JPH05124873A - Castable refractories - Google Patents

Abstract

(57) [Abstract] [Purpose] A method for producing an amorphous refractory having high hot strength which is excellent in corrosion resistance, spalling resistance, and abrasion resistance by forming a mosaic carbon bond structure. [Composition] As a means for forming a large amount of mosaic carbon bond structure by using pitch and phenol resin together, the melting point temperature difference is within 100 ° C and the solidification temperature difference is within 300 ° C with respect to 100 wt% of refractory aggregate. The pitch and the novolac type phenolic resin of 0.3 to 12.
5. An irregular shaped refractory made by adding 5 to 25 wt% of the total amount and granulating this. [Effect] Since the mosaic carbon bond structure obtained in the present invention is an aggregate of carbon particles, it exhibits fracture toughness and crack propagation resistance of the carbon bond, exhibits excellent spalling properties, and has high hot workability. It has become possible to arbitrarily obtain a structure that is strong and has excellent corrosion resistance and wear resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unshaped refractory having a high hot strength which is excellent in corrosion resistance, spalling resistance and wear resistance and is used for hot repair of the lining of a steelmaking furnace.

[0002]

2. Description of the Related Art Recently, as an amorphous refractory used for hot repair of steel lining furnaces such as converters, ladles, hot metal trucks and vacuum degassing furnaces, recently, pitch, phenolic resin, etc. have been used as binders. A non-aqueous material that has been used is used. It is known that this non-aqueous amorphous refractory is superior in adhesiveness, corrosion resistance, etc., as compared with the conventional water-mixed form in which water is used. However, because these amorphous refractories are used hot, they cannot follow the rapid changes in the furnace temperature due to the timing of construction, construction thickness, heating time, etc., and carbon bonds formed by pitch and phenolic resin. It had a defect that the tissue was not fully developed.

[0003]

It is known that the use of pitch or resin as a binder in an amorphous refractory is effective in improving hot filling and workability. For example, JP-A-56-26777, JP-A-56-109874, and JP-A-57-205381.
As can be seen in the official gazette. JP-A-56-26
According to Japanese Patent No. 777, the use of pitch and thermosetting resin has an effect on the adhesive strength due to the pitch and the adhesiveness due to the hardening action of the thermosetting resin, but has the drawback that there is no hot fluid filling action. Have

In Japanese Patent Laid-Open No. 56-109874, there is provided a repairing material which is a combination of a thermosetting resin and a thermoplastic material and emits less smoke and has a shorter seizure time. However, it is effective only for adjusting the thermosetting time. I can only find it. In addition, JP-A-5
In Japanese Patent Laid-Open No. 7-205381, an organic resin is used as a refractory material containing carbon to improve the packing density and durability, but a hot flow effect cannot be obtained.

Further, in JP-A-56-26777 and JP-A-57-205381, it is an absolute condition that water is added to secure adhesiveness, shape retention and workability. It had serious drawbacks such as heat spalling of the base material. Further, when these amorphous refractories are used hot, the temperature rises due to the residual heat of the furnace, and since the change in temperature is large and the amount used is not constant,
It is normal for the non-thermal effects of a material to change constantly. For this reason, the pitch and phenolic resins that have been conventionally used cannot provide a carbon bond structure with high hot strength.

The cause of this is deeply related to the melting point and solidification temperature of the pitch and the phenol resin. As for the structure after carbonization by heat, the pitch has the flow structure shown in FIG. 2, and the phenol resin has the glass structure shown in FIG. Due to the flow structure, the refractory has excellent spalling resistance, but has low strength and poor wear resistance and corrosion resistance. Also, in the case of a glass structure, although it has high strength and excellent wear resistance,
Poor spalling resistance. The flow structure and the glass structure produced by carbonizing the pitch or the phenol resin have the respective advantages and disadvantages.

[0007]

The amorphous refractory material for hot repair of the present invention has a melting point temperature difference of 100 ° C. or less and a solidification temperature difference of 300 ° C. or less with respect to 100 wt% of refractory aggregate. Pitch and novolac type phenolic resin, the weight ratio of both is 0.3 to 12.5, and the total amount is 5 to 25w.
It is an amorphous refractory characterized by adding t%. Further, the amorphous refractory is characterized by further granulating the irregular refractory.

