Ceramic structure

Abstract

This ceramic structure is provided with a base, a first layer, and a second layer. The base is made of a ceramic. The first layer is located in contact with the surface of the base and is made of a ceramic having a different composition to that of the base. The second layer is located in contact with the surface of the first layer and is made of a metal. In a cross-section intersecting the surface of the base, when the average grain diameter of main crystals of the base is represented by DB, the respective measurement values when the thickness of the first layer is measured at 1-μm intervals are represented by D1 to Dn, and the average value of D1 to Dn is represented by DAVE, the first layer has concavo-convex features in which |Dn-DAVE| is greater than DB / 2.

Description

Technical Field

[0001] The disclosed embodiments relate to a ceramic structure.

Background Art

[0002] Ceramics are widely used in structures from the viewpoints of strength, insulation, heat resistance, etc. Also, as this ceramic structure, a structure in which a metallized layer is provided on the surface of a substrate made of ceramics is known. For example, refer to Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The ceramic structure of the present disclosure includes a substrate, a first layer, and a second layer. The substrate is made of ceramics. The first layer is located in contact with the surface of the substrate and is made of ceramics having a composition different from that of the substrate. The second layer is located in contact with the surface of the first layer and is made of metal. Also, in a cross section intersecting the surface of the substrate, the average grain size of the main crystal of the substrate is D ,

[0005] , , B , [Figure 2] , [Figure 1] , , , Let it be, and when the thickness of the first layer is measured at intervals of 1 μm, let the respective measured values be D1 to D n Let it be, and the average value of the D1 to D n Let it be D AVE In this case, the first layer has irregularities where |D n -D AVE | is greater than D B / 2.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of the ceramic structure according to the embodiment. [Figure 2]Figure 2 is an enlarged cross-sectional view showing an example of the configuration of a ceramic structure according to the embodiment. [Figure 3] Figure 3 shows an SEM image of the substrate surface of the ceramic structure of Example 1. [Figure 4] Figure 4 shows an SEM image of the substrate surface of the ceramic structure in Reference Example 1. [Figure 5] Figure 5 shows a cross-sectional SEM image of the ceramic structure near the surface of Example 1. [Figure 6] Figure 6 shows the Al distribution in a cross-sectional view near the surface of the ceramic structure of Example 1. [Figure 7] Figure 7 shows the Mn distribution in a cross-sectional view near the surface of the ceramic structure of Example 1. [Figure 8] Figure 8 shows the Mg distribution in a cross-sectional view near the surface of the ceramic structure of Example 1. [Figure 9] Figure 9 shows a cross-sectional SEM image of the ceramic structure near the surface of Reference Example 1. [Figure 10] Figure 10 shows the Al distribution in a cross-sectional view near the surface of the ceramic structure of Reference Example 1. [Figure 11] Figure 11 shows the Mn distribution in a cross-sectional view near the surface of the ceramic structure in Reference Example 1. [Figure 12] Figure 12 shows the Mg distribution in a cross-sectional view near the surface of the ceramic structure in Reference Example 1. [Modes for carrying out the invention]

[0006] The embodiments of the ceramic structure disclosed herein will be described below with reference to the attached drawings. However, the embodiments described below do not limit this disclosure. Furthermore, each embodiment can be combined as appropriate, provided that the processing details are not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the embodiments below, and redundant descriptions are omitted.

[0007] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations, for example, in manufacturing accuracy or installation accuracy.

[0008] Ceramics are widely used in structures due to their strength, insulation properties, and heat resistance. Furthermore, a known type of ceramic structure consists of a ceramic substrate with a metallized layer on its surface.

[0009] However, conventional technologies still had room for improvement in terms of enhancing the adhesion between the ceramic substrate and the metallized layer. Therefore, there is a need for a technology that can overcome the aforementioned problems and improve the adhesion between the ceramic substrate and the metallized layer in ceramic structures.

[0010] Figure 1 is a schematic perspective view of the ceramic structure 1 according to the embodiment, and Figure 2 is an enlarged cross-sectional view showing an example of the configuration of the ceramic structure 1 according to the embodiment. Note that Figure 2 is a cross-sectional view taken along the line AA shown in Figure 1.

