JP3117433B2 - Manufacturing method of multilayer ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated ceramic which is excellent in mechanical properties such as strength, and which is suitable as a mechanical component material having oxidation resistance and corrosion resistance at high temperatures.

[0002]

2. Description of the Related Art A non-oxide ceramic sintered body containing silicon carbide (SiC) as a main component has excellent mechanical properties such as high strength and high toughness. Further, since it has excellent heat resistance that can withstand temperatures up to 1000 ° C., it is widely used as a mechanical part or the like.

However, parts manufactured from the above-mentioned non-oxide ceramics sintered compacts are used at 1200 ° C. like gas turbine parts.
When used as components used at the above high temperatures, the oxidation resistance and corrosion resistance are not sufficient. In particular, when the temperature reaches about 1500 ° C. or higher, deterioration due to the progress of oxidation is inevitable. This is because alumina or the like is used as a sintering aid in the production of a silicon carbide sintered body, so that the grain boundary phase is oxidized or corroded.

[0004] On the other hand, oxide ceramics are excellent in oxidation resistance and corrosion resistance, but their strength at high temperatures is remarkably reduced. That is, non-oxide ceramics and oxide ceramics alone cannot satisfy both high strength and heat resistance, and oxidation resistance and corrosion resistance at high temperatures.

[0005] Therefore, if an oxide ceramic layer is formed on the surface of non-oxide ceramic, it is expected that the oxidation resistance and the corrosion resistance will be improved, and that the material will be a mechanical component material that can withstand use at high temperatures.

[0006] However, it is usually difficult to join and integrate the non-oxide ceramic and the oxide ceramic, and even if they are joined, they are immediately separated. Even in the case of joining, the heat treatment accompanying the integration operation causes tensile or compressive residual stress to occur in the cooling process due to the difference in physical properties between the two, especially the difference in the coefficient of thermal expansion. Often occurs. Therefore, it is difficult to integrate the non-oxide ceramic and the oxide layer by the conventional method.

In order to solve such a problem caused by the generation of residual stress, it is conceivable to stack oxide ceramics having a thermal expansion coefficient close to that of non-oxide ceramics. And the general formula: RE
It is clear that a rare earth silicate compound represented by ₂ SiO ₅ (wherein RE is a rare earth element selected from the group consisting of Y, Yb, Er and Dy) can be integrated using alumina. (JP-A-8-240652). In this ceramic laminate, an interface reaction layer is formed during sintering.

[0008]

However, when the above-described laminated material composed of a rare earth silicate compound and silicon carbide ceramics integrated by alumina is maintained at a high temperature exceeding 1500 ° C., gas is generated from the interface reaction layer. Problems such as separation at the interface and swelling of the rare earth silicate compound layer occur.
Therefore, the heat resistant temperature of the interface reaction layer determines the heat resistant temperature of the entire laminate. Since the heat resistant temperature of the interface reaction layer varies depending on the kind of the rare earth element, the rare earth element may be selected so as to increase the heat resistant temperature of the interface reaction layer in order to improve the heat resistant temperature of the laminate.

However, the coefficient of thermal expansion of the rare earth silicate compound varies depending on the type of the rare earth element. The change in the coefficient of thermal expansion of the rare earth silicate compound due to the rare earth element and the change in the heat resistance temperature of the interface reaction layer formed on the silicon carbide ceramics are described below. ,
It has been found that they have almost the same tendency. Therefore, when a rare earth silicate compound that forms an interface reaction layer having a high heat resistance temperature to increase the heat resistance temperature of the laminate is selected,
The coefficient of thermal expansion of the rare earth silicate compound layer also increases. Therefore,
The difference in the coefficient of thermal expansion between the silicon carbide layer and the rare earth silicate compound layer increases, and a tensile stress is generated on the surface of the rare earth silicate compound layer of the laminate. As a result, deterioration of the mechanical properties of the entire laminate is inevitable.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and provides a ceramic laminate mainly composed of silicon carbide having strength, toughness and oxidation resistance at a high temperature exceeding 1500 ° C. It is intended to provide.

