Ceramic Components

Abstract

A ceramic member according to the present disclosure has a substrate made of ceramic. The substrate has, on a front surface section thereof, a boron-containing layer containing a larger amount of boron than the amount of boron inside the substrate.

Description

[Technical field]

[0001] The present disclosure relates to ceramic components. [Background technology]

[0002] Ceramic members are widely used as various parts because of their characteristics such as high strength, hardness, heat resistance, and chemical resistance. In addition, ceramic members are used, for example, as heat-resistant members (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-132657 Summary of the Invention

[0004] A ceramic member according to one embodiment of the present disclosure has a substrate made of a boron-containing ceramic, and a boron-containing layer on a surface of the substrate, the boron-containing layer containing more boron than the boron content in the interior of the substrate. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic perspective view of a ceramic member according to an embodiment. [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view of a ceramic member according to an embodiment. [Diagram 3] FIG. 3 is a schematic cross-sectional view of a ceramic member according to an embodiment. [Figure 4] FIG. 4 is a graph showing the change in boron content between positions P1 and P2 shown in FIG. [Diagram 5] FIG. 5 is a graph showing the change in boron content between positions P3 and P4 shown in FIG. [Figure 6]FIG. 6 is a graph showing another example of the change in boron content between positions P1 and P2 shown in FIG. [Figure 7] FIG. 7 is a schematic vertical cross-sectional view showing another example of the ceramic member according to the embodiment. [Figure 8] FIG. 8 is a graph showing the change in boron content between positions P5 and P6 shown in FIG. [Figure 9] FIG. 9 is a schematic vertical cross-sectional view showing another example of the ceramic member according to the embodiment. [Figure 10] FIG. 10 is a graph showing the change in boron content between positions P7 and P8 shown in FIG. [Figure 11] FIG. 11 is a schematic vertical cross-sectional view of a ceramic member according to another embodiment. [Figure 12] FIG. 12 is a schematic vertical cross-sectional view of a ceramic member according to another embodiment. [Figure 13] FIG. 13 is a table showing the results of tests on thermal shock resistance for lots L11 to L16. [Figure 14] FIG. 14 is a graph showing the change in boron content in the thickness direction of the side wall portion of lot L14. [Figure 15] FIG. 15 is a graph showing the change in boron content in the thickness direction of the bottom wall of lot L14. [Figure 16] FIG. 16 is a graph showing the change in boron content in the thickness direction of the corner portion of lot L14. [Figure 17] FIG. 17 is a table summarizing the test results in the preliminary experiments. [Figure 18] FIG. 18 is a graph showing the test results of three-point bending strength in a preliminary experiment. [Figure 19] FIG. 19 is a graph showing test results of the average thermal expansion coefficient in a preliminary experiment. [Figure 20] FIG. 20 is a graph showing the test results of thermal shock resistance in a preliminary experiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Hereinafter, a form for carrying out a ceramic member according to the present disclosure (hereinafter, referred to as an "embodiment") will be described in detail with reference to the drawings. Note that the ceramic member according to the present disclosure is not limited to this embodiment. In addition, each embodiment can be appropriately combined within a range that does not cause a contradiction in the processing content. In addition, the same parts in each of the following embodiments are given the same reference numerals, and duplicated explanations will be omitted.

[0007] In addition, in the embodiments described below, expressions such as "constant", "orthogonal", "vertical" and "parallel" may be used, but these expressions do not necessarily mean "constant", "orthogonal", "vertical" and "parallel" strictly. In other words, each of the above expressions allows for deviations due to, for example, manufacturing accuracy and installation accuracy.

[0008] Ceramic members having higher strength are desired. For example, ceramic members used as heat-resistant members, such as ceramic members exposed to high-temperature molten metals and members used in combustion chamber walls and fuel injection nozzles of internal combustion engines, are desired to have excellent thermal shock resistance. Under these circumstances, there is a demand for ceramic members having excellent strength.

[0009] Fig. 1 is a schematic perspective view of a ceramic member 1 according to an embodiment. Fig. 2 is a schematic vertical cross-sectional view of the ceramic member 1 according to an embodiment. Fig. 3 is a schematic horizontal cross-sectional view of the ceramic member 1 according to an embodiment.

[0010] The longitudinal cross-sectional view shown in Fig. 2 corresponds to a cross-section taken along the line II-II in Fig. 3. That is, Fig. 2 shows a cross-section perpendicular to the first wall portion 11 and the second wall portion 12. The transverse cross-sectional view shown in Fig. 3 corresponds to a cross-section taken along the line III-III in Fig. 2. That is, Fig. 3 shows a cross-section perpendicular to the wall surface of the first wall portion 11 and parallel to the second wall portion 12.

[0011] 1 to 3, the ceramic member 1 according to the embodiment may have a container shape. Note that, as will be described later, the shape of the ceramic member 1 is not limited to this example, and may be any shape such as a plate shape, a cylinder shape, a frame shape, or a column shape.

