TWI821649B - Refractory materials - Google Patents

Abstract

A refractory material. The refractory material is a Si-SiC refractory material with SiC particles as the main body and metal Si contained between the SiC particles. In addition, the average particle diameter of the SiC particles as the aggregate is 15 µm or less. When the cross-section of the refractory material is observed, there are more than 100 pores of 0.05 µm to 25 µm in the range of 100×100 µm.

Description

Refractory materials

This application claims priority based on Japanese Patent Application No. 2020-150060 filed on September 7, 2020. The entire contents of this application are incorporated herein by reference. This manual discloses technology related to refractory materials. In particular, a technology regarding a Si-SiC refractory material containing metallic Si between SiC particles is disclosed.

Japanese Patent Application Publication No. 2004-18332 (hereinafter referred to as Patent Document 1) discloses technology regarding Si-SiC refractory materials (silicon/silicon carbide composite materials). The refractory material in Patent Document 1 is composed of SiC particles with an average particle diameter of 0.01 to 2 µm, SiC particles with an average particle diameter of 0.1 to 10 µm, and metallic Si dispersed among the SiC particles.

SiC-SiC (Si-impregnated SiC) disperses metal Si between SiC particles as an aggregate to improve the toughness and mechanical strength of the refractory material. However, in order to make refractory materials thinner and more durable (longer life), it is necessary to further improve the characteristics. The purpose of this specification is to provide a high-strength refractory material among Si-SiC refractory materials.

The refractory material disclosed in this specification may be a Si-SiC material with SiC particles as the main body and metal Si contained between the SiC particles. In addition, the average particle diameter of the SiC particles as the aggregate is 10 μm or less, and when the cross section of the refractory material is observed, there are 100 or more pores of 0.05 μm or more and 25 μm or less in the range of 100 μm × 100 μm. In addition, this refractory material can be formed into rollers, sintering setters, and heating furnace beams.

The refractory material disclosed in this specification can be used as a component of a heating furnace or as a component within a heating furnace. Specifically, it can be used as a wall material of a heating furnace, a beam, a roller of a continuous heating furnace, a baking carrier on which an object to be burned (object to be heated) is placed, and the like.

The refractory material may be a Si-SiC refractory material with SiC particles as the main body and metal Si contained between the SiC particles. By using SiC particles with excellent heat resistance as the main body of the aggregate, the heat resistance of the refractory material can be improved. In addition, "with SiC particles as the main body of the aggregate" means that the proportion of SiC particles in the total mass of the aggregate is 50 mass % or more. That is, the aggregate constituting the refractory material may contain particles other than SiC particles. In addition, the proportion of SiC particles in the aggregate may be 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, or 95 mass% or more. In addition to SiC particles as aggregates, the refractory material may also contain, for example, B ₄ C particles and C particles.

The average particle diameter of the SiC particles may be 15 μm or less. Thereby, the structure (structural structure) of the refractory material can be densified and the mechanical strength of the refractory material can be improved. The average particle diameter of the aggregate (SiC particles) may be 10 μm or less, 7 μm or less, 5 μm or less, 3 μm or less, or 1 μm or less. In addition, the minimum particle diameter of the aggregate may be 0.05 μm or more. When manufacturing refractory materials, it can inhibit the aggregation of aggregates (particles). In addition, the maximum particle diameter of the aggregate may be 15 μm or less. It can prevent the aggregate itself from becoming defects in the structure of the refractory material and prevent the mechanical strength of the refractory material from decreasing. The particle diameter (average particle diameter, minimum particle diameter, maximum particle diameter) of SiC particles can be confirmed by observing the cross-section of the refractory material using a scanning electron microscope (SEM) or the like.

The refractory material may have more than 100 pores ranging from 0.05 μm to 25 μm in the range of 100 μm × 100 μm in the cross section of the refractory material. In other words, small-sized pores (pores of 0.05 μm to 25 μm) can be dispersedly present inside the refractory material. It can suppress the existence of large-sized pores (for example, pores larger than 50 μm) inside the refractory material and improve the mechanical strength of the refractory material. That is, the mechanical strength of the refractory material is improved by suppressing the presence of large-sized pores that may be the starting point of destruction in the interior of the refractory material. In addition, the size of the pores is the same as the particle size of the aggregate, and can be confirmed by observing the cross section of the refractory material using a scanning electron microscope or the like. Specifically, the size of the pores can be confirmed by observing a range of 100×100 μm in the cross section of the refractory material and measuring the maximum diameter of the pores appearing within this range.

