Sintered body having excellent impact resistance

Abstract

To provide at least one of: a sintered body that shows improved impact resistance by generating impact absorption by plastic deformation, against the impact exceeding the fracture resistance of the sintered body, prior to the occurrence of brittle fracture; and a method for producing the same.SOLUTION: A sintered body contains zirconia containing a stabilizer, and a pigment, and has a region in which an impact mark is formed when impact force is applied.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a sintered body having excellent impact resistance, and particularly to a sintered body mainly composed of zirconia and having excellent impact resistance.

Background Art

[0002] Compared with metal materials, ceramics have high mechanical properties and chemical stability, but are brittle materials. Therefore, when a dynamic impact at room temperature such as dropping is applied, a sintered body such as zirconia ceramics is likely to undergo so-called brittle fracture due to the generation and propagation of cracks. In order to prevent such fracture due to brittle fracture, improvement of fracture toughness has been studied.

[0003] For example, Patent Document 1 reports that the fracture toughness is improved by dispersing SrAl 12 O 19 in 4 mol% yttria-containing zirconia. Further, Patent Document 2 reports that the fracture toughness is improved and the drop resistance is improved by dispersing cubic Sr x NbO3 in zirconia.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The improvement in impact resistance in Patent Documents 1 and 2 was the result of the improvement in fracture resistance obtained by improving fracture toughness. For any of the sintered compacts, against an impact exceeding the fracture resistance, brittle fracture such as the generation of cracks occurred first, and fracture occurred as it progressed. Thus, the fracture mechanism in any of the sintered compacts was caused only by brittle fracture.

[0006] In contrast, in the present disclosure, an object is to provide at least one of a sintered compact with improved impact resistance and a method for manufacturing the same, by generating impact absorption by plastic deformation prior to the occurrence of brittle fracture against an impact exceeding the fracture resistance of the sintered compact.

Means for Solving the Problems

[0007] The inventors of the present invention studied the improvement of the impact resistance of ceramics. As a result, it was found that an improvement in impact resistance can be obtained by a mechanism different from the improvement in fracture toughness.

[0008] That is, the present invention is as described in the invention recited in the claims, and the gist of the present disclosure is as follows. [1] A sintered compact containing stabilized zirconia and a pigment, and having a region where an impact mark is formed when an impact force is applied. [2] The sintered compact according to [1] above, wherein the impact mark is a concave portion. [3] The sintered compact according to [1] or [2] above, wherein the stabilizer content is 3 mol% or more and 10 mol% or less. [4] The sintered compact according to any one of [1] to [3] above, wherein the stabilizer is two or more selected from the group consisting of yttria, calcia, magnesia, and ceria. [5] The sintered compact according to any one of [1] to [4] above, wherein the stabilizer is yttria and ceria. [6] The sintered compact according to any one of [1] to [5] above, wherein the yttria content is less than 1.5 mol%. [7] The sintered body according to any one of [1] to [6] above, wherein the ceria content is 2 mol% or more and 7.5 mol% or less. [8] The sintered body according to any one of [1] to [7] above, wherein the pigment is a metal oxide having a perovskite structure or a spinel structure. [9] The sintered body according to any one of [1] to [8] above, wherein the pigment is a manganese oxide having a perovskite structure or a spinel structure.

[10] The sintered body according to any one of [1] to [9] above, wherein the content of the pigment is 0.001% by mass or more.

[11] The sintered body according to any one of [1] to

[10] above, which contains alumina.

[12] The sintered body according to any one of [1] to

[11] above, wherein the Vickers hardness is 12 GPa or less.

[13] A member including the sintered body according to any one of [1] to

[12] above. [Effect of the Invention]

[0009] According to the present disclosure, at least one of a sintered body with improved impact resistance and a method for manufacturing the same can be provided by generating impact absorption by plastic deformation prior to the occurrence of brittle fracture against an impact exceeding the fracture resistance of the sintered body. [Brief Description of the Drawings]

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0011] Hereinafter, an example of an embodiment will be shown and described for the sintered body of the present disclosure.

[0012] The sintered body of the present embodiment contains zirconia containing a stabilizer and a pigment, and is characterized in that it has a region where an impact mark is formed when an impact force is applied.

[0013] The sintered body of the present embodiment preferably contains zirconia containing a stabilizer, and more preferably is a so-called zirconia sintered body having zirconia containing a stabilizer as a matrix (main phase). Since it contains a stabilizer, the sintered body of the present embodiment can also be regarded as a partially stabilized zirconia sintered body.

[0014] The sintered body of the present embodiment has a region where an impact mark is formed when an impact force is applied. One of the reasons for the improvement of the impact resistance of the sintered body of the present embodiment, that is, the reason for the improvement of the impact resistance, is that the region where the impact mark is formed (hereinafter, also referred to as the "plastic deformation region") exhibits a function of absorbing and dispersing the transmitted energy by the applied impact force. As a result, when an impact force is applied, at least plastic deformation occurs prior to the occurrence of brittle fracture, and as a result, the occurrence of brittle fracture is suppressed and the impact resistance is improved.

[0015] The sintered body of the present embodiment only needs to have a plastic deformation region in at least a part of the sintered body (that is, it may be a sintered body having a plastic deformation region), but may mainly consist of a plastic deformation region, or may be a sintered body consisting of a plastic deformation region.

[0016] "Impact force" refers to the force that transmits energy to the sintered body, particularly a dynamic external force, preferably an external force exceeding the fracture resistance of the sintered body, more preferably a dynamic external force exceeding the fracture resistance of the sintered body, and even more preferably a dynamic external force that exerts elastic energy on the sintered body.

[0017] "When an impact force is applied" refers to a state in which energy is applied to at least a part of the sintered body. For example, it includes a state in which energy is dynamically applied to the sintered body by contact of the sintered body with an object in contact, such as contact of the sintered body with the ground due to the fall of the sintered body or contact of a falling object with the sintered body.

[0018] "Impact mark" refers to the trace left on the sintered body when an impact force is applied, preferably the trace formed on the sintered body by the application of the impact force. In other words, the impact mark is the trace of plastic deformation that has occurred in the sintered body and is the trace of plastic deformation that occurred prior to fracture. As specific modes of the impact mark, concave portions, uneven portions, further concave portions, and even further concave portions along the direction of application of the impact force in the impact core part (described later) can be exemplified.

[0019] In the present embodiment, whether the sintered body has a plastic deformation region can be confirmed by applying an impact force (for example, a dynamic external force that causes the fracture of the sintered body) to the sintered body by any method. By applying an impact force to the sintered body and confirming the formation of an impact mark, which is a trace of plastic deformation such as a concave portion or uneven portion (particularly a trace of deformation that occurred prior to fracture), on the sintered body after the application, it can be confirmed that the sintered body has a plastic deformation region. In the sintered body of the present embodiment, the impact mark is formed due to plastic deformation, but may include defects such as cracks that occur thereafter (after the formation of the impact mark). On the other hand, if only defects such as cracks are present after the application of the impact force (that is, if only defects are confirmed without the formation of an impact mark due to plastic deformation) or if only deformation resulting from fracture such as Hertz fracture is present (that is, if only deformation formed by the progression of fracture such as cracks that occurred first is confirmed), it can be determined that there is no plastic deformation region.

[0020] As a preferable method for confirming the existence of the plastic deformation region, a DuPont type falling ball tester based on JIS K 5600 5-3 is used, and at room temperature, a 300 g falling weight is dropped from a falling height of 35 0 mm (hereinafter, also simply referred to as "falling ball test").

[0021] Figure 1 is a schematic diagram showing a falling ball test using a DuPont type falling ball tester. As shown in Figure 1, in the falling ball test, the measurement sample (101) has a protective tape (107) attached to its back surface and is placed on the sample stage (106) of a cylindrical falling ball tester, and is fixed to the sample stage by attaching a fixing tape (105) to its side surface. The falling weight consists of a weight (104) and a punch (102), and the punch (102) is placed on the surface of the measurement sample (101). The falling ball test may be performed by dropping the weight (104) from a height corresponding to the falling height (the height corresponding to the double arrow part in Figure 1; 350 mm) from the punch. The punch (102) has a cylindrical shape with a spherical (hemispherical) tip. Thereby, the same impact force as when a rigid ball of the same size as the spherical surface is dropped from the falling height can be applied to the measurement sample. By dropping the weight (104) along the guides (103a, 103b) of the DuPont type falling ball tester, a desired impact force can be applied to the measurement sample (101) through the punch (102). When not using the punch, a 300 g rigid ball having the same diameter as the spherical part (hemispherical part) of the punch may be dropped onto the measurement sample from a height corresponding to the falling height.

[0022] Figure 2 is a schematic diagram showing the appearance of the sintered body of the present embodiment after the ball drop test. As shown in Figure 2, it can be confirmed that impact marks are formed in the region (hereinafter also referred to as the "impact core part") of the sintered body of the present embodiment where the impact force by the dropping weight (punching die) is applied by the ball drop test. The impact marks in Figure 2 show a state where a concave part is formed near the impact core part, and it can be visually confirmed that it has a plastic deformation region. Although not shown in the figure, there may be defects such as cracks near the concave part. On the other hand, Figure 3 is a schematic diagram showing the appearance of a conventional sintered body after the ball drop test. As shown in Figure 3, in the conventional sintered body, the formation of impact marks at the impact core part cannot be confirmed, and only defects such as cracks are generated.

