TWI383965B - A ceramic material for a ceramic ceramic container, a method for manufacturing the same, and a method for producing the same - Google Patents

Description

Tool material for laminating ceramic capacitor firing, manufacturing method thereof and regeneration method

The present invention relates to a SiC tool material (SiC-based) such as a setter, a shelf, and a crucible used in a firing or heat treatment step of a multiple-layer ceramic capacitor (hereinafter referred to as MLCC). Material), its manufacturing method, and regeneration method.

The firing or heat treatment of ceramics for electronic parts is usually carried out at a temperature ranging from 1000 to 1400 °C. Therefore, as a tool material for firing, a mullite (Al ₂ O ₃ -SiO ₂ ) group, an Al ₂ O ₃ -SiO ₂ -MgO group, a MgO-Al ₂ O ₃ -ZrO ₂ group, and carbonization are used. A ceramic having excellent heat resistance such as a bismuth (SiC) group. Among these ceramics, SiC-based ceramics are particularly preferable as materials which are excellent in heat resistance and creep resistance.

However, for example, when MLCC having barium titanate (BaTiO ₃ ) as a main component is fired, for example, the MLCC as a burned material is directly placed on the tool material for firing of the SiC ceramic. When the MLCC is in contact with the tool material for firing, when the temperature is 1100 ° C or higher, the MLCC reacts with the SiC of the tool material, and the MLCC is liable to cause sintering abnormality or fusion such as discoloration.

On the other hand, in the firing of MLCC, it is necessary to fire the oxide BaTiO ₃ as a main component without oxidizing the electrode material. Therefore, the partial pressure of oxygen in the furnace environment is an important factor. However, in the case of using a tool material for firing of SiC ceramics, the oxygen partial pressure in the furnace may fluctuate due to the oxidation reaction of SiC.

Therefore, in the case of firing of MLCC, a tool material which is formed of a ceramic such as ZrO ₂ excellent in reactivity resistance to form a surface is used, and specifically, a ceramic is covered with a ceramic such as Al ₂ O ₃ or ZrO ₂ . The surface of the substrate.

Such a coated material is formed by a method of applying a ceramic slurry required for coating a ceramic substrate to a high temperature, a method of sintering at a high temperature, a CVD (Chemical Vapor Deposition) method, a sputtering method, or the like. Come to get. Among these methods, the spray method is particularly useful because a film that is difficult to peel off can be obtained.

Specifically, for example, in Patent Documents 1 and 2, it is disclosed that Al ₂ O ₃ , Al ₂ O ₃ -SiC, and ZrO ₂ are sprayed on the surface of a SiC-based ceramic substrate excellent in heat resistance and creep resistance. A tool material for firing (such as a heat treatment jig).

Further, Patent Document 3 discloses a material for firing a SiC substrate having a high porosity in which an SiO ₂ layer is formed by using ZrO ₂ or Al ₂ O ₃ .

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-278685

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-306392

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2006-117472

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2002-145671

However, the SiC-based ceramic substrate of the tool material for firing described in Patent Document 1 is a dense body having a low porosity, and the surface of the dense film must be roughened in order to make the spray film adhere to each other. It costs a lot.

On the other hand, in the case of firing of the MLCC, in order to reduce the cost, it is necessary to increase the production efficiency by effectively using the furnace space and rapidly increasing the temperature. For this reason, the tool material for firing is required to have a reduced thickness and a low heat capacity. However, the tool material for multilayer firing having the configuration described in Patent Document 2 described above has a limited degree of thinning.

In addition, the wafer-shaped MLCC containing BaTiO ₃ as a main component is significantly reduced in size in recent years, and is easily affected by fluctuations in the furnace environment during firing, and is even the material for firing described in Patent Document 3 Also, it is not possible to sufficiently prevent the sintering abnormality such as discoloration caused by the oxidation reaction or the like of the SiC substrate as described above. In particular, it cannot be asserted that it is suitable for repeated use.

Further, in the tool material of Patent Document 1, the substrate itself rarely ruptures or warps during use, but it may not be reused due to peeling of the film or reaction with the finished product. The substrate of the tool material that cannot be reused can be reused by itself, and thus the waste is less preferable from the viewpoint of reducing the firing cost of the tool material and reducing the waste.

Therefore, it is preferable to reuse the tool material as in the invention described in Patent Document 4.

The method for regenerating the tool material described in Patent Document 4 is based on a surface of a dense SiC substrate having a SiC of 97% and an apparent porosity of 0%, and is formed of Al ₂ O ₃ or Al ₂ O ₃ - a method for regenerating a tool material of at least one of SiO ₂ , ZrO ₂ , and MgAl ₂ O ₃ (spinel) or a plurality of ceramic coatings having a main component, the regeneration method being performed after using the tool material several times The surface of the dense SiC substrate is sprayed with a ceramic film of 30 to 500 μm to be regenerated.

Such a regeneration method is suitable for regeneration of a tool material using a dense SiC substrate, but is not suitable for regeneration of a tool material using a porous SiC substrate. Further, in order to remove the film and regenerate, the surface roughness of the surface of the SiC substrate after the film removal is required to be about 3 to 15 μm. However, depending on the application, the convex portion of the surface of the SiC may be oxidized or When the components of the burned material react, the strength is lowered, and if the film is removed, sufficient surface roughness cannot be obtained.

