JPS609985B2 - Heat resistant sheet for molten metal casting - Google Patents

Description

Detailed Description of the Invention 2 The present invention relates to a heat-resistant sheet for molten metal casting, and more specifically, the present invention relates to a heat-resistant sheet for molten metal casting, and more specifically, it is made of two or more types of inorganic fibers selected from high melting point, medium melting point, and low melting point inorganic fibers having different softening and melting temperatures. The main component is inorganic fibers, and one or two of natural or synthetic fibers and metal fibers.
An adhesive and one or two of metal oxides, silicates, alkali metal salts, alkali metal salts, phosphates, metal powders, and carbon powders as adhesion promoters.
A heat-resistant sheet for molten metal casting,
A heat-resistant sheet for molten metal casting combined with metal wire or wire gauze for the purpose of further imparting strength to the sheet, and carbonaceous or heavy hydrocarbon impregnation in the sheet for the purpose of adjusting the melting rate of the sheet. The present invention relates to a heat-resistant sheet for molten metal casting in which a layer is formed.

BACKGROUND ART Various heat-resistant, non-combustible, or electrically insulating sheets mainly made of glass fibers, rock wool fibers, mineral wool fibers, etc. have been known. However, although these sheets have various levels of melting temperature indicating heat resistance,
Little consideration was given to the composition and physical properties of the molten state. When glass fiber, rock wool fiber, mineral birch fiber, etc. are used for general non-combustible, heat-resistant building materials, electrical insulation materials, etc., these woven fabrics are melted and the Composition is not a problem, but if it is used for casting or ingots of molten metal, the sheet made from these fibers must have a composition that does not contain harmful components as molten flux in molten metal. It is necessary that there be.

For example, the majority of commercially available mineral deposits are anthophyllite, basalt, and tributary rocks, all of which are magnesium silicate and contain 10 to 20% magnesium oxide. It is common knowledge in steel smelting that magnesium oxide is a harmful component in the form of molten flux, and inorganic fibers containing large amounts of magnesium oxide, not only ``key chain fibers'', are ``unsuitable for use in molten metal casting. Among commercially available inorganic fibers, it is necessary to select one with a low content of magnesium oxide.As mentioned above, many mineral fibers have a high content of magnesium oxide, but if you use wollastonite-based potted cotton, The magnesium oxide content is low. Iron oxide also promotes oxidation of the molten metal, so it must be low. The present invention has a composition in which the components after melting can act as a flux for the molten metal (hereinafter referred to as molten flux composition). The present invention relates to a heat-resistant sheet with properties taken into consideration.An object of the present invention is to provide a heat-resistant sheet for molten metal casting, which has high heat resistance with a melting temperature of 80,000 or higher and has a molten flux composition.

The heat-resistant sheet for molten metal casting of the present invention can be rolled into a cylindrical body and used as a splash prevention pipe in metal overcasting, and can be placed at the bottom of the ingot casting to prevent splashing during the initial stage of the overcasting process. or suppressing the initial jet flow of the lower sea method, adding it to the surface of molten metal in a container to dissolve floating impurities, and suppressing metal splash and Korean heat during casting and welding operations. It can be widely used as a lining material for areas that require fire resistance and heat resistance.

In these applications, the use conditions include the heat-resistant sheet's mechanical strength from room temperature to high temperature, melting temperature, melting speed, degree of "wetness" to molten slag and metal, and composition and physical properties of the flux after melting. Adjust accordingly.
The composition of the heat-resistant sheet for molten metal casting in the present invention and its manufacturing method will be specifically described.

One or more types of inorganic fibers with different softening and melting temperatures.
In more detail, silica/alumina ceramic fibers such as kaolin fibers with high melting points (over 1300°C), fused silica fibers such as quartz fibers, carbon fibers, etc.
0%, rock wool fiber with medium melting point (1100-130000),
Magnesium oxide (M
g○) Blend in an appropriate amount so that the content is 3% by weight or less. In this case, in addition to magnesium oxide, iron oxide also promotes the oxidation of the metal, so it is not preferable as a melt flux composition of the molten metal, so the iron oxide is adjusted to 1% or less. This substantially determines the melting temperature and composition of the fibrous skeleton of the heat-resistant sheet.