[0023] The presence or absence of the plastic deformation region may be confirmed by at least either visual observation or observation with an optical microscope, and further, by visual observation. As the observation magnification in the observation with an optical microscope, 1 to 100 times, preferably 10 to 30 times can be exemplified.

[0024] Although not shown in the figure, a conventional sintered body with high fracture toughness (for example, a sintered body with a fracture toughness value measured by the SEPB method exceeding 7 MPa·m 0.5 etc.) has no change in its appearance before and after the ball drop test, and the impact core part cannot be confirmed. In this case, the ball drop test is performed by increasing the dropping height until the impact core part can be confirmed, and by confirming the formation of impact marks such as the formation of a concave part in the confirmed impact core part and the occurrence of defects, the presence or absence of the plastic deformation region can also be confirmed. However, in the sintered body of the present embodiment, the presence or absence of the plastic deformation region may be confirmed by the ball drop test at a dropping height of 350 mm.

[0025] In the present embodiment, the ball drop test can be performed at room temperature (20 to 30 °C) using a DuPont type ball drop tester conforming to JIS K 5600 5-3. The following conditions can be cited as the conditions of the ball drop test. Dropping weight: (Shape) A spherical rigid ball with a diameter of 6.35 mm, or a cylindrical punching die with a spherical tip having a diameter of 6.35 mm (Mass) 300 g Dropping height: 350 mm Measurement sample: A plate-shaped body with a length of 40 mm, a width of 30 mm, and a thickness of 2 mm, and both surfaces are sintered bodies with a surface roughness Ra ≤ 0.02 μm

[0026] To prevent the scattering of the sample pieces, the measurement sample is placed by fixing one surface (a surface with a length of 40 mm and a width of 30 mm; the main surface) of the measurement sample and the sample stage of the ball-drop tester with double-sided tape. A fixing tape (protective tape) is attached along the longitudinal direction of the main surface that is opposite to the surface on which the measurement sample is fixed after placement, and the measurement sample is fixed (Figure 4). A ball-drop test may be performed on the fixed measurement sample

[0027] As the depth of the impact mark formed by the ball-drop test, for example, the depth of the deepest part of the impact mark (Figure 2: 204) with respect to the thickness of the sintered body (Figure 2: 203) is more than 0 and 3.5 or less, and further, more than 0.5 and 3 or less. Note that the depth (204) of the impact mark (concave part) in Figure 2 is shown with emphasis on the depth

[0028] In this embodiment, the depth of the impact mark can be measured using a general laser microscope (for example, VK-9500 / VK-9510, manufactured by Keyence Corporation). The observation magnification is 10 to 50 times, and further, 20 times, and the laser wavelength is 408 nm

[0029] Figure 5 shows a schematic diagram showing the method for measuring the depth of the impact mark. The measurement is performed by making a line profile (503A) passing through the center of the impact mark, and measuring the length (L1) of the deepest part in the Z-axis direction. Similarly, a similar line profile (503B) is made so as to be orthogonal to the above line profile, and the length (L2) of the deepest part in the Z-axis direction is measured. The average of the lengths of the two obtained deepest parts (= (L1 + L2) / 2) may be used as the depth (504) of the impact mark. The measurement conditions for measuring the length of the deepest part can be exemplified as 0.5 μm / step. Note that prior to the measurement, a standard sample attached to the apparatus with a known pattern length (for example, a Si substrate with a pattern engraved thereon) is measured, and the analysis accuracy may be adjusted

[0030] Analysis such as such line profiles and measurement of the deepest part in the Z-axis direction can be performed by image analysis using analysis software attached to the laser microscope (for example, software name: VK-H1A9VK ANALYZER Version 3.0.1.0).

[0031] The zirconia contained in the sintered body of this embodiment contains a stabilizer. The stabilizer only needs to contain an element having a function of stabilizing zirconia, and it is preferably two or more selected from the group of yttria (Y2O3), calcia (CaO), magnesia (MgO), and ceria (CeO2), more preferably contains at least yttria, and more preferably one or more selected from the group of calcia, magnesia, and ceria and yttria, and even more preferably yttria and ceria.

[0032] The stabilizer content is the total proportion (mol%) of the stabilizer in terms of oxide relative to the total of zirconia and the stabilizer in terms of oxide. The stabilizer content only needs to be an amount that partially stabilizes zirconia. For example, in a sintered body made of zirconia containing yttria and ceria (yttria and ceria stabilized zirconia sintered body), the stabilizer content can be obtained as {(Y2O3 + CeO2) / (Y2O3 + CeO2 + ZrO2)} × 100 (mol%). The stabilizer content is preferably 3 mol% or more and 10 mol% or less, more preferably 4 mol% or more and 7.5 mol% or less, even more preferably 4.2 mol% or more and 6.2 mol% or less, even more preferably 4.5 mol% or more and 6.0 mol% or less, and even more preferably 4.6 mol% or more and 5.5 mol% or less.

[0033] When yttria is included as a stabilizer, the yttria content is preferably less than 1.5 mol%, more preferably 1.3 mol% or less, and still more preferably 1.2 mol% or less. When ceria coexists with yttria, it is easier to obtain a sintered body by a simple method such as sintering under normal pressure, so the yttria content is preferably more than 0 mol% and 0.5 mol% or more, more preferably 0.6 mol% or more, particularly preferably 0.9 mol% or more, and still more preferably 1.0 mol% or more.

[0034] The sintered body of this embodiment only needs to satisfy the above-mentioned stabilizer content. When ceria is included as a stabilizer, the ceria content is arbitrary. Examples of the ceria content include 2 mol% or more and 7.5 mol% or less, more preferably 2.5 mol% or more and 6 mol% or less, and still more preferably 3 mol% or more and 5 mol% or less. When calcia is included as a stabilizer, examples of the calcia content include 2 mol% or more and 7.5 mol% or less, more preferably 2.5 mol% or more and 6 mol% or less. When magnesia is included as a stabilizer, examples of the magnesia content include 2 mol% or more and 7.5 mol% or less, more preferably 2 mol% or more and 6 mol% or less.

[0035] The sintered body of this embodiment preferably contains ceria and yttria as stabilizers. In this case, the ceria content is 2 mol% or more, 3 mol% or more, or 3.5 mol% or more, and 6 mol% or less, 5.5 mol% or less, or 4.5 mol% or less, and the yttria content is 0.1 mol% or more, 0.5 mol% or more, or 0.9 mol% or more, and less than 1.5 mol%, 1.3 mol% or less, or 1.15 mol% or less.

[0036] The content of each stabilizer is the ratio (mol%) of each stabilizer in terms of oxide to the total of zirconia and stabilizer in terms of oxide. For example, the yttria content in yttria-stabilized zirconia is the ratio (mol%) of yttria to the total of zirconia and yttria, and can be obtained from {(Y2O3 / (Y2O3+ZrO2))×100 (mol%)}. Also, the ceria content in ceria-stabilized zirconia is the ratio (mol%) of ceria to the total of zirconia and ceria, and can be obtained from {(CeO2 / (CeO2+ZrO2))×100 (mol%)}. Further, the yttria content in the sintered body of yttria- and ceria-stabilized zirconia can be obtained as {Y2O3 / (Y2O3+CeO2+ZrO2)}×100 (mol%). In this embodiment, ceria preferably consists of tetravalent cerium and more preferably does not contain trivalent cerium.

[0037] Due to the tendency that impact marks are more likely to occur due to plastic deformation, the ratio (molar ratio) of stabilizing elements other than yttrium to yttrium (Y) in the sintered body of this embodiment (hereinafter, also referred to as "S / Y ratio", and when the stabilizer other than yttrium is cerium (Ce) or the like, also referred to as "Ce / Y ratio", etc.) is preferably 1.2 or more and 5.0 or less, more preferably 1.4 or more and 4.5 or less, still more preferably 1.5 or more and 2.3 or less, and still more preferably 1.6 or more and 2.0 or less.

[0038] The sintered body of this embodiment contains a pigment. As a result, the sintered body exhibits a color tone different from the original color tone of zirconia. In this embodiment, the pigment only needs to contain an element having a function of coloring zirconia, and preferably contains at least one of a metal element and a lanthanoid rare earth element, more preferably contains at least one of a transition metal element and a lanthanoid rare earth element, and further preferably contains one or more selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), praseodymium (Pr), neodymium (Nd), europium (Eu), gadolinium (Gd), terbium (Tb), erbium (Er), and ytterbium (Yb), and even more preferably contains one or more selected from the group consisting of iron, cobalt, and manganese, and particularly preferably contains manganese. In another embodiment, the sintered body of this embodiment preferably contains, as a pigment, one or more elements selected from the group consisting of iron, cobalt, nickel, and manganese, and one or more elements selected from the group consisting of praseodymium, neodymium, europium, gadolinium, terbium, erbium, and ytterbium, and more preferably contains one or more elements selected from the group consisting of iron, cobalt, and manganese, and one or more elements selected from the group consisting of praseodymium, neodymium, gadolinium, terbium, and erbium.

