JP2009001462A - Shaped refractory and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve slag infiltration resistance, thermal spalling resistance and hot strength, in relation to a shaped refractory having a carbon bound structure formed using pitch and phenolic resin together and a method for producing the same. <P>SOLUTION: A shaped refractory of the invention contains pitch and phenolic resin having a softening initiation temperature difference within 100°C and a solidification temperature difference within 300°C in a total amount of 5-15 parts by mass based on 100 parts by mass of refractory aggregate in such a way that the mass ratio of the pitch to the phenolic resin is made 0.5-10.0. The shaped refractory has a mosaic-like carbon bound structure formed by carrying out heat treatment at a temperature above the lower one of solidification temperatures of the pitch and phenolic resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shaped refractory and a manufacturing method thereof, and in particular, corrosion resistance, slag lubrication resistance, heat spalling resistance, and hot strength used for lining of various kiln furnace facilities used in the steel industry. The present invention relates to a shaped refractory having excellent resistance and a method for producing the same.

  Conventionally, a refractory formed with a carbon bond structure using an organic binder is superior in slag infiltration resistance and heat spalling resistance compared to a refractory formed with a ceramic connective structure. It has been used for a wide range of refractory materials such as chaotic cars, converters, ladles, vacuum degassing equipment, and nozzles for continuous casting. However, since refractories using these organic binders bond with carbon during heat treatment during firing or during use, a sufficient carbon bond structure cannot be formed depending on the type of organic binder and the firing temperature. However, it has a drawback that high hot strength cannot be obtained.

  In order to eliminate such drawbacks, for example, Patent Document 1 discloses that the volatile content is 20 to 60 wt.% With respect to 100 wt. Parts of the composition comprising 60 to 95 wt.% Of the refractory raw material and 5 to 40 wt. % Powder pitch is added in an amount of 0.3 to 5 parts by weight as an outer portion, and 2 to 7 parts by weight of a pitch that is liquid at room temperature as a binder is added and mixed. The pitch of the outer pitch is 0.3 parts by weight or more, the phenolic resin is 6.7 parts by weight or less, and the total of the liquid pitch and the phenolic resin is added and blended in an amount of 2 to 7 parts by weight. A dense-structured carbon-containing refractory with a pitch added to suppress the occurrence of cracks during temperature rise in an actual furnace has been proposed.

  Further, for example, Patent Document 2 discloses that magnesia-based, spinel-based, and alumina-based refractory raw material powders with 5% by mass or less of fullerene carbon as an outer layer, together with a thermosetting organic resin as an organic binder, pitch After adding 0.5-5% by mass, the mixture is kneaded, molded, and heat-treated, and carbon nanofibers having a diameter of 5 to 10 nm and a length of 100 to 300 nm are present in the connective tissue. Carbon-containing refractories have been proposed that have both high strength and thermal shock resistance, can maintain excellent slag penetration resistance, and have sufficient durability.

JP-A-7-53254 JP 2006-8504 A JP-A-5-124873

  Here, in general, the phenol resin is not liquefied by heating, so that the growth of the carbon hexagonal network plane is difficult and the carbon has an optically isotropic structure. On the other hand, since the pitch is carbonized after changing from the solid phase to the liquid phase with heating, the carbon hexagonal network plane becomes carbon having an optically anisotropic structure in which the plane is oriented in a certain direction. Carbon bonds with texture can be obtained. An isotropic carbon bond is dense and therefore can be expected to exhibit high hot strength, but the strength cannot be improved as expected due to poor adhesion to refractory particles. Moreover, since it is dense, it is inferior in spalling resistance. On the other hand, carbon bonds having anisotropy are easily cracked during firing and heating and have good spalling resistance, but cause not only a decrease in density but also a decrease in strength.

