JPS582270A - Sic-containing castable refractories - 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 This invention relates to an improved castable refractory. Demand for castable refractories has been increasing in recent years as a deficient refractory, and significant progress has been made in improving the quality.

For example, one of the conventional typical castable refractories is
Alumina cement as a binder by weight% 10-309
However, since it required a large amount of water, the structure was not very porous, and the strength was not sufficiently developed, especially for hot strength. was restricted. On the other hand, in recent years, castable refractories that are dense and have excellent hot strength have been developed by reducing the amount of alumina cement used and instead adding very fine refractory fine powder as a binding component.

On the other hand, in castable refractories, E
Adding liC (silicon carbide) gives refractories thermal shock resistance and chemical reaction resistance.

It is known that it can be improved and is actually used. However, when SiC-containing castable is used in a high-temperature oxidizing atmosphere, SiC is oxidized and S10
．． This has a negative impact on the construction structure, such as causing expansion and cracking.

On the other hand, by adding metal powder of Fe-8i (ferrosilicon) to this type of castable metal silicon material, these metals oxidize earlier than SiC, preventing the oxidation of 81C and its formation. The object is Si
It is known that C uniformly spreads over the surface, fills the pores in the refractory, prevents oxygen from entering, and further suppresses oxidation of SiC.

However, in castable refractories that use alumina cement, alumina cement is a strong alkaline binder that reacts with water and exhibits TEOH-, which causes S
+ 2H, Si+20H+H10-8in;
This reaction generates H and gas, which not only causes cracks and blisters during the curing and curing of refractories, but also causes explosions during heating and drying even after curing. When this explosion phenomenon occurs in a dense castable having the above-mentioned excellent properties, it becomes even more dangerous.

In view of these points, the present invention was discovered as a result of various research into making full use of the characteristics of castable refractories, which are dense, corrosion resistant, have high hot strength, and have excellent thermal shock resistance. It is something that

That is, in terms of weight percent, the present invention contains 5 to 80% SiC, 1 to 20% refractory ultrafine powder of 1μ or less, and 1% alumina cement.
~7%, pre-coated metallic silicone and/or
Alternatively, the gist is a SiC-containing castable refractory characterized by consisting essentially of 1 to 5% ferrosilicon powder and the remainder refractory aggregate.

According to the present invention, the resin-coated Sl or S
By using i-Fe, the characteristics of castables using alumina cement and castables densified using ultrafine powder are not limited to these binders. It is characterized by making it possible to fully demonstrate.

The refractory aggregate used in the present invention essentially consists of the remainder other than the essential components described below, and in terms of quantity, it is the component that constitutes the majority of the castable of the present invention as aggregate, and is suitable for use of the castable.

Various types can be used depending on the purpose. Specifically, alumina, bauxite, clayey chamotte, silica, silicon nitride, graphite, zircon, etc. are mainly suitable, and the particle size is approximately αO1 to IQ+u+.

Further, the SiC used in the present invention may be blended as a part of the aggregate, for example, as coarse particles, as a part of the joint, for example, as fine powder, or as a part of the aggregate, for example, as a fine powder, or as a part of the aggregate, for example, as a fine powder. They can also be blended.

In addition, the refractory ultrafine powder used in the present invention works with alumina cement to enable excellent bonding and dense castability, and the particle size must be 1μ or less. , although it specifically depends on the selection of aggregate, etc.
Generally, metal oxides such as silica, chromia, titania, zirconia, and alumina, or materials containing these as main components, are preferably used.

Further, as the alumina cement used in the present invention, a normal alumina cement containing carunium aluminate as a main crystal component is sufficient.

Further, as the metal silicon/or ferron silicon used in the present invention, commercially available ordinary metal powder can be appropriately used, but it is necessary to coat the surface with a resin in advance. This prevents the reaction with OH-, which is an alkali ion, and makes the castable of the present invention particularly useful.

Here, the resin coating used for this purpose basically needs to be one that cuts off contact between Sl or Fe-8i and OH-, but it must be heat resistant to a temperature of 100°C or higher at which water evaporates. It is necessary that Si and 81 decompose below the temperature at which they begin to oxidize, and that it also has alkali resistance, no thickening (to prevent agglomeration of refractory grains), and Si.
A product that has the properties of being 810 tons after firing without changing C to Sin, not foaming 81 before heating (does not react with 81 at room temperature), and creating a film as thin and uniform as possible. desirable. Specifically dimethylsilane.