[0039] More preferably, the sintered body of this embodiment contains, as a pigment, a metal oxide having a perovskite structure or a spinel structure, still more preferably contains a transition metal oxide having a perovskite structure or a spinel structure, and even more preferably contains a manganese oxide having a perovskite structure or a spinel structure.

[0040] Metal oxides having a perovskite structure are represented by ABO3, and A is one or more selected from the group consisting of calcium (Ca), strontium (Sr), barium (Ba), bismuth (Bi), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), holmium (Ho), europium (Eu), erbium (Er), terbium (Tb), praseodymium (Pr), and ytterbium (Yb); and B is one or more selected from the group consisting of vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and aluminum (Al). Preferably, they are represented by ABO3, and A is one or more selected from the group consisting of lanthanum, neodymium, gadolinium, praseodymium, and ytterbium; and B is one or more selected from the group consisting of manganese, iron, cobalt, and nickel. More preferably, they are represented by ABO3, and A is one or more selected from the group consisting of lanthanum, neodymium, gadolinium, praseodymium, and ytterbium; and B is manganese. Specific metal oxides having a perovskite structure include PrAlO3, NdAlO3, LaMnO3, GaMnO3, NdMnO3, PrMnO3, LaCoO3, GdCoO3, NdCoO3, PrCoO3, LaFeO3, GdFeO3, NdFeO3, PrFeO3, La(Co 0.5 Mn 0.5 )O3, Gd(Co 0.5 Mn 0.5 )O3, Nd(Co 0.5 Mn 0.5 )O3, Pr(Co 0.5 Mn 0.5 )O3, La(Fe 0.5 Mn 0.5 )O3, Gd(Fe 0.5 Mn 0.5 )O3, Nd(Fe 0.5 Mn 0.5 )O3, and one or more oxides selected from the group consisting of Pr(Fe 0.5 Mn 0.5 )O3 can be exemplified.

[0041] Metal oxides having a spinel structure are represented by AB2O4, and A and B are each one or more oxides selected from the group consisting of calcium, strontium, barium, bismuth, yttrium, lanthanum, neodymium, gadolinium, holmium, europium, erbium, terbium, praseodymium, ytterbium, vanadium, chromium, manganese, iron, cobalt, nickel, and aluminum. Preferably, they are represented by AB2O4, and A and B are each one or more oxides selected from the group consisting of lanthanum, neodymium, gadolinium, praseodymium, ytterbium, aluminum, manganese, iron, cobalt, and nickel. Further, they are represented by AB2O4, and A and B are each one or more oxides selected from the group consisting of lanthanum, neodymium, gadolinium, praseodymium, ytterbium, manganese, iron, cobalt, and nickel. More preferably, they are represented by AB2O4, and A and B are each one or more oxides selected from the group consisting of lanthanum, neodymium, gadolinium, praseodymium, ytterbium, iron, and manganese. Specific metal oxides having a spinel structure include at least any one selected from the group of CoAl2O4, Fe3O4, and Mn3O4 (i.e., Fe 2+ Fe 3+ 2O4 and Mn 2+ Mn 3+ 2O4), preferably at least any one of CoAl2O4 and Mn3O4, and preferably Mn3O4 can be exemplified.

[0042] Particularly preferred pigments include LaMnO3, GdMnO3, NdMnO3, PrMnO3, La(Co 0.5 Mn 0.5 )O3, Gd(Co 0.5 Mn 0.5 )O3, Nd(Co 0.5 Mn 0.5 )O3, Pr(Co 0.5 Mn 0.5 )O3, La(Fe 0.5 Mn 0.5 )O3, Gd(Fe 0.5 Mn 0.5 )O3, Nd(Fe 0.5 Mn0.5 )O3, Pr(Fe 0.5 Mn 0.5 )O3, and one or more oxides selected from the group consisting of Mn3O4, more preferably LaMnO3, GdMnO3, NdMnO3, PrMnO3, La(Co 0.5 Mn 0.5 )O3, and one or more oxides selected from the group consisting of Mn3O4 can be exemplified.

[0043] In the sintered body of the present embodiment, the smaller the content of the pigment, the easier it is for plastic deformation to occur. Therefore, the content of the pigment is preferably more than 0% by mass and 0.001% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more. If the sintered body has a plastic deformation region, the content of the pigment is arbitrary, but as the upper limit of the content of the pigment, for example, 5% by mass or less, further less than 3% by mass, still further 2.5% by mass or less, still further 2.0% by mass or less, still further 1.5% by mass or less, still further 1.0% by mass or less, and still further 0.7% by mass or less can be mentioned. The content of the pigment can be determined as the ratio of the total mass of the pigment in terms of oxide (hereinafter, the pigment in terms of oxide is also referred to as "M x O y ") to the mass of the sintered body in terms of oxide. The pigment in terms of oxide is, for example, neodymium is Nd2O3, lanthanum is La2O3, gadolinium is Gd2O3, praseodymium is Pr6O 11, cobalt may be Co3O4. Further, for example, when the sintered body of the present embodiment contains a metal oxide having a perovskite structure as a pigment and the balance is zirconia containing yttria and ceria as stabilizers, the content of the pigment can be determined as {(ABO3) / (ZrO2 + Y2O3 + CeO2 + ABO3)}×100 (mass%). Also, when the sintered body of the present embodiment contains a metal oxide having a spinel structure as a pigment and the balance is zirconia containing yttria and ceria as stabilizers, the content of the pigment can be determined as {(AB2O4) / (ZrO2 + Y2O3 + CeO2 + AB2O4)}×100 (mass%). As a specific content of the pigment, when the sintered body contains alumina and LaMnO3 which is a metal oxide having a perovskite structure as a pigment and the balance is zirconia containing yttria and ceria as stabilizers, the content of the pigment can be exemplified as {(LaMnO3) / (ZrO2 + Y2O3 + CeO2 + LaMnO3 + Al2O3)}×100 (mass%).

[0044] The sintered body of the present embodiment may contain alumina (Al2O3). Thereby, mechanical properties, for example, mechanical properties such as static strength, tend to be high, and the color tone of the sintered body tends to be light. Since the sintered body of the present embodiment may not contain alumina, the alumina content is 0 mass% or more. When alumina is contained, the alumina content exceeds 0 mass% and is less than 30 mass%, preferably exceeds 0 mass% and is 20 mass% or less, more preferably 0.005 mass% or more and 10 mass% or less. Also, the alumina content may be 0 mass% or more, more than 0 mass%, 0.5 mass% or more, or 1 mass% or more, and further may be 20 mass% or less, 17 mass% or less, 12 mass% or less, 10 mass% or less, or 8 mass% or less. The alumina content can be determined as the mass ratio of aluminum in terms of Al2O3 to the total amount of zirconia, the stabilizer in terms of oxide, and aluminum in terms of Al2O3. For example, when zirconia contains yttria and ceria as stabilizers, the alumina content is {Al2O3 / (ZrO2 + Y2O3 + CeO2 + M x O yIt can be determined as {(ZrO2 + stabilizer oxide) / (ZrO2 + stabilizer oxide + Al2O3)} × 100 (mass%). Alumina (Al2O3) has a great influence on the mechanical properties of the sintered body and has almost no effect on coloring zirconia. Therefore, in this embodiment, alumina, that is, aluminum that does not form a composite oxide with a metal element or the like, is not included in the pigment.

[0045] The sintered body of this embodiment preferably contains zirconia containing a stabilizer and is a so-called zirconia sintered body or a partially stabilized zirconia sintered body having zirconia containing a stabilizer as a matrix (main phase). When zirconia containing a stabilizer is used as the matrix (main phase), the mass ratio of zirconia containing a stabilizer in the sintered body (hereinafter, also referred to as "zirconia content") is 70% by mass or more, preferably 80% by mass or more, and more preferably exceeds 90% by mass. The sintered body has a zirconia content of 100% by mass or less, and when it consists only of zirconia containing a stabilizer, the mass ratio of zirconia is 100% by mass. The zirconia content can be determined as the ratio of the total mass of zirconia and the stabilizer in terms of oxide to the mass of the sintered body in terms of oxide. For example, when the sintered body contains alumina and the balance is zirconia containing yttria and ceria as stabilizers, the content of zirconia containing a stabilizer is {(ZrO2 + Y2O3 + CeO2) / (ZrO2 + Y2O3 + CeO2 + M x O y +Al2O3)} × 100 (mass%).

[0046] The sintered body of this embodiment may contain inevitable impurities such as hafnia (HfO2), but preferably does not contain anything other than pigments, stabilizers, zirconia, alumina, and inevitable impurities. In this embodiment, for calculating values affected by the composition such as the content and density of each component, hafnia (HfO2) may be regarded as zirconia (ZrO2) and these values may be calculated.