  On the other hand, in the proposals of Patent Document 1 and Patent Document 2 in which phenol resin and pitch are used in combination, two structures are formed, an isotropic structure made of phenol resin and an anisotropic structure made of pitch. Although the strength of the phenolic resin can improve the strength in the intermediate temperature range, the effect of improving the corrosion resistance, spalling resistance and hot strength is small. Due to the lack of, the structure is divided, and excellent durability cannot be obtained. Therefore, as in the refractories described in Patent Document 1 and Patent Document 2, even if a phenol resin and pitch are simply used in combination, only one connective tissue is preferentially expressed, and isotropic. There is a problem that a synergistic effect due to the connective structure of the structure and the anisotropic structure cannot be obtained.

  On the other hand, for example, in Patent Document 3, for a refractory aggregate of 100 wt%, pitch and phenol resin having a melting point temperature difference of 100 ° C. and a solidification temperature difference of 300 ° C. or less are used. Is 0.3 to 12.5, and an amorphous refractory with 5 to 25 wt% of outer shell added in the total amount is proposed.

  In this Patent Document 3, a pitch resin having the above characteristics and a phenol resin are blended at a specific weight ratio, whereby the phenol resin becomes a nucleus, and a chained ring of pitches is condensed around the nucleus, thereby causing a mosaic structure. It is said that a carbon connective structure having s is formed in the refractory.

  However, the amorphous refractory of Patent Document 3 is not sufficiently disclosed about the control of carbon bond structure, that is, a specific method for forming a carbon bond structure having a mosaic structure, such as by phenol resin. The synergistic effect due to the connective structure between the isotropic structure and the anisotropic structure due to the pitch cannot be expressed sufficiently. In particular, it is considered that the formation of a mosaic carbon bond structure is greatly influenced by the heat treatment conditions for forming a liquid phase, but Patent Document 3 hardly discloses the heat treatment conditions.

  Moreover, since the refractory described in Patent Document 3 is an indeterminate refractory for pouring, it has good fluidity. On the other hand, in order to obtain a fixed refractory material, it is necessary to press-mold the raw material refractory material and then fire it. When softened during this firing, the pressure-molded material is deformed. Therefore, it is important that the fluidity is not exhibited as much as possible during firing.

  Therefore, the present invention has been made in view of such problems, and in a shaped refractory material in which a carbon connective structure is formed by using pitch and a phenol resin in combination, and a manufacturing method thereof, the corrosion resistance, slag infiltration resistance, The object is to improve the poling property and hot strength.

  As a result of intensive studies to solve the above problems, the inventors of the present invention blended a pitch having a predetermined softening start temperature difference and a solidification temperature difference and a phenol resin at a predetermined blending ratio, and this pitch and phenol are mixed. It has been found that a large amount of carbon bond structure having a mosaic structure can be formed in the connective structure of the refractory by heat treatment at a temperature equal to or higher than the lower solidification temperature among the resins.

  In addition, the inventors of the present invention control the flow rate of the refractory by controlling the blending ratio of the pitch and the phenol resin to a predetermined value, and do not soften and deform during firing after pressure forming of the refractory material. It has been found that refractories can be obtained.

  Based on the above findings, the present inventors have completed the present invention.

  That is, according to the present invention, a pitch and a phenol resin having a softening start temperature difference of 100 ° C. or less and a solidification temperature difference of 300 ° C. or less are mixed at a pitch mass ratio of 0.5 to 10 with respect to the phenol resin. 0.05 or less with respect to 100 parts by mass of the refractory aggregate, 5 to 15 parts by mass in total, and heat treatment is performed at a temperature equal to or higher than the lower solidification temperature of the pitch and the phenol resin. A shaped refractory having a mosaic carbon connective structure formed thereby is provided.

  Further, according to the present invention, a pitch and a phenol resin having a softening start temperature difference of 100 ° C. or less and a solidification temperature difference of 300 ° C. or less are mixed at a pitch mass ratio of 0.5 to 10 with respect to the phenol resin. 0.05 or less with respect to 100 parts by mass of refractory aggregate, 5 to 15 parts by mass in total is added, and pressurized after kneading a refractory material containing phenolic resin, pitch and refractory aggregate There is provided a method for producing a shaped refractory, which is molded and heat-treated at a temperature equal to or higher than the solidification temperature of the lower one of pitch and phenol resin.

