JP7138906B2 - Ceramic sintered body, glass molded article and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to ceramic sintered bodies and glass moldings having metallic luster, and methods for producing them.

Bizen ware is widely known as one of the representative ceramics of Japan. One of the characteristics of Bizen ware is that it does not use glaze. The pattern of Bizen ware can be changed by changing the position where the molded product is placed when fired in the kiln, or by using rice straw or ash. Using these characteristics, pottery with various patterns is produced. Among them, the pattern with a golden metallic luster is called “Kinsai” and is highly prized for its design. The appearance of such "kinsai" is rare, and the exact conditions for obtaining the pattern were unknown.

On the other hand, a method of adding "golden color" using a glaze is known (for example, Patent Document 1). However, since an expensive glaze containing gold, silver, palladium, etc. is required, the cost is inevitably high.

JP-A-8-119772

The present invention has been made to solve the above problems, and an object of the present invention is to provide a ceramic sintered body and a glass molded article having metallic luster and excellent design. Another object of the present invention is to provide a simple method for producing such ceramic sintered bodies and glass moldings.

The above-mentioned problem is a ceramic sintered body in which a glass layer and an iron oxide layer are formed on the surface of a ceramic base material, the iron oxide layer is formed on the surface of the glass layer, and the iron oxide layer is formed by: formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0 to 0.2. ]
Ceramics having a metallic luster, comprising α-iron oxide optionally substituted with aluminum represented by and wherein the c-axis of the α-iron oxide in the iron oxide layer is parallel to the surface of the ceramic base. It is solved by providing a sintered body.

At this time, it is preferable that the glass layer has a thickness of 1 to 1000 μm and the iron oxide layer has a thickness of 10 to 500 nm. It is also preferred that x is greater than or equal to 0.05.

A plate made of α-iron oxide in which a composite layer is further formed on the surface of the iron oxide layer, and the composite layer may be substituted with aluminum represented by the above formula (1) in a glass matrix. The thickness direction of the plate-like body is the c-axis of the α-iron oxide, and the c-axis of the α-iron oxide in the plate-like body is parallel to the surface of the ceramic base. is also preferred. At this time, it is more preferable that the thickness of the composite layer is 10 to 500 nm.

At this time, it is also preferable that the glass layer and the glass matrix are made of alkali silicate glass.

Porcelain and building materials comprising the ceramic sintered body are preferred embodiments of the ceramic sintered body.

In the method for producing a ceramic sintered body, a ceramic base material containing 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ is heated to 1100° C. or higher in a gas atmosphere containing an alkali metal element. In the first step of forming a molten glass layer containing iron ions and alkali metal ions on the surface of the ceramic substrate, the ceramic substrate having the glass layer formed thereon is heated at 1100° C. or higher in a reducing atmosphere. a second step of reducing the iron ions in the glass layer by heat treatment; and a third step of heat-treating the ceramic substrate at 800 to 1000° C. in an oxidizing atmosphere to form the iron oxide layer. The method for producing the ceramics sintered body, which has the above, is also a preferred embodiment of the ceramics sintered body.

The above problem is a glass molded product having an iron oxide layer formed on the surface of a glass substrate, wherein the iron oxide layer is represented by the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0 to 0.2. ]
A glass having metallic luster, which is composed of α-iron oxide optionally substituted with aluminum represented by and in which the c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the glass substrate. It is also solved by providing a molded product.

In the above method for producing a glass molded article, a first step of forming molten glass by heating a glass raw material containing 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ to 1100 ° C. or higher, a second step of heat-treating the molten glass at 1100° C. or higher in a reducing atmosphere to reduce iron ions in the molten glass; and heat-treating the molten glass at 800 to 1100° C. in an oxidizing atmosphere. A preferred embodiment of the glass molded article is a method for manufacturing a glass molded article, which has a third step of forming the iron oxide layer by.

INDUSTRIAL APPLICABILITY The ceramic sintered body and glass molded article of the present invention have a metallic luster, particularly a golden metallic luster, and are excellent in design, so that they can be suitably used in various applications. Moreover, according to the production method of the present invention, such ceramic sintered bodies and glass molded articles can be produced easily.

