JP2000185984A - Baking jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically bake a material to be baked having high reactivity with a substrate without any problem by laminating and forming a layer consisting essentially of zirconia particles and a magnesia particle layer to respective specific thicknesses onto the substrate consisting essentially of ceramics such as alumina or mullite. SOLUTION: This baking jig is obtained by baking and forming a layer 2 consisting essentially of zirconia particles to >=20 μm, preferably 20-1,500 μm thickness on a substrate 1 containing >=50 wt.% of ceramics such as alumina, mullite, zirconia, silica, silicon nitride or silicon carbide, then laminating a layer 3 comprising magnesia particles having 0.1-300 μm average particle diameter to >=20 μm, preferably 20-2,000 μm thickness onto the formed layer, baking and forming the resultant laminate. The layer 2 consisting essentially of the zirconia particles consists essentially of the zirconia particles having 0.3-200 μm average particle diameter and contains 1-50 wt.% of one or more kinds of alumina particles having 0.01-500 μm average particle diameter, titania particles having 0.1-500 μm average particle diameter and silica particles having 1-500 μm average particle diameter.

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 and optical materials. 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 jig. 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 have been used in large quantities because they are inexpensive. However, the material to be fired is highly reactive with these materials, forsterite (2MgO.SiO).
₂ ) When sintering a ferroelectric such as lead electronic zirconate titanate (PZT) or the like, a reaction occurs even if a reaction preventing layer using zirconia is present on the surface, and the sintering is performed with the object to be sintered. The jig was fused and the performance of the object to be fired was reduced. In addition, by repeatedly using the firing jig, a reaction between the substrate or the object to be fired and the reaction preventing layer occurs, and a crack or a peeling phenomenon occurs in the reaction preventing layer.

[0003] There has also been a method in which the substrate of the firing jig is made of magnesia without using alumina or mullite. However, the magnesia-based firing jig is weak in thermal shock and weak in hot strength. For this reason, cracking or warpage occurs due to hot use. Among these, a firing jig mixed with coarse aggregate was used to avoid cracking, and a thicker firing jig was used to avoid bending and warping. However, ceramics products containing coarse aggregates are limited to the production method using the vibration casting method, which requires a lot of time and effort.The strength of the resulting product is low, and the surface is rough due to the inclusion of coarse aggregate. It sometimes became a face. Further, increasing the thickness of the firing jig increases the heat capacity, increases the heat consumption for firing, and lacks economy.

[0004]

Conventionally, there is no method for inexpensively producing a firing jig suitable for firing ceramics having high reactivity with alumina or mullite, and the manufacturing is easy. Also, there was no firing jig excellent in durability. This also has a problem in the case where a reaction preventing layer made of zirconia is formed on a firing jig substrate such as alumina or mullite. As means for solving the above problems, Japanese Patent Application No. Hei 8
No. 3,352,798 invented a method of manufacturing a firing jig and a firing jig. In the prior application, there is also a technique of a firing jig having a magnesia particle layer as a surface layer, but there is a problem in durability of a firing jig manufactured using a substrate having a porosity of 20% or less.

[0005]

SUMMARY OF THE INVENTION The invention of this application is intended to manufacture a firing jig capable of firing an object to be fired having high reactivity with alumina or mullite using a substrate having an arbitrary porosity without any problem. However, the following means having a configuration partially different from that of the previous application was used.

The first aspect of the present invention is directed to a method of manufacturing a firing jig. The average particle size of a substrate containing 50% by weight or more of a ceramic selected from alumina, mullite, zirconia, silica, silicon nitride, or silicon carbide is described. The diameter is 0.
Alumina particles having an average particle size of 0.01 to 500 μm, titania particles having an average particle size of 0.1 to 500 μm, and silica having an average particle size of 1 to 500 μm, mainly containing zirconia particles having a particle size of 3 to 200 μm. After forming a layer containing 1 to 50% by weight of one or more of the particles (hereinafter, referred to as a “particle layer containing zirconia particles as a main component”) with a thickness of 20 μm or more, the average particle diameter is 0.1 μm or more. The gist is to form a layer of magnesia particles having a thickness of 1 to 300 μm with a thickness of 20 μm or more.

[0007] Claim 2 shows the structure of the firing jig itself, which is a product manufactured by the method of claim 1, for example, wherein the main ceramics are alumina, mullite,
Zirconia, silica, silicon nitride or silicon carbide,
A layer containing at least one of zirconia particles having a thickness of 20 to 1500 μm as a main component on at least one of the surfaces and containing 1 to 50% by weight of at least one of alumina particles, titania particles, and silica particles; magnesia having a thickness of 20 to 2000 μm; The gist is that the particle layers are sequentially laminated.