Since the hardness of SiC is extremely high, it is difficult to cope with the roughening treatment by a mechanical roughening method such as spraying. Although the roughening treatment can be performed again by chemical etching or the like, the substrate after use has a phenomenon in which the surface strength is lowered and the components to be fired are infiltrated, and the degree of roughening varies depending on the course of use of the product. It is difficult to obtain a stable rough surface under a fixed condition, and it is necessary to adjust the etching conditions according to the use condition of the substrate, so that the cost is increased.

The present invention has been made to solve the above-mentioned technical problems, and an object of the invention is to provide a tool material for MLCC firing, a method for producing the same, and a method for regenerating the same, which can improve energy saving and production efficiency during firing, and is also suitable for repetition. Use, so you can reduce costs.

According to a first aspect of the present invention, there is provided a SiC substrate and an SiO ₂ layer formed on a surface of the SiC substrate, and the laminated ceramic capacitor firing tool material is provided. The apparent porosity is 15% or more, the specific gravity is 3.05 to 3.20, the SiC content is 90% by weight or more, and the surface of the SiO ₂ layer is formed on at least a portion of the multilayer ceramic capacitor as the fired material. A coating layer of at least one of ZrO ₂ or Al ₂ O ₃ . By using the tool material having the above-described configuration, oxidation of the substrate SiC can be suppressed, and fluctuations in oxygen concentration accompanying the oxidation reaction are small, and sintering such as discoloration of the MLCC as a burned material can be prevented. abnormal.

According to a second aspect of the present invention, there is provided a SiC substrate and an SiO ₂ layer formed on a surface of the SiC substrate, and the laminated ceramic capacitor is fired. The tool material has a apparent porosity of 15% or more, an apparent specific gravity of 3.05 to 3.20, a SiC content of 90% by weight or more, and a surface of the SiO ₂ layer on which at least a portion of the multilayer ceramic capacitor as the fired material is placed. a coating layer comprising at least one of ZrO ₂ or Al ₂ O ₃ formed by a sputtering method, and comprising Al ₂ O ₃ or Al ₂ between the SiO ₂ layer and the coating layer An intermediate layer of at least one of O ₃ -SiO ₂ . By the intermediate layer, the difference in thermal expansion between the SiC substrate having the SiO ₂ layer and the coating layer can be reduced, and the peeling resistance of the coating layer can be improved, and the adhesion of the coating layer can be improved by the spray film. .

According to a third aspect of the present invention, there is provided a SiC base material and an SiO ₂ layer formed on a surface of the SiC base material, wherein the laminated ceramic capacitor is fired. The tool material has a apparent porosity of 15% or more, an apparent specific gravity of 3.05 to 3.20, a SiC content of 90% by weight or more, and the SiO ₂ layer is formed by oxidation of the surface of the SiC substrate, and is disposed at least. A coating layer containing at least one of ZrO ₂ or Al ₂ O ₃ is formed on the surface of the SiO ₂ layer as a part of the multilayer ceramic capacitor of the fired material. A strong SiO ₂ layer can be easily formed by an oxidation treatment.

According to the fourth aspect of the present invention, there is provided a multilayer ceramic capacitor above the tool material for firing, in which the total content of SiO SiC SiC substrate of the above-mentioned SiO ₂ layer _2, the SiO ₂ layer of SiO with respect to the above-described The content of ₂ is 1 to 4% by weight. When the amount of SiO ₂ is in the above range, the SiO ₂ layer can be sufficiently formed on the SiC crystal surface of the SiC substrate, and the heat resistance can be maintained.

According to a fifth aspect of the present invention, there is provided a method of producing a tool material for firing a multilayer ceramic capacitor, comprising the steps of: adding an organic carbon in a SiC powder raw material to a residual carbon ratio of less than 5.0% by weight after sintering a step of mixing and mixing the powder to obtain a mixed powder; adding water to the mixture and kneading to form a porous formed body; and sintering the porous formed body at a temperature of 1500 ° C or higher and 2400 ° C or lower The step of obtaining a sintered body; firing the sintered body at a temperature of 1350 ° C or higher and 1650 ° C or lower for 1 hour or longer and 6 hours or less in an oxygen atmosphere having an oxygen concentration of 2% or more, and forming the sintered body on the surface of the sintered body a step of forming a SiO ₂ layer; and forming a coating layer containing at least one of ZrO ₂ or Al ₂ O ₃ by a sputtering method on the surface of the SiO ₂ layer.

According to such a production method, the above-described MLCC baking tool material of the present invention can be preferably obtained.

According to a sixth aspect of the present invention, there is provided a method of regenerating a tool material for firing a multilayer ceramic capacitor according to the first aspect of the invention, wherein the laminated ceramic capacitor The method for regenerating the tool material for firing is a step of removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate after the polishing tool material is used several times; re is formed on the surface of the sheet of the step of SiO ₂ layers; and on the upper surface of the SiO ₂ layer of the re-formed, the re-formed in a thickness of less than 30 μm, 500 μm or less them with _{Al 2 O 3, ZrO 2,} Al 2 O 3 a step of at least one of SiO ₂ and ZrSiO ₄ or a plurality of coating layers as a main component.

According to a seventh aspect of the present invention, there is provided a method of regenerating a tool material for firing a multilayer ceramic capacitor according to the first aspect of the invention, wherein the laminated ceramic capacitor The method for regenerating the tool material for firing is to remove the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate after the polishing tool material is used several times; in an oxidizing environment at a temperature of 1350 deg.] C for more than 2 hours of a heat treatment, whereby the surface of the SiC substrate in the step of re-forming of the SiO ₂ layer; and to the upper surface of the SiO ₂ layer of the re-formed, re-formed in a thickness of 30 μm The step of using at least one of a plurality of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ or a plurality of coating layers as a main component of 500 μm or less.

