JP5978089B2 - Refractory manufacturing method and refractory - Google Patents

Description

  The present invention relates to a method for producing a refractory used for a jig or the like used for firing or heat treatment at a high temperature, and a refractory produced by such a method.

  Conventionally, jigs for performing firing or heat treatment at high temperatures, furnace bottoms such as steel making furnaces, incinerators, melting furnaces, etc., are usually placed in a high temperature environment exceeding 1000 ° C., and therefore the materials constituting them As refractories are used.

  The refractory usually has a heterogeneous structure in which coarse particles (aggregate) having a particle size of more than 1 mm to fine particles of 100 μm or less are mixed. In order to manufacture such a refractory, there is known a method in which baking, machining, or the like is performed after molding with a mold or molding in which water is added to a raw material and then poured into the mold.

  On the surface of the obtained refractory material, granular materials derived from raw materials having various particle sizes including aggregates appear, but dropout occurs due to cracking of the aggregate and “loosening” of the structure in the course of use. After that, when the aggregates fall off, many aggregate marks on the surface appear. If a refractory material is used for the jig, the surface of the product placed on the jig will be in a very "rough" state, and aggregates that have fallen off during heat treatment will adhere to or stick to the product. A situation arises that requires machining after heat treatment. Moreover, when a refractory is used for the bottom of various furnaces, the strength of the refractory gradually decreases due to the progress of the dropping of the aggregate, which may lead to destruction in a short period of time.

  An object of the present invention is to provide a method for producing a refractory having a smooth surface state and such a refractory in order to prevent the above-described adverse effects.

  In order to solve the above problems, the present invention is a method for producing a refractory by pouring a mixture formed after adding and mixing water to a refractory raw material particle powder into a mold, drying and firing. The amount of water added is 1.2 to 1.7 times the amount of water determined by the method for determining the amount of water described in JIS R 2553, and no vibration is applied when the mixture is poured into a mold. It is a feature.

  By producing the refractory by such a method, the surface state of the obtained refractory becomes good, and therefore, even if it is used many times, the aggregate does not fall off and the durability is improved. Can do.

  In the refractory manufacturing method of the present invention, a plurality of materials having different specific gravities may be used as the refractory raw material particle powder.

  Thus, by using a plurality of materials having different specific gravities, it is possible to manufacture a refractory having a plurality of structures having different materials in the surface layer portion and the central portion.

  Moreover, this invention relates to the refractory manufactured by said manufacturing method. As described above, the refractory of the present invention has a good surface state and excellent durability.

  In the method for producing a refractory according to the present invention, the amount of water added is 1.2 to 1.7 times the amount of water determined by the method for determining the amount of water described in JIS R 2553, and the mixture is poured into a mold. When vibration is not applied, the surface state of the refractory can be made good. For this reason, even if the refractory is used many times, the aggregate does not fall off and the durability can be improved.

It is a photograph which shows the cross-sectional state of the refractory after baking, (a) shows the refractory obtained by Example 2, (b) shows the refractory obtained by the comparative example 1. FIG. It is a photograph which shows the surface state of the refractory after baking, (a) shows the refractory obtained by Example 2, (b) shows the refractory obtained by the comparative example 1. FIG.

  Hereinafter, the manufacturing method of the refractory material by this invention is demonstrated in detail.

  The method for producing a refractory according to the present invention is by pouring a mixture formed after adding and mixing water to refractory raw material particle powder into a mold, drying and firing, and (1) refractory raw material When water is added to the particle powder, the amount of water is 1.2 to 1.7 times the amount of water determined by the method for determining the amount of water described in JIS R 2553, and (2) water When the mixture produced from the refractory raw material powder is poured into the mold, no vibration is applied.

  The refractory raw material powder used in the production of the refractory according to the method of the present invention is obtained by mixing conventionally known coarse particles (aggregate) having a particle diameter exceeding 1 mm and fine particles of 100 μm or less. Good.

  Further, the ratio of the coarse particles to the fine particles may be variously changed according to the required performance of the refractory as the final product and the properties of the coarse particles and the fine particles. The ratio of fine particles is 0.4 to 0.8.

  The amount of water added to the refractory material particle powder is 1.2 to 1.7 times the amount of water determined by the method for determining the amount of water described in JIS R2553.

  Here, according to the method for determining the amount of water described in JIS R 2553, the procedure for determining the amount of water used as a reference will be briefly described by extracting the necessary descriptions from the above and sequentially performing the following (a) to (d). Will be determined.

  (A) About 1 kg of a sample is weighed with an upper scale and placed in a bowl. However, the light castable refractory sample takes 0.5 to 1 kg depending on the type.

  (B) Add about 100 mL of water at a temperature of 20 ± 3 ° C. and knead using a kneading instrument.

  (C) The mixture is solidified in a ball shape by hand, thrown upward about 30 cm and received with one hand.

  (D) Until this state becomes a predetermined state (standard softness state; specifically, refer to JIS R 2553), the operations of (a), (b), and (c) are repeated while changing the amount of water. The amount of water used when the soft state is reached is calculated as a percentage (%) of the dry weight of the test castable refractory.

  As the mold into which the mixture obtained by adding water to the refractory raw material particle powder is poured, various forms known in the art may be used.