  According to the present invention, in a regular refractory material in which a carbon bond structure is formed by using pitch and a phenol resin together, and a manufacturing method thereof, a thermoplastic pitch and a phenol resin are used in combination as a carbon binder of the refractory, and both are solidified. By performing the heat treatment at a temperature equal to or higher than the lower solidification temperature, the mosaic carbon structure can be sufficiently developed. At this time, since the pressure-molded refractory material has low fluidity, it does not soften and deform during firing. Therefore, according to the present invention, by forming a sufficient amount of mosaic connective structure in the refractory, the corrosion resistance, slag infiltration resistance, heat spalling resistance, and hot strength of the regular refractory are greatly improved. Can be made.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Structure of the regular refractory according to the present invention)
The regular refractory according to the present invention has a mosaic carbon structure formed in the connective structure of the refractory. The mosaic structure referred to in the present invention is an anisotropic unit in which the generated carbon hexagonal network plane is oriented in a small region, and is a carbon connective structure in which they are randomly assembled. Compared with a strong binding force.

  Here, the generation mechanism of the carbon bond structure (hereinafter, also referred to as “mosaic structure”) having the mosaic structure of the present invention will be described in detail.

  The mosaic structure of the present invention uses a thermoplastic pitch and a phenol resin together as a binder for a refractory aggregate, forms a liquid phase by heat treatment, and then has a large optical anisotropic unit size in the carbonization and solidification process. By forming this mosaic structure, it is possible to improve the hot strength of the regular refractory. Hereinafter, the results of the examination by the present inventors on the conditions for forming such a mosaic structure will be described.

  The present inventors first confirmed the carbon bond structure obtained by heat-treating each of pitch and phenol independently. When a phenol resin is used alone as the binder, for example, the phenol resin is heated at a rate of 8 ° C./min, held at 1000 ° C. for 1 hour, and then slowly cooled to provide an isotropic carbon bond. The organization was found to be obtained. The connective structure obtained from this phenol resin is an optically isotropic structure and is a structure having a glassy structure. On the other hand, when pitch is used alone as a binding material, for example, the pitch is heated at a rate of 8 ° C./min, held at 1000 ° C. for 1 hour, and then slowly cooled, whereby carbon bonds having anisotropy are obtained. The organization was found to be obtained. The connective structure obtained by this pitch is an optically anisotropic structure, and is a flow structure. In addition, it can confirm that these structures | tissues are formed, for example by observing with a reflective microscope etc. of magnification 1000 times.

  Next, when pitch and phenol resin are used together as a binder for the fireproof aggregate, for example, pitch and phenol resin are mixed at a mass ratio of 1: 3 and heated at a rate of 8 ° C./min. It was found that a mosaic structure in which anisotropic units in which the carbon hexagonal network plane according to the present invention was oriented in a small region was randomly gathered was formed by holding at 1000 ° C. for 1 hour and then slowly cooling.

  The pitch used in the present invention is, for example, a fixed carbon amount of about 40 to 60% by mass, a melting point of 120 ° C. or less, and a solidification temperature of 450 to 550 ° C., and used as a refractory binder. Especially, the melting point is low. On the other hand, the phenol resin used in the present invention has, for example, a number average molecular weight of 200 to 300, a melting point of 70 ° C. or lower, and a solidification temperature of 250 to 400 ° C., and is usually used as a refractory binder. The resin has a low melting point and a high solidification temperature.

