Setter for firing lithium-containing oxide ceramics

Abstract

To prevent the reaction between lithium contained in the material to be fired and the firing setter. [Solution] In the present invention, a lithium-containing oxide ceramic firing setter for firing lithium-containing oxide ceramics is provided on a mullite substrate or an alumina substrate, the intermediate layer consists of alumina and yttria, or alumina and zirconia, and the surface layer consists of yttria. The intermediate layer consists of 20-80% by weight of alumina, 20-80% by weight of yttria, or 40-80% by weight of alumina and 20-60% by weight of zirconia containing 3-8 mol% yttria. The total thickness of the surface layer and the intermediate layer is 20-150 μm, and the yttria layer, which is the surface layer, is 15 μm or thicker. Protrusions made of yttria with a height of 10-50 μm are scattered on the surface layer at intervals of 100-500 μm.

Description

Technical Field

[0001] The present invention relates to a setter for firing an oxide ceramic compact containing lithium.

Background Art

[0002] Patent Document 1 discloses a firing setter having a coating layer provided on the surface of a base material. The coating layer is provided to suppress the reaction between the fired object and the base material. In Patent Document 1, in order to surely suppress the reaction between the fired object and the base material, two or more coating layers made of different materials are provided on the surface of the base material. In Patent Document 1, two or more spray coating layers, or a thermal spraying layer is provided on the surface of the spray coating layer to form a coating layer.

[0003] Further, in Patent Document 2, a first intermediate layer and a second intermediate layer are provided on a mullite layer, and a yttria layer is formed on the surface layer by coating. The intermediate layer contains silica.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described in Patent Document 1, by providing two or more coating layers on the surface of the substrate, the reaction between the workpiece and the substrate is suppressed, and the workpiece can be fired successfully. However, when firing lithium-containing ceramics, the presence of silica in the intermediate layer makes it impossible to avoid a reaction with the setter even if yttria is provided on the surface layer of the lithium-containing workpiece. Furthermore, if a part of the coating layer peels off due to the reaction with the yttria layer (if delamination occurs between the coating layers), components contained in the substrate move to the workpiece, causing the workpiece to react with the substrate components. In addition, if the yttria layer is less than 15 μm thick, it is not possible to obtain a sound fired workpiece containing lithium, which is the workpiece, if the alumina layer or silica and mullite layer contained in the intermediate layer are not sufficient.

[0006] Furthermore, as described in Patent Document 2, yttria protrusions are provided on the intermediate layer to prevent reaction with the material being fired. However, when firing lithium-containing ceramics, a reaction occurs between the material being fired and the intermediate layer unless the surface layer is completely covered with a material consisting of an yttria layer. [Means for solving the problem]

[0007] Therefore, in the present invention according to claim 1, a lithium-containing oxide ceramic firing setter for firing lithium-containing oxide ceramics is provided on a mullite substrate or an alumina substrate, and the intermediate layer is alumina and yttria, or alumina and Contains 3-8 mol% yttria It is made of one of the following materials, with a surface layer made of yttria. The intermediate layer consists of either 20-80% by weight of alumina and 20-80% by weight of yttria, or 40-80% by weight of alumina and 20-60% by weight of zirconia containing 3-8 mol% yttria, with the total thickness of the surface layer and intermediate layer being 20-150 μm, the yttria surface layer being 15 μm or thicker, and the intermediate layer being 5 μm or thicker. I decided to do that. [Effects of the Invention]

[0012] In the present invention, a firing setter equipped with multiple coating layers for firing lithium-containing oxide ceramics can prevent the reaction between the lithium contained in the material to be fired and the firing setter. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic cross-sectional diagram illustrating the firing setter according to the present invention. [Modes for carrying out the invention]

[0014] As schematically shown in Figure 1, the firing setter according to the present invention has an intermediate layer formed on the upper surface of the substrate, and a surface layer formed on the upper surface of the intermediate layer. An yttria layer is provided in the surface layer. Examples of substrate materials include mullite (mullite layer) and alumina (alumina layer). When the substrate is mullite, the firing setter has a mullite layer (substrate), an intermediate layer provided on the mullite layer, and an yttria layer as the surface layer. When the substrate is alumina, the firing setter has an alumina layer (substrate), an intermediate layer provided on the alumina layer, and an yttria layer as the surface layer. This firing setter, consisting of a composite layer with a three-layer structure, was manufactured by firing at 1500°C.