Another object of the present invention is to provide a mechanical component material which can sufficiently cope with corrosion at high temperatures.

[0012]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and as a result, formed a rare earth silicate compound layer which is bonded and integrated with silicon carbide ceramics using different rare earth silicate compound compounds. By forming the two layers to form an interface reaction layer having a high heat resistance temperature,
In addition, they have found that the problem of tensile stress generated on the surface of the rare earth silicate compound layer can be solved, and have achieved the multilayer ceramics of the present invention.

The method for producing a laminated ceramic according to the present invention comprises:
First layer containing silicon carbide, alumina layer, general formula: RE
₂ SiO ₅ or RE ₂ Si ₂ O ₇ (However, RE in the formula
Represents a rare earth element selected from the group consisting of yttrium, ytterbium, erbium and dysprosium), and contains one rare earth silicate compound having a larger coefficient of thermal expansion among two rare earth silicate compounds having different rare earth elements from each other. A second layer, and a third layer containing the other rare earth silicate compound having a small coefficient of thermal expansion are sequentially laminated to form a laminate, and the first layer and the second layer are subjected to heat treatment. The gist is that the two layers and the third layer are joined and integrated by alumina.

The rare earth element of the one rare earth silicate compound contained in the second layer is an element selected from the group consisting of ytterbium, erbium and dysprosium, and the other rare earth element contained in the third layer is The rare earth element of the silicate compound can be yttrium.

The first layer is a sintered body layer obtained by previously molding and sintering a powder containing silicon carbide. The rare earth silicate compounds of the second and third layers are each composed of a rare earth oxide. It is generated by heating from a mixture of a substance and silicon oxide, and the heating temperature of the heat treatment can be 1400 to 1950 ° C.

Further, the temperature of the heat treatment can be 1750 ° C. or less.

According to the above method, the alumina is favorably first
By joining the layer and the second layer, and the tensile stress generated in the second layer is reduced by the third layer covering the second layer, the resulting laminated ceramic has heat resistance, strength, and acid resistance at high temperatures. Since it has both chemical resistance and corrosion resistance, it has the ability to withstand use as a structural material for manufacturing mechanical parts exposed to high temperatures.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Silicon carbide is a ceramic excellent in high-temperature strength. To improve oxidation resistance and corrosion resistance at this high temperature, a silicate compound of a rare earth element: RE ₂ SiO ₅
Or RE ₂ Si ₂ O ₇ (RE in the formula is Y, Yb, Er
And Dy are selected from the group consisting of Dy and Dy) to cover the surface of the silicon carbide. The above-mentioned silicate compound of a rare earth element (hereinafter, simply referred to as silicate in the present application) and silicon carbide cannot be integrated by simply heating to obtain a laminate. In order to bond the silicon carbide and the silicate, heat treatment is performed with alumina (Al ₂ O ₃ ) interposed between the silicon carbide layer and the silicate layer, so that the two layers are well bonded. At this time, an interface reaction layer is formed at the joint interface by a reaction product of alumina and silicate. It is necessary to select a silicate so that the heat resistance of the interface reaction layer can be secured. However, a tensile stress is generated on the surface of the silicate layer due to a difference in thermal expansion coefficient between the silicate and the silicon carbide.
In the present invention, another silicate layer (second silicate layer) having a smaller coefficient of thermal expansion than the silicate layer (first silicate layer) laminated adjacent to alumina is further laminated on the surface side of the first silicate layer. The first silicate layer causes a compressive stress to act on the second silicate layer, thereby relaxing the tensile stress generated on the surface side of the second silicate layer.

With the above configuration, the silicate forming the first silicate layer can be selected so that the heat resistance of the interface reaction layer is ensured, and the second silicate layer can be selected.
Since the tensile stress generated in the silicate layer can be eliminated by the first silicate layer, a ceramic laminate having both heat resistance and mechanical properties is provided.

