JP2000211976A - Burning of electronic ceramic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To homogeneously sinter a large-scaled ceramic compact by scattering reaction-preventing powder such as alumina, beryllia, magnesia or zirconia on a waste plate formed with the same materials as an object to be burnt and subjected to cleaning, and then by burning the object to be burnt in a mounted state on the plate. SOLUTION: The method comprises: (1) subjecting a waste plate 4 pressure- formed with materials for a ceramic resonator to cleaning at ca. 900 deg.C for 5 h.; (2) scattering zirconia powder, having ca. 50 μm average particle diameter, as a reaction-preventing powder 3 so as to be about 3 mm thick on the inside bottom of a burning sheath 2; (3) placing the waste plate 4 on the powder layer and then scattering zirconia powder as a reaction-preventing powder 3 so as to be about 15 mm thick; (4) putting a ceramic resonator element as an object 1 to be burnt on them and subjecting it to cleaning at ca. 900 deg.C for 5 h., followed by sintering it in a retained state at ca. 1,350 deg.C for 5 h. Thus, an excellent sintered compact free from uneven burnt portion in its exterior too is produced without deformation and a crack.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for firing ceramic electronic components for homogeneously sintering large ceramics such as base station filters among ceramic electronic components.

[0002]

2. Description of the Related Art In recent years, cavity resonator filters using ceramics have been actively used as filters for base stations from the viewpoint of performance. Among them, in a frequency band of several hundred MHz, the material characteristics of large-sized elements have been increasing. Demand is increasing.

As shown in FIG. 3, a powder 3 of the same material as that of the compact of the object 1 is sprayed on a firing sheath 2 as a material for preventing the reaction with the object 1, as shown in FIG. In general, a method of placing a molded body of the object to be fired 1 and firing it is performed. In particular, when the object to be fired 1 is a large ceramic, in order to completely perform the de-buying, it is necessary to perform the de-buying over a very long time, Alternatively, the firing was performed for a long time with a gentle firing curve.

[0004]

These large ceramic elements used for base stations have high Q values (Q = 1 / tan).
δ) is required, which requires a homogeneous and high-density ceramic. In the case of a large-sized ceramic element, in particular, when it is difficult to completely remove the binder in the firing step, and when the removal is incomplete, the density of the obtained ceramic is reduced, and a crack is generated in the sintered body.

[0005] However, in the case of a large-sized and heavy ceramic, the absolute amount of the binder contained in the molded body of the fired body 1 is large, and the firing shrinkage is also large. Accordingly, in the firing step, the binder is completely drawn out of the object 1 to be burned out of the system, and is decomposed and burned.
Has been a major challenge to shrink uniformly.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for firing large-sized ceramics, which comprises forming a material of the same material as the material to be fired on a discarded plate, removing alumina, beryllia, and magnesia. Or, spray one of zirconia as a reaction-preventing powder, and place the object to be fired on it and fire it, or replace it with a discarded plate of the same material and use any of alumina, beryllia, magnesia or zirconia porous By firing using a ceramic base plate, de-buying can be easily performed in a relatively short time, and uniform shrinkage can be achieved to achieve an intended purpose.

[0007]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, when firing a large-sized ceramic, a material of the same material as that of the ceramic is formed, and alumina, beryllia, magnesia, Alternatively, a ceramic electronic component is fired by spraying either zirconia as a reaction-preventing powder, placing a large ceramic compact thereon, and firing the ceramic electronic component. Since the plate has the same firing shrinkage behavior, it does not give shrinkage distortion in the sintering of the object to be fired, and does not affect the debuying of the object to be fired because the discarded plate has been removed. In addition, since the reaction preventing powder has a high melting temperature and a low activity for reacting with the material to be fired, the material to be fired is homogenized by the action of rollers during shrinkage during the sintering process without fusing with the material to be fired. Shrink And it has a use.

According to a second aspect of the present invention, when firing a large-sized ceramic, any one of alumina, beryllia, magnesia and zirconia is sprayed as a reaction-preventing powder on a porous ceramic base plate. A ceramic electronic component firing method in which a large ceramic molded body is placed on top and fired. By using a porous ceramic base plate, the gas removed in the firing process passes through the porous ceramic base plate from the bottom surface of the fired body As a result, the reaction preventive material has a function of uniformly shrinking the object to be fired by the action of the roller as described above, since the reaction preventing material is a powder and does not hinder the de-buying.

According to a third aspect of the present invention, there is provided the method for firing a ceramic electronic component according to the second aspect, wherein any one of alumina, beryllia, magnesia and zirconia is used as the material of the porous ceramic base plate. This defines the material of the base plate that does not adversely affect the sintering of the object to be fired.

According to a fourth aspect of the present invention, there is provided the method for firing a ceramic electronic component according to the third aspect, wherein a porous ceramic base plate having a porosity of 60 to 75% is used. It has sufficient mechanical strength against the load of the object, and can smoothly move the degassing gas from the bottom surface of the object to be fired.

Hereinafter, an embodiment of the present invention will be described using a hollow ceramic resonator for a base station (hereinafter referred to as a ceramic resonator) as a ceramic electronic component.

(Embodiment 1) FIG. 1 shows a state in which an object to be fired 1 according to the present invention is packed with a sinter 2.

