JPH05270925A - Refractory material for ceramic burning - Google Patents

Abstract

PURPOSE:To obtain the subject refractory material made inert to materials to be burnt, by providing the surface of a base material with a coating layer consisting of a specific stabilized zirconia. CONSTITUTION:Firstly, a base material with T-point average roughness of 15-100mum is prepared by burning a form produced by press molding or cast molding of a ceramic stock such as alumina powder, mullite powder, or cordierite powder. Thence, the surface of this base material is coated with a paste of stabilized zirconia 5-100mum in mean particle diameter to provide a coating layer 40-200mum thick, thus obtaining the objective refractory material with the base material firmly provided with the coating layer consisting of zirconia hard to react with functional parts such as ferrite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory material for firing ceramics used as a material for a kiln tool such as a jig for firing.

[0002]

2. Description of the Related Art Recently, functional materials such as sensors, capacitors, IC substrates, etc. are being replaced with ceramic materials. In particular, a dielectric element made of barium titanate or the like,
Magnetic materials made of composite oxides such as ferrite are widely used. Such a ceramic functional component is manufactured by mixing raw materials, molding them, placing the molded body on a firing jig, degreasing and firing it. Refractory materials such as mullite, alumina and cordierite are generally used as the material for the firing jig.

[0003]

However, in the above-described conventional firing jig using the refractory for firing ceramics as a base material, when the material to be fired is placed in contact with the surface of the base material and fired, In some cases, a reaction may occur between the surface of the material and the material to be fired, making it impossible to perform a good firing operation. This problem was particularly noticeable when firing functional parts such as ferrite, which needed to be fired at a high temperature.

[0004] In order to solve this problem
Japanese Patent No. 18499 discloses a baking mortar in which a zirconia powder layer and a co-dough powder layer are formed on the surface of a substrate and baked to form a thin film setter layer. However, the technique disclosed in Japanese Utility Model Laid-Open No. Sho 60-118499 described above only discloses forming a thin film setter from zirconia and eliminating the use of a conventional setter. There is no disclosure about the state of zirconia and the state of the base material, and there is a problem that the thin film setter peels from the surface of the base material depending on the conditions, and the intended function of the thin film setter cannot be fulfilled.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a refractory material for firing ceramics having a surface layer that does not react with the material to be fired.

[0006]

The refractory material for firing ceramics according to the present invention is a refractory material for firing ceramics used as a material for a firing jig for firing a ceramic molded body. It is characterized by having a coating layer having a thickness of 40 to 200 μm made of stabilized zirconia having a particle size of 5 to 100 μm.

[0007]

In the above-mentioned constitution, by providing a coating layer having a predetermined thickness of stabilized zirconia having a predetermined average particle diameter on the surface of the base material, it is preferable that the surface roughness of the base material surface at that time is predetermined. By setting the range, it is possible to provide a coating layer made of stabilized zirconia with good adhesiveness on the substrate surface, and as a result, a coating layer made of zirconia that does not easily react with functional components such as ferrite is firmly attached to the substrate surface. It is possible to obtain the refractory material for firing ceramics provided in the above.

Here, the average particle size of zirconia is 5 to 10
If the particle size is smaller than 0 μm, cracks may be generated during the sintering work, and the reactive gas or reaction substance during use may move toward the base material, which is not preferable as a firing refractory material. At the same time, if the particle size is larger than this, the denseness of the coating layer is lost, and the reaction resistance is not good like cracks. In addition, the thickness of the coating layer is 40
The reason for setting the thickness to ˜200 μm is that if it is thinner than this, it becomes impossible to block the reactive gas and the reaction substance, and if it is thicker than this, cracking occurs during sintering and the reaction resistance is not good.

[0009]

EXAMPLES In order to manufacture the refractory material for firing ceramics of the present invention, first, a ceramic raw material such as alumina powder, mullite powder, cordierite powder, etc. is obtained by press molding, cast molding, etc., and fired. The base material is manufactured by a general manufacturing method such as. As the base material, a porous refractory material which is advantageous in terms of thermal energy, which has been drawing attention in recent years, can be used. As an example, for example, Japanese Patent Publication 3-1
No. 9194 discloses a method of sintering heat-resistant inorganic fibers and refractory powder, and Japanese Laid-Open Patent Publication No. 3-1090 produces granules composed of hot-melt resin beads and high-purity alumina powder. Japanese Patent Publication No. 61-54752 discloses a method of dry press-molding the granules, and a method of obtaining a polyurethane foam mixed with a ceramic raw material and firing the same.

Next, the substrate is coated with a stabilized zirconia powder. For coating, first prepare a paste or the like made of stabilized zirconia having an average particle size of 5 to 100 μm, and from this paste, a thickness of 40 to 200
It is necessary to provide a μm zirconia layer. The coating method may be any conventionally known method such as an air spray method or a dipping method. Here, the surface roughness of the base material coated with zirconia is important in terms of reaction resistance and as a product.
That is, the surface roughness of the substrate is 15 to 1 in terms of ten-point average roughness.
00 μm is preferable, and when it is smoother, the adhesion of the coating layer after applying the coating material is poor,
It may peel off after several heat cycles. Also,
If it is rougher than that, the thickness of the coating layer becomes non-uniform, and the variation in the electrical characteristics of the fired ceramic may increase. It is considered that this is because the coating layer has a thin portion, which is affected by the base material and deteriorates the electrical characteristics of the ceramic. Therefore, it is desirable that the surface roughness of the base material is treated with fine ceramic powder to have a ten-point average roughness of 15 to 100 μm, and then the coating operation is performed.

