TW202116703A - Refractory material - Google Patents

Abstract

This refractory material comprises: a Si-SiC-material substrate that includes SiC particles as a main component and also includes metal Si disposed between the SiC particles; and a glass layer that covers a surface of the Si-SiC-material substrate and that includes SiO2 as a main component. The mass ratio of the glass layer to the Si-SiC-material substrate of this refractory is 0.001-5 mass%.

Description

Refractory

This application claims priority based on Japanese Patent Application No. 2019-182486 filed on October 2, 2019. The entire content of the above-mentioned application is cited in this specification by reference. This manual discloses the technology about refractories.

As a member used in a high-temperature environment such as in a sintering furnace, a refractory having heat resistance is used. JP 2008-94652 A (hereinafter referred to as Patent Document 1) discloses a refractory using a Si—SiC base material containing SiC particles as a main body and containing metallic Si between the SiC particles. The Si-SiC refractory has excellent thermal conductivity, so it is difficult to produce a temperature difference in the refractory. Therefore, Si-SiC refractories have the advantage of being able to suppress damage caused by thermal stress. In addition, the Si-SiC base material has excellent heat resistance and fire resistance, and is expected to be used as a material for manufacturing refractories.

[The problem to be solved by the invention]

The Si-SiC refractory is manufactured by bringing metal Si into contact with the SiC formed body after the SiC formed body is produced, and heated under low pressure in an inert gas atmosphere. On the surface of the heated Si—SiC refractory, the Si component remains, that is, the metallic Si or Si compound that is not impregnated in the SiC molded body. Therefore, in the Si-SiC refractory, after the metal Si is impregnated in the SiC formed body, the step of removing the Si component remaining on the surface is necessary. When the Si component is removed from the surface of the Si-SiC refractory, the surface of the Si-SiC refractory may be damaged, and cracks may be generated from the damage as a starting point. If cracks are generated in the Si-SiC refractory, the strength of the Si-SiC refractory may be reduced. This specification provides techniques for suppressing the decrease in the strength of Si-SiC refractories. [Means to solve the problem]

The refractory disclosed in this specification may include a Si-SiC base material and a glass layer. The Si-SiC base material may have SiC particles as a main body, and metal Si may be contained between the SiC particles. The glass layer may be mainly composed of SiO ₂ covering the surface of the Si-SiC substrate. In such a refractory, the mass ratio of the glass layer to the Si-SiC base material may be 0.001% by mass or more and 5% by mass or less.

[Form to implement invention]

(Refractory) The refractory disclosed in this specification is the inner wall of the firing furnace and other components that constitute the firing furnace, or as a member used in the firing furnace such as racks and setters. use. Although not particularly limited, the refractory disclosed in the present invention can be suitably used in an environment with a maximum temperature of 500 to 1350°C. The shape of the refractory may be flat, box, column, block, cylindrical, or the like. The thickness of the refractory can be 0.1-20mm. The refractory may include a Si-SiC-based substrate and a glass layer covering the surface of the Si-SiC-based substrate. In addition, the refractory previously produced with a Si-SiC base material has a step of removing Si (or Si compound) remaining on the surface after forming the Si-SiC fired body. Therefore, even if a glass layer is formed on the surface of the conventional refractory during the production process of the Si-SiC refractory, the glass layer is removed in the step of removing Si on the surface. That is, the conventional refractory made of Si-SiC base material is not provided with a glass layer on the surface.

By coating the surface of the Si-SiC base material with the glass layer, it is possible to prevent the refractory from being damaged starting from the recesses (damages etc.) on the surface of the Si-SiC base material. Specifically, by coating the surface of the Si-SiC substrate with a glass layer, when stress is applied to the surface of the substrate due to thermal expansion and contraction of the Si-SiC substrate, it is possible to prevent the stress from concentrating on the recesses on the substrate surface , And can suppress the damage of the refractory.