[0012] The ceramic member 1 according to the embodiment has a substrate 10 made of ceramic. The ceramic constituting the substrate 10 may be, for example, aluminum oxide ceramics, silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics, or the like.

[0013] When the substrate 10 is made of aluminum oxide ceramics, it is relatively inexpensive among ceramics, including the cost of raw materials and the cost of production, and at the same time has excellent mechanical properties.

[0014] Here, aluminum oxide ceramics refers to ceramics that contain 70 mass % or more of aluminum oxide out of 100 mass % of all components constituting the ceramics.

[0015] The material of the substrate 10 can be confirmed, for example, by the following method. First, the substrate 10 is measured using an X-ray diffraction device (XRD), and the obtained 2θ (2θ is the diffraction angle) value is compared with the JCPDS card. Next, an inductively coupled plasma (ICP) emission spectrometer or an X-ray fluorescence analyzer (XRF) is used to quantitatively analyze aluminum (Al). If the content of Al measured by ICP or XRF is converted to aluminum oxide (Al2O3) and is 70 mass% or more, the material of the substrate 10 is aluminum oxide ceramics.

[0016] The substrate 10 may be a polycrystalline body having a porosity of 5% or less. When the material of the substrate 10 is aluminum oxide ceramics, the bulk density of the substrate 10 is 3.2 g / cm 3 In this manner, the ceramics constituting the base 10 may be dense ceramics.

[0017] 2, in this specification, the first wall portion 11 is divided into three equal parts in the thickness direction, and the region located on the inner wall side is referred to as the inner wall side R1, and the region located on the outer wall side is referred to as the outer wall side R3. The first wall portion 11 is divided into three equal parts in the thickness direction, and the region between the inner wall side R1 and the outer wall side R3 is referred to as the inner side R2. Similarly, the second wall portion 12 is divided into three equal parts in the thickness direction, and the regions closest to the inner wall side are referred to as the inner wall side R1, the inner side R2, and the outer wall side R3.

[0018] The substrate 10 contains boron (B). Specifically, as shown in FIG. 2 and FIG. 3, the substrate 10 has a boron-containing layer 20 on the surface. The boron-containing layer 20 is a region having a higher boron content than the inside R2 of the substrate 10. The boron-containing layer 20 may be referred to as a "high boron content region". The substrate 10 may have a first surface and a second surface located opposite to the first surface. The substrate 10 may also have a third surface located between the first surface and the second surface. In the example of FIG. 2, the first surface 11a may be the inner wall surface 11a of the first wall portion 11. The second surface 11b may be the outer wall surface 11b of the first wall portion 11. The third surface 11c may be the upper surface 11c of the first wall portion 11.

[0019] The substrate 10 may have a first boron-containing layer 21 and a second boron-containing layer 22 as the boron-containing layer 20. The first boron-containing layer 21 may be located on an inner wall surface side portion R1 of the substrate 10 (see FIG. 2). The second boron-containing layer 22 may be located on an outer wall surface side portion R3 of the substrate 10 (see FIG. 2). When the boron content of the first boron-containing layer 21 is defined as the first boron content and the boron content of the second boron-containing layer 22 is defined as the second boron content, the first boron content and the second boron content may be different.

[0020] The boron content of the boron-containing layer can be confirmed, for example, by the following method: A piece of the boron-containing layer is cut out, and quantitative analysis of boron (B) is performed using an inductively coupled plasma (ICP) emission spectrometer or an X-ray fluorescence spectrometer (XRF).

[0021] Fig. 4 is a graph showing the change in boron content between position P1 and position P2 shown in Fig. 3. The boron content specifically means the content of boron calculated as B2O3.

[0022] Position P1 is an arbitrary point on the outer wall surface of first wall portion 11. Position P2 is a point on the inner wall surface of first wall portion 11, and is located on the opposite side to position P1 across first wall portion 11. Fig. 4 shows a graph in which the horizontal axis represents the position in the thickness direction of base 10 (position P1 to position P2) and the vertical axis represents the boron content.

[0023] As shown in FIG. 4, the boron content in the boron-containing layer 20 (the first boron-containing layer 21 and the second boron-containing layer 22) is greater than the boron content in the inner portion R2 of the substrate 10. This makes it possible to obtain a ceramic member 1 that is excellent in strength and thermal shock resistance. In a ceramic sintered body, when the boron content is greater, the thermal expansion coefficient tends to be smaller than when the boron content is smaller. Therefore, the ceramic member of this embodiment has different thermal expansion coefficients between the surface portion and the interior. Since the surface portion contains more boron than the interior, the thermal expansion coefficient of the surface portion is smaller than the thermal expansion coefficient of the interior. Therefore, during the process of cooling the ceramic member after firing in the manufacturing process of the ceramic member, a state occurs in which the contraction rates are different between the surface portion and the interior. In the surface portion with smaller thermal expansion, compressive stress occurs. As a result, the ceramic member of this embodiment has high strength.

