Sintered body with excellent impact resistance

Abstract

To provide at least one of a sintered body with improved impact resistance achieved by generating impact absorption through plastic deformation prior to the occurrence of brittle fracture in response to an impact that exceeds the fracture resistance of the sintered body, and a manufacturing method for the sintered body.SOLUTION: A sintered body that comprises zirconia containing a stabilizer and that has an area in which an impact mark is formed when an impact force is applied is provided.SELECTED DRAWING: Figure 8

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 a zirconia ceramic 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, in Patent Document 1, it has been reported that the fracture toughness is improved by dispersing SrAl O 19 in 4 mol% yttria-containing zirconia. Further, in Patent Document 2, it has been reported that by dispersing cubic Sr x NbO3 in zirconia, the fracture toughness is improved and the drop resistance is improved.

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 described in Patent Documents 1 and 2 was a result of improved fracture resistance obtained by improving fracture toughness. In both sintered bodies, when subjected to an impact exceeding the fracture resistance, brittle fracture such as crack formation occurs first, and fracture occurs as this progresses. Thus, the fracture mechanism in all sintered bodies was caused solely by brittle fracture.

[0006] In contrast, the present disclosure aims to provide at least one of the following: a sintered body in which impact resistance is improved by generating impact absorption through plastic deformation prior to the occurrence of brittle fracture in the face of an impact exceeding the fracture resistance of the sintered body, and a method for manufacturing the same. [Means for solving the problem]

[0007] The inventors investigated ways to improve the impact resistance of ceramics. As a result, they found that an improvement in impact resistance could be achieved through a mechanism different from that of improving fracture toughness.

[0008] In other words, the present invention is as described in the claims, and the gist of this disclosure is as follows. [1] A sintered body comprising zirconia containing a stabilizer, and having a region in which an impact mark is formed when an impact force is applied. [2] The sintered body according to [1] above, wherein the impact mark is a recess. [3] The sintered body according to [1] or [2] above, wherein the stabilizer content is 3 mol% or more and 10 mol% or less. [4] The sintered body 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 body according to any one of [1] to [4] above, wherein the stabilizer is yttria and ceria. [6] A sintered body according to any one of [1] to [5] above, wherein the yttria content is less than 1.5 mol%. [7] A 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] A sintered body according to any one of [1] to [7] above, comprising alumina. [9] A sintered body according to any one of [1] to [8] above, having a region in which 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 is greater than 0 and less than or equal to 1.0.

[10] A sintered body according to any one of [1] to [9] above, having a region in which, when an impact force is applied, the intensity of the powder X-ray diffraction peak of the (004) plane of the tetragonal crystal is greater than 1.0 and less than or equal to 10, relative to the intensity of the powder X-ray diffraction peak of the (220) plane of the tetragonal crystal.

[11] A sintered body according to any one of the above [1] to

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

[12] A component comprising the sintered body described in any one of [1] to

[11] above. [Effects of the Invention]

[0009] This disclosure provides at least one of the following: a sintered body in which impact resistance is improved by generating impact absorption through plastic deformation prior to the occurrence of brittle fracture in the face of an impact exceeding the fracture resistance of the sintered body, and a method for manufacturing the same. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing a ball drop test using a DuPont ball drop test machine. [Figure 2] A schematic diagram showing an example of the impact point (formation of a recess) after a ball drop test. [Figure 3] A schematic diagram showing an example of the area near the impact point of a high-hardness sintered body after a ball drop test. [Figure 4] A schematic diagram showing an example of the arrangement of measurement samples in a ball-fall test. [Figure 5] A schematic diagram showing a method for measuring the depth of impact marks. [Figure 6]A schematic diagram showing an example of the type of failure observed in a ball drop test: (a) state where failure has occurred, (b) state where failure has not occurred. [Figure 7] Appearance of the sintered body of Example 1 after the drop test [Figure 8] Appearance of impact marks formed on the sintered body of Example 1 after the drop test (magnified: 20x) [Figure 9] Appearance of the sintered body of Comparative Example 3 after the drop test (magnification: 20x) [Modes for carrying out the invention]

[0011] The sintered body of this disclosure will be described below with reference to an example of an embodiment.

[0012] The sintered body of this embodiment is characterized by containing zirconia containing a stabilizer and having a region in which an impact mark is formed when an impact force is applied.

[0013] The sintered body of this embodiment is preferably a so-called zirconia sintered body, which contains zirconia containing a stabilizer, and more preferably has zirconia containing a stabilizer as the matrix (main phase). Because it contains a stabilizer, the sintered body of this embodiment can also be considered a partially stabilized zirconia sintered body.

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

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

[0016] "Impact force" is a force that transmits energy to a sintered body, and is particularly a dynamic external force, preferably an external force that exceeds the fracture resistance of the sintered body, more preferably a dynamic external force that exceeds the fracture resistance of the sintered body, and even more precisely, 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. Examples include contact between the sintered body and the ground due to falling, or contact between the falling object and the sintered body, in which energy is dynamically applied to the sintered body through contact with the object it is contacted with.

[0018] An "impact mark" is a trace left on a sintered body where an impact force has been applied, preferably a trace formed on the sintered body by the application of an impact force. In other words, an impact mark is a trace left on the sintered body where plastic deformation has occurred, and is a trace left on plastic deformation that occurred prior to fracture. Specific examples of impact marks include recesses, uneven surfaces, recesses, and recesses along the direction in which the impact force was applied, in the impact point (described later).

[0019] In this embodiment, whether or not a sintered body has a plastic deformation region can be confirmed by applying an impact force (for example, a dynamic external force that causes the sintered body to fracture) to the sintered body in any way. By applying an impact force to the sintered body and confirming the formation of impact marks, such as depressions or uneven areas, which are traces of plastic deformation (especially traces of deformation that occurred prior to fracture), it can be confirmed that the sintered body has a plastic deformation region. In the sintered body of this embodiment, the impact marks are formed due to plastic deformation, but may also include defects such as cracks that occur afterward (after the formation of the impact marks). On the other hand, if, after the application of the impact force, only defects such as cracks are present (i.e., only defects are confirmed without the formation of impact marks due to plastic deformation), or if only deformation originating from fracture, such as Hertz fracture, is present (i.e., only deformation formed by the progression of fracture such as the first crack is confirmed; Figure 9, dashed circle), it can be determined that the sintered body does not have a plastic deformation region.

[0020] A preferred method for confirming the existence of a plastic deformation region is to use a DuPont drop ball tester conforming to JIS K 5600 5-3 and drop a 300g weight from a height of 350mm at room temperature (hereinafter also simply referred to as the "drop ball test").

