JPH11199312A - Baking jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a jig for baking a highly reactive or fusible to-be-baked object by forming a coating layer of rare earth metal oxide on a base material containing a specific amount or greater of ceramic(s) selected from alumina, mullite, zirconia, silica, silicon nitride and silicon carbide. SOLUTION: This baking jig is obtained by forming 21 coating layer of rare earth metal oxide >=30 μm in thickness on a base material containing >=50 wt.% of ceramic(s) selected from alumina, mullite, zirconia, silica, silicon nitride and silicon carbide. Another version of this baking jig is obtained by forming a reaction-proofing layer 0.3-200 μm in central particle size and <=500 μm in thickness consisting mainly of ceramic(s) selected from alumina, magnesia, titania, zirconia, calcia and zinc oxide followed by a coating layer consisting of the above rare earth metal oxide on a base material; wherein the rare earth metal oxide is e.g. yttrium oxide, gallium oxide, dysprosium oxide, and powdery particles of the oxide 0.5-100 μm in central size are used as the coating layer in a coating material fashion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a setter used for firing ceramics having high reactivity with alumina, silica or zirconia among ceramics used for electronic materials, biomaterials, industrial materials, optical materials and the like. And shelf boards.

[0002]

2. Description of the Related Art Conventionally, when a ceramic product such as an electronic material is fired in a furnace, a firing jig such as a setter or a shelf board is used, and firing and sintering are performed by mounting the jig on the set. Had been These firing jigs, which are selected from alumina, mullite, silicon carbide or silicon nitride, can be used in a high-temperature oxidizing atmosphere and are inexpensive, so that they are used in large quantities. However, forsterites (2MgO.Si
O ₂ ) electronic components, lead zirconate titanate (PZT)
When firing a ferroelectric substance such as or a product containing a component that melts during firing or having a surface coated with a molten component, such as foamed glass or glass, when sintering a substrate coated with zirconia, Even if the reaction prevention layer used is present, a reaction occurs, and the object to be fired and the firing jig are fused,
The performance of the material to be fired was reduced. In addition, the repeated use of the firing jig causes a reaction between the substrate or the object to be fired and the reaction preventing layer, thereby causing the reaction preventing layer to undergo cracking and peeling phenomena.

[0003] There has been a method in which the substrate of the firing jig is made of magnesia without using alumina or mullite. However, a firing jig made of magnesia is weak in thermal shock and weak in hot strength. Cracking due to heat or bending and warping due to hot use occur. Of these, a firing jig mixed with coarse aggregate is used to avoid cracking, and the firing jig is thickened to avoid bending and warping. That was done.
However, ceramic products containing coarse aggregates are limited to the vibration molding method, and the production method is time-consuming. The resulting product also has low strength and the surface is coarse aggregate. The rough surface and the large thickness of the firing jig increased the heat capacity, and therefore increased the heat consumption for firing, resulting in lack of economy. Further, if boron nitride or carbon is used, fusion to glass or the like can be prevented, but the use condition is 900 ° C. in an oxidizing atmosphere.
Below, its application range was limited.

[0004]

Conventionally, there is no method for inexpensively producing a firing jig suitable for firing ceramics having high reactivity or fusion with alumina or mullite. There was no firing jig that was easy to manufacture and had excellent durability. This also has a problem in the case where a reaction preventing layer made of zirconia is formed on a firing jig substrate made of alumina or mullite.

[0005]

According to the invention of this application, there is provided a firing jig capable of firing an object to be fired having high reactivity or fusion with alumina or mullite without any problem. In order to produce a high object to be fired, the following means were used.

[0006] The invention of claim 1 specifies a component constituting a firing jig, and the invention of claim 2 is an invention using the firing jig according to claim 1.

[0007] The invention of claim 1 is characterized in that the invention is composed of a fired product of a rare earth oxide.
The gist of the invention is that the work is fired using a firing jig made of a fired product of the rare earth oxide.