[0024] Furthermore, the ceramic member 1 of this embodiment has excellent thermal shock resistance. This will be described using as an example the process from when the ceramic member 1 is suddenly heated by a molten metal or the like and the temperature starts to rise until the temperature of the ceramic member 1 becomes uniform.

[0025] The inside of the base 10 is less susceptible to heating than the surface side, so the temperature inside the base 10 becomes lower than that of the surface side. In this process, if the thermal expansion coefficients of the surface and the inside are the same, the surface side, which has a higher temperature, will expand more than the inside, generating tensile stress inside. As a result, there is a risk of cracks and breakage occurring from the inside.

[0026] In contrast, when the boron content in the inside R2 of the base 10 is less than that of the surface side (the inner wall surface side R1 and the outer wall surface side R3) as in the ceramic member 1 according to the embodiment, the thermal expansion coefficient of the inside R2 is greater than that of the surface side. As a result, the thermal expansion difference between the surface and the inside is smaller than when the thermal expansion coefficients of the surface and the inside are the same, so the tensile stress applied to the inside R2 during the process of the ceramic member 1 suddenly increasing in temperature is reduced. Therefore, even if the temperature of the ceramic member 1 according to the embodiment increases suddenly due to molten metal or the like, cracks and breaks are unlikely to occur in the inside R2 of the base 10. In addition, in a ceramic sintered body, when the boron content is high, the Young's modulus tends to be smaller than when the boron content is low. Therefore, the ceramic member of the present embodiment may have different Young's moduli between the surface and the inside. In such a case, since the surface contains more boron than the inside, the Young's modulus of the surface is smaller than that of the inside. The surface with a small Young's modulus is easily deformed when stress is applied, so that it has high durability against impact. This provides the ceramic member of this embodiment with excellent thermal shock resistance.

[0027] Furthermore, when the thermal expansion coefficient of the inner wall surface is smaller than that of the interior R2, even if the heat-resistant member 1 is rapidly heated from the inner wall surface side, the thermal expansion of the inner wall surface side is reduced, making it difficult for cracks to occur that originate from the inside.

[0028] Thus, the ceramic member 1 having the boron-containing layer 20 has high thermal shock resistance.

[0029] The base 10 may have, for example, a plurality of (four in this case) first walls 11 and one second wall 12 as shown in FIG. 2. The base 10 may have an opening 13 on the opposite side of the second wall 12 (at a position facing the second wall 12). In the embodiment, the second wall 12 constitutes the bottom wall of the base 10. However, this is not limited to this, and the second wall 12 may constitute the upper wall of the base 10. That is, the ceramic member 1 may be used in a position upside down from that in FIG. 1. The ceramic member 1 may be used with the opening 13 facing the horizontal direction. In this way, the position of the ceramic member 1 is not particularly limited.

[0030] The second wall portion 12 may have a quadrangular shape in a plan view. Here, the quadrangular shape is not limited to a rectangular shape as shown in the figure, and may be a square shape. In addition, the four first walls 11 may form side walls of the base body 10 and be continuous with the second wall portion 12.

[0031] The shape of the second wall portion 12 in a plan view is not limited to a quadrangle, and may be, for example, a polygonal shape other than a quadrangle, or may be a circle or an ellipse.

[0032] Furthermore, the base 10 may have a corner located between two adjacent first wall portions 11, or a corner located between the first wall portion 11 and the second wall portion 12. The corners may be located on the inner wall surface side and the outer wall surface side of the base 10. That is, the base 10 may have an inner wall surface side corner 14 which is a first corner located on the inner wall surface side, and an outer wall surface side corner 15 which is a second corner located on the outer wall surface side.

[0033] Furthermore, the base 10 may have a through hole, a recess, a protrusion, or the like, in the first wall portion 11 or the second wall portion 12, for example.

[0034] The ceramic member 1 according to the embodiment may be exposed to a high-temperature environment. The ceramic member 1 according to the embodiment may be used as a heat-resistant member. Specifically, the ceramic member 1 according to the embodiment may contain a high-temperature substance. For example, the ceramic member 1 may be used as a container for molten metal. In addition, the ceramic member 1 may be used as, for example, a ladle for scooping up molten metal, or as a crucible.

[0035] In the base 10 according to the embodiment, the boron content in the first boron-containing layer 21 is different from the boron content in the second boron-containing layer 22. For example, as shown in FIG. 4, the boron content in the first boron-containing layer 21 may be higher than the boron content in the second boron-containing layer 22.

[0036] Specifically, the first boron-containing layer 21 is, for example, a region of the inner wall surface side portion R1 from the inner wall surface of the base 10 to a position two-thirds of the way in the thickness direction of the base 10. The first boron-containing layer 21 is divided into two equal parts in the thickness direction of the base 10, and the region on the inner wall surface side of the base 10 is defined as the surface layer portion 21a of the first boron-containing layer 21, and the other region is defined as the interior 21b of the first boron-containing layer 21.