In order to improve the strength of the fibrous skeleton, metal fibers made of materials such as iron, aluminum, and stainless steel may be mixed. However, a mixture of only these inorganic fibers,
There is no adhesion of fibers and there is little entanglement. Therefore, 0 to 30% of one or more natural or organic synthetic fibers is added to the inorganic fiber mixture to promote the entanglement effect and provide adhesive properties at the same time. Examples of husbandry fibers include wood pulp, cotton pulp, and L-cotton yarn; examples of organic synthetic fibers include polyethylene, polypropylene, vinylon,
Examples include various fibers such as nylon, acrylic, polyester, and rayon. Furthermore, a small amount of adhesive is added to increase the strength of the sheet.

Adhesives include starch, PVA, acrylic,
Epoxy, urea, phenol, vinyl acetate, and other synthetic resin materials are used.Adhesives can be added in the form of latex, emulsion, aqueous solution, powder, fiber, etc. There are two methods: adding it before forming the paper web of the sheet, and adding it after forming the paper web of the sheet by spraying, impregnation, coating, or a combination thereof, and either of these methods is collected. According to research conducted by the present inventors, the method of adding ``emuljoso'' or fibrous material before forming the paper web of the sheet showed good results. To form the above-mentioned fibers and adhesive, the mixture is uniformly dispersed in water or air.

Furthermore, in the heat-resistant sheet for molten metal casting of the present invention, the inorganic fibers are provided with fusion properties at high temperatures, the sheet is prevented from collapsing due to thermal decomposition of the organic fibers, and at the same time, the molten flux composition is suitable for the application. First, the voids in the fibrous skeleton are filled with an inorganic substance.

Examples of fusion promoters include metal oxides such as titanium oxide, salts of alkali metals and alkali metals such as sodium, potassium, calcium, and barium, fine powders of silicates,
One or more types of phosphates are used. Metal powders such as aluminum, ferrosilicon, calcium silicon, and ferromanganese are sometimes used as part of the fusion promoter for the purpose of deoxidizing molten metal. These adhesion promoters are added in an amount of 20 to 8% by weight based on the aforementioned fiber mixture. Addition of the adhesion promoter can be carried out by dispersing it in the aforementioned fiber mixture before forming the paper web of the sheet;
There is a method in which a suspension containing a fusion promoter is added to the formed sheet by any one or a combination of spraying, impregnation, coating, and the like. According to the research of the present inventors,
The latter method gives good results. Furthermore, for the purpose of improving the mechanical strength of the sheet, there are methods in which metal wires or silk are incorporated or bonded at the same time as the sheet is formed, and methods in which metal wire or silk is bonded or sandwiched after the sheet is formed. There is.

Both methods show good results. By the above manufacturing method, a heat-resistant sheet having a thickness of 0.2 to 5 mm can be obtained, which maintains a molten flux composition suitable for the purpose of use and appropriate mechanical strength at room temperature and high temperature.

Further, when it is necessary to impart "difficult wettability" properties to the molten slag or molten metal and to slow down the apparent melting rate while maintaining the L or low melting point composition, the heat-resistant sheet is subjected to the following treatment.

In other words, carbonaceous fine particles such as carbon black are dispersed in a liquid containing an adhesive, or a heat-resistant sheet is soaked in heated and liquefied tar or asphalt to impregnate carbonaceous fine particles or heavy hydrocarbons. Form a layer.

In this way, if a heat-resistant sheet with ionic bonding properties is impregnated with a substance that has a chemical bond different from that of molten slag or molten metal with metallic bonding properties, the "wetting" that forms the molten slag and metal will be significantly reduced. Moreover, aggregation due to melting of the heat-resistant sheet is prevented, and the melting speed of the sheet is slowed down. The melting temperature of the heat-resistant sheet according to the present invention is significantly higher than that of known heat-resistant sheets, nonflammable sheets, or electrically insulating sheets, and is in the range of 800 oo to 1450 oo. It can be easily adjusted depending on the type and amount added.

The heat-resistant sheet of the present invention has a heat resistance of 800 qo or more, melts and is consumed when the temperature exceeds a certain temperature, and is designed to have a composition suitable for molten metal flux, so it can be cast as a cylindrical body. In addition to being used for lumps, it can be used for various other purposes.

For example, if a board is formed by laminating several sheets with a thickness of ~1.0 to 1.2, this can be used as a lining material for a tundish. A sheet can be placed at the bottom of the mold to suppress the initial jet flow of the pouring process. By adjusting the melting temperature to a low level and cutting a heat-resistant sheet with reduced stiffness into ribbons and placing them between the mold and the surface plate, it is possible to prevent so-called "molten metal leakage."