[0047] The sintered body of this embodiment preferably has a high density, and more preferably has a density corresponding to 98% or more in terms of relative density. In particular, when the alumina content increases, the density tends to decrease. For example, when the alumina content is 0% by mass or more and 10% by mass or less, the measured density has a lower limit of 5.85 g / cm 3 or more or 5.90 g / cm 3 or more, and an upper limit of 6.20 g / cm 3 or less, further 6.10 g / cm 3 or less, and even further 6.00 g / cm 3 or less. Also, when the alumina content exceeds 10% by mass and is 20% by mass or less, the measured density is 5.30 g / cm 3 or more and less than 5.85 g / cm 3 . When the alumina content exceeds 20% by mass and is less than 30% by mass, the measured density is 5.20 g / cm 3 or more and less than 5.30 g / cm 3 .

[0048] In this embodiment, the measured density can be obtained by the Archimedes method, and it is a value obtained as the mass obtained by mass measurement with respect to the volume obtained by the Archimedes method.

[0049] The crystal phase of zirconia in the sintered body of this embodiment preferably contains at least tetragonal crystal, and may be composed of tetragonal crystal and at least one of cubic crystal and monoclinic crystal.

[0050] The sintered body of this embodiment has a region (hereinafter, also referred to as "random orientation region") where the ratio of the intensity of the powder X-ray diffraction peak of the (004) plane of the tetragonal crystal to the intensity of the powder X-ray diffraction peak of the (220) plane of the tetragonal crystal (hereinafter, also referred to as "I (004) / (220) ") exceeds 0 and is 1.0 or less. It is more preferably composed of a random orientation region. The (220) plane of the tetragonal crystal (hereinafter, also referred to as "T 220 ") and the (004) plane of the tetragonal crystal (hereinafter, also referred to as "T 004 ") are crystal planes perpendicular to each other. Such I (004) / (220)Having a region is considered a sufficient condition for plastic deformation to occur when an impact force is applied. I in the randomly oriented region (004) / (220) is preferably 0.1 or more and 0.7 or less, and more preferably 0.2 or more and 0.6 or less.

[0051] When the sintered body of this embodiment absorbs or disperses energy by the application of an impact force, a change in crystal orientation may occur in the plastic deformation region. For example, when an impact force is applied, the crystal orientation in the plastic deformation region may increase. Further, when an impact force is applied (after the application of the impact force), T 220 with respect to the intensity of the powder X-ray diffraction peak of T 004 having a region where the intensity of the powder X-ray diffraction peak of T (004) / (220) is more than 1.0 and 10 or less (hereinafter, also referred to as "highly oriented region"). I in the highly oriented region

[0052] In this embodiment, the powder X-ray diffraction pattern (X-ray diffraction pattern) of the sintered body can be measured by a general crystalline analysis X-ray diffractometer (for example, apparatus name: X'pert PRO MPD, manufactured by Spectris).

[0053] Examples of the measurement conditions are as follows. X-ray source: CuKα ray (λ = 1.5405 Å) Tube voltage: 45 kV Tube current: 40 mA High-speed detector: X'Celerator + Ni filter Micro-optical system: Mono-capillary with a diameter of 0.1 mm Measurement angle: 70 to 80° Goniometer: Radius 240 mm

[0054] In the above measurement, the diffraction intensity (area intensity) of T 004 is taken as the diffraction intensity of the XRD peak having a peak top at 2θ = 72.5 ± 1°, and T 220The diffraction intensity (area intensity) is confirmed as the diffraction intensity of the XRD peak having a peak top at 2θ = 74 ± 1°, respectively.

[0055] The shape of the sintered body of the present embodiment includes, for example, at least any one selected from the group of spherical, substantially spherical, elliptical, disc-shaped, columnar, cubic, rectangular parallelepiped-shaped, polyhedral-shaped and substantially polyhedral-shaped. Further, any shape may be used as long as it can achieve a desired purpose such as various applications.

[0056] The color tone of the sintered body of the present embodiment is arbitrary, but the lightness L * a * b * in the (CIE1976 (L * a*b*) color space can be exemplified as 80 or more, further 85 or more, and still further 90 or more. Note that the upper limit of the lightness L * is 100 or less.

[0057] The lightness L * can be measured using a general spectrocolorimeter (for example, CM-700d, manufactured by Konica Minolta) in accordance with the method according to JIS Z8722. As the measurement conditions for the lightness L * the following conditions can be mentioned. The measurement is preferably a measurement using a black plate as the background (so-called black background measurement). Light source: F2 light source Field of view angle: 10° Measurement method: SCI

[0058] As the measurement sample, a disc-shaped sintered body having a diameter of 20 mm and a thickness of 2.7 mm may be used, and the surface to be evaluated may be mirror-polished (Ra ≦ 0.02 μm) to evaluate the color tone. Further, a diameter of 10 mm can be mentioned as the effective area for color tone evaluation.

[0059] For example, the color tone of the sintered body of the present embodiment is arbitrary, and the chroma a* and b* may be arbitrary values, and L * is 0 or more and 90 or less, a * is -5 or more and 15 or less, and b *It can be -1 or more and 40 or less. When the sintered body of this embodiment exhibits black (that is, when it is a black sintered body), it can have the following color tones.

[0060] 10 ≦ L * <60, -2 ≦ a * ≦ 2, and -2 ≦ b * ≦ 2, or 0 ≦ L * <10, -20 ≦ a * ≦ 20, and -20 ≦ b * ≦ 20 The sintered body of this embodiment preferably has a ball drop strength of 1 J or more, preferably 1.5 J or more. The ball drop strength is one of the indicators showing impact resistance, and the higher this value, the higher the impact resistance. As the ball drop strength of the sintered body, for example, cases where it is 10 J or less, 5 J or less, or 4 J or less can be exemplified.

[0061] The ball drop strength in this embodiment is the energy given by the falling weight to the sintered body when a falling weight is dropped from a predetermined ball drop height onto the sintered body and the sintered body reaches fracture. The ball drop strength can be obtained from the following formula, and preferably it is the value at a sample thickness of 2 mm.

[0062] Ball drop strength (J) = Falling weight mass (g) × Falling height (mm) × Gravitational acceleration (m / s 2 ) As the gravitational acceleration, 9.8 m / s 2 can be used.

[0063] The ball drop strength can be measured by a method similar to the above ball drop test except that the ball drop height is set to any height shown below. Ball drop height: 50 - 500 mm

[0064] The determination of breakage can be regarded as breakage having occurred when the measurement sample is in a state of being divided into two or more parts (Fig. 6(a)). On the other hand, when a crack that does not reach from one end to the other end occurs (Fig. 6(b)), it may be regarded that no breakage has occurred. When no breakage occurs in the ball-drop test at a specific drop height, the drop height may be increased in 50-mm increments up to 500 mm, and the ball-drop test may be repeated, and visual observation may be performed in the same manner until breakage occurs. In the present embodiment, for a measurement sample in which no breakage occurred in the ball-drop test at a drop height of 500 mm, the ball-drop strength may be expediently set to >5 J (more than 5 J).

[0065] The sintered body of the present embodiment preferably exhibits an improvement in impact resistance due to plastic deformation rather than an improvement in impact resistance due to an increase in hardness. Since there is a tendency for plastic deformation to occur easily, the Vickers hardness (Hv) of the sintered body of the present embodiment is preferably 12 GPa or less, more preferably 11 GPa or less, and still more preferably 10 GPa or less. It can be exemplified that the Vickers hardness is 5 GPa or more, 7 GPa or more, or 8 GPa or more.

[0066] In the present embodiment, the Vickers hardness can be measured by a method according to JIS R1610:2003. The following conditions can be exemplified as the measurement conditions for the Vickers hardness. Measurement sample: (sample thickness) 1.5 ± 0.5 mm (measurement surface roughness) Ra ≦ 0.02 μm Measurement load: 10 kgf

[0067] The measurement can be performed using a general Vickers testing machine (for example, MV-1, manufactured by Matsuzawa Co., Ltd.) equipped with a diamond square pyramid indenter. The measurement is performed by statically pressing the indenter into the measurement sample surface and visually measuring the diagonal length of the indentation formed on the measurement sample surface. Using the obtained diagonal length, the Vickers hardness can be determined from the following formula.

[0068] Hv = F / {d 2 / 2sin(α / 2)} In the above formula, Hv is the Vickers hardness (GPa), F is the measurement load (10 kgf), d is the diagonal length of the indentation mark (mm), and α is the opposite face angle of the indenter (136°).

[0069] As an index of the fracture resistance of the sintered body in the present embodiment, the fracture toughness value can be exemplified. The fracture toughness value is the value of the fracture toughness (MPa·m 0.5 ) measured by a method according to the SEPB method defined in JIS R 1607. The measurement of the fracture toughness value is performed using a columnar sintered body sample with a span between supports of 30 mm, a width of 4 mm, and a thickness of 3 mm, and the average value of 10 measurements may be taken as the fracture toughness value of the sintered body of the present embodiment. Note that JIS R 1607 defines two methods for measuring fracture toughness, the IF method and the SEPB method. Since the IF method is a simple measurement method, the variation in the measured values for each measurement is large. Therefore, the fracture toughness value in the present embodiment and the fracture toughness value measured by the IF method cannot be compared in terms of the absolute value of the values.