[0008] The inventions of claims 3 to 6 are a group of inventions in which the rare earth oxide is constituted as a coating layer of a firing jig, and the invention of claim 7 is described in claims 3 to 6. It is an invention for utilizing one of the firing jigs.

According to a third aspect of the present invention, a coating layer made of a rare earth oxide is formed on a base material containing at least 50% by weight of a ceramic selected from alumina, mullite, zirconia, silica, silicon nitride or silicon carbide. The gist is that

[0010] The invention of claim 4 or 5 is more specific for the coating layer in the invention of claim 3,
Claim 4 uses an unfired particle layer of a rare-earth oxide, and claim 5 points out that the fired layer of the rare-earth oxide is a coating layer.

[0011] The invention according to claim 6 is characterized in that alumina, mullite,
For a base material containing 50% by weight or more of ceramics selected from zirconia, silica, silicon nitride, or silicon carbide, first, an oxide selected from alumina or magnesia, titania, zirconia, calcia, zinc oxide, or the like is used. The gist is that a reaction prevention layer and secondly, a rare earth oxide coating layer are formed.

According to a seventh aspect of the present invention, a workpiece is fired using a firing jig having alumina or mullite as a base material and having a coating layer of a rare earth oxide. The gist is to do.

In the present invention, as a basic technique, a rare earth oxide is used for the contact surface of the firing jig with the work. Conventionally, rare earth oxides include a reaction prevention layer formed on the surface of a firing jig, and yttria as a stabilizer added to zirconia which is a main component used in the reaction prevention layer. However, there was no technical idea about using a rare earth oxide as a base material of a firing jig or using it as a reaction preventing layer. Hereinafter, individual elements constituting the present invention will be described.

The rare earths referred to in the present invention are 15 elements from lanthanum of atomic number 57 to lutetium of number 71, also called rare earth, and scandium of number 21. 3
It refers to the 9th yttrium. When the rare earth is converted to oxide, yttrium oxide (yttria, Y
₂ O ₃ ), cerium oxide (ceria, CeO ₂ ), neodymium oxide (Nd ₂ O ₃ ), samarium oxide (Sm
₂ O _3), gadolinium oxide _{(Gd 2 O} 3), and the like dysprosium oxide _(Dy 2 _{O 3).} Among these oxides, yttrium oxide, gadolinium oxide, and dysprosium oxide are particularly excellent in terms of practical availability in view of availability, low cost, and stability when mixed with water. These rare earth oxides can be used alone or in combination of two or more.

When the coating layer is formed by a rare earth oxide, powder particles are used in the form of a paint. As for the size of the particles, the center particle size is preferably 0.5 to 100 μm.
If it is less than 0.5 μm, a solid-phase reaction with the substrate is likely to occur,
A reaction layer is formed up to the surface, and does not become a reaction prevention layer with the fired product. Further, the sintering of the rare earth elements easily progresses, and cracks and peeling occur due to shrinkage of the coating layer, which is not good. 1
When particles having a size of more than 00 μm are used, the bonding strength with the substrate is weak, and the particles fall off and adhere to the product, or the coating layer gradually disappears, which is not good.

The coating layer of the rare earth oxide has a thickness of 3
It is preferable that the thickness is formed at 0 μm or more. When the thickness of the coating layer is less than 30 μm, the reaction layer with the base material extends to the surface and reacts with the fired product, which is not good.
Conversely, it is also possible to increase the thickness so that the entire thickness of the firing jig is made of a rare earth oxide. However, if the cost of the firing jig is to be reduced, the thickness of the coating layer should be 500 μm or less. It is economical to do so. On the other hand, when the coating thickness is increased, peeling tends to occur due to the difference in the coefficient of thermal expansion due to repeated use, which is not good.

