SILICON CARBIDE-NATURED REFRACTORY BLOCK

Abstract

A silicon carbide-natured refractory block includes a fire-resistant block body, and a calcination coated layer.

The fire-resistant block body includes a silicon carbide-natured refractory having a predetermined configuration. The calcination coated layer includes silicon oxide made by heating an outer superficial portion of the fire-resistant block body to oxidize at least some of silicon carbide therein to turn the silicon carbide into the silicon oxide. The silicon oxide sinters the calcination coated layer to increase the corrosion resistance.

Claims

1-4: (canceled)

5. A process for producing a silicon carbide-natured refractory block comprising: a step of forming a castable block with a predetermined configuration cast by pouring a castable into a mold, the castable including silicon carbide in an amount of 50% by mass or more when the entire body is taken as 100% by mass, a step of calcining the castable block in the presence of oxygen and oxidizing at least a part of silicon carbide to be silicon oxide.

6. The process for producing the silicon carbide-natured refractory block according to claim 5, wherein the castable block is poured into the mold to be solidified.

7. The process for producing the silicon carbide-natured refractory block according to claim 5, wherein the castable block is poured into and pressed within the mold to be consolidated.

8. The process for producing the silicon carbide-natured refractory block according to claim 5, wherein the castable block is dried and thereafter is heated in an oxygen atmosphere.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete appreciation of the present invention and many of its advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings and detailed specification, all of which forms a part of the disclosure.

[0018] FIG. 1 is an enlarged cross-sectional diagram for illustrating partially a calcination castable refractory block according to Example of the present invention.

[0019] FIG. 2 is a silicon-element analysis diagram for showing a distribution of silicon in a cross-sectional part of the calcination castable refractory block according to Example of the present invention.

[0020] FIG. 3 is an oxygen-element analysis diagram for showing a distribution of oxygen in the same cross-sectional part as illustrated in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Having generally described the present invention, a further understanding can be obtained by reference to the specific preferred embodiments which are provided herein for the purpose of illustration only and not intended to limit the scope of the appended claims.

EXAMPLE

[0022] A preferable embodiment of the present invention will be hereinafter described. FIG. 1 illustrates a calcination castable refractory block according to Example of the present invention partially in an enlarged cross-sectional diagram. The calcination castable refractory block has a configuration with a size of 500 mm500 mm300 mm, and comprises a fire-resistant block body 1, and a calcination coated layer 2. The fire-resistant block body 1 includes a silicon carbide-natured refractory. The calcination coated layer 2 is made by heating an outer superficial portion of the fire-resistant block body 1 within an oxygen atmosphere to oxidize at least some of silicon carbide therein to turn it into silicon oxide.

[0023] The present calcination castable refractory block according to Example was obtained by the following method. First of all, a silicon carbide-natured castable, which included Al.sub.2O.sub.3, SiO.sub.2 and SiC in a chemical constituent ratio of 3% by mass, 4% by mass and 86% by mass, respectively, was prepared. The silicon carbide-natured castable was used to mold a castable refractory block having 500 mm500 mm300 mm in size, and thereafter the silicon carbide-natured castable was dried at 110 C. for 24 hours to make the castable refractory block. Then, the castable refractory block was heated at a high temperature of 1,400 C. or more in air for a few hours to form the calcination coated layer having a thickness of 1 mm approximately on the surface. Thus, the present calcination castable refractory block according to Example was completed.

[0024] The present calcination castable refractory block according to Example was cut to examine silicon-and oxygen-element distributions in a cross-sectional part of the fire-resistant block body 1 including the calcination coated layer 2. FIG. 2 shows the silicon-element distribution in a diagram, and FIG. 3 shows the oxygen-element distribution in another diagram. Note that, in both of FIGS. 2 and 3, a bold black line is drawn on a superficial boundary of the calcination coated layer 2, and another bold black line is drawn on a boundary between the calcination coated layer 2 and the block body 1. Therefore, in FIGS. 2 and 3, the calcination coated layer 2 corresponds to a section between the two bold black lines extending in the right and left, and a part of the block body 1 corresponds to a downward section under the lower bold black line. Since a section where oxygen exists becomes black, and since the part of the calcination coated layer 2 is blacker in FIG. 3 than the part of the block body 1, it is understood from FIG. 3 that oxygen was present more in the calcination coated layer 2 than in the block body 1. Moreover, since the black section of the calcination coated layer 2 in FIG. 2 indicates that silicon abounded, it is understood that the black section of the calcination coated layer 2 was silicon oxide. In addition, white sections in FIG. 2 are construed to be voids.

[0025] The present calcination castable refractory block according to Example exhibited a porosity of 10.1%, and a bulk specific gravity of 2.63%. Moreover, the present calcination castable refractory block had a compressive strength (i.e., one of the strengths) of 81 MPa, and a bending strength of 39 MPa. The present calcination castable refractory block was subjected to a corrosion test. Using a corrosive agent including blast-furnace slag (whose basicity C/S was 1.0) to which mill scale was added in an amount of 10%, the corrosion test was carried out by an induction-furnace dipping method under the following conditions: a testing temperature at from 1,500 to 1,550 C.; and a corrosion time for 6 hours. According to the corrosion test, the present calcination castable refractory block exhibited a corrosion depth of 1.7 mm at the slag-line SL section. Moreover, the present calcination castable refractory block was further subjected to a spall resistance test which was carried out by an induction-furnace dipping method under the following conditions: a testing temperature at from 1,450 to 1,550 C.; a one-cycle immersion time for 15 minutes; and an air-cooling time for 15 minutes. According to the spall resistance test, the present calcination castable refractory block endured seven rounds by a number of cycles until it fractured to fall down.

[0026] For comparison, a castable refractory block on which no calcination coated layer was formed was subjected to the same tests as set forth above. The castable refractory block with no calcination coated layer formed exhibited a porosity of 14.8%, and a bulk specific gravity of 2.42%. Moreover, the castable refractory block with no calcination coated layer had a compressive strength of 12 MPa, and a bending strength of MPa. According to the corrosion test, the castable refractory block free from the calcination coated layer 2 exhibited a corrosion depth of 5.1 mm at the slag-line SL section. According to the spall resistance test, the castable refractory block free from the calcination coated layer 2 endured seven rounds by a number of cycles until it fractured to fall down.

[0027] As described above, the silicon carbide-natured refractory block according to the present invention, especially, the present calcination castable refractory block according to Example had a compressive strength of 81 MPa, and a bending strength of 39 MPa. On the contrary, the ordinary castable refractory block had a compressive strength of 12 MPa, and a bending strength of 3 MPa. Comparing the strengths, the present calcination castable refractory block exhibited the characteristics which were enhanced extremely with respect to those of the ordinary castable refractory block. Moreover, as to the corrosion resistance, the corrosion depth was decreased greatly to 1.7 mm in the present calcination castable refractory block from 5.1 mm in the ordinary castable refractory block. In addition, the present calcination castable refractory block could maintain the spall resistance.

[0028] Thus, the silicon carbide-natured refractory block according to the present invention comprising a noble layer (i.e., the calcination coated layer) in the superficial portion exhibits increased corrosion resistance to serve as a refractory block.

[0029] Having now fully described the present invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the present invention as set forth herein including the appended claims.