[0015] For the prepared firing setters, the surface layer, intermediate layer, and substrate were inspected and their thicknesses measured using an energy-dispersive X-ray spectrometer (EDS) attached to a scanning electron microscope (SEM).

[0016] [Examples 1-5] A sheet molded body made of lithium titanate was placed on a firing setter prepared using the composition described in Table 1 and fired at 1300°C. In the workpiece loading reaction test, lithium titanate was applied to the surface of the coating layer (the surface of the firing setter), fired in air at 1200°C for 2 hours, and the presence or absence of a reaction between the coating layer and lithium titanate was visually confirmed. Specifically, the surface of the coating layer after firing was checked, and a reaction was judged to have occurred if melting or peeling was observed in the coating layer. If no reaction was observed visually, it was marked as "◎", if a reaction was observed in an area of ​​10% or less of the test range, it was marked as "〇", and if a reaction was observed in an area of ​​10% or more of the test range, it was marked as "×".

[0017] [Table 1]

[0018] In Examples 1 to 5, when the thickness of the intermediate layer was 5 to 10 μm and the upper yttria layer was 15 to 25 μm, no reaction between the firing setter and lithium titanate as the product was observed, and no delamination of each layer in the firing setter and no warping of the firing setter were observed.

[0019] [Examples 6 to 9] A sheet molded body made of lithium zirconate was placed on a firing setter prepared using the composition described in Table 2 and fired at 1300°C.

[0020] [Table 2]

[0021] In Examples 6 to 9, when the thickness of the intermediate layer was 10 to 15 μm and the upper yttria layer was 15 to 25 μm, no adhesion or reaction between the firing setter and lithium zirconate as the product was observed as shown in the evaluation results, and no delamination of each layer in the firing setter and no warping of the firing setter were observed.

[0022] [Comparative Examples 1 to 4] A sheet molded body made of lithium zirconate was placed on a firing setter prepared using the composition described in Table 3 and fired at 1300°C.

[0023] [Table 3]

[0024] In Comparative Examples 1 to 4, when the thickness of the intermediate layer was 10 to 15 μm and the upper yttria layer was 10 μm or less, adhesion and reaction occurred between the firing setter and lithium zirconate as the product as shown in the evaluation results.

[0025] In Examples 1-9 and Comparative Examples 1-4 described above, experiments were conducted with the substrate changed to mullite. The results showed that when the yttria layer was 10 μm or less, a reaction with the lithium titanate and lithium zirconate molded articles was confirmed.

[0026] Next, to measure the adhesion between the alumina base material and the intermediate and upper layers by varying the addition ratio of alumina + yttria or alumina + yttria-containing zirconia in the intermediate layer, adhesion was evaluated by a peel test using tape. For the peel test, a strong repair tape (Gorilla Tape Black) manufactured by Kure Engineering Co., Ltd. was applied to the surface of the upper layer, and then the tape was peeled off to check the condition of the upper and intermediate layers. If no peeling was observed visually, it was marked as "◎", if peeling of less than 10% of the area was observed visually, it was marked as "〇", and if peeling of 10% or more of the area was observed visually, it was marked as "×".

[0027] [Examples 10-14] In the firing setters prepared using the compositions listed in Table 4 (Examples 10-14), no delamination was observed when the intermediate layer contained alumina + yttria or alumina + yttria-containing zirconia.

[0028] [Table 4]

[0029] [Comparative Examples 5-8] In the firing setters (Comparative Examples 5-8) prepared using the compositions listed in Table 5, delamination was observed in Comparative Example 5 when the amount of alumina added to the intermediate layer was 10%.

[0030] [Table 5]

[0031] In Comparative Examples 6 and 7, when the amount of alumina added to the intermediate layer was 20% and 30%, no delamination was observed when the intermediate composition was alumina + yttria, but delamination was observed when the intermediate layer was alumina + yttria-containing zirconia.

[0032] Furthermore, when the alumina content of the intermediate layer was set to 90%, delamination was observed in both the case of alumina + yttria and alumina + yttria-containing zirconia.

[0033] [Comparative Examples 9-13] Next, a sheet molded body made of lithium titanate was fired at 1300°C using a material consisting of alumina and silica as the intermediate layer.

[0034] In the firing setter containing silica in the intermediate layer prepared using the compositions listed in Table 6, the molded body and the firing setter reacted after firing, causing the lithium titanate molded body to stick to the firing setter and preventing release.