[0070] The sintered body of the present embodiment can be applied to conventional sintered bodies, particularly to applications of zirconia sintered bodies such as structural materials, optical materials, and dental materials, but can be used as a member that requires relatively high impact resistance, such as for decorative purposes, covers for accessories such as watches and casings, and exterior members of portable electronic devices such as mobile phones.

[0071] More preferable embodiments are as follows. (1) A sintered body containing one or more stabilizers selected from the group consisting of calcia, magnesia, and ceria, and yttria, the balance being zirconia, the content of the stabilizer being 2 mol% or more and 7.5 mol% or less, the content of yttria being more than 0 mol% and less than 1.5 mol%, and having a region where the intensity of the powder X-ray diffraction peak of the (004) plane of the tetragonal crystal with respect to the intensity of the powder X-ray diffraction peak of the (220) plane of the tetragonal crystal is more than 0 and 1.0 or less. (2) The sintered body according to (1) above, wherein the stabilizer is ceria. (3) The sintered body according to (1) or (2), wherein the total content of the stabilizer and the yttria content is 4 mol% or more and 7.5 mol% or less. (4) The sintered body according to any one of (1) to (3), containing one or more pigments selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), praseodymium (Pr), neodymium (Nd), europium (Eu), gadolinium (Gd), terbium (Tb), erbium (Er), and ytterbium (Tb). (5) The sintered body according to (4) above, wherein the pigment is an oxide having a perovskite structure or a spinel structure. (6) The sintered body according to (4) or (5), wherein the content of the pigment is more than 0% by mass and 5% by mass or less. (7) The sintered body according to any one of (1) to (6) above, wherein the sintered body consists of a region where the intensity of the powder X-ray diffraction peak of the cubic (004) plane with respect to the intensity of the powder X-ray diffraction peak of the cubic (220) plane is more than 0 and 1.0 or less. <Other embodiments> Another embodiment of the present disclosure is a sintered body characterized by having a region where an impact mark is formed when an impact force is applied.

[0072] Another embodiment of the present disclosure is a sintered body characterized in that an impact mark is formed when an impact force is applied.

[0073] Another embodiment of the present disclosure is a sintered body characterized by forming a recess by a ball drop test in which a 300 g dropping weight is dropped from a dropping height of 350 mm at room temperature using a DuPont type ball drop tester conforming to JIS K 5600 5-3. Another embodiment of the present disclosure is a sintered body having a region where the intensity of the powder X-ray diffraction peak of the cubic (004) plane with respect to the intensity of the powder X-ray diffraction peak of the cubic (220) plane is more than 0 and 1.0 or less, and after an impact force is applied, having a region where the intensity of the powder X-ray diffraction peak of the cubic (004) plane with respect to the intensity of the powder X-ray diffraction peak of the cubic (220) plane is more than 1.0 and 10 or less.

[0074] In these embodiments, the sintered body is preferably a zirconia sintered body containing a pigment, more preferably a partially stabilized zirconia sintered body, still more preferably a yttria and ceria stabilized zirconia sintered body containing a pigment, and still more preferably a yttria and ceria stabilized zirconia sintered body containing a pigment and having a yttria content of 1.0 mol% or more and less than 1.5 mol%.

[0075] Hereinafter, a method for manufacturing the sintered body of the present embodiment will be described.

[0076] The manufacturing method of the sintered body of the present embodiment is arbitrary as long as a sintered body satisfying the above requirements can be obtained. As an example of the manufacturing method of the sintered body of the present embodiment, a manufacturing method having a step of sintering a molded body containing two or more stabilizer sources, a pigment source, and zirconia can be exemplified.

[0077] The molded body to be subjected to the above step (hereinafter, also referred to as the "sintering step") is a molded body (compacted powder) containing two or more stabilizer sources, a pigment source, and zirconia.

[0078] The stabilizer source only needs to contain an element that becomes a stabilizer by sintering, and may be a compound containing one or more elements selected from the group of yttria, calcia, magnesia, and ceria, or yttrium (Y), calcium (Ca), magnesium (Mg), and cerium (Ce) that are precursors thereof (hereinafter, when the stabilizer is yttria, the stabilizer source is also referred to as a "yttria source", etc.). The stabilizer source is preferably a compound containing at least one of yttria and ceria, or yttrium and cerium that are precursors thereof, and more preferably at least one of a compound containing yttria and yttrium and a compound containing ceria and cerium.

[0079] The yttria source may be at least any one of yttrium and yttrium compounds serving as its precursors, and examples include one or more selected from the group consisting of yttrium chloride, yttria, and yttrium carbonate, and it is preferably yttria.

[0080] The ceria source may be at least any one of ceria and cerium compounds serving as its precursors, and examples include one or more selected from the group consisting of cerium chloride, ceria, and cerium carbonate, and it is preferably cerium chloride.

[0081] The calcia source may be at least any one of calcia and calcium compounds serving as its precursors, and examples include one or more selected from the group consisting of calcium chloride, calcia, calcium carbonate, and calcium hydrogen carbonate, and it is preferably calcia.

[0082] The magnesia source may be at least any one of magnesia and magnesium compounds serving as its precursors, and examples include one or more selected from the group consisting of magnesium chloride, magnesia, magnesium carbonate, and magnesium hydrogen carbonate, and it is preferably magnesia.

[0083] The content of the stabilizer source in the molded body may be equivalent to the stabilizer content of the target sintered body.

[0084] The pigment source may be at least any one of the pigment and its precursors. Examples of the pigment precursors include compounds containing at least any one of metal elements and lanthanoid rare earth elements, and one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, carbonates, oxalates, sulfates, acetates, nitrates, chlorides, fluorides, bromides, and iodides of at least any one of metals and lanthanoid rare earths can be exemplified. Preferably, one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, and carbonates of at least any one of transition metals and lanthanoid rare earths are included. Specific examples of the pigment precursors include two or more selected from the group consisting of manganese oxide, iron oxide, cobalt oxide, lanthanum oxide, neodymium oxide, gadolinium oxide, and praseodymium oxide.

[0085] When the pigment is a metal oxide having a perovskite structure or a spinel structure, the pigment can be obtained by mixing one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, carbonates, oxalates, sulfates, acetates, nitrates, chlorides, fluorides, bromides, and iodides of transition metals, and one or more selected from the group consisting of oxides, hydroxides, oxyhydroxides, carbonates, oxalates, sulfates, acetates, nitrates, chlorides, fluorides, bromides, and iodides of transition metals, and firing in air at 1200 °C to 1500 °C.

[0086] The content of the pigment source in the green compact may be equivalent to the content of the pigment in the target sintered body.

[0087] When a sintered body containing alumina is used, the green compact may contain an alumina source. The alumina source is at least one of alumina (Al2O3) and a compound containing aluminum (Al) that is a precursor thereof, and examples thereof include one or more selected from the group consisting of aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum hydroxide, and alumina, and alumina is preferable.

[0088] The content of the alumina source in the green compact may be equivalent to the alumina content of the target sintered body.

[0089] For improving the shape stability, the green compact may contain a binder. The binder may be an organic binder used for forming ceramics, and examples thereof include one or more selected from the group consisting of acrylic resins, polyolefin resins, waxes, and plasticizers. As the content of the binder, 25 to 65% by volume can be exemplified as the ratio of the binder in the volume of the green compact.

[0090] The shape of the green compact may be any shape according to the purpose in consideration of the shrinkage due to sintering, and examples thereof include at least one selected from the group consisting of spherical, substantially spherical, elliptical, disk-shaped, columnar, cubic, rectangular parallelepiped-shaped, polyhedral-shaped, and substantially polyhedral-shaped.

[0091] The method for manufacturing the formed body is arbitrary, and examples include mixing and forming zirconia, a stabilizer source, a pigment source, and, if necessary, an alumina source by any method. Further, instead of or in addition to zirconia and a stabilizer source, stabilized zirconia may be used.

[0092] When using stabilized zirconia as zirconia, the method for incorporating the stabilizer into the zirconia is arbitrary. For example, it may involve mixing a hydrated zirconia sol with a stabilizer source equivalent to the desired stabilizer content, followed by drying, calcination, and water washing.

[0093] The mixing method is arbitrary, preferably at least one of dry mixing or wet mixing, more preferably wet mixing, and even more preferably wet mixing using a ball mill.

[0094] The forming method may be any known forming method, preferably at least one selected from the group consisting of uniaxial pressing, isostatic pressing, injection molding, extrusion molding, rolling granulation, and casting molding, more preferably at least one of uniaxial pressing and isostatic pressing, and even more preferably at least one of cold isostatic pressing and uniaxial pressing (powder pressing).

[0095] In the sintering step, the formed body is sintered to obtain a sintered body. The sintering method is arbitrary, and examples of known sintering methods include atmospheric pressure sintering, pressure sintering, vacuum sintering, etc. Preferred sintering methods include atmospheric pressure sintering. Since it is simple, it is preferable that the sintering method is only atmospheric pressure sintering. Thereby, the sintered body of the present embodiment can be obtained as a so-called atmospheric pressure sintered body. Atmospheric pressure sintering is a method of sintering by simply heating the formed body (or calcined body) without applying an external force during sintering.