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

Bonding of silicon carbide and silicate with alumina is achieved by heat treatment with an alumina thin layer interposed between the silicon carbide layer and the silicate layer. In the present invention, it is preferable that the silicon carbide layer, the first silicate layer, and the second silicate layer that are joined to obtain a laminate are formed bodies. These compacts may be any of a compact obtained by press-molding the powder and a sintered body further subjected to a sintering process. For example, a silicon carbide powder, an alumina powder, a first silicate layer Forming silicate (first)
(Laminated silicate) powder and a silicate (second silicate) powder forming a second silicate layer in a layered form, and simultaneously press-molded a laminated green compact, a silicon carbide sintered body or a green compact, and first and second green compacts. A material in which an alumina powder is sandwiched between a sintered body having a silicate layer or a green compact or the like can be used. The compact density of the compact can be appropriately set according to operational necessity and the like. However, in consideration of easiness of handling and densification at the time of sintering, silicon carbide has a density of 1.3 to 1.3.
It is preferable to mold to about 1.9 g / cm ³ . A sintered body of silicon carbide and silicate is obtained by heating each green compact to a sintering temperature. The sintering temperature of silicon carbide and silicate varies depending on the presence or absence or composition of a sintering aid, but generally, the sintering temperature of silicon carbide is around 2000 ° C, and the sintering temperature of silicate is around 1400 to 1750 ° C. . The atmosphere for sintering may be normal pressure or reduced pressure, and pressure sintering such as hot pressing or hot isostatic pressing (HIP) may be performed.

As described above, for the first silicate, a silicate having a high heat-resistant temperature of the interface reaction layer to be formed is selected, and for the second silicate, a silicate having a smaller thermal expansion coefficient than the first silicate is used. select. In the case of monosilicate and disilicate having the same rare earth element, the disilicate has a smaller coefficient of thermal expansion, but the different rare earth element has a higher heat resistance of the interfacial reaction layer and a thermal expansion of the silicate than in the case of different silicate types. Since the difference in the coefficients is much larger, the determination of the rare earth element is important in selecting the first silicate and the second silicate. The heat resistance temperature of the interface reaction layer is highest when the rare earth element of the rare earth silicate compound is erbium, followed by ytterbium, dysprosium, and yttrium. On the other hand, the coefficient of thermal expansion of the rare earth silicate compound is smallest when the rare earth element is yttrium, and then increases in the order of dysprosium, ytterbium, and erbium.
Therefore, when erbium silicate is used as the first silicate and yttrium silicate is used as the second silicate, the combination has the highest heat resistance and maximizes the compressive stress of the second silicate layer.

Regarding the first and second silicates, silicates can also be formed by heating a mixture of a rare earth oxide and silicon dioxide (SiO ₂ ) to react the rare earth oxide with silicon oxide. In the above, in place of the silicate green compact, rare earth oxide powder: RE ₂ O ₃
(Wherein RE in the formula represents a rare earth element selected from the group consisting of Y, Yb, Er and Dy), and a mixed green compact of silicon dioxide powder may be used. By heating the mixed green compact to the silicate sintering temperature, silicate is generated and sintering proceeds at the same time. When the mixing ratio (molar ratio) of the rare earth oxide and silicon dioxide is 1: 1, RE ₂ SiO ₅ type silicate (referred to as monosilicate) is generated,
In the case of 1: 2, RE ₂ Si ₂ O ₇ type silicate (referred to as disilicate) is generated, so that the mixing ratio may be appropriately adjusted according to the silicate to be generated. Monosilicate has higher resistance to oxidation because it is easier to form a denser layer than disilicate. For this reason, it is one effective form to use a monosilicate type having high oxidation resistance as the first silicate and a disilicate type having a small thermal expansion coefficient as the second silicate.