According to an eighth aspect of the present invention, there is provided a method of regenerating a tool material for firing a multilayer ceramic capacitor according to the first aspect of the invention, wherein the laminated ceramic capacitor The method of regenerating the tool material for firing is performed by using the material for the above-mentioned baking tool several times, and performing the following steps: removing the SiO ₂ layer formed on the surface of the SiC substrate by bead blasting or planar polishing And the step of coating the layer; performing a heat treatment at a temperature of 1350 ° C or higher for 2 hours or more in an oxidizing atmosphere, thereby re-forming the SiO ₂ layer on the surface of the SiC substrate; and reforming the SiO _On the surface of the _two layers, a coating having a thickness of 30 μm or more and 500 μm or less and having at least one or a plurality of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ as a main component is further formed. The steps of the layer.

According to a ninth aspect of the present invention, there is provided a method for regenerating a tool material for laminating a ceramic capacitor according to the seventh to twelfth aspects of the present invention, wherein in the step of reforming the coating layer, a plasma spray or a gas gel is used. Any one or a combination of deposition, vapor deposition or CVD (Chemical Vapor Deposition).

According to a tenth aspect of the present invention, in the method for regenerating a tool material for laminating a ceramic capacitor according to the seventh to twelfth aspects of the present invention, in the step of reforming the coating layer, the slurry is applied and then heated to 1400. Burning is carried out above °C.

As described above, when the tool material for MLCC baking of the present invention is used, energy saving and production efficiency at the time of firing can be improved, and the sintering abnormality such as discoloration of MLCC can be prevented from being used, so that it can be reduced. cost.

Therefore, the above MLCC firing tool material can contribute to efficient and inexpensive manufacture of MLCC.

Further, according to the production method of the present invention, the MLCC baking tool material can be preferably produced.

According to the method of regenerating the tool material of the present invention, it is possible to provide a A method of regenerating a tool material using a porous SiC substrate and using a tool material which is inexpensive.

Hereinafter, the present invention will be described in more detail.

The present invention MLCC firing tool material, formed on the surface of the SiC base material with a SiO ₂ layer, and further, at least on the surface of the SiO as the mounting portion of the ceramic capacitor to be fired laminate of _two layers, there is formed comprising ZrO ₂ or a coating layer of at least one of Al ₂ O ₃ .

That is, the present invention is a tool material for firing using SiC as a substrate, and is configured as follows: an SiO ₂ layer is formed on the surface of the SiC substrate in advance, and a main component of the MLCC is formed on the SiO ₂ layer. That is, a surface layer formed of ZrO ₂ or Al ₂ O ₃ which is a material having excellent resistance to reactivity of BaTiO ₃ .

According to the blasting tool material of the present invention, the SiO ₂ layer formed on the surface of the SiC substrate can suppress the oxidation of SiC of the substrate, and the fluctuation of the oxygen concentration accompanying the oxidation reaction can be reduced. Sintering abnormalities such as discoloration of MLCC as a burned material are prevented.

Further, as described above, by suppressing oxidation of the substrate SiC, physical properties at the interface between the SiC substrate and the coating layer can be prevented from being changed, and an effect of suppressing cracking or peeling of the coating layer can be obtained.

The SiO ₂ layer which functions as described above is preferably formed by oxidation of the surface of the SiC substrate.

By the oxidation treatment, a SiO ₂ layer having a uniform thickness can be easily and firmly formed on the entire surface of the substrate.

SiC substrate with respect to the total amount of SiC and SiO ₂ of the layer ₂ SiO, SiO ₂ layer is preferably in the above-described SiO ₂ content of 1 to 4 wt%.

When the SiO _{2 is} less than 1% by weight, the SiO ₂ layer may not be sufficiently formed on the SiC crystal surface of the SiC substrate.

On the other hand, when the amount of the SiO ₂ exceeds 4% by weight, the heat resistance is lowered, and the SiO ₂ layer becomes too thick, whereby the difference in thermal expansion coefficient between the SiO ₂ layer and the coating layer becomes remarkable, and the coating layer is The adhesion is also reduced, so it is not good.

Moreover, it is preferable that the baking tool material has a apparent porosity of 15% or more, an apparent specific gravity of 3.05 to 3.20, and an SiC content of 90% by weight or more.

When the porosity, the specific gravity, and the SiC content are in the above range, it is possible to realize a tool material which is lightweight and has sufficient heat resistance while maintaining the adhesion of the coating layer. Thereby, the handling of the tool material at the time of firing is also facilitated, and the production efficiency of the MLCC can be improved.

Moreover, the apparent porosity of the above-mentioned baking tool material is preferably 60% or less. The reason for this is that when the porosity is more than 60%, the surface area is increased and the influence of oxidation is increased. As a result, when the present invention is applied as a tool for baking a thin wall, the strength may be insufficient.

Further, the baking tool material may form an intermediate layer containing at least one of Al ₂ O ₃ or Al ₂ O ₃ -SiC between the SiO ₂ layer and the coating layer, and on the intermediate layer The coating layer containing at least one of ZrO ₂ or Al ₂ O ₃ is formed as a molten film.

