzle hole peripheral part and the sliding part, a material with more excellent corrosion resistance is selected, and for the non-important part that is the outer edge part, a relatively inexpensive material is used. Applied. The plate in which these materials are combined is formed at the same time by a high pressure press at the time of molding, and then subjected to a process such as firing and further subjected to pitch impregnation treatment, caulking treatment and the like for use.

In the product of the present invention, a material having excellent melting resistance is selected around the nozzle hole and in important parts such as sliding parts. It is applicable and can improve durability. Further, a relatively inexpensive material can be applied to the non-important portion of the outer edge portion, and since the work of casting such as mortar set and castable is eliminated, the manufacturing cost of the plate can be kept low. Examples will be described below with reference to the drawings.

[0007]

EXAMPLE As shown in Table 1, two material combinations of different alumina-carbon materials, which are the same material system, were used in the peripheral part of the nozzle hole C and the sliding surface part (important part a) and its outer edge part (non-important part b). The SN plate which was applied to, and formed at the same time as molding, and then subjected to firing, pitch impregnation treatment, caulking treatment, etc. As a result, the durability improvement as shown in Table 2 was obtained.

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

As described above, in the SN plate according to the present invention, by combining a material having high corrosion resistance in the important part and a cheap material in the non-important part, it is possible to reduce the service life and the cost. As a result, it is possible to contribute to the reduction of the original unit price in the steel process.

[Brief description of drawings]

FIG. 1 is a plan view of an SN plate of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

[Explanation of symbols]

 (A) Important part (b) Non-important part (c) Nozzle hole (d) Iron skin

Claims (3)

[Claims] 1. A sliding nozzle plate in which the material around the nozzle hole C through which molten steel passes and the sliding surface portion (important portion a) and its outer edge portion (insignificant portion b) are made of different materials. 2. The sliding nozzle plate according to claim 1, which is formed by firing. 3. A sliding nozzle plate which is formed simultaneously at the time of molding without using mortar, castable or the like at the joint of (important part a) and (important part b) of different quality materials.