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

[0022] Figure 2 is a schematic diagram showing the appearance of the sintered body of this embodiment after a ball drop test. As shown in Figure 2, it can be confirmed that an impact mark was formed in the region where the impact force from the dropped weight (striking mold) was applied (hereinafter also referred to as the "impact core") of the sintered body of this embodiment during the ball drop test. The impact mark in Figure 2 shows a state in which a recess has been formed near the impact core, and it can be visually confirmed that there is a plastic deformation region. Although not shown, there may be defects such as cracks near the recess. In contrast, Figure 3 is a schematic diagram showing the appearance of a conventional sintered body after a ball drop test. As shown in Figure 3, in the conventional sintered body, the formation of an impact mark in the impact core cannot be confirmed, and only defects such as cracks have occurred.

[0023] The presence or absence of a plastic deformation region can be confirmed by visual inspection and / or observation with an optical microscope, or by visual inspection alone. Examples of observation magnifications for optical microscope observation include 1 to 100 times, preferably 10 to 30 times.

[0024] Although not shown in the diagram, conventional sintered bodies have high fracture toughness (for example, a fracture toughness value of 7 MPa·m measured by the SEPB method). 0.5 For sintered bodies exceeding a certain height, there is no change in appearance before and after the drop test, making it impossible to confirm the impact point. In this case, the drop test can be performed by increasing the drop height until the impact point can be confirmed, and the presence or absence of a plastic deformation region can be confirmed by checking for the formation of impact marks such as recesses and the occurrence of defects at the confirmed impact point. However, in the case of the sintered body of this embodiment, the presence or absence of a plastic deformation region can be confirmed by a drop test at a drop height of 350 mm.

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

[0026] To prevent the sample fragments from scattering, the sample is fixed to the sample stand of the ball-fall test machine and one side of the sample (a 40mm x 30mm surface) using double-sided tape. After positioning, fixing tape (protective tape) is applied along the vertical direction of the main surface opposite to the fixed surface to secure the sample (Figure 4). The ball-fall test can then be performed on the secured sample.

[0027] The depth of the impact marks formed by the ball drop test can be defined as, for example, the depth of the deepest part of the impact mark (Figure 2:204) relative to the thickness of the sintered body (Figure 2:203), being greater than 0 and less than or equal to 3.5, and more specifically, between 0.5 and 3. Note that the depth of the impact mark (recess) (204) in Figure 2 is shown with the depth exaggerated.

[0028] In this embodiment, the depth of the impact mark can be measured using a general-purpose laser microscope (e.g., VK-9500 / VK-9510, manufactured by Keyence Corporation). Examples of observation magnifications include 10 to 50 times, and even 20 times, and a laser wavelength of 408 nm.

[0029] Figure 5 shows a schematic diagram illustrating the method for measuring the depth of an impact mark. The measurement is performed by creating a line profile (503A) that passes through the center of the impact mark and measuring the length of the deepest point (L1) in the Z-axis direction. Similarly, a similar line profile (503B) is created perpendicular to the first line profile and the length of the deepest point (L2) in the Z-axis direction is measured. The lengths of both deepest points obtained are averaged (=(L1+L2) / 2), and this length is taken as the depth of the impact mark (504). An example of a measurement condition for measuring the length of the deepest point is 0.5 μm / step. Prior to measurement, a standard sample attached to the instrument with a known pattern length (e.g., a Si substrate with a pattern engraved on it) should be measured to adjust the accuracy of the analysis.

[0030] Such line profiles and measurements of the deepest point in the Z-axis direction can be performed using image analysis software included with 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 elements that have the function of stabilizing zirconia, and preferably consists of two or more elements selected from the group consisting of yttria (Y2O3), calcia (CaO), magnesia (MgO), and ceria (CeO2). It is more preferably at least yttria, more preferably one or more elements selected from the group consisting of calcia, magnesia, and ceria, and yttria, and even more preferably yttria and ceria.

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

[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 more preferably 1.2 mol% or less. When ceria is present with yttria, it is easier to obtain a sintered body by simple methods such as atmospheric pressure sintering, so the yttria content is preferably greater than 0 mol%, more preferably 0.5 mol% or more, more preferably 0.6 mol% or more, more preferably 0.9 mol% or more, and more preferably 1.0 mol% or more.

[0034] The sintered body of this embodiment only needs to satisfy the above-mentioned stabilizer content, but the ceria content when ceria is included as a stabilizer is arbitrary. Examples of ceria content include 2 mol% to 7.5 mol%, moreover 2.5 mol% to 6 mol%, and moreover 3 mol% to 5 mol%. When calcia is included as a stabilizer, the calcia content can be exemplified as 2 mol% to 7.5 mol%, and moreover 2.5 mol% to 6 mol%, and when magnesia is included as a stabilizer, the magnesia content can be exemplified as 2 mol% to 7.5 mol%, and moreover 2 mol% to 6 mol%.

[0035] The sintered body of this embodiment preferably contains ceria and yttria as stabilizers, in which case the ceria content is preferably 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 preferably 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 oxides to the total of zirconia and the oxide-converted stabilizers. 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 calculated from {(Y2O3 / (Y2O3+ZrO2)) × 100 (mol%). Similarly, the ceria content in ceria-stabilized zirconia is the ratio (mol%) of ceria to the total of zirconia and ceria, and can be calculated from {(CeO2 / (CeO2+ZrO2)) × 100 (mol%). Furthermore, the yttria content in yttria and ceria-stabilized zirconia sintered bodies can be calculated as {Y2O3 / (Y2O3+CeO2+ZrO2)} × 100 (mol%). In this embodiment, ceria is preferably composed of tetravalent cerium and more preferably does not contain trivalent cerium.

[0037] Because impact marks due to plastic deformation tend to occur more easily, 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 the "S / Y ratio," and if the stabilizing agent other than yttrium is cerium (Ce), etc., it is also referred to as the "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, even more preferably 1.5 or more and 2.3 or less, and even more preferably 1.6 or more and 2.0 or less.

[0038] The sintered body of this embodiment may contain alumina (Al2O3). This tends to increase mechanical properties, such as static strength. The sintered body of this embodiment does not have to contain alumina, so the alumina content is 0% by mass or more. If alumina is included, the alumina content is greater than 0% by mass and less than 30% by mass, preferably greater than 0% by mass and 20% by mass or less, and more preferably 0.005% by mass or more and 10% by mass or less. Alternatively, the alumina content may be 0% by mass or more, greater than 0% by mass, 0.5% by mass or more, or 1% by mass or more, and also 20% by mass or less, 17% by mass or less, 12% by mass or less, 10% by mass or less, or 8% by mass or less. The alumina content can be determined as the mass ratio of aluminum (Al2O3 equivalent) to the total amount of zirconia, the stabilizer (oxide equivalent), and the aluminum (Al2O3 equivalent). For example, if zirconia contains yttria and ceria as stabilizers, the alumina content can be calculated as {Al2O3 / (ZrO2+Y2O3+CeO2+Al2O3)} × 100 (mass%).