The intermediate layer functions to reduce the difference in thermal expansion between the SiC substrate having the SiO ₂ layer and the coating layer, and can improve the peeling resistance of the coating layer, and further suppress the contact of the MLCC with the tool material during firing. Partial reaction.

Thereby, the number of times the tool material can be reused can also be increased.

The tool material for MLCC firing as described above can be preferably obtained by the production method of the present invention. The outline of the manufacturing steps will be described below.

First, an organic binder having a residual carbon ratio of less than 5.0% by weight after sintering is added to the SiC powder raw material and mixed to obtain a mixture.

As the SiC powder raw material, SiC powder which is generally used in the production of such SiC-based ceramics can be used. For example, a commercially available product having a purity of about 90% or more and an average particle diameter of about 0.1 to 200 μm can be used. However, from the viewpoint of preventing reaction with the burned material, the purity is preferably 95% or more. The high purity SiC powder preferably has a purity of 99% or more. Further, the powder particle size may be heterogeneous, and may be a mixed powder of a fine particle product (average particle diameter of 0.5 to 10 μm) and a coarse particle product (average particle diameter of 20 to 200 μm).

In addition, as the organic binder, a general user can be used, and specific examples thereof include an aromatic resin binder such as a phenol formaldehyde resin, a phenol formaldehyde resin, a polybenzimidazole resin, and a polyphenylene; An aliphatic resin binder such as vinyl chloride, polyvinylidene chloride or a polyacrylic resin; and various organic binders such as a silicone resin, methyl cellulose, carboxymethyl cellulose, and tar pitch.

The amount of the organic binder added is such that the residual carbon ratio after sintering is less than 5.0% by weight.

When the residual carbon ratio exceeds 5.0% by weight, the amount of oxidation increases, and the oxidation treatment time becomes long.

Next, water is added to the mixture of the SiC powder raw material and the organic binder obtained in the above manner, and then kneaded to form a porous molded body.

As the molding method, a usual method such as press, rubber press, extrusion, and slip casting can be used, and formed into a desired shape by these methods.

Further, the porous formed body obtained by the above-described method is sintered at a temperature of 1,500 to 2,400 ° C, and then heated in an oxygen atmosphere to carry out an oxidation treatment to form an SiO ₂ layer on the surface of the sintered body.

In the above oxidation treatment, the oxygen concentration in the furnace environment is preferably 2% or more.

If the oxygen concentration is less than 2%, the time required to form a sufficient SiO ₂ layer on the surface of the SiC substrate becomes long, which is not preferable.

Further, the firing temperature at the time of the oxidation treatment is preferably from 1,350 to 1,650 °C.

If the above firing temperature is less than 1350 ° C, the time required to form the desired SiO ₂ layer will become long, which is not preferable.

On the other hand, when the baking temperature exceeds 1650 ° C, the oxidation reaction of SiC becomes intense, and the SiO ₂ layer is foamed or cracked by softening, so that a stable film cannot be formed.

Then, a coating layer containing at least one of ZrO ₂ or Al ₂ O ₃ is formed on the surface of the SiO ₂ layer.

As a method of forming the coating layer, a method of spraying, a ceramic slurry required for coating, a method of baking at a high temperature, a CVD (Chemical Vapor Deposition) method, or the like can be used. However, in the present invention, Real The physical adhesion of the anchor effect is now used to make the formed coating layer difficult to peel off from the substrate, and it is preferable to form it by a spray method such as plasma spraying.

The spray method also has the advantage of being able to obtain a coating layer which is dense, has a small specific surface area, and is excellent in reactivity with a burned material.

Particularly, a coating layer formed by a water plasma spray method is preferred because the surface roughness is large, the contact area with the object to be fired is small, and it is difficult to react with the object to be fired.

The coating layer may be formed on the entire surface of the SiO ₂ layer as needed, or may be formed only on a part of the substrate including the portion of the MLCC on which the object to be fired is placed.

The material of the coating layer is preferably ZrO ₂ or Al ₂ O ₃ because it is required to have reactivity with MLCC as a burned material, such as durability against peeling or peeling.

Further, in the case where the coating layer is formed by a molten film of ZrO ₂ , it is preferred to stabilize the unstabilized zirconia, calcium oxide (CaO) or yttrium oxide (Y ₂ O ₃ ). The stabilized zirconia or partially stabilized zirconia of the agent is mixed together. From the viewpoint of preventing the peeling of the coating layer, the mixing ratio is preferably 30 to 60% by weight of the stabilized or partially stabilized zirconia, and 70 to 40% by weight of the unstabilized zirconia.

Further, after forming an intermediate layer containing at least one of Al ₂ O ₃ or Al ₂ O ₃ -SiO ₂ on the surface of the SiO ₂ layer, the coating layer may be formed on the intermediate layer.

The intermediate layer has a coefficient of thermal expansion between the substrate including the SiO ₂ layer and the coating layer, and the difference in thermal expansion between the _two layers can be reduced, so that the peeling of the coating layer can be effectively prevented.

As a method of forming the intermediate layer, a method in which a specific material such as Al ₂ O ₃ -SiC is formed into a slurry, coated by spraying or the like, and fired at a high temperature, and a plasma spray is used. A method of forming a film by a spray method or the like.

Among these methods, from the viewpoint of improving the adhesion of the film and preventing peeling, it is preferably formed by a spray method. In particular, the film formed by the water plasma spray method can suppress peeling by the effects of low modulus of elasticity, small thermal stress accompanying expansion and contraction, dispersion of stress, and relaxation of self-expansion.