[0011] As shown in Figures 1 and 2, the ceramic structure 1 according to the embodiment comprises a substrate 2, a first layer 3, and a second layer 4. The substrate 2 is, for example, rectangular parallelepiped and has a surface 2a. In this disclosure, the shape of the substrate 2 is as shown in Figure 1. 1 The examples are not limited to those shown, and any shape is acceptable, such as plate-shaped, frame-shaped, or columnar.

[0012] The substrate 2 is composed of a sintered ceramic body. Examples of ceramics that make up the substrate 2 include those mainly composed of aluminum oxide (Al2O3), silicon carbide (SiC), silicon carbonitride (SiCN), titanium carbide (TiC), and titanium carbonitride (TiCN).

[0013] In this disclosure, "main component" refers to a component that accounts for 80% or more of the total 100% by mass of the components constituting the ceramics. The identification of each component contained in the ceramics is performed using an X-ray diffractometer that uses CuKα rays, and the content of each component can be determined, for example, by an ICP (Inductively Coupled Plasma) emission spectrometer or an X-ray fluorescence analyzer.

[0014] When the main component of substrate 2 is aluminum oxide, it is relatively inexpensive among ceramics, including raw material costs and manufacturing costs, while possessing excellent mechanical properties.

[0015] Furthermore, if the main component of base material 2 is aluminum oxide, base material 2 may further contain oxides of magnesium (Mg), calcium (Ca), and silicon (Si), for example.

[0016] As shown in Figure 2, the first layer 3 is located in contact with the surface 2a of the substrate 2. The first layer 3 is made of ceramics with a different composition from the substrate 2. The constituent elements of the first layer 3 may, for example, include one or more elements present in the substrate 2, as well as one or more elements present in the second layer 4.

[0017] The second layer 4 is located in contact with the surface 3a of the first layer 3. The second layer 4 is made of metal and is also called the metallized layer. The second layer 4 may be formed of a metallic material such as molybdenum (Mo), manganese (Mn), tungsten (W), copper (Cu), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), or an alloy of these metallic materials.

[0018] The second layer 4 may contain, for example, molybdenum and manganese. This allows for the formation of a second layer 4, which is a metal layer with good adhesion to the ceramic substrate 2.

[0019] The second layer 4 can be formed, for example, by applying a metal paste prepared by kneading the above-mentioned metal material powder together with an organic solvent, a binder, etc. onto a ceramic green sheet serving as the substrate 2 and co-firing in a reducing atmosphere. At this time, a first layer 3, which is an intermediate layer, is formed at the interface between the substrate 2 and the second layer 4.

[0020] In the examples of FIGS. 1 and 2, an example where the second layer 4 is exposed is shown. However, the present disclosure is not limited to such an example, and another layer such as nickel (Ni) plating may be provided on the surface of the second layer 4.

[0021] Here, in the embodiment, in a cross-section intersecting with the surface 2a of the substrate 2, that is, in the cross-section shown in FIG. 2, the average grain size of the main crystal (not shown) of the substrate 2 is D B Let the respective measured values when the thickness of the first layer 3 is measured at 1-μm intervals be D1 to D n Let the average value of such D1 to D n be D AVE In D n n is an integer. The main crystal refers to a crystal that occupies 50 area% or more in the substrate.

[0022] And in the embodiment, the first layer 3 has irregularities where |D n -D AVE | is larger than D B / 2. Thus, by the first layer 3 having irregularities larger than the value based on the grain size of the main crystal of the substrate 2, the anchor effect of the first layer 3 on the surface 2a of the substrate 2 can be enhanced.

[0023] Therefore, according to the embodiment, the adhesion of the first layer 3 to the substrate 2 can be enhanced, so that the adhesion between the substrate 2 and the second layer 4 can be improved. Also, the adhesion is particularly high when the minimum width at which the substrate 2 and the first layer 3 contact is 1 mm or more. From the viewpoint of adhesion, the minimum width may be 2 mm or more, and further 3 mm or more.