[0039] Alumina (Al2O3) has a significant impact on the mechanical properties of the sintered body and has almost no effect on coloring zirconia. Therefore, in this embodiment, alumina, i.e., aluminum that does not form a composite oxide with metal elements, is not included in the pigment.

[0040] 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 a 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, more preferably more than 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 can be determined as {(ZrO2 + Y2O3 + CeO2) / (ZrO2 + Y2O3 + CeO2 + Al2O3)}×100 (mass%).

[0041] The sintered body of this embodiment may contain inevitable impurities such as hafnia (HfO2), but preferably does not contain anything other than the stabilizer, zirconia, alumina, and inevitable impurities. In this embodiment, for calculating values affected by the composition such as the content and density of each component, these values may be calculated by regarding hafnia (HfO2) as zirconia (ZrO2).

[0042] The sintered body of this embodiment preferably has a high density, and more preferably has a density corresponding to 98% or more as the 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 3The following conditions must be met. Furthermore, if the alumina content exceeds 10% by mass but is 20% by mass or less, the measured density is 5.30 g / cm³. 3 More than 5.85g / cm 3 If the alumina content is less than 20% by mass but less than 30% by mass, the measured density is 5.20 g / cm³. 3 More than 5.30g / cm 3 One example is being less than [a certain value].

[0043] In this embodiment, the measured density can be determined by the Archimedes method, and is the value obtained as the mass determined by mass measurement in relation to the volume determined by the Archimedes method.

[0044] The crystalline phase of the zirconia in the sintered body of this embodiment preferably includes at least a tetragonal crystal, and may consist of at least one of a tetragonal crystal and a cubic crystal and a monoclinic crystal.

[0045] The sintered body of this embodiment has a 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 referred to as "I (004) / (220) It is preferable that the (220) plane of the tetragonal crystal (hereinafter referred to as "T") has a region where the (T) is greater than 0 and less than or equal to 1.0 (hereinafter also referred to as the "random orientation region"). It is more preferable that it consists of a random orientation region. 220 It is also called "T 004 It is also called ). ) are crystal planes that are 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. (004) / (220) It is preferably 0.1 or more and 0.7 or less, and more preferably 0.2 or more and 0.6 or less.

[0046] When the sintered body of this embodiment absorbs or disperses energy due to 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 (after the application of the impact force), the crystal orientation in the plastic deformation region may increase, and furthermore, when an impact force is applied, T 220 T 004 One characteristic is that it has a region where the intensity of the powder X-ray diffraction peak is greater than 1.0 and less than or equal to 10 (hereinafter also referred to as the "highly oriented region"). (004) / (220) It is preferably 1.5 or more and 8.0 or less, and more preferably 3.0 or more and 5.0 or less.

[0047] In this embodiment, the powder X-ray diffraction pattern (X-ray diffraction pattern) of the sintered body can be measured using a general crystallinity analysis X-ray diffractometer (for example, instrument name: X'pert PRO MPD, manufactured by Spectris).

[0048] The following conditions can be used as measurement conditions. Radiation source: CuKα radiation (λ=1.5405Å) Tube voltage: 45kV Tube current: 40mA High-speed detector: X'Celerator + Ni filter Micro-optical system: Monocapillary, 0.1mm diameter Measurement angle: 70~80° Goniometer: Radius 240mm

[0049] In the above measurement, T 004 The diffraction intensity is defined as the diffraction intensity (area intensity) of the XRD peak with its peak top at 2θ = 72.5 ± 1°, T 220 The diffraction intensity is confirmed as the diffraction intensity (area intensity) of the XRD peak with its peak top at 2θ = 74 ± 1°.

[0050] The shape of the sintered body in this embodiment can be, for example, at least one selected from the group consisting of spherical, substantially spherical, elliptical, disc-shaped, cylindrical, cubic, rectangular parallelepiped, polyhedral, and substantially polyhedral shapes. Furthermore, any shape that achieves the intended purpose, such as various applications, is acceptable.

[0051] The sintered body of this embodiment preferably has a ball impact strength of 1 J or more, more preferably 1.5 J or more. Ball impact strength is one indicator of impact resistance, and the higher this value, the higher the impact resistance. Examples of ball impact strengths for the sintered body include 10 J or less, 5 J or less, or 4 J or less.

[0052] In this embodiment, the ball drop strength is the energy imparted to the sintered body by a falling weight when the weight is dropped from a predetermined height and the sintered body is destroyed. The ball drop strength can be calculated using the following formula, and is preferably the value at a sample thickness of 2 mm.

[0053] Falling ball force (J) = Mass of falling weight (g) × Falling height (mm) × Gravitational acceleration (m / s²) 2 ) The acceleration due to gravity is 9.8 m / s². 2 You can use this.

[0054] The drop strength can be measured using the same method as the drop test described above, except that the drop height is set to any of the heights shown below. Falling ball height: 50-500mm

[0055] Fracture can be determined when the sample is divided into two or more parts (Figure 6(a)). On the other hand, if a crack occurs that does not reach from one end to the other (Figure 6(b)), it can be considered that no fracture has occurred. If no fracture occurs in a drop test at a specific drop height, the drop test can be repeated by increasing the drop height in 50 mm increments up to 500 mm until fracture occurs, and visual observation can be performed in the same manner. In this embodiment, for samples in which no fracture occurred in a drop test at a drop height of 500 mm, the drop strength can be conveniently set to >5 J (greater than 5 J).

[0056] In this embodiment, it is preferable that the sintered body exhibits improved impact resistance due to plastic deformation rather than improved hardness. Because plastic deformation tends to occur more easily, the Vickers hardness (Hv) of the sintered body in this embodiment is preferably 12 GPa or less, more preferably 11 GPa or less, and even more preferably 10 GPa or less.

[0057] In this embodiment, Vickers hardness can be measured by a method conforming to JIS R1610:2003. The following conditions are examples of conditions for measuring Vickers hardness. Measurement sample: (Sample thickness) 1.5±0.5mm (Measured surface roughness) Ra ≤ 0.02 μm Measured load: 10 kgf

[0058] The measurement can be performed using a standard Vickers hardness tester equipped with a diamond square pyramidal indenter (e.g., MV-1, manufactured by Matsuzawa Co., Ltd.). The measurement involves statically pressing the indenter into the surface of the sample and visually measuring the diagonal length of the indentation formed on the sample surface. Using the obtained diagonal length, the Vickers hardness can be calculated using the following formula. Hv=F / {d 2 / 2sin(α / 2)}

[0059] In the above equation, Hv is the Vickers hardness (GPa), F is the measured load (10 kgf), d is the diagonal length of the indentation (mm), and α is the angle of the indenter (136°).

