WO2024038720A1 - Refractory material - Google Patents

Abstract

This refractory material is bonded to a SiC-containing aggregate by a bonding part composed of Si, Al, O, and N. According to the refractory material, the proportion of SiC in the refractory material is 60-90 mass%, and the proportions of respective elements constituting the bonding part are 0.1-1.1 mass% for Si, 4-21 mass% for Al, 4.8-19 mass% for O, and 7.2-13.1 mass% for N.

Description

refractory

This application claims priority based on Japanese Patent Application No. 2022-131208 filed on August 19, 2022. The entire contents of that application are incorporated herein by reference. This specification discloses technology related to refractories.

JP-A-10-29866 (hereinafter referred to as Patent Document 1) discloses a refractory (sialon bonded SiC brick) in which SiC particles are bonded with sialon (SiAlON). Patent Document 1 discloses that by adjusting the bonding part to Si _6-z Al _z O _z N _8-z (z value is 1.5 to 3.3), the CO gas oxidation resistance and alkali resistance of the refractory can be improved. , improving hot strength.

As disclosed in Patent Document 1, a refractory whose joint portion is adjusted to be SiAlON (Si _6-z Al _z O _z N _8-z : z value is 1.5 to 3.3) has good properties. It exhibits excellent CO gas oxidation resistance, alkali resistance, and hot strength. However, when SiAlON is heated in a low oxygen atmosphere, SiO ₂ produced by oxidation is reduced and SiO is produced. Therefore, when the refractory of Patent Document 1 is heated in a low oxygen atmosphere, SiO is generated at the bonding portion. Then, the generated SiO evaporates, reducing the strength of the refractory. Therefore, in refractories in which SiC particles are bonded by sialon, there is a need for a technology to suppress the generation of SiO during heating in a low oxygen atmosphere. The purpose of this specification is to realize a refractory in which SiC particles are bonded by sialon, and whose strength does not easily decrease even when heated in a low-oxygen atmosphere.

The first technology disclosed in this specification is a refractory in which aggregates containing SiC are bonded by bonding portions made of Si, Al, O, and N. In this refractory, the proportion of SiC in the refractory is 60% by mass or more and 90% by mass or less, and the proportion of each element constituting the joint is Si: 0.1% by mass or more and 1.1% by mass or less. , Al: 4% by mass or more and 21% by mass or less, O: 4.8% by mass or more and 19% by mass or less, and N: 7.2% by mass or more and 13.1% by mass or less.

A second technique disclosed in this specification is the refractory of the first technique, in which the proportion of Si element constituting the bonding portion may be 0.3% by mass or more and 0.8% by mass or less.

A third technology disclosed in this specification is the refractory of the second technology, in which the proportion of each element constituting the bonding portion is Al: 7.0% by mass or more and 7.6% by mass or less, O: N may be 4.8% by mass or more and 7.2% by mass or less, and N: 7.2% by mass or more and 7.8% by mass or less.

A fourth technique disclosed in this specification is a refractory according to any one of the first to third techniques, in which the peak intensity in X-ray diffraction of the bonded portion is equal to the peak intensity in X-ray diffraction of the SiC aggregate. On the other hand, it may be 4% or more and 30% or less.

A fifth technique disclosed in this specification is the refractory of the fourth technique, in which the peak intensity in X-ray diffraction of the bonded portion is 10% or more with respect to the peak intensity in X-ray diffraction of the SiC aggregate. It may be 30% or less.

A summary of Examples is shown.

The refractories disclosed in this specification are parts used in a firing furnace, such as a setter for placing an object to be fired, a spacer for ensuring a gap between the setters, a sagger, or a firing furnace. It can be used as the inner wall of In the refractory, aggregates containing SiC are bonded by bonding portions made of Al, Si, O, and N. The bond may be referred to as SiAlON. Sialon-bonded SiC is less likely to produce SiO ₂ through oxidation than, for example, silicon nitride (Si ₃ N ₄ )-bonded SiC, and as a result, SiO does not form even when heated in a low-oxygen atmosphere. It is difficult to generate SiO, and it is possible to suppress mass loss of the bonded portion due to evaporation of SiO. Specifically, SiC bonded with sialon generates mullite through oxidation, and the mullite acts as an oxidation protective film to suppress the generation of SiO ₂ . The refractory disclosed in this specification can suppress a decrease in strength even when used in a low oxygen atmosphere by suppressing a decrease in mass of a joint. Note that by suppressing the mass reduction (evaporation of SiO) of the joint, it is possible to prevent the evaporated gas from solidifying (sublimating) in the low-temperature part of the furnace and forming SiO deposits in the low-temperature part. By suppressing SiO deposits, maintenance work (deposit removal) for the firing furnace can be suppressed.