Since the silicon carbide ceramic has conductivity, when the silicon carbide ceramic is put into an alumina suspension and a negative voltage is applied to the silicon carbide ceramic, the alumina particles are attracted to the surface of the silicon carbide ceramic by an electrophoretic effect. And an alumina thin layer is formed. Therefore, if the first silicate / second silicate stacked green compact is brought into contact with the silicon carbide ceramic having the alumina thin layer formed by such a method and the heat treatment is performed, the silicate layer and the silicon carbide layer are joined by alumina. The resulting laminated ceramic is obtained. The formation of the alumina layer by the electrophoresis effect
It is suitable for forming a thin alumina layer having a thickness of several hundred μm or less, and the thickness of the formed alumina layer can be easily controlled by adjusting the voltage application time. Further, even when the bonding interface is a curved surface, a uniform alumina layer can be formed.
Alternatively, it may be applied by appropriately selecting and applying from a lamination method such as a lamination method of depositing and depositing using a dipping method, a sol-gel method, a CVD method or the like, or a lamination method by sheet formation.

The thicknesses of the first silicate layer and the second silicate layer may be determined in consideration of the balance of the stress acting between the first silicate layer and the second silicate layer in the integrated laminated ceramic. Preferably, in order to ensure the strength of the layer itself, an excessively thick layer having a thickness of about 10 μm or more takes into account that a partial stress difference in the layer is likely to occur.
It is about μm or less.

As described above, the silicon carbide layer, the first silicate (or a mixture of a rare earth oxide and silicon oxide that forms the first silicate) layer and the second silicate (or the rare earth oxide and silicon oxide that form the second silicate) Mixture with)
The layers are laminated and heat-treated so that alumina is interposed between the silicon carbide layer and the first silicate layer, whereby the whole is integrated, and the first silicate layer on the inner side and the second silicate layer on the surface side are integrated.
A silicon carbide ceramic laminate covered with the silicate layer is obtained. A part of the interposed alumina reacts or forms a solid solution with the silicon carbide and the silicate by heating, acts as an adhesive on the silicon carbide layer and the silicate layer, and joins the silicon carbide layer and the silicate layer. At this time, an interface reaction layer is formed by the alumina and the silicate.
If the amount of alumina used is excessive, a thick alumina layer is formed on the laminate after the heat treatment, and a crack is generated in the alumina layer due to a difference in a thermal expansion coefficient between silicate or silicon carbide and alumina, so that the alumina layer is easily broken. Become. Therefore,
In order to prevent an alumina layer thicker than 150 μm from being formed on the laminated ceramic after the heat treatment,
It is desirable to adjust the amount of alumina used so that: In practice, 0.06 g /
It is preferable that the layers are laminated at a ratio of not more than cm ² .

The bonding between the silicon carbide layer and the silicate layer is performed at a temperature of about 1400 ° C. or higher, preferably about 1 ° C., when bonding the silicon carbide sintered body and the silicate sintered body.
This is achieved by a heat treatment at 550 to 1750 ° C.
On the other hand, when the silicon carbide and the silicate to be joined are green compacts, it is necessary to set the temperature of the heat treatment so that the green compact is simultaneously sintered during the heat treatment. Therefore,
The temperature suitable for the heat treatment for bonding varies depending on whether both layers are bonded. When silicon carbide is a green compact, silicon carbide has a higher melting point than silicate. Therefore, in order to enable heat treatment at a low temperature of 1950 ° C. or less, for example, about 1750 to 1850 ° C., silicon carbide is used. It is necessary to set conditions that allow sintering at a low temperature and to use a sintering aid. In this regard, it is advantageous that the silicon carbide to be joined is a sintered body pre-sintered, and a laminated green compact in which the first silicate layer and the second silicate layer are laminated, and an alumina powder laminated in the surface. The form in which the silicon carbide sintered body is brought into contact with and heated is practically simple. In this mode, 1400
By heating at about 1750 ° C. for about 0.5 to 2 hours, a laminated ceramics which is easily joined and integrated can be easily obtained, which is practical.