[0035] [Table 6]

[0036] [Examples 10-12] As shown in Table 7, a 3mm thick, 200mm square molded body made of lithium titanate was placed on the firing setter of Examples 1 to 5 and fired at 1300°C, and the maximum warpage of the fired product was measured.

[0037] [Table 7]

[0038] Furthermore, as shown in Table 8, a firing setter was created on top of the firing setter of Example 1, with protrusions of 10 μm (Example 10), 30 μm (Example 11), and 50 μm (Example 12) in height, spaced 200 μm apart. A molded body made of lithium titanate, 3 mm thick and 200 mm square, was placed on each firing setter and fired at 1300°C, and the maximum warpage of the fired product was measured.

[0039] [Table 8]

[0040] The warpage of the fired body was measured using a micrometer to determine the maximum deformation from the bottom surface when the fired body was placed on a flat plate.

[0041] Compared to Examples 1-5 (Table 7), Examples 10-12 (Table 8), which had protrusions, showed significantly less warping. Furthermore, when the size of the protrusions was larger than 50 μm, peeling of the protrusions was observed with increasing firing cycles. Additionally, when the spacing between the protrusions exceeded 500 μm, the deformation increased to over 1 mm.

[0042] The above examples and comparative examples are representative examples, and the following conclusions were reached through other experiments.

[0043] When the base material of the firing setter is made of mullite or alumina, the intermediate layer may consist of 20-80% by weight of alumina and 20-80% by weight of yttria, or 40-80% by weight of alumina and 20-60% by weight of zirconia containing 3-8 mol% yttria.

[0044] As described above, in the setter for firing lithium-containing oxide ceramic molded bodies, the mullite substrate and alumina substrate, which are the base materials, contain the element (Al) that constitutes alumina in the intermediate layer. Therefore, by using alumina + yttria, or alumina + 3-8 mol% yttria-containing zirconia as the intermediate layer, the intermediate layer adheres firmly to the alumina layer or mullite layer, which is the substrate, and also adheres firmly to the yttria layer, which is the upper surface layer. As a result, delamination between the mullite or alumina substrate layer and the intermediate layer, and between the intermediate layer and the yttria layer, is less likely to occur, and the reactivity resistance of the firing setter is improved. Furthermore, by improving the adhesion between each layer, it is possible to suppress the penetration of lithium components contained in the fired product into the coating layer.

[0045] In particular, when yttria is contained in the intermediate and surface layers on a mullite or alumina substrate, the combined thickness of the yttria surface layer and the intermediate layer must be 20 to 150 μm, with the yttria surface layer being at least 15 μm thick. At least the thickness of the yttria surface layer must be at least 15 μm to prevent the reaction between the lithium contained in the fired material and the setter. If the combined thickness of the intermediate and surface layers exceeds 150 μm, delamination may occur due to the difference in thermal expansion with the alumina or mullite substrate.

[0046] By providing yttria-based protrusions on the surface layer of the firing setter, the reaction with the lithium oxide material being fired can be further suppressed, thereby reducing the warping of the lithium oxide material being fired. The height of the protrusions is preferably 10 to 50 μm, and the spacing between the protrusions is preferably 100 to 500 μm. If the height of the protrusions is less than 10 μm, the warping of the material being fired may increase, and if the height of the protrusions exceeds 50 μm, the shape of the protrusions may hinder the shrinkage of the material being fired and induce crack formation. Also, if the spacing between the protrusions is narrower than 100 μm, the warping of the material being fired may increase, and if it is wider than 500 μm, deformation of the material being fired may occur.

Claims

[Claim 1] In a lithium-containing oxide ceramic firing setter for firing lithium-containing oxide ceramics, It is provided on a mullite substrate or an alumina substrate, with an intermediate layer consisting of alumina and yttria, or alumina and zirconia containing 3-8 mol% yttria, and a surface layer consisting of yttria. A lithium-containing oxide ceramic firing setter characterized in that the intermediate layer consists of either 20-80% by weight of alumina and 20-80% by weight of yttria, or 40-80% by weight of alumina and 20-60% by weight of zirconia containing 3-8 mol% yttria, the total thickness of the surface layer and intermediate layer is 20-150 μm, the yttria layer which is the surface layer is 15 μm or thicker, and the intermediate layer is 5 μm or thicker.

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