A third aspect of the present invention is directed to a ceramic substrate constituting the firing jig according to the second aspect, and has a gist that the porosity is 20% or less.

A fourth aspect of the present invention relates to a ceramic constituting the firing jig according to the second aspect, wherein the substrate, the particle layer mainly composed of zirconia particles, and the magnesia particle layer are fired. The main point is.

In a fifth aspect of the present invention, the ceramic constituting the firing jig according to the second aspect is defined. The substrate is fired, and the particle layer containing zirconia particles as a main component and the magnesia particle layer are unfired. The gist is that the material or the substrate and the particle layer mainly composed of zirconia particles are fired, and the magnesia particle layer is unfired.

According to the present invention, a coating layer composed mainly of zirconia particles, which has a coating layer of magnesia particles on the surface side and acts to prevent the reaction between the substrate and the material to be fired or to reduce the coefficient of thermal expansion. In a layer below the magnesia particle coating layer. By mixing alumina particles, titania particles or silica particles with zirconia particles, the substrate and the particle layer mainly composed of zirconia particles, the particle layer mainly composed of zirconia particles and the magnesia particle layer each have a slight interface. Trigger a reaction,
By increasing the mutual bonding force, peeling due to repeated use is prevented. By the reaction of each interface,
Porosity of 20 which had a problem in repeated use in the prior art
% Of the substrate can significantly improve the durability of the firing jig. The particle layer containing zirconia particles as a main component acts to reduce the coefficient of thermal expansion, suppresses the reaction amount of the magnesia particles on the substrate as compared with the case where the magnesia particles are directly coated and fired, and forms a good single layer of magnesia on the surface. It is possible to hold.

Hereinafter, raw materials or individual means used in the present invention will be described. First, the substrate used in the present invention is easily available and contains at least 50% by weight of ceramics selected from highly versatile alumina, mullite, zirconia, silica, silicon nitride or silicon carbide. Is used.

The porosity indicates the true porosity, and its value is (1)
−bulk specific gravity / true specific gravity) × 100%. The bulk specific gravity used in this equation can be obtained by the Archimedes method, and the true specific gravity can be obtained by finely pulverizing the substrate and using a specific gravity bottle.

In the particle layer containing zirconia particles as a main component, the mixing amount of alumina particles, titania particles or silica particles is preferably 1 to 50% by weight. If the amount is less than 1% by weight, the effect of addition is not obtained, and peeling is likely to occur by repeated use. If the content is 50% by weight or more, the reaction with magnesia particles proceeds, a good single layer of magnesia cannot be maintained on the surface, and the reaction with the material to be fired is not good.

The size of the zirconia particles is such that the average particle size is 0.
3 to 200 μm, the size of alumina particles is 0.01 to 500 μm in average particle size, the size of titania particles is 0.1 to 500 μm in average particle size, and the size of silica particles is 1 to 500 μm in average size. Good to do. If the particle diameter is less than the respective values, sintering of the particles progresses, so that cracks are generated on the surface due to shrinkage, and the particles are easily peeled. vice versa,
If the size exceeds each value, the bonding strength (adhesion) to the substrate is weak, and it is easy to peel off. If the thickness of the particle layer containing zirconia particles as a main component is less than 20 μm, slight segregation of zirconia, alumina, titania, and silica constituting the layer is likely to cause cracking at the time of thermal shock and peeling due to repeated use, and 1500 μm. If it is thicker, peeling due to repeated use is likely to occur, which is not good.

The zirconia to be used as the zirconia particles includes unstable zirconia or a composition obtained by partially or completely stabilizing zirconia with calcia, magnesia, yttria, ceria, or the like. A mixture of a plurality of types may be used.

Examples of the crystal form of alumina used as the alumina particles include α-form, γ-form and θ-form, and these may be used alone or in combination.

Examples of the crystal form of silica used as the silica particles include quartz, cristobalite, tridymite and amorphous, and these may be used alone or in combination.

As the crystal form of titania to be used as the titania particles, a rutile type or an anatase type may be mentioned, and a single kind of these or a mixture of plural kinds thereof may be used.

As a method for forming a particle layer containing zirconia particles as a main component, existing coating techniques such as spray coating, dip coating, or thermal spraying of a slurry in which the particles are dispersed in a solvent such as water are used. It can be done by application.

