JP4922851B2 - Indefinite refractory - Google Patents

Description

  The present invention relates to an indeterminate refractory used for a kiln furnace or cover lining that receives molten metal, molten slag, etc., such as a blast furnace slag, cupola, and incinerator.

Refractories for lining such as blast furnace slags, cupolas, incinerators, etc. are susceptible to wear due to infiltration and melting of molten slag. For example, blast furnace slag has a basicity (CaO / SiO ₂ ratio) as low as about 1 and violently infiltrates the refractory. For this reason, raw materials (carbides and carbons) that impart properties that make it difficult to wet molten slag are used for refractories applied to such sites. Among these, silicon carbide (SiC) is excellent in fire resistance and volume stability and is used as a raw material for many refractories because it is mass-produced and inexpensive compared to other carbides.

Many non-oxide refractory materials that combine non-oxide refractory materials such as silicon carbide and oxide-based refractory materials such as alumina (Al ₂ O ₃ ) or spinel (MgAl ₂ O ₄ ) that have excellent fire resistance There are disclosed examples. For example, JP-B-57-38554 (Patent Document 1) includes at least one of silicon carbide, silicon nitride, iron iron nitride, carbon and pitch (5 to 50% by weight), alumina, alumina-magnesia spinel, 100 wt% of refractory raw material made by mixing 85 to 98 wt% of refractory aggregate consisting of at least one of high alumina chamotte, zirconia, zircon chamot, rholite, silica stone and fused silica, and 15 to 20 wt% of clay A molten metal ridge lined with a refractory for casting containing 0.01 to 0.3 parts by weight of a peptizer and 0.1 to 2.0 parts by weight of a flocculant having a slow solubility is disclosed.

  Japanese Patent Laid-Open No. 3-164479 (Patent Document 2) describes a silicon carbide bone having a SiC content of 70% by weight or more, a porosity of 10% or less, a filling bulk specific gravity of 1.25 or more for coarse grains, and 1.60 or more for medium grains. A composition containing silicon carbide 70 to 95% by weight, carbonaceous raw material 1 to 7% by weight, alumina fine powder 3 to 20% by weight, and silica ultrafine powder 0.5 to 5% by weight. A blast furnace pouring refractory material to which is added is disclosed. This high silicon carbide brazing material is described as preferable for slag lines.

Japanese Patent Laid-Open No. 5-339065 (Patent Document 3) describes, in terms of weight ratio, silicon carbide 5 to 25%, carbon 1 to 5%, alumina ultrafine powder 5 to 15% having a particle size of 5 μm or less, and alumina cement 0.5 to 7 % Is the main material, and the balance is MgO—Al ₂ O ₃ spinel. This spinel-silicon carbide-carbonaceous brazing material is described as preferred for metal lines.

One of the major factors affecting the durability of silicon carbide-containing refractories as described in the above literature is the oxidation of silicon carbide. Hot metal containers such as blast furnace slags and slag covers are at least partially exposed to the atmosphere and are therefore easily oxidized. When silicon carbide reacts with O ₂ gas or CO gas and oxidizes, the corrosion resistance decreases due to the reduction of silicon carbide and the generation of SiO ₂ . That is, it is known that silicon carbide is oxidized by CO gas as shown in the following formula (Non-patent Document 1).

Since this reaction proceeds continuously inside the brazing material containing silicon carbide, the silicon carbide content may be reduced to about 4/5 to 1/2 of the initial addition amount. Moreover, since SiO ₂ is generated, the slag penetration resistance and corrosion resistance of the refractory are significantly reduced compared to the initial use.

