JPS6049157B2 - High durability sliding nozzle plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refractory plate for controlling the flow rate of molten metal that is highly stable and prevents crack initiation and expansion.

As a flow rate control device for molten metal, a sliding gate nozzle (hereinafter referred to as SN type) is attached to the bottom of a molten metal (hereinafter referred to as molten steel) container and is used.

These devices have two nozzle holes in different locations.
There are two (sometimes three) heat-resistant plates, and by sliding one plate, the nozzle hole is opened and closed.
The flow rate of molten steel is controlled. These plates are subject to rapid heating, wear and erosion by the molten steel. For this reason, the SN type plate must have excellent spall resistance and corrosion resistance, as well as high mechanical strength. Therefore, research on SN plates covers a wide range of topics including materials and manufacturing methods. The material is A1. O,
Quality N. O. -SiO2, magnesia, zirconia, zircon, etc., carbon, SiC)B
, C) Si. N. , BN, etc., such as A1
2Oa-SiO2-C-SiC based carbon bond SN
plates etc. are actually widely used. In many cases, cracks occur in the SN plate radially around the nozzle hole due to the rapid heating caused by the molten steel.

To prevent these cracks from expanding and molten steel leaking out, SN plates have been devised in various ways, such as tightening them with steel hoops, fitting them into iron cases, or tightening the SN plates from the metal frame in which they are incorporated. , has been effective. However, if a crack occurs in a portion that comes into contact with molten steel and coincides with the sliding direction, the cracked portion will rapidly become damaged in the form of a groove, resulting in a reduction in life. Furthermore, if a crack that is perpendicular to the sliding direction expands, a steel leakage accident will occur. The present invention prevents the occurrence and expansion of such cracks in the SN plate and provides an SN plate with excellent stability.

Recently, various structural materials using high-strength inorganic or metallic fibers as strength reinforcing agents have been developed and are widely used. However, most of these materials are used at room temperature, and few of them are suitable as structural materials at high temperatures of 1000° C. or higher. Examples of high-temperature applications include adding several percent of stainless steel (or steel) fiber to monolithic refractories such as fire-resistant castables to strengthen the construction structure and improve spall resistance. Regarding inorganic fibers, attempts have been made to strengthen the strength by dispersing carbon fibers and Al2O3-SiO2 fibers with a length of 50 mm or less in the blend, but it is difficult to disperse the fibers. Furthermore, the fibers are difficult to be fixed during blending in a stretched state, and the effect of adding high-strength fibers cannot currently be obtained. The present invention utilizes ceramic long fibers, which have heretofore been hardly used in refractories, for SN plates.
As mentioned above, the SN plate cannot be broken during use. For this reason, to prevent crack propagation and to facilitate handling of the plate after use, it is wrapped with a steel hoop or secured around its circumference by a steel frame. At room temperature, the SN plate is tightened more tightly than its surroundings, but as the temperature increases during use, the strength of the stay decreases and the tightening effect is almost completely lost. In the present invention, a bundle of high-strength ceramic long fibers is arranged almost S Therefore, the above-mentioned drawbacks have been improved.

As the ceramic fiber, carbon fiber is preferable from the viewpoint of material, strength, etc., and a net (reticular) type is used.

To explain the drawings, Fig. 1 shows an example of a conventional SN plate, and Figs. 2 to 6 show examples of the SN plate of the present invention, where 1 is an SN plate made of carbon bond material, and 2 is a nozzle through which molten steel passes. Hole 3 is a bundle of carbon fibers.

Figures 1 to 3 Figures 3 are cross sections cut in the width direction of the SN plate centering on the nozzle hole, Figures 4 to 6 are plane views of the sliding surface of the SN plate, and dotted lines indicate carbon fibers in the structure of the plate. It is shown that. Many other carbon fiber arrangements are possible. 4 Furthermore, the present invention is not limited to the regipro type SN system,
Also useful for rotary types and others.

Next, examples of the present invention will be described.

Example 1 Sintered alumina 7% by weight, zirconia mullite 20% by weight
, 4% liquid phenol resin with 5% carbon by weight.
% by weight was added and kneaded to prepare an alumina-carbon SN plate formulation.

Next, put half of the prescribed amount of the above mixture into a 750T-FOP (7) SN plate molding frame, and use a tow of Toray carbon fiber) T-200 to make 20Tr1! Spread the n-th mesh, add the rest of the mixture on top, and apply gentle pressure 5 times.
Molding was performed under high pressure P times. After reducing and firing this, it was impregnated with pitch and caulked at 1000°C. Polish the sliding surface and place it in place with 60T! The nozzle hole of Rln was polled. 16 inside the nozzle hole of this SN plate.
A rapid heating spalling test was conducted in a flame controlled at 00°C.

In the SN plate of the present invention, radial cracks centered around the nozzle holes occurred, but the crack surface did not open at all, and the shape before the test was maintained. On the other hand, with conventional products, cracks are S
The N plate was completely traversed or longitudinally divided into four parts around the nozzle hole. As a result of trial use of 20 sets of the plates in a 160t converter ladle, a performance of 6.5 Ch/Set was obtained. Proper same material plate is 5.7Ch/
It was set. The difference between the two lies in the degree of crack expansion.
In the former case, crack expansion was small. Example 2 The composition and carbon fiber were the same as in Example 1, but three carbon fiber tow nets were used so as to equally divide the thickness of the plate into four.

The molding and firing process was also the same as in Example 1. The spalling test results were even better than in Example 1. However, in practical tests, an improvement in life was seen at 6.8ch/Set.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view of a conventional plate, FIG. 2 is a vertical side view of the SN plate of the present invention, FIG. 3 is a vertical side view of another example of the SN plate of the present invention, and FIGS. 4 to 6 are S of the present invention
FIG. 6 is a plan view of different examples of N plates.

Claims (1)

[Claims] 1. In a carbon bond fire-resistant plate containing 5% by weight or more of carbon dioxide, which is used in a flow control device for molten metal and has flow holes for controlling the molten metal, a diameter 300μ or less, length 30mm or more, strength 10
A highly durable sliding nozzle plate characterized by having one or more layers of net made of carbon fiber having a property of 0 kg/mm^2 or more arranged approximately parallel to the sliding surface of the plate.