  From the above facts and examinations, the present inventor presumed the generation mechanism of the mosaic structure by the combined use of pitch and phenol resin as a binder as follows. Depending on the pitch of the thermoplastic and phenolic resin, each of the pitch and the phenolic resin starts softening and melting at a temperature of 50 to 300 ° C. by receiving heat during firing, and oxygen at a temperature of 400 to 600 ° C. Atoms other than carbon, such as hydrogen, leave and carbonize and solidify. Further, atoms other than carbon are not recognized at a temperature of 800 ° C. or higher, and a carbon bond structure is formed. As described above, the pitch is a structure of an optically anisotropic flow structure in which the carbon hexagonal network plane is oriented in a certain direction, while the phenol resin is optically isotropic because it does not polycondensate. It becomes the structure of the glass structure. However, when both are used in combination, since both are softened and melted and compatible, the carbon bond structure finally formed differs depending on the difference in the start of carbonization and solidification.

  That is, if the phenol resin that forms the connective structure of the glass structure with no flow solidifies first, and the pitch that forms the connective structure of the flow structure solidifies later, the phenol resin that has solidified first becomes the nucleus, and the flow of the pitch A mosaic structure is formed in which three-dimensionally messed up. In order to form a large amount of this mosaic structure in the connective tissue and to obtain a high hot strength, the softening start temperatures of the two and the phenol resin are approximately equal so that the pitch and the phenolic resin are compatible when softened and melted. In order to prevent the formation of the isotropic structure and the formation of the isotropic structure from the phenol resin separately, it is necessary that the solidification temperatures of the both be close to some extent.

  FIGS. 1 to 3 show reflection micrographs of the mosaic structure obtained as described above, the flow structure with a pitch alone, and the glass structure with a phenol resin alone. FIG. 1 is a drawing of a mosaic structure (coarse mosaic structure having optical anisotropy by the pitch / phenolic resin of the present invention), and FIG. 2 is a glassy structure (optically formed by a phenolic resin or the like). FIG. 3 is a drawing of a flow-like structure (an optically anisotropic flow structure formed by a pitch).

  From the formation mechanism of the mosaic structure as described above, the present inventors, as a refractory aggregate binder for obtaining the mosaic structure of the present invention, has a softening start temperature difference within 100 ° C. and a solidification temperature. It has been found that it is necessary to select a pitch and a phenol resin whose difference is within 300 ° C. When the difference in melting point between pitch and phenolic resin exceeds 100 ° C, they are not compatible when softened and melted, and when the difference in solidification temperature between pitch and phenolic resin exceeds 300 ° C, anisotropy due to pitch Since the formation of the sex tissue and the formation of the isotropic tissue by the phenol resin are performed separately, the above-described mosaic structure is not formed. The difference in solidification temperature between pitch and phenol is preferably within 200 ° C.

  In order to increase the formation amount of the mosaic structure, the carbonization start temperature of the phenol resin is lower than the carbonization start temperature of the pitch, and the phenol resin starts carbonization and solidification first. Preferred for complete prevention. When the pitch solidifies faster, the flow structure tends to be a main structure, and the formation amount of the mosaic structure may be reduced.

  In the present invention, the softening start temperature of pitch and phenol resin can be measured by JIS K2207 (ring and ball method). The solidification temperature of pitch and phenol can be measured by JIS M8801 (Gieseller blast meter method).

  As will be described later, the amount of pitch and phenol resin added is the sum of the pitch and phenol resin in which the ratio of the mass of the pitch to the mass of the phenol resin (Pi / Ph) is 0.5 or more and 10.0 or less. It is preferable that it is 5-15 mass parts with respect to 100 mass parts of fireproof aggregates.

  If the total amount of pitch and phenol resin is less than 5 parts by mass, the amount of fixed carbon in the refractory is too small, and the corrosion resistance is inferior. On the other hand, if the total amount of pitch and phenolic resin exceeds 15 parts by mass, the gap between the binder and the particles of the refractory aggregate becomes large, the phenomenon of detachment of the refractory aggregate becomes remarkable, and as a refractory This is not preferable because the uniformity and stability of the tissue is significantly reduced.