[Examples]

Hereinafter, the present invention will be more specifically described based on the examples, but the present invention is not limited by the following examples.

[Example 1]

First, a methylcellulose-based binder having a residual carbon ratio after sintering of less than 5.0% by weight is added to the SiC powder raw material and mixed to obtain a mixture.

Water was added to the above mixture, followed by kneading, and press molding, whereby a porous formed body was obtained.

The porous formed body was sintered at a temperature of 2300 ° C, and then oxidized at a temperature of 1350 ° C for 3 hours in an oxygen atmosphere having an oxygen concentration of 4% to form an SiO ₂ layer on the surface of the sintered body. To produce a SiC substrate having a SiO ₂ layer (ceria layer) of 150 mm × 150 mm × 3 mm in thickness.

The apparent porosity and apparent specific gravity of the above substrate were measured in accordance with JIS (Japanese Industrial Standard) R2205-1992. Here, the apparent porosity and the apparent specific gravity are values calculated for the SiC substrate including the SiO ₂ layer.

Further, a test piece (about 1 g) of 10 mm × 10 mm × 3 mm in thickness was cut out from the substrate, and the sample piece was immersed in an aqueous hydrogen fluoride solution (1:1), and the weight was reduced according to 60 minutes later. The amount of SiO _{2 was} determined.

Further, on the surface of the substrate of 150 mm × 150 mm × 3 mm in thickness, an Al ₂ O ₃ film (intermediate layer) having a thickness of 150 μm is formed by spraying with a water plasma, and further formed on the film. A ZrO ₂ film (coating layer) having a thickness of 150 μm is used as a locator for MLCC firing.

Using this locator, the MLCC firing test was performed, and the firing state of MLCC such as firing abnormality (discoloration) was evaluated.

Further, in order to inspect the oxidation state of the positioner in the MLCC firing test, a SiC substrate test piece having a SiO ₂ layer of 10 mm × 10 mm × 3 mm thickness was placed in the firing furnace simultaneously with the above positioner. The amount of SiO ₂ after firing once and after firing 10 times was determined in the same manner as above.

[Comparative Example 1]

The measurement of the amount of SiO ₂ and the MLCC firing test were carried out in the same manner as in Example 1 except that the SiC substrate which was not oxidized was used.

[Examples 2 to 4, Comparative Example 2, Comparative Example 3]

The amount of SiO ₂ was measured in the same manner as in Example 1 except that the firing temperature in the oxidation treatment was changed to the temperatures shown in Examples 2 to 4, Comparative Example 2, and Comparative Example 3 of Table 1. And MLCC firing test.

The measurement and evaluation results of the above examples and comparative examples are shown together in Table 1.

Further, in the evaluation of the MLCC calcined state in Table 1, ◎ indicates good, ○ indicates that it was substantially good, and × indicates that firing abnormality occurred.

According to the results shown in Table 1, it is understood that in the case where the SiO ₂ layer is sufficiently formed by the oxidation treatment (Examples 1 to 4), in particular, in Example 3 and Example 4 in which the amount of SiO ₂ is larger, MLCC is burned. The progress of the further oxidation reaction of the formed SiC was suppressed, and the MLCC burned state was also good.

On the other hand, when the formation of the SiO ₂ layer by the oxidation treatment is not sufficient (Comparative Example 1 and Comparative Example 2), the amount of SiO ₂ in the MLCC firing is large, and the MLCC is fired. abnormal. The reason for this is that when the amount of SiO ₂ is increased in a large amount, the amount of change in the oxygen concentration in the firing furnace increases due to the oxidation reaction of the substrate SiC.

Further, when the oxidation treatment temperature was 1700 ° C (Comparative Example 3), the oxidation reaction became intense, and foaming was caused, and it was difficult to form a desired SiO ₂ layer. Since the SiO ₂ layer was partially formed, the apparent porosity, the apparent specific gravity, and the amount of SiO ₂ measured in this portion are shown in parentheses in Table 1.

Next, a method of reproducing the above-described tool material of the present invention will be described.

The object of the present invention is a tool material which comprises, as a substrate for mounting a ceramic component, that is, a material to be fired, having an apparent porosity of 15% or more and a bending strength of 35 MPa. more porous SiC base material, and the shape of the porous SiC substrate mass SiO ₂ layer, and in that the SiO ₂ layer at least on the firing of the upper surface portion thereof, formed with a Al ₂ O ₃ At least one of ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ or a plurality of ceramic films having a plurality of components as a main component.

In the regeneration method according to an embodiment of the present invention, after the tool material is used several times, the ceramic film formed on the surface of the SiO ₂ layer is removed, and Al ₂ O ₃ and ZrO ₂ having a thickness of 30 to 500 μm are newly formed. Regeneration is achieved by at least one of Al ₂ O ₃ -SiO ₂ and ZrSiO ₄ or a plurality of ceramic coatings containing a plurality of components.

In the above-mentioned laminated ceramic capacitor tool material, when the burned material is directly placed on the surface of SiC, a reaction often occurs. Therefore, it is necessary to form a surface coating resistant to reactivity such as Al ₂ O ₃ or ZrO ₂ . In order to form a surface film, it is necessary to roughen the surface (1) of the substrate to improve the adhesion to the substrate, and it is necessary to use (2) a porous substrate.