(Si-SiC base material) The Si-SiC base material may have SiC particles as a main body, and metal Si may be contained between the SiC particles. In addition, "mainly SiC particles" means that the ratio (mass%) of SiC particles occupying the Si-SiC substrate is greater than 50% by mass. Although not limited, the proportion of SiC particles occupying the Si-SiC substrate may be 55% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more. The size (average particle diameter) of the SiC particles may be 5 μm or more and 10 μm or less. If the size of the SiC particles is too small, it becomes difficult for metallic Si to be introduced between the SiC particles, and if the size of the SiC particles is too large, the strength of the Si-SiC substrate will decrease. The size (average particle diameter) of the SiC particles may be 10 μm or more, 20 μm or more, or 30 μm or more. In addition, the size of the SiC particles may be 80 μm or less, 70 μm or less, or 60 μm or less.

The proportion (mass %) of metallic Si occupying the Si-SiC base material may be 5-40% by mass. If the proportion of metal Si occupying the Si-SiC substrate is too small, the amount of voids between the SiC particles will increase (the porosity of the Si-SiC substrate becomes higher), and the strength of the Si-SiC substrate may sometimes decrease reduce. On the other hand, if the proportion of metal Si occupying the Si-SiC base material is too large, cracks are likely to occur during use (when the refractory is exposed to high temperatures), and the strength of the Si-SiC base material may sometimes decrease. The proportion of metal Si occupying the Si-SiC substrate is determined by the proportion of SiC particles occupying the Si-SiC substrate. Specifically, in order to make the apparent porosity of the Si-SiC base material 5% or less, metallic Si is impregnated between SiC particles. By reducing the apparent porosity of the Si-SiC base material, a refractory with high strength and excellent corrosion resistance can be obtained. In addition, the apparent porosity of the Si-SiC substrate is more preferably 2% or less, and particularly preferably 1% or less.

Concavities and convexities can be formed on the surface of the Si-SiC substrate. By forming irregularities on the surface of the Si-SiC base material, it is possible to suppress the peeling of the glass layer from the surface of the Si-SiC base material. In addition, the surface roughness Rz (ISO1997, JIS B 0601:2001) of the unevenness of the surface of the Si-SiC substrate may be 1 μm or more and 150 μm or less. By making the surface roughness Rz of the concavities and convexities 1 μm or more, the adhesion between the Si-SiC substrate and the glass layer can be improved. On the other hand, by setting the depth Rz of the unevenness to 150 μm or less, it is possible to suppress the unevenness from becoming the starting point of cracks. The surface roughness Rz of the concavities and convexities may be thicker than the thickness (average thickness) of the glass layer. For example, it may be 5 μm or more, 10 μm or more, 30 μm or more, or 50 μm or more. In addition, the surface roughness Rz of the unevenness may be 120 μm or less, may be 100 μm or less, may be 80 μm or less, or may be 60 μm or less.

As described above, in the Si-SiC refractory, after the metal Si is impregnated in the SiC formed body, there is a step of removing Si remaining on the surface. The unevenness on the surface of the Si-SiC substrate may be formed in the step of removing the Si component from the surface of the Si-SiC substrate, or may be performed separately from the step of removing the Si component. As described above, previously, in the removal step of the Si component, the surface of the Si—SiC base material was sometimes damaged, and cracks were generated starting from the damage described above. The technique disclosed in this specification can also be understood as a technique for suppressing the generation of cracks in the fired product instead of removing the damage generated in the Si component removal step.

(Glass layer) The glass layer can cover the entire surface of the Si-SiC substrate. Although not particularly limited, the thickness of the glass layer may be 0.1 μm or more and 150 μm or less. By setting the thickness of the glass layer to 0.1 μm or more, the effect of suppressing the occurrence of cracks can be sufficiently obtained. In addition, by making the thickness of the glass layer 150μm or less, based on the difference in the coefficient of thermal expansion between the Si-SiC substrate and the glass layer, a force (stress) is applied from the glass layer to the Si-SiC substrate to cause cracks. Be restrained. The thickness (average thickness) of the glass layer is preferably thinner than the surface roughness Rz of the concavities and convexities on the surface of the Si-SiC substrate. For example, it may be 100 μm or less, 60 μm or less, or 40 μm or less. In addition, the thickness of the glass layer may be 0.5 μm or more, 1 μm or more, 5 μm or more, or 10 μm or more.

