Method for manufacturing sintered compact

Abstract

To provide a method for manufacturing a sintered compact that is composed of a sintered compact of zirconia containing titanium and 5 mol% or more and 10 mol% of yttrium in terms of Y2O3, and a sintered compact of zirconia containing a complex oxide of iron and cobalt and titanium, and 2 mol% or more and less than 5 mol% of yttrium in terms of Y2O3, as an opaque zirconia part, which can suppress lowering of a yield.SOLUTION: A method for manufacturing a sintered compact that is composed of a sintered compact of zirconia containing titanium and 5 mol% or more and 10 mol% of yttrium in terms of Y2O3, and a sintered compact of zirconia containing a complex oxide of iron and cobalt and titanium, and 2 mol% or more and less than 5 mol% of yttrium in terms of Y2O3 including a sintering step of sintering a degreased body of a secondary molding in which a molding of zirconia containing titanium and 5 mol% or more and 10 mol% of yttrium in terms of Y2O3, and a molding of zirconia containing a complex oxide of iron and cobalt and titanium, and 2 mol% or more and less than 5 mol% of yttrium in terms of Y2O3 are stacked, includes a degreasing step of degreasing the secondary molding in a nitrogen atmosphere and forming the degreased secondary molding into a degreased body, prior to the sintering step.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a method for producing a sintered body. [Background technology]

[0002] As a zirconia sintered body that can be used in a wider range of applications than conventional ceramic joints containing transparent zirconia, a zirconia sintered body having a transparent zirconia part and a zirconia part and having a biaxial bending strength of 300 MPa or more is known (Patent Document 1). In Patent Document 1, the transparent zirconia part contains titanium and Y 2 O 3 The zirconia sintered body contains 10 mol % of yttrium in terms of yttrium, and the opaque zirconia portion contains a composite oxide of iron and cobalt and titanium, and Y 2 O 3 A sintered body made of zirconia containing 4 mol % of yttrium converted therein is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-121576 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the sintered body of Patent Document 1 was prone to defects when repeatedly produced, resulting in a low final yield.

[0005] In the present disclosure, titanium is included, and Y 2 O 3 A sintered body of zirconia containing 5 mol% to 10 mol% of yttrium in terms of yttrium conversion, and an opaque zirconia portion containing a composite oxide of iron and cobalt and titanium, 2 O 3The present invention aims to provide a method for producing a sintered body made of zirconia containing 2 mol % or more and less than 5 mol % of yttrium, calculated as a yttrium content, capable of suppressing a decrease in yield. [Means for solving the problem]

[0006] In the present disclosure, titanium is included, and Y 2 O 3 A sintered body of zirconia containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3 We investigated a manufacturing method for a sintered body made of zirconia containing 2 mol% or more but less than 5 mol% yttrium in terms of yttrium content. As a result, we found that the yield in the debinding process has a large effect on the yield of the final sintered body, and that the debinding atmosphere affects the debinding behavior. In addition, we found that the air atmosphere promotes the generation of defects during debinding. Furthermore, we found that the generation of defects in the debinding process can be significantly suppressed by controlling the atmosphere during debinding.

[0007] That is, the present invention is as described in the claims, and the gist of the present disclosure is as follows. [1] Contains titanium, Y 2 O 3 A zirconia molded body containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3 A manufacturing method including a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium in terms of yttrium converted into titanium, and a sintering step of sintering a degreased body of a secondary molded body in which the zirconia molded body and the secondary molded body are laminated, the method comprising the steps of: degreasing the secondary molded body in a nitrogen atmosphere prior to the sintering step; 2 O 3 A sintered body of zirconia containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3A method for producing a sintered body made of zirconia containing 2 mol % or more and less than 5 mol % of yttrium, calculated as yttrium content. Effect of the Invention

[0008] According to the present disclosure, titanium and Y 2 O 3 A sintered body of zirconia containing 10 mol % of yttrium in terms of yttrium, a composite oxide of iron and cobalt, and titanium, and Y 2 O 3 It is possible to provide a manufacturing method capable of suppressing a decrease in yield in a manufacturing method for a sintered body made of a zirconia sintered body containing 4 mol % of yttrium in terms of converted value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The manufacturing method of the present disclosure will be described below with reference to an example embodiment. The present disclosure includes any combination of the configurations and parameters disclosed herein, and also includes any combination of the upper and lower limits of the values ​​disclosed herein.

[0010] This embodiment includes titanium, Y 2 O 3 A zirconia molded body containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3 A manufacturing method including a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium in terms of yttrium converted into titanium, and a sintering step of sintering a degreased body of a laminated secondary molded body, characterized in that a degreasing step of degreasing the secondary molded body in a nitrogen atmosphere to obtain a degreased body is included prior to the sintering step. 2 O 3 A sintered body of zirconia containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3 The present invention relates to a method for producing a sintered body made of zirconia containing 2 mol % or more and less than 5 mol % of yttrium, calculated as yttrium content.

[0011] The molded body to be subjected to the sintering step contains titanium and Y 2 O 3 A zirconia molded body containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3 The secondary molded body is a degreased body of a laminate of a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium in terms of yttrium content (hereinafter, simply referred to as "secondary molded body"). The secondary molded body contains a binder to improve its moldability and shape retention. The secondary molded body is subjected to a degreasing process prior to the sintering process, whereby the binder is removed from the secondary molded body, i.e., the secondary molded body is a so-called degreased body.