When a rare earth oxide is used as a coating layer of a firing jig, a reaction preventing layer mainly composed of a ceramic selected from alumina, magnesia, titania, zirconia, calcia or zinc oxide, which is conventionally present, is provided inside the coating layer. It is also possible to form. The reaction preventing layer on the surface of the firing jig is made of particles of the above-mentioned alumina or the like, having a central particle size of 0.3 to 0.3.
An object having a thickness of 200 μm is formed so as to have a thickness of 500 μm or less. Thereafter, the rare earth oxide coating layer, which is a feature of the present invention, is coated with the thickness described above, that is, 30 μm.
m or more. Incidentally, this reaction preventing layer deteriorates productivity, but it is also possible to form a multilayer such as a lamination of a coating layer of alumina and a coating layer of zirconia.

When the firing jig according to the present invention is illustrated with reference to the drawings, what is equivalent to claim 1 is a homogeneous one, and therefore is omitted, and FIG. 1 or FIG. FIG. 3 or FIG. 4 shows a cross section of the layer where the layer is formed, and FIG. 3 or FIG.

1 and 2, a coating layer 2 made of a rare earth oxide is provided on the outer peripheral surface of a substrate 1 made of ceramics selected from alumina, mullite, zirconia, silica, silicon nitride or silicon carbide. ing. 3 and 4, the substrate 1 is made of alumina,
A firing jig having a reaction-preventing layer mainly composed of ceramics selected from zirconia, titania, zirconia, calcia or zinc oxide, and a coating layer made of a rare earth oxide as an outer layer. The other reference numerals 1 and 2 are the same as those in FIG. In the firing jig shown in the figure, a plurality of coating layers are formed on both surfaces of the substrate, but this is effective in making the thermal stress applied to the substrate uniform.

[0020]

EXAMPLES The production method and the firing jig of the present invention will be described below with reference to examples. Example 1 Commercially available yttrium oxide powder (purity: 99.9%, central particle size: 1 μm) was wet-mixed in ethanol containing 60 wt% for 24 hours, and then granulated to about 50 μm with a spray drier. Cold isostatic press molding (CIP) was performed at a pressure of cm ² to obtain a molded body of 100 × 100 × 5 mm. This was fired at 1600 ° C. in the air to obtain a product.

Example 2 and Example 3 In Example 2, a silica-containing alumina ceramic (18% SiO ₂ ) in which mullite coexists in corundum was used as a substrate, having a purity of 99.8% and a center particle size of 1.5 μm. One part by weight of a surfactant was added to 100 parts by weight of yttrium oxide particles, and the resultant was immersed in a dispersion of 50% slurry in water for 20 seconds to form a 130 μm yttrium oxide particle layer on the substrate surface. Was. Example 2 was dried at 105 ° C. for 2 hours. Example 3 refers to Example 2 fired at 1450 ° C.

Examples 4 and 5 A partially stabilized zirconia particle containing 3 moles of calcia and 2 moles of yttrium oxide and a center particle size of 10 μm were dispersed in water as a solvent, and 50% was dispersed in alumina ceramic having a purity of 99% as a substrate. A slurry having a slurry concentration was prepared, and the substrate was immersed in the slurry for 20 seconds.
Of zirconia particles was formed. It was dried in an atmosphere of 105 ° C. for 16 hours and fired at 1450 ° C.
The substrate having the zirconia particle layer has a purity of 99%.
%, A 30% slurry of neodymium oxide particles having a center particle diameter of 1 μm dispersed in isobutyl alcohol was spray-coated to form a 50 μm-thick neodymium oxide particle layer, and dried for 24 hours. Example 4 is a firing jig for an alumina substrate having a zirconia particle layer and a neodymium oxide particle layer on its surface. The fifth embodiment is different from the fourth embodiment in that
It is fired at 450 ° C.

Example 6 In Example 6, a ceramic of silicon carbide (92% purity) was used as a substrate, and the slurry of the zirconia particles used in Example 4 was spray-coated on the surface of the ceramic to form a coating having a thickness of 300 μm. Layer obtained. Next, a slurry in which the yttrium oxide particles used in Example 2 were dispersed was spray-coated to form a 100 μm-thick yttrium oxide particle layer on the substrate on which the zirconia layer was formed, and dried for 24 hours. Was. Then, it was baked at 1450 ° C.