[0060] In this embodiment, the fracture toughness value can be used as an indicator of the fracture resistance of the sintered body. The fracture toughness value is the value of fracture toughness (MPa·m) measured by a method conforming to the SEPB method specified in JIS R 1607. 0.5The fracture toughness value is measured using a columnar sintered body sample with a width of 4 mm and a thickness of 3 mm, with a support distance of 30 mm, and the average value of 10 measurements is taken as the fracture toughness value of the sintered body in this embodiment. Note that JIS R 1607 specifies two methods for measuring fracture toughness: the IF method and the SEPB method. The IF method is a simple measurement method, so there is a large variation in the measured values ​​from one measurement to the next. Therefore, the absolute values ​​of the fracture toughness value in this embodiment and the fracture toughness value measured by the IF method cannot be compared.

[0061] The color tone of the sintered body in this embodiment is arbitrary, but CIE1976(L * a * b * ) Brightness L in the color space * Examples include values ​​of 80 or higher, even 85 or higher, and even 90 or higher. * The upper limit is 100 or less.

[0062] Lightness L * This can be measured using a general spectrophotometer (e.g., CM-700d, manufactured by Konica Minolta) in accordance with JIS Z8722. * The following conditions are suggested for measurement. It is preferable to perform the measurement using a black board as the background (so-called black background measurement). Light source: F2 light source Viewing angle: 10° Measurement method: SCI

[0063] For measurement, a disc-shaped sintered body with a diameter of 20 mm and a thickness of 2.7 mm should be used. The surface to be evaluated should be mirror-polished (Ra ≤ 0.02 μm), and the color tone should be evaluated. A diameter of 10 mm is suggested as an effective area for color tone evaluation.

[0064] The sintered body of this embodiment, in particular, a sintered body that does not contain pigment, has the above-mentioned brightness L * It is preferable that it has a saturation a * and b * It tends to become smaller. For example, the chroma a of the sintered body of this embodiment* and b * These are -6≦a * ≤ -2, and 10 ≤ b * One example is that the value is ≤30.

[0065] The sintered body of this embodiment can be used in applications of conventional sintered bodies, particularly zirconia sintered bodies used for structural materials, optical materials, dental materials, etc., but it can also be used as a component requiring relatively high impact resistance, such as for decorative items, covers for accessories such as watches and casings, and exterior components for portable electronic devices such as mobile phones.

[0066] Further preferred embodiments include the following: (1) A sintered body containing one or more stabilizers selected from the group consisting of calcia, magnesia and ceria, and yttria, with the remainder being zirconia, wherein the stabilizer content is 2 mol% or more and 7.5 mol% or less, the yttria content is greater than 0 mol% and less than 1.5 mol%, and furthermore, the region having a region in which the intensity of the powder X-ray diffraction peak of the (004) plane of a tetragonal crystal is greater than 0 and 1.0 or less, relative to the intensity of the powder X-ray diffraction peak of the (220) plane of a tetragonal crystal. (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 is 4 mol% or more and 7.5 mol% or less. (4) The sintered body according to any one of (1) to (3) above, wherein the sintered body comprises a region in which the intensity of the powder X-ray diffraction peak of the (004) plane of the tetragonal crystal is greater than 0 and less than or equal to 1.0, relative to the intensity of the powder X-ray diffraction peak of the (220) plane of the tetragonal crystal. <Other Embodiments> Another embodiment of the present disclosure is a sintered body characterized by having a region in which an impact mark is formed when an impact force is applied.

[0067] Another embodiment of the present disclosure is a sintered body characterized by the formation of impact marks when an impact force is applied.

[0068] Another embodiment of the present disclosure is a sintered body characterized by forming a recess by a drop ball test using a DuPont drop ball tester conforming to JIS K 5600 5-3, in which a 300g drop weight is dropped from a height of 350mm at room temperature.

[0069] Another embodiment of the present disclosure is a sintered body having a region in which the intensity of the powder X-ray diffraction peak of the (004) plane of a tetragonal structure is greater than 0 and less than or equal to 1.0 relative to the intensity of the powder X-ray diffraction peak of the (220) plane of a tetragonal structure, and after an impact force is applied, having a region in which the intensity of the powder X-ray diffraction peak of the (004) plane of a tetragonal structure is greater than 1.0 and less than or equal to 10 relative to the intensity of the powder X-ray diffraction peak of the (220) plane of a tetragonal structure.

[0070] In these embodiments, the sintered body is preferably a zirconia sintered body, more preferably a partially stabilized zirconia sintered body, even more preferably an yttria and ceria stabilized zirconia sintered body, and even more preferably an yttria and ceria stabilized zirconia sintered body having an yttria content of 1.0 mol% or more and less than 1.5 mol%.

[0071] The following describes the method for manufacturing the sintered body according to this embodiment.

[0072] The manufacturing method for the sintered body of this embodiment is arbitrary, as long as a sintered body that satisfies the above requirements can be obtained. As an example of a manufacturing method for the sintered body of this embodiment, a manufacturing method can be exemplified that includes a step of sintering a molded body containing two or more stabilizing agent sources and zirconia.

[0073] The molded body subjected to the above process (hereinafter also referred to as the "sintering process") is a molded body (compacted body) containing two or more stabilizing agent sources and zirconia.

[0074] The stabilizer source only needs to contain elements that become stabilizers through sintering, and may be a compound containing yttria, calcia, magnesia, and ceria, or one or more elements selected from the group of yttrium (Y), calcium (Ca), magnesium (Mg), and cerium (Ce), which are precursors thereof (hereinafter, the stabilizer source when the stabilizer is yttria will also be referred to as the "yttria source," etc.). The stabilizer source is preferably a compound containing at least one of the elements yttria and ceria, or yttrium and cerium, which are precursors thereof, and more preferably at least one compound containing yttria and yttrium, and at least one compound containing ceria and cerium.

[0075] The yttria source may be at least one of yttria and yttria compounds that are precursors thereof, and may be one or more selected from the group consisting of yttria chloride, yttria, and yttria carbonate, with yttria being preferred.

[0076] The ceria source may be at least one of ceria and a cerium compound that is a precursor thereto, and may be one or more selected from the group consisting of cerium chloride, ceria, and cerium carbonate, with cerium chloride being preferred.

[0077] The calcia source may be at least one of calcia and calcium compounds that are precursors thereof, and may be one or more selected from the group consisting of calcium chloride, calcia, calcium carbonate, and calcium bicarbonate, with calcia being preferred.

[0078] The magnesia source may be at least one of magnesia and magnesium compounds that are precursors thereof, and may be one or more selected from the group consisting of magnesium chloride, magnesia, magnesium carbonate, and magnesium bicarbonate, with magnesia being preferred.

[0079] The content of the stabilizer source in the molded body should be equivalent to the content of the stabilizer in the target sintered body.

[0080] When a sintered body containing alumina is used, the molded body may contain an alumina source. The alumina source is at least one of a compound containing alumina (Al2O3) and its precursor, aluminum (Al), and includes one or more selected from the group consisting of aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum hydroxide, and alumina, with alumina being preferred.