As described above, the oxidation of silicon carbide greatly affects the durability of the refractory construction body and increases the frequency of repairing the construction body. Therefore, it is extremely important to suppress the oxidation of silicon carbide from an economical viewpoint. For this reason, in Patent Document 2, by using a silicon carbide aggregate having a low porosity and a small surface area, the corrosion resistance and oxidation resistance of a silicon carbide material that has been problematic until now can be greatly improved. Are listed. Japanese Patent Application Laid-Open No. 2004-137122 (Patent Document 4) discloses 10 mass% or more of silicon carbide, 8 to 18 mass% of alumina-silicon carbide mixed fine powder [alumina fine powder / silicon carbide fine powder ratio of 0.8 to 7 (mass ratio). 42 to 62 parts by mass with a center particle size of 10 to 6 μm, 20 to 40 parts by mass with a center particle size of 5 to 2 μm, and 18 to 38 parts by mass with a center particle size of 1 to 0.5 μm And a dense structure obtained by using a refractory composition exhibiting extremely good fluidity with a low amount of water containing 0.3 to 6% by mass of amorphous silica fine powder (central particle size of 0.5 μm or less) A construction body is disclosed. It is described that when the structure becomes denser, the oxidation of silicon carbide is suppressed, so that a construction body having excellent corrosion resistance and less cracking and peeling can be obtained. However, these methods have not completely eliminated the deterioration of slag penetration resistance and corrosion resistance due to the progress of oxidation of silicon carbide.
Japanese Patent Publication No.57-38554 Japanese Patent Laid-Open No. 3-164479 JP-A-5-339065 JP 2004-137122 A "Behavior of non-oxides contained in casting materials for blast furnace dredging" Nobuaki Muroi et al., Refractory 43, 617 (1991)

  Accordingly, an object of the present invention is to provide an amorphous refractory having high corrosion resistance over a long period of time by suppressing deterioration of the refractory accompanying the progress of oxidation, which is a defect of the amorphous refractory containing silicon carbide. It is to be.

As a result of diligent research in view of the above-mentioned object, the present inventor has found that titania (TiO ₂ ) fine powder and / or chromia (Cr ₂ O) that generates stable carbide in a CO gas atmosphere on an amorphous refractory containing silicon carbide. ₃ ) The inventors have found that an amorphous refractory with little oxidative deterioration during long-term use can be obtained by containing fine powder, and the present invention has been conceived.

That is, the amorphous refractory of the present invention contains 5 to 35% by mass of silicon carbide fine powder and 3 to 20% by mass of titania fine powder as refractory fine powder in 100% by mass of the refractory composition, and alumina as a curing agent. It contains 0.5 to 8% by mass of cement .

  The amorphous refractory of the present invention containing silicon carbide fine powder and titania fine powder and / or chromia fine powder in a specific ratio is deteriorated in slag penetration resistance and corrosion resistance due to oxidation of silicon carbide even when used for a long time. Therefore, it is suitable as a lining material for various kilns and covers.

[1] Mechanism of operation In silicon carbide-containing amorphous refractories, if silicon carbide fine powder and titania fine powder and / or chromia fine powder are contained in a specific ratio, silicon carbide in the refractory is oxidized by CO gas during operation. However, since titania and / or chromia carbides are generated at the same time, the decrease in the amount of carbides can be suppressed as a whole, and a refractory with little oxidative deterioration can be obtained even when used for a long period of time. The guess about this action mechanism is explained below. However, the following guesses do not limit the present invention.

  A temperature gradient is generated inside the various furnace lining refractories in operation, with the surface temperature on the operating surface side being the highest temperature and the back surface being the lowest temperature. In the case of blast furnace lining refractories, the surface temperature is about 1500 to 1550 ° C, and the boundary temperature between the base material (also called workpiece material) and the backing material (also called back material and permanent material) is 1200 to 1300. It is about ℃. As described above, silicon carbide-containing amorphous refractories such as alumina-silicon carbide-carbonaceous and spinel-silicon carbide-carbonaceous are often used as refractories for linings such as blast furnaces, cupolas, incinerators, etc. Yes.