First, a specified amount of a ceramic resonator material was weighed using zirconia (ZRO ₂ ), titanium oxide (TiO ₂ ), magnesium oxide (MgO), niobium oxide (Nb ₂ O ₅ ) and a small amount of additives. , According to known ceramic techniques.

First, using the obtained material, 250φ × 15
After forming a disc 4 mm with a pressure of 1 ton / cm ² , 90
Debuying was performed at a temperature of 0 ° C. for 5 hours.

Next, as a ceramic resonance element, a doughnut-shaped 240 φ × 85 × 120 mm element is used for 1 ton.
The molding was performed at a pressure of / cm ² .

Next, as shown in FIG. 1, a reaction-preventing powder 3 having an average particle diameter of 50 was formed on the bottom of the calcined sheath 3 made of alumina.
μm of zirconia powder is sprinkled to a thickness of about 3 mm, the trash plate 4 is further sprinkled thereon, and the zirconia powder is sprinkled thereon as a reaction preventing powder 3 to a thickness of about 15 mm. Was mounted at a temperature of 900 ° C. for 5 hours, and then sintered at a temperature of 1350 ° C. for 5 hours. The sintering state of the obtained sintered body is shown in (Table 1). As a comparative example, the results of a sintered body prepared by the conventional firing method shown in FIG. 3 are also shown.

[0017]

[Table 1]

As shown in Table 1, in the conventional firing method, the density of the sintered body was low, and the obtained sintered body was deformed into an elliptical donut shape and cracks occurred.
It can be seen that according to the method of the present invention, a good sintered body having no firing unevenness can be obtained in appearance. However, when the amount of the zirconia powder of the reaction preventing material 3 between the material 1 to be fired and the discarded plate 4 was small, cracks occurred in some cases. Therefore, it is desirable to spray the reaction preventive material 3 with a thickness of about 15 mm.

In the present embodiment, zirconia powder having an average particle size of 50 μm is used, but is not particularly limited thereto. However, when powder having a size of 1 to 5 μm is used, the effect of the roller on the weight of the object 1 is small. At the same time, the zirconia powder solidifies intensely, and a pulverizing step is required when reused, which is not preferable. Also, it has been confirmed that alumina, beryllia, and magnesia have similar effects in place of zirconia powder. However, it is needless to say that these powder materials need to be used in consideration of the composition of the material 1 to be fired. Further, spraying a suitable amount of the reaction preventing material powder 3 under the waste plate 4 includes the waste plate 4,
It can be said that this is an effective method capable of reducing friction with the bottom surface of the firing sheath 2 and performing uniform shrinkage.

(Embodiment 2) FIG. 2 shows a state in which a fired sheath 3 is packed by using a porous ceramic base plate 5 instead of the sacrificial plate 4 of Embodiment 1.

A porous ceramic base plate 5 made of zirconia having a porosity shown in (Table 2) was used instead of the discard plate 4.
The sintering was performed under the same conditions as the sheath filling conditions and the sintering conditions, and the results were shown in (Table 2).

[0022]

[Table 2]

As shown in (Table 2), 6 of the scope of the present invention
In the case of the porous ceramic base plate 5 having a porosity of 0 to 75%, no cracks or deformation due to uneven sintering were observed, but when the porosity was 50%, the material 1 to be fired passed through the porous ceramic base plate 5.
Cracks, which are considered to be due to insufficient de-buying from the steel, were observed, and the sintered density was low. On the other hand, porosity of 85
In the case of%, the porous ceramic base plate 5 could not withstand the load of the material 1 to be fired, causing warpage, and deformation of the sintered body due to this was observed.

In place of the zirconia powder, alumina,
It has been confirmed that the same effect can be obtained with the porous ceramic base plate 5 made of beryllia and magnesia.

[0025]

As described above, according to the present invention, when firing a large-sized ceramic molded body, the powder for the reaction preventing material is compared with the debris-removed discarded or porous ceramic base plate of the same material as the object to be fired. It is easy to remove the de-built by sintering the target and placing the object to be baked on it and firing it, and the obtained sintered body is free from cracks and uneven firing due to carbides of the binder residue, and is homogeneous Good quality shrunk ceramic can be obtained. In particular, it can be seen that this is an optimal firing method for ceramics that require homogeneity, such as large ceramic resonators for base stations.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a sheath filling method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a sheath filling method according to the second embodiment.

FIG. 3 is a sectional view showing a conventional sheath filling method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 object to be fired 2 fired sheath 3 reaction preventing powder 4 discarded plate 5 porous ceramic base plate

Claims (4)

[Claims] At the time of firing a large-sized ceramic, any one of alumina, beryllia, magnesia or zirconia is sprayed as a reaction-preventing powder on a discarded plate formed of the same material as that of the ceramic and de-built, A method for firing a ceramic electronic component in which a large ceramic compact is placed thereon and fired. 2. When firing a large ceramic, alumina, beryllia, magnesia or zirconia is sprayed as a reaction-preventing powder on a porous ceramic base plate, and a large ceramic molded body is placed thereon and fired. Firing method for ceramic electronic components. 3. The firing method for a ceramic electronic component according to claim 2, wherein any one of alumina, beryllia, magnesia, and zirconia is used as a material of the porous ceramic base plate. 4. The method for firing a ceramic electronic component according to claim 3, wherein a porous ceramic base plate having a porosity of 60 to 75% is used.