[0081] The alumina source content in the molded body should be equivalent to the alumina content of the target sintered body.

[0082] To improve shape stability, the molded body may contain a binder. The binder can be any organic binder used for molding ceramics, such as one or more selected from the group consisting of acrylic resin, polyolefin resin, wax, and plasticizer. An example of the binder content is 25 to 65% by volume, as the proportion of the binder to the volume of the molded body.

[0083] The shape of the molded body can be any shape appropriate to the purpose, taking into account shrinkage due to sintering. Examples include at least one selected from the group consisting of spherical, nearly spherical, elliptical, disc-shaped, cylindrical, cubic, rectangular, polyhedral, and nearly polyhedral shapes.

[0084] The method for manufacturing the molded article is arbitrary and may include mixing and molding zirconia, a stabilizer source, and, if necessary, an alumina source, in any manner. Alternatively, stabilizer-containing zirconia may be used instead of, or in addition to, zirconia and a stabilizer source.

[0085] When using stabilizer-containing zirconia as the material, the method of incorporating the stabilizer into the zirconia is arbitrary. For example, this can be done by mixing hydrated zirconia sol with a stabilizer source equivalent to the desired stabilizer content, followed by drying, calcination, and washing with water.

[0086] 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.

[0087] The molding method may be any known molding method, preferably at least one selected from the group consisting of uniaxial compression molding, isotropic compression molding, injection molding, extrusion molding, rolling granulation, and casting molding; more preferably at least one of uniaxial compression molding and isotropic compression molding; and even more preferably at least one of cold isostatic pressing and uniaxial compression molding (powder press molding).

[0088] The sintering process involves sintering the molded body to obtain a sintered body. The sintering method is arbitrary and can be atmospheric pressure sintering or pressurized sintering. Examples of known sintering methods include sintering and vacuum sintering. A preferred sintering method is atmospheric pressure sintering, and because it is simple, it is preferable that the sintering method be atmospheric pressure sintering only. This allows the sintered body of this embodiment to be obtained as a so-called atmospheric pressure sintered body. Atmospheric pressure sintering is a method of sintering by simply heating the molded body (or calcined body) without applying any external force during sintering.

[0089] Examples of conditions for atmospheric pressure sintering include a sintering temperature of 1250°C to 1600°C, preferably 1300°C to 1580°C, or 1300°C to 1560°C. Furthermore, the sintering atmosphere can be at least one of an air atmosphere and an oxygen atmosphere, with an air atmosphere being preferred. This ensures that, when ceria is included as a stabilizer, the ceria contains tetravalent cerium (Ce). 4+ ) consists of. [Examples]

[0090] The embodiment will be described in detail below with reference to examples. However, this embodiment is not limited to these examples. (Confirmation of the plastic deformation region) The presence or absence of a plastic deformation region in the sintered body sample was confirmed by a ball-dropping test using a DuPont type ball-dropping test machine (device name: H-50, manufactured by Toyo Seiki Co., Ltd.) conforming to JIS K 5600 5-3. The test conditions are shown below. Dropping weight: (Shape) A spherical rigid ball with a diameter of 6.35 mm, i.e., a cylindrical mold with a height of 10 mm and a spherical tip with a diameter of 6.35 mm. (Mass) 300g, that is, a 300g weight made of stainless steel, in the shape of a rectangular prism measuring 80mm wide x 20mm thick x 30mm high. Drop height: 350mm Measurement sample: A sintered body in the shape of a plate measuring 40 mm (length) x 30 mm (width) x 2 mm (thickness), with a surface roughness of Ra ≤ 0.02 μm on both surfaces (the 40 mm x 30 mm surface; the main surface). To prevent the sample fragments from scattering, the sample was fixed to the sample stand of the ball-fall test machine and one surface of the sample (a 40mm x 30mm surface) using double-sided tape. After positioning, tape was applied along the vertical direction of the surface opposite the fixed surface of the sample to secure it. The ball-fall test was then conducted by positioning the drop weight so that it fell near the center of the secured sample.

[0091] (Measurement of ball drop strength) Aside from changing the height of the falling ball, the falling ball strength was measured using the same method as in the falling ball test used to confirm the plastic deformation region. Specifically, the condition of the sample after dropping the weight was visually inspected, and the falling ball strength at the height at which fracture occurred in the sample was calculated using the following formula. Falling ball force (J) = Mass of falling weight (g) × Falling height (mm) × Gravitational acceleration (9.8 m / s²) 2 )

[0092] Fracture was determined when the sample was broken into two or more pieces. However, extremely small fragments, such as chipping, that formed while the sample maintained a plate-like shape were not considered fracture. If no fracture occurred in a drop test at a specific drop height, the drop test was repeated by increasing the drop height in 50mm increments up to 500mm until fracture occurred. For samples that did not fracture in the 500mm drop test, the drop strength was conveniently defined as >5J (greater than 5J). (Depth of impact marks) The depth of the impact mark was measured using a standard laser microscope (device name: VK-9500 / VK-9510, manufactured by Keyence Corporation) at a magnification of 20x. A line profile was created passing through the center of the impact mark, and the length of the deepest point (L1) was measured in the Z-axis direction at a step of 0.5 μm. Then, a line profile was created orthogonally to the first line profile using the same method, and the length of the deepest point (L2) in the Z-axis direction was measured. The lengths of both deepest points obtained were averaged (=(L1+L2) / 2), and the resulting length was taken as the depth of the impact mark. (Vickers hardness) Vickers hardness was measured using a standard Vickers testing machine (device name: MV-1, manufactured by Matsuzawa Co., Ltd.) equipped with a diamond square pyramidal indenter.

[0093] The indenter was statically pressed into the surface of the sample, and the diagonal length of the indentation formed on the sample surface was measured visually. Using the obtained diagonal length, the Vickers hardness (GPa) was calculated from the formula described above. (density) The measured density of a sintered body sample is the ratio of the volume measured by the Archimedes method to the mass measured by mass dating (g / cm³). 3 ) was calculated as follows. (I (004) / (220) ) Crystalline phase of sintered body sample, T 004 and T 220 The diffraction intensity was measured using micro-XRD (instrument name: X'pert PRO MPD, manufactured by Spectris). The measurement conditions are described below. Radiation source: CuKα radiation (λ=1.5405Å) Tube voltage: 45kV Tube current: 40mA High-speed detector: X'Celerator + Ni filter Micro-optical system: Monocapillary, 0.1mm diameter Measurement angle: 70~80° Goniometer: Radius 240mm

[0094] Micro-area XRD measurements were performed on the impact point and areas other than the impact point of the measurement sample before the test and after confirmation of the plastic deformation region. (004) / (220) The value was calculated according to the following formula. I (004) / (220) =(T 004 (Diffraction intensity of) / (T 220 Diffraction strength (degrees)

[0095] (Color measurement) The color tone of the sintered body sample was measured according to the method compliant with JIS Z8722. A spectrophotometer (device name: CM-700d, manufactured by Konica Minolta) was used, and measurements were taken against a black background with a black board behind it. The measurement conditions were as follows: Light source: F2 light source Viewing angle: 10° Measurement method: SCI

[0096] A sintered body sample in the shape of a disc 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 set to a diameter of 10 mm.