In the present invention, commonly used additives such as a sintering aid and a lubricant can be used in accordance with a general method, and a layer containing silicon carbide and silicate as main components, respectively, can be used. Good bonding to each other. For example,
About 10% by volume or less of alumina or the like can be added as a sintering aid. For the silicon carbide layer, a suitable laminated ceramic can be obtained by the method of the present invention using a fiber reinforced material such as whisker or long fiber or a spherical, plate-like or flake-like particle material as a composite material.

One embodiment of a manufacturing method for manufacturing a laminated ceramic according to the above will be described below.

First, alumina is laminated by electrophoresis to a thickness of 1 to 50 μm on the surface of a silicon carbide ceramic obtained by sintering a silicon carbide compact. The thickness of the alumina is controlled by adjusting the distance between the electrodes, the voltage, and the energizing time.

Next, the rare earth oxide and silicon dioxide are first
Weigh the silicate so that the silicate is produced, and n
Mixing with butanol as a dispersion medium by a ball mill using nylon balls. After mixing, the mixture is dried by a rotary evaporator, and the particle size is adjusted using a 500 μm sieve to obtain a first mixed powder for producing a first silicate. By the same operation, a second mixed powder for producing the second silicate is obtained.

After filling a predetermined amount of the first mixed powder into the mold and flattening the upper surface, the second mixed powder is further filled and deposited on the first mixed powder. The first and second mixed powders filled in the mold are uniaxially pressed at a pressure of about 10 to 100 MPa to form a compact. The compact is placed on an inert gas such as nitrogen and placed on a silicon carbide ceramic so that the mixed powder 1 of the compact and the above-mentioned alumina of the silicon carbide ceramic are in contact with each other. 1400-1
Heat treatment is performed at a temperature of 700 ° C. for about 0.5 to 2 hours to obtain a laminated ceramic in which the silicon carbide ceramic and the silicate laminate are integrated. The formation of the first silicate layer and the second silicate layer by the reaction between the rare earth oxide and silicon dioxide in the obtained laminated ceramics is confirmed by identification of the constituent layers using X-ray diffraction measurement or the like.

The laminated ceramics joined by the heat treatment is a stable laminate with little generation of residual stress due to a difference in thermal expansion coefficient. However, in order to prevent the occurrence of cracks due to a rapid temperature change, the heat treatment is performed. The subsequent cooling is preferably performed gently.

[0034]

The present invention will be described below in more detail with reference to experimental examples.

Example 1 A suspension was prepared by dispersing alumina in ethanol, silicon carbide ceramics and a carbon plate used as a counter electrode were immersed in the suspension, and a voltage of 50 V was applied between them. The surface of the silicon carbide ceramics was covered with alumina having a thickness of about 20 μm by electrophoresis.

Further, 1 mol% of erbium oxide powder having an average particle diameter of 1 μm and 1 mol% of silicon dioxide powder having an average particle diameter of 0.8 μm were mixed in a ball mill using nylon balls, using n-butanol as a dispersion medium. Then, it dried using the rotary evaporator and prepared the 1st mixed powder.
The same operation as the preparation of the first mixed powder was repeated using 1 mol% of yttrium oxide powder having an average particle diameter of 1 μm and 1 mol% of silicon dioxide powder having an average particle diameter of 0.8 μm to obtain a second mixed powder. I got

0.3 g of the first mixed powder obtained in a mold having a bottom surface of 12 mm × 36 mm was charged and the top surface was leveled.
Similarly, 0.2 g of the second mixed powder was charged and flatly filled. The powder in the mold was uniaxially pressed at a pressure of 30 MPa to form a molded body.

The compact was placed on the silicon carbide ceramic so that the first mixed powder of the obtained compact was in contact with the alumina on the surface of the silicon carbide ceramic, and the pressure was 0.1 MPa.
Temperature in an argon atmosphere at a rate of 10 ° C./min.
Hot press sintering was performed for 1 hour at a sintering temperature of 50 ° C. and a press pressure of 30 MPa. Thus, a ceramic laminate was obtained.