[0037] Similarly, the second boron-containing layer 22 is, for example, a region of the outer wall surface side portion R3 extending from the outer wall surface of the base 10 to a position two-thirds of the way in the thickness direction of the base 10. In addition, the second boron-containing layer 22 is divided into two equal parts in the thickness direction of the base 10, with the region on the outer wall surface side of the base 10 being the surface layer portion 22a of the second boron-containing layer 22 and the other region being the interior 22b of the second boron-containing layer 22.

[0038] 4, the maximum value (C5) of the boron content in the first boron-containing layer 21 may be greater than the maximum value (C3) of the boron content in the second boron-containing layer 22. In addition, the minimum value (C4) of the boron content in the first boron-containing layer 21 may be greater than the maximum value (C3) of the boron content in the second boron-containing layer 22. In addition, the average value of the boron content in the first boron-containing layer 21 may be greater than the average value of the boron content in the second boron-containing layer 22.

[0039] In this way, the boron content in the first boron-containing layer 21 in terms of B2O3 may be greater than the boron content in the second boron-containing layer 22 in terms of B2O3. In other words, the ceramic member 1 according to the embodiment may have different boron contents depending on the position. As described above, when the boron content is high, the strength and thermal shock resistance of the ceramic member 1 in that portion are high. In other words, by having a high boron content in the portion requiring strength and thermal shock resistance, it is possible to provide a ceramic member 1 that is less likely to break. In other words, the ceramic member 1 according to the embodiment has excellent strength and thermal shock resistance in parts.

[0040] 4, the ceramic member 1 according to the embodiment may contain boron throughout the entire thickness direction of the base 10. Such a ceramic member 1 has high mechanical strength.

[0041] Fig. 5 is a graph showing the change in boron content between positions P3 and P4 shown in Fig. 2. Position P4 is an arbitrary point on an inner wall surface side corner 14, which is a first corner located between the first wall portion 11 and the second wall portion 12. Position P3 is a point on an outer wall surface side corner 15, which is a second corner located between the first wall portion 11 and the second wall portion 12, and is located on a diagonal line of position P1 in a vertical cross-sectional view. Fig. 5 shows a graph in which the horizontal axis represents the position in the thickness direction of the base 10 (positions P3 to P4) and the vertical axis represents the boron content.

[0042] As shown in Fig. 5, a first inner / outer difference G1 is a difference between the third boron content at the first corner of the first boron-containing layer 21 and the fourth boron content at the second corner of the second boron-containing layer 22. As shown in Fig. 4, a second inner / outer difference G2 is a difference between the first boron content in the first boron-containing layer 21 other than the first corner and the second boron content in the second boron-containing layer 22 other than the second corner. In this case, the first inner / outer difference G1 may be larger than the second inner / outer difference G2.

[0043] As described above, cracks may occur in the ceramic member 1 due to the temperature difference between the surface and the inside caused by heating or cooling. The corners of the base 10 are particularly prone to concentration of large thermal shocks. If the first inner / outer difference G1 is greater than the second inner / outer difference G2, the occurrence of cracks or breakage in the corners of the base 10 can be suitably reduced. In other words, with such a configuration, the thermal expansion difference at the corners is smaller, and therefore the occurrence of cracks or breakage in the corners can be suitably reduced.

[0044] 5, the difference between the maximum value of the boron content in the first boron-containing layer 21 (C10) and the maximum value of the boron content in the second boron-containing layer 22 (C8) is taken as the first inner / outer difference G1, but it is not limited thereto, and the first inner / outer difference G1 may be the difference between the average value of the boron content in the first boron-containing layer 21 and the average value of the boron content in the second boron-containing layer 22. Similarly, in FIG. 4, the difference between the maximum value of the boron content in the first boron-containing layer 21 (C5) and the maximum value of the boron content in the second boron-containing layer 22 (C3) is taken as the second inner / outer difference G2, but it is not limited thereto, and the second inner / outer difference G2 may be the difference between the average value of the boron content in the first boron-containing layer 21 and the average value of the boron content in the second boron-containing layer 22.

[0045] FIG. 6 is a graph showing another example of the change in boron content between positions P1 and P2 shown in FIG.

[0046] In the embodiment shown in Fig. 4, an example has been described in which the boron content on the inner wall surface side is greater than the boron content on the outer wall surface side. However, the present invention is not limited to this, and the boron content on the inner wall surface side of the base 10 may be less than the boron content on the outer wall surface side, as shown in Fig. 6. Even in this case, the ceramic member 1 according to the embodiment can have increased strength and thermal shock resistance, as described above.

[0047] 6, the boron content in the inner portion 22b of the second boron-containing layer 22 may be higher than the boron content in the surface portion 22a of the second boron-containing layer 22. With this configuration, even when the ceramic member 1 is rapidly cooled from the outer wall surface side, the thermal contraction of the outer wall surface side is reduced, and therefore cracks are less likely to occur starting from the outer wall surface side.

