Ceramic powder, ceramic sintered body, and method of healing ceramic sintered body

Abstract

To provide ceramic powder capable of yielding a ceramic sintered body exhibiting self-healing function at a lower temperature.SOLUTION: The ceramic powder includes zirconium carbide and partially stabilized zirconia, in which the mean particle size of the zirconium carbide is 1 μm or less, the mean particle size of the partially stabilized zirconia is 1 μm or less, the content of the zirconium carbide is 15 vol% or more and 40 vol% or less, and the content of the partially stabilized zirconia is 60 vol% or more and 85 vol% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to ceramic powders, ceramic sintered bodies, and a method for healing ceramic sintered bodies.

Background Art

[0002] Conventionally, oxidation-induced self-healing ceramics have been known. In oxidation-induced self-healing ceramics, a non-oxide (hereinafter also referred to as a healing agent) that is highly active with respect to oxidation in a high-temperature atmosphere is dispersed in a ceramic base material. In oxidation-induced self-healing ceramics, triggered by crack generation during use, the healing agent oxidizes with oxygen in the atmosphere existing outside under high-temperature conditions, and the oxide generated thereby automatically fills and joins the cracks, restoring the strength.

[0003] Patent Document 1 discloses an oxidation-induced self-healing ceramic composition including a ceramic base material, a healing agent of an oxidation-active non-oxide dispersed in the base material, and a healing activator, wherein the healing agent is a substance that generates an oxide by contact with external oxygen due to crack generation in the ceramic composition, and the healing activator is a substance that accelerates the diffusion rate of a substance that rate-determines the oxidation reaction of the healing agent (see Claim 1). Further, Patent Document 1 discloses that it is preferable to select a healing activator so that a self-healing function effective in the range of about 1050°C to 600°C is exhibited (for example, Paragraph

[0029] ).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present inventors have come to think that a highly useful sintered ceramic body could be provided if a self-healing function could be exhibited at a lower temperature.

[0006] The present invention has been made in view of the above-described problems, and an object thereof is to provide a ceramic powder capable of obtaining a sintered ceramic body in which a self-healing function is exhibited at a lower temperature. Another object is to provide a sintered ceramic body in which a self-healing function is exhibited at a lower temperature. Still another object is to provide a method for healing a sintered ceramic body using the sintered ceramic body.

Means for Solving the Problems

[0007] The present inventors have earnestly studied the above problems. As a result, surprisingly, they have found that the above problems can be solved by adopting the following configuration, and have completed the present invention.

[0008] The present invention provides the following. [1] A ceramic powder comprising zirconium carbide and partially stabilized zirconia, wherein the average particle diameter of the zirconium carbide is 1 μm or less, the average particle diameter of the partially stabilized zirconia is 1 μm or less, the content of the zirconium carbide is 15% by volume or more and 40% by volume or less, and the content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less.

[0009] The present inventors have found that when a sintered ceramic body using zirconium carbide as a healing agent is heated in a steam atmosphere, a self-healing function is exhibited at a lower temperature (for example, 550°C or lower, 500°C or lower, 450°C or lower, etc.) than in the past. Although the mechanism thereof is not clear, the present inventors have speculated as follows. First, when damage such as cracks occurs in a ceramic sintered body containing zirconium carbide as a healing agent, zirconium carbide (ZrC) is exposed at the crack portion. In this state, when heated at 350°C to 550°C for 1 hour or more in a steam atmosphere, hydroxides are formed on the surface of zirconium carbide (ZrC). Then, further, nuclei of ZrO 2 are generated, and crystals (nuclei) grow from the surface of the healing agent. Then, the reaction further proceeds, and when the dehydration of the hydroxide is completed, the healing is completed and the strength and the like are restored. According to the above configuration, since zirconium carbide is included, the ceramic sintered body obtained by sintering the ceramic powder exhibits a self-healing function when heated at 350°C to 550°C for 1 hour or more in a steam atmosphere.

[0010] Also, according to the above configuration, partially stabilized zirconia is included as a base material. Since partially stabilized zirconia is used as the base material, the self-healing function is exhibited at a low temperature in a steam atmosphere. Although the details of the reason are unknown, it is presumed that the same Zr-based material as the healing agent is used as the base material.

[0011] Also, according to the above configuration, since the average particle diameter of the zirconium carbide is 1 μm or less, it is preferably dispersed in the partially stabilized zirconia, and the initial strength of the obtained sintered body can be increased.

[0012] Also, according to the above configuration, since the average particle diameter of the partially stabilized zirconia is 1 μm or less, the zirconium carbide is preferably dispersed, and the initial strength of the obtained sintered body can be increased.

[0013] Also, according to the above configuration, since the content of the zirconium carbide is 15% by volume or more, a volume sufficient to fill the cracks can be ensured when it becomes ZrO 2 by steam heating. Also, according to the above configuration, since the content of the zirconium carbide is 40% by volume or less, it is preferably dispersed in the partially stabilized zirconia, and the initial strength of the obtained sintered body can be increased.

[0014] Also, according to the above configuration, since the content of the partially stabilized zirconia is 60% by volume or more, the content of the zirconium carbide can be 40% by volume or less. Further, since the content of the partially stabilized zirconia is 60% by volume or more, the initial strength of the obtained sintered body can be increased. Also, according to the above configuration, since the content of the partially stabilized zirconia is 85% by volume or less, the content of the zirconium carbide can be 15% by volume or more.

[0015] From the above, according to the above configuration, it is possible to provide a ceramic powder capable of obtaining a ceramic sintered body in which the self-healing function is exhibited at a lower temperature.

[0016] Furthermore, the present invention provides the following. [2] The average particle size of the partially stabilized zirconia is 0.7 μm or less, the content of the zirconium carbide is 15% by volume or more and 35% by volume or less, The ceramic powder according to [1] above, wherein the content of the partially stabilized zirconia is 65% by volume or more and 85% by volume or less.

[0017] When the average particle size of the partially stabilized zirconia is 0.7 μm or less, the zirconium carbide is more preferably dispersed, and the initial strength of the obtained sintered body can be increased.

[0018] Also, when the content of the zirconium carbide is 35% by volume or less, it is more preferably dispersed by the partially stabilized zirconia, and the initial strength of the obtained sintered body can be increased.

[0019] Also, when the content of the partially stabilized zirconia is 65% by volume or more, the content of the zirconium carbide can be 35% by volume or less. Further, when the content of the partially stabilized zirconia is 65% by volume or more, the initial strength of the obtained sintered body can be further increased.

[0020] Furthermore, the present invention provides the following. [3] The partially stabilized zirconia contains a stabilizer, The ceramic powder according to the above [1] or [2], wherein the stabilizer is one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc.

[0021] When the stabilizer is one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc, the strength of the sintered body can be further improved.

[0022] Furthermore, the present invention provides the following. [4] The ceramic powder according to the above [3], wherein the stabilizer is an oxide of Y.

[0023] When the stabilizer is an oxide of Y, the strength of the sintered body can be further improved.