[0024] Furthermore, in this embodiment, the main crystal of the substrate 2 may be aluminum oxide. That is, the substrate 2 may be mainly composed of aluminum oxide. This allows the ceramic structure 1 to have excellent mechanical properties while being relatively inexpensive, including raw material costs and manufacturing costs.

[0025] Furthermore, in this embodiment, the constituent elements of the first layer 3 may include one or more elements present in the substrate 2, as well as one or more elements present in the second layer 4. For example, if the substrate 2 contains Al, Mg, Ca, Si, and oxygen (O), and the second layer 4 contains Mo and Mn, the first layer 3 may contain Mg, Al, Mn, and O.

[0026] In this way, by having the intermediate layer, the first layer 3, contain all the elements found in the substrate 2 and the second layer 4, the adhesion between the substrate 2 and the first layer 3, and the adhesion between the first layer 3 and the second layer 4 can be improved.

[0027] Therefore, according to this embodiment, the adhesion between the substrate 2 and the second layer 4 can be further improved.

[0028] In addition, in the embodiment, the first layer 3 may have a crystal having a spinel-type crystal structure. For example, if the substrate 2 contains Al, Mg, Ca, Si, and O, and the second layer 4 contains Mo and Mn, the first layer 3 may contain at least one of MgO·Al2O3 spinel crystals and MnO·Al2O3 spinel crystals.

[0029] This makes it possible to bring the thermal expansion coefficient of the substrate 2, which is mainly composed of aluminum oxide, closer to that of the first layer 3, which contains the spinel crystals mentioned above. Therefore, according to this embodiment, delamination between the substrate 2 and the second layer 4 caused by thermal cycling can be reduced.

[0030] Furthermore, in this embodiment, as shown in Figure 1, the thickness t of the substrate 2 when the second layer 4 is placed on the upper surface may be 2.0 mm or more. This makes it possible to realize a ceramic structure 1 with high insulating properties for the second layer 4, which is the metallization layer. [Examples]

[0031] The following describes specific examples of the present disclosure. While the following examples show a substrate 2 having aluminum oxide as the main crystal, the present disclosure is not limited to these examples.

[0032] <Examples 1-3> First, powder of aluminum oxide, the main component of substrate 2, and powders of silicon oxide (SiO2), magnesium oxide (MgO), and calcium oxide (CaO), which are sintering aids, were prepared. Then, the aluminum oxide powder and the sintering aid powders were mixed so that the composition was Al2O3:90% by mass, SiO2:7% by mass, MgO:2% by mass, and CaO:1% by mass. Water and a dispersant were added, and the mixture was mixed for a predetermined time using a ball mill or bead mill to obtain a primary slurry.

[0033] Next, an organic binder was added to the obtained primary slurry and mixed to form a secondary slurry. Then, the obtained secondary slurry was spray-dried to obtain granules whose main component was aluminum oxide.

[0034] Next, the obtained granules were filled into a predetermined mold and press-molded into a predetermined shape, such as a rectangular parallelepiped, at an appropriately set pressure to obtain a generated form that would become the base body 2.

[0035] In parallel with the preparation process for the substrate 2, a metal paste for the second layer 4 was prepared. Specifically, molybdenum and manganese powders, which constitute the second layer 4, and titanium oxide (TiO2) powder, which is a sintering aid, were prepared first.

[0036] Then, molybdenum and manganese powders and sintering aid powders were mixed in the following proportions: Mo: 85% by mass, Mn: 10% by mass, and TiO2: 5% by mass. An organic binder was then added and mixed to obtain a metal paste.

[0037] Next, a metal paste was printed onto the surface of the generated shape by screen printing, and the sample was fired in a reducing atmosphere, for example, a 20% hydrogen + 80% nitrogen atmosphere, for a predetermined time to obtain three samples, which will be Examples 1 to 3. The sintering temperature during this firing process was, for example, 1420°C.