In addition, the porosity (apparent porosity) of the refractory material may be 1% or less. This improves the mechanical strength of the refractory material. The porosity (apparent porosity) of refractory materials can be 0.8% or less, 0.6% or less, or 0.5% or less. In addition, the porosity of the refractory material can be measured in accordance with JIS R2205-1992.

As described above, the refractory material disclosed in this specification contains metallic Si between SiC particles. The proportion of metal Si in the refractory material may be 20 mass% or more and 60 mass% or less. If the proportion of metal Si in the refractory material is 60% by mass or less, the occurrence of internal cracks during the manufacturing process of the refractory material (mainly the firing process) can be suppressed. In addition, the proportion of metallic Si in the refractory material may be 55 mass% or less, 50 mass% or less, 45 mass% or less, 40 mass% or less, or 35 mass% or less. In addition, if the proportion of metal Si in the refractory material is 20 mass % or more, metal Si can fully fill the gaps between SiC particles (an increase in apparent porosity is suppressed). The proportion of metal Si in the refractory material may be 30 mass% or more or 40 mass% or more.

Figure 1 shows a roller 10 used in a heating furnace (not shown). The roller 10 has a cylindrical shape having a through hole 12 and is made of Si-SiC. The roller 10 is an example of a refractory material. The roller 10 is composed of SiC particles with a particle diameter of 0.4 to 15 μm and an average particle diameter of 3.0 μm as an aggregate. In addition, metallic Si exists between SiC particles. In addition, the particle size of the aggregate (SiC particles) was calculated by taking a SEM image of the cross section of the central portion of the roller 10 and measuring the shape of the aggregate existing in the range of 100 μm × 100 μm in the image. In addition, the aggregate (SiC particles) and the substance between the aggregates (metal Si) were identified by elemental analysis of the obtained SEM image using EDS.

In the range of 100 μm × 100 μm of the obtained SEM image, 722 pores ranging from 0.05 μm to 25 μm were confirmed, and no pores larger than 15 μm were confirmed. The porosity (apparent porosity) of roll 10 is 0.5%. The result of the bending strength test of the roller 10 based on JIS R1601-2008 was 448 MPa. In addition, the roller 10 is manufactured by an extrusion molding method. Since the extrusion molding method is well known, its description is omitted.

Figure 2 shows the carrier 14 used in a heating furnace (not shown). The carrier 14 has the same characteristics as the roller 10 . The carrier 14 can be manufactured by a pressing method.

Figure 3 shows the beams 16 forming a heating furnace (not shown). As shown in (A) and (B), the beam 16 is cylindrical and solid. The beam 16 may be manufactured by extrusion molding.

[Example]

Refractory materials (samples 1 to 9) with different particle diameters (average particle diameter) of aggregates (SiC particles) were produced, and the bending strength was measured. Figure 4 shows the particle size of the aggregate used in manufacturing each sample. As a specific manufacturing method of the refractory material, first, using the aggregate shown in Figure 4, an extrusion molding machine is used to manufacture a cylindrical (roller-shaped) molded body with an outer diameter of 38 mm, an inner diameter of 25 mm, and a length of 1000 mm, and the temperature is Dry in the air at 100°C for more than 24 hours. Next, after impregnating metal Si, it is fired at 1600°C in an inert gas (Ar) atmosphere to obtain a Si-SiC roll-shaped refractory material.

The bending strength of the obtained samples 1 to 9 was measured. Bending strength is measured according to JIS R1601-2008. Figure 4 shows the measurement results of bending strength. In addition, in Figure 4, along with the measurement results of bending strength, samples with a bending strength of 350MPa or more are shown as "◎", samples with a bending strength of 300MPa or more and less than 350MPa are shown as "○", and samples with a bending strength of 200MPa or more and less than 300MPa are shown as "◎" Samples with "△" and less than 200MPa are indicated as "×". "◎" and "○" are passing grades. In addition, for Samples 1 to 9, in addition to the bending strength, the particle size of the SiC particles (average particle diameter, minimum particle diameter, maximum particle diameter), the number of pores, and the number of pores in the cross-sectional observation within the range of 100 μm × 100 μm were also measured. Evaluation of rate, formability and shape retention.

The particle diameters (average particle diameter, minimum particle diameter, maximum particle diameter) of SiC particles are calculated by observing the cross section of the refractory material with an SEM and measuring all SiC particles appearing in the range of 100 μm × 100 μm. The number of pores is determined by observing the cross section of the refractory material with an SEM and visually counting the pores in the range of 100 μm × 100 μm (pores from 0.05 μm to 25 μm). In addition, porosity (apparent porosity) is measured in accordance with JIS R2205-1992. In addition, SEM observation of the cross section was performed using TM4000 manufactured by Hitachi High-Technologies Corporation. The results of the number of pores and porosity are shown in Figure 4.

