JPS5826079A - Heat resistant castable blend - 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 heat-resistant castable formulations, particularly heat-resistant castable formulations with high room temperature strength.

Castable refractories are not only widely used as materials for various kilns because they are easy to construct and can be used in a relatively short period of time after construction, but in recent years, they have been used not only for kilns but also for those with fairly complex shapes and It has also been used as an effective lining for specialty products such as ceramic lining for pipes.

The present invention was developed primarily as a refractory material with a fixed shape such as a pipe, which can be used immediately after heat treatment and has properties that are sufficiently durable for use. It is also effective as a castable refractory for use in kilns.

Conventional castable refractories use alumina cement as a binder phase, and due to the low melting point of alumina cement (approximately 1,550 to 1,600°C), the high-temperature strength #'' of castable refractories is not sufficient. There wasn't.

In order to solve this point, alumina cement buttock: i
Various efforts have been made to reduce the pk of alumina cement, such as by adding a small amount of v $ U, and although these methods have some effectiveness, they are not suitable for use as aggregates. - Some people are not yet ready to wear a pair of shoes.

Therefore, the present inventors conducted repeated research in order to achieve greater high-temperature strength, which has not yet been found in castable rice grains, and as a result, they arrived at the present invention. Ceramic ultrafine powder

That is, one feature of the present invention is that strontium aluminate cement, which has not been used conventionally, is used as an aggregate and O). Another special benefit is the use of ultrafine powder.

Strontium aluminate id', SrO-Al2
O3.

Compounds such as SrO-2A1zO3, Sr0 ・6A120s are known, and all of them are similar to conventional alumina cement (calcium monoaluminate) OmA1550-1.
This is much higher than 600℃.

The present inventors have conducted sufficient research on the water hardening of strontium aluminate, and have discovered that it can be preferably used as a binder phase for aggregates in the form of cement. It was accomplished.

Strontium aluminate is 3SrO-
A12os ・6HzO, Al(OH)3 and SrCO
3, 3SrO-Adzes-6HxO and A1
(O sub-2 is thought to have a binding effect.

Thus, water utilization hardening 3SrO・Al2O3-6H2
0 and Al (OH), k Mg combined phase, as the castable molded body is heated, all crystallization water is released, and most of it is re-fjj 5rO-A120s, Sr0
・2A1203, Sr0 ・6A120+ or F3rO and Al2O produced when these react with aggregate
It becomes a crystalline phase containing 3.

In addition to using the above-mentioned strontium aluminate cement as a binder phase, the present invention requires that ultrafine ceramic powder of 01 μm or less be blended therein.

This ultra-fine powder has the effect of adjusting the curing time of the strontium aluminate cement, particularly shortening it, and at the same time reducing the f of the strontium aluminate cement required to achieve the desired strength of the castable molded body after hardening. have an effect.

The former effect of this ultra-fine powder is that after pouring the cast or tuple mixture into the mold, the time until it becomes possible to split the mold can be shortened, especially when casting items with irregular shapes. Since the mold rotates easily, it requires fewer expensive molds. The latter effect of this Mh powder, which is particularly important for the present invention, reduces the amount of strontium aluminate that is relatively expensive to use, and at the same time reduces the amount of strontium interposed between aggregate particles. As the aluminate y decreases, the strength at high temperatures increases significantly.

In the present invention, the effect of adding the ultrafine ceramic powder is as described above, but the particle size of the ultrafine powder must be 01 μm or less, preferably 0.05 μm or less. The mechanism of the effect of this ultrafine powder has not yet been fully elucidated, and the reason for limiting the particle size of this ultrafine powder as described above has not been fully elucidated. This is because if the particle size of the powder exceeds 0.1 μm, it will not have a significant effect on accelerating the hardening of strontium aluminate. It's a shame, the particle size of this ultra-fine powder is 0.
If it is 1μ or more, the effect of reducing the amount of strontium aluminate required to obtain the desired strength seems to be weakened.

For the reasons mentioned above, it is necessary that the ultrafine ceramic powder used in the present invention has a particle size of 0.1 μm or less;
Furthermore, it is preferable that the amount of this ultrafine powder is 1 to 17% by weight based on the total amount including the aggregate and strontium aluminate cement. More preferably, this range is 35 to 12% by weight.

The reason for this is that if the content of this ultrafine powder is more than 17% by weight, it may hinder the development of strength due to hardening of the strontium aluminate, which is undesirable.
This is because if it is less than 1 weight ratio, the effect of accelerating the hardening of strontium aluminate cement will be small.