[0024] Furthermore, the present invention provides the following. [5] Containing zirconium carbide and partially stabilized zirconia, The average particle size of the zirconium carbide is 1 μm or less, The average particle size of the partially stabilized zirconia is 1 μm or less, The content of the zirconium carbide is 15% by volume or more and 40% by volume or less, The content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less, A ceramic sintered body characterized in that the three-point bending strength of a test piece damaged under the following <damage-imparting conditions> and then healed under the following <healing conditions> is 70% or more compared to before damage. <Damage-imparting conditions> A Vickers indenter is pressed into a test piece of 3 mm × 4 mm × 44 mm with a force of 2 kgf to cause damage. <Healing conditions> Heat treatment is performed at 400 °C for 1 hour in a steam atmosphere.

[0025] According to the above structure, since it contains zirconium carbide, when heated at 350°C to 550°C for 1 hour or more in a steam atmosphere, the self-healing function is manifested.

[0026] Moreover, according to the above structure, it contains partially stabilized zirconia as the base material. Since partially stabilized zirconia is used as the base material, the self-healing function is manifested at a low temperature in a steam atmosphere. Although the reason for this is not clear in detail, it is presumed that this is because the same Zr-based material as the healing agent is used as the base material.

[0027] Furthermore, according to the above structure, since the average particle size of the zirconium carbide is 1 μm or less, it can be preferably dispersed in the partially stabilized zirconia, and the initial strength can be increased.

[0028] Also, according to the above structure, since the average particle size of the partially stabilized zirconia is 1 μm or less, the zirconium carbide can be preferably dispersed, and the initial strength can be increased.

[0029] Moreover, according to the above structure, since the content of the zirconium carbide is 15% by volume or more, it is possible to secure a volume sufficient to fill the cracks when it is heated with steam to become ZrO 2 when it becomes. In addition, according to the above structure, since the content of the zirconium carbide is 40% by volume or less, it can be preferably dispersed in the partially stabilized zirconia, and the initial strength can be increased.

[0030] Also, according to the above structure, since the content of the partially stabilized zirconia is 60% by volume or more, the content of the zirconium carbide can be made 40% by volume or less. Also, since the content of the partially stabilized zirconia is 60% by volume or more, the initial strength can be increased. Moreover, according to the above structure, since the content of the partially stabilized zirconia is 85% by volume or less, the content of the zirconium carbide can be made 15% by volume or more.

[0031] Moreover, according to the above configuration, after applying damage under the <damage application condition> and then healing under the <healing condition>, the three-point bending strength of the test piece is 70% or more compared to before applying the damage. Therefore, it can be said that the self-healing function is exhibited at a lower temperature.

[0032] As described above, according to the above configuration, it is possible to provide a ceramic sintered body in which the self-healing function is exhibited at a lower temperature.

[0033] Furthermore, the present invention provides the following. [6] A method for healing a ceramic sintered body, comprising a step of heat-treating the ceramic sintered body according to [5] in a steam atmosphere at 350°C or higher and 550°C or lower for 1 hour or more.

[0034] According to the above configuration, since the ceramic sintered body according to [5] is used, the ceramic sintered body can be healed even by heating at a low temperature of 350°C or higher and 550°C or lower.

[0035] It should be noted that the present invention is different from the conventional self-healing in the air. That is, in the present invention, even if the ceramic sintered body according to [5] is heated in the air instead of in a steam atmosphere, self-healing is not exhibited. When the ceramic sintered body according to [5] is heated to 400°C or higher in the air, cracks occur from the inside, oxidation is promoted by the cracks, and finally decomposition (powdering) occurs. Although the mechanism is not clear, the present inventors speculate as follows. First, when damage such as cracks occurs in a ceramic sintered body containing zirconium carbide, zirconium carbide (ZrC) is exposed at the crack portion. In this state, when heated in an air atmosphere, first, solid solution of O (oxygen) occurs, and an oxycarbide is generated. Then, nucleation proceeds from the inside of the oxycarbide, and cracks occur from the inside. And oxidation is promoted by the cracks, and finally decomposition (powdering) occurs. Thus, since the ceramic sintered body described in [5] can be decomposed (pulverized) when heated to 500°C or higher in the atmosphere, it can be recycled at the raw material level. That is, it is superior in usefulness compared to ordinary recycling that returns to the elemental level and recovers.

Advantages of the Invention

[0036] According to the present invention, it is possible to provide a ceramic powder capable of obtaining a ceramic sintered body in which a self-healing function is exhibited at a lower temperature. In addition, it is possible to provide a ceramic sintered body in which a self-healing function is exhibited at a lower temperature. Further, it is possible to provide a method for healing a ceramic sintered body using the ceramic sintered body.

Embodiments for Carrying Out the Invention

[0037] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited only to these embodiments. In this specification, zirconia is a general one and contains an impurity metal compound of 10% by mass or less including hafnia. Further, in this specification, the expressions "containing" and "including" include the concepts of "containing", "including", "substantially consisting of", and "consisting only of".

[0038] The maximum and minimum values of the content of each component shown below are the preferable minimum and maximum values of the present invention independently of the content of other components. Also, the maximum and minimum values of various parameters (measurement values, etc.) shown below are the preferable minimum and maximum values of the present invention independently of the content (composition) of each component.

[0039] [Ceramic Powder] The ceramic powder according to this embodiment is composed of zirconium carbide and partially stabilized zirconia, the average particle size of the zirconium carbide is 1 μm or less, The average particle diameter of the partially stabilized zirconia is 1 μm or less, the content of the zirconium carbide is 15% by volume or more and 40% by volume or less, the content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less.

[0040] As described above, the ceramic powder according to the present embodiment contains partially stabilized zirconia. Since partially stabilized zirconia is used as the base material, a self-healing function is exhibited at a low temperature in a steam atmosphere. Although the reason for this is not clear in detail, it is presumed that the same Zr-based material as the healing agent (zirconium carbide) is used as the base material.

[0041] When the total volume of the ceramic powder is 100% by volume, the content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less. Since the content of the partially stabilized zirconia is 60% by volume or more, the content of the zirconium carbide can be 40% by volume or less. Further, since the content of the partially stabilized zirconia is 60% by volume or more, the initial strength of the obtained sintered body can be increased. In addition, since the content of the partially stabilized zirconia is 85% by volume or less, the content of the zirconium carbide can be 15% by volume or more.

[0042] When the total volume of the ceramic powder is 100% by volume, the content of the partially stabilized zirconia is preferably 65% by volume or more, more preferably 68% by volume or more, and still more preferably 70% by volume or more. When the total volume of the ceramic powder is 100% by volume, the content of the partially stabilized zirconia is preferably 80% by volume or less, more preferably 75% by volume or less, and still more preferably 72% by volume or less. When the total volume of the ceramic powder is 100% by volume, the content of the partially stabilized zirconia is preferably 65% by volume or more and 80% by volume or less, more preferably 68% by volume or more and 75% by volume or less, and still more preferably 68% by volume or more and 72% by volume.

[0043] The average particle size of the partially stabilized zirconia is 1 μm or less. Since the average particle size of the partially stabilized zirconia is 1 μm or less, zirconium carbide can be preferably dispersed, and the initial strength of the obtained sintered body can be increased.

