JP2002040014A - Evaluation method of abrasion resistance, corrosion resistance and oxidation resistance of carbon-including refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaluation method of corrosion resistance capable of preventing oxidation of carbon during the heating or temperature-rising time of a carbon-including refractory. SOLUTION: This evaluation method of abrasion resistance of the carbon- including refractory is characterized by heating the refractory 1 indirectly through a protection plate 2 placed on the carbon-including refractory, and, after continuing the heating until the protection plate 2 disappears or after removing the protection plate 2, blowing an abrasion medium into a burning flame, spraying the medium onto the protection plate 2 surface to thereby abrade the refractory, and measuring the remaining thickness and/or the attrition area of the refractory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for evaluating the wear resistance, corrosion resistance and oxidation resistance of a carbon-containing refractory.

[0002]

2. Description of the Related Art Carbon-containing refractories are widely used in converters, lining of mixed iron wheels, molten steel pots and slag lines of hot metal pots, and contribute to prolonging the life of kilns. This material exhibits excellent durability in combination with the effects of slag infiltration resistance and spalling resistance by carbon, and further higher durability is desired for the purpose of cost reduction. To date, typical methods for evaluating durability in a laboratory include a high-frequency induction furnace lining method and a rotary erosion method. In each case, the slag and the steel are melted at a high temperature, the melt is brought into contact with the refractory for a certain period of time, and the wear resistance of the refractory is compared to evaluate the durability. For example, JP-A-06-185
In Japanese Patent No. 20, the refractory is lined with a high-frequency induction furnace, steel and slag are added, and the durability is evaluated. Japanese Patent Application Laid-Open No. 03-291550 discloses a method in which a furnace is vibrated while steel is sealed, wear is caused on an evaluation refractory, and then the durability of the refractory is evaluated based on the amount of wear. Have been.

[0003] The high frequency induction furnace lining method can perform a comparative test on many samples at one time, and can control the atmosphere and can often reproduce the melting loss close to that of an actual furnace. In addition, since the experimental operation is not easy, the degree of penetration is inferior to the rotary erosion method. The rotary erosion method is a test in which a refractory is lined inside an iron drum, and slag and iron are dissolved inside the drum and reacted with the refractory. The temperature of the surface of the refractory is set to a predetermined test temperature. This test is widely used because the sample shape is relatively small, the furnace is easy to dismantle and dismantle, and the equipment is simple. However, the high-frequency induction furnace lining method or the rotary erosion method cannot apply a strong force to the refractory, and cannot sufficiently reproduce conditions such as a converter and RH with strong stirring power and flow. When evaluating the durability under conditions of strong stirring power and flow such as converter and RH,
A thermal spray erosion test for eroding a refractory by blowing a powdery slag into an oxygen-propane combustion flame and dissolving the slag and spraying the slag on the surface of the refractory is often performed (Refractory Handbook '99 edited by Japan Refractory Technology Association). , P.
7). In this case, since the sample to be evaluated is set in the air, it is inevitable that the atmosphere is involved with the flame.

[0004]

In the above thermal spray erosion test, when a carbon-containing refractory is targeted, a decarburized layer is formed by oxidation of carbon, particularly in a process of raising the temperature to a predetermined test temperature, It became clear that the decarburized layer was lost in the early slag. Furthermore, the ratio of the decarburized layer formed during the temperature increase to the final wear amount was large, and it was found that it was extremely difficult to perform a highly accurate evaluation of the carbon-containing refractory.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for accurately evaluating abrasion resistance, corrosion resistance and oxidation resistance of a carbon-containing refractory which prevents oxidation of carbon during heating and heating. It is in. In view of the above, the present invention introduces a protective plate between a heating source and a refractory in order to solve the problem of the adverse effect of oxidation of carbon during heating on the relative evaluation of the refractory. Accordingly, the present invention provides a method for evaluating the corrosion resistance of a carbon-containing refractory, in which the carbon-containing refractory is cut off from the air and the oxidation loss of carbon due to a flame or air during the temperature rise is suppressed.