1 is an appearance photograph of a ceramic sintered body in Example 1 and Comparative Example 1. FIG. 1 shows electron micrographs and elemental maps of cross sections of ceramic sintered bodies and electron diffraction patterns of iron oxide layers in Example 1 and Comparative Example 1. FIG. An enlarged view of the electron micrograph g in FIG. 2 is shown. 1 shows an electron micrograph of a cross section, an elemental map, and an electron diffraction pattern of a composite layer in Bizen ware of Reference Example 1. FIG. 1 is a transmission electron microscope image and an electron diffraction pattern of a portion containing an iron oxide layer and a composite layer in a ceramic sintered body of Example 1 and a portion containing a composite layer in Bizen ware of Reference Example 1. FIG. 1 shows a transmission electron microscope image of a portion containing an iron oxide layer and a composite layer and electron diffraction patterns of the iron oxide layer and the composite layer in the ceramic sintered body of Example 1. FIG. FIG. 10 is an appearance photograph of a ceramic sintered body before and after heat treatment in Example 5. FIG.

The ceramic sintered body of the present invention is obtained by forming a glass layer and an iron oxide layer on the surface of a ceramic substrate, wherein the iron oxide layer is formed on the surface of the glass layer, and the iron oxide layer is formed on the surface of the glass layer. is the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0 to 0.2. ]
Ceramics having a metallic luster, comprising α-iron oxide optionally substituted with aluminum represented by and wherein the c-axis of the α-iron oxide in the iron oxide layer is parallel to the surface of the ceramic base. It is a sintered body.

Such a ceramic sintered body can be obtained by, for example, a method of sintering a ceramic base material containing 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ under predetermined conditions. By sintering the ceramic base material under predetermined conditions, a glass layer is formed on the surface of the base material, and an iron oxide layer is formed on the surface of the glass layer.

The ceramic base material in the ceramic sintered body of the present invention preferably contains 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ . If the content of the iron element is less than 0.2% by mass, the iron oxide layer may not be sufficiently formed and metallic luster may not be obtained. The iron element content is more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. On the other hand, if the iron element content exceeds 5% by mass, the ceramic sintered body may become reddish and have a poor appearance. The iron element content is more preferably 4% by mass or less. In the ceramic base material, the iron element is contained as Fe ₂ O ₃ , Fe ₃ O ₄ , FeO, Fe, FeOOH, or the like.

Elements other than iron contained in the ceramic substrate include silicon, aluminum, potassium, sodium, titanium, calcium, and magnesium. These elements are preferably contained as oxides. Above all, it is preferable that the ceramic base contains silicon element as a main component. Here, the main component means the component contained most in the ceramic base. Moreover, it is also preferable that the ceramic base contains an aluminum element. The content of silicon element in the ceramic base is preferably 40% by mass or more, more preferably 50% by mass or more in terms of _SiO2 . On the other hand, the silicon element content is usually 95% by mass or less, preferably 85% by mass or less. The content of the aluminum element in the ceramic base is usually less than 40% by mass in terms of Al ₂ O ₃ , preferably 25% by mass or less. On the other hand, the aluminum element content in the ceramic base is preferably 12% by mass or more. When elements other than iron element, silicon element and aluminum element _are contained in the ceramic base material, their contents may be appropriately adjusted according to the application. is 4.0% by mass or less, the content of sodium element is 4.0% by mass or less in terms of Na ₂ O, the content of titanium element is 2.0% by mass or less in terms of TiO ₂ , and calcium The element content is 2.0% by mass or less in terms of CaO, and the content of magnesium element is 2.0% by mass or less in terms of MgO.

The shape of the ceramic substrate in the ceramic sintered body may be determined depending on the application, and is not particularly limited.

In the ceramic sintered body, the glass layer is formed on the surface of the ceramic base. The glass layer may be formed on at least part of the surface of the ceramic base. When a part of the surface is masked and the ceramic base material is sintered, the glass layer and the iron oxide layer are not formed on the masked part, and metallic luster does not appear. By using masking in this way, ceramic sintered bodies of various designs can be obtained.