[0044] The average particle size of the partially stabilized zirconia is preferably 0.7 μm or less, more preferably 0.5 μm or less. The average particle size of the partially stabilized zirconium is preferably small, for example, 0.1 μm or more, more preferably 0.3 μm or more. The average particle size of the partially stabilized zirconium is preferably 0.1 μm or more and 1 μm or less, more preferably 0.3 μm or more and 0.8 μm or less, still more preferably 0.3 μm or more and 0.6 μm or less.

[0045] The partially stabilized zirconia contains zirconia and a stabilizer.

[0046] When the total content of zirconia and the stabilizer in the partially stabilized zirconia is 100% by mass of the entire partially stabilized zirconia, it is preferably 70% by mass or more, more preferably 80% by mass or more. The total content of zirconia and the stabilizer can be 99% by mass or less, 95% by mass or less, etc. when the entire partially stabilized zirconia is 100% by mass. When the total content of zirconia and the stabilizer in the partially stabilized zirconia is 100% by mass of the entire partially stabilized zirconia, it is preferably 70% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 95% by mass or less. Also, the partially stabilized zirconia may be composed of only zirconia and a stabilizer.

[0047] The stabilizer is not particularly limited, but is preferably one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc. When the stabilizer is one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc, the strength of the sintered body can be further improved.

[0048] Among them, the stabilizer is more preferably an oxide of Y. When the stabilizer is an oxide of Y, the strength of the sintered body can be further improved.

[0049] The total amount of the stabilizer in the partially stabilized zirconia is preferably 2.0 mol% or more and 14 mol% or less in terms of oxide. When the total amount of the stabilizer is 2.0 mol% or more in terms of oxide, the strength of the sintered body obtained by sintering the ceramic powder can be further improved. Also, when the total amount of the stabilizer is 14 mol% or less in terms of oxide, partially stabilized zirconia is formed and the desired strength can be obtained.

[0050] The total amount of the stabilizer is more preferably 2.2 mol% or more, even more preferably 2.5 mol% or more, particularly preferably 3 mol% or more, and especially preferably 4 mol% or more in terms of oxide. The total amount of the stabilizer is more preferably 9 mol% or less, even more preferably 8 mol% or less, particularly preferably 7 mol% or less, and especially preferably 6 mol% or less in terms of oxide. The total amount of the stabilizer is more preferably 2.2 mol% or more and 9 mol% or less, even more preferably 2.5 mol% or more and 8 mol% or less, particularly preferably 3 mol% or more and 7 mol% or less, and especially preferably 4 mol% or more and 6 mol% or less in terms of oxide.

[0051] When the stabilizer is only Y 2 O 3 , with respect to the entire ceramic powder, the Y 2 O 3The content is preferably 2 mol% or more, more preferably 2.2 mol% or more, still more preferably 2.5 mol% or more, particularly preferably 2.7 mol% or more, and especially preferably 2.9 mol% or more. When the stabilizer is only Y 2 O 3 only, the content of the Y 2 O 3 in the whole ceramic powder is preferably 8 mol% or less, more preferably 7 mol% or less, still more preferably 6 mol% or less, particularly preferably 5 mol% or less, and especially preferably 4 mol% or less. When the stabilizer is only Y 2 O 3 only, the content of the Y 2 O 3 in the whole ceramic powder is preferably 2 mol% or more and 8 mol% or less, more preferably 2.2 mol% or more and 7 mol% or less, still more preferably 2.5 mol% or more and 6 mol% or less, particularly preferably 2.7 mol% or more and 5 mol% or less, and especially preferably 2.9 mol% or more and 4 mol% or less.

[0052] When the stabilizer is only CaO, the content of the CaO in the whole ceramic powder is preferably 4 mol% or more, more preferably 5 mol% or more. When the stabilizer is only CaO, the content of the CaO in the whole ceramic powder is preferably 8 mol% or less, more preferably 7 mol% or less. When the stabilizer is only CaO, the content of the CaO in the whole ceramic powder is preferably 4 mol% or more and 8 mol% or less, more preferably 5 mol% or more and 7 mol% or less.

[0053] When the stabilizer is only MgO, the content of the MgO in the whole ceramic powder is preferably 8 mol% or more, more preferably 9 mol% or more. When the stabilizer is only MgO, the content of MgO in the whole ceramic powder is preferably 12 mol% or less, more preferably 11 mol% or less. When the stabilizer is only MgO, the content of MgO in the whole ceramic powder is preferably 8 mol% or more and 10 mol% or less, more preferably 9 mol% or more and 11 mol% or less.

[0054] When the stabilizer is only CeO 2 the content of CeO 2 in the whole ceramic powder is preferably 10 mol% or more, more preferably 11 mol% or more. When the stabilizer is only CeO 2 the content of CeO 2 in the whole ceramic powder is preferably 13 mol% or less, more preferably 12 mol% or less. When the stabilizer is only CeO 2 the content of CeO 2 in the whole ceramic powder is preferably 10 mol% or more and 14 mol% or less, more preferably 11 mol% or more and 13 mol% or less.

[0055] When the stabilizer is only Yb 2 O 3 the content of Yb 2 O 3 in the whole ceramic powder is preferably 2 mol% or more, more preferably 2.2 mol% or more, still more preferably 2.5 mol% or more, particularly preferably 2.7 mol% or more, and especially preferably 2.9 mol% or more. When the stabilizer is only Yb 2 O 3 the content of Yb 2 O 3 in the whole ceramic powder is preferably 8 mol% or less, more preferably 7 mol% or less, still more preferably 6 mol% or less, particularly preferably 5 mol% or less, and especially preferably 4 mol% or less. When the stabilizer is only Yb2 O 3 only, the content of said Yb 2 O 3 in the whole ceramic powder is preferably 2 mol% or more and 8 mol% or less, more preferably 2.2 mol% or more and 7 mol% or less, still more preferably 2.5 mol% or more and 6 mol% or less, particularly preferably 2.7 mol% or more and 5 mol% or less, and especially preferably 2.9 mol% or more and 4 mol% or less.

[0056] When the stabilizer is Er 2 O 3 only, the content of said Er 2 O 3 in the whole ceramic powder is preferably 2 mol% or more, more preferably 2.2 mol% or more, still more preferably 2.5 mol% or more, particularly preferably 2.7 mol% or more, and especially preferably 2.9 mol% or more. When the stabilizer is Er 2 O 3 only, the content of said Er 2 O 3 in the whole ceramic powder is preferably 8 mol% or less, more preferably 7 mol% or less, still more preferably 6 mol% or less, particularly preferably 5 mol% or less, and especially preferably 4 mol% or less. When the stabilizer is Er 2 O 3 only, the content of said Er 2 O 3 in the whole ceramic powder is preferably 2 mol% or more and 8 mol% or less, more preferably 2.2 mol% or more and 7 mol% or less, still more preferably 2.5 mol% or more and 6 mol% or less, particularly preferably 2.7 mol% or more and 5 mol% or less, and especially preferably 2.9 mol% or more and 4 mol% or less.