The inside of such a refractory containing silicon carbide and carbon is a CO gas atmosphere during operation. That is, when carbon and oxygen coexist, the oxidation of carbon starts from 400 to 800 ° C. and generates CO ₂ gas and / or CO gas. The CO / CO ₂ gas molar ratio (= Pco / Pco ₂ ) increases as the temperature increases. Above 1100 ° C., CO ₂ gas is almost negligible and can be regarded as only CO gas. On the high temperature side of the surface, a glass film is formed by SiO ₂ generated by the oxidation of silicon carbide, and this film greatly suppresses the supply of O ₂ gas from the surface to the inside of the refractory. The atmosphere will be maintained.

  Here, when the chemical equilibrium formulas of carbides and oxides in a high-temperature CO gas atmosphere are shown for three metal elements (compounds) of Si, Ti and Cr, the following formulas (i) to (iii) Become.

  The equilibrium temperature of these chemical equilibrium formulas, that is, the temperature at which the rate of reaction proceeding to the right (carbide oxidation reaction: oxide formation reaction) is the same as the rate of reaction proceeding to the left (carbonization reaction of oxide: carbide formation reaction). Can be obtained from the standard free energy data of the JANAF thermochemical table. Based on the data of the JANAF thermochemical table, the standard free energy change (ΔG) including other metal elements was calculated and shown in FIG. Predicted that carbide formation occurs in the temperature range where the standard free energy change (ΔG) is positive (higher than the equilibrium temperature) and oxide formation occurs in the negative temperature range (lower temperature range than the equilibrium temperature). it can.

  From FIG. 1, the equilibrium temperature between the oxide formation reaction and the carbide formation reaction in the CO gas atmosphere is about 1518 ° C. in the case of Si. As mentioned above, since the surface temperature of the blast furnace pit is about 1500-1550 ° C, the inside of the blast furnace refractory construction body is considered to be 1518 ° C or less over the whole, and the standard free energy change ( ΔG) is in a negative temperature range, that is, a temperature range in which an oxide formation reaction of silicon carbide proceeds. In contrast, the equilibrium temperatures of Ti and Cr are about 1288 ° C. and about 1115 ° C., respectively, which is lower than that of Si. Therefore, in refractories for blast furnaces, Ti and Cr are different from Si in that the standard free energy change (ΔG) is in the positive temperature range near the back of the base metal, and the carbide formation reaction changes from oxide to carbide. It can be predicted that the temperature is in the temperature range where the generated carbides exist stably.

  Therefore, in the amorphous refractory containing silicon carbide, if titania fine powder and / or chromia fine powder are contained, it can be predicted that the carbonization reaction of titania and / or chromia proceeds simultaneously with the oxidation reaction of silicon carbide inside the refractory in operation. . For example, when titania fine powder is contained, the reactions of the following formulas (i) and (iv) are considered to proceed.

  When the formula (i) and the formula (iv) are put together, the formula (v) is obtained.

Thus, the SiC oxide formation reaction [formula (i)] and the TiO ₂ carbide formation reaction [formula (iv)] proceed simultaneously. In other words, silicon carbide disappears due to the oxidation reaction with CO gas and precipitates carbon, but since the formation of titania carbide is also progressing, the total amount of carbide inside the refractory is hardly reduced, resulting in slag. It becomes a refractory with little deterioration of permeability and corrosion resistance.

The equilibrium temperature of other metal elements is 1558 ° C. for B, 1657 ° C. for Zr, 1800 ° C. for Al and Mg, and the oxide is stable up to a temperature higher than Si. In other words, even if oxides such as zirconia (ZrO ₂ ) and alumina (Al ₂ O ₃ ) are contained in an amorphous refractory containing silicon carbide for blast furnace fire, the inside of the refractory construction body for blast furnace fire during operation These carbide formation reactions do not occur in the temperature range. Therefore, the effect of the present invention that suppresses deterioration of the refractory due to the progress of the oxidation of silicon carbide and decreases the amount of carbide, and continues to have high corrosion resistance over a long period of time cannot be obtained.