  The mass ratio (Pi / Ph) between the pitch and the phenol resin needs to be 0.5 or more and 10.0 or less. Hereinafter, this reason will be described.

  The present invention is a regular refractory material obtained by subjecting a raw material refractory material (a refractory aggregate, a binder, other additives, etc.) to pressure forming and then heat treatment (firing). Therefore, when firing the refractory material after pressure molding, if the refractory material is softened, the pressure molded material will be deformed. It is important to keep it low. Thus, as a result of investigations by the present inventors, it was found that the fluidity of the refractory raw material during firing can be suppressed by setting Pi / Ph to 0.5 to 10.0. That is, the mass ratio (Pi / Ph) between pitch and phenol used in the shaped refractory of the present invention needs to be 0.5 or more and 10.0 or less, preferably 1.0 or more and 8. 0 or less.

  Here, for example, in the refractory described in Patent Document 3 described above, the upper limit of the allowable value of the weight ratio of pitch to phenol (corresponding to Pi / Ph of the present application) is 12.5. With such a large value, the fluidity of the refractory material becomes too large during firing and deformation occurs, so that the refractory material cannot be formed into a desired shape. On the other hand, since the refractory of the present invention is a fixed refractory and needs to be formed into a desired shape, it is essential to set Pi / Ph to 10.0 or less. Moreover, when Pi / Ph exceeds 10.0, a lot of pitch flow structures appear, and a sufficient mosaic structure does not develop, so that the hot strength cannot be achieved and the wear resistance is inferior. The corrosion resistance cannot be improved.

  On the other hand, when Pi / Ph is less than 0.5, a glassy structure of phenol resin appears in a large amount even when sufficient molding pressure and heat treatment are applied, and a sufficient mosaic structure does not develop. Cannot be improved. Therefore, Pi / Ph needs to be 0.5 or more.

  In order to form a mosaic structure in the regular refractory of the present invention, after adding pitch and phenol resin having the above-described physical properties in the above-described mass ratio and addition amount, the pitch or phenol resin is solidified at a lower temperature. It is necessary to heat-treat at a temperature higher than the solidification temperature. When the heat treatment temperature is lower than the solidification temperature of the lower pitch or phenol resin, sufficient carbonization has not started and volatile components remain, so that cracks are induced or the strength is insufficient when using refractories. May occur. Specifically, heat treatment is preferably performed at a temperature of 800 ° C. or higher. By performing heat treatment at such a temperature, a carbon connective structure having a mosaic structure can be sufficiently grown.

  The types of refractory aggregates used in the shaped refractories of the present invention include basic materials such as magnesia, magnesia-chromium, magnesia-calcia, dolomite, alumina, spinel, and zircon. In addition, neutral raw materials such as silica-based materials and acidic raw materials can be mentioned, and non-oxide-based raw materials include carbon raw materials such as earth graphite, natural graphite, carbon black, coke, silicon carbide, silicon nitride, boron carbide, Examples thereof include boron nitride.

  In the present invention, various metals (for example, Al, Si, etc.) can also be used as the antioxidant.

(Method for producing a shaped refractory according to the present invention)
The structure of the regular refractory according to the present invention has been described above. Hereinafter, a method for manufacturing the regular refractory having the above-described structure will be described in detail.

  In the method for producing a shaped refractory according to the present invention, first, as a refractory raw material, a refractory aggregate, a binder containing pitch and phenol resin, and an additive such as an antioxidant as necessary are added. As described above, the pitch and the phenol resin added as the binder are those having a softening start temperature difference of 100 ° C. or less and a solidification temperature difference of 300 ° C. or less, and a mass ratio between the two (Pi / Ph). Is 0.5 to 10.0 and is kneaded while adding a total amount of 0.5 to 15 parts by mass with respect to 100 parts by mass of the refractory aggregate, and pressure-molded at a pressure of 50 to 200 MPa. Thereafter, heat treatment (firing) is performed at a temperature (for example, 800 ° C. or higher) equal to or higher than the lower solidification temperature of the pitch and the phenol resin. As a result, a regular refractory having a mosaic structure as described above can be obtained.