[0096] The conditions for atmospheric sintering are as follows: the sintering temperature can be exemplified as 1250°C or higher and 1600°C or lower, preferably 1300°C or higher and 1580°C or lower, 1300°C or higher and 1560°C or lower. Further, as the sintering atmosphere, at least one of an air atmosphere and an oxygen atmosphere can be mentioned, and an air atmosphere is preferable. Also, as the sintering atmosphere, at least one of an air atmosphere and an oxygen atmosphere can be mentioned, and an air atmosphere is preferable. Thereby, when ceria is included as a stabilizer, the ceria consists of tetravalent cerium (Ce 4+ ). [Examples]

[0097] Hereinafter, this embodiment will be specifically described by way of examples. However, this embodiment is not limited to these examples. (Confirmation of plastic deformation region) The presence or absence of the plastic deformation region of the sintered body sample was confirmed by a falling ball test using a DuPont type falling ball tester (apparatus name: H-50, manufactured by Toyo Seiki Co., Ltd.) conforming to JIS K 5600 5-3. The test conditions are shown below. Falling weight: (shape) a spherical hard ball with a diameter of 6.35 mm, that is, a cylindrical punch with a height of 10 mm having a spherical tip with a diameter of 6.35 mm (mass) 300 g, that is, a weight made of SUS, in the shape of a rectangular parallelepiped with a width of 80 mm × a thickness of 20 mm × a height of 30 mm and a mass of 300 g Falling ball height: 350 mm Measurement sample: a plate shape with a length of 40 mm × a width of 30 mm × a thickness of 2 mm, and a sintered body with a surface roughness Ra ≤ 0.02 μm on both surfaces of (the surface with a length of 40 mm × a width of 30 mm; the main surface) For the measurement sample, in order to prevent the sample pieces from scattering, one surface (the surface with a length of 40 mm × a width of 30 mm) of the measurement sample and the sample stage of the falling ball tester were fixed with double-sided tape, and the measurement sample was placed. Tape was attached along the longitudinal direction of the surface of the measurement sample that was opposite to the fixed surface after placement, and the measurement sample was fixed). The punch was placed so that the falling weight would fall near the center of the measurement sample after fixation, and the falling ball test was carried out.

[0098] (Measurement of falling ball strength) The ball-drop strength was measured in the same manner as the ball-drop test for the confirmation of the plastic deformation region, except that the ball-drop height was changed. That is, the state of the measurement sample after dropping the dropping weight was visually confirmed, and the ball-drop strength at the ball-drop height at which fracture occurred in the measurement sample was determined from the following formula. Ball-drop strength (J) = dropping weight mass (g) × dropping height (mm) × gravitational acceleration (9.8 m / s 2 ) For the determination of fracture, it was regarded that fracture had occurred when the measurement sample was divided into two or more pieces. Note that the occurrence of extremely minute fragments such as chipping and the state in which the measurement sample maintained a plate shape were not regarded as fracture. When fracture did not occur in the ball-drop test at a specific dropping height, the ball-drop test was repeated with the dropping height increased in 50 mm increments up to 500 mm until fracture occurred. For the measurement samples in which fracture did not occur in the ball-drop test at a dropping height of 500 mm, the ball-drop strength was arbitrarily set to >5 J (more than 5 J).

[0099] (Impact mark depth) The depth of the impact mark was measured at an observation magnification of 20 times using a general laser microscope (device name: VK-9500 / VK-9510, manufactured by Keyence Corporation). A line profile passing through the center of the impact mark was made, and after measuring the length (L1) of the deepest part in the Z-axis direction at 0.5 μm / step, a line profile was made in the same manner so as to be orthogonal to the said line profile, and the length (L2) of the deepest part in the Z-axis direction was measured. The average of the lengths of the two deepest parts obtained (=(L1 + L2) / 2) was taken as the depth of the impact mark.

[0100] (Vickers hardness) The Vickers hardness was measured using a general Vickers testing machine (device name: MV-1, manufactured by Matsuzawa Corporation) equipped with a diamond square pyramid indenter. The indenter was statically pressed into the surface of the measurement sample, the diagonal length of the indentation mark formed on the surface of the measurement sample was visually measured, and the Vickers hardness (GPa) was determined from the above formula using the obtained diagonal length.

[0101] (Density) The measured density of the sintered body sample was determined as the ratio of the volume measured by the Archimedes method to the mass measured by mass measurement (g / cm 3 ).

[0102] (I (004) / (220) ) The diffraction intensities of the crystal phases, T 004 and T 220 of the sintered body sample were measured using micro-XRD (equipment name: X'pert PRO MPD, manufactured by Spectris). The measurement conditions are described below. X-ray source: CuKα ray (λ = 1.5405 Å) Tube voltage: 45 kV Tube current: 40 mA High-speed detector: X'Celerator + Ni filter Micro-optical system: Mono-capillary with a diameter of 0.1 mm Measurement angle: 70 - 80° Goniometer: Radius 240 mm Before the test and after confirming the plastic deformation region, micro-XRD measurements were performed on the core-punching part and the part other than the core-punching part in the measurement sample. I (004) / (220) was calculated according to the following formula. I (004) / (220) =(Diffraction intensity of T 004 ) / (Diffraction intensity of T 220 )

[0103] (Measurement of color tone) The color tone of the sintered body sample was measured by a method conforming to JIS Z8722. For the measurement, a general spectro-colorimeter (equipment name: CM-700d, manufactured by Konica Minolta) was used, and black background measurement using a black plate on the back was performed. The measurement conditions are as follows. Light source: F2 light source Field of view angle: 10° Measurement method: SCI For the sintered body sample, a disc-shaped one with a diameter of 20 mm and a thickness of 2.7 mm was used. One surface of the sintered body sample was mirror-polished (Ra ≤ 0.02 μm), and the color tone was evaluated using this surface as the evaluation surface. The effective area for color tone evaluation was 10 mm in diameter. <Synthesis of pigment> Synthesis Example 1 After treating lanthanum oxide (La2O3) at 700 °C in the atmosphere, the lanthanum oxide and manganese sesquioxide (Mn3O4) were mixed so that La:Mn = 1:1 to obtain a mixed powder. The obtained mixed powder was heat-treated at 1400 °C for 2 hours in the atmosphere and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated at 1450 °C for 4 hours in the atmosphere to obtain LaMnO3.

[0104] Synthesis Example 2 NdMnO3 was obtained in the same manner as in Synthesis Example 1, except that neodymium oxide (Nd2O3) was used instead of lanthanum oxide and neodymium oxide and manganese sesquioxide were mixed so that Nd:Mn = 1:1.

[0105] Synthesis Example 3 GdMnO3 was obtained in the same manner as in Synthesis Example 1, except that gadolinium oxide (Gd2O3) was used instead of lanthanum oxide and gadolinium oxide and manganese sesquioxide were mixed so that Gd:Mn = 1:1.

[0106] Synthesis Example 4 After treating praseodymium oxide (Pr6O 11 ) at 700 °C in the atmosphere, the praseodymium oxide and manganese sesquioxide were mixed so that Pr:Mn = 1:1 to obtain a mixed powder. The obtained mixed powder was heat-treated at 1330 °C for 1 hour in the atmosphere and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated at 1450 °C for 4 hours in the atmosphere to obtain PrMnO3.

[0107] Synthesis Example 5 A mixed powder was obtained in the same manner as in Synthesis Example 1, except that cobalt sesquioxide (Co3O4) was used instead of manganese sesquioxide and lanthanum oxide and cobalt sesquioxide were mixed so that La:Co = 1:1. The obtained mixed powder was heat-treated at 1350 °C for 2 hours in the atmosphere and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated at 1450 °C for 4 hours in the atmosphere to obtain LaCoO3.

[0108] Synthesis Example 6 A mixed powder was obtained in the same manner as in Synthesis Example 1, except that cobalt sesquioxide was used in addition to manganese sesquioxide, and lanthanum oxide, manganese sesquioxide and cobalt sesquioxide were mixed so that La:Mn:Co = 1:0.5:0.5. The obtained mixed powder was heat-treated in air at 1350 °C for 2 hours and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated in air at 1450 °C for 4 hours to obtain La(Co 0.5 Mn 0.5 )O3 was obtained.

[0109] Synthesis Example 7 A mixed powder was obtained in the same manner as in Synthesis Example 1, except that iron oxide (Fe2O3) was used instead of manganese sesquioxide, and lanthanum oxide and iron oxide were mixed so that La:Fe = 1:1. The obtained mixed powder was heat-treated in air at 1350 °C for 2 hours and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated in air at 1450 °C for 4 hours to obtain LaFeO3.

[0110] Synthesis Example 8 After treating neodymium oxide (Nd2O3) in air at 700 °C, the neodymium oxide and aluminum oxide were mixed so that Nd:Al = 1:1 to obtain a mixed powder. The obtained mixed powder was heat-treated in air at 1330 °C for 1 hour and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated in air at 1450 °C for 4 hours to obtain NdAlO3.