Using the obtained ceramic laminate, measurements for evaluating strength, oxidation resistance and heat resistance were performed. For the evaluation of the strength, a three-point bending strength was measured in accordance with the provisions of JIS 1601. For the evaluation of oxidation resistance,
10 layers of ceramic laminate in air at 1500 ° C
A change in weight after being left for 00 hours was measured. Regarding heat resistance, the ceramic laminate was cut in a direction perpendicular to the layer, the cut surface was exposed to a helium atmosphere, and the TG curve was measured when the temperature was raised to 1700 ° C. Was. Table 1 shows the measurement results.

Example 2 The same operation as in Example 1 was repeated except that 1 mol% of ytterbium oxide having an average particle size of 1 μm was used instead of the erbium oxide powder used for preparing the first mixed powder. Laminated ceramics were prepared, and measurements for evaluating strength, oxidation resistance, and heat resistance were performed. Table 1 shows the measurement results.

Example 3 The same operation as in Example 1 was performed except that 1 mol% of dysprosium oxide having an average particle size of 1 μm was used instead of the erbium oxide powder used for preparing the first mixed powder. A multilayer ceramic was repeatedly produced, and measurements for evaluating strength, oxidation resistance, and heat resistance were performed. Table 1 shows the measurement results.

(Comparative Example 1) The second mixed powder was used without using the first mixed powder.
A laminated ceramic was produced by repeating the same operation as in Example 1 except that a molded body of only the mixed powder was produced, and measurements for evaluating strength, oxidation resistance and heat resistance were performed. Table 1 shows the measurement results.

(Comparative Example 2) The first mixed powder was used without using the second mixed powder.
A laminated ceramic was produced by repeating the same operation as in Example 1 except that a molded body of only the mixed powder was produced, and measurements for evaluating strength, oxidation resistance and heat resistance were performed. Table 1 shows the measurement results.

(Comparative Example 3) Example 1 was repeated except that the compact was placed on silicon carbide ceramics and subjected to hot press sintering so that the second mixed powder of the compact was in contact with alumina on the surface of silicon carbide ceramics. The same operation was repeated to produce a laminated ceramic, and measurements for evaluating strength, oxidation resistance and heat resistance were performed. Table 1 shows the measurement results.

[0045]

Table 1 3-point bending strength Weight change Weight loss onset temperature (MPa) (mg / mg cm < ² >) ([deg.] C)------------------------Example 1 520 2.5 1610 Example 2 530 0. 8 1580 Example 3 500 1.2 1570 Comparative Example 1 510 3.1 1520 Comparative Example 2 390 1.3 1610 Comparative Example 3 400 2.7 1520--------------------------------------------------------------------------------------- −−−−−−−−−−−−−−−−−

When the cross section of the laminated ceramics of Example 1 was observed with a microscope, the bonding interface was tightly integrated.
2 shows a layer structure as schematically shown in FIG. When the constituent phases were identified by X-ray diffraction measurement, it was confirmed that the erbium monosilicate layer 3 and the yttrium monosilicate layer 4 were formed on the silicon carbide ceramic 1 via the interface reaction layer 2. In Examples 2 and 3,
The laminated ceramic had the same structure as that of FIG. 1 except that an ytterbium monosilicate layer or a dysprosium monosilicate layer was formed instead of the erbium monosilicate layer 3. On the other hand, as shown in FIG.
The yttrium monosilicate layer 4 was formed thereon, and it was confirmed that the multilayer ceramic of Comparative Example 2 had the erbium monosilicate layer 3 formed on the silicon carbide ceramic 1 as shown in FIG. In Comparative Example 3,
It was confirmed that the yttrium monosilicate layer 4 and the erbium monosilicate layer 3 were formed on the silicon carbide ceramic 1 via the interface reaction layer 5.

Further, as shown in Table 1, the change in weight at 1500 ° C. was slight in any of the laminated ceramics of Examples 1 to 3 and Comparative Examples 1 to 3, and was considered to be within the error range. It turns out that it has oxidation resistance.