In the present invention, titania fine powder is particularly an essential component, but similar effects can be expected even when chromia or tantalum oxide (Ta ₂ O ₅ ) is used from FIG. However, since tantalum oxide is very expensive, it is not economical.

[2] Composition of the amorphous refractory The case where the amorphous refractory of the present invention containing silicon carbide fine powder and titania fine powder is used as a cast refractory used in a blast furnace slag, cupola, incinerator or the like will be described as an example. The cast refractory is composed of a refractory composition containing a refractory aggregate, a refractory fine powder, and a hardener, and various additives such as a dispersant.

(A) Refractory composition
(1) Refractory aggregate The refractory aggregate is at least one selected from electrofused or sintered products such as alumina, spinel, mullite, bauxite, chamotte, zirconia, and silicon carbide. Use two or more refractory aggregates as needed.

(2) Fire-resistant fine powder The fire-resistant fine powder used in the present invention contains silicon carbide fine powder and titania fine powder, and may further contain chromia fine powder.

The content (purity) of SiC in the silicon carbide fine powder is preferably 90% by mass or more. Components other than SiC include metallic iron or iron oxide. Since metallic iron or iron oxide promotes oxidation of silicon carbide and promotes deterioration, it is preferable that it be as small as possible. From the viewpoint of high corrosion resistance, the SiC content in the silicon carbide fine powder is preferably 94% by mass or more, and the content of metallic iron or iron oxide is more preferably 1% by mass or less in terms of Fe ₂ O ₃ . The particle size of the silicon carbide fine powder is preferably about 0.3 mm or less.

The amount of silicon carbide fine powder is preferably 5 to 35% by mass with respect to 100% by mass of the refractory composition. If it is 5 mass% or more, not only the slag permeation preventing effect and corrosion resistance are obtained by the action of the silicon carbide fine powder itself, but also acts as a carbon source for the carbide formation reaction of the titania fine powder contained together. SiO ₂ produced by oxidation of silicon carbide fine powder forms a glass film on the surface of the refractory and suppresses the intrusion of O ₂ gas into the refractory. As a result, CO gas and CO ₂ gas molar ratio of the coexisting therein refractory (CO / CO ₂ gas molar ratio) increased significantly, carbonization of titania fine CO gas atmosphere is formed is to proceed. When the content of silicon carbide fine powder is less than 5% by mass and the glass film is not sufficiently formed, O ₂ gas continuously penetrates into the refractory, and the CO / CO ₂ gas molar ratio decreases, The carbonization reaction of the titania fine powder does not proceed, or the carbide once generated returns to the oxide again. On the other hand, when the content of silicon carbide fine powder is more than 35% by mass, the amount of added water is increased and the sinterability is insufficient, and the structure becomes brittle, so that the corrosion resistance is lowered.

The content of the titania fine powder is 3 to 20% by mass, preferably 4 to 15% by mass. Further, when the chromia fine powder is contained, the total amount of the titania fine powder and the chromia fine powder is preferably within the above range. Certain oxides, such as titania and chromia, produce stable carbides in a CO gas atmosphere in which the oxidation of silicon carbide within the construction of the amorphous refractory proceeds. The present invention actively utilizes this characteristic.

By containing titania fine powder and / or chromia fine powder, even if oxidation of silicon carbide fine powder proceeds, instead of titania and / or chromia carbide, the total amount of carbide is constant, slag penetration resistance and corrosion resistance The effect which prevents degradation, etc. is acquired. If the total amount is less than 3% by mass, this effect cannot be obtained. Moreover, even if it uses more than 20 mass%, only the unreacted substance (uncarbide) remains, and the effect beyond it is not acquired.

  The same effect can be obtained by using a metal such as Ti and / or Cr instead of an oxide such as titania or chromia, but an oxide is preferred from the viewpoint of availability and economy. Furthermore, titania is most preferable when considering environmental problems such as disposal and recycling of refractories after use.