[0038] <Reference examples 1~3> First, powder of aluminum oxide, the main component of substrate 2, and powders of silicon oxide (SiO2), magnesium oxide (MgO), and calcium oxide (CaO), which are sintering aids, were prepared. Then, the aluminum oxide powder and the sintering aid powders were mixed so that the composition was Al2O3:90% by mass, SiO2:7% by mass, MgO:2% by mass, and CaO:1% by mass. Water and a dispersant were added, and the mixture was mixed for a predetermined time using a ball mill or bead mill to obtain a primary slurry.

[0039] Next, an organic binder was added to the obtained primary slurry and mixed to form a secondary slurry. Then, the obtained secondary slurry was spray-dried to obtain granules whose main component was aluminum oxide.

[0040] Next, the obtained granules were filled into a predetermined mold and press-molded into a predetermined shape, for example, a rectangular parallelepiped, at an appropriately set pressure. raw The molded body was subjected to primary firing in air to obtain a primary fired body that would become the base body 2. The sintering temperature during this primary firing process was, for example, 1420°C.

[0041] In parallel with the preparation process for the primary sintered body that will become the base body 2, a metal paste that will become the second layer 4 was prepared. Specifically, first, molybdenum and manganese powders that will make up the second layer 4, and titanium oxide (TiO2) powder, which will be used as a sintering aid, were prepared.

[0042] Then, molybdenum and manganese powders and sintering aid powders were mixed in the following proportions: Mo: 85% by mass, Mn: 10% by mass, and TiO2: 5% by mass. An organic binder was then added and mixed to obtain a metal paste.

[0043] Next, a metal paste was printed onto the surface of the primary fired body by screen printing, and the body was subjected to secondary firing in a reducing atmosphere, for example, an atmosphere of 20% hydrogen and 80% nitrogen, for a predetermined time to obtain three samples, which will be referred to as Reference Examples 1 to 3. The sintering temperature during this secondary firing process was, for example, 1350°C.

[0044] <Various evaluations> Next, the surfaces of the substrate 2 exposed on the sides, etc., of the ceramic structures 1 of Examples 1 to 3 and Reference Examples 1 to 3 obtained above were observed using a scanning electron microscope (SEM). Figure 3 shows an SEM image of the substrate surface of the ceramic structure 1 of Example 1, and Figure 4 shows an SEM image of the substrate surface of the ceramic structure 1 of Reference Example 1.

[0045] Then, using the obtained SEM observation images, the average particle size D of aluminum oxide, which is the main crystal of substrate 2 in Examples 1-3 and Reference Examples 1-3, was determined. B The particles were measured using the coding method. Specifically, first, lines were drawn to divide the vertical and horizontal directions of the SEM image to be measured into five or more equal parts. Then, the number of particles touching each line was counted.

[0046] Next, the particle size is calculated from the counted number of particles and the scale of the line. Finally, the average value of all the calculated particle sizes is used to determine the average particle size D of the main crystal. B This was the result. Particles whose entire form was not visible in the photograph were excluded from the measurement.

[0047] Furthermore, in the ceramic structures 1 of Examples 1-3 and Reference Examples 1-3 obtained above, the adhesive strength of the second layer 4 to the substrate 2 was measured using the peel strength measurement method. First, a sample for measurement was prepared. Specifically, nickel plating was formed on the surface of the second layer 4, and Kovar was brazed onto the nickel-plated surface with Ag brazing material.

[0048] Next, the brazed sample was placed in a jig, and the jig was chucked to one end of the Kovar lead. Then, the second layer 4 was peeled off from one end, and the adhesive strength was measured at five points at 1 mm intervals from an arbitrary distance during the peeling process, and the values ​​were read. The adhesive strength was measured under conditions of a load cell of 98 N and a crosshead speed of 10 mm / min.

[0049] The measured values ​​were then averaged over five points to determine the adhesive strength per measurement. This measurement was repeated 5 to 10 times, and the average adhesive strength was used as the adhesive strength of the sample. The unit of adhesive strength is Newtons (N).

