JPS60226438A - Forming refractory composition - 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 provides corrosion resistance and heat insulation for molten metal, such as gutters, crucibles, holding furnaces, and ladles used for transporting and holding molten aluminum and aluminum alloys. The present invention relates to a molding refractory composition for forming containers with high properties.

[Conventional technology]

For the above-mentioned applications, plate-like materials mainly made of calcium silicate and lightweight castable refractory materials are generally used as lining materials that come into direct contact with molten aluminum and aluminum alloys. Among these, calcium silicate-based plate-shaped products are excellent in terms of heat insulation and strength, but because they contain a large amount of crystallization water, they shrink significantly due to dehydration during the manufacturing process of heating and sintering. X 1.5 m
When manufacturing large containers such as 0.5 m bathtubs, it is very difficult to do so without cracking, so the method of assembling formed and sintered plates, assembling them, and joining them with mortar is recommended. It is taken. Therefore, there are problems such as leakage of hot water from the joints and opening of the joints.

On the other hand, lightweight castable refractory materials are suitable for making monolithic structures, but they have low strength and shrink due to dehydration, making it difficult to form and use them as large monolithic containers.
There is a problem with strength.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a refractory composition for molding that solves the above-mentioned problems and allows easy production of large containers for molten aluminum and aluminum alloys that have excellent heat insulation properties, strength, and corrosion resistance.

[Means for solving problems]

Fibrous wollastonite is 35 to 65% by weight of the total with high alumina cement, and the specific surface area by Blaine method is 40%.
00~5ooo11m/g high alumina cement,
Specific surface area by Blaine method is 8000~1.0000Cn
2/g of high alumina cement at a weight ratio of 8 nia to
A total of 35~ with fibrous wollastonite in the ratio of 62 Li
65% by weight, organic binder: ■■0.
1 to 0.5% by weight of a refractory composition for molding, and a molding in which the above formulation further contains organic fibers with a length of 1Q mm or less in an amount of 1 to 0.01% by weight based on the total amount. This invention is based on the person who constituted the service person.

[Effect]

The composition of the present invention is prepared by adding water to the composition, kneading it, and casting it into a mold.
It is used to make fireproof and heat-insulating containers, etc. by hardening and extrusion molding, drying, and sintering.

The fibrous wollastonite used in the refractory composition for molding of the present invention is a 0aO-3iO crystal that does not contain water of crystallization,
In particular, needle-like crystals are preferred from the viewpoints of heat insulation, strength, and shrinkability. 60a0.6SiO-HO, 25Ca0.6S10.5HO, etc. are not suitable because they shrink when dehydrated due to heating during sintering, and cracks occur when a large monolithic container is manufactured. The blending amount is determined based on the desired bulk density, heat insulation, strength, and workability. When the amount is increased, the resulting product will have better heat insulation properties and less shrinkage, but will have lower strength and workability (fluidity during casting). If the amount is small, the workability and strength will be excellent, but the heat insulation will decrease and shrinkage will increase. For this purpose, the blending amount is 35 to 65% by weight of the total amount with high alumina cement.

When cement is used as a binder to bind wollastonite and harden, it is important that the curing time is appropriate, that it produces sufficient strength, that it has excellent corrosion resistance against aluminum, and that shrinkage due to dehydration is small. required. In response to this requirement, F with an A70 content of 70% by weight or more
'e High alumina cement with low 23 2 O content is suitable. The particle size of cement is generally expressed by the specific surface area using the Blaine method, and the specific surface area is 8.
High alumina cement, which has a relatively small particle size of 000 to 10,000 cm2/g, has a large shrinkage during firing, but has high strength. On the other hand, the specific surface area is 4000
~5ooo (High alumina cement with a relatively large particle size of 1m/g has a small shrinkage during firing, 1, false (Kumeikoma small convexity L → 11, dead / fps agony blade right susu 1 present invention) Then, the specific surface area is 4000-5000 Cn 7g and 8
000 to 10,000 yen/g in weight ratio of 3 to
In a ratio of 6:4, a total of 3 with fibrous wollastonite
The feature is that it is used in an amount of 5 to 65% by weight.

If it is less than 35% by weight, the strength will not be sufficient, and if it exceeds 65% by weight, the bulk density will increase and the heat insulation properties will decrease. In addition, the reason for using high alumina cement with a specific surface area of 4,000 to 5,000 bu/g and one with a specific surface area of 8,000 to 10,000 bu/g at a weight ratio of 3 = 7 to 6:Φ is because of this. This is because, outside this range, the strength may be insufficient or the shrinkage may become large.