The type of glass forming the glass layer is not particularly limited, but the glass layer is preferably made of alkali silicate glass. Further, it is more preferable that the alkali silicate glass contains an aluminum element. A glass layer made of alkali silicate glass can be easily formed by a method for producing a ceramic sintered body, which will be described later.

The thickness of the glass layer is preferably 1 to 1000 μm. If the thickness is less than 1 μm, metallic luster cannot be obtained, and the appearance of the ceramic sintered body may be poor. More preferably, the thickness is 3 μm or more. On the other hand, if the thickness exceeds 1000 μm, it takes a long time to form the glass layer, which may reduce productivity. The thickness is more preferably 500 µm or less, still more preferably 100 µm or less, and particularly preferably 50 µm or less.

In the ceramic sintered body, the iron oxide layer is formed on the surface of the glass layer. The iron oxide layer is represented by the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0 to 0.2. ]
It contains α-iron oxide optionally substituted with aluminum represented by as a main component. The iron oxide layer may contain a glass phase between the α-iron oxide crystals.

In the formula (1), x is 0 to 0.2. Good metallic luster can be obtained by setting x in such a range. From the viewpoint of obtaining a golden metallic luster with extremely high designability, it is preferable that x is 0.01 or more and that the iron oxide layer contains aluminum-substituted α-iron oxide as a main component. At this time, x is more preferably 0.05 or more.

In the ceramic sintered body, the c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the ceramic base. That is, the thickness direction of the iron oxide layer is perpendicular to the c-axis of the α-iron oxide. The c-axis direction of α-iron oxide can be determined by electron diffraction measurement.

The thickness of the iron oxide layer is not particularly limited as long as the effects of the present invention are not impaired, but is preferably 10 to 500 nm. If the thickness is less than 10 nm, metallic luster may not be obtained. The thickness is more preferably 20 nm or more. On the other hand, if the thickness exceeds 500 nm, the ceramic sintered body may become reddish and have a poor appearance. The thickness is more preferably 300 nm or less.

In the ceramic sintered body of the present invention, metallic luster is obtained by forming such an iron oxide layer on the surface of the glass layer. It has long been known that in Bizen ware, 'Kinsai', which has a golden metallic luster, rarely appears without the use of glaze. Until now, it was thought that such "kinsai" was caused by the interference color of a thin film formed by the carbon of the fuel adhering to the surface of the pottery. However, the correctness of such a mechanism was not confirmed, and the exact conditions for the appearance of "golden color" were also unknown. Therefore, the present inventors analyzed the "kinsai" that appears in Bizen ware, and found that the surface of the Bizen ware that has "kinsai" has a plate-like body made of aluminum-substituted α-iron oxide in the glass layer and glass matrix. It was confirmed that a composite layer was formed. Then, it became clear that the "golden color" that appears in Bizen ware is due to the golden color of the aluminum-substituted α-iron oxide and the reflection of light from the surface of the glass layer.

The inventors of the present invention have made further studies to reproduce the "kinsai" that appears in Bizen ware. It has been found that such a ceramic sintered body has good metallic luster while being formed. Even more surprisingly, the Bizen ware created by the artist is that the c-axis of the α-iron oxide forming the plate-like body is perpendicular to the surface of the ceramic substrate, whereas the ceramic sintering of the present invention In the solid, the c-axis of α-iron oxide is parallel to the surface of the ceramic substrate, and it was found that the two are different in this respect.

In the ceramic sintered body, a composite layer may be further formed on the surface of the iron oxide layer, and the composite layer may be substituted with aluminum represented by the above formula (1) in the glass matrix. It contains a plate-shaped body made of α-iron oxide, the thickness direction of the plate-shaped body is the c-axis of the α-iron oxide, and the c-axis of the α-iron oxide in the plate-shaped body is the ceramic base material. Parallel to the surface is preferred. By forming such a composite layer, the appearance of the ceramic sintered body is further improved.