[0048] Fig. 7 is a schematic vertical cross-sectional view showing another example of the ceramic member according to the embodiment, and Fig. 8 is a graph showing the change in boron content between positions P5 and P6 shown in Fig. 7.

[0049] 7, the base 10 may have only the first boron-containing layer 21 out of the above-mentioned first boron-containing layer 21 and second boron-containing layer 22. In other words, the base 10 does not need to have the second boron-containing layer 22.

[0050] 8, the boron content of the base 10 is highest in the inner wall surface side R1, followed by the inside R2, and lowest in the outer wall surface side R3. In this case, the minimum value of the boron content of the outer wall surface side R3 (the boron content at least in the outermost surface on the outer wall surface side) may be 0.

[0051] Fig. 9 is a schematic vertical cross-sectional view showing another example of the ceramic member 1 according to the embodiment, and Fig. 10 is a graph showing the change in boron content between position P7 and position P8 shown in Fig. 9.

[0052] 9, the base 10 may have only the second boron-containing layer 22 out of the first boron-containing layer 21 and the second boron-containing layer 22. In other words, the base 10 does not need to have the first boron-containing layer 21.

[0053] 10, the boron content of the substrate 10 is highest in the outer wall surface side portion R3, followed by the interior portion R2, and lowest in the inner wall surface side portion R1. In this case, the minimum value of the boron content of the inner wall surface side portion R1 (the boron content at least in the outermost surface on the outer wall surface side) may be 0.

[0054] In the above-described embodiment, an example has been described in which the base 10 has a container shape, but the shape of the base 10 does not necessarily have to be a container shape. Fig. 11 and Fig. 12 are schematic vertical cross-sectional views of a ceramic member 1 according to another embodiment.

[0055] For example, as shown in Fig. 11, the shape of the substrate 10 may be plate-like. When the substrate 10 is plate-like, the ceramic member 1 may be used for, for example, a cooling bed for steel, a breaking blade attached to a cooling bed for steel, a partition wall for blocking high heat in a molten metal furnace or a blast furnace, a cover for a molten metal furnace, a fireproof plate or a partition wall for a flame in an incinerator, etc. The plate-like substrate 10 may have, for example, through holes, concave portions, convex portions, etc.

[0056] In the ceramic member 1 shown in FIG. 11, the first boron content in the first surface 11a may be greater than the second boron content in the second surface 11b.

[0057] In the ceramic member 1 shown in FIG. 11, the boron content inside the base 10 may be lower than the boron content in the first surface 11a and the boron content in the second surface 11b.

[0058] FIG. 11 shows an example in which the ceramic member 1 has the boron-containing layer 20 on both the first surface 11a and the second surface 11b of the base 10. However, the ceramic member 1 may have the boron-containing layer 20 on only one of the first surface 11a and the second surface 11b.

[0059] As shown in Fig. 12, the base 10 may have a cylindrical shape. When the base 10 has a cylindrical shape, the ceramic member 1 may be used, for example, as a thermocouple protection tube, a kiln furnace body, a runner for molten metal, a nozzle for molten metal, a stalk for molten metal, and a corrosion-resistant waste heat pipe in which metal materials cannot be used. In the example shown in Fig. 12, a cylindrical shape with both ends open is shown, but the base 10 may have a so-called bottomed cylindrical shape with one end closed. The base 10 may also have, for example, a through hole, a recess, a protrusion, or the like.

[0060] In the ceramic member 1 shown in FIG. 12, the second boron-containing layer 22 which is the outer wall surface may have a higher boron content than the first boron-containing layer 21 which is the inner wall surface.

[0061] For example, assume that the ceramic member 1 shown in FIG. 12 is heated from the outer wall surface side, that is, the temperature of the outer wall surface side becomes higher than that of the inner wall surface side.

[0062] When the boron content of the outer wall surface side is greater than that of the inner wall surface side, the thermal expansion coefficient of the outer wall surface side is smaller than that of the inner wall surface side. Although the outer wall surface side thermally expands more than the inner wall surface side, the difference in thermal expansion between the outer wall surface side and the inner wall surface side is small because the thermal expansion coefficient of the outer wall surface side is relatively small. This improves the thermal shock resistance of the ceramic member 1 and makes it less susceptible to cracks and breakage.

[0063] In addition, the outer wall surface side, which has a relatively high boron content, is less likely to shrink during firing than the inner wall surface side. On the other hand, the inner wall surface side, which has a relatively low boron content, is more likely to shrink during firing than the outer wall surface side. Due to these shrinkage differences, compressive stress remains on the outer wall surface side of the ceramic member 1 after firing. In this way, the ceramic member 1 has compressive stress remaining on the outer wall surface side, which improves the mechanical strength of the heat-resistant member 1 and improves its thermal shock resistance.