[0050] Furthermore, the ceramic structures 1 of Examples 1-3 and Reference Examples 1-3 obtained above were cut, and the cut surfaces were mirror-polished. The cross-sections of the substrate 2, first layer 3, and second layer 4 were then observed using a scanning electron microscope (SEM). In addition, elemental mapping of various elements was performed on the field of view observed by the SEM using an Electron Probe Microanalyzer (EPMA).

[0051] Figure 5 shows a cross-sectional SEM image of the ceramic structure 1 of Example 1 near its surface. Figures 6 to 8 show the Al, Mn, and Mg distributions in a cross-sectional view near the surface of the ceramic structure 1 of Example 1.

[0052] Figure 9 shows a cross-sectional SEM image of the area near the surface of the ceramic structure 1 of Reference Example 1. Figures 10 to 12 show the Al, Mn, and Mg distributions in a cross-sectional view near the surface of the ceramic structure 1 of Reference Example 1.

[0053] As shown in Figures 6 to 8, in the ceramic structures 1 of Examples 1 to 3, it can be seen that a first layer 3, which is an intermediate layer containing Al and Mg contained in the substrate 2 and Mn contained in the second layer 4, is formed between the substrate 2 and the second layer 4.

[0054] Furthermore, as shown in Figures 6 to 8, it can be seen that the ceramic structures 1 of Examples 1 to 3 have a first layer 3, which is an intermediate layer with a larger film thickness, compared to the ceramic structures 1 of Reference Examples 1 to 3 shown in Figures 10 to 12.

[0055] Furthermore, as shown in Figures 6 to 8, the ceramic structures 1 of Examples 1 to 3 have an intricate shape, that is, a shape with large irregularities, in the first layer 3, which is the intermediate layer, compared to the ceramic structures 1 of Reference Examples 1 to 3.

[0056] It is presumed that this is because applying a metal paste to the surface of the generated form and firing the generated form and the metal paste simultaneously facilitates the movement of elements at the interface between the substrate 2 and the second layer 4, compared to applying a metal paste to the surface of the fired body and firing the metal paste separately.

[0057] Furthermore, for the ceramic structures 1 of Examples 1-3 and Reference Examples 1-3, the regions where these three elements are present are considered to be the first layer 3, using mapping images of the Al, Mn, and Mg distributions, and the thickness D1-D of the first layer 3 is determined. n The measurement was taken at 20 points with a 1 μm interval.

[0058] In this case, the Al, Mn, and Mg distribution mapping images used were color images obtained directly from the analyzer, rather than the grayscale images shown in Figures 6-8 and 10-12.

[0059] And the required thickness D1~D n Using this, the average value D of the thickness of the first layer 3 AVE Furthermore, determine the thickness D1 to D n and the average value D AVE The absolute value of the difference between |Dn -D AVE | was found.

[0060] Here, for Examples 1-3 and Reference Examples 1-3, the adhesive strength of the sample and the average grain size D of the main crystal are discussed. B And the thickness D of the 20 points in the first layer 3. n and |D n -D AVE | and, D n and |D n -D AVE The mean, maximum, minimum, and standard deviation σ of |, and |D n -D AVE | is the average particle size D B Table 1 shows the number of measurement points greater than / 2. Note that the results in Table 1 are obtained from the color images from the analyzer, showing the thickness D1~D n These are values ​​obtained by manual measurement. Also, in Table 1, |D n -D AVE | is the average particle size D B Measurement points with values ​​greater than / 2 are enclosed in a thick border.

[0061] [Table 1]

[0062] A comparison of Examples 1-3 with Reference Examples 1-3 shows that the adhesive strength of the second layer 4 to the substrate 2 is improved in Examples 1-3 compared to Reference Examples 1-3.

[0063] Furthermore, a comparison of Examples 1-3 and Reference Examples 1-3 shows that Examples 1-3 have a lower |D ratio compared to Reference Examples 1-3. n -D AVE | is D B The first layer 3 has a large number of irregularities greater than / 2.

[0064] In other words, in the embodiment, the first layer 3 is |D n -D AVE | is D BBecause it has many irregularities larger than / 2, the anchoring effect of the first layer 3 on the surface 2a of the base 2 can be enhanced, thereby improving the adhesion between the base 2 and the second layer 4, i.e., the adhesive strength.