In the composite layer, the glass matrix contains plate-shaped bodies made of α-iron oxide represented by the above formula (1), which may be substituted with aluminum. The thickness direction of the plate-like body is the c-axis of the α-iron oxide, and the c-axis of the α-iron oxide in the plate-like body is parallel to the surface of the ceramic base. As mentioned above, a composite layer having a plate-shaped body made of α-iron oxide in a glass matrix is also present in Bizen ware created by an artist. - the c-axis of the iron oxide, and the c-axis of the α-iron oxide in the plate is perpendicular to the ceramic substrate. Thus, the Bizen ware and the ceramic sintered body of the present invention are different in the thickness direction of the plate-like body and the direction of the c-axis of α-iron oxide in the plate-like body. The thickness direction of the plate-like body can be confirmed by observation with an electron microscope.

The type of glass forming the glass matrix in the composite is usually the same as the glass forming the glass layers.

The composite layer preferably has a thickness of 10 to 500 nm. More preferably, the thickness is 300 nm or less. It should be noted that it is not necessary for the plate-like body to exist uniformly over the entire composite layer, and it may be partially missing.

The ceramic sintered body has a CIE1976L ^* a ^* b ^* lightness index L ^* in a color space of 50 to 70, a chromaticness index a ^* of 0.5 to 10, and a chromaticness index b ^* of 10 to 30. is preferably A ceramic sintered body having a lightness index L ^* and a chromaticness index a ^* and b ^* within the above ranges is extremely excellent in design. Each index is determined by measuring the portion where the iron oxide layer is formed using a spectrophotometer.

_The method for producing the ceramic _sintered body of the present invention is not particularly limited. A first step of forming a molten glass layer containing iron ions and alkali metal ions on the surface of the ceramic base material by heating the ceramic base material to the above temperature, in a reducing atmosphere, the ceramic base material having the glass layer formed thereon. A second step of reducing iron ions in the glass layer by heat treatment at 1100° C. or higher, and a third step of forming the iron oxide layer by heat treatment at 800 to 1000° C. in an oxidizing atmosphere. It is preferably obtained by a method.

In the first step, the ceramic base is heated to form a molten glass layer containing iron ions and alkali metal ions on the surface of the ceramic base. The ceramic base material to be subjected to the first step must contain 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ . The iron oxide layer is formed by performing the first to third steps on such a ceramic substrate. Elements other than the iron element contained in the ceramic base material used in the first step include the same elements as those contained in the ceramic base material in the ceramic sintered body.

An inorganic powder containing 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ is used as the ceramic raw material powder used for producing the ceramic base material. Examples thereof include natural clays generally used in the production of ceramics and powders obtained by refining the clays and having an elemental iron content within the above range. Such powders are low cost and preferred. Moreover, what mixed suitably inorganic powders other than clay can also be used. Elements other than the iron element contained in the ceramic raw material powder include the same elements contained in the ceramic base material in the ceramic sintered body.

Various additives may be added to the ceramic raw powder as long as they do not impair the effects of the present invention. The content of these additives is usually 50 parts by mass or less, preferably 10 parts by mass or less, with respect to 100 parts by mass of the raw ceramic powder.

After adding additives to the ceramic raw material powder as necessary, the powder is formed into a predetermined shape to obtain an unsintered ceramic base material. Examples of methods for molding the powder at this time include a method of press-molding the powder, a method of adding an appropriate amount of water to the powder, kneading the mixture, and then molding the mixture. It is also possible to use a ceramic base material that has been sintered in advance in an atmosphere of a gas that does not contain an alkali metal element. For example, Bizen ware can be used as a ceramic base material.

A molten glass layer containing iron ions and alkali metal ions is formed on the surface of the ceramic substrate by heating the unsintered ceramic substrate thus obtained to 1100° C. or higher in a gas atmosphere containing an alkali metal element. form. By heating the ceramic substrate in a gas atmosphere containing an alkali metal element, the alkali metal element diffuses in the vicinity of the surface of the substrate, thereby easily forming a molten glass layer with a low glass transition point. it is conceivable that. Examples of the alkali metal element include potassium, sodium, lithium, etc. Among them, potassium and sodium are preferable, and potassium is more preferable.