[0097] Example 1 A hydrolysis reaction of an aqueous solution of zirconium oxychloride yielded a hydrated zirconia sol. Yttria and cerium chloride heptahydrate were added to and mixed with hydrated zirconia sol so that the yttria concentration was 1.1 mol% and the ceria concentration was 3.4 mol%, respectively. After mixing, the mixture was dried in the air and calcined in the air at 1155°C for 2 hours to obtain calcined yttria-ceria stabilized zirconia powder. The obtained calcined powder was washed with pure water and dried to obtain zirconia powder consisting of yttria and ceria stabilized zirconia with an yttria content of 1.1 mol% and a ceria content of 3.4 mol%.

[0098] The obtained powder and α-alumina powder with an alumina content of 5% by mass were added to pure water to form a slurry, which was then ground and mixed for 18 hours in a ball mill using 10 mm diameter zirconia balls as the grinding medium. The slurry after grinding and mixing was dried to obtain the zirconia powder of this example, which consists of yttria and ceria-stabilized zirconia containing 5% by mass of alumina and the remainder being yttria content of 1.1 mol% and ceria content of 3.4 mol%.

[0099] The obtained powder was granulated to form powder granules, which were then filled into a plate-shaped mold measuring 40 mm in length and 30 mm in width. Uniaxial pressing at a molding pressure of 50 MPa and cold isostatic pressing (CIP) at a molding pressure of 196 MPa were performed to obtain a plate-shaped molded body (compacted powder). The obtained molded body was sintered under the following conditions to obtain the sintered body of this example, which consists of yttria-ceria stabilized zirconia containing 5% by mass of alumina and the remainder being 1.1 mol% yttria and 3.4 mol% ceria. The sintering conditions are shown below. Sintering method: Atmospheric pressure sintering Sintering atmosphere: Atmospheric atmosphere Sintering temperature: 1550℃ Sintering time: 2 hours

[0100] Example 2 Except for adding and mixing cerium chloride heptahydrate to the hydrated zirconia sol so that the ceria concentration was 3.9 mol%, a zirconia powder of this example was obtained in the same manner as in Example 1, consisting of yttria-ceria stabilized zirconia containing 5% by mass of alumina, with the remainder being yttria content of 1.1 mol% and ceria content of 3.9 mol%.

[0101] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder being yttria-ceria stabilized zirconia containing 5% by mass of alumina and 1.1 mol% yttria and 3.9 mol% ceria.

[0102] Example 3 Except for adding and mixing cerium chloride heptahydrate to the hydrated zirconia sol so that the ceria concentration was 5.0 mol%, the zirconia powder of this example was obtained in the same manner as in Example 1, consisting of yttria-ceria stabilized zirconia containing 5% by mass of alumina, with the remainder being yttria content of 1.1 mol% and ceria content of 5.0 mol%.

[0103] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina and 1.1 mol% yttria and 5.0 mol% ceria.

[0104] Example 4 Except for adding and mixing yttria and cerium chloride heptahydrate to a hydrated zirconia sol so that the yttria concentration was 0.7 mol% and the ceria concentration was 5.0 mol%, respectively, in the same manner as in Example 1, a zirconia powder of this example was obtained, consisting of yttria-ceria stabilized zirconia containing 5% by mass of alumina, with the remainder being yttria content 0.7 mol% and ceria content 5.0 mol%.

[0105] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina and 0.7 mol% yttria and 5.0 mol% ceria.

[0106] Example 5 Except for adding and mixing yttria and cerium chloride heptahydrate to a hydrated zirconia sol so that the yttria concentration was 1.0 mol% and the ceria concentration was 3.6 mol%, respectively, in the same manner as in Example 1, a zirconia powder of this example was obtained, consisting of yttria-ceria stabilized zirconia containing 5% by mass of alumina, with the remainder being yttria content 1.0 mol% and ceria content 3.6 mol%.

[0107] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina and 1.0 mol% yttria and 3.6 mol% ceria.

[0108] Comparative Example 1 The zirconia powder of this comparative example was obtained in the same manner as in Example 1, except that yttria was added to and mixed with hydrated zirconia sol so that the yttria concentration was 1.5 mol%, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina, with the remainder being 1.5 mol% yttria and 3.4 mol% ceria.

[0109] A sintered body of this comparative example was obtained in the same manner as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina and the remainder being 1.5 mol% yttria and 3.4 mol% ceria.

[0110] Comparative Example 2 Except for adding and mixing yttria and cerium chloride heptahydrate to a hydrated zirconia sol so that the yttria concentration was 2.0 mol% and the ceria concentration was 3.9 mol%, respectively, the zirconia powder of this comparative example was obtained in the same manner as in Example 1, consisting of yttria / ceria-stabilized zirconia containing 5% by mass of alumina, with the remainder being yttria content 2.0 mol% and ceria content 3.9 mol%.

[0111] A sintered body of this comparative example was obtained in the same manner as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina and the remainder being yttria content of 2.0 mol% and ceria content of 3.9 mol%.

[0112] Comparative Example 3 Except for adding and mixing yttria and cerium chloride heptahydrate to a hydrated zirconia sol so that the yttria concentration was 3.0 mol% and the ceria concentration was 3.9 mol%, respectively, the zirconia powder of this comparative example was obtained in the same manner as in Example 1, consisting of yttria / ceria-stabilized zirconia containing 5% by mass of alumina, with the remainder being yttria content 3.0 mol% and ceria content 3.9 mol%.

[0113] A sintered body of this comparative example was obtained in the same manner as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 5% by mass of alumina and 3.0 mol% yttria and 3.9 mol% ceria.

[0114] Comparative Example 4 The zirconia powder of this comparative example was obtained in the same manner as in Example 1, except that yttria was not added to the hydrated zirconia sol, and the remainder consisted of ceria-stabilized zirconia containing 5% by mass of alumina and a ceria content of 3.4 mol%.

[0115] A sintered body of this comparative example was obtained in the same manner as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of ceria-stabilized zirconia containing 5% by mass of alumina and a ceria content of 3.9 mol%.

[0116] Comparative Example 5 Except for adding and mixing yttria to the hydrated zirconia sol so that the yttria concentration was 3.0 mol%, and cerium chloride heptahydrate and α-alumina powder were not used, the zirconia powder of this comparative example, consisting of yttria-stabilized zirconia with an yttria content of 3.0 mol%, was obtained in the same manner as in Example 1.