An actual example will be described below. Example 1 40 parts by weight of water was added to 50 parts by weight of easily sinterable alumina having an average particle size of 0.6 μm and 50 parts by weight of synthetic mullite, and ball mill mixing was performed in a slurry form. To the slurry, add 15 parts by weight of hydrophilic urethane polymer and mix with a strong stirrer to obtain 200 x 200 x 1
It was poured into a 0 mm mold and foam-cured. Since the reaction is completed in a short time, it is necessary to pour it into the mold quickly. Next, the foamed and cured product is
Dried for 30 hours at 40 ° C., then 40 at 200-400 ° C.
After degreasing for a period of time, baking was performed at 1500 to 1650 ° C. to obtain a base material. The surface roughness of the obtained substrate was 50 μm in terms of ten-point average roughness. The ten-point average roughness is JIS B
0601. As a coating material,
Using Y ₂ O ₃ stabilized zirconia, the particle size shown in Table 1 below was compounded and adjusted, and the coating thickness was 120 μm to obtain a refractory material.

With respect to the obtained refractory material, the reactivity with barium titanate and the peelability of the coating layer were investigated and compared. Here, as for the reactivity, 200 g of barium titanate was placed on the zirconia coating layer of the above refractory material,
Firing was performed 20 times at 0 ° C. for 1 hour to confirm the reactivity between the coating layer and barium titanate and to evaluate the electrical characteristics of barium titanate. As a result, the good ones were marked with ◯, the good ones were marked with Δ, and the bad ones were marked with x. In addition, the peelability is 30% when the above refractory material is exposed to the atmosphere from an electric furnace at 1000 ° C.
The number of times the coating layer was peeled off and the coating layer was peeled off was shown.
The results are shown in Table 1. From the results of Table 1, it can be seen that the examples of the present invention in which the particle diameter of the coating layer is 5 to 100 μm can obtain better results than the other comparative examples.

[0013]

[Table 1]

Example 2 A base material was produced by the same method as in Example 1, and CaO-stabilized zirconia having a particle size of 5 to 75 μm was used on the surface of the obtained base material, and the results are shown in Table 2 below. A refractory material was obtained by coating in various thicknesses, and the obtained refractory material was used in Example 1
Similar reactivity and peelability were measured and compared. The results are shown in Table 2. From the results shown in Table 2, it can be seen that the examples of the present invention in which the thickness of the coating layer is 40 to 200 μm can provide better results than the other comparative examples.

[0015]

[Table 2]

Example 3 To 70 parts by weight of easily sinterable alumina having an average particle size of 0.6 μm,
30 parts by weight of synthetic mullite, 2.0 parts by weight of molding binder, and 20 parts by weight of styrene beads having a particle size of 200 μm or less were dry-mixed with a ball mill to obtain a raw material. The obtained raw material is dry-pressed to 200 × 200 × 1
A molded product having a shape of 0 mm was obtained. The obtained molded body is
Sintering was performed at a temperature of 00 to 1600 ° C. to prepare base materials having various surface roughness as shown in Table 3 below. Next, the surface of the prepared substrate is coated with fused alumina having an average particle size of 1.5 μm (or fused mullite having a particle size of 1.0 μm) to the surface roughness shown in Table 3 below. A 120 μm coating of Y ₂ O ₃ -stabilized zirconia having a particle size of 5 to 75 μm was applied onto the treated and untreated ones to obtain a refractory material. Similar to Example 1, the obtained refractory material was compared for obtaining reactivity and peeling property. The results are shown in Table 3. From the results of Table 3, it can be seen that good results can be obtained when the surface roughness is 15 to 100 μm.

[0017]

[Table 3]

[0018]

As is apparent from the above description, according to the present invention, a coating layer having a predetermined thickness of stabilized zirconia having a predetermined average particle size is provided on the surface of a substrate, and preferably in that case. Since the surface roughness of the base material is within the specified range, a coating layer consisting of stabilized zirconia with good adhesiveness can be provided on the base material surface, and as a result, zirconia that does not easily react with functional parts such as ferrite. It is possible to obtain a refractory material for firing ceramics in which a coating layer made of is firmly provided on the surface of the base material.

Claims (2)

[Claims] 1. A refractory material for firing ceramics, which is used as a material for a firing jig or the like for firing a ceramic molded body, comprising 40 to 200 μm of stabilized zirconia having an average particle diameter of 5 to 100 μm on the surface of a base material. A refractory material for firing ceramics, which has a coating layer having a thickness of. 2. The refractory material for firing ceramics according to claim 1, wherein the surface of the substrate on which the coating layer is provided has a ten-point average roughness of 15 to 100 μm.