The proportion of SiC (aggregate) in the refractory may be 60% by mass or more and 90% by mass or less. By setting the proportion of aggregate to 60% by mass or more, the strength of the refractory can be improved. Furthermore, by setting the proportion of aggregate to 90% by mass, the volume of the bonding portion can be secured, and the aggregates can be firmly bonded. As a result, the strength of the refractory is improved. The proportion of SiC in the refractory may be 65% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more. It may be 85% by mass or more. Further, the proportion of SiC in the refractory may be 85% by mass or less, 80% by mass or less, 75% by mass or less, or 70% by mass or less. It may be 65% by mass or less.

The refractory disclosed herein is formed by firing aggregate (SiC), alumina (Al ₂ O ₃ ), and silica (SiO ₂ ) in a nitrogen atmosphere. As described above, the bonding portion is made of Al, Si, O, and N. The bond is formed by the reaction between alumina and silica under a nitrogen atmosphere. The proportions of each element constituting the bonding part are: Si: 0.1 mass% or more and 1.1 mass% or less, Al: 4 mass% or more and 21 mass% or less, O: 4.8 mass% or more and 19 mass% or less, N: may be 7.2% by mass or more and 13.1% by mass or less. By adjusting the ratio of each element in this manner, a refractory having high strength and high hypoxic resistance (suppression of mass loss in a low oxygen atmosphere) can be obtained.

Note that the proportion of the Si element constituting the bonding portion may be 0.3% by mass or more, 0.4% by mass or more, or 0.5% by mass or more. However, it may be 0.8% by mass or more. Further, the proportion of the Si element constituting the bonding portion may be 0.8% by mass or less, 0.5% by mass or less, or 0.4% by mass or less. However, it may be 0.3% by mass or less. Although the details will be described later, by adjusting the proportion of Si element constituting the bond to 0.3% by mass or more and 0.8% by mass or less, a refractory with even higher strength and even higher hypoxic resistance can be obtained. It has been experimentally confirmed that

Further, the proportion of Al element constituting the bonding portion may be 7.0% by mass or more, 7.5% by mass or more, or 7.6% by mass or more. However, it may be 7.8% by mass or more. Further, the proportion of Al element constituting the bonding portion may be 7.8% by mass or less, 7.6% by mass or less, or 7.5% by mass or less. However, it may be 7.0% by mass or less. Although the details will be described later, by adjusting the proportion of Al element constituting the bond to 7.0% by mass or more and 7.6% by mass or less, a refractory with even higher strength and even higher hypoxic resistance can be obtained. It has been experimentally confirmed that

Furthermore, the proportion of the O element constituting the bonding portion may be 7.1% by mass or more, or may be 7.2% by mass or more. Further, the proportion of O element constituting the bonding portion may be 7.8% by mass or less, 7.6% by mass or less, or 7.2% by mass or less. However, it may be 7.1% by mass or less. Although the details will be described later, by adjusting the proportion of O element constituting the joint to 4.8% by mass or more and 7.2% by mass or less, a refractory with even higher strength and even higher hypoxic resistance can be obtained. It has been experimentally confirmed that

Further, the proportion of the N element constituting the bonding portion may be 7.4% by mass or more, 7.5% by mass or more, or 7.6% by mass or more. However, it may be 7.8% by mass or more. Further, the proportion of N element constituting the bonding portion may be 7.8% by mass or less, 7.6% by mass or less, or 7.5% by mass or less. However, it may be 7.4% by mass or less. Although the details will be described later, by adjusting the proportion of N element constituting the joint to 7.2% by mass or more and 7.8% by mass or less, a refractory with even higher strength and even higher hypoxic resistance can be obtained. It has been experimentally confirmed that