The pitch used in the present invention has, for example, a fixed carbon amount of about 40 to 60 wt%, a melting point of 120 ° C. or less, and a solidification temperature of 450 to 550 ° C. As a pitch used as a binder for refractory materials. Has a particularly low melting point. The novolak type phenolic resin has a number average molecular weight of, for example, 200.
~ 300, melting point 70 ° C or less, solidification temperature 250 ~ 40
It is 0 ° C., and a phenol resin usually used as a binder for refractory materials has a low melting point and a high solidification temperature.

According to the present invention, the pitch of these characteristics and the novolac type phenolic resin are blended in a weight ratio (P / N ratio) of 0.3 to 12.5 to form an amorphous fire resistant material for hot repair. In the object, a carbonized structure having a mosaic structure as shown in FIG. 1 is easily formed. Due to the carbonized structure of the mosaic structure, the amorphous refractory becomes a material having excellent spalling resistance, hot strength, corrosion resistance and wear resistance. Further, the total amount of the pitch and the novolac-type phenol resin is 5 to 25 wt% with respect to the refractory aggregate, and the effect of filling property, strength, corrosion resistance, etc. is exhibited without separation of the aggregate when heated. Further, by granulating this irregular shaped refractory, there is an effect of adjusting the melting-solidifying time during heating.
As a result, it is possible to obtain a highly filled construction product that is expected to have high durability and is excellent in filling uniformity.

Conventionally, when pitch or phenolic resin is used by adding it to the refractory aggregate, the pitch or phenol resin is selected according to the characteristics of these binders and the pitch or phenol resin is used according to the construction conditions such as furnace heat. The type of phenolic resin and the amount added were determined. In addition, the combination of pitch and phenol resin was mainly used for the purpose of adjusting the curing time by utilizing the fast curing property of phenol resin. As in the present invention, positively forming a mosaic structure to improve the material properties is a liquefaction of the pitch and the phenol resin due to the unstable construction conditions such as residual heat of the furnace in the prior art. It was not carried out because it was difficult to adjust the compatibility in the state.

[0011]

[Function] By using pitch and phenol resin together, the generation process and generation mechanism of a mosaic structure having useful properties as a refractory material have not been clarified at present, but the following generation process is adopted. Thought to be a thing. The novolac type phenol resin used in the present invention starts softening and melting at about 50 ° C and solidifies at about 400 ° C. The pitch starts softening and melting at about 80 ° C and solidifies at about 500 ° C. When the pitch and the novolac type phenol resin coexist in the above ratio, both are first liquefied by being heated. After that, the novolac-type phenol resin begins to solidify, but the solidified portion of the novolac-type phenol resin is scattered in the entire liquid phase part of the pitch in the liquefied state. Further, the pitch starts to solidify as the temperature rises. At this time, the novolac-type phenolic resin that started to cure first becomes the core, which hinders the formation of the flow structure of the pitch, and the chain-like ring of the pitch undergoes a condensation reaction around the core to form a three-dimensional mosaic structure. To form.

Since the carbon bond structure of the flow structure shows a flow structure, latent microcracks along the flow structure are likely to occur in the structure of the refractory material, and the fracture toughness is lowered, resulting in low hot strength. Will be the organization of. The glass-like structure has a high-strength structure, which is a carbon bond peculiar to a phenol resin, but is an amorphous uniform structure, and therefore has a structure with low crack propagation resistance and low spalling resistance.

On the other hand, the mosaic structure obtained by the present invention is an aggregate of carbon grains, and has improved spalling resistance and improved fracture toughness and crack propagation resistance of carbon bond. In addition, it has a high hot strength, excellent corrosion resistance, and excellent wear resistance, and is a useful structure as an amorphous refractory. What is important in the generation of this mosaic structure is to sufficiently mix the pitch and the phenol resin during the liquefaction. For that purpose, the liquefaction time (the liquefaction temperature range) of the pitch and the phenol resin is similar. In addition, it is important that the liquefaction time of both is long and the viscosity of each is low at the time of liquefaction in order to enhance the compatibility.