The features of the present invention are as follows: (1) After heating the refractory indirectly to the carbon-containing refractory via the protective plate and continuing heating until the protective plate disappears, or After removing the refractory, a wear medium is blown into the combustion flame, and the refractory is worn by spraying on the refractory surface, and the residual thickness and / or worn area of the refractory is measured. Evaluation method for wear resistance. (2) The method for evaluating the wear resistance of a carbon-containing refractory according to the above (1), wherein the particle size of the wear medium is 1 to 10 mm. (3) After heating the refractory indirectly to the carbon-containing refractory via the protective plate and continuing heating until the protective plate disappears or after removing the protective plate, the slag raw material powder is burned into the combustion flame. A method for evaluating the corrosion resistance of a carbon-containing refractory, wherein the refractory is eroded by blowing a body and spraying the slag on the surface of the refractory while dissolving the slag, and measuring a residual thickness and / or a worn area of the refractory. (4) The refractory produced indirectly after heating the carbon-containing refractory for a predetermined time after heating the refractory indirectly via the protective plate and continuing heating until the protective plate disappears or after removing the protective plate. A method for evaluating the oxidation resistance of a carbon-containing refractory, comprising measuring a thickness of a decarburized layer and / or an area of a decarburized portion of the refractory. (5) The wear resistance and corrosion resistance of the carbon-containing refractory according to any one of the above (1) to (4), wherein the surface temperature of the refractory and / or the protective plate is continuously measured. Or a method for evaluating oxidation resistance. Here, the protection plate is defined as a plate that exists between a heat source such as a flame and the refractory and plays a role of blocking the action of the flame directly on the refractory surface and the action of the atmosphere entrained with the flame. . The wear medium is defined as a medium that plays a role of abrading the refractory by spraying the refractory to be evaluated.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The material of the protection plate for preventing oxidation used in the present invention may be one selected from iron, aluminum, copper and the like or a combination thereof. The chemical components of iron, aluminum, and copper are not particularly limited, and alloys may be used. If a material having a high thermal conductivity is used for the protective plate, it is considered that the surface of the brick has almost reached a predetermined temperature. In order to sufficiently exert the effects of the present invention, in consideration of heat resistance, the melting point is preferably close to the test temperature, and the melting point is preferably ± 200 ° C. or lower. If the melting point is lower than the test temperature of -200 ° C, the time for which the surface of the brick is in contact with the flame or air becomes longer, and a decarburized layer is formed on the surface. When the melting point is the test temperature + 200 ° C,
It takes time to remove the protection plate, or once the protection plate is heated until it melts, then it takes a long time to reduce the temperature to the specified test temperature, and the surface of the brick comes in contact with flame or air. The time required for the treatment is prolonged, and a decarburized layer is formed on the surface. The refractories targeted by the present invention are C,
Al ₂ O ₃ —C, Al ₂ O ₃ —SiC—C, MgO—C,
Al ₂ O ₃ -MgO-C, MgO-SiC-C, MgO-
There is no particular limitation as long as it is a refractory containing carbon, such as CaO-C.

The present invention relates to an oxidizing atmosphere, Ar, N ₂ , H
e, H _2, without limiting the heating in a non-oxidizing atmosphere such as vacuum, may be applied in any heating condition in air, refractories be included entrainment of oxygen may come into contact with oxygen is there. The gas used for heating may be any of propane-oxygen, methane-oxygen, coke oven gas, and the like.

In the above invention (1) or (3),
After heating to 1300 to 1700 ° C. depending on the test conditions and continuing heating until the protective plate disappears or after removing the protective plate, a wear medium or slag raw material powder is charged by a conventional method, and the refractory By measuring the wear state of the refractory, it is possible to accurately evaluate the wear resistance and corrosion resistance of the refractory. The components of the wear medium are not particularly limited, but it is preferable to use a material having a higher hardness than the main raw materials constituting the refractory to be evaluated. Further, it is preferable to use a material whose melting point is higher than the test temperature by 400 ° C. or more and which is stable around the test temperature. For example, zirconia blocks or coarse particles of magnesia may be used. Although the particle size of the wear medium is not particularly limited, if the particle size is less than 1 mm, a sufficient force cannot be applied to the refractory, and the amount of scattering to the surroundings increases. It is necessary to make it longer. If it exceeds 10 mm, regardless of the type of the refractory to be evaluated, the amount of abrasion increases, and it becomes difficult to make a relative comparison between the samples to be evaluated. 1 to 10
mm. Although the thickness of the protective plate is not particularly limited, it corresponds to the size of the brick to be incorporated, and it is preferable that the gap between the protective plate and the brick is as small as possible. Adhesion to the brick may be performed by any method such as applying a thin mortar or using an adhesive such as Aron ceramic.

[0010] In the invention of the above (4), after the indirect heating described above, heating is continued until the protective plate disappears, or after the protective plate is removed, heating is further performed for a predetermined time. Since the formation of a decarburized layer due to the oxidation of carbon during the heating can be prevented, the oxidation resistance of the refractory can be evaluated with high accuracy.