[0111] Synthesis Example 9 After treating praseodymium oxide (Pr6O 11 ) in air at 700 °C, the praseodymium oxide and aluminum oxide were mixed so that Pr:Al = 1:1 to obtain a mixed powder. The obtained mixed powder was heat-treated in air at 1330 °C for 1 hour and then cooled to room temperature. After cooling, it was pulverized and mixed, and this was heated in air at 1450 °C for 4 hours to obtain PrAlO3.

[0112] Example 1 An aqueous solution of zirconium oxychloride was subjected to a hydrolysis reaction to obtain a hydrated zirconia sol. Yttria and cerium chloride heptahydrate were added to and mixed with the hydrated zirconia sol so that the yttria concentration was 1.1 mol% and the ceria concentration was 3.6 mol%, respectively. After mixing, it was dried in air and calcined in air at 1155 °C for 2 hours to obtain a calcined powder of yttria-ceria stabilized zirconia. The obtained calcined powder was washed with pure water and dried to obtain a zirconia powder composed of yttria and ceria stabilized zirconia with a yttria content of 1.1 mol% and a ceria content of 3.6 mol%.

[0113] The obtained zirconia powder and LaMnO3 obtained in Synthesis Example 1 were added to pure water to form a slurry so that the LaMnO3 content was 0.3 mass%, and this was pulverized and mixed for 22 hours using a ball mill with a zirconia ball having a diameter of 10 mm as a pulverization medium. The slurry after pulverization and mixing was dried to obtain the zirconia powder of this Example containing 0.3 mass% of LaMnO3 and the balance being yttria and ceria stabilized zirconia with a yttria content of 1.1 mol% and a ceria content of 3.6 mol%.

[0114] After granulating the obtained powder into powder granules, it was filled into a plate-shaped mold measuring 40 mm in length × 30 mm in width, and a plate-shaped compact was obtained by uniaxial pressing at a molding pressure of 50 MPa and cold isostatic pressing (CIP) treatment at a molding pressure of 196 MPa. The obtained compact was sintered under the following conditions to obtain a sintered body of this Example composed of yttria-ceria stabilized zirconia containing 0.3 mass% of LaMnO3 and the balance being yttria with a content of 1.1 mol% and ceria with a content of 3.6 mol%. The sintering conditions are shown below. Sintering method: Normal pressure sintering Sintering atmosphere: Air atmosphere Sintering temperature: 1550 °C Sintering time: 2 hours

[0115] Example 2 Except for using NdMnO₃ obtained in Synthesis Example 2 so that the NdMnO₃ content is 0.3% by mass instead of LaMnO₃, in the same manner as in Example 1, a sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of NdMnO₃ and the balance being a yttria content of 1.1 mol% and a ceria content of 3.6 mol% was obtained.

[0116] Example 3 Except for using GdMnO₃ obtained in Synthesis Example 3 so that the GdMnO₃ content is 0.3% by mass instead of LaMnO₃, in the same manner as in Example 1, a sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of GdMnO₃ and the balance being a yttria content of 1.1 mol% and a ceria content of 3.6 mol% was obtained.

[0117] Example 4 Except for using PrMnO₃ obtained in Synthesis Example 2 so that the PrMnO₃ content is 0.3% by mass instead of LaMnO₃, in the same manner as in Example 1, a sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of PrMnO₃ and the balance being a yttria content of 1.1 mol% and a ceria content of 3.6 mol% was obtained.

[0118] Example 5 Except for using Mn₃O₄ (product name: Braunox, manufactured by Tosoh Corporation) so that the Mn₃O₄ content is 0.26% by mass instead of LaMnO₃ and setting the sintering temperature to 1450 °C, in the same manner as in Example 1, a sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.26% by mass of Mn₃O₄ and the balance being a yttria content of 1.1 mol% and a ceria content of 3.6 mol% was obtained.

[0119] Example 6 Except that Mn₃O₄ was used such that the Mn₃O₄ content was 0.09% by mass and the sintering temperature was 1450 °C instead of LaMnO₃, in the same manner as in Example 1, a sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.09% by mass of Mn₃O₄ and the balance being an yttria content of 1.1 mol% and a ceria content of 3.6 mol% was obtained.

[0120] Example 7 Except that the LaMnO₃ obtained in Synthesis Example 1 was used such that the LaMnO₃ content was 1% by mass, in the same manner as in Example 1, a sintered body of this example composed of yttria-ceria stabilized zirconia containing 1% by mass of LaMnO₃ and the balance being an yttria content of 1.1 mol% and a ceria content of 3.6 mol% was obtained.

[0121] Comparative Example 1 Except that cerium chloride heptahydrate was not used, yttria was added to the hydrated zirconia sol such that the yttria concentration was 3.0 mol%, and the LaMnO₃ obtained in Synthesis Example 1 was used such that the LaMnO₃ content was 1% by mass, in the same manner as in Example 1, a sintered body of this comparative example composed of yttria-stabilized zirconia containing 1% by mass of LaMnO₃ and the balance being an yttria content of 3.0 mol% was obtained.

[0122] Comparative Example 2 Except that the LaMnO₃ obtained in Synthesis Example 1 was used such that the LaMnO₃ content was 3% by mass and the sintering temperature was 1450 °C, in the same manner as in Example 1, a sintered body of this comparative example composed of yttria-ceria stabilized zirconia containing 3% by mass of LaMnO₃ and the balance being an yttria content of 1 mol% and a ceria content of 3.6 mol% was obtained.

[0123] These evaluation results are shown in the following table.

[0124]

Table 1

[0125] Examples 1 to 7 were all sintered bodies with a zirconia content of 95% by mass and a cubic crystal phase, and had a density corresponding to 98% or more as the relative density. All of the sintered bodies contained a manganese oxide having a perovskite structure or a spinel structure as a pigment, and the lightness L * was 2 or more and 52 or less and exhibited black color. Since the sintered body of Comparative Example 2 contained a large amount of pigment, defects such as cracks occurred during sintering, and evaluation of density and the like could not be performed.

[0126]

Table 2

[0127] In the above table, in the state after the ball drop test, the column of "formation of impact mark" was marked as "〇" when an impact mark could be confirmed, and the column of those where no impact mark could be confirmed was marked as "×". Fig. 7 shows the appearance of the sintered body after the ball drop test of Example 1 by optical microscope observation. From Fig. 7, it can be confirmed that the region where the dropping weight contacted by the ball drop test formed an impact mark (concave portion) without accompanying destruction such as cracks, that is, an impact mark (concave portion) as a trace of plastic deformation can be confirmed. The white circular region observed near the center of the impact mark in Fig. 7 is a reflection image generated during the photographing of the optical microscope observation image, and the region exhibits the same color tone as other regions of the impact mark. The impact mark was a round concave portion with a diameter of about 3 mm. In any of the sintered bodies of Examples 1 to 7, an impact mark as a trace of plastic deformation similar to that in Fig. 7 could be confirmed visually.

[0128] On the other hand, it was confirmed that the sintered body of Comparative Example 1 containing only yttria as a stabilizer only had cracks progressing by the ball drop test and had no plastic deformation region.

[0129] Example 8 Zirconia powder, 3% by mass of α-alumina powder, and LaMnO₃ obtained in Synthesis Example 1 were added to pure water to form a slurry such that the LaMnO₃ content was 1% by mass, and a sintered body of this Example composed of yttria-ceria stabilized zirconia containing 3% by mass of alumina, 1% by mass of LaMnO₃, and the balance being 1.1 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1 except that the sintering temperature was 1450°C.

[0130] Example 9 Zirconia powder, 3% by mass of α-alumina powder, and LaMnO₃ obtained in Synthesis Example 1 were added to pure water to form a slurry such that the LaMnO₃ content was 2% by mass, and a sintered body of this Example composed of yttria-ceria stabilized zirconia containing 3% by mass of alumina, 2% by mass of LaMnO₃, and the balance being 1.1 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1 except that the sintering temperature was 1450°C.

[0131] Example 10 Zirconia powder, 5% by mass of α-alumina powder, and instead of LaMnO₃, NdAlO₃ obtained in Synthesis Example 8 was used such that the NdAlO₃ content was 0.3% by mass, and a sintered body of this Example composed of yttria-ceria stabilized zirconia containing 5% by mass of alumina, 0.3% by mass of NdAlO₃, and the balance being 1.0 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1.

[0132] The evaluation results of these Examples are shown in the following table.

[0133]

Table 3

[0134] Examples 8 to 10 were all sintered bodies with a zirconia content of 95% by mass and a cubic crystal phase, and had a density corresponding to 98% or more as the relative density. All of the sintered bodies contained a metal oxide having a perovskite structure as a pigment and also contained alumina. The sintered bodies of Examples 8 and 9 had a gray color tone, and the sintered body of Example 10 had a white color tone, showing a lighter color tone (gray) compared to the sintered bodies of Example 1 and the like.