The mass ratio of the glass layer with respect to the Si-SiC base material may be 0.001 mass% or more and 5 mass% or less. As long as it is in this range, the strength of the refractory can be improved and the generation of cracks can be suppressed. When the mass ratio is less than 0.001% by mass, it becomes difficult to obtain the effect of suppressing the generation of cracks. When the mass ratio exceeds 5% by mass, the ratio of the glass layer to the Si-SiC base material is too high, and it becomes difficult to obtain a high-strength refractory. The mass ratio of the glass layer to the Si-SiC substrate may be 0.003% by mass or more, 0.02% by mass or more, or 0.08% by mass or more. In addition, the mass ratio of the glass layer to the Si-SiC base material may be 3% by mass or less, and may be 1% by mass or less.

The mass ratio of the glass layer to the Si-SiC substrate can be calculated from the mass of the substrate before the formation of the glass layer and the mass of the entire refractory after the formation of the glass layer. In addition, the mass ratio of the glass layer with respect to the Si-SiC substrate can be calculated by the image analysis of SEM, CT, etc., in the refractory Si-SiC substrate and the volume of the glass layer, and the Si-SiC substrate The density of the material and the glass layer is calculated from the mass of the Si-SiC base material and the glass layer, and is calculated from the obtained masses of both.

The glass layer may be mainly composed of SiO ₂ and may contain one or more elements of Al, Ca, Fe, Na, K, Mg, Sr, and Ba. That is, the glass layer may also be SiO ₂ alone, and may be composed of 50% by mass or more of SiO ₂ and elements of Al, Ca, Fe, Na, K, Mg, Sr, and Ba (hereinafter referred to as accessory elements) or It is composed of a compound of an accessory element (for example, an oxide of an accessory element). By including auxiliary component elements, the temperature during glass formation can be lowered, and the formation time can be shortened. That is, the glass layer containing the sub-component element can simplify the formation process compared with the glass layer not containing the sub-component element. In addition, the glass layer preferably contains one or more elements of Al, Ca, Fe, Na, and K (hereinafter referred to as the first sub-component element) among the above-mentioned sub-component elements. The first sub-component element (compound of the first sub-component element) can be obtained relatively easily, and it is easy to handle because it is chemically stable. In addition, the accessory component element may exist as a compound in the glass layer, and it is particularly preferable to exist as an oxide.

The glass layer may be formed by heating (sintering) the Si-SiC substrate in an oxidizing atmosphere after forming the unevenness on the surface of the Si-SiC substrate. _{The SiO 2} of the main material of the glass layer may be an oxidized product of a part of Si constituting the Si-SiC substrate, or it may be a raw material for the glass layer containing Si arranged on the surface of the Si-SiC substrate and contained in The oxidized product of the Si component of the raw material for the glass layer. In addition, when the glass layer contains the above-mentioned subsidiary component element, the raw material for the glass layer may contain the subsidiary component element. The raw material for the glass layer may be a solid such as a powder or a granule, or a fluid such as a paste or a liquid. In addition, in the case of using a fluid glass layer raw material, after arranging (coating) the glass layer raw material on the surface of the Si-SiC substrate, the glass layer may be heated (fired) in an oxidizing atmosphere. The layer is dried with raw materials.

The heating (sintering) conditions when forming the glass layer depend on the thickness of the desired glass layer, the components contained in the glass layer, the presence or absence of the raw material for the glass layer, and the type of the raw material for the glass layer. It can be adjusted to, for example, 900~ 1 to 5 hours at 1350°C. In addition, as the oxidizing gas introduced into the heating device (sintering furnace), oxygen, ozone, carbon dioxide, etc. can be used.