[0057] When the stabilizer is Sc 2 O 3 only, the content of said Sc 2 O 3The content of [substance] is preferably 2 mol% or more, more preferably 4 mol% or more. When the stabilizer is Sc 2 O 3 only, the content of the above-mentioned Sc 2 O 3 in the entire ceramic powder is preferably 12 mol% or less, more preferably 10 mol% or less. When the stabilizer is Sc 2 O 3 only, the content of the above-mentioned Sc 2 O 3 in the entire ceramic powder is preferably 2 mol% or more and 14 mol% or less, more preferably 4 mol% or more and 10 mol% or less.

[0058] The content of zirconia in the partially stabilized zirconia is preferably 80% by mass or more and 99% by mass or less. The content of zirconia in the partially stabilized zirconia is more preferably 85% by mass or more, and even more preferably 90% by mass or more. The content of zirconia in the partially stabilized zirconia is more preferably 98% by mass or less, and even more preferably 97% by mass or less. The content of zirconia in the partially stabilized zirconia is more preferably 85% by mass or more and 98% by mass or less, and even more preferably 90% by mass or more and 97% by mass or less.

[0059] The partially stabilized zirconia can be produced by a conventionally known method. The partially stabilized zirconia can be produced, for example, by the method disclosed in Japanese Patent No. 7195482.

[0060] The ceramic powder contains zirconium carbide (ZrC). Because it contains zirconium carbide, when the ceramic sintered body obtained by sintering the ceramic powder is heated at 350°C to 550°C for 1 hour or more in a steam atmosphere, a self-healing function is exhibited.

[0061] When the content of the zirconium carbide is based on 100% by volume of the entire ceramic powder, it is 15% by volume or more and 40% by volume or less. Since the content of the zirconium carbide is 15% by volume or more, when it is heated with steam to become ZrO 2 it is possible to secure a volume sufficient to fill the cracks. Also, since the content of the zirconium carbide is 40% by volume or less, it can be preferably dispersed in the partially stabilized zirconia, and the initial strength of the obtained sintered body can be increased.

[0062] When the content of the zirconium carbide is based on 100% by volume of the entire ceramic powder, it is preferably 15% by volume or more, more preferably 20% by volume or more, and still more preferably 25% by volume. When the content of the zirconium carbide is based on 100% by volume of the entire ceramic powder, it is preferably 35% by volume or less, more preferably 32% by volume or less, and still more preferably 30% by volume or less. When the content of the zirconium carbide is based on 100% by volume of the entire ceramic powder, it is preferably 15% by volume or more and 35% by volume or less, more preferably 20% by volume or more and 32% by volume or less, and still more preferably 25% by volume or more and 30% by volume or less.

[0063] The average particle diameter of the zirconium carbide is 1 μm or less. Since the average particle diameter of the zirconium carbide is 1 μm or less, it can be preferably dispersed in the partially stabilized zirconia, and the initial strength of the obtained sintered body can be increased.

[0064] The average particle diameter of the zirconium carbide is preferably 0.9 μm or less, and more preferably 0.84 μm or less. The smaller the average particle diameter of the zirconium carbide, the better. For example, 0.3 μm or more, 0.5 μm or more, 0.56 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more can be mentioned.

[0065] The zirconium carbide can be produced by a conventionally known method. Also, a commercially available product of zirconium carbide can be used. When using a commercially available product, it may be used after adjusting the average particle diameter to a desired range using known pulverization means (for example, a planetary mill, etc.).

[0066] The ceramic powder may contain Al 2 O 3 (alumina) within a range of 0.005 mass% or more and 2 mass% or less. When the ceramic powder contains Al 2 O 3 , it functions as a sintering aid, so it has excellent low-temperature sinterability.

[0067] When the ceramic powder contains Al 2 O 3 , the content of the Al 2 O 3 is more preferably 0.01 mass% or more, still more preferably 0.03 mass% or more, particularly preferably 0.05 mass% or more, especially preferably 0.1 mass% or more, and particularly preferably 0.2 mass% or more. When the ceramic powder contains Al 2 O 3 , the content of the Al 2 O 3 is more preferably 1 mass% or less, still more preferably 0.5 mass% or less, particularly preferably 0.3 mass% or less, especially preferably 0.25 mass% or less. When the ceramic powder contains Al 2 O 3 , the content of the Al 2 O 3 is more preferably 0.05 mass% or more and 0.5 mass% or less, still more preferably 0.1 mass% or more and 0.25 mass% or less.

[0068] In addition to alumina, the ceramic powder may contain sinterable ceramics, thermosetting resins, etc. for the purpose of improving characteristics such as strength.

[0069] <Specific surface area> The specific surface area of the ceramic powder is preferably 15 m 2 / g or more and 60 m 2 / g or less. The specific surface area is preferably 20 m 2 / g or more, more preferably 22 m 2 / g or more. The specific surface area is preferably 50 m 2 / g or less, more preferably 40 m 2 / g or less, still more preferably 30 m 2 / g or less, particularly preferably 28 m 2 / g or less. The specific surface area is preferably 20 m 2 / g or more and 50 m 2 / g or less, more preferably 22 m 2 / g or more and 40 m 2 / g or less, still more preferably 22 m 2 / g or more and 30 m 2 / g or less, particularly preferably 22 m 2 / g or more and 28 m 2 / g or less.

[0070] The ceramic powder can be obtained by mixing the partially stabilized zirconia and the zirconium carbide. As a more detailed method of mixing, it is preferable to disperse in ethanol, pure water, etc. to form a slurry and perform wet mixing. After wet mixing, it is preferable to dry and size the particles through a sieve or the like. The mixing is preferably carried out in a manner such that the partially stabilized zirconia particles and the zirconium carbide are not pulverized. However, the manufacturing method of the ceramic powder is not limited to the above.

[0071] The ceramic powder according to the present embodiment has been described above.

[0072] [Ceramic Sintered Body] The sintered body according to the present embodiment contains zirconium carbide and partially stabilized zirconia, the average particle diameter of the zirconium carbide is 1 μm or less, The average particle size of the partially stabilized zirconia is 1 μm or less, the content of the zirconium carbide is 15% by volume or more and 40% by volume or less, the content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less, After applying damage under the following <Damage Imposing Conditions>, the three-point bending strength of the test piece cured under the following <Healing Conditions> is 70% or more compared to before applying damage. <Damage Imposing Conditions> A Vickers indenter is pressed into a 3 mm × 4 mm × 44 mm test piece with a force of 2 kgf to introduce damage. <Healing Conditions> Heat treatment is performed at 400 °C for 1 hour in a steam atmosphere.

[0073] As described above, the ceramic sintered body according to the present embodiment contains partially stabilized zirconia. Since partially stabilized zirconia is used as the base material, a self-healing function is exhibited at a low temperature in a steam atmosphere. Although the reason for this is not clear in detail, it is presumed that the same Zr-based material as the healing agent (zirconium carbide) is used as the base material.

