JPS58351A - Molten metal surface coating material - 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 The present invention relates to a hot water surface coating material used for the purpose of heat retention and oxidation prevention of #-gold metal.

When casting zinc, aluminum, or alloys of these metals, the ingot is heated in a melting furnace and the resulting molten metal is stored in a storage tank called a bath chamber, hot water storage tank, etc. Usually, the molten metal is pumped out little by little from here or taken out from the tap hole at the bottom of the tank and cast. In this case, it goes without saying that it is necessary to prevent the temperature of the molten metal from decreasing by minimizing the radiation of heat from the molten metal in the storage tank. Especially in the case of the method of pumping the molten metal using Ladle Gin,
Since the upper part of the molten metal storage tank must have an open structure so that it can be pumped out, heat dissipation from the molten metal surface tends to be large, and it is necessary to keep it warm by some means. In the case of aluminum, it not only causes a simple temperature drop, but also reacts with # elements in the air to produce oxides, and reacts with water vapor in the air to produce oxides and water volume. The more oxide particles there are, the more the quality of the cast product inevitably deteriorates, and hydrogen is also absorbed into the bath, causing defects called gas porosity in the cast product.

The flux melting method is well known as a method to solve such problems in temporary storage of molten metal, and the method of waxing the molten metal surface with ceramic fibers (% Kosho 54-2)
No. 0447) has also been proposed. However, in the former case, slacks are hygroscopic, so depending on how they are stored and used, instead of preventing oxidation of the molten metal, they may instead supply moisture and promote oxidation and absorption of hydrogen gas. . In the latter case, although it has a heat-retaining effect, not only is the ceramic fiber drawn up with the molten metal, which is difficult to remove, but also the ceramic fiber is easily mixed into the molten metal, so for example, after the bath water is used up, The drawback was that the ceramic fibers in the storage tank had to be completely removed using a vacuum suction device before injecting new molten metal, which required careful handling.

The present invention has made possible a molten metal heat retention method that does not have the above-mentioned drawbacks! #normal #opencover61E#, that is, the density is 0°7~1
．． 4 g/ai, and the weight loss when heated at 650°C for 3 hours (measured value for the sample after drying at 105°C for 24 hours, hereinafter referred to as ignition loss at 650°C) is 6 weight or less, and The present invention provides a molten metal surface covering material made of a calcium silicate molded body having a block-like shape.

The hot water surface covering material according to the present invention is used in large numbers floating on the hot water surface so that the entire hot water surface is covered. The coating material of the present invention, which is made of a heat-resistant material molded into a lump with a low specific gravity, has good heat insulation properties and hardly allows air to pass through, so if it is suspended densely on the surface of the hot water, Suppress heat dissipation and prevent contact between molten metal and air! Not only does it effectively prevent cooling of the molten metal, oxidation, and generation of watery gas, but there is no risk of it being mixed into the molten metal, unlike ceramic fibers themselves. In other words, even if you replenish the molten metal from above the floating coating material or disturb the scene, the entire coating material will immediately float to the surface of the molten metal, and it is easy to remove it so that it does not enter the ladle.

Therefore, if this coating material is used, the surface of the molten metal can be covered with almost no manual labor, and the molten metal will not be contaminated. Needless to say, in order to make full use of these features, the covering material must be able to withstand harsh usage conditions for a long period of time, but it must also be able to withstand the harsh conditions of use for a long period of time. Moreover, the coating material of the present invention, which is made of a bulky calcium silicate molded body, has excellent heat resistance and thermal shock resistance, and does not easily crack or shrink even when subjected to repeated heating and cooling or uneven heating. ing.

Next, the hot water surface coating material of the present invention will be explained in detail by showing its manufacturing method.

The tk surface area material of the present invention basically follows the well-known method for producing a calcium silicate molded body, and the density of the molded body obtained is 0.7 to 1.4 g7dl, and the ignition loss at 650°C is It can be obtained by employing raw materials and molding conditions such that the weight is 6 weight or less, preferably 5 weight or less.

Setting the density of the molded body within the above range means that when the coating material is placed on the hot water surface, the bottom half sinks in the water and the top half is exposed to the air, which is the most preferable state or a state close to this. This is necessary to improve the thermal insulation properties. In addition, by keeping the 650℃ ignition loss (that is, the amount of water released when heated to 650℃) to 6 seconds or less, shrinkage and cracks will not occur even if subjected to repeated heating or uneven heating with high-temperature bath water. This is necessary not only to provide a high degree of heat resistance, but also to prevent the formation of water vapor in the molten metal due to the release of water vapor during use. It is. This requirement can be achieved by allowing xonotlite to occupy the part of the vector made of calcium silicate, and by not using asbestos, which causes a dehydration reaction at temperatures above 400° C., for reinforcement.

Molding can be done by any method such as casting or press molding.In addition to forming into a block from the beginning, it can also be formed into an arbitrary shape such as a plate, and the resulting molded object is then cut into a block. You may also use a finishing method. As for the shape, a sphere with a diameter of 10=100 am or a polyhedron close to this is preferable. In the case of objects with shapes other than spheres, for example objects with sharp corners or flat surfaces, such as cubes, the corners are likely to wear out, and hot water splashes may land on areas where the flat surface is facing upwards. Because it is easy to stay and oxidize without falling, it is necessary to be careful in selecting the shape.

Next, we will explain the body side of the hot water surface coating material of this @mei, showing its manufacturing method.

[Manufacturing corporation]

This is a method in which a slurry of xonotlite, which has been hydrothermally synthesized in advance, fibrous wollastonite, and water are added to the silicic acid raw material and lime raw material, and mixed uniformly, and after dehydration molding, steam curing and drying are performed.