In addition, if a sheet with a thickness of 0.5 or less is used as a bag for storing powder for agglomeration, a heat-generating heat insulator, etc., the timing of the bag breaking due to heat can be adjusted. In addition, the heat-resistant sheet of the present invention can be processed in combination with corrugated processing, metal wire, metal foil, thin metal plate or wire mesh, and coated with other materials. Various shapes depending on the purpose such as impregnation processing, etc.
You can also configure it. Next, examples of the present invention will be shown.

Add 5% vinylon fiber as an organic synthetic fiber and 4% by weight (solid content) of an aqueous polyvinyl alcohol solution as an adhesive to a mixture of inorganic fibers A, B, and C (fiber composition will be described later), and mix them uniformly in water using a pulper. to create a sheet using a cylinder paper machine.

Of these sheets, A and B were impregnated in a suspension containing silica flour as a silicate powder and sodium silicate as an alkali IJ metal salt, and 3% by weight of silica flower and 5% by weight based on the sheet weight. of sodium silicate. A heat-resistant sheet having a thickness of about 1 yam was produced.

The numerical values of three types of heat-resistant sheets A, B, and C, which have different characteristics, are shown in the following table. A is ceramic fiber (Mg
0 component trace) 75% "Rock wool fiber (Mg○ component 4.9%)
The inorganic fiber blending ratio of 20% and 5% glass fiber has the highest melting temperature and the highest strength at high temperatures.

B has a blending ratio of inorganic fibers of 55% ceramic fiber (M and traces of components), 40% rock wool fiber (4.9% Mg○ component), and 5% glass fiber, and the melting temperature is about 200q higher than that of A.
o Low.

C is an inorganic fiber blending ratio of 50% rock wool fiber (4.9% Mza0 component) and 50% glass fiber, excluding ceramic fiber (trace of Mg○ component), and is impregnated with silicic acid fine particles. It has the lowest melting temperature.

As fiber composition D, instead of 50% of the rock wool fiber of C, 50% of continuous cotton fiber (wollastonite slag wool Mg○ component 6.1%) was used.
A heat-resistant sheet was produced in the same manner except that % was used.

Its characteristics are shown in the table. Next, for comparison, as fiber blend E, mineral wool fiber (orthophylle-based slag wool Mg0 component 15%,
A heat-resistant sheet was prepared in the same manner using 50% Fe203 (7%) and 50% glass fiber.

Its characteristics are shown in the table. The Mg○ component of the sheet is 5.0%F
E203 is 3.5%, which is unsuitable for the composition of molten flux for steel, etc., Mg0 is 3% by weight or less, Fe
203 needs to be 1% by weight or less. As described above, the heat-resistant sheet of the present invention can have heat resistance and melt flux composition depending on the purpose of use.

Among the embodiments of the present invention, C has the lowest melting point and should be used in applications where it is necessary to form a molten flux fairly quickly. By impregnating and fixing 2.5% carbon black into this C sheet, the melting rate can be significantly slowed down. From any location on the sheet, base 1
A right-angled triangle with a height of 5 meters was cut out, fixed upright on a refractory with an inclination of approximately 80o, and placed in an electric muffle furnace heated to a constant temperature for softening and melting time. By measuring , it is possible to compare melting rates. A temperature higher than the melting point of C sheet, 1020 oo, was selected, and the softening and melting times of C sheet and a sheet impregnated with 25% carbon black were compared, and the results are as follows. That is, even if the melting points of the heat-resistant sheets are the same, this impregnation treatment can significantly slow down the melting rate.

Claims (1)

[Claims] 1 Selected from ceramic fibers with high melting points, fused silica fibers, carbon fibers, rock wool fibers with medium melting points, mineral wool fibers with low melting points, asbestos fibers with low melting points, and glass fibers, with a magnesium oxide (MgO) content of 3% by weight in the composition. % or less, iron oxide (Fe_2
O_3) The main component is two or more types of inorganic fibers with different softening and melting temperatures, with a content of 1% by weight or less, and one or more types of natural or synthetic fibers, or iron, aluminum, and stainless steel as necessary. A fiber mixture containing one or more selected metal fibers, an adhesive, and a fusion promoter selected from metal oxides, silicates, alkali metal salts, alkaline earth metal salts, and phosphates. Thickness 0.2 to 5, containing one or more types and, if necessary, a carbonaceous or heavy hydrocarbon substance as a melting rate reducing agent.
1. A heat-resistant sheet for molten metal casting, characterized in that it is a sheet of 1.0 mm in diameter and has a metal wire or wire mesh on the surface or inside of the sheet as necessary.