[0012] The manufacturing method of this embodiment includes a degreasing step of degreasing the secondary compact in a nitrogen atmosphere prior to the sintering step. The degreasing step is a step of heat treating the compact (powder compact) to remove the binder. A degreased body is obtained as a result. Therefore, the secondary compact to be subjected to the degreasing step contains titanium and Y. 2 O 3 A zirconia molded body containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, 2 O 3 The molded body is laminated with a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium, calculated as yttrium content, and further contains a binder.

[0013] In the degreasing step in this embodiment, the degreasing atmosphere is a nitrogen atmosphere. The following is one of the reasons why the yield is improved by using a nitrogen atmosphere as the degreasing atmosphere. That is, the conventional degreasing step, including Patent Document 1, is performed in an air atmosphere. However, degreasing in an air atmosphere causes thermal oxidative decomposition due to the reaction between the binder and oxygen. In contrast, degreasing in a nitrogen atmosphere does not cause thermal oxidative decomposition. Since thermal oxidative decomposition is an exothermic reaction, localized heat is generated throughout the secondary molded body during the thermal oxidative decomposition, which rapidly promotes localized reactions such as further volatilization and decomposition of the binder. As a result, it is thought that defects such as cracks occur starting from the occurrence of localized reactions.

[0014] The conditions for the degreasing step include the following.

[0015] Heating rate: 0.5℃ / hour to 200℃ / hour Degreasing temperature: 150℃ or higher and 800℃ or lower The holding time at the debinding temperature may be appropriately adjusted depending on the shape and size of the molded body to be subjected to the debinding step and the characteristics of the heat treatment furnace to be used, and may be, for example, from 0.5 hours to 5 hours.

[0016] For the sintering in the sintering step, any known sintering method can be applied except that the secondary molded body (degreased body) obtained in the above-mentioned degreasing step is provided, and it is preferable to apply the sintering method disclosed in Patent Document 1. EXAMPLES

[0017] The present disclosure will be described below with reference to examples. However, the present disclosure is not limited to the following examples.

[0018] Example 1 A ceramic composition containing 5.5 mol% yttrium-containing zirconia powder (product name: Zpex-smile, manufactured by Tosoh Corporation) and a binder was injection-molded under the condition of an injection pressure of 120 MPa to obtain a cylindrical molded body with a diameter of 10 mm and a height of 10 mm (green compact; injection-molded body). Next, a ceramic composition containing 4 mol% yttrium-containing zirconia powder (product name: Zpex4.m, manufactured by Tosoh Corporation) and a binder was injection-molded under the condition of an injection pressure of 120 MPa so as to cover the periphery of the primary molded body, and a cylindrical molded body with a diameter of 40 mm and a height of 10 mm (green compact; injection-molded body) was obtained. The same operation was repeated to produce 9 secondary molded bodies. The obtained secondary molded bodies were each heat-treated (debound) under the following conditions to obtain the debound bodies of this example.

[0019] Debinding atmosphere: Nitrogen atmosphere Heating rate: 5 °C / hour Debinding temperature: 450 °C Holding time: 2 hours The obtained debound bodies were each pre-sintered, hot isostatic pressing (HIP) treated, and annealed under the following conditions to obtain the sintered bodies of this example.

[0020] <Pre-sintering> Pre-sintering method: Normal pressure sintering Atmosphere: Air atmosphere Heating rate: 100 °C / hour Pre-sintering temperature: 1350 °C Holding time: 2 hours <HIP treatment> Atmosphere: Argon atmosphere Heating rate: 600 °C / hour HIP treatment temperature: 1525 °C Holding time: 1 hour <Annealing treatment> Atmosphere: Air atmosphere Heating rate: 100 °C / hour Annealing temperature: 900 °C Holding time: 1 hour Comparative Example 1 A degreased body and a sintered body of this comparative example were obtained in the same manner as in Example 1, except that the degreasing atmosphere was air.

[0021] The obtained degreased and sintered bodies were visually inspected, and cracks and interfacial cracks between the two materials were regarded as defects, and the percentage of defect-free pieces out of the total number produced was regarded as the yield. The results are shown in the table below.

[0022] [Table 1]

[0023] From the above table, it was confirmed that the yield of the degreased body itself was significantly improved by degreasing in a nitrogen atmosphere, and this also improved the yield of the sintered body. The yield of the sintered body from the degreased body was 100%, and in the manufacturing method of the embodiment, no defects were confirmed to occur during the HIP treatment and the subsequent annealing treatment. Furthermore, by visual inspection, the degreased body obtained by the manufacturing method of Comparative Example 1 had many cracks that crossed the degreased body. In contrast, in the degreased body obtained by the manufacturing method of Example 1, cracks were found only at the level of a gap occurring in a part of the interface between the two materials, and it was confirmed that even in the degreased body in which defects occurred, the defects themselves were smaller than those in the comparative example.

Claims

【Claim 1】 Contains titanium, Y ２ O ３ A zirconia molded body containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, ２ O ３ A manufacturing method including a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium in terms of yttrium conversion and a sintering step of sintering a degreased body of a secondary molded body laminated with zirconia, characterized in that a degreasing step of degreasing the secondary molded body in a nitrogen atmosphere prior to the sintering step is included. ２ O ３ A sintered body of zirconia containing 5 mol % or more and 10 mol % or less of yttrium converted into yttrium, a composite oxide of iron and cobalt, and titanium, ２ O ３ A method for producing a sintered body made of zirconia containing 2 mol % or more and less than 5 mol % of yttrium converted into yttrium.

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