When the shape of the refractory material is a plate shape or a box shape, the refractory material may be a firing carrier plate for mounting the fired object such as an electronic component in a heating furnace. When using a refractory as a carrier plate for firing, in order to suppress the reaction between the fired object and the refractory, a surface coating may be provided on the glass layer. The surface coating can be formed of a material with low reactivity to the burned object, and different materials can be selected according to the type (material) of the burned object. For example, when the fired object is a ceramic capacitor composed of barium titanate, it is preferable to select a zirconium oxide compound or yttrium oxide compound (Y ₂ O ₃ ) that has low reactivity to barium titanate as the surface coating. . In the case of selecting a zirconia compound as a surface coating, considering the reactivity to the burned object, a suitable choice is made of stabilized zirconia stabilized with _{calcium oxide (CaO) or yttrium oxide (Y 2} O _{3 ),} The most suitable zirconium oxide among zirconium oxide compounds composed of at least one of BaZrO ₃ and CaZrO _{3 may be sufficient.}

In addition, depending on the type (material) of the electronic component, a spray coating containing a eutectic of alumina and zirconia can also be used as a surface coating. In addition, the method of forming the surface coating is not particularly limited, and a suitable optimum method can be adopted, for example, spraying or spray coating. In addition, in the case of using a zirconia compound as a surface coating, in order to prevent the occurrence of peeling due to the difference in thermal expansion between the Si-SiC base material and the zirconia surface coating, the glass layer and the zirconia surface coating may be peeled off. Between the surface coatings, an intermediate layer of alumina, mullite, etc. is arranged.

[Example] (First embodiment: manufacturing steps of refractory) With reference to Figure 1, the manufacturing steps of the refractory will be described. In addition, the fired body of the Si-SiC base material is known including the production method. Therefore, in the following description, the step of forming a glass layer on the surface of the Si-SiC substrate is mainly described.

First, a flat sintered body of Si-SiC substrate is produced (stage S1), the Si component remaining on the surface of the Si-SiC sintered body is removed, and unevenness is formed on the surface of the Si-SiC sintered body (Stage S2). The apparent porosity of the Si-SiC fired body is 2% or less. The surface of the Si-SiC fired body was measured using a surface roughness meter (manufactured by Mitutoyo Corporation: SJ-210) to measure the surface roughness Rz (ISO1997, JIS B 0601:2001). The surface roughness Rz of the Si-SiC fired body was 29 μm.

Next, the raw material for the glass layer is applied to the surface of the Si-SiC fired body, and after the raw material for the glass layer is dried, the Si-SiC fired body is fired (stage 3). As a raw material for the glass layer, a 10% NaCl aqueous solution was used. Specifically, a 10% NaCl aqueous solution was applied to the entire surface of the Si-SiC fired body at 10 g/m ² and dried in an air atmosphere at 100°C for 1 hour to fix the glass layer raw material to Si-SiC The surface of the sintered body. Next, the Si-SiC fired body is placed in the firing furnace in an atmospheric atmosphere, and the temperature is raised to 1300°C at a heating rate of 100°C/h, kept at 1300°C for 5 hours, and the temperature is naturally cooled to room temperature to produce a refractory . It was confirmed by visual inspection and a microscope (SEM) that the glass layer was formed on the entire surface of the refractory.

Figure 2 shows the SEM image near the surface of the refractory. As shown in Figure 2, the glass layer covers the entire surface of the Si-SiC fired body. The average thickness of the glass layer is 6 μm, which is thinner than the surface roughness Rz of the Si-SiC fired body. Therefore, irregularities were also confirmed on the surface of the refractory (the surface of the glass layer). In addition, the layer provided on the upper part of the glass layer is a resin used when making a sample for imaging an SEM image.

(Second Example: Strength Evaluation of Refractories) A plurality of roller-shaped refractories were produced, and the strength of the refractories was evaluated. First, after the above-mentioned steps S1 and S2, a drum-shaped Si-SiC fired body having an outer diameter of 42 mm, an inner diameter of 30 mm, and a length of 1000 mm is obtained. The apparent porosity of the obtained Si-SiC fired body was 2% or less. Next, the Si-SiC sintered body is placed in an atmospheric sintering furnace, the temperature is raised to a specified temperature at a heating rate of 100°C/h, and the temperature is maintained at the specified temperature for a specified time, so that the substrate (Si-SiC Oxidize the Si of the high-quality fired body) to deposit the glass layer on the surface of the substrate and allow it to naturally cool down to room temperature to make refractories (samples 1-12).