[0064] In the ceramic member 1 shown in FIG. 12, the boron content of the second boron-containing layer 22 which is the outer wall surface may be lower than the boron content of the first boron-containing layer 21 which is the inner wall surface.

[0065] For example, assume that the ceramic member 1 shown in FIG. 12 is heated from the inner wall surface side, that is, the temperature of the inner wall surface side becomes higher than that of the outer wall surface side.

[0066] When the boron content on the inner wall surface side is higher than the boron content on the outer wall surface side, it is suitable for applications such as placing a high-temperature object inside.

[0067] In the ceramic member 1 shown in FIG. 12, the boron content inside the base 10 may be lower than the boron content on the inner wall surface side and the outer wall surface side of the base 10. EXAMPLES

[0068] (Manufacturing method) Next, an example of a method for manufacturing the container-shaped ceramic member 1 will be described.

[0069] First, prepare multiple solutions with different boric acid concentrations. For example, water or an organic solvent (such as dimethyl sulfoxide) is used as the solvent for the solution. If the viscosity of the solution is low, an organic compound with a thickening effect, such as polyethylene glycol, may be added to make the solution into a paste.

[0070] Alumina granules containing an organic binder are prepared by a known method. The alumina granules contain known sintering aids such as MgO, SiO2, and CaO. However, the granules do not contain boric acid.

[0071] Next, alumina granules not containing boric acid (but containing a sintering aid) are used to produce a green body made of alumina in the shape of a container by a known molding method such as press molding using a die.

[0072] Next, boric acid solutions of different concentrations are applied to the inner wall surface side and the outer wall surface side of the raw formed body. For example, spraying with a spray can be used as the application method. The boric acid solution may be applied to only one of the inner wall surface side or the outer wall surface side.

[0073] By applying the boric acid solution to the raw body, the solution penetrates from the surface of the raw body into the inside of the raw body. As a result, the concentration of boric acid on the side where the boric acid was applied becomes higher than the concentration of boric acid inside the raw body. The raw body is then dried.

[0074] When the boric acid solution is applied only to one of the inner wall surface side or the outer wall surface side, the boron content of either the inner wall surface side or the outer wall surface side becomes zero.

[0075] Thereafter, the raw body is degreased and sintered at a temperature of 1200° C. to 1400° C. This produces a dense alumina sintered body in the shape of a container.

[0076] The shape and dimensions of the resulting dense alumina sintered body are as follows: Shape: Rectangular prism with an opening on one side Side wall dimensions (outer dimensions): 27mm x 44mm Bottom wall dimensions (external dimensions): 27mm x 44mm Side wall height (from bottom to opening): 44mm Wall thickness: 3mm

[0077] 13 is a table showing the test results of thermal shock resistance for lots L11 to L16. Lot L11 is a lot to which the boric acid solution was not applied, and corresponds to a comparative example. Lots L12 to L16 are lots to which the boric acid solution was applied, and correspond to examples.

[0078] The manufacturing method of lot L11 is the same as the manufacturing method of the dense alumina sintered base having the container shape described above, except that the application of the boric acid solution is omitted. As shown in Fig. 13, the number of applications of the boric acid solution on both the inner and outer wall sides of lot L11 is 0, and the average boron content is 0 mass%.

[0079] The manufacturing method of lots L12 to L16 was the same as the manufacturing method of the container-shaped dense alumina sintered base described above, except that the concentration of the boric acid solution to be applied and the number of times the boric acid solution was applied differed among lots L12 to L16.

[0080] Specifically, in lot L12, the concentration of the applied boric acid solution is 4g / 100mL on the inner wall side and 1g / 100mL on the outer wall side, and the number of applications is four on both the inner wall side and the outer wall side. In lot L13, the concentration of the applied boric acid solution is 8g / 100mL on the inner wall side and 2g / 100mL on the outer wall side, and the number of applications is three on both the inner wall side and the outer wall side. In lot L14, the concentration of the applied boric acid solution is 8g / 100mL on the inner wall side and 2g / 100mL on the outer wall side, and the number of applications is three on both the inner wall side and the outer wall side. In lot L15, the concentration of the applied boric acid solution is 11g / 100mL on the inner wall side and 3g / 100mL on the outer wall side, and the number of applications is three on both the inner wall side and the outer wall side. In lot L16, the concentration of the applied boric acid solution was 11 g / 100 mL on the inner wall side and 3 g / 100 mL on the outer wall side, and the application was performed four times on both the inner wall side and the outer wall side.

[0081] The average boron content of lots L12 to L16 was 0.47 mass% for lot L12, 0.65 mass% for lot L13, 0.79 mass% for lot L14, 1.06 mass% for lot L15, and 1.16 mass% for lot L16. The bulk density of lots L12 to L16 was 3.2 g / cm3 That was all.

[0082] (About thermal shock resistance test) The sample shape was a sintered body of 3 mm × 4 mm × 50 mm. The sintered body was unpolished, and the sample after sintering was used as it was in the test.