The magnesia particle layer is one of the reaction preventing layers formed on the outermost surface in the firing jig. The magnesia particles preferably have an average particle size of 0.1 to 300 μm. When the average particle size is less than 0.1 μm, shrinkage stress on the coating surface increases due to sintering during baking, and fine cracks are formed on the surface, and peeling due to repeated use tends to occur. If the thickness is 300 μm or more, the adhesive force cannot be obtained unless the temperature at the time of baking is set to a high temperature or an auxiliary agent is used, and the former is deflected due to the cost and the fire resistance of the substrate, and the separation of the particle layer mainly composed of zirconia particles. This is not good because it must be fired at a firing temperature of 2000 ° C. or higher. Further, since the latter contains impurities as an auxiliary agent, it tends to react with the material to be fired, which is not good.
If the coat layer has no adhesive strength, the rag and the object to be fired are powdery, and require time and labor such as cleaning, which is not very good.
When the thickness of the magnesia particle layer is less than 20 μm, it is not possible to cover the entire lower particle layer composed mainly of zirconia particles, and partially reacts with the material to be fired because the lower layer is exposed, and exceeds 2000 μm. In such a case, peeling due to repeated use is likely to occur. In forming the magnesia particle layer, when the object to be fired is fired using a firing jig, no reaction occurs between the magnesia particle layer and the object to be fired, so that a high-quality product is manufactured.

The magnesia particles have a magnesia purity of 95.
% Is required. When the purity is less than 95% and silica, calcia, alumina or the like is contained as an impurity, it reacts with the material to be fired, which is not good.
The formation of the magnesia particle layer is the same as the formation of the particle layer containing zirconia particles as a main component, for example, painting, dipping,
It can be formed by thermal spraying or the like.

The two layers formed on the surface of the substrate can be used as a firing jig simply by drying after coating. The firing of these ceramic particle layers is performed at 1200 to 2
The temperature range of 000 ° C. is the firing temperature, but is not limited to the case where the coating layer is formed by thermal spraying.

When the firing jig of the present invention is illustrated with reference to the drawings, it has the cross section shown in FIG. In FIG.
FIG. 3 is a cross-sectional view of the firing jig according to claim 2, wherein the substrate 1 is made of a material containing 50% by weight or more of ceramics selected from alumina, mullite, zirconia, silica, silicon nitride, and silicon carbide. A particle layer 2 mainly composed of zirconia particles and a magnesia particle layer are provided on all outer peripheral surfaces. In the firing jig shown in the figure, a plurality of particle layers are formed on both surfaces of the substrate, but this is effective in making the thermal stress applied to the substrate uniform.

Hereinafter, the manufacturing method and the firing jig of the present invention will be described with reference to examples.

[Example 1] Silica in which mullite coexists in corundum
Containing alumina ceramics (SiO ₂: 18%, stoma
Percentage: 10%) as a substrate, complete with 8 moles of yttria
Zirconia particles having a stabilized average particle size of 0.4 μm,
Α-alumina particles having an average particle size of 1.2 μm are weighed 8: 2.
Water was used as a solvent in a ratio to obtain a slurry concentration of 50%.
The substrate was spray-coated on the surface of the substrate. Coat
The thickness of the ring was 80 μm. 98% purity average
Magnesia particles with a particle size of 50 μm
Is dispersed as a solvent to a slurry concentration of 50%,
A particle layer was formed by luconia particles and alumina particles
The surface of the substrate was spray-coated. coating
Had a thickness of 500 μm. Under the condition of 105 ° C
Example of drying for 2 hours and firing at 1450 ° C
It was set to 1.

[0026]

Example 2 Alumina ceramics having a purity of 99% (porosity: 1%) was used as a substrate, and 3 mol of calcia and 2 of yttria were used.
Molar and partially stabilized zirconia particles having an average particle diameter of 10 μm and amorphous silica particles having an average particle diameter of 10 μm are dispersed at a weight ratio of 9: 1 using water as a solvent to obtain a 50% slurry concentration. The substrate was immersed in the slurry for 20 seconds to form a particle layer of zirconia particles and silica particles having a thickness of 150 μm on the substrate surface. After drying in an atmosphere at 105 ° C. for 16 hours, magnesia particles having a purity of 99% and an average particle diameter of 1 μm are dispersed in isobutyl alcohol as a solvent to obtain a slurry concentration of 30%, and a particle layer is formed by zirconia particles and silica particles. The surface of the substrate was spray-coated. The thickness of the coating was 50 μm. This was dried at 105 ° C. for 2 hours and fired at 1450 ° C. to obtain Example 2.

[0027]

Example 3 Silicon Carbide (Purity 92%, Porosity: 15%)
Of the zirconia particles and silica particles used in Example 2 was spray-coated on the surface of the ceramic substrate, and the surface was sprayed to a thickness of 400 μm.
m were obtained. Next, the slurry of magnesia particles used in Example 2 was spray-coated,
Example 3 A magnesia particle layer having a thickness of 100 μm was formed on a substrate on which a particle layer of zirconia particles and silica particles was formed, dried at 105 ° C. for 2 hours, and fired at 1400 ° C. as Example 3.