The titania fine powder and chromia fine powder to be used preferably have a purity of 90% by mass or more. From the viewpoint of high corrosion resistance, the purity is more preferably 94% by mass or more, and the content of metallic iron or iron oxide is more preferably 1% by mass or less in terms of Fe ₂ O ₃ . In particular, metallic iron or iron oxide promotes oxidation of coexisting silicon carbide and promotes deterioration, so it is preferable that it be as small as possible. Further, the particle size of the titania fine powder and the chromia fine powder may be 0.3 mm or more, but a fine powder of about 0.3 mm or less is more preferable because it is more effective.

  As other refractory fine powders, electrofused or sintered products such as alumina, spinel, mullite, magnesia, zirconia, and silica fume, clay, zircon, silicon nitride, carbons, and the like can be used as necessary. Moreover, graphite powder, carbon black, pitches, etc. can be used as carbon fine powder.

(3) Alumina cement is used as the hardener for the refractory material poured into the hardener. The alumina cement to be used is not particularly limited as long as it is used for an ordinary amorphous refractory. Among them, calcium aluminate is a main component, CaO is 10 to 30% by mass as chemical components, and Al ₂ O ₃ is 70 to 70%. 90% by mass is suitable. The blending amount of the alumina cement is preferably 0.5 to 8% by mass and more preferably 1 to 6% by mass with respect to 100% by mass of the refractory composition. When the amount of alumina cement is less than 0.5% by mass, a refractory with sufficient strength cannot be obtained, and when it exceeds 8% by mass, the corrosion resistance of the refractory is inferior. However, in the cast refractory used for wet spraying construction, alumina cement may not be used, and it may be cured only with the quick setting agent.

(B) Additive
(1) Dispersant Addition of a dispersant is effective for cast refractories. The dispersant acts on the refractory fine powder to bring about a water reducing effect. Dispersants include condensed phosphates such as sodium hexametaphosphate and sodium tripolyphosphate, β-naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate, amino sulfonic acid and its salt, lignin sulfonic acid and its salt Polyacrylic acid and its salt, polycarboxylic acid and its salt, oxycarboxylic acid and its salt and the like are preferable, and these can be used alone or in combination. The addition amount of the dispersant is preferably 0.01 to 1% by mass (outside percent) with the refractory composition being 100% by mass. If the addition amount of the dispersant is 0.01 to 1% by mass (external ratio), a sufficient dispersion effect for the fireproof fine powder can be obtained.

(2) Other additives Other additives include boric acid, phosphoric acid, oxycarboxylic acid, curing time adjusters such as alkali carbonates, inorganic or metal fibers, metal aluminum, oxycarboxylate, organic fibers Examples include explosion prevention materials. Further, a fine powdery sintering aid such as metal silicon and an antioxidant such as boron carbide can be used.

[3] Experimental Example The experimental results confirming whether the chemical reaction shown above actually occurs are shown below. An amorphous refractory having the composition shown in Table 1 was kneaded, poured into a mold, molded, unframed after curing, and dried (110 ° C. × 24 hr) to obtain a test piece. This test specimen was embedded in coke powder to be placed under a CO atmosphere (however, the CO gas partial pressure was approximately 0.33 atm because N ₂ gas was actually present). The sample was calcined for 5 hours at a temperature near the boundary temperature with the material, and then analyzed by a powder X-ray diffraction method. The results are shown in Table 1. However, since silicon carbide is composed of polymorphic (4H, 6H, etc.) crystals and the diffraction intensity varies somewhat, the diffraction intensity is VS>S>M>W> nd [VS: very strong, S: Strong, M: middle, W: weak, nd: not detected].

注^※１：粒径5〜0mmとは、5mmアンダー粒径のことである。
注^※２：微粉のメジアン径は、株式会社セイシン企業製レーザー回折・散乱式粒度分布測定装置を用いて測定した体積基準の値である。

^{* 1} : The particle size of 5 to 0 mm is the 5 mm under particle size.
^{* 2} : The median diameter of the fine powder is a volume-based value measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Seishin Corporation.