As mentioned above, the proportion of SiC (aggregate) in the refractory may be 60% by mass or more and 90% by mass or less. In addition to mass measurement, the ratio of aggregate and bonding parts constituting the refractory can also be determined from the peak intensity ratio in X-ray diffraction. Specifically, when the refractory is subjected to X-ray diffraction, the peak intensity of the joint (the peak intensity that appears at 26.82°) is the same as the peak intensity (the peak intensity that appears at 34.11°) in the X-ray diffraction of the SiC aggregate. It may be 4% or more and 30% or less with respect to the sum of the peak intensity and the peak intensity appearing at 34.77°. The peak intensity ratio may be 5% or more, 10% or more, 12% or more, or 20% or more. Further, the peak intensity ratio may be 20% or less, 12% or less, 10% or less, or 5% or less. Although details will be described later, it has been confirmed through experiments that even higher strength and even higher hypoxic resistance can be obtained if the peak strength ratio of the joint to the aggregate is 10% or more and 30% or less.

A mixed raw material of SiC (aggregate), Al ₂ O ₃ and SiO ₂ was fired in a nitrogen atmosphere to create a refractory, and the bending strength and X-ray diffraction of the refractory were measured. Specifically, mixed raw materials with varying proportions of SiC, Al ₂ O ₃ and SiO ₂ were prepared and fired at 1450° C. for 3 hours in a nitrogen atmosphere to create refractories (samples 1 to 12). Note that sample 1 used a mixed raw material of SiC (aggregate) and Si, and sample 11 used a mixed raw material of SiC (aggregate) and Al ₂ O ₃ to create a refractory. In addition, as shown in FIG. 1, each sample was created using three types of SiC (SiCI, SiCII, SiCIII) with different particle size types. For each sample, the particle size type used is marked with a circle. SiCI contains 5% or less of SiC with a particle size of 2830 to 2000 μm, 15 to 30% of SiC with a particle size of 1000 to 500 μm, and the remainder is SiC with a particle size of 500 μm or less. SiCII contains 5% or less of SiC with a particle size of 500 to 250 μm, 30 to 50% of SiC with a particle size of 75 μm or less, and the remainder is SiC with a particle size of 250 to 75 μm. SiCIII contains 5% or less of SiC with a particle size of 45 to 15 μm, 40 to 70% of SiC with a particle size of 15 to 2 μm, and the remainder is SiC with a particle size of 2 μm or less. Samples 1-4, 9 and 12 used only SiCI. Samples 5 to 7, 10, and 11 used SiCI and SiCII. Sample 8 used SiCI and SiCIII. By changing the particle size type of SiC used, the proportion of SiC in the refractory was changed.

Each sample was subjected to XRD measurement, and the detected mineral was identified and the peak intensity ratio of the detected mineral (SiC, Sialon) was calculated. The results are shown in Figure 1. The peak intensity ratio of the detected minerals was calculated using the following formula (1). Note that the peak intensity of SiC was the sum of the peak intensity appearing at 34.11° and the peak intensity appearing at 34.77°. Moreover, the peak intensity of Sialon was defined as the peak intensity appearing at 26.82°.
Formula 1: Peak intensity ratio = (SiAlON peak intensity)/(SiC peak intensity) x 100

As shown in Figure 1, in the samples using SiC, Al ₂ O ₃ , and SiO ₂ as mixed raw materials (samples 2 to 10, 12), SiC, sialon, and corundum (aluminum oxide) were confirmed as detected minerals. . On the other hand, in sample 1 using SiC and Si as mixed raw materials (ie, the sample not using Al ₂ O ₃ and SiO ₂ ), SiC and silicon nitride were confirmed as detected minerals. In addition, in sample 12 using SiC and Al ₂ O ₃ as mixed raw materials (that is, a sample not using SiO ₂ ), SiC and corundum were confirmed as detected minerals. This result shows that SiC (aggregate), Al ₂ O ₃ and SiO ₂ are necessary as raw materials in order to manufacture a refractory in which SiC aggregates are bonded by sialon.

The bending strength of each sample was measured before and after Ar exposure treatment (heat treatment in a low oxygen atmosphere). In the Ar exposure treatment, each sample was heated at 1450° C. for 30 hours in an Ar atmosphere. The bending strength was measured by preparing a sample of 30 mm x 140 mm and 15 mm in thickness and performing a three-point bending strength test. FIG. 1 shows the bending strength before and after Ar exposure treatment, the bending strength change rate before and after Ar exposure treatment, and the mass change rate before and after Ar exposure treatment.