In Comparative Example 1, partially stabilized zirconia particles containing 3 mol of calcia and 2 mol of yttrium oxide, and a center particle diameter of 10 μm were dispersed in water as a solvent on a 5 mm thick substrate made of alumina ceramics having a purity of 99%. A 50% slurry concentration was prepared, and the substrate was immersed in the slurry for 20 seconds to form a 150 μm zirconia particle layer on the substrate surface. It was dried in an atmosphere at 105 ° C. for 16 hours and fired at 1450 ° C.

Comparative Example 2 Hereinafter, in Comparative Example 7, a firing jig having a zirconia particle layer or a yttrium oxide particle layer shown in Table 1 below was prepared. Example 2
Silica-containing alumina ceramics (SiO ₂ 18
%). Further, in these comparative examples, the particle diameter of the particles to be coated or the thickness to be coated is changed, but the composition is the same as that used in the examples. The yttrium oxide particles used in Comparative Examples 4 to 7 were the same as those in Example 2.
And the zirconia particles used in Comparative Example 7 are the same as those used in Example 4.

[0026]

[Table 1]

Comparative Tests The firing jigs of Examples 1 to 6 and Comparative Examples 1 to 7 were used as shelves, and the composition was P
An electronic component made of ZT was placed, and a test in which the temperature was raised and lowered repeatedly according to the same temperature curve as that actually used, and a confirmation test was performed until a problem occurred or whether it could be repeated 50 times. . In Examples 1 to 6, no problem occurred in the firing jig or the object to be fired even after the test was repeated 50 times. The results in Comparative Examples 1 to 6 are shown in Table 2 below.

[0028]

[Table 2]

With respect to the examples, firing tests of the 51st and subsequent times were performed about 100 times. In Example 1, no abnormality was found even after 100 tests. In Example 3, a part to be partially fused was formed at the 81st time.
There was no problem until 00 cycles. In the fifth embodiment, 62
The substrate cracked the first time. The coating was fine.
In Example 6, there was no abnormality at all in 100 tests.

[0030]

The firing jig of the present invention can be used when firing a ceramic product having high reactivity with alumina, the manufacturing method is easy, and the cost can be reduced. Further, even when used, it can withstand repeated use and does not cause a problem in the quality of the object to be fired, and the heat consumption in the firing step can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a firing jig in which a coating layer made of a rare earth oxide is formed on a substrate.

FIG. 2 is a sectional view showing an example of a firing jig in which a coating layer made of a rare earth oxide is formed on a substrate.

FIG. 3 is a cross-sectional view showing an example of a firing jig in which a reaction preventing layer selected from alumina or the like and a coating layer made of a rare earth oxide are sequentially formed on a substrate.

FIG. 4 is a cross-sectional view showing an example of a firing jig in which a reaction prevention layer selected from alumina or the like and a coating layer made of a rare earth oxide are sequentially formed on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Coating layer 3 Reaction prevention layer

Claims (7)

[Claims] 1. A firing jig comprising a fired rare earth oxide. 2. A method for using a firing jig, wherein the work is fired using the firing jig according to claim 1. 3. A coating layer comprising a rare earth oxide is formed on a substrate containing at least 50% by weight of a ceramic selected from alumina, mullite, zirconia, silica, silicon nitride or silicon carbide. And firing jig. 4. A firing jig, wherein the coating layer according to claim 3 is an unfired particle layer of a rare earth oxide. 5. A firing jig, wherein the coating layer according to claim 3 is obtained by firing a rare earth oxide. 6. A base material containing at least 50% by weight of a ceramic selected from alumina, mullite, zirconia, silica, silicon nitride or silicon carbide, is firstly made of alumina or magnesia, titania, zirconia, calcia, zinc oxide. A firing jig characterized by having a reaction prevention layer made of an oxide selected from the group consisting of a rare earth oxide and a second layer. 7. A method of using a firing jig, wherein the work is fired using the firing jig according to claim 3, claim 4, claim 5, or claim 6.