[0074] The content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less when the entire ceramic sintered body is 100% by volume. Since the content of the partially stabilized zirconia is 60% by volume or more, the content of the zirconium carbide can be 40% by volume or less. Further, since the content of the partially stabilized zirconia is 60% by volume or more, the initial strength of the sintered body can be increased. Also, since the content of the partially stabilized zirconia is 85% by volume or less, the content of the zirconium carbide can be 15% by volume or more.

[0075] The content of the partially stabilized zirconia is preferably 65% by volume or more, more preferably 68% by volume or more, and still more preferably 70% by volume or more when the entire ceramic powder is 100% by volume. When the total amount of the ceramic powder is 100% by volume, the content of the partially stabilized zirconia is preferably 80% by volume or less, more preferably 75% by volume or less, and still more preferably 72% by volume or less. When the total amount of the ceramic powder is 100% by volume, the content of the partially stabilized zirconia is preferably 65% to 80% by volume, more preferably 68% to 75% by volume, and still more preferably 68% to 72% by volume.

[0076] The average particle size of the partially stabilized zirconia is 1 μm or less. Since the average particle size of the partially stabilized zirconia is 1 μm or less, zirconium carbide can be preferably dispersed, and the initial strength of the sintered body can be increased.

[0077] The average particle size of the zirconium carbide is preferably 0.9 μm or less, more preferably 0.84 μm or less. Although it is preferable that the average particle size of the zirconium carbide is small, for example, 0.3 μm or more, 0.5 μm or more, 0.56 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more can be mentioned.

[0078] The partially stabilized zirconia contains zirconia and a stabilizer.

[0079] When the total amount of the partially stabilized zirconia is 100% by mass, the total content of zirconia and the stabilizer in the partially stabilized zirconia is preferably 70% by mass or more, and more preferably 80% by mass or more. When the total amount of the partially stabilized zirconia is 100% by mass, the total content of zirconia and the stabilizer can be 99% by mass or less, 95% by mass or less, etc. When the total amount of the partially stabilized zirconia is 100% by mass, the total content of zirconia and the stabilizer in the partially stabilized zirconia is preferably 70% to 99% by mass, and more preferably 80% to 95% by mass. Also, the partially stabilized zirconia may be composed of only zirconia and a stabilizer.

[0080] The stabilizer is not particularly limited, but is preferably one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc. When the stabilizer is one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc, the strength of the sintered body can be further improved.

[0081] Among them, the stabilizer is more preferably an oxide of Y. When the stabilizer is an oxide of Y, the strength of the sintered body can be further improved.

[0082] The total amount of the stabilizer in the partially stabilized zirconia is preferably 2.0 mol% or more and 14 mol% or less in terms of oxide. When the total amount of the stabilizer is 2.0 mol% or more in terms of oxide, the strength of the sintered body obtained by sintering the ceramic powder can be further improved. Also, when the total amount of the stabilizer is 14 mol% or less in terms of oxide, partially stabilized zirconia is formed and the desired strength can be obtained.

[0083] The total amount of the stabilizer is more preferably 2.2 mol% or more, further preferably 2.5 mol% or more, particularly preferably 3 mol% or more, and especially preferably 4 mol% or more in terms of oxide. The total amount of the stabilizer is more preferably 9 mol% or less, further preferably 8 mol% or less, particularly preferably 7 mol% or less, and especially preferably 6 mol% or less in terms of oxide. The total amount of the stabilizer is more preferably 2.2 mol% or more and 9 mol% or less, further preferably 2.5 mol% or more and 8 mol% or less, particularly preferably 3 mol% or more and 7 mol% or less, and especially preferably 4 mol% or more and 6 mol% or less in terms of oxide.

[0084] When the stabilizer is only Y 2 O 3 , with respect to the entire ceramic sintered body, the Y 2 O 3The content is preferably 2 mol% or more, more preferably 2.2 mol% or more, still more preferably 2.5 mol% or more, particularly preferably 2.7 mol% or more, and especially preferably 2.9 mol% or more. When the stabilizer is only Y 2 O 3 only, the content of the Y 2 O 3 in the entire ceramic sintered body is preferably 8 mol% or less, more preferably 7 mol% or less, still more preferably 6 mol% or less, particularly preferably 5 mol% or less, and especially preferably 4 mol% or less. When the stabilizer is only Y 2 O 3 only, the content of the Y 2 O 3 in the entire ceramic sintered body is preferably 2 mol% or more and 8 mol% or less, more preferably 2.2 mol% or more and 7 mol% or less, still more preferably 2.5 mol% or more and 6 mol% or less, particularly preferably 2.7 mol% or more and 5 mol% or less, and especially preferably 2.9 mol% or more and 4 mol% or less.

[0085] When the stabilizer is only CaO, the content of the CaO in the entire ceramic sintered body is preferably 4 mol% or more, more preferably 5 mol% or more. When the stabilizer is only CaO, the content of the CaO in the entire ceramic sintered body is preferably 8 mol% or less, more preferably 7 mol% or less. When the stabilizer is only CaO, the content of the CaO in the entire ceramic sintered body is preferably 4 mol% or more and 8 mol% or less, more preferably 5 mol% or more and 7 mol% or less.

[0086] When the stabilizer is only MgO, the content of the MgO in the entire ceramic sintered body is preferably 8 mol% or more, more preferably 9 mol% or more. When the stabilizer is only MgO, the content of MgO in the entire ceramic sintered body is preferably 12 mol% or less, more preferably 11 mol% or less. When the stabilizer is only MgO, the content of MgO in the entire ceramic sintered body is preferably 8 mol% or more and 10 mol% or less, more preferably 9 mol% or more and 11 mol% or less.

[0087] When the stabilizer is only CeO 2 the content of CeO 2 in the entire ceramic sintered body is preferably 10 mol% or more, more preferably 11 mol% or more. When the stabilizer is only CeO 2 the content of CeO 2 in the entire ceramic sintered body is preferably 13 mol% or less, more preferably 12 mol% or less. When the stabilizer is only CeO 2 the content of CeO 2 in the entire ceramic sintered body is preferably 10 mol% or more and 14 mol% or less, more preferably 11 mol% or more and 13 mol% or less.

[0088] When the stabilizer is only Yb 2 O 3 the content of Yb 2 O 3 in the entire ceramic sintered body is preferably 2 mol% or more, more preferably 2.2 mol% or more, still more preferably 2.5 mol% or more, particularly preferably 2.7 mol% or more, and especially preferably 2.9 mol% or more. When the stabilizer is only Yb 2 O 3 the content of Yb 2 O 3 in the entire ceramic sintered body is preferably 8 mol% or less, more preferably 7 mol% or less, still more preferably 6 mol% or less, particularly preferably 5 mol% or less, and especially preferably 4 mol% or less. When the stabilizer is only Yb2 O 3 only, the content of Yb in the whole ceramic sintered body 2 O 3 is preferably 2 mol% or more and 8 mol% or less, more preferably 2.2 mol% or more and 7 mol% or less, still more preferably 2.5 mol% or more and 6 mol% or less, particularly preferably 2.7 mol% or more and 5 mol% or less, and especially preferably 2.9 mol% or more and 4 mol% or less.