On the other hand, the heat resistance of the laminated ceramics, that is, the heat resistance of the interface reaction layer in the laminated ceramics, can be evaluated using a TG curve measured during a temperature rise by exposing a cross section of the laminated ceramics to an inert gas atmosphere. it can. Specifically, the weight loss due to the generation of gas from the interface reaction layer by heating appears in the TG curve during the temperature rise process.
The heat resistance of the interface reaction layer can be evaluated based on the onset temperature of the weight loss determined from the TG curve.

As is clear from Table 1, Example 1 having the first silicate layer and the second silicate layer according to the present invention.
Each of the laminated ceramics of Nos. 1 to 3 has a high weight loss starting temperature, high heat resistance, and a three-point bending strength exceeding 500 MPa. On the other hand, in Comparative Example 1 having no first silicate layer, the temperature at which weight loss starts was low because the heat resistance of the interface reaction layer made of the second silicate was low. In Comparative Example 2 having no second silicate layer, the three-point bending strength is extremely low because the tensile stress generated in the first silicate layer is not reduced.
Further, in Comparative Example 3 in which the first silicate layer and the second silicate layer are arranged in reverse, the heat resistance of the interface reaction layer due to the second silicate is low, and the tensile stress generated in the first silicate layer is reduced. Both unacceptable drawbacks appear in the measurement results.

[0050]

As described above, the method for producing a laminated ceramic according to the present invention can provide a laminated ceramic having excellent heat resistance, strength and oxidation resistance at high temperatures, and its industrial value is extremely large. It is. Moreover, the laminated ceramics obtained by the production method of the present invention is suitable as a material for mechanical parts used at high temperatures due to its excellent heat resistance and strength, and can supply high quality mechanical parts.

[Brief description of the drawings]

FIG. 1 is a schematic view schematically showing a layer structure obtained by microscopic observation of a cross section of a laminated ceramic (Example 1) according to the present invention.

FIG. 2 is a schematic diagram schematically showing a layer structure obtained by microscopic observation of a cross section of the laminated ceramic of Comparative Example 1.

FIG. 3 is a schematic diagram schematically showing a layer structure obtained by microscopic observation of a cross section of the laminated ceramic of Comparative Example 2.

FIG. 4 is a schematic diagram schematically showing a layer structure obtained by microscopic observation of a cross section of the multilayer ceramic of Comparative Example 3.

[Explanation of symbols]

 Reference Signs List 1 silicon carbide ceramics 2, 5 interface reaction layer 3 erbium monosilicate layer 4 yttrium monosilicate layer

Continuation of the front page (56) References JP-A-10-87364 (JP, A) JP-A-58-125667 (JP, A) JP-A-2-296770 (JP, A) JP-A-7-277861 (JP, A) JP-A-10-87386 (JP, A) JP-A-11-12050 (JP, A) JP-A-11-139891 (JP, A) JP-A-11-139883 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 37/00 B32B 18/00 C04B 41/89

Claims (3)

(57) [Claims] 1. A first layer containing silicon carbide, an alumina layer, a general formula: RE ₂ SiO ₅ or RE ₂ Si ₂ O _7.
(However, RE in formulas, ytterbium, erbium and dysprosium shows a rare earth element selected from the group consisting um) second containing a rare earth silicate compound you express in
Layer and general formula: Y ₂ SiO ₅ or Y ₂ Si ₂ O
No. 3 containing the yttrium silicate compound represented by ₇
Forming a laminate in which layers are sequentially laminated, and subjecting the laminate to heat treatment so that the first layer, the second layer, and the third layer are joined and integrated with alumina. Manufacturing method of ceramics. 2. The first layer is a sintered body layer obtained by previously molding and sintering a powder containing silicon carbide, and the rare earth silicate compounds of the second layer and the third layer are each a rare earth silicate compound. oxide and produced by heating a mixture of silicon dioxide, the production method according to claim 1 heating temperature of the heat treatment is 1,400 to 1,950 ° C.. 3. A process according to claim 1 or 2 temperature is 1750 ° C. or less of the heat treatment.