[0083] The sample is heated and held at a constant temperature (let's call it T2 (℃)) for 10 minutes. While held at T2 (℃), the sample is dropped into water at T1 = 25℃. When dropped into water, the sample is subjected to thermal shock. The sample dropped into water is retrieved, dried, and the three-point bending strength is measured. The method for measuring the three-point bending strength is the same as that for the three-point bending strength at room temperature (25℃) in accordance with JIS R1601-2008, except that the sample is a sintered body of 3mm x 4mm x 50mm (unpolished, and the sample after sintering is used as is in the test). T2 (℃) is raised, and the temperature difference (T2-T1 (℃)) just before the three-point bending strength begins to drop sharply is taken as the temperature at which the sample has thermal shock resistance.

[0084] As shown in FIG. 13, the results of the thermal shock resistance test (thermal shock resistance temperature) were 201°C for lot L11, 208°C for lot L12, 227°C for lot L13, 241°C for lot L14, 260°C for lot L15, and 287°C for lot L16.

[0085] Thus, the thermal shock resistance temperatures of all of the lots L12 to L16 containing boron were higher than that of the lot L11 not containing boron. This result shows that ceramic members containing boron have higher thermal shock resistance than ceramic members not containing boron. Furthermore, as is clear from the test results of the lots L12 to L16, the thermal shock resistance improves as the average boron content increases.

[0086] Fig. 14 is a graph showing the change in boron content in the thickness direction of the side wall of lot L14. Fig. 15 is a graph showing the change in boron content in the thickness direction of the bottom wall of lot L14. Fig. 16 is a graph showing the change in boron content in the thickness direction of the corner of lot L14. In the graphs shown in Figs. 14 to 16, the horizontal axis represents the distance from the inner wall surface side to the outer wall surface side, and the vertical axis represents the boron content calculated as B2O3.

[0087] As shown in Figures 14 to 16, a difference in boron content occurred between the inner wall surface and the outer wall surface in each of the side wall (first wall portion), bottom wall (second wall portion), and corners. Specifically, the boron content on the inner wall surface side to which a relatively high concentration boric acid solution was applied was higher than the boron content on the outer wall surface side to which a relatively low concentration boric acid solution was applied. In addition, the boron content inside was lower than the boron content on the inner wall surface side and the outer wall surface side. In addition, the difference between the inside and outside of the boron content in the corners (see Figure 16) was larger than the difference between the inside and outside of the boron content in the areas other than the corners (see Figures 14 and 15).

[0088] (Preliminary experiment) As a preliminary experiment, dense alumina crystals containing boron were manufactured by mixing the raw powder with boric acid powder, rather than by applying a boric acid solution to the raw material.The manufactured samples were then subjected to a thermal shock resistance test.

[0089] The manufacturing method of the sample in the preliminary experiment is as follows. Al2O3 powder is mixed with SiO2 powder, MgO powder, CaCO3 powder, and B2O3 powder as known sintering aids. The mixed powder is then crushed, granulated, and molded into a container shape, and then fired at 1350℃ for 2 hours. This results in a dense alumina crystal.

[0090] The shape and dimensions of the resulting dense alumina crystals are as follows: Shape: Rectangular prism with an opening on one side Side wall dimensions (outer dimensions): 27mm x 44mm Bottom wall dimensions (external dimensions): 27mm x 44mm Side wall height (from bottom to opening): 44mm Wall thickness: 3mm

[0091] Fig. 17 is a table summarizing the test results in the preliminary experiment. Fig. 18 is a graph showing the test results of the three-point bending strength in the preliminary experiment. Fig. 19 is a graph showing the test results of the average thermal expansion coefficient in the preliminary experiment. Fig. 20 is a graph showing the test results of the thermal shock resistance in the preliminary experiment.

[0092] As shown in Fig. 17, four lots, L21 to L24, were prepared in the preliminary experiment. Lot L21 had an Al content of 74 mass% in Al2O3 conversion, an Si content of 18.4 mass% in SiO2 conversion, an Mg content of 2.5 mass% in MgO conversion, an Ca content of 5 mass% in CaO conversion, and an B content of 0.1 mass% in B2O3 conversion. Lot L22 had an Al content of 73.6 mass% in Al2O3 conversion, an Si content of 18.4 mass% in SiO2 conversion, an Mg content of 2.5 mass% in MgO conversion, an Ca content of 5 mass% in CaO conversion, and an B content of 0.5 mass% in B2O3 conversion. Lot L23 has an Al content of 73 mass% calculated as Al2O3, an Si content of 18.4 mass% calculated as SiO2, an Mg content of 2.5 mass% calculated as MgO, an Ca content of 5 mass% calculated as CaO, and an B content of 1.1 mass% calculated as B2O3. Lot L24 has an Al content of 72.1 mass% calculated as Al2O3, an Si content of 18.4 mass% calculated as SiO2, an Mg content of 2.5 mass% calculated as MgO, an Ca content of 5 mass% calculated as CaO, and an B content of 2.0 mass% calculated as B2O3.