[0089] When the stabilizer is Er 2 O 3 only, the content of Er in the whole ceramic sintered body 2 O 3 is preferably 2 mol% or more, more preferably 2.2 mol% or more, still more preferably 2.5 mol% or more, particularly preferably 2.7 mol% or more, and especially preferably 2.9 mol% or more. When the stabilizer is Er 2 O 3 only, the content of Er in the whole ceramic sintered body 2 O 3 is preferably 8 mol% or less, more preferably 7 mol% or less, still more preferably 6 mol% or less, particularly preferably 5 mol% or less, and especially preferably 4 mol% or less. When the stabilizer is Er 2 O 3 only, the content of Er in the whole ceramic sintered body 2 O 3 is preferably 2 mol% or more and 8 mol% or less, more preferably 2.2 mol% or more and 7 mol% or less, still more preferably 2.5 mol% or more and 6 mol% or less, particularly preferably 2.7 mol% or more and 5 mol% or less, and especially preferably 2.9 mol% or more and 4 mol% or less.

[0090] When the stabilizer is Sc 2 O 3 only, the content of Sc in the whole ceramic sintered body 2 O 3The content of [substance] is preferably 2 mol% or more, more preferably 4 mol% or more. When the stabilizer is Sc 2 O 3 only, the content of the Sc 2 O 3 in the entire ceramic sintered body is preferably 12 mol% or less, more preferably 10 mol% or less. When the stabilizer is Sc 2 O 3 only, the content of the Sc 2 O 3 in the entire ceramic sintered body is preferably 2 mol% or more and 14 mol% or less, more preferably 4 mol% or more and 10 mol% or less.

[0091] The content of zirconia in the partially stabilized zirconia is preferably 80% by mass or more and 99% by mass or less. The content of zirconia in the partially stabilized zirconia is more preferably 85% by mass or more, and even more preferably 90% by mass or more. The content of zirconia in the partially stabilized zirconia is more preferably 98% by mass or less, and even more preferably 97% by mass or less. The content of zirconia in the partially stabilized zirconia is more preferably 85% by mass or more and 98% by mass or less, and even more preferably 90% by mass or more and 97% by mass or less.

[0092] The ceramic sintered body contains zirconium carbide (ZrC). Because it contains zirconium carbide, when heated at 350 °C to 550 °C for 1 hour or more in a steam atmosphere, a self-healing function is exhibited.

[0093] The content of the zirconium carbide is 15% by volume or more and 40% by volume or less when the entire ceramic sintered body is 100% by volume. Because the content of the zirconium carbide is 15% by volume or more, when heated with steam to ZrO 2When it becomes like this, it is possible to secure a volume sufficient to fill the cracks. Further, since the content of the zirconium carbide is 40% by volume or less, it is suitably dispersed in the partially stabilized zirconia, and the initial strength of the sintered body can be increased.

[0094] When the total volume of the ceramic powder is 100% by volume, the content of the zirconium carbide is preferably 15% by volume or more, more preferably 20% by volume or more, and still more preferably 25% by volume. When the total volume of the ceramic powder is 100% by volume, the content of the zirconium carbide is preferably 35% by volume or less, more preferably 32% by volume or less, and still more preferably 30% by volume or less. When the total volume of the ceramic powder is 100% by volume, the content of the zirconium carbide is preferably 15% by volume or more and 35% by volume or less, more preferably 20% by volume or more and 32% by volume or less, and still more preferably 25% by volume or more and 30% by volume or less.

[0095] The average particle diameter of the zirconium carbide is 1 μm or less. Since the average particle diameter of the zirconium carbide is 1 μm or less, it is suitably dispersed in the partially stabilized zirconia, and the initial strength of the sintered body can be increased.

[0096] The average particle diameter of the zirconium carbide is preferably 0.9 μm or less, more preferably 0.84 μm or less. Although it is preferable that the average particle diameter of the zirconium carbide is small, for example, 0.3 μm or more, 0.5 μm or more, 0.56 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more can be mentioned.

[0097] The zirconium carbide can be produced by a conventionally known method. Further, a commercially available product can also be used as the zirconium carbide. When using a commercially available product, it may be used after adjusting the average particle diameter to a desired range using known pulverization means (for example, a planetary mill, etc.).

[0098] The ceramic sintered body is Al with respect to the entire zirconia sintered body 2 O3 It may contain (alumina) within the range of 0.005 mass% or more and 2 mass% or less. With respect to the entire ceramic sintered body, Al 2 O 3 is contained, it functions as a sintering aid, and thus has excellent low-temperature sinterability.

[0099] When the ceramic sintered body contains Al 2 O 3 the content of the above-mentioned Al 2 O 3 is more preferably 0.01 mass% or more, still more preferably 0.03 mass% or more, particularly preferably 0.05 mass% or more, especially preferably 0.1 mass% or more, and particularly preferably 0.2 mass% or more. When the ceramic sintered body contains Al 2 O 3 the content of the above-mentioned Al 2 O 3 is more preferably 1 mass% or less, still more preferably 0.5 mass% or less, particularly preferably 0.3 mass% or less, especially preferably 0.25 mass% or less. When the ceramic sintered body contains Al 2 O 3 the content of the above-mentioned Al 2 O 3 is more preferably 0.05 mass% or more and 0.5 mass% or less, still more preferably 0.1 mass% or more and 0.25 mass% or less.

[0100] In addition to alumina, the ceramic sintered body may contain sinterable ceramics, thermosetting resins, etc. for the purpose of improving properties such as strength.

[0101] (Relative sintered density) The relative sintered density of the ceramic sintered body is preferably 99.5% or more, more preferably 99.7% or more, still more preferably 99.8% or more, particularly preferably 99.82% or more, and especially preferably 99.85% or more. When the relative sintered density is 99.5% or more, the ceramic sintered body has higher strength.

[0102] (Flexural strength (before damage)) The flexural strength (before damage) of the ceramic sintered body is preferably 500 MPa or more, more preferably 800 MPa or more, and even more preferably 1000 MPa or more. The higher the flexural strength (before damage), the more preferable, but it is 1300 MPa or less, 1500 MPa or less, etc.

[0103] (Strength recovery rate) After the ceramic sintered body is damaged under the following <Damage-imparting conditions>, the flexural strength of the test piece cured under the following <Healing conditions> is 70% or more compared to before damage. Since the flexural strength of the test piece cured under the following <Healing conditions> after being damaged under the following <Damage-imparting conditions> is 70% or more compared to before damage, it can be said that the self-healing function is exhibited at a lower temperature. In the following, the flexural strength of the test piece cured under the following <Healing conditions> after being damaged under the following <Damage-imparting conditions>, compared to before damage, will also be referred to as the "strength recovery rate". <Damage-imparting conditions> A Vickers indenter is pressed into a 3 mm × 4 mm × 44 mm test piece with a force of 2 kgf to cause damage. <Healing conditions> Heat treatment is performed at 400 °C for 1 hour in a water vapor atmosphere.

[0104] The strength recovery rate is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, particularly preferably 95% or more, and especially preferably 99% or more. Note that when the flexural strength after healing after damage is higher than the flexural strength before damage, the strength recovery rate will exceed 100%. The higher the strength recovery rate, the more preferable, but for example, it is 160% or less, 200% or less, etc.