Sample 2 uses 1200°C as the designated temperature and 1 hour as the designated time. For samples 3 to 12, the specified temperature and/or specified time were changed relative to the sample 2, and the amount of the glass layer deposited on the surface of the substrate was changed. Specifically, for samples 3 to 5, the specified temperature and/or the specified time are made shorter than that of the sample 2. On the other hand, for samples 6 to 12, the specified temperature and/or the specified time were increased relative to that of the sample 2. In addition, after the sample 1 obtained the Si-SiC-based fired body, firing in the air atmosphere was not performed (the glass layer was not deposited).

The obtained refractories were visually and microscope (SEM) confirmed that the glass layer was formed on the entire surface of the refractories (except for sample 1). Next, with respect to samples 2 to 12, the mass ratio (W) of the glass layer to the Si-SiC base material was measured. The mass ratio of the glass layer to the Si-SiC substrate is to measure the mass (W ₀ ) of the Si-SiC substrate (Si-SiC fired body) before the glass layer is formed, and the refractory after the glass layer is formed The mass (W ₁ ) of, and calculated using the following formula (1). The mass ratio (W) of each sample is shown in Figure 3. Formula (1): W=((W ₁ −W ₀ )/W ₀ )×100

(Strength evaluation) Measure the bending strength of samples 1-12. The bending strength was measured by placing the obtained sample on a span table with a span of 600 mm, and performing a 3-point bending test at room temperature. The results of the bending strength of each sample are shown in Fig. 3. As shown in Figure 3, it was confirmed that the samples (samples 2 to 11) in which the mass ratio of the glass layer to the Si-SiC substrate is 0.001% by mass to 5% by mass can achieve high strength of 130 MPa or more. In particular, it was confirmed that samples with a mass ratio of 0.003% by mass to 3% by mass (samples 2, 4 to 11) can obtain higher strength (150 MPa or more).

Although the specific examples of the present invention have been described in detail above, 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 exemplified above. In addition, the technical elements described in this specification or the drawings are used alone or in various combinations to achieve technical utility, and are not limited to the combinations described in the claims at the time of application. In addition, the techniques exemplified in this specification or the drawings can achieve multiple numbers at the same time, and achieving one of them has technical utility in itself.

S1, S2, S3: stage

[Figure 1] Shows a flow chart for the manufacture of refractories. [Figure 2] A SEM image near the surface of the refractory is shown. [Figure 3] shows the relationship between the mass ratio of the glass layer to the Si-SiC substrate and the strength.

S1, S2, S3: stage

Claims (8)

A refractory material comprising: a Si-SiC base material with SiC particles as the main body, and metal Si between the SiC particles; and a glass layer with SiO ₂ covering the surface of the aforementioned Si-SiC base material as the main body, wherein the aforementioned The mass ratio of the glass layer with respect to the aforementioned Si-SiC base material is 0.001 mass% or more and 5 mass% or less. The refractory according to claim 1, wherein the thickness of the glass layer is thinner than the depth of the unevenness on the surface of the Si-SiC base material. The refractory according to claim 1 or 2, wherein the surface roughness Rz of the unevenness of the surface of the Si-SiC substrate is 0.1 μm or more and 150 μm or less. The refractory according to any one of claims 1 to 3, wherein the aforementioned glass layer contains at least one element selected from Al, Ca, Fe, Na, K, Mg, Sr, and Ba. The refractory according to claim 4, wherein the glass layer contains at least one element selected from Al, Ca, Fe, Na, and K. The refractory according to any one of claims 1 to 5, wherein the mass ratio of the glass layer to the Si-SiC base material is 0.003% by mass to 3% by mass. The refractory according to any one of claims 1 to 6, wherein the apparent porosity of the aforementioned Si-SiC base material is 5% or less. The refractory according to any one of claims 1 to 7, wherein a surface coating is provided on the aforementioned glass layer.

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