When the fired material is loaded at a high temperature and the above-mentioned laminated ceramic capacitor tool material is used, the substrate is deteriorated due to oxidation or reaction with the burned material component that has penetrated into the film. The degree of deterioration of the surface portion of the substrate which was first affected by foreign components was particularly large. Therefore, when the film is removed by reusing the substrate, the convex portion on the surface of the substrate also disappears together with the film, and the surface roughness for forming the film is not sufficiently obtained.

Therefore, for a dense SiC substrate, it is necessary to perform a roughening treatment such as chemical etching again.

On the other hand, in the porous base material which is the tool material of the present regeneration method, even if a part of the surface portion of the base material is broken due to embrittlement, since the base material originally has a structure of a plurality of pores, it can always be obtained. A surface with good adhesion to the film. Therefore, the present regeneration method does not require re-roughening treatment, and the tool material can be regenerated inexpensively as compared with the regeneration method in the case of using a dense SiC substrate which requires roughening treatment such as chemical etching.

When the surface of the substrate for loading a highly burned material is embrittled by a reaction, if it is a porous substrate, the embrittlement portion may be removed by mechanical processing such as polishing. use.

When considering the adhesion to the film, the apparent porosity of the substrate must be 15% or more. Fig. 1 and Fig. 2 show a cross-sectional structure in which a film is formed on a porous SiC substrate having a porosity of 27%. It is understood that it has an anchor structure in which the film is immersed in the pores of the substrate or the ruthenium dioxide layer.

If the apparent porosity of the substrate is less than 15%, a sufficient anchoring effect cannot be obtained between the film, the substrate, and the ceria layer, and peeling of the film occurs at the initial stage of use.

The greater the apparent porosity, the higher the adhesion of the film, but the lower the strength of the substrate.

As for the strength, the bending strength must be 35 MPa or more. If the bending strength is less than 35 MPa, depending on the shape of the tool material, for example, in the case of a thin-walled positioner having a thickness of 1 to 3 mm, cracking may occur.

As a method of making the substrate porous, the particle size structure of the raw material can be cited. A method of adjusting the method, adding a space forming material that disappears during firing, and forming a state in which bubbles are formed in the slurry. For the firing, any of conventional sintering and reaction sintering may be used. However, it is preferred to carry out sintering by recrystallization, which does not cause shrinkage due to sintering, and the porosity before sintering can be substantially maintained. In order to promote recrystallization, it is usually necessary to carry out sintering at a temperature of about 1,500 to 2,500 °C.

When a tool material is used in an oxygen-containing atmosphere at a high temperature (about 1300 ° C or higher), gas exchange with SiC oxidation may occur at the initial stage of use, which may adversely affect the burned material. Therefore, before the film is added to the surface of the substrate, the ruthenium dioxide layer is formed by oxidation in advance, and then a film is formed. By the effect of the ruthenium dioxide layer, the influence of the reaction accompanying the initial oxidation can be alleviated.

As the film of the outermost surface, ZrO ₂ or Al ₂ O ₃ which is difficult to react with a ceramic electronic component material such as barium titanate or ferrite is preferable. Particularly preferred is ZrO _{2 which} is difficult to react with most materials. ZrO _{2 has a} larger thermal expansion than the substrate SiC. Therefore, when used at a high temperature, a stress due to a difference in thermal expansion occurs between ZrO ₂ and the SiC substrate.

In order to reduce the stress, if an Al ₂ O ₃ , Al ₂ O ₃ —SiO ₂ , or ZrSiO ₄ film having a thermal expansion coefficient therebetween is formed between the ZrO ₂ film and the SiC substrate, it is difficult to produce Stripped.

Further, in the present invention, an intermediate layer such as Al ₂ O ₃ , Al ₂ O ₃ -SiO ₂ or ZrSiO _{4 is} provided between the SiC substrate and the ZrO ₂ film (the thickness of the SiO ₂ layer is small, so The SiO ₂ layer cannot be shown at the magnification of Fig. 2).

However, even if the SiO ₂ layer is interposed, the thermal expansion relaxation effect of the intermediate layer such as Al ₂ O ₃ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ does not decrease, so that the SiO ₂ layer does not adversely affect the thermal expansion relaxation effect.

The thickness of the film is preferably from 30 to 500 μm. The thickness of the film depends on the porosity of the film, the size of the particles, etc., but if the thickness is less than 30 μm, even a dense film may locally cause pores or cracks to be continuous, and SiO ₂ or burned material on the surface of the substrate. Since the component passes through the film in a short time, and the reaction between the burned material and SiO ₂ or the burned material and SiC is caused, it is not preferable.

When the film thickness of the film is increased, the time required for the SiO ₂ or the component to be fired to cross the film becomes longer, but if the film thickness is more than 1000 μm, the thermal expansion of the SiC substrate and the film is poor. The proportion of stress increases and it is easy to cause peeling.

In order to form a film, there are methods such as plasma spraying, slurry coating and baking, aero-sol deposition, gas deposition, and CVD (Chemical Vapor Deposition).

In particular, in the plasma spray in which the molten raw material collides with the substrate at a high speed and is instantaneously solidified, the film is caught in the pore portion of the SiC substrate, and a film having an anchoring structure effective for preventing peeling can be formed.

That is, when a ceramic electronic component such as barium titanate or ferrite is easily used and fired a plurality of times, and the knife film is peeled off, or the reaction component on the surface of the film is increased to cause a reaction with the loaded object, and the container cannot be used, When the SiC substrate itself is not broken or warped, the old film and the old SiO ₂ layer are removed, and the film and the SiO ₂ layer are reformed, and the substrate can be reused.