In the invention (5), a stable evaluation can be performed by measuring the surface temperature of the protective plate and / or the refractory with a radiation thermometer in order to quantify the evaluation conditions. . For the evaluation of abrasion resistance, corrosion resistance and oxidation resistance, the furnace was disassembled after the test, and the remaining size (in the case of oxidation resistance, the non-oxidized layer thickness) of the refractory sample was subtracted from the original size to determine the amount of wear. It is evaluated by Regarding wear resistance, since the amount of wear is large and the shape after the test is not always linear, the sample after the test is taken in as a two-dimensional image and evaluated by obtaining the area of the worn part. Is also good. When the amount of wear is large, the corrosion resistance and the oxidation resistance may be evaluated by obtaining the area of the worn part. Obviously, obtaining, comparing and evaluating the volume of the worn portion also falls within the scope of the present invention.

[0012]

The present invention will be described below with reference to examples. However, the present invention is not limited to these examples. This is an example in which the present invention was evaluated for MgO-C brick. The sample used in this test contained MgO-C bricks containing 77% of electrofused magnesia clinker of 98% purity and 20% of scale graphite of 98% purity, using phenol resin as a binder, and adding 3% of metal Al. Yes, it is widely used as refractory lining for converters. In the test, the MgO-C brick was cut into the shape shown in FIG. 1 to produce a test piece 1, and four test pieces 1 were arranged as shown in FIG. On the working surface side 10 of the test piece 1, a thickness 3
The protective plate 2 made of steel having a thickness of 2 mm was attached using Aron ceramic.

As the combustion gas, propane: oxygen 5 in a volume ratio of 5 was used. After reaching 1675 ° C., when the temperature was stabilized for 5 minutes, the burner 3 was stopped, disassembled, and the remaining size of the test piece was measured. The steel protection plate 3
When the temperature reaches 675 ° C., all of them are melted off, so that there is no problem in evaluation. The wear dimension was determined by measuring the remaining dimensions of five points (the thickness of the non-oxidized layer in the case of the decarburized layer thickness) every 10 mm, calculating the average, and further defining the average value of the four sheets.
The smaller the value, the less the decarburized fragile layer due to oxidation.

FIG. 3 relates to a graph showing a comparison of the thickness of the decarburized layer of the MgO-C brick when it is disassembled when it is stabilized at 1675 ° C. The temperature of the refractory was measured with a radiation thermometer. FIG. 4 relates to a graph showing a comparison of the wear amount of MgO-C brick after the wear test was performed after the temperature of the refractory was stabilized at the test temperature of 1675 ° C., and then the wear test was performed by using magnesia coarse particles. is there. FIG.
Conducted an erosion test with slag after the temperature of the refractory was stabilized at 1675 ° C., and performed MgO-
It is related to a graph showing a comparison of the amount of erosion of C brick. FIG. 6 is a graph showing a comparison of the thickness of the decarburized layer of the MgO-C brick after performing the oxidation test in which the combustion gas is continuously blown for a predetermined time after the temperature of the refractory is stabilized at 1675 ° C. Things.

In Examples 1 and 2, the use of the protective plate and the material of the protective plate were examined. In the first embodiment, 60 ×
A steel plate having a size of 100 mm x a thickness of 3 mm was attached to the working surface of the sample. In Example 2, an aluminum plate having a size of 60 × 100 mm × thickness of 3 mm was attached to the working surface of the sample. Comparative Example 1 is a conventional method using no protective plate. As a result, in Example 1 in which the difference between the melting point of the protective plate and the test temperature was 120 ° C., the thickness of the decarburized layer due to oxidation of the surface of the carbon-containing refractory during heating was suppressed to 2 mm.
It can be seen that oxidation loss was significantly reduced as compared with the case of FIG. Example 2 in which the difference between the melting point of the protective plate and the test temperature exceeds 900 ° C.
In this example, although the thickness of the decarburized layer could be suppressed, it can be seen that the suppression effect was at a lower level than in Example 1.
As shown by these test results, the test method according to the example of the present invention was able to significantly suppress the initial oxidation wear amount and minimize the influence of the initial wear on the total wear amount.

In the third embodiment, the refractory is heated by the method of the first embodiment, and then a magnesia coarse particle is actually sprayed to perform a wear resistance evaluation test. The component of the magnesia coarse particles was MgO: 96%, and the particle size was 1 to 5 mm. The spraying was performed at a test temperature of 1675 ° C. for 2 hours.
The spray amount of the magnesia coarse particles was 50 kg / 1 hour. The amount of wear after the test was over 10 mm, which was sufficient compared with the thickness of the decarburized layer during the temperature rise, and the wear resistance of the carbon-containing refractory could be evaluated with high accuracy. Comparative Example 2 is an evaluation result when magnesia was sprayed under the same conditions as Example 3 subsequent to Comparative Example 1. Compared with Example 3, the influence of the thickness of the decarburized layer during temperature rise was large, and high accuracy was obtained. Could not be evaluated.