The pitch and phenolic resin used for conventional amorphous refractories are not intended to positively form such a mosaic structure. Since pitch is used as a carbon source, it has a large fixed carbon amount, and has a high melting point and high viscosity. Also, like the pitch, the phenolic resin serves as a carbon source, and also aims to reduce the phenomenon of softening to melting when heated (to provide shape retention) or shorten the repair time. It was general to add hexamethylenetetramine as a resin or a curing agent, or to use a resol type phenol resin having a short liquefaction time. Therefore, these conventional and commonly used pitches or phenolic resins cannot be used to form a mosaic structure. On the other hand, from the viewpoint of compatibility, the pitch and the novolac type phenolic resin used in the present invention preferably have a low melting point, and the lower limit of the melting point is not particularly limited.

In the present invention, the amount of pitch and phenolic resin used is 100 wt% of the refractory aggregate, and the weight ratio (P / N ratio) is 0.3 to 12.5, and the total amount is 5. ˜25 wt%. In this case, the total amount is 5 wt
If it is less than%, the amount of fixed carbon in the refractory becomes too small,
Inferior in corrosion resistance. If it exceeds 25 wt%, the flow characteristics of the refractory material become large, the separation phenomenon of the refractory aggregate becomes remarkable, and the uniformity of the structure as the amorphous refractory material deteriorates. When the ratio of the pitch and the phenol resin (P / N ratio) exceeds 12.5, the pitch amount increases and the flow structure becomes visible. If it is less than 0.3, the amount of the phenol resin is too much, which tends to have a glass structure, and further, the fluidity and the workability are deteriorated due to the shortening of the liquefaction time and the filling property of the construction product is poor.

The type of refractory aggregate used in the present invention is not particularly limited, and for example, magnesia, dolomite, lime, spinel, chrome ore, alumina, silica, alumina-silica, zircon, zirconia, silicon carbide, or The main material is one kind or two or more kinds selected from brick scraps using these as aggregates. If necessary, one or more selected from humectants, dispersants, antioxidants, carbon, limestone, metal powder, organic fibers, metallic fibers and inorganic fibers may be added.

The material obtained by the present invention is effective as a repair material when used as it is, but may be further granulated. Granulation slows the heat transfer into the granules, the liquid state of the pitch and the phenol resin lasts longer, the compatibility of the pitch and the phenol resin becomes more complete, and the generation of the mosaic structure is promoted. It is effective in improving durability by improving physical properties. There is also an effect that the solidification time can be adjusted.

As a method of granulating, for example, an appropriate amount of a non-aqueous binder is added to the entire mixture, the mixture is pressure-molded, and then granulated by pulverization. Further, an appropriate amount of a non-aqueous binder may be added to the entire composition and granulated by a rolling method or the like. As the non-aqueous binder used for this granulation, for example, pitch, phenol resin, furan resin, epoxy resin, paraffin, etc. can be used.

[0019]

EXAMPLES Examples of the present invention and comparative examples are shown below.
Table 1 shows quality values of the pitch and the phenol resin used in each example. Table 2 shows the composition and test results of each example.

[0020]

[Table 1]

* Among the phenolic resins, was used in the examples of the present invention. And were used in Comparative Examples. * Among the pitches, and is used in the examples of the present invention.
And were used in Comparative Examples.

[Physical property measurement method] Fluidity: A material of 800 g was hit with an air rammer of 7 kg / cm ² 50 times to prepare a sample of 70 mouths. This sample was put into an electric furnace at 700 ° C., and softened to melted by being heated, and the extent of spread was classified into three stages of large, medium, and small. 125φ x 750 with the bottom closed and the top open
A mm metal pipe is set in the furnace, and the metal pipe is heated to 800 to 900 ° C. Then, the total amount is 20
1 kg of material is sequentially charged into the pipe from the top, 1 kg at a time. After the material was cured, a sample was cut out and the following filling property, porous layer formation ratio, spalling resistance and corrosion resistance were measured. Fillability: The apparent porosities of the middle part and the upper part of the material cylindrically formed as described above were measured. The smaller the numerical value is, the better the filling property is, and the smaller the numerical difference between the intermediate part and the upper part is, the more excellent the filling uniformity of the construction product is. Proportion of formation of upper porous layer: When the pitch and phenolic resin were melted by heat, the refractory aggregates were settled. The larger the value is, the larger the degree of sedimentation of the refractory aggregate is, and the larger the generation ratio of the porous layer of the construction body is.