In Experimental Example 2, in which titania fine powder was added to Experimental Example 1, the formation of titanium carbonitride [Ti (C, N)] was observed, and in Example 2, silicon carbide fine powder was removed and carbon black was added. Similarly, the formation of titanium carbonitride [Ti (C, N)] was recognized in No. 4, so that titania reacted with silicon carbide, carbon (carbon black) or carbon released during oxidation of silicon carbide to form carbides. Was found to produce Since the formation of chromium carbide (Cr ₃ C ₂ ) was also observed in Experimental Example 3 to which fine chromia powder was added, chromia was released during oxidation of silicon carbide, carbon (carbon black) or silicon carbide as well as titania. It is thought to react with the generated carbon to produce carbide.

In addition, silicon carbide produces silicon dioxide (SiO ₂ ) by oxidation, and this reacts with the alumina cement clinker mineral such as CaAl ₂ O ₄ to produce anorthite (CaAl ₂ Si ₂ O ₈ ). It was confirmed. This oxidation reaction of silicon carbide occurs regardless of the presence or absence of titania or chromia (Experimental Examples 1 to 3). On the other hand, unlike titania fine powder and chromia fine powder, aluminum carbide (Al ₄ C ₃ ) was not generated in the case of Experimental Example 1 to which alumina (Al ₂ O ₃ ) fine powder was added, and carbide formation reaction by alumina did not occur. I understood that. The produced titania carbide was detected as titanium carbonitride [Ti (C, N)] in which N ₂ gas was dissolved. Titanium carbonitride is produced from a temperature lower than 1288 ° C, and the C / N ratio varies depending on the firing conditions such as temperature. In addition, the composition of the generated chromium carbide varies depending on the firing temperature. For example, it becomes Cr ₃ C _{2 at} 1300 ° C. and Cr ₇ C _{3 at} 1500 ° C.

Experimental Example 4 is an example in which only silicon black is contained without containing silicon carbide fine powder. However, in an actual furnace that is strongly affected by the atmosphere, a glass film caused by fine silicon carbide powder is formed on the surface of the refractory. If it is not formed, the oxidization loss of carbon and the oxidation of carbide are easily caused by the continuous intrusion of O ₂ gas into the refractory construction body. Therefore, a configuration not containing silicon carbide fine powder is not preferable.

Further, in Experimental Example 5 containing only titania fine powder and containing neither silicon carbide fine powder nor carbon black, titanium carbonitride [Ti (C, N)] was not generated as described above, but aluminum titanate (TiAl ₂ O _4). ) Produced.

  From the above experimental examples, in a silicon carbide-containing amorphous refractory, if titania fine powder and / or chromia fine powder are contained, the carbonization reaction of titania and / or chromia occurs simultaneously with the oxidation reaction of silicon carbide inside the refractory during operation. It was confirmed that it would progress. In other words, as described above, silicon carbide disappears due to oxidation reaction with CO gas and precipitates carbon, but on the other hand, since the formation of titania carbide is also progressing, the total amount of carbide inside the refractory hardly decreases. As a result, it becomes a refractory with little deterioration of slag permeability and corrosion resistance.

As shown in the examples below, amorphous refractories that do not contain titania fine powder or chromia fine powder are inferior in corrosion resistance to those containing these, so in the oxide generation reaction of SiC [formula (i)] It is presumed that C (carbon) produced simultaneously with SiO ₂ is less effective in preventing slag penetration and improving corrosion resistance than the produced carbide (titanium carbide or chromium carbide). The reason is considered to be due to the difference in crystallinity between C and carbide produced. That is, C precipitated by the reaction of the formula (i) cannot be confirmed by analysis by the powder X-ray diffraction method, so it is considered that it is amorphous or low in crystallinity, while the generated carbide is determined by the powder X-ray diffraction method. The crystallinity seems to be high because it can be clearly confirmed by analysis. This difference in crystallinity is considered to be a cause of the difference in slag penetration resistance and corrosion resistance.