[0117] A sintered body of this comparative example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used and the sintering temperature was set to 1500°C, and consisting of yttria-stabilized zirconia with an yttria content of 3.0 mol%.

[0118] The results of the above examples and comparative examples are shown in the table below.

[0119] [Table 1]

[0120] In the table above, the "Formation of impact marks" column is marked with "○" for cases where impact marks were observed after the ball drop test, and the column for cases where impact marks were not observed is marked with "×". Figure 7 shows the appearance of the sintered body of Example 1 after the ball drop test. From Figure 7, it can be seen that the area in contact with the dropped weight during the ball drop test formed an impact mark (recess) without fracture such as cracks, that is, an impact mark (recess) as a trace of plastic deformation was observed. Figure 8 shows the appearance of the impact mark magnified (magnification: 20x) as observed with an optical microscope. The impact mark was a circular recess with a diameter of about 2.8 mm, and the depth of the impact mark (recess) relative to the thickness of the sintered body was 2.5. Furthermore, Examples 1 to 5, which had an yttria content of 0.7 mol% or more and less than 1.5 mol%, were all sintered bodies with a tetragonal crystal phase and a zirconia content of 95 mass%, and had a density corresponding to a relative density of 98% or more. Visual inspection of these sintered bodies revealed impact marks similar to those in Figure 7, indicating plastic deformation. In Examples 1 to 5, no effect of ceria content on impact mark formation was observed. However, regardless of ceria content, all sintered bodies in these examples were confirmed to have a drop ball strength of 1 J or more.

[0121] Figure 9 shows the appearance of the sintered body of Comparative Example 3 after the ball drop test, as observed under an optical microscope (magnification: 20x). In Comparative Example 3, cracks propagated due to Hertz fracture without forming impact marks due to plastic deformation, and it can be observed that the sintered body was destroyed as a result. On the other hand, in the sintered body with an yttria content of 1.5 mol% or more, no impact marks were observed, and it was confirmed that the impact resistance was extremely low, with a ball drop strength of 0.4 J or less. Furthermore, in Comparative Example 4, which did not contain yttria, defects such as cracks occurred during sintering, and no measurable sintered body was obtained. In addition, from Comparative Example 5, it was confirmed that the sintered body with only yttria as a stabilizer did not have a plastic deformation region.

[0122] The sintered body of Example 1 had a surface I before the drop test. (004) / (220) and I other than the impact point (004) / (220) While the value was 0.55, the I of the impact point after the ball drop test (004) / (220)The value was 3.43. From this, it can be seen that the ball drop test creates regions in the sintered body with different crystal orientations.

[0123] Furthermore, the sintered bodies of Examples 1 to 6 all exhibit similar color tones. For example, the sintered body of Example 1 is L * =92.41, a * = -3.89 and b * =16.01, and the sintered body of Example 4 is L * =93.21, a * = -3.18 and b * The result was 18.38.

[0124] Example 6 Except for adding and mixing cerium chloride heptahydrate to the hydrated zirconia sol so that the ceria concentration was 3.9 mol%, and using a slurry instead of α-alumina powder, the zirconia powder of this example, consisting of yttria-ceria stabilized zirconia with an yttria content of 1.1 mol% and a ceria content of 3.9 mol%, was obtained in the same manner as in Example 1.

[0125] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia with an yttria content of 1.1 mol% and a ceria content of 3.9 mol%.

[0126] Example 7 Except for adding and mixing cerium chloride heptahydrate to the hydrated zirconia sol so that the ceria concentration was 3.9 mol%, and adding α-alumina powder to form a slurry so that the alumina content was 1% by mass, a zirconia powder of this example was obtained using the same method as in Example 1, wherein the zirconia powder of this example consists of yttria-ceria stabilized zirconia containing 1% by mass of alumina, with the remainder being yttria content of 1.1 mol% and ceria content of 3.9 mol%.

[0127] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 1% by mass of alumina and 1.1 mol% yttria and 3.9 mol% ceria.

[0128] Example 8 Except for adding and mixing cerium chloride heptahydrate to the hydrated zirconia sol so that the ceria concentration was 3.9 mol%, and adding α-alumina powder to form a slurry so that the alumina content was 3% by mass, a zirconia powder of this example was obtained using the same method as in Example 1, wherein the alumina powder contained 3% by mass, and the remainder consisted of yttria / ceria-stabilized zirconia with an yttria content of 1.1 mol% and a ceria content of 3.9 mol%.

[0129] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder being yttria-ceria stabilized zirconia containing 3% by mass of alumina and 1.1 mol% yttria and 3.9 mol% ceria.

[0130] Example 9 Except for adding and mixing cerium chloride heptahydrate to the hydrated zirconia sol so that the ceria concentration was 3.9 mol%, and adding α-alumina powder to form a slurry so that the alumina content was 7% by mass, a zirconia powder of this example was obtained using the same method as in Example 1, wherein the zirconia powder of this example consists of yttria-ceria stabilized zirconia containing 7% by mass of alumina, with the remainder being 1.1 mol% yttria and 3.9 mol% ceria.

[0131] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 7% by mass of alumina and the remainder being 1.1 mol% yttria and 3.9 mol% ceria.

[0132] Example 10 Except for adding α-alumina powder to form a slurry so that the alumina content was 10% by mass, the zirconia powder of this example was obtained in the same manner as in Example 1, consisting of yttria / ceria-stabilized zirconia containing 10% by mass of alumina and the remainder being yttria content of 1.1 mol% and ceria content of 3.4 mol%.

[0133] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder being yttria-ceria stabilized zirconia containing 10% by mass of alumina and 1.1 mol% yttria and 3.4 mol% ceria.

[0134] Example 11 α-alumina powder is added to the slurry so that the alumina content is 16.4% by mass. Except for the use of Lee, the zirconia powder of this example was obtained in the same manner as in Example 1, with the exception of being yttria-ceria stabilized zirconia containing 16.4% by mass of alumina and the remainder consisting of 1.1 mol% yttria and 3.4 mol% ceria.

[0135] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia containing 16.4% by mass of alumina and 1.1 mol% yttria and 3.4 mol% ceria.

[0136] The results of the above examples are shown in the table below.

[0137] [Table 2]

[0138] From the table above, it can be seen that the sintered bodies of these examples have a density equivalent to 98% or more in terms of relative density, and that impact marks are formed regardless of the presence or absence of alumina content and its content. Furthermore, it can be seen that a plastic deformation region exists when the zirconia content is in the range of 83.6% to 100% by mass. In the sintered body of Example 6, the depth of the impact point relative to the sintered body thickness was 2.6. It can also be seen that the Vickers hardness tends to increase with increasing alumina content.