Regarding the formability, the samples after extrusion molding were visually observed, and the samples with no abnormality were evaluated as "◎", the samples with deformation were confirmed as "○", and the samples with deformation and segmentation (fragments) were evaluated as "◎" "△", samples that cannot be formed due to frequent segmentation during extrusion are evaluated as "×".

For shape retention, the samples after extrusion molding were visually observed, and the samples within the design tolerance range were evaluated as "◎", the samples that deviated from the design tolerance by less than 2 mm were evaluated as "○", and the samples that deviated from the design tolerance by more than 2 mm were evaluated as "○" is "△", and a sample that cannot be substantially measured (the shape is not maintained) is evaluated as "×".

As shown in Figure 4, it was confirmed that samples (samples 1 to 6) with an average particle diameter of SiC particles of 15 μm or less and 100 or more pores of 0.05 μm or more and 25 μm or less can obtain good strength (300 MPa or more). In addition, it was confirmed that the samples (samples 1 to 5) in which the maximum particle diameter of the SiC particles was 30 μm or less had particularly good strength (350 MPa or more). In addition, it was confirmed that the samples (samples 1 to 3) in which the maximum particle diameter of the SiC particles was 15 μm or less could obtain extremely good strength (400 MPa or more). In addition, the samples showing good strength (samples 1 to 6) all had a minimum particle diameter of 0.05 μm or more and an apparent porosity of 1% or less. In addition, it was confirmed that samples 1 to 6 had better formability and shape retention than samples 7 to 9.

As mentioned above, it was confirmed that samples 1 to 3 can obtain extremely high-strength refractory materials. Comparing Samples 1 to 3 and Samples 4 to 6, Samples 1 to 3 are characterized by an apparent porosity of 0.5% or less. From this result, it was confirmed that the strength of the refractory material can be further improved by reducing the apparent porosity of the refractory material to 0.5% or less.

In the above-mentioned embodiments, examples using rollers, carriers, and beams made of refractory materials are shown. However, the refractory materials disclosed in this specification can also be used as components (products) other than those in the above-mentioned embodiments. If used in a high-temperature environment parts used. In addition, in the above-mentioned embodiment, the example of the cylindrical beam was shown, but the beam may also be in the shape of a corner prism.

Specific examples of the present invention have been described in detail above, but these are only examples and do not limit the scope of the patent claims. The technology described in the scope of the patent claims includes various modifications and changes of the specific examples illustrated above. In addition, the technical elements described in this specification or the attached drawings are technically useful individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in this specification or the accompanying drawings can achieve multiple purposes simultaneously, and achieving one of the purposes itself has technical usefulness.

10:Roller 12:Through hole 14: Vehicle for firing 16:Heating furnace beams

[Figure 1] shows an example of a refractory material (roller).

[Figure 2] shows an example of a refractory material (carrier for firing).

[Fig. 3] shows an example of the refractory material (beam for heating furnace), (A) shows the appearance of the beam for heating furnace, and (B) shows the cross section of the beam for heating furnace.

[Fig. 4] shows the results of the Example.

10:Roller

12:Through hole

Claims (7)

A refractory material, which is a Si-SiC refractory material with SiC particles as the main body of the aggregate and metal Si contained between the SiC particles, wherein the proportion of the metal Si is 20 mass % or more and 60 mass % or less, and the SiC The average particle diameter of the particles is 15 μm or less, and when the cross section is observed, the maximum particle diameter of the SiC particles is 30 μm or less in the range of 100 μm × 100 μm, and there are 100 or more particles of 0.05 μm or more and 25 μm or less in the range of 100 μm × 100 μm. pores. The refractory material according to claim 1, wherein the minimum particle diameter of the SiC particles is 0.05 μm or more in the range of 100 μm × 100 μm. The refractory material according to claim 1, wherein the proportion of the metal Si is 30 mass% or more and 47 mass% or less. The refractory material according to any one of claims 1 to 3, wherein the apparent porosity of the refractory material is less than 1%. A roller formed of the refractory material described in any one of claims 1 to 4. A carrier for firing, formed of the refractory material described in any one of claims 1 to 4. A beam for a heating furnace is formed of the refractory material described in any one of claims 1 to 4.

Images