[0093] For these lots L21 to L24, measurements were made of the bulk density, Young's modulus, three-point bending strength, average thermal expansion coefficient at 25° C. or more and 400° C. or less, and thermal shock resistance temperature. The results are as follows.

[0094] <Lot L21> Bulk density: 3.3g / cm3 Young's modulus: 205GPa 3-point bending strength: 219MPa Average thermal expansion coefficient: 6.4 x 10 -6 / ℃ Thermal shock resistance temperature: 195℃

[0095] <Lot L22> Bulk density: 3.3g / cm 3 Young's modulus: 207GPa 3-point bending strength: 293MPa Average thermal expansion coefficient: 6.1 x 10 -6 / ℃ Thermal shock resistance temperature: 241℃

[0096] <Lot L23> Bulk density: 3.3g / cm 3 Young's modulus: 199GPa 3-point bending strength: 337MPa Average thermal expansion coefficient: 5.8 x 10 -6 / ℃ Thermal shock resistance temperature: 273℃

[0097] <Lot L24> Bulk density: 3.3g / cm 3 Young's modulus: 190GPa 3-point bending strength: 360MPa Average thermal expansion coefficient: 5.6 x 10 -6 / ℃ Thermal shock resistance temperature: 290℃

[0098] As is clear from the above results, as the boron content in B2O3 conversion increases, the three-point bending strength increases (see FIG. 18), the thermal expansion coefficient decreases (see FIG. 19), and the thermal shock resistance temperature increases (see FIG. 20). In addition, for all of lots L21 to L24, the bulk density was 3.2 g / cm 3 That is, it is found that all of lots L21 to L24 are dense bodies.

[0099] As described above, the ceramic member according to the embodiment (for example, the ceramic member 1) has a base (for example, the base 10) made of ceramic. The base has a boron-containing layer, for example, the boron-containing layer 20, on at least the first surface 11a or the second surface 11b (for example, the outer wall surface or the inner wall surface).

[0100] Therefore, according to the embodiment, it is possible to provide a ceramic member having excellent thermal shock resistance, and the ceramic member can be suitably used, in particular, as a heat-resistant member.

[0101] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0102] 1 Ceramic components 10 Base 11 First wall 11a 1st surface, inner wall surface 11b 2nd side, outer wall surface 11c Third side, top side 12 Second wall 13 Opening 14 First corner, inner wall side corner 15 2nd corner, outer wall side corner 20 Boron-containing layer 21 First boron-containing layer 21a Surface layer 21b internal 22 Second boron-containing layer 22a Surface layer 22b internal R1 Inner wall side R2 Area between the inner wall side and the outer wall side R3 Exterior wall side

Claims

1. The present invention has a substrate made of a ceramic containing boron, a boron-containing layer on a surface of the substrate, the boron-containing layer containing more boron than the boron content in the interior of the substrate; The substrate is The first page and a second surface located opposite the first surface, the first face having a first boron-containing layer at a first surface portion; the second face having a second boron-containing layer at a second surface portion; the boron content of the first boron-containing layer is a first boron content; When the boron content of the second boron-containing layer is defined as a second boron content, the first boron content and the second boron content are different; the substrate is in the form of a container having a wall; the first surface is an inner wall surface of the container, the second surface is an outer wall surface of the container, the first boron content is greater than the second boron content; Ceramic components.

2. A ceramic substrate comprising: a boron-containing layer on a surface of the substrate, the boron-containing layer containing more boron than the boron content in the interior of the substrate; The substrate is The first page and a second surface located opposite the first surface, the first face having a first boron-containing layer at a first surface portion; the second face having a second boron-containing layer at a second surface portion; the boron content of the first boron-containing layer is a first boron content; When the boron content of the second boron-containing layer is defined as a second boron content, the first boron content and the second boron content are different; the substrate is in the form of a container having a wall; the first surface is an inner wall surface of the container, the second surface is an outer wall surface of the container, The ceramic member, wherein the first boron content is less than the second boron content.

3. The substrate is The wall portion includes a plurality of the walls. A corner portion located between adjacent walls on an inner wall surface of the wall portion is defined as a first corner portion, a boron content in a surface portion of the first corner portion is defined as a third boron content; A corner portion located between adjacent wall portions on an outer wall surface of the wall portion is defined as a second corner portion, the boron content in the surface portion of the second corner portion is defined as a fourth boron content; a difference between the third boron content and the fourth boron content is a first inner / outer difference; the first boron content in a region other than the first corner portion; and When the difference between the second boron content in the region other than the second corner portion and the second boron content in the region other than the second corner portion is defined as a second inside-outside difference, The ceramic member according to claim 1 or 2, wherein the first inner / outer difference is greater than the second inner / outer difference.

4. 3. The ceramic member according to claim 1, wherein the substrate is made of an aluminum oxide ceramic having a polycrystalline structure with a porosity of 5% or less.

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