[0065] Furthermore, by comparing Examples 1-3 with Reference Examples 1-3, |D n -D AVE | is D B Having three or more irregularities greater than / 2 further enhances the anchoring effect of the first layer 3 on the surface 2a of the base 2, thereby further improving the adhesion between the base 2 and the second layer 4, i.e., the adhesive strength.

[0066] Furthermore, for the ceramic structures 1 of Examples 1-3 and Reference Examples 1-3, the thickness D1-D of the first layer 3 was analyzed using the image analysis software Image Pro ver.10 from MEDIA CYBERNETICS. n The value was measured at 40 points at 1 μm intervals, and the minimum value y1 and maximum value y2 were also measured.

[0067] The minimum value y1 is the minimum coordinate position in the vertical direction in the SEM image at the interface between the substrate 2 and the first layer 3, in the stacking direction. The maximum value y2 is the maximum coordinate position in the stacking direction at the interface between the first layer 3 and the second layer 4.

[0068] In this case, a SEM image from a different field of view than the one used to obtain the measurement results shown in Table 1 was used. The specific procedure is as follows.

[0069] First, open the image to be analyzed. Next, perform calibration according to the image scale using "Create Calibration Data" on the "Home" tab. Depending on the interface conditions, you may use SEM images at scales of 1000 to 5000 times. In this case, we used an SEM image at a scale of 3000 times.

[0070] Next, use the "Measurement Shape - Automatic Trace of Free Curve" function in the "Measurement" tab to create the contour line of the boundary between the first layer 3 and the second layer 4. Also, use the "Measurement Shape - Automatic Trace of Free Curve" function in the "Measurement" tab to create the contour line of the boundary between the first layer 3 and the base 2.

[0071] Next, select the two created contour lines using the "Select" option in the "Measure" tab. Then, measure the two selected contour lines using the "Continuous Interval Measurement" option in the "Measure" tab. In this case, the interval for continuous interval measurement was set to 1 μm.

[0072] Next, add "Line Segment Length," "Start Point y of Line," and "End Point y of Line" to the measurement items under "Measurement Items" in the "Measurement" tab. Then, create a data collection table under "Collection" in the "Measurement" tab.

[0073] Finally, from the data recorded in the data collection table, the "mean value D AVE "D n "Maximum value", "D n The minimum value of "D n The standard deviation of the line was calculated. Furthermore, the minimum value of the starting point y of the line was defined as minimum value y1, and the maximum value of the ending point y of the line was defined as maximum value y2. The difference between this maximum value y2 and minimum value y1 was defined as difference D. R That is, D R = y² - y¹.

[0074] Here, for Examples 1-3 and Reference Examples 1-3, the adhesive strength of the sample and the thickness D are discussed. n The mean, maximum, minimum, and standard deviation σ, and the difference D R The results are shown in Table 2.

[0075] Furthermore, for Examples 1-3 and Reference Examples 1-3, the adhesive strength of the samples and the average grain size D of the main crystal, measured using the image analysis software Image Pro ver.10 from MEDIA CYBERNETICS, were also measured. B And the thickness D of the 40 points in the first layer 3. n and |D n -D AVE | and, D n and |Dn -D AVE The mean, maximum, minimum, and standard deviation σ of |, and |D n -D AVE | is the average particle size D B Table 3 shows the number of measurement points greater than / 2. Note that in Table 3, |D n -D AVE | is the average particle size D B Measurement points with values ​​greater than / 2 are enclosed in a thick border.

[0076] [Table 2]

[0077] [Table 3]

[0078] By comparing Examples 1-3 with Reference Examples 1-3, the difference D R A value of 4 μm or more enhances the anchoring effect of the first layer 3 on the surface 2a of the substrate 2, thereby improving the adhesion between the substrate 2 and the second layer 4, i.e., the adhesive strength.