[4] Examples The present invention will be described in more detail below with reference to cast refractories, but the present invention is not limited to these examples.

Examples 1 to 12, Reference Examples 1 and 2, Comparative Examples 1 to 7
(1) Method for preparing cast refractory In addition to silicon carbide fine powder (particle size 0.074 mm or less), titania fine powder (median diameter 0.4 μm) or chromia fine powder (median diameter 1 μm), refractory aggregate, alumina fine powder (particle size 0.074 mm or less and / or median diameter 0.7 μm), carbon black, alumina cement, and a dispersant were blended according to the formulation shown in Table 2 to prepare a cast refractory. Here, the median diameter of the fine powder is a volume-based value measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Seishin Corporation. Each cast refractory was kneaded with the amount of water shown in Table 2-1 to Table 2-3, cast into a predetermined form, cured at room temperature for 24 hours, de-framed and dried at 110 ° C. for 24 hours. . About the obtained molded object, the erosion test was done by the following method.

(2) Erosion Test Method After each test piece was set on the furnace wall of the induction furnace, pig iron was melted in the furnace (in the atmosphere), and the erosion test was conducted with floating blast furnace slag on it. The erosion test temperature and time were 1550 ± 40 ° C x 12 hours. The dimensional difference of each test piece before and after the erosion test was measured and converted into the amount of erosion per hour. The results are shown in Tables 2-1 to 2-3. In addition, all the induction furnace erosion test results shown in Table 2 are results when the test pieces after drying at 110 ° C. × 24 hours are used as they are.

注^※１：粒径5〜0mmとは、5mmアンダー粒径のことである。
注^※２：微粉のメジアン径は、株式会社セイシン企業製レーザー回折・散乱式粒度分布測定装置を用いて測定した体積基準の値である。

^{* 1} : The particle size of 5 to 0 mm is the 5 mm under particle size.
^{* 2} : The median diameter of the fine powder is a volume-based value measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Seishin Corporation.

注^※１：粒径5〜0mmとは、5mmアンダー粒径のことである。
注^※２：微粉のメジアン径は、株式会社セイシン企業製レーザー回折・散乱式粒度分布測定装置を用いて測定した体積基準の値である。

^{* 1} : The particle size of 5 to 0 mm is the 5 mm under particle size.
^{* 2} : The median diameter of the fine powder is a volume-based value measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Seishin Corporation.

注^※１：粒径5〜0mmとは、5mmアンダー粒径のことである。
注^※２：微粉のメジアン径は、株式会社セイシン企業製レーザー回折・散乱式粒度分布測定装置を用いて測定した体積基準の値である。

^{* 1} : The particle size of 5 to 0 mm is the 5 mm under particle size.
^{* 2} : The median diameter of the fine powder is a volume-based value measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Seishin Corporation.

  Examples 1-11 are the examples which contain silicon carbide fine powder and titania fine powder (median diameter 0.4 micrometer) in the ratio prescribed | regulated to this invention, and all were excellent in corrosion resistance. Examples 1 to 9 are examples containing carbon black (carbon fine powder), and Examples 10 and 11 are examples not containing carbon black. It can be seen that the presence or absence of carbon black has little effect on corrosion resistance.

Reference Examples 1 and 2 are examples containing silicon carbide fine powder and chromia fines (median diameter 1 [mu] m), both the corrosion resistance was excellent. Example 12 for the titania fine powder used in Example 1 to 11 (median size 0.4 .mu.m), although an example in which a large titania fine particle size (particle size 0.074 mm or less), Examples 1 to 11 Corrosion resistance was excellent as well.