[0028]

EXAMPLE 4 A ceramic (porosity: 42%) composed of 95% alumina and 5% silica was used as a substrate, and the surface was spray-coated on the substrate using a slurry of a mixture of zirconia particles and silica particles used in Example 2 And
A coating layer having a thickness of 100 μm was obtained. Next, the magnesia particle slurry used in Example 2 was spray-coated to form a 1000 μm-thick magnesia particle layer on the substrate on which the particle layer of zirconia particles and silica particles was formed. Dry for 1 hour
Example 4 was fired at 480 ° C.

[0029]

Example 5 A ceramic (80% porosity: 12%) composed of 80% alumina and 20% silica was used as a substrate, and partially stabilized zirconia particles containing 8 mol of yttria and having an average particle diameter of 30 μm were used. α-alumina particles and rutile-type titania particles having an average particle size of 15 μm
The mixture was mixed at a weight ratio of 1: 2 and sprayed by a plasma spraying apparatus to form a 150 μm layer. Further, magnesia particles having a purity of 99% and an average particle diameter of 50 μm were collected by a similar apparatus for 20 minutes.
Example 5 having a 0 μm layer was formed.

[0030]

Comparative Examples 1 to 4 In Comparative Example 1, ceramics having a thickness of 20 mm and made of calcined magnesia particles having a purity of 95% and an average particle diameter of 5 μm were used as a firing jig. In Comparative Example 2, magnesia particles having a purity of 95% and having an average particle size of 5 μm and 3 mm were mixed at a weight ratio of 1: 1 and fired, and a 10 mm thick ceramic was used as a firing jig. In Comparative Example 3, a slurry of a mixture of zirconia particles and silica particles used in Example 2 was applied to a 5 mm-thick substrate made of alumina ceramic having a purity of 99% (porosity: 1%) in the same manner as in Example 2. It was applied by a method to obtain a particle layer of 150 μm thick zirconia particles and silica particles. This was fired at 1450 ° C. and used as a firing jig. In Comparative Example 4, the slurry of magnesia particles used in Example 2 was applied to a 5 mm-thick substrate made of alumina ceramic having a purity of 99% (porosity: 1%) by the same method, and the magnesia particles having a thickness of 50 μm were applied. Layer obtained. This was fired at 1450 ° C. and used as a firing jig.

[0031]

Comparative Examples 5 to 12 Comparative Example 5 As Comparative Example 12, a firing jig having a particle layer containing zirconia particles as a main component or a magnesia particle layer shown in Table 1 was prepared. As the substrate, the same silica-containing alumina ceramics as in Example 1 (SiO ₂ : 18%, porosity: 10%) was used.
The firing temperature was 1450 ° C. 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. In Comparative Examples 5 and 6, the same slurry as the mixture of zirconia particles and silica particles used in Example 2 was used. In Comparative Examples 7 and 8, the slurry of magnesia particles used in Example 2 was used. The same as was used. In Comparative Examples 9 and 10, the same slurry as the mixture of zirconia particles and alumina particles used in Example 1 was used. In Comparative Example 11, the slurry of the mixture of zirconia particles and silica particles used in Example 2 was used. The same slurry as the magnesia particles was used.

[0032]

[Table 1]

[0033]

Comparative Example 13 In Comparative Example 13, the magnesia particle in the magnesia particle layer used in Example 3 had a purity of 90%.
A sintering jig was prepared using a material containing silica (SiO ₂ ), calcia (CaO), and diiron trioxide (Fe ₂ O ₃ ) as other components. In addition, the substrate, the slurry of the mixture of the zirconia particles and the silica particles, and the method of applying the slurry were all the same as in Example 3.

[0034]

Comparative Example 14 and Comparative Example 15 In Comparative Example 14, a mixture of zirconia particles (average particle diameter 50 μm) and calcia having an average particle diameter of 20 μm in a weight ratio of 9: 1 was used.
In No. 5, a mixture of zirconia particles and barium carbonate (BaCO ₃ ) having an average particle diameter of 200 μm in a weight ratio of 7: 3 was used, and the coating was performed by the same method and thickness as in Example 1.
In addition, in Comparative Examples 14 and 15, the substrate, the particle size of the zirconia particles, the particle size of the magnesia particles, the coating thickness, the firing conditions, and the like were all the same as those in Example 1.