[0079] Furthermore, by comparing Examples 1-3 with Reference Examples 1-3, the difference D R A value of 7 μm or more further enhances the anchoring effect of the first layer 3 on the surface 2a of the substrate 2, thereby further improving the adhesion between the substrate 2 and the second layer 4, i.e., the adhesive strength.

[0080] Furthermore, XRD (X-ray diffraction analysis) was performed on the mirror-polished cross-sections of the ceramic structures 1 obtained in Examples 1-3 and Reference Examples 1-3 to evaluate the crystalline state of the vicinity of the first layer 3 and the substrate 2.

[0081] This revealed that in Examples 1-3 and Reference Examples 1-3, the substrate 2 contained 97.8% by mass of aluminum oxide as the main phase and 2.2% by mass of sapphirin as the other phase.

[0082] Furthermore, in Examples 1 to 3, the vicinity of the first layer 3 contained 94.0% by mass of aluminum oxide and 6.0% by mass of spinel. On the other hand, in Reference Examples 1 to 3, the vicinity of the first layer 3 contained 98.3% by mass of aluminum oxide and 1.7% by mass of sapphirin.

[0083] In other words, in Examples 1 to 3, it was found that the first layer 3 has a crystal structure consisting of a spinel-type crystal structure. This makes it possible to reduce delamination between the substrate 2 and the second layer 4 caused by thermal expansion and contraction.

[0084] While embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from its spirit.

[0085] Further effects and other embodiments can be readily derived by those skilled in the art. Therefore, broader embodiments of this disclosure are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0086] 1. Ceramic structure 2 Base 2a surface 3 1st layer 3a surface 4 2nd layer

Claims

1. A substrate made of ceramics, A first layer is located in contact with the surface of the substrate and is made of ceramics having a different composition from the substrate. A second layer, made of metal, is located in contact with the surface of the first layer, Equipped with, In a cross-section that intersects the surface of the substrate, The interface between the substrate and the first layer and the interface between the first layer and the second layer each have a plurality of recesses and a plurality of protrusions. The average grain size of the main crystal of the substrate is D Ｂ year, When the thickness of the first layer is measured at 20 points at 1 μm intervals, each measurement value is D １ ~D ｎ year, The aforementioned D １ ~D ｎ The average value is D ＡＶＥ In that case, The first layer has |D ｎ -D ＡＶＥ | greater than D Ｂ / 2 and has a plurality of concavities and convexities Ceramic structure.

2. A substrate made of ceramics, A first layer is located in contact with the surface of the substrate and is made of ceramics having a different composition from the substrate. A second layer, made of metal, is located in contact with the surface of the first layer, Equipped with, In a cross-section that intersects the surface of the substrate, The interface between the substrate and the first layer and the interface between the first layer and the second layer each have a plurality of recesses and a plurality of protrusions. When the thickness of the first layer is measured at 40 points with 1 μm intervals: Let y1 be the minimum value of the coordinate position in the stacking direction at the interface between the substrate and the first layer. Let y2 be the maximum value of the coordinate position in the stacking direction at the interface between the first layer and the second layer. The difference between y2 and y1 is D Ｒ In that case, The aforementioned D Ｒ It is 4 μm or larger. Ceramic structure.

3. The aforementioned D Ｒ It is 7 μm or larger. The ceramic structure according to claim 2.

4. The average grain size of the main crystal of the substrate is D Ｂ year, When the thickness of the first layer is measured at 1 μm intervals, each measured value is D １ ~D ｎ year, The aforementioned D １ ~D ｎ The average value is D ＡＶＥ In that case, The first layer is |D ｎ -D ＡＶＥ | is D Ｂ Having a greater unevenness than / 2 The ceramic structure according to claim 2 or 3.

5. The number of bumps and ridges is three or more. The ceramic structure according to claim 1.

6. The main crystal of the substrate is aluminum oxide. A ceramic structure according to any one of claims 1 to 3.

7. The constituent elements of the first layer include one or more elements present in the substrate, and one or more elements present in the second layer. A ceramic structure according to any one of claims 1 to 3.

8. The first layer has a crystal having a spinel-type crystal structure. A ceramic structure according to any one of claims 1 to 3.

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