Comparative Examples 1 and 2 are examples in which titania fine powder was contained but silicon carbide fine powder was not contained, and the corrosion resistance was poor regardless of the presence or absence of carbon black. Comparative Example 3 was an example in which the content of silicon carbide fine powder was as low as 3% by mass, and the corrosion resistance was inferior. In either case, since the glass film is not sufficiently formed on the surface of the refractory, carbon black is easily oxidized and lost under the influence of the atmospheric atmosphere (O ₂ ), and the carbide is easily oxidized. For this reason, even if carbon black is contained, titania carbide is hardly generated. As a result, the slag is likely to penetrate and the corrosion resistance seems to have decreased.

  Comparative Example 4 is an example containing only silicon carbide fine powder and no titania fine powder or chromia fine powder. Comparative Example 5 is an example in which the content of fine titania powder is as small as 2% by mass. All of these were inferior in corrosion resistance compared to the Examples.

  Comparative Example 6 is an example in which the content of silicon carbide fine powder was further increased from Comparative Example 4, but since it did not contain titania fine powder or chromia fine powder at all, the corrosion resistance was inferior like Comparative Example 4.

  Although the comparative example 7 is an example which contains as much as 36 mass% of silicon carbide fine powder, the corrosion resistance was inferior in spite of containing the titania fine powder. This is presumably because the increase in the amount of silicon carbide powder caused an increase in the amount of added water and a lack of sinterability, which weakened the structure.

注^※１：粒径5〜0mmとは、5mmアンダー粒径のことである。
注^※２：微粉のメジアン径は、株式会社セイシン企業製レーザー回折・散乱式粒度分布測定装置を用いて測定した体積基準の値である。
注^※３：予めコークス粉中に埋設して焼成処理（1300℃×48hr）した試験片での誘導炉侵食試験結果である。
注^※４：110℃×24hr乾燥後試験片での誘導炉侵食試験結果（表２に記載したものと同じ値）である。

^{* 1} : The particle size of 5 to 0 mm is the 5 mm under particle size.
^{* 2} : The median diameter of the fine powder is a volume-based value measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Seishin Corporation.
^{* 3} : Induction furnace erosion test results with test pieces embedded in coke powder and fired (1300 ° C x 48 hr).
^{* 4} : Induction furnace erosion test result (same value as described in Table 2) on a test piece after drying at 110 ° C for 24 hours.

In Table 3, the test pieces prepared in Example 3, Example 4, Reference Example 1 , Comparative Example 4 and Comparative Example 5 were pre-embedded in coke powder and fired at 1300 ° C. for 48 hours, under a high-temperature CO gas atmosphere The results of evaluating corrosion resistance after prolonged exposure to are shown. The erosion rate values shown in parentheses in Table 3 are the results of the erosion test on the test pieces after drying at 110 ° C. × 24 hours shown in Table 2-1 to Table 2-3 for comparison. Is.

Example 3, Example 4 and Reference Example 1 containing silicon carbide fine powder and titania fine powder or chromia fine powder maintained good corrosion resistance even after being exposed to a high-temperature CO gas atmosphere for a long time.

  On the other hand, Comparative Example 4 containing only silicon carbide fine powder and containing no titania fine powder or chromia fine powder or Comparative Example 5 having a small content of titania fine powder of 2% by mass is long in a high-temperature CO gas atmosphere. The deterioration of corrosion resistance after exposure to time was great.

  Although the cast refractory has been described as an example, the amorphous refractory of the present invention can be applied to any aspect such as a stamp material and a spray material. However, the particle size configuration, the type of the curing material, and the like need to be adjusted according to the mode by applying a known technique.

It is a graph which shows the temperature dependence of the standard free energy change in reaction in CO gas atmosphere of various metals.

Claims (1)

100 wt% of the refractory composition contains 5 to 35 wt% of silicon carbide fine powder having a particle size of 0.3 mm or less and 3 to 20 wt% of titania fine powder having a particle size of 0.3 mm or less as a refractory fine powder. An amorphous refractory containing 0.5-8% by mass of alumina cement.

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