[0105] The flexural strength refers to the value obtained by the method described in the examples.

[0106] The above is the description of the ceramic sintered body according to this embodiment.

[0107] The zirconia sintered body according to this embodiment is not particularly limited. For example, it can be obtained by using the above ceramic powder and the manufacturing method of the zirconia sintered body described later.

[0108] The zirconia sintered body according to this embodiment can be used as a structural ceramic. More specifically, it can be used for gears, screws, kitchen knives, etc. In particular, conventionally, in order to exhibit the self-healing function, it is necessary to heat to a very high temperature (for example, 600°C to 1050°C). For this purpose, the parts made of the ceramic sintered body had to be disassembled and put into a furnace. On the other hand, when the zirconia sintered body according to this embodiment is heated at 350°C to 550°C for 1 hour or more in a steam atmosphere, the self-healing function is exhibited, so there is no need to put it into a furnace. Therefore, there is no need to disassemble the parts to exhibit the self-healing function. For example, if a device that generates steam at about 400°C is used, the steam can be directly applied to the relevant part to exhibit the self-healing function.

[0109] [Manufacturing method of ceramic sintered body] Hereinafter, an example of the manufacturing method of the ceramic sintered body will be described. However, the manufacturing method of the ceramic sintered body of the present invention is not limited to the following examples.

[0110] The manufacturing method of the ceramic sintered body according to this embodiment includes step A of preparing ceramic powder and step B of sintering the ceramic powder.

[0111] <Step A> In the manufacturing method of the ceramic sintered body according to this embodiment, first, ceramic powder is prepared (step A). As the ceramic powder, those described in the section of [Ceramic powder] can be used.

[0112] Next, if necessary, the ceramic powder is press-molded. The press molding is not particularly limited, but uniaxial pressing can be used. As the pressing pressure, for example, 50 to 500 MPa is preferable, and 80 to 200 MPa is more preferable.

[0113] <Process B> Next, the ceramic powder is sintered (Process B). Thereby, a ceramic sintered body is obtained. The heat treatment temperature, time, and pressing pressure during sintering are not particularly limited, but a heat treatment temperature of 1000°C to 1500°C, a time of 1 to 5 hours, and a pressing pressure of 10 to 50 MPa are preferable. The heat treatment atmosphere is preferably an air atmosphere or an oxidizing atmosphere.

[0114] The manufacturing method of the stabilized zirconia sintered body according to the present embodiment has been described above.

[0115] [Method for healing a ceramic sintered body] The method for healing a ceramic sintered body according to the present embodiment is characterized by having a step A of heat-treating the ceramic sintered body in a steam atmosphere at 350°C or higher and 550°C or lower for 1 hour or more.

[0116] The temperature in the step A is preferably 350°C or higher, more preferably 400°C or higher. Also, the temperature in the step A is preferably 530°C or lower, more preferably 500°C or lower, from the viewpoint that a furnace may not be used even if the temperature is higher. The temperature in the step A is preferably 400°C or higher and 550°C or lower, more preferably 400°C or higher and 530°C or lower, still more preferably 400°C or higher and 500°C or lower.

[0117] The time of the step A is preferably 0.8 hours or more, more preferably 1 hour or more. Since there is no need to heat further if the curing is completed, the time for the process A is preferably 2 hours or less, more preferably 1.3 hours or less, considering the time required for curing. The time for the process A is preferably 0.8 hours or more and 2 hours or less, more preferably 1 hour or more and 1.3 hours or less.

[0118] In the method for curing the ceramic sintered body, self-healing occurs even if the temperature in the process A exceeds 550°C. However, since it is not easy to create a water vapor atmosphere exceeding 550°C, it is preferably 550°C or less. In the method for curing the ceramic sintered body, self-healing occurs even if the temperature in the process A is less than 350°C (for example, about 200°C). However, since it takes time for self-healing to be completed when the temperature is low (for example, about 48 hours at 200°C), considering productivity, 350°C or more is preferable, and more preferably 400°C or more.

[0119] According to the method for curing the ceramic sintered body, since the ceramic sintered body is used, the ceramic sintered body can be cured (strength recovery) even by heating at a low temperature of 350°C or more and 550°C or less.

Examples

[0120] Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the ceramic powder and the ceramic sintered body in the examples and comparative examples, hafnium oxide is contained as an inevitable impurity in an amount of 1.3 to 2.5% by mass based on zirconium oxide (calculated by the following formula (X)). <Formula (X)> ([Mass of hafnium oxide] / ([Mass of zirconium oxide]+[Mass of hafnium oxide]))×100 (%)

[0121] [Production of ceramic powder] (Production Example 1) As the base material, yttria partially stabilized zirconia (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) containing 3 mol% of Y 2 O 3 was prepared. The particle size of the prepared yttria partially stabilized zirconia was adjusted to 0.49 μm using a planetary mill. The particle size was measured according to the following particle size measurement method. The results are shown in Table 1. Also, zirconium carbide (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) was prepared as a healing agent. The particle size of the prepared zirconium carbide was adjusted by a planetary mill to an average particle size of 1 μm. Specifically, zirconium carbide (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd., FSZ-003) as a healing agent was pulverized using a planetary mill under the following pulverization conditions. <Pulverization conditions> Planetary mill (model number: Pulverisette6, manufacturer: FRITSCH) Processing conditions (500 cc zirconia pot, 2 mm zirconia balls: 900 g, ethanol 150 g, sample: 100 g, rotation speed: 400 rpm, pulverization for 30 min) Next, zirconium carbide was weighed so that it was 30 vol% and yttria partially stabilized zirconia was 70 vol%. Next, the weighed zirconium carbide and yttria partially stabilized zirconia were placed in a glass bottle, nylon balls and ethanol were added, and ball milling (mixing) was performed for 24 hours. Then, the slurry was heated and dried at 60 to 80°C. Thus, the ceramic powder according to Production Example 1 was obtained. In Table 1, "3YSZ" means yttria partially stabilized zirconia containing 3 mol% of Y 2 O 3

[0122] (Production Example 2) A ceramic powder according to Production Example 2 was obtained in the same manner as in Production Example 1, except that the blending ratio of zirconium carbide and yttria partially stabilized zirconia was such that zirconium carbide was 15 vol% and yttria partially stabilized zirconia was 85 vol%.

