Compositions: ceramic – Ceramic compositions – Refractory
Patent
1996-11-04
1998-03-24
Marcheschi, Michael
Compositions: ceramic
Ceramic compositions
Refractory
524 59, 524 66, 524876, 524877, 524904, 523145, C04B 3500
Patent
active
057312494
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of international application number PCT/JP95/02042, filed Oct. 5, 1995.
FIELD OF THE INVENTION
The present invention relates to a spray-on (gunning) refractory composition used for furnace wall, furnace bottom, etc. of steelmaking facitilities such as a ladle, converter, electric furnace, and in particular, to a spray-on refractory composition having high service life, adhesive property and corrosion-resistant property.
BACKGROUND ART
In the past, as spray-on (gunning) refractory composition used for repair of a furnace wall, furnace bottom etc. of steelmaking facilities such as a converter, electric furnace, ladle, etc., a composition has been known which contains an inorganic binder such as phosphate or silicate added to refractory aggregate by 3 to 10 weight %. However, this conventional type composition is disadvantageous in that the service life is not sufficient when exposed to severe operating conditions of the steelmaking furnaces.
The disadvantages may be attributed to the facts that the inorganic binder forms substances of low melting point when heated and bonded and causes shrinkage, that the binder migrated as water is rapidly evaporated because it is used in aqueous solution and adhesive strength is reduced and the binder is separated, and further, that it is easily dissolved and service life is reduced because inorganic binder contains much liquid phase in the matrix.
Further, a refractory composition is known which is obtained by adding an inorganic binder such as phosphate or silicate by several weight % and an organic binder such as pitch, phenolic resin, etc. by 10 weight % refractory aggregate. The composition of this type is also disadvantageous in that the above problems are not solved yet because the inorganic binder exerts extensive influence on the adhesive property. Also, in case phenolic resin is used as the organic binder, it often hinders adhesive performance of the inorganic binder and the refractory composition is very likely to drop or strip off. Further, carbon generated by carbonization of the organic resin is oxidized by alkali components of the inorganic binder, and this reduces the favorable effect of carbon.
Further, another type of refractory composition is known, which is produced by adding pitch or novolak type phenolic resin to refractory aggregate, whereas this is also disadvantageous in that it flows down along high temperature furnace wall during heating and bonding, and it has no sufficient adhesive property and is not usable as a spray-on refractory composition.
There is also a castable (prepared unshaped) refractory using phenol-formaldehyde type resin. For example, Japanese Patent Publication 62-38382 discloses a method to use only powder of the above resin added to inorganic material powder as a binder, or a method to obtain a binder by combining water-soluble organic binder, auxiliary forming agent, petroleum product and its byproducts as auxiliary components for the binder. These methods are disclosed for applications as wall material fire-retardant paint, fire-retardant pad, etc. of a blast furnace, converter, etc. In case the mixture of these inorganic material powders is used as a spraying material and if only phenol-formaldehyde type resin is used for the binder, warping occurs on the portion of the facilities to be sprayed, and there is also problem in adhesive property. Also, in case it is used as auxiliary component other than pitch with high melting point, fluidity and form-keeping property are not sufficient as spraying material, and the adhesive property is lower and it runs down. When the petroleum type auxiliary component is added, adhesive property cannot be improved and warping of the portion to be sprayed is not prevented.
It is an object of the present invention to provide a spray-on (gunning) refractory composition, which is high in anti-stripping property, adhesive strength and corrosion-resistant property and is suitable for high temperature operation in steelmaking furnaces.
DISCLOSURE OF THE INVENTION
REFERENCES:
patent: 4102694 (1978-07-01), Sasaki et al.
patent: 4427800 (1984-01-01), Nakamura et al.
patent: 4501836 (1985-02-01), Nakamura et al.
Matsuda Tasuku
Sugimoto Hiroyuki
Takenaka Hiroshi
Tanaka Koichi
Marcheschi Michael
Shinagawa Refractories Co. Ltd.
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