Silicone-containing resin coatings such as sodium methyl siliconate, silicone oil, and silicone resin are optimal, but depending on the conditions, novolazo-type phenol resins, fluorine-based resins, etc. may also be effective.

In addition, metals other than Sl or Fe-8i, such as aluminum powder, have too much activity, making it difficult to obtain a sufficient effect with a thin resin plate, and it is also difficult to form an oxidation prevention film on SiC than with 81 etc. Not enough effect.

In the present invention, the weight ratio of each of these components is as follows. (Weight %) Particularly desirable range SiC 5-80 7-20 Refractory ultrafine powder 1-20 5-15 Alumina cement 1-7 2-5 Resin coating S1 and 'EPe-8i 1-7 2-5 Human bone Material Remainder Remainder (Water; Outer portion) (About 5 to 15) Here, the reason for these restrictions will be explained.

First, if SiC is too small, the thermal shock resistance and chemical reaction resistance of the refractory will not be sufficient, making it difficult to achieve the original purpose, and if it is too large, it will adversely affect the physical properties of the refractory.

If the amount of refractory ultrafine powder is too small, fluidity during casting will be insufficient and a dense, high-strength refractory will not be obtained, while if it is too large, castability and high-temperature physical properties will be adversely affected.

If the amount of alumina cement is too small, it will adversely affect the curing time and the necessary physical properties will not be obtained, while if it is too large, the compactness will be lost and the physical properties and corrosion resistance will be adversely affected.

Also, if the resin coating S1 or Fe-81 is too small, S
It will not be sufficient to suppress the oxidation of iC, and if it is too large, the generated oxides will have a negative effect on the physical properties and corrosion resistance of the refractory, and will cause a decrease in fire resistance and high-temperature strength, as well as an increase in residual expansion. East.

As described above, the present invention has the characteristics of being dense and corrosion resistant, has excellent hot strength and thermal shock resistance, and has the effect of eliminating the risk of cracking, expansion, explosion, etc. of the refractory installed. 4, which made castable refractories possible, and has great industrial value.

The present invention will be further explained with reference to Examples.

Example 1 Aggregate (calcined bauxite) Coarse grains (168~&66wR) 40% medium grains (L
68 tomo or less) 25 Fine particles (01M or less) 8 SiC (α25IIIJI or less) 10 Ultrafine powder/liquid (1μ or less) 10 High alumina cement 5 Si coated with methyl 7 oran 8 Castable fireproof formulations such as The product was piece-molded in a suitable mold, dried and hardened, and then fired. The results are shown in Table 1 in comparison with comparative examples.

Table 1 A 2.76850128 0 No B i6950 145 1) Use untreated 81 A 2.76850 j28 0 Poly B 266950147 1>Poly S1 Additive-free A 2.74840111 0 No B i99B8124100 None (Note) A...110℃ x 2 barrel firing, B...150
0℃×8 hours firing Example 2 Aggregate coarse grain (168~&66M) 40% medium grain (16
89 or less) 20 Fine grains (05 heads or less) 7 iC Coarse grains (611111 or less) 6 Fine grains ((
1151111+1 or less) 10 ultrafine powder (1μ or less) 10% alumina cement 4 Fe-8i4 water whose surface is coated with ricon oil (outer layer)
The results were obtained by treating a formulation like Example 1 in the same manner as in Example 1.
Shown in the table.

Table 2 A 2.797801040 No B 2L77820116 2> None Use of untreated Fe-81 A 2L797801080 B IT’l 8101152) Multi No Fe-Si addition A Z867001000 None B 2.88780.112100 No

Claims (1)

[Claims] 5 to 30% SiC, 1 to 20% refractory ultrafine powder of 1μ or less, 1 to 7% alumina cement, metallic silicon and /' or ferrosilicon powder coated with resin in advance. SIC-containing castable refractories, characterized in that they consist essentially of 1-7% refractory aggregate and the balance