The removal of the film and the SiO ₂ layer can be carried out by a processing method such as shot blast or plane polishing. Since the porous substrate is a porous substrate, a surface having appropriate pores and a registration effect with the coating film and suitable for film formation can be obtained.

After the film and the ceria layer are removed, the film is formed in the same manner as the method of forming the film for the first time. By repeating the above operations, multiple reuses can be performed.

In addition, the method and conditions for measuring the porosity are based on JIS (Japanese Industrial Standard) R 2205 "Method for Measuring the Porosity of Refractory Bricks". The method and conditions for measuring the bending strength are based on JIS R 2213 "Method for Measuring the Flexural Strength of Refractory Bricks". Preferably, the plasma spray is a water plasma spray.

According to the method for regenerating the tool material of the present embodiment, it is possible to realize a method of regenerating a tool material suitable for regeneration using a tool material of a porous SiC substrate.

[Examples] (Example 5)

After forming a hafnium oxide layer on a recrystallized porous SiC substrate having a porosity of 27%, a 150 μm alumina (Al ₂ O ₃ ) film is formed by a water plasma spray method, and thereafter, A 150 μm ZrO ₂ film was formed on the film. The barium titanate was loaded on the tool material and heated at 1350 °C. After 60 hours, the temperature was lowered and the state of the film was observed. This operation is repeated until the film is peeled off. Peeling occurred locally after about 180 hours, so the old film was removed using a plane grinder and the film was reformed in the same manner as the method of initially forming the film.

After performing the same heating test again, it was found to be issued at 240 hours. Since the peeling was performed, it was confirmed that the film had durability equal to or higher than that of the first film.

(Comparative Example 4)

After the surface of the normal-pressure sintered SiC substrate having a porosity of 0% was chemically etched and roughened, a 150 μm aluminum oxide film was formed by the same water plasma spray method as in Example 1, and thereafter A 150 μm ZrO ₂ film was formed on the film. The same heating test as in Example 1 was carried out, and peeling occurred after 120 hours. There is no damage such as cracking or warping on the substrate, so try to reuse it.

The old film and the old ceria layer were removed by a flat grinder, and a new film was attempted in the same manner as the method of initially forming the film. However, since the surface roughness of the substrate was not sufficient, the film could not be formed.

Fig. 1 is a cross-sectional structural view showing a film formed on a porous SiC substrate used in a method for regenerating a tool material of the present invention.

Fig. 2 is a cross-sectional structural view showing a film formed on a porous SiC substrate used in a method for regenerating a tool material of the present invention.

Claims (13)

