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, prior to the sintering step, wherein the binder amount of the secondary molding is less than 52 vol.%.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 method for manufacturing a sintered body consisting of a zirconia sintered body containing 2 mol% or more but less than 5 mol% of yttrium, calculated as yttrium. 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 composition of the green body to be subjected to the debinding process affects the debinding behavior. Furthermore, we found that the occurrence of defects in the debinding process can be significantly suppressed by debinding a green body obtained from a ceramic composition (compound) containing a certain amount of binder or less.

[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 for a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium in terms of zirconia oxide equivalent, and a sintering step of sintering a degreased secondary molded body in which the zirconia molded body and the secondary molded body are laminated, the manufacturing method further comprising a degreasing step of degreasing the secondary molded body prior to the sintering step, and the secondary molded body has a binder amount of less than 52 volume %. 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, 2O 3 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. 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 for a zirconia molded body containing 2 mol % or more and less than 5 mol % of yttrium in terms of zirconia oxide equivalent, and a sintering step of sintering a degreased secondary molded body in which the zirconia molded body and the secondary molded body are laminated, the manufacturing method further comprising a degreasing step of degreasing the secondary molded body prior to the sintering step, and the secondary molded body has a binder amount of less than 52 volume %. 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 3The 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 prior to the sintering step. The degreasing step is a step of heat treating the compact (powder compact) to remove the binder. A degreasing step is thus obtained. 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, a secondary molded body having a binder amount of less than 52% by volume is provided. One of the reasons why the yield is improved by degreasing a secondary molded body having a binder amount of less than 52% by volume is thought to be as follows. That is, as the binder amount decreases, the amount of decomposition gas generated by the decomposition of the binder during degreasing decreases. Therefore, deformation and cracking of the degreased body due to the generation of decomposition gas and its detachment from the molded body are less likely to occur. In addition, the reduction in the binder amount suppresses the degree of shrinkage before and after degreasing. As a result, it is thought that deformation of the molded body during degreasing is suppressed.

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

[0015] Degreasing atmosphere: Air or nitrogen 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 degreased body obtained in the above-mentioned degreasing step is used, 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, with the binder content being 50% by volume, 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 29 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 isostatically pressed (HIP) treated, and annealed under the following conditions to obtain the sintered bodies of this example.

[0020] <Pre-sintering> Pre-sintering method:常压烧结 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 Example 2 The degreased body and sintered body of this comparative example were obtained in the same manner as in Example 1, except that a ceramic composition with a binder content of 51 volume % was used and 28 secondary molded bodies were produced.

[0021] Comparative Example 1 The degreased body and sintered body of this comparative example were obtained in the same manner as in Example 1, except that a ceramic composition with a binder content of 52 volume % was used and nine secondary molded bodies were produced.

[0022] 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.

[0023] [Table 1]

[0024] From the above table, it was confirmed that by degreasing a compact with a binder amount of less than 52% by volume, the yield of the degreased body itself is significantly improved, and therefore the yield of the sintered body is also improved. The yield of the sintered body from the degreased body is 100%, and in the manufacturing method of the embodiment, no defects were confirmed to occur during the HIP treatment and the subsequent annealing treatment. In addition, 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, the degreased body obtained by the manufacturing method of Example 1 in which cracks were found only had gaps at 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 for 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 for sintering a degreased secondary molded body in which the zirconia molded body and the secondary molded body are laminated, the manufacturing method further comprising a degreasing step for degreasing the secondary molded body prior to the sintering step, and the secondary molded body has a binder amount of less than 52 volume %. 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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