[0035]

Comparative Examples 16 to 18 In Comparative Example 16, the purity was 99%.
% Alumina ceramic (porosity 10%) as a substrate,
Only unstable zirconia having an average particle size of 150 μm is dispersed using water as a solvent to obtain a slurry having a 50% slurry concentration.
Spray coating with a thickness of 0 μm, and further Example 1
The same slurry as the magnesia particles used in the above was applied in a similar manner to a thickness of 150 μm, and baked under the same conditions as in Example 1. In Comparative Example 17, alumina ceramic having a purity of 99% (porosity: 20%) was used as the substrate. In Comparative Example 18, alumina ceramic having a purity of 99% (porosity: 40%) was used.
Was used as a substrate. In both Comparative Examples 17 and 18, the slurry used in the coating, the amount of coating, and the firing conditions were the same as in Comparative Example 16.

[0036]

[Comparative test] The above Examples 1 to 5 and Comparative Examples 1 to 5
The firing jig according to Comparative Example 18 was used as a shelf board, and an electronic component having a composition of PZT was placed on them, and a test in which the temperature was repeatedly increased and decreased according to the same temperature curve as that actually used was a problem. A confirmation test was performed until the occurrence of, or whether 100 repetitions were possible. In Example 1 to Example 5, no problem occurred in the firing jig or the object to be fired even when the test was repeated 100 times. Table 2 shows the results of Comparative Examples 1 to 18.

[0037]

[Table 2]

The number of abnormal occurrences in Table 2 indicates an abnormal occurrence cycle in one or two of the check items such as warpage / bending, crack, peeling, ragging, and reaction / fusion. . Therefore, the blank part was blank because tests after the number of cycles in which an abnormality occurred were omitted.

For the types of abnormalities shown in Table 2,
Deflection means that the firing jig is in a state of being bent, sagged, and rattled. A crack refers to a state in which the magnesia particle layer or another reaction preventing layer of the firing jig has cracks. Peeling refers to the state in which voids are formed between the substrate and the particle layer containing zirconia as a main component, or between the particle layer containing zirconia as a main component and the magnesia particle layer, or the state where the puffy layer is peeled off. To tell.
The rag is a firing jig in which particles forming the magnesia particle layer or other reaction preventing layer are shed and the particles are attached to the object to be fired, so that shedding proceeds. The term "reaction / fusion" refers to a state in which the object to be fired and the firing jig react with each other and are fused.

In all the examples, a firing test for repeating the firing of the object to be fired was repeated up to 200 times.
In Example 4, cracks or peeling were partially observed around the shelf plate after about 150 passes, but no abnormalities were observed in other Examples.

[0041]

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 material to be fired, so that 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 particle layer mainly composed of zirconia particles and a magnesia particle layer are sequentially formed on a substrate.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 particle layer mainly composed of zirconia particles 3 magnesia particle layer

Claims (5)

[Claims] An average particle size of a substrate containing 50% by weight or more of a ceramic selected from alumina, mullite, zirconia, silica, silicon nitride, and silicon carbide is 0.3%.
Alumina particles having an average particle size of 0.01 to 500 μm, titania particles having an average particle size of 0.1 to 500 μm, or silica having an average particle size of 1 to 500 μm After forming a layer containing 1 to 50% by weight of one or more kinds of oxides arbitrarily selected from the particles with a thickness of 20 μm or more, magnesia particles having an average particle diameter of 0.1 to 300 μm are used. A method for manufacturing a firing jig, wherein the layer is formed with a thickness of 20 μm or more. 2. The main ceramic of the substrate is alumina,
It is arbitrarily selected from mullite, zirconia, silica, silicon nitride, or silicon carbide, and has zirconia particles as a main component on one or more of its surfaces and an average particle size of 0.01 or more.
Alumina particles having a mean particle size of 0.1 to 500 μm
Titania particles at 500 μm, or an average particle size of 1 to
A layer composed of particles containing a mixture containing 1 to 50% by weight of one or more oxides arbitrarily selected from silica particles having a thickness of 500 μm, a layer having a thickness of 20 to 1500 μm, and a magnesia particle having a thickness of 20 to 2000 μm. A firing jig, wherein the layers are sequentially laminated. 3. The porosity of the substrate according to claim 2 is 20%.
A firing jig characterized by the following. 4. The firing jig according to claim 2, wherein the substrate, the particle layer mainly composed of zirconia particles, and the magnesia particle layer are fired. 5. A substrate wherein the substrate is fired and the particle layer mainly composed of zirconia particles and the magnesia particle layer are unfired.
4. The firing jig according to claim 2, wherein the substrate and the particle layer containing zirconia particles as main components are fired, and the magnesia particle layer is unfired. 5.