[0123] (Production Example 3) ​A ceramic powder according to Production Example 3 was obtained in the same manner as in Production Example 1, except that the particle size of zirconium carbide was adjusted by a planetary mill to have an average particle size of 0.84 μm. Specifically, zirconium carbide (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) as a healing agent was pulverized using a planetary mill under the following pulverization conditions. <Pulverization conditions> Planetary mill (model number: Pulverisette6, manufacturer: FRITSCH) Processing conditions (500 cc zirconia pot, 2 mm zirconia balls: 900 g, ethanol 150 g, sample: 100 g, rotation speed: 400 rpm, pulverization for 45 minutes)

[0124] (Production Example 4) A ceramic powder according to Production Example 4 was obtained in the same manner as in Production Example 1, except that the particle size of zirconium carbide was adjusted by a planetary mill to have an average particle size of 1.5 μm. Specifically, zirconium carbide (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) as a healing agent was pulverized using a planetary mill under the following pulverization conditions. <Pulverization conditions> Planetary mill (model number: Pulverisette6, manufacturer: FRITSCH) Processing conditions (500 cc zirconia pot, 2 mm zirconia balls: 900 g, ethanol 150 g, sample: 100 g, rotation speed: 400 rpm, pulverization for 15 minutes)

[0125] (Production Example 5) A ceramic powder according to Production Example 5 was obtained in the same manner as in Production Example 1, except that the blending ratio of zirconium carbide and yttria partially stabilized zirconia was adjusted so that zirconium carbide was 10% by volume and yttria partially stabilized zirconia was 90% by volume.

[0126] (Production Example 6) A ceramic powder according to Production Example 6 was obtained in the same manner as in Production Example 1, except that the particle size of yttria partially stabilized zirconia was adjusted by a planetary mill to have an average particle size of 1.3 μm.

[0127] (Production Example 7) Mullite (type number: KCM101, manufacturer: KCM Corporation, particle size: 1.9 μm) was prepared as a healing agent. A ceramic powder according to Production Example 7 was obtained in the same manner as in Production Example 1, except that the mullite prepared in this Production Example 7 was used as the healing agent.

[0128] (Production Example 8) A ceramic powder according to Production Example 8 was obtained in the same manner as in Production Example 1, except that no healing agent was used.

[0129] [Measurement of Average Particle Size of Partially Stabilized Zirconia] The average particle size of the partially stabilized zirconia was measured using a laser diffraction particle size distribution measuring device "SALD-2300" (manufactured by Shimadzu Corporation). More specifically, 0.15 g of the sample and 40 ml of a 0.2% sodium hexametaphosphate aqueous solution were put into a 50 ml beaker, dispersed for 2 minutes with a tabletop ultrasonic cleaner "W-113" (manufactured by Honda Electronics Co., Ltd.), and then put into the device (laser diffraction particle size distribution measuring device ("SALD-2300" manufactured by Shimadzu Corporation)) for measurement. The results are shown in Table 1.

[0130] [Measurement of Average Particle Size of Zirconium Carbide] The average particle size of the zirconium carbide was measured using a laser diffraction particle size distribution measuring device "SALD-2300" (manufactured by Shimadzu Corporation). More specifically, 0.15 g of the sample and 40 ml of a 0.2% sodium hexametaphosphate aqueous solution were put into a 50 ml beaker, dispersed for 2 minutes with a tabletop ultrasonic cleaner "W-113" (manufactured by Honda Electronics Co., Ltd.), and then put into the device (laser diffraction particle size distribution measuring device ("SALD-2300" manufactured by Shimadzu Corporation)) for measurement. The results are shown in Table 1.

[0131] [Production of Ceramic Sintered Body] Hot press sintering was performed on the ceramic powders of Production Examples 1 to 8 using a 50 mm square die. The sintering conditions were 1350 °C, 1 hour, 40 MPa, and an air atmosphere. Thus, ceramic sintered bodies of Production Examples 1 to 8 were obtained.

[0132] [Table 1]

[0133] [Self-healing confirmation test] (Example 1) The three-point bending strength of the ceramic sintered body of Production Example 1 made into a test piece of 3 mm × 4 mm × 44 mm was measured by the following method. The results are shown in the column of "Before damage" in Table 2. Next, a Vickers indenter was pressed in with a force of 2 kgf to introduce damage. The damage was introduced at the central position (a point 22 mm from each end). The three-point bending strength after introducing damage was measured by the following method. The results are shown in the column of "After damage" in Table 2. Next, heat treatment was performed at 500 °C for 1 hour in a water vapor atmosphere. In Table 2, S indicates that it is "in a water vapor atmosphere". The three-point bending strength after heat treatment (after healing) was measured by the following method. The results are shown in the column of "After healing" in Table 2. In addition, the strength recovery rate (%) was also shown in Table 2. The strength recovery rate (%) was obtained by the following formula. [Strength recovery rate (%)] = ([After healing (MPa)] / [Before damage (MPa)]) × 100

[0134] (Examples 2 to 4, Comparative Examples 1 to 7) Except that the ceramic sintered body used was changed as shown in Table 2 and the heat treatment conditions (healing conditions) were changed as shown in Table 2, the three-point bending strength before damage, the three-point bending strength after damage, and the three-point bending strength after healing were measured in the same manner as in Example 1. Also, the strength recovery rate (%) was determined. The results are shown in Table 2.

[0135] [Three-point bending strength] The three-point bending strength was measured in accordance with the three-point bending strength of JIS R 1601. Note that Examples 1 and 2, Comparative Example 2, and Comparative Example 4 are all sintered bodies using the ceramic powder of Production Example 1, and the three-point bending strength before damage was the same within the error range. Also, the three-point bending strength after damage of Examples 1 and 2, Comparative Example 2, and Comparative Example 4 was the same within the error range. The three-point bending strength after healing differs in value due to differences in the healing conditions.

[0136]

Table 2

Claims

1. Contains zirconium carbide and partially stabilized zirconia, The average particle size of the zirconium carbide is 1 μm or less, The average particle size of the partially stabilized zirconia is 1 μm or less, The content of the zirconium carbide is 15% by volume or more and 40% by volume or less, The ceramic powder is characterized in that the content of the partially stabilized zirconia is 60 volume % or more and 85 volume % or less.

2. The average particle size of the partially stabilized zirconia is 0.7 μm or less, The content of the zirconium carbide is 15% by volume or more and 35% by volume or less, 2. The ceramic powder according to claim 1, wherein the content of the partially stabilized zirconia is 65 volume % or more and 85 volume % or less.

3. The partially stabilized zirconia includes a stabilizer, 3. The ceramic powder according to claim 1, wherein the stabilizer is one or more oxides selected from the group consisting of Y, Ca, Mg, Ce, Yb, Er, and Sc.

4. 4. The ceramic powder according to claim 3, wherein the stabilizer is an oxide of Y.

5. Contains zirconium carbide and partially stabilized zirconia, The average particle size of the zirconium carbide is 1 μm or less, The average particle size of the partially stabilized zirconia is 1 μm or less, The content of the zirconium carbide is 15% by volume or more and 40% by volume or less, The content of the partially stabilized zirconia is 60% by volume or more and 85% by volume or less, A ceramic sintered body, characterized in that a test piece damaged under the following <damage inflicting conditions> and then healed under the following <healing conditions> has a three-point bending strength of 70% or more compared to that before the damage was inflicted. <Damage inflicted conditions> A Vickers indenter is pressed into a test piece of 3 mm x 4 mm x 44 mm with a force of 2 kgf to cause damage. <Cure conditions> The substrate is heat-treated in a water vapor atmosphere at 400° C. for 1 hour.

6. 6. A method for curing a ceramic sintered body, comprising the step of heat treating the ceramic sintered body according to claim 5 in a water vapor atmosphere at 350° C. to 550° C. for 1 hour or more.

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