As shown in FIG. 1, it was confirmed that all of the samples in which sialon or silicon nitride was confirmed in XRD measurement (samples 1 to 10, 12) had high bending strength (10 MPa or more). It should be noted that no influence on the bending strength due to the difference in particle size of SiC (aggregate) was confirmed. In addition, the proportion of each element constituting the bonding portion is Si: 0.1% by mass or more and 1.1% by mass or less, Al: 4% by mass or more and 21% by mass or less, O: 4.8% by mass or more and 19% by mass or less. , N: 7.2% by mass or more and 13.1% by mass or less (Samples 4 to 10) have a strength change rate of -5% or less (strength decrease rate of 5% or less) before and after Ar exposure treatment. ) was confirmed. This result shows that if SiC (aggregate) is simply bonded with SiAlON, the strength of the refractory may decrease when the refractory is heated in a low oxygen atmosphere (Ar atmosphere). It shows. The proportion of each element constituting the bonding part is Si: 0.1% by mass or more and 1.1% by mass or less, Al: 4% by mass or more and 21% by mass or less, O: 4.8% by mass or more and 19% by mass or less, N. : It was confirmed that by adjusting the content to 7.2% by mass or more and 13.1% by mass or less, the decrease in strength of the refractory was suppressed even when heated in a low oxygen atmosphere. Note that Samples 4 to 10 had peak intensity ratios of 4% or more and 30% or less. Furthermore, it was confirmed that the value of the rate of change in strength and the value of the rate of mass change were approximately proportional.

In addition, samples (samples 5 to 9) in which the proportion of Si element constituting the bonding part is 0.3% by mass or more and 0.8% by mass or less have a strength change rate of "-3%" or less before and after Ar exposure treatment. It was confirmed that very good results could be obtained. Note that Samples 5 to 9 had peak intensity ratios of 10% or more and 30% or less. Note that Samples 6 and 7 had extremely high bending strength (25 MPa or more), and the rate of change in strength was "0%" before and after the Ar exposure treatment.

Samples 1 to 11 were comprehensively evaluated as refractories. Figure 1 shows the overall evaluation as a refractory. Specifically, samples with a bending strength of 25 MPa or more after the Ar exposure treatment and a strength change rate of "0%" before and after the Ar exposure treatment were rated as "A". In addition, samples with a bending strength of 25 MPa or more after Ar exposure treatment and a strength change rate of -3% or less before and after Ar exposure treatment (excluding strength change rate of 0%), or samples with a bending strength of 20 MPa after Ar exposure treatment A sample that was less than 25 MPa and had a strength change rate of "0%" before and after the Ar exposure treatment was given a "B rating". Samples with a bending strength of 10 MPa or more and less than 20 MPa after Ar exposure treatment and a strength change rate of "-5%" or less before and after Ar exposure treatment were rated as "C". In addition, samples that did not satisfy either or both of the bending strength after Ar exposure treatment of 10 MPa or more and less than 20 MPa and the strength change rate before and after Ar exposure treatment of "-5%" or less were rated as "D". Refractories rated A to C are at an acceptable level as refractories that are unlikely to lose strength even when heated in a low-oxygen atmosphere.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. Further, the technical elements described in this specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of the objectives has technical utility in itself.

Claims (5)

A refractory in which aggregates containing SiC are bonded by a bonding portion made of Si, Al, O and N,
The proportion of SiC in the refractory is 60% by mass or more and 90% by mass or less,
The proportion of each element constituting the bonding part is Si: 0.1% by mass or more and 1.1% by mass or less, Al: 4% by mass or more and 21% by mass or less, O: 4.8% by mass or more and 19% by mass or less, N: A refractory having a content of 7.2% by mass or more and 13.1% by mass or less. The refractory according to claim 1, wherein the proportion of Si element constituting the bonding portion is 0.3% by mass or more and 0.8% by mass or less. The proportions of each element constituting the bonding part are Al: 7.0% by mass or more and 7.6% by mass or less, O: 4.8% by mass or more and 7.2% by mass or less, N: 7.2% by mass or more7. The refractory according to claim 2, wherein the content is .6% by mass or less. The refractory according to any one of claims 1 to 3, wherein the peak intensity in X-ray diffraction of the bonded portion is 4% or more and 30% or less of the peak intensity in X-ray diffraction of the SiC aggregate. The refractory according to claim 4, wherein the peak intensity in X-ray diffraction of the bonded portion is 10% or more and 30% or less of the peak intensity in X-ray diffraction of the SiC aggregate.

Images