  Here, the heat treatment is preferably performed for 3 hours or more. When the heat treatment time is less than 3 hours, a mosaic structure effective for bonding is not sufficiently developed, which is not preferable.

  As described above in detail, by firing the pressure-molded refractory raw material at a temperature equal to or higher than the lower solidification temperature, by forming a mosaic carbon bond structure in the refractory bond structure, It has high hot strength and can provide excellent durability under conditions of vigorous stirring of molten steel. Moreover, it can prevent that the refractory raw material pressure-molded at the time of baking softens and deforms by making mass ratio (Pi / Ph) of pitch and phenol resin into 0.5 or more and 10.0 or less.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  As shown in Table 1 below, a refractory material having a predetermined composition and an antioxidant (metal Al or metal Si) are mixed with a pitch having a predetermined physical property and a phenol resin by changing the mass ratio (Pi / Ph). What was added was kneaded and pressure-molded at a pressure of 60 MPa. Thereafter, heat treatment was performed at the maximum temperature (° C.) shown in Table 1.

  Next, the hot bending strength (MPa) at 1450 ° C., the corrosion resistance index, and the generation area ratio (%) of the mosaic structure of the regular refractory thus obtained were measured.

  In this example, the hot bending strength was measured according to JIS R2213.

  Moreover, about the corrosion resistance in a present Example, each test material was tested at 1700 degreeC for 5 hours by the rotary erosion method using the converter slag, and the erosion dimension was measured. The measured erosion dimension was indexed with the erosion dimension of the specimen of Comparative Example 1 as 100.

  In addition, the generation area ratio of the mosaic structure in the present example was an area ratio of the tissue structure part in which small hexagonal mesh surfaces are gathered with slightly different orientations in one field of view in the reflection micrograph. Moreover, the measurement of the production | generation area ratio of a mosaic structure | tissue calculated the area ratio defined above by performing image analysis using a reflection micrograph.

  Table 1 shows the results of hot bending strength (MPa), corrosion resistance index, and mosaic structure formation area ratio (%) measured at 1450 ° C. as described above.

  As shown in Table 1, it was confirmed that Examples 1 to 7 as examples of the present invention were superior to Comparative Examples 1 to 6 as conventional examples in both hot bending strength and corrosion resistance. This is considered that in Examples 1 to 7, the mosaic structure was sufficiently generated in the carbon connective structure by adopting the configuration of the present invention.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is a drawing of a reflection micrograph of an example of the mosaic structure of the present invention. It is a drawing of a reflection micrograph of an example of a glassy structure. It is a drawing of a reflection micrograph of an example of a flow-like structure.

Claims (2)

Pitch and phenol resin having a softening start temperature difference within 100 ° C. and a solidification temperature difference within 300 ° C. so that the mass ratio of the pitch to the phenol resin is 0.5 or more and 10.0 or less. In addition, with respect to 100 parts by weight of the fireproof aggregate, the total amount includes 5 to 15 parts by weight,
A shaped refractory material having a mosaic carbon bond structure formed by heat treatment at a temperature equal to or higher than the solidification temperature of the pitch and the phenol resin which is lower than the solidification temperature. Pitch and phenol resin having a softening start temperature difference within 100 ° C. and a solidification temperature difference within 300 ° C. so that the mass ratio of the pitch to the phenol resin is 0.5 or more and 10.0 or less. In addition, 5 to 15 parts by mass in a total amount is added to 100 parts by mass of the refractory aggregate,
After kneading the refractory material including the phenol resin, the pitch and the refractory aggregate, press molding,
A method for producing a shaped refractory, characterized in that heat treatment is performed at a temperature equal to or higher than the solidification temperature of the pitch and the phenol resin, which is lower than the solidification temperature.

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