A method of generating a gas containing an alkali metal element includes a method of heating an alkali metal salt together with a ceramic substrate. Specifically, an alkali metal salt is placed in a furnace used for heating the ceramic substrate. There is a method of arranging. By heating the alkali metal salt together with the ceramic substrate, the alkali metal is contained in the gas surrounding the ceramic substrate and diffuses and permeates from the surface of the ceramic substrate. Examples of the alkali metal salt include alkali metal carbonates, halides, nitrates, etc. Among them, alkali metal carbonates are preferable. The heating of the ceramic substrate in the first step may be performed in the air or in a reducing atmosphere similar to that in the second step described later, but the former is preferred from the viewpoint of simple operation.

In the first step, the ceramic base is heated to 1100° C. or higher. If the heating temperature is less than 1100°C, the molten glass layer may not be sufficiently formed. The heating temperature is preferably 1150° C. or higher. On the other hand, the heating temperature is usually 1300° C. or lower. As a method of heating the ceramic base material in the first step, there is a method of raising the temperature of the ceramic base material from room temperature to 1100° C. or higher at 0.1 to 10° C./min.

In the second step, the ceramic base on which the molten glass layer is formed is heat-treated at 1100° C. or higher in a reducing atmosphere to reduce iron ions in the glass layer. Specifically, Fe ³⁺ is reduced to Fe ²⁺ or Fe. By once reducing Fe ³⁺ in this manner, the iron oxide layer is formed in the subsequent third step. Examples of the method for heating the ceramic substrate in a reducing atmosphere include a method for heating the substrate in a mixed gas containing carbon monoxide. Although the content of carbon monoxide in the mixed gas at this time is not particularly limited, it is preferably 5% by volume or more.

In the second step, the processing temperature of the ceramic base material is 1100° C. or higher. If the treatment temperature is lower than 1100° C., Fe ³⁺ in the glass may not be sufficiently reduced. On the other hand, the treatment temperature is usually 1400° C. or lower, preferably 1300° C. or lower. The treatment time of the ceramic substrate is not particularly limited, but is usually 0.5 hours or longer. If the treatment time is less than 0.5 hours, Fe ³⁺ may not be sufficiently reduced. On the other hand, the treatment time is usually 24 hours or less.

In the third step, the iron oxide layer is formed by heat-treating the ceramic substrate at 800 to 1000° C. in an oxidizing atmosphere. As a result, the Fe ²⁺ and Fe once reduced in the second step are oxidized again, crystals of α-iron oxide are precipitated in the molten glass matrix, and the iron oxide layer and the composite layer are formed. It is considered to be a thing. Examples of the method of heat-treating the ceramic base material in an oxidizing atmosphere include a method of heat-treating the base material in the air. The iron oxide layer and the composite layer are formed by oxidizing the substrate with oxygen in the atmosphere.

In the third step, the processing temperature of the ceramic substrate is 800-1000.degree. If the treatment temperature is less than 800° C., the oxide layer may not be sufficiently formed. The treatment temperature is preferably 820° C. or higher, more preferably 870° C. or higher. On the other hand, if the treatment temperature exceeds 1000° C., the amount of α-iron oxide formed is excessively increased, and the resulting ceramic sintered body may be reddish and have a poor appearance. The treatment temperature is preferably 980° C. or lower, more preferably 930° C. or lower. The treatment time of the ceramic substrate is not particularly limited, but is preferably 0.1 to 4 hours. If the treatment time is less than 0.1 hour, the oxide layer may not be sufficiently formed. The treatment time is more preferably 0.5 hours or longer. On the other hand, if the treatment time exceeds 4 hours, the amount of α-iron oxide formed is excessively increased, and the resulting ceramic sintered body may be reddish and have a poor appearance. The treatment time is more preferably 3 hours or less.