  Here, in the present invention, when the mixture is poured into the mold, vibration is not applied.

  Drying and firing, which are performed after pouring the mixture into the mold, are performed under conditions normally used for refractory production. For example, drying is performed by air-drying at room temperature all day and night in an air atmosphere and then heating to 600 ° C. at a temperature increase rate of 5 to 10 ° C./hour. In the case of a nitrogen atmosphere), heating is performed over 50 to 100 hours to a temperature 50 to 100 ° C. higher than the normal temperature of the refractory.

Furthermore, as a pre Symbol refractory raw material particles, when using a plurality of materials having different specific gravities, in the present invention, by the vibration is not applied when poured into the mold, after the drying and baking, the surface portion It is also possible to manufacture a refractory having a multilayer structure having different material ratios in the central portion.

(Example)
Next, some examples in accordance with the present invention and some comparative examples for comparison with the present invention were actually performed and will be described below.

  As refractory raw material powder, 30% by weight of coarse particle powder having a particle size of 1 mm or more, 40% by weight of fine powder having a particle size of 100 μm or less, and the remaining 30% by weight is a powder larger than 100 μm and less than 1 mm A commercially available alumina-based amorphous refractory was used.

(Comparative Example 1)
An amount of water corresponding to the amount of water determined by the method for determining the amount of water described in JIS R 2553 (hereinafter referred to as standard addition amount) was added to the amorphous refractory. In this amorphous refractory, the standard amount of water added was 10% by weight based on the weight of the irregular refractory.

  After adding a standard addition amount (10% by weight) of water, it was put into a mixer, mixed in this mixer, and then poured into a wooden frame (500 × 1000 mm) set on a shaking table.

  After natural drying all day and night, it was heated to 600 ° C. at a heating rate of 10 ° C./hour and dried, and then heated to 1500 ° C. over 50 hours to obtain a refractory.

  The size of the obtained refractory was 495 × 990 × 30 mm.

Example 1
A refractory similar to Comparative Example 1 except that an amount of water corresponding to 1.5 times the standard addition amount, that is, 15% by weight of water was added and was not vibrated when poured into a wooden frame. Got. The size of the obtained refractory was 495 × 990 × 30 mm as in Comparative Example 1.

(Examples 2 to 4 and Comparative Examples 2 to 7)
Although the refractory was produced in the same manner as in Comparative Example 1 and Example 1, the material was changed from alumina to silicon carbide (Comparative Example 4 and Example 4), and the amount of added water was variously changed. A plurality of types of refractories were obtained by variously changing the manufacturing conditions by adding or not adding vibration when pouring into the wooden frame.

  The conditions for producing 11 types of refractories according to Examples 1 to 4 and Comparative Examples 1 to 7 are summarized in Table 1.

  Using each of the 11 types of refractories as a firing jig, the process of firing zirconia ceramics in the atmosphere at 1400 ° C. in an electric furnace was repeated.

  Table 2 below shows the surface state and thickness of the refractory after the process.

  The results obtained with the refractories of Example 1 and Comparative Example 1 are shown in Table 2 together with the results obtained with the refractories of Examples 2-4 and Comparative Examples 2-7.

  In Table 2, ◯ indicates a case where the surface state does not change compared to before use, △ indicates a case where the aggregate has fallen, and X indicates a case where the aggregate has significantly dropped. . In addition, when the wall thickness decreased by 10% or more, it was evaluated as x.

  The refractory manufactured in Comparative Example 1 began to drop off due to cracking of the aggregate from the fifth time, and it was confirmed that the aggregate was seized on the surface of the zirconia ceramic after firing at the ninth time. It was found that the dropping of the aggregate continued and the initial thickness was reduced at the 30th time (initial 30 mm → 27 mm).

  On the other hand, it was confirmed that the refractory produced in Example 1 did not drop off the aggregate, and even in the 30th use, the surface state and thickness were not significantly different from the initial.

Table 2 is referred to for the results of other examples and comparative examples. As shown in Table 2, it is necessary to add 1.2 to 1.7 times as much water as the standard addition amount in order to obtain both a good surface condition and long-term durability of the refractory. The same results, other silicon carbide (non-oxide) ones of alumina (oxide) is obtained even.

  On the other hand, as is clear from the comparison between Example 1 and Comparative Example 6 regarding the effect of vibration during molding, when adding more water than the standard addition amount, Good results were obtained. In addition, when the amount of water smaller than the standard addition amount was added, the result was that the surface condition was bad regardless of the presence or absence of vibration.

  As shown above, when the refractory is produced by casting, it is preferable to add 1.2 to 1.7 times as much water as the standard addition amount and not perform vibration during molding. It was found that properties were obtained.

Claims (2)

A method for producing a refractory by pouring a mixture formed after adding and mixing water to a refractory raw material particle powder into a mold, drying and firing,
The amount of water added is 1.2 to 1.7 times the amount of water determined by the method for determining the amount of water described in JIS R 2553,
A method for producing a refractory material, characterized in that no vibration is applied when the mixture is poured into a mold. The method for producing a refractory according to claim 1, wherein a plurality of materials having different specific gravities are used as the refractory raw material particle powder.