In addition, the blending ratio of the strontium aluminate cement is preferably 05 to 25% in the total amount of the strontium aluminate cement.
The content is preferably 10% by weight. The reason for this is that if the amount is less than 0.5% by weight, the amount is insufficient to bind the bone phase, and therefore the gL degree of the castable molded product will be insufficient.If it is more than 10% by weight, the castable molded product will certainly This is because the strength at room temperature is improved, or the strength at high temperature cannot be expected to be improved.

In order to obtain a castable molded body using the composition of the present invention, water is added for the water utilization reaction of the strontium aluminate cement, but if it is too small, the water utilization reaction of the strontium aluminate cement will be insufficient, resulting in a castable molded body. The strength of the water becomes opaque, and if the water is removed too much, there will be too much water in the drying process, which will increase the amount of agglomeration during firing. It is desirable that the amount is in the range of 3 to 20% by weight, preferably 3 to 15% by weight based on the total amount.

Next, the ultrafine ceramic powder and aggregate used in the present invention will be explained.

The ceramic ultrafine powder is not particularly limited as long as the particle size is OIμ or less, but according to the research of the present inventor, silica,
It has been found that alumina, chromium oxide, titanium dioxide, zirconia, and zircon are effective in terms of the effects of the present invention.

Regarding the aggregate, when used as a refractory, ceramic grains with a slightly larger particle size, for example, about 1000 to 3000μ, can be used, and in the case of fine ceramics for pipes, rolls, etc., a slightly finer particle size, such as 100 to 600μ, can be used. Ceramic powder of about 100 ml is used. The chemistry of these aggregates is not limited to bamboo, but according to the research of the present inventors, carbonized F+ = elemental,
A nitrided paper can be suitably used.

In the composition of the present invention, it is possible to use various additives according to necessity.
In order to obtain favorable shape properties, a viscosity modifier is preferably added, and this may be carboxymethyl cellulose, polyvinyl alcohol, etc., which are generally known for that purpose.

The composition I of the present invention is constructed as described above, and can achieve its purpose by being cast into a mold of a predetermined shape, and will be further explained in Examples below.

Example: A mixture of equimolar amounts of strontium carbonate powder and alumina powder was thoroughly mixed and molded using a mechanical press.
It was baked at 0°C for 5 hours. This was powdered to an average particle size of 45μ. When this fired powder was examined by X-ray diffraction, SrO・A
12oz, Sr0・2A120a and Sr0・6
It was A1203.

The strontium aluminum powder thus obtained, the heat-resistant aggregate shown in No. 18, the ultrafine ceramic powder,
4X4X]617
It was placed in a 7+ all-pole mold to undergo a curing reaction (the curing reaction time was >J', also listed in Table 1). Next, this molded body was removed from the mold, and its room temperature and high temperature strengths were measured.

Comparative examples with conventional alumina cement are also listed in Table 1.

Procedural Amendment February 23, 1980 Mr. Tosaka Shimada, Commissioner of the Patent Office”° Case 0 Display Special Ass 6-0246% 3 No. 2
Invention (J name Heat Resistance Yaya, < p 7' /l/
Formulation 3, relationship to the case of the person making the amendment Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name
(004) Asahi Glass Co., Ltd. 6, Detailed description of the invention in the specification subject to amendment

Claims (1)

[Scope of Claims] (1) A heat-resistant castable composition using strontium aluminate cement, which is made by blending ultrafine ceramic powder with a particle size of 0.1 μm or less as a hardening modifier, as a binding material with aggregate. (2) The strontium aluminate cement is 0.5 to 10% by weight in the total amount including the aggregate, and the ultrafine ceramic powder with a particle size of 0 μ or less is in the total amount including the aggregate and strontium aluminate cement. 1-17% by weight in
A heat-resistant castable composition according to claim (1). (8) A heat-resistant castable formulation as claimed in claim (1), wherein the amount of water is 3 to 20% by weight. (4) Ceramic ultrafine powders include silica, alumina,
The heat-resistant castable composition according to any one of claims 1 to 8, which is one or more selected from the group of chromium oxide, titanium dioxide, zirconia, and zircon. (5) The aggregate according to any one of claims (1) to (4), wherein the aggregate is one or more selected from the group of silicon carbide, silicon nitride, alumina, zirconia, and zircon. Heat-resistant castable formulation.