A tool material for firing a multilayer ceramic capacitor, comprising: a SiC substrate; and an SiO ₂ layer formed on the surface of the SiC substrate by oxidation treatment; and a viewing aperture of the tool material for firing the multilayer ceramic capacitor The degree is 15% or more, the specific gravity is 3.05 to 3.20, and the SiC content is 90% by weight or more; and ZrO _{2 is} formed on the surface of the SiO ₂ layer on which at least a portion of the multilayer ceramic capacitor as the fired material is placed. Or a coating layer of at least one of Al ₂ O ₃ . A tool material for firing a multilayer ceramic capacitor, comprising: a SiC substrate; and an SiO ₂ layer formed on the surface of the SiC substrate by oxidation treatment; and a viewing aperture of the tool material for firing the multilayer ceramic capacitor a degree of 15% or more, an apparent specific gravity of 3.05 to 3.20, a SiC content of 90% by weight or more, and a surface containing the ZrO ₂ on the surface of the SiO ₂ layer on which at least a portion of the multilayer ceramic capacitor as a fired material is placed. Or at least one of Al ₂ O ₃ and a coating layer formed by a sputtering method; and between the SiO ₂ layer and the coating layer, Al ₂ O ₃ or Al ₂ O ₃ -SiO is formed ₂ of at least either one of the intermediate layer. A tool material for firing a multilayer ceramic capacitor, comprising: a SiC substrate; and an SiO ₂ layer formed on the surface of the SiC substrate by oxidation treatment; and a viewing porosity of the tool material for firing the multilayer ceramic capacitor 15% or more, depending on the specific gravity of 3.05 ~ 3.20, SiC content of not less than 90% by weight; SiO with respect to the total content of the SiC substrate and the SiC layer ₂ of the above-described SiO _2, SiO ₂ layer of the above-described SiO The content of ₂ is 1 to 4% by weight; at least one of ZrO ₂ or Al ₂ O ₃ is formed on the surface of the SiO ₂ layer on which at least a portion of the multilayer ceramic capacitor as the object to be fired is placed. Covered layer. A tool material for firing a ceramic capacitor according to the present invention, comprising: a SiC substrate; and an SiO ₂ layer formed on the surface of the SiC substrate by oxidation treatment; and a viewing porosity of the tool material for firing the multilayer ceramic capacitor 15% or more, depending on the specific gravity of 3.05 ~ 3.20, SiC content of not less than 90% by weight; SiO with respect to the total content of the SiC substrate and the SiC layer ₂ of the above-described SiO _2, SiO ₂ layer of the above-described SiO The content of ₂ is 1 to 4% by weight; and at least one of ZrO ₂ or Al ₂ O ₃ is contained on the surface of the SiO ₂ layer on which at least a portion of the multilayer ceramic capacitor as the object to be fired is placed. And a coating layer formed by a sputtering method; and an intermediate layer containing at least one of Al ₂ O ₃ or Al ₂ O ₃ —SiO ₂ is formed between the SiO ₂ layer and the coating layer. A method for producing a tool material for firing a multilayer ceramic capacitor, comprising: adding an organic binder having a residual carbon ratio of less than 5.0% by weight after sintering to a raw material of SiC powder, and mixing to obtain a mixed powder a step of obtaining a porous formed body by kneading and molding after adding water to the mixture; and sintering the porous formed body at a temperature of 1500 ° C or higher and 2400 ° C or lower to obtain a sintered body; In the oxygen atmosphere having a concentration of 2% or more, the sintered body is fired at a temperature of 1350 ° C or higher and 1650 ° C or lower for 1 hour or longer and 6 hours or shorter to form an SiO ₂ layer on the surface of the sintered body; A step of forming a coating layer containing at least one of ZrO ₂ or Al ₂ O ₃ on the surface of the SiO ₂ layer by a sputtering method. A method for regenerating a tool material for firing a multilayer ceramic capacitor, characterized in that the material for firing the laminated ceramic capacitor according to claim 1 is reproduced; and the method for regenerating the tool material for firing the multilayer ceramic capacitor is After the polishing tool material is used several times, the method includes the steps of: removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate; and re-forming the SiO ₂ layer on the surface of the SiC substrate; And forming a thickness of 30 μm or more and 500 μm or less on the surface of the reformed SiO ₂ layer, and at least one of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ Or a plurality of steps of coating the main component. A method for regenerating a tool material for firing a multilayer ceramic capacitor, characterized in that the material for firing the laminated ceramic capacitor according to claim 2 is reproduced; and the method for regenerating the tool material for firing the multilayer ceramic capacitor is After the polishing tool material is used several times, the method includes the steps of: removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate; and re-forming the SiO ₂ layer on the surface of the SiC substrate; And forming a thickness of 30 μm or more and 500 μm or less on the surface of the reformed SiO ₂ layer, and at least one of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ Or a plurality of steps of coating the main component. A method for regenerating a tool material for firing a multilayer ceramic capacitor, characterized in that the material for firing the laminated ceramic capacitor according to claim 1 is reproduced; and the method for regenerating the tool material for firing the multilayer ceramic capacitor is After the baking tool material is used several times, the method includes the steps of removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate, and heating at a temperature of 1350 ° C or higher in an oxidizing atmosphere for 2 hours or longer. a step of re-forming the SiO ₂ layer on the surface of the SiC substrate; and forming a thickness of 30 μm or more, 500 μm or less, and Al ₂ O on the surface of the reformed SiO ₂ layer _3. A step of coating at least one of ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ or a plurality of coating layers as a main component. A method for regenerating a tool material for firing a multilayer ceramic capacitor, characterized in that the material for firing the laminated ceramic capacitor according to claim 2 is reproduced; and the method for regenerating the tool material for firing the multilayer ceramic capacitor is After the baking tool material is used several times, the method includes the steps of removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate, and heating at a temperature of 1350 ° C or higher in an oxidizing atmosphere for 2 hours or longer. a step of re-forming the SiO ₂ layer on the surface of the SiC substrate; and forming a thickness of 30 μm or more, 500 μm or less, and Al ₂ O on the surface of the reformed SiO ₂ layer _3. A step of coating at least one of ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ or a plurality of coating layers as a main component. A method for regenerating a tool material for firing a multilayer ceramic capacitor, characterized in that the material for firing the laminated ceramic capacitor according to claim 1 is reproduced; and the method for regenerating the tool material for firing the multilayer ceramic capacitor is After the polishing tool material is used several times, the method includes the steps of removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate by bead blasting or planar polishing; in an oxidizing environment a step of heat-treating at a temperature of 1350 ° C or higher for 2 hours or more to re-form a SiO ₂ layer on the surface of the SiC substrate; and a thickness of 30 μm on the surface of the reformed SiO ₂ layer The step of coating a layer containing at least one or a plurality of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ as a main component, preferably 500 μm or less. A method for regenerating a tool material for firing a multilayer ceramic capacitor, characterized in that the material for firing the laminated ceramic capacitor according to claim 2 is reproduced; and the method for regenerating the tool material for firing the multilayer ceramic capacitor is After the polishing tool material is used several times, the method includes the steps of removing the SiO ₂ layer and the coating layer formed on the surface of the SiC substrate by bead blasting or planar polishing; in an oxidizing environment a step of heat-treating at a temperature of 1350 ° C or higher for 2 hours or more to re-form a SiO ₂ layer on the surface of the SiC substrate; and a thickness of 30 μm on the surface of the reformed SiO ₂ layer The step of coating a layer containing at least one of a plurality of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —SiO ₂ , and ZrSiO ₄ as a main component, and 500 μm or less. The method for regenerating a tool material for firing a multilayer ceramic capacitor according to any one of claims 6 to 11, wherein in the step of reforming the coating layer, plasma spraying, gas deposition, vapor deposition or chemical gas is used. A combination of any one or a plurality of phase depositions (CVD). The method for regenerating a tool material for firing a multilayer ceramic capacitor according to any one of claims 6 to 11, wherein the step of reforming the coating layer is followed by heating to a temperature of 1400 ° C or higher and then baking.