In the fourth embodiment, a slag is actually introduced by the method of the first embodiment, and a corrosion resistance evaluation test is performed. The composition of the slag was CaO = 50.45, SiO ₂ =
16.85, MgO = 7, Al ₂ O ₃ = 2, MnO = 2.
5, a test was conducted in which slag was sprayed at 1675 ° C. for 2 hours with FeO = 21.2. The amount of slag sprayed was 15 kg / hour. The heating of the slag was subsequently performed with a burner under the same conditions as in Example 1.
The depth of wear was about 10 mm, which was a sufficient amount of wear even when compared with the thickness of the decarburized layer during temperature rise, and the corrosion resistance of the carbon-containing refractory could be evaluated with high accuracy. Comparative Example 3 is Comparative Example 1
This is an evaluation result when slag was introduced under the same conditions as in Example 4 following the heating of Example 4. As compared with Example 4, the amount of erosion greatly deviated, and high-precision evaluation was not possible.

In the fifth embodiment, after the temperature reaches 1675 ° C. and is stabilized by the heating method of the first embodiment, the combustion gas is
This is a case where an evaluation test of oxidation resistance that continues to be performed for a long time is performed. The thickness of the decarburized layer was 7 mm, which was a sufficient amount of wear compared to the thickness of the decarburized layer during the temperature rise, and the oxidation resistance of the carbon-containing refractory could be evaluated with high accuracy. Comparative Example 4 is Comparative Example 1
This is an evaluation result when the combustion gas was continuously blown under the same conditions as in Example 5 following the heating of Example 5. Compared with Example 5, the influence of the thickness of the decarburized layer during the temperature increase was large, and highly accurate evaluation was possible. Did not.

[0019]

According to the present invention, the protection plate prevents contact with the flame or air entrained with the flame, thereby suppressing oxidation of the surface of the refractory during heating and weakening of the surface structure. Therefore, in the test method using the protective plate according to the present invention, the wear resistance, corrosion resistance and oxidation resistance of the carbon-containing refractory can be evaluated with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the shape of a sample used in the present invention.

FIG. 2 is an explanatory view schematically showing a test method of the present invention.

FIG. 3 is a graph showing a comparison of the thickness of a decarburized layer of MgO—C brick when it is disassembled when it is stabilized at 1675 ° C.

FIG. 4 is a graph showing a comparison of wear amounts of MgO—C bricks after performing a wear test using magnesia coarse particles.

FIG. 5 shows the results of an erosion test using slag and Mg.
The graph which shows the comparison of the amount of erosion of OC brick.

FIG. 6 is a graph showing a comparison of the decarburized layer thickness of MgO-C brick after performing an oxidation test.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Test piece 2 Protective plate 3 Burner

Claims (5)

[Claims] An indirect heating of a carbon-containing refractory through a protective plate, and after the heating is continued until the protective plate disappears or after the protective plate is removed, abrasion occurs during the combustion flame. A method for evaluating the abrasion resistance of a carbon-containing refractory, which comprises measuring a residual thickness and / or a worn area of a refractory by blowing a medium and spraying the refractory on a surface of the refractory. 2. The method for evaluating the wear resistance of a carbon-containing refractory according to claim 1, wherein the wear medium has a particle size of 1 to 10 mm. 3. A method of heating a refractory indirectly through a protective plate to a carbon-containing refractory and continuing heating until the protective plate disappears or removing the protective plate, and then slagging in the combustion flame. Evaluation of the corrosion resistance of carbon-containing refractories, characterized in that the raw material powder is blown, the slag is melted, and the refractory is eroded by spraying on the refractory surface, and the residual thickness and / or the wear area of the refractory is measured. Method. 4. After the refractory is heated indirectly to the carbon-containing refractory through a protective plate, and the heating is continued until the protective plate disappears or after the protective plate is removed, the refractory is formed after heating for a predetermined time. A method for evaluating the oxidation resistance of a carbon-containing refractory, wherein the thickness of the decarburized layer and / or the area of the decarburized portion of the refractory is measured. 5. The carbon-containing refractory according to claim 1, wherein the surface temperature of the refractory and / or the protective plate is continuously measured. Evaluation method of oxidation resistance.