Keiflt raw materials and lime raw materials include silica gravel, silica stone, 7erosilicon dust, silica, slaked lime, quicklime,
Any material that is normally used as a raw material for producing calcium silicate molded bodies, such as carbide slag, can be used, and the CaO/SiO2 molar ratio is 0°6 to 1.2, preferably 0.7 to 1.0. shall be.

As the zonotrite slurry, one produced by a conventional method can be used, but a mixture of a silicic acid raw material and a lime raw material (Cab/Sin, molar ratio of 0.8 to 1.
Add 10 to 30 times the amount of water to 2.
(vapor pressure of ψ-), and was produced by reacting for 2 to 8 hours with stirring. When an appropriate amount of such zonotrite slurry is blended, the molded product not only has good handling and self-retention properties before curing even without the use of asbestos, but also easily becomes a molded product with low specific gravity, good strength and heat resistance. You can get the product. The preferred blending amount of the zonotrite slurry is: ■Total amount of silicic acid raw material and lime raw material for carving: 10
It is 20 to 170 parts by weight per 0 parts by weight.

As the fibrous wollastonite, a commercially available product such as NYARD-G manufactured by Interpace, Inc. in the United States can be used as it is. When this wollastonite is mixed with 5 to 150 parts of violet per 1100 parts of the silicic acid raw material and lime raw material, the product will have good heat resistance and will not easily crack during manufacturing or use. In addition, the machinability is also improved, so even when it is formed into a thick plate and then cut into a desired shape, the machining is easy and the yield is high.

In addition, a small amount of alkali-resistant glass fiber may be added for the purpose of improving moldability.

After adding appropriate water to the above ## raw materials and making it into a slurry,
As mentioned above, by reducing the degree of dehydration in this process by 4, the density of the product can be adjusted to 0.7 to 1.
4 g/cd, desired L < hao, s ~ r, o g/
It should be about CD. The obtained molded product is transferred to an autoclave and heated to 6 to 20 kli/d, preferably 8
It is steam-cured with ~14ψ- steam and then dried.

It is desirable that the drying be carried out sufficiently at a higher temperature than in the case of producing a normal calcium silicate molded product (for example, for building materials).

[Production method B]

A mixture of slaked lime and silica stone with a CaO/8i0□ molar ratio of about 1 is mixed with about 2 to 6 parts of Portland cement, and a large amount of water is added to form a slurry, which is then added to the mixture in an autoclave while stirring. Heating under pressure produces xonotlite. This is mixed with an appropriate amount of alkali-resistant glass fiber as a reinforcing material, dehydrated and molded, and thoroughly dried with hot air.

[Production method C]

A large amount of water is added to a mixture of quicklime with a Cab/5in2 molar ratio of approximately 1 (but digested with hot water before use) and 7Erosilicon dust to form a slurry, which is then reacted in an autoclave to form a xonotrite slurry. The following steps were followed in the same manner as Manufacturing Method B.

The hot water surface coating material of the present invention, which is a calcium silicate molded body,
Under normal usage conditions, the surface can be used for a long time without getting wet with hot water or wearing out quickly. However, if it is used under conditions where it is repeatedly exposed to particularly strong mechanical shocks, the surface will wear out and cause powder damage. Calcium silicate may float on the surface of the hot water and become easily mixed into the hot water. If it is necessary to avoid this, the surface may be strengthened by a method such as coating with any heat-resistant material within a range that does not impair the excellent percent properties of the #-faced material of the present invention.

As described above, the present invention has succeeded in providing a hot water surface coating material that is extremely effective in retaining heat and preventing deterioration of bath water, and is easy to use.This invention contributes to labor-saving and energy-saving in the casting process, and improves the quality of cast products. It is a great contribution.

The present invention will be explained below with reference to Examples. In addition, in the example “
"part" means the coulometric part.

Example 1 Silica stone powder and lime milk were mixed into CaO/8i0. Mix so that the (molar ratio) is 0°98, add 12 times the amount of water to make 16ψ-
The zonotophyto slurry obtained by reacting with stirring under the water vapor pressure of
YARl)-G) 40 parts) A mixture of 4 parts of alkali-resistant glass fiber and SOO part of water was dehydrated and molded into a thick plate shape, and the resulting molded product was treated with rattan heat for 10 hours under a steam pressure of 9 ky/d. , and dried by placing it in hot air for 4 hours to obtain a plate-shaped molded product mainly consisting of xonotlite. Next, this is cut to produce a large number of spherical bodies (the hot water surface coating material of the present invention) each having a diameter of 50 squares.

Using the above method, five types of hot water surface coating materials were manufactured by gradually varying the drying temperature from 250 DEG C. to 650 DEG C., and their physical properties and heat retention performance were investigated. The heat retention performance test was conducted using a hot water storage tank with an open top structure (inner diameter 501 mm, depth 100 degrees).
The hot water temperature was measured after filling molten aluminum at 00℃ to a depth of 60α, floating the hot water surface covering material on the hot water surface in a close-packed arrangement, and leaving it for 2 hours. This was done by observation.

The manufacturing conditions (drying temperature) and physical properties of each hot water surface covering material and the results of heat retention tests are shown in Summary 1-IN. However, the physical properties are the values measured for the plate-shaped molded product before cutting into a spherical shape.

Claims (1)

[Claims] For use in II melting metal melts, which is made of a calcium silicate molded body having a density of 0.7 to 1.4 tow, a lid loss of 6 weight or less when heated at 650°C for 3 hours, and a block-like shape. Plain board material.