Spalling resistance: 40 openings × 1 from the middle part
Cut out a 20 mm sample, 1600 to 1650 ℃
Immersed in molten steel for 3 minutes, air-cooled for 10 minutes, set as 1 cycle, repeated 5 cycles, cut the center part in the length direction, and measure the degree of cracking in the cut surface to prevent spalling resistance. It was divided into three stages, large, medium, and small, in order of superiority. Corrosion resistance: A predetermined sample was cut out from the middle portion and subjected to a rotary erosion test at 1650 ° C. using an erosion agent of steel 80: slag 20 in a weight ratio. As a comparison of erosion tests,
The erosion size of Comparative Example 10 in Table 5 corresponding to the non-aqueous baking repair material used in the converter was defined as 100, and shown as the ratio. The smaller the ratio, the higher the corrosion resistance. Hot bending strength: width 40 mm x thickness 30 mm x length 140
The sample cut into mm is placed under a non-oxidizing atmosphere at 140
After retaining for 1 hour at 0 ℃ hot, span 100mm
It was measured at.

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

[Table 6]

[0029]

[Table 7]

[0030]

As described above, the amorphous refractory material of the present invention has a melting point temperature difference with respect to the refractory aggregate as means for forming a mosaic carbon bond structure by using pitch and phenol resin in combination. Within 100 ° C and the difference in solidification temperature is 3
The pitch within 00 ° C and a novolac type phenol resin were added. Since the carbon bond structure of the mosaic structure is an aggregate of carbon grains, by improving the fracture toughness and crack propagation resistance of carbon, it exhibits excellent spalling resistance, high hot strength, corrosion resistance, and
Exhibits excellent effects in wear resistance.

[Brief description of drawings]

FIG. 1 shows a carbonized structure of a mosaic structure. Pitch and phenolic resin are mixed, and 100 at a reducing atmosphere furnace at 8 ° C / min.
It was heated to 0 ° C., held for 1 hour and carbonized. It is a drawing of a reflection micrograph (magnification 400 times).

FIG. 2 shows a carbonized structure of a flow structure. The pitch was heated to 1000 ° C. at 8 ° C./min in a reducing atmosphere furnace, held for 1 hour, and carbonized. Reflection micrograph (magnification 40
It is a drawing of 0 times.

FIG. 3 shows a carbonized structure of a glass structure. Phenol resin is heated to 1000 ° C at 8 ° C / min in a reducing atmosphere furnace, and 1
Carbonized after being held for a time. It is a drawing of a reflection micrograph (magnification 400 times).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Saburo Matsuo, No. 1 Tobahata-cho, Tobata-ku, Kitakyushu, Fukuoka Prefecture (72) Inside the Yawata Works, Nippon Steel Corporation (72) Taizo Taehiro, Niihama, Arai-machi, Takasago, Hyogo Prefecture 1-3-1 Harima Ceramics Co., Ltd. (72) Inventor Yoshinobu Kambe 1-3-1 Niihama, Arai-cho, Takasago-shi, Hyogo Prefecture 1-3-1 Harima Maseramic Co., Ltd. (72) Iyuko Hayashida 1-Shinhama, Arai-cho, Takasago-shi, Hyogo Prefecture 1- 3-1 Harima Maseramic Co., Ltd.

Claims (2)

[Claims] 1. A pitch and a novolac type phenol resin having a melting point temperature difference of 100 ° C. and a solidification temperature difference of 300 ° C. with respect to 100 wt% of a refractory aggregate, and a weight ratio of both is 0.3 to 12. .5, the total amount is 5 to 25w
An amorphous refractory characterized by the addition of t%. 2. An irregular refractory material obtained by granulating the irregular refractory material according to claim 1.