[0135]

Table 4

[0136] For all of the sintered bodies of Examples 8 to 10, impact marks as traces of plastic deformation similar to those in FIG. 7 could be visually confirmed.

[0137] Example 11 A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of LaCoO3 and the balance being 1.1 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1, except that LaCoO3 obtained in Synthesis Example 5 was used so that the LaCoO3 content was 0.3% by mass instead of LaMnO3.

[0138] Example 12 LaMnO3 was replaced with La(Co 0.5 Mn 0.5 )O3 obtained in Synthesis Example 6 so that the content of La(Co 0.5 Mn 0.5 )O3 was 0.3% by mass. A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of La(Co 0.5 Mn 0.5 )O3 and the balance being 1.1 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1.

[0139] Example 13 A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of LaFeO₃ with the balance being 1.1 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1, except that LaFeO₃ obtained in Synthesis Example 7 was used so that the LaFeO₃ content was 0.3% by mass instead of LaMnO₃.

[0140] Example 14 A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of NdAlO₃ with the balance being 1.0 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1, except that NdAlO₃ obtained in Synthesis Example 8 was used so that the NdAlO₃ content was 0.3% by mass instead of LaMnO₃.

[0141] The evaluation results of these examples are shown in the following table.

[0142] Example 15 A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.3% by mass of PrAlO₃ with the balance being 1.0 mol% of yttria content and 3.6 mol% of ceria content was obtained in the same manner as in Example 1, except that PrAlO₃ obtained in Synthesis Example 9 was used so that the PrAlO₃ content was 0.3% by mass instead of LaMnO₃.

[0143] Example 16 Zirconia powder composed of yttria-ceria stabilized zirconia with 1.0 mol% of yttria content and 4.0 mol% of ceria content was obtained in the same manner as in Example 1, except that yttrium oxide and cerium chloride heptahydrate were added to and mixed with the hydrated zirconia sol so that the yttria concentration was 1.0 mol% and the ceria concentration was 4.0 mol%, and α-alumina powder was not used.

[0144] A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.4% by mass of Mn₃O₄ with the balance being 1.0 mol% of yttria content and 4.0 mol% of ceria content was obtained in the same manner as in Example 1, except that Mn₃O₄ was used such that the Mn₃O₄ content was 0.4% by mass and the sintering temperature was 1500 °C.

[0145] Example 17 A sintered body of this example composed of yttria-ceria stabilized zirconia containing 0.5% by mass of CoAl₂O₄ with the balance being 1.0 mol% of yttria content and 4.0 mol% of ceria content was obtained in the same manner as in Example 16, except that CoAl₂O₄ was used such that the CoAl₂O₄ content was 0.5% by mass.

[0146] The evaluation results of these examples are shown in the following table.

[0147]

Table 5

[0148] Examples 11 to 17 were all sintered bodies with a zirconia content of 95% by mass whose crystal phase was tetragonal and had a density corresponding to 98% or more as the relative density. All of the sintered bodies were sintered bodies containing a transition metal oxide having a perovskite structure or a spinel structure as a pigment. Example 11 was brown, Example 12 was black, Example 13 was light yellow, Example 14 was orange, and Example 15 was cream-colored.

[0149]

Table 6

[0150] For the sintered bodies of Examples 11 to 17, impact marks as traces of plastic deformation similar to those in Fig. 7 could be confirmed visually.

[0151] Example 18 Yttrium oxide and cerium chloride heptahydrate were added to and mixed with a hydrated zirconia sol so that the yttria concentration was 1.0 mol% and the ceria concentration was 4.0 mol%, and zirconia powder composed of yttria-ceria stabilized zirconia with a yttria content of 1.0 mol% and a ceria content of 4.0 mol% was obtained in the same manner as in Example 1 except that α-alumina powder was not used.

[0152] Except that Mn3O4 was used so that the Mn3O4 content was 0.4 mass%, GdMnO3 obtained in Synthesis Example 3 was used so that the GdMnO3 content was 0.2 mass%, and the sintering temperature was 1500 °C, in the same manner as in Example 1, a sintered body of this example containing 0.4 mass% of Mn3O4 and 0.2 mass% of GdMnO3 and the balance being yttria-ceria stabilized zirconia with a yttria content of 1.0 mol% and a ceria content of 4.0 mol% was obtained.

[0153] Example 19 Yttrium oxide and cerium chloride heptahydrate were added to and mixed with a hydrated zirconia sol so that the yttria concentration was 1.0 mol% and the ceria concentration was 4.0 mol%, and zirconia powder composed of yttria-ceria stabilized zirconia with a yttria content of 1.0 mol% and a ceria content of 4.0 mol% was obtained in the same manner as in Example 1 except that α-alumina powder was not used.

[0154] Except that Mn3O4 was used so that the Mn3O4 content was 0.4 mass%, GdMnO3 obtained in Synthesis Example 3 was used so that the GdMnO3 content was 0.4 mass%, and the sintering temperature was 1500 °C, in the same manner as in Example 1, a sintered body of this example containing 0.4 mass% of Mn3O4 and 0.4 mass% of GdMnO3 and the balance being yttria-ceria stabilized zirconia with a yttria content of 1.0 mol% and a ceria content of 4.0 mol% was obtained.

[0155] The evaluation results of these examples are shown in the following table.

[0156]

Table 7

[0157] Examples 18 and 19 were both sintered bodies containing a metal oxide having a perovskite structure and a metal oxide having a spinel structure as pigments, and having a zirconia content of 95% by mass with a crystal phase consisting of tetragonal crystal, and having a density corresponding to 98% or more as the relative density. Also, both of the sintered bodies exhibited black color.

[0158]

Table 8

[0159] In the sintered bodies of Examples 18 and 19, impact marks as traces of plastic deformation similar to those in Fig. 7 could be confirmed visually.

[0160] Measurement Example Platelike sintered bodies measuring 40 mm in length × 30 mm in width × 0.5 mm in thickness were obtained in the same manner as in Examples 1, 3, and 4, except that the amount of raw material powder used was adjusted and reduced to make the sample thickness thinner. Evaluation was performed in the same manner as in the above (confirmation of plastic deformation region) and (measurement of ball drop strength), except that this was used as the measurement sample.

[0161] The results are shown in the following table together with the results of Comparative Example 3.

[0162]

Table 9

[0163] In all of the sintered compacts of the examples, impact marks as traces of plastic deformation similar to those in Fig. 7 could be visually confirmed. Furthermore, the thickness of the samples of these examples was 0.5 mm, which is 1 / 4 of the sample thickness of Comparative Example 3 (sample thickness: 2.0 mm). Nevertheless, it was confirmed that they had a higher ball-drop strength than Comparative Example 3.

Explanation of Signs

[0164] 100: External view showing the outline of the ball-drop test 101: Sintered compact 102: Punch 103a, 103b: Guides 104: Drop weight 105: Fixing tape 106: Sample stage of the ball-drop tester 107: Protection tape 200: Sintered compact of this embodiment after the drop test 201: Sintered compact 202: Impact mark (concave part) 203: Depth of the impact mark (concave part) 300: Conventional sintered compact after the drop test 301: Sintered compact 302: Defect (crack) 400: Diagram showing the installation state of the sintered compact on the sample stage of the drop tester 401: Sintered compact 402: Fixing tape 403: Sample stage of the ball-drop tester 404: Double-sided tape (protection tape) 500: Diagram showing the method for measuring the impact mark depth 501: Sintered compact 502: Impact mark (concave part) 503A,B: Line profile 504: Depth of the deepest part (L1 or L2) 601: Sintered compact in a divided state 602: Defect (crack) 701: Sintered compact 702: Impact mark (concave part)

Claims

1. A sintered body comprising more than 0 mass % and less than 3 mass % of zirconia containing two or more stabilizers selected from the group consisting of yttria, calcia, magnesia, and ceria, alumina, and a pigment, and having a region in which an impact mark is formed when an impact force is applied.

2. The sintered body according to claim 1 , wherein the impact mark is a recess.

3. 3. The sintered body according to claim 1, wherein the stabilizer content is from 3 mol % to 10 mol %.

4. 4. The sintered body according to claim 1, wherein the stabilizer is yttria and ceria.

5. 5. The sintered body according to claim 4, wherein the molar ratio of the stabilizing element other than yttrium to yttrium (Y) is 1.2 or more and 5.0 or less.

6. 6. The sintered body according to claim 1, wherein the yttria content is less than 1.5 mol%.

7. The sintered body according to claim 1 , having a ceria content of 2 mol % or more and 7.5 mol % or less.

8. 8. The sintered body according to claim 1, wherein the pigment is a metal oxide having a perovskite structure or a spinel structure.

9. 9. The sintered body according to claim 1, wherein the pigment is a manganese oxide having a perovskite structure or a spinel structure.

10. The sintered body according to claim 1 , wherein the pigment content is 0.001% by mass or more.

11. The sintered body according to claim 1 , having an alumina content of more than 0 mass% and less than 30 mass%.

12. 12. The sintered body according to claim 1, having a Vickers hardness of 12 GPa or less.

13. A member comprising the sintered body according to any one of claims 1 to 12.

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