The organic binder is added to control casting workability and to prevent pleating phenomenon. As this organic binder,
Carboxymethylcellulose, methylcellulose, polyvinyl alcohol, etc. are selected, but if the amount exceeds 0.5% by weight based on the total of fibrous wollastonite and high alumina cement, the hardening time of the cement will be affected. -to+t'ln1烟1I(dl)l'l/
If J>tpl, 1 p11-gun 1 noka 6 may occur, so this range is set.

By blending organic fibers, the kneaded product obtained by adding water to the above compound can be dried for 2 to 3 minutes while preventing shrinkage of the molded product.
You can do it twice as fast. This is thought to be because the capillary-like voids formed between the fibers and the solid particles surrounding them facilitate the evaporation of water to the outside. If the length of the added fibers exceeds 1Qmm, the dispersibility and castability will deteriorate, so it is necessary to use fibers of 1 (lli1 or less).The amount added is the total of fibrous wollastonite and high alumina cement. If the amount exceeds 1% by weight, the dispersibility and castability will deteriorate, and if it is less than 0.01% by weight, no effect will be produced, so the content should be 1 to 0.01% by weight.

〔Example〕

Wollastonite with needle-like crystals (apparent diameter 10~507j+
n average 2Q μm, length 100-1000μm 1 average about 30Oμm), high alumina cement [1) (specific surface area 8000-100000R/g, AIo 79% by weight, Oao 18% by weight, Fe00.823 23% by weight), high alumina cement) (II) (specific surface area 4
000-5000 cII&/g, AIo 74% by weight, Ca025% by weight, 3Fe5O12,3% by weight), organic binder (methylcellulose), organic fiber (polypropylene, length 5tnjn)
Add water to the composition shown in the table below, and make an inner size of 1m x 1.
．． It was cast into a bathtub-shaped mold measuring 5m x 0.6m. After both AXB were placed in the mold for 4 hours, A was heated to 800C over 48 hours after drying, held at 5ootZ' for 4 hours and fired, and B was heated to 800C over 72 hours after drying. The mixture was heated and held at 800C for 4 hours for firing.

Reference Example (1) used the same formulation as Example 1, and was kneaded, cast, and fired in the same manner.

The corrosion resistance test for these against molten aluminum was 65 x 65 x 11! Cut out a piece of (mm) and make a hole with a diameter of 39 mm and a depth of 70 mm in the center. Put 1 type of aluminum secondary metal into QQ g each, and 7 in 30 minutes.
The test piece was heated to 0.000C, held at 700C for 200 hours, and after cooling, it was divided into two parts and the contact surface between the aluminum and the test piece was observed. As a result, there were no reaction products.

In Reference Example (2), G indicates a conventional commercially available calcium silicate plate, and H indicates the physical properties of a similarly commercially available lightweight castable.

〔Effect of the invention〕

As shown in C of Reference Example (1), if wollastonite exceeds 65% by weight of the total weight of high alumina cement, the strength will decrease even if high alumina cement with high developed strength is used, and as shown in D If high alumina cement with high developed strength is used alone, a product with high strength will be obtained, but the shrinkage will be large.As shown in E-2, if high alumina cement with low shrinkage is used alone, the shrinkage will be small but the strength after firing will be small. . Further, as shown in F, when the total amount of high alumina cement exceeds 65% by weight of the total amount including wollastonite, the bulk specific gravity becomes large, resulting in poor insulation properties and cracks.

On the other hand, according to the refractory composition for molding of the present invention, it is possible to easily produce large molded products that have both heat insulation properties and strength, do not generate cracks, and are corrosion resistant to aluminum and aluminum alloy molten metal. By incorporating fibers, the time required for firing can be shortened compared to when fibers are not incorporated, making it possible to produce the product economically.

Claims (2)

[Claims] (1) Fibrous wollastonite is 35 to 65% by weight of the total of the high alumina cement in ■, and ■The specific surface area by the Blaine method is 4000 to 5000 (the ratio of B 7g of high alumina cement to the Blaine method) Surface area is 8000 ~
(b) 35 to 65% by weight of the total amount of fibrous wollastonite (■) at a weight ratio of 37 to 6:4 with mina cement;
A refractory composition for molding comprising an organic binder in an amount of 0.1 to 0.5% by weight based on the total amount. (2) ■ Fibrous wollastonite is added to the high alumina cement in an amount of 35 to 65% by weight of the total of ■ high alumina cement, and ■ high alumina cement with a specific surface area of 4,000 to 5,000 2/g by the Blaine method is added to the high alumina cement using the Blaine method. Specific surface area is 8000~1
0000 C1n 7g of high alumina cement in a weight ratio of 3 = 7 to 6:4, 35 to 65% by weight of the total with ■ fibrous wollastonite, organic binder in an amount of ■■ Divide 0.1 to 0.5% by weight/Length lQmm
The following organic fibers are divided into 1 to 0.01 to the total.
% by weight, a refractory composition for molding.