[0139] The sintered bodies of Examples 6 to 11 all exhibit similar color tones, and the color tone is, for example, that of the sintered body of Example 6 is L * =83.98, a * = -4.69 and b * =20.00, the sintered body of Example 9 is L * =94.38, a * = -3.64 and b * =14.13, and the sintered body of Example 10 is L * =95.26, a * = -3.45 and b * The result was 14.22.

[0140] Example 12 The sintered body of this example was obtained in the same manner as in Example 6, except that the sintering temperature was set to 1450°C.

[0141] Example 13 The sintered body of this example was obtained in the same manner as in Example 7, except that the sintering temperature was set to 1450°C.

[0142] Example 14 The sintered body of this example was obtained in the same manner as in Example 8, except that the sintering temperature was set to 1450°C.

[0143] Example 15 The sintered body of this example was obtained in the same manner as in Example 2, except that the sintering temperature was set to 1450°C.

[0144] Example 16 The sintered body of this example was obtained in the same manner as in Example 9, except that the sintering temperature was set to 1450°C.

[0145] The results of the above examples are shown in the table below.

[0146] [Table 3]

[0147] Table 2 and the table above show that even atmospheric pressure sintered bodies obtained at higher sintering temperatures have a density equivalent to 98% or more in terms of relative density and possess a plastic deformation region. Furthermore, it can be confirmed that there is a tendency for hardness to increase and drop strength to decrease as the sintering temperature decreases.

[0148] The sintered bodies of Examples 12 to 16 all exhibit similar color tones, and the color tone is, for example, that of the sintered body of Example 12 is L * =83.52, a * = -4.75 and b * =24.35, the sintered body of Example 15 is L * =94.18, a * = -3.93 and b * The result was 16.79.

[0149] Example 17 Except for adding and mixing yttria and cerium chloride heptahydrate to the hydrated zirconia sol so that the yttria concentration was 1.2 mol% and the ceria concentration was 3.6 mol%, respectively, and α-alumina powder was not used, the zirconia powder of this example, consisting of yttria-ceria stabilized zirconia with an yttria content of 1.2 mol% and a ceria content of 3.6 mol%, was obtained in the same manner as in Example 1.

[0150] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia with an yttria content of 1.2 mol% and a ceria content of 3.6 mol%.

[0151] Example 18 Except for adding and mixing yttria and cerium chloride heptahydrate to a hydrated zirconia sol so that the yttria concentration was 1.0 mol% and the ceria concentration was 4.0 mol%, respectively, and α-alumina powder was not used, the zirconia powder of this example, consisting of yttria-ceria stabilized zirconia with an yttria content of 1.0 mol% and a ceria content of 4.0 mol%, was obtained in the same manner as in Example 1.

[0152] A sintered body of this example was obtained using the same method as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria-ceria stabilized zirconia with an yttria content of 1.0 mol% and a ceria content of 4.0 mol%.

[0153] Comparative Example 6 Except for adding and mixing yttria and cerium chloride heptahydrate to a hydrated zirconia sol so that the yttria concentration was 3.0 mol% and the ceria concentration was 3.9 mol%, respectively, and α-alumina powder was not used, the zirconia powder of this comparative example, consisting of yttria / ceria-stabilized zirconia with an yttria content of 3.0 mol% and a ceria content of 3.9 mol%, was obtained in the same manner as in Example 1.

[0154] A sintered body of this comparative example was obtained in the same manner as in Example 1, except that the obtained zirconia powder was used, and the remainder consisted of yttria / ceria-stabilized zirconia with an yttria content of 3.0 mol% and a ceria content of 3.9 mol%.

[0155] The results for the examples and comparative examples are shown in the table below.

[0156] [Table 4]

[0157] From Examples 17 and 18, and from Example 12, it can be confirmed that even sintered bodies made of yttria and ceria-stabilized zirconia, which do not contain alumina, have a plastic deformation region. On the other hand, the sintered body of Comparative Example 6, despite having a lower ceria content than Example 18, did not have a plastic deformation region, and the surface I before the drop test showed (004) / (220) and I other than the impact point (004) / (220) The value is 0.38, and the I of the impact point after the drop test. (004) / (220) The value is 0.80, and the I test was performed by a dropped ball test. (004) / (220) No significant changes were observed. [Explanation of symbols]

[0158] 100: External view showing an overview of the ball drop test. 101: Sintered body 102: Punching die 103a, 103b: Guide 104: Falling weight 105: Fixing tape 106: Sample stage of the ball-falling test machine 107: Protective tape 200: Sintered body of this embodiment after drop test 201: Sintered body 202: Impact mark (indentation) 203: Depth of impact marks (indentations) 300: Conventional sintered body after drop test 301: Sintered body 302: Defect (crack) 400: Diagram showing the state of the sintered body being placed on the sample stage of the drop test machine. 401: Sintered body 402: Fixing tape 403: Sample stand for the ball-falling test machine 404: Double-sided tape (protective tape) 500: Diagram showing the method for measuring impact mark depth. 501: Sintered body 502: Impact mark (indentation) 503A,B: Line Profile 504: Depth of the deepest part (L1 or L2) 601: Sintered body in a divided state 602: Defect (crack) 702: Impact mark (indentation)

Claims

1. A sintered body comprising one or more stabilizers selected from the group consisting of calcia, magnesia, and ceria, and zirconia containing yttria, wherein the yttria content is less than 1.5 mol%, the ratio (molar ratio) of stabilizers other than yttria to yttria is 1.2 or more and 5.0 or less, and further having a region in which an impact mark is formed when an impact force is applied, wherein in the region in which an impact force is applied, the intensity of the powder X-ray diffraction peak of the (004) plane of the tetragonal crystal is greater than 1.0 and less than or equal to 10 compared to the intensity of the powder X-ray diffraction peak of the (220) plane of the tetragonal crystal.

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

3. The sintered body according to claim 1 or 2, wherein the stabilizer content is 3 mol% or more and 10 mol% or less.

4. The sintered body according to claim 1 or 2, wherein the stabilizer content is 4.2 mol% or more and 6.2 mol% or less.

5. The sintered body according to any one of claims 1 to 4, wherein the stabilizing agent is yttria and ceria.

6. A sintered body according to any one of claims 1 to 5, wherein the yttria content is 1.3 mol% or less.

7. A sintered body according to any one of claims 1 to 6, wherein the ceria content is 2 mol% or more and 7.5 mol% or less.

8. A sintered body according to any one of claims 1 to 7, comprising alumina.

9. A sintered body according to any one of claims 5 to 8, wherein the ratio (molar ratio) of stabilizing elements other than yttrium to yttrium is 1.4 or more and 4.5 or less.

10. CIE1976 (L ＊ a ＊ b ＊ ) Brightness L in the color space ＊ A sintered body according to any one of claims 1 to 9, wherein the ratio is 80 or more.

11. A sintered body according to any one of claims 1 to 8, wherein the Vickers hardness is 12 GPa or less.

12. A member comprising a sintered body according to any one of claims 1 to 11.

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