The ceramic sintered body obtained in this way has a metallic luster, particularly a golden metallic luster, and is therefore excellent in design. Moreover, such a ceramic sintered body can be easily produced without using an expensive glaze. Therefore, the ceramic sintered body can be suitably used as tableware, arts and crafts, ceramics such as sanitary ware, building materials such as tiles, and the like. A preferred embodiment of the present invention is a ceramic ware and a building material comprising the ceramic sintered body.

The molded glass product of the present invention is a molded glass product in which an iron oxide layer is formed on the surface of a glass substrate, and the iron oxide layer is formed by the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0 to 0.2. ]
A glass having metallic luster, which is composed of α-iron oxide optionally substituted with aluminum represented by and in which the c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the glass substrate. It is a molded product. In the same manner as in the ceramic sintered body, in the glass molding, metallic luster is obtained by forming the iron oxide layer on the surface of the glass substrate.

It is preferable that the glass forming the glass substrate contains 0.2 to 5 mass % of iron element in terms of Fe ₂ O ₃ . Further, the content of the aluminum element in the glass substrate is usually 0 to 25% by mass, preferably 0.1 to 25% by mass, in terms of Al ₂ O ₃ . Although the type of glass forming the glass substrate is not particularly limited, alkali silicate glass and lead glass are preferred.

The shape of the glass substrate in the glass molded article may be determined according to the application, and is not particularly limited.

In the glass molded article, an iron oxide layer similar to that formed in the ceramic sintered body is formed on the surface of the glass substrate. The iron oxide layer may be formed on at least part of the surface of the glass substrate.

In the glass molded product, a composite layer may be further formed on the surface of the iron oxide layer, and the composite layer may be substituted with aluminum represented by the above formula (1) in the glass matrix α - A plate-shaped body made of iron oxide is contained, the thickness direction of the plate-shaped body is the c-axis of α-iron oxide, and the c-axis of α-iron oxide in the plate-shaped body is the surface of the glass substrate. preferably parallel to the The composite layer is the same as the composite layer formed on the ceramic sintered body.

The method for producing the glass molded article of the present invention is not particularly limited, but molten glass is formed by heating a glass raw material containing 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ to 1100 ° C. or higher. The first step is to heat the molten glass at 1100° C. or higher in a reducing atmosphere to reduce iron ions in the molten glass, and the second step is to heat the molten glass to 800 to 1100° C. in an oxidizing atmosphere. It is preferable to obtain by a method having a third step of forming the iron oxide layer by heat treatment at .

In the first step, molten glass is formed by heating frit. The glass raw material to be supplied to the first step should contain 0.2 to 5% by mass of iron element in terms of Fe ₂ O ₃ . The iron oxide layer is formed by subjecting such a glass raw material to the first to third steps. Further, the content of aluminum element in the glass raw material is usually 0 to 25% by mass, preferably 0.1 to 25% by mass, in terms of Al ₂ O ₃ . The iron element is contained as Fe ₂ O ₃ , Fe ₃ O ₄ , FeO, Fe or the like, and the aluminum element is contained as Al ₂ O ₃ or the like in the glass raw material. Elements other than the iron element and the aluminum element to be contained in the glass raw material may be selected according to the type of the glass substrate. A suitable mixture of inorganic powders may be used as the glass raw material, or a glass containing an iron element may be used.

Molten glass is formed by heating the frit to 1100° C. or higher. As a method of heating the frit in the first step, a method of raising the temperature of the frit from room temperature to 1100° C. or higher at a rate of 0.1 to 10° C./min.

In the second step, the molten glass is heat-treated at 1100° C. or higher in a reducing atmosphere to reduce iron ions in the molten glass, particularly iron ions in the vicinity of the surface. This step can be performed in the same manner as the second step in the method for producing the ceramic sintered body described above.

In the third step, the iron oxide layer is formed by heat-treating the molten glass at 800 to 1100° C. in an oxidizing atmosphere. If the treatment temperature is less than 800° C., the oxide layer may not be sufficiently formed. The treatment temperature is preferably 900° C. or higher. On the other hand, if the treatment temperature exceeds 1100° C., the amount of α-iron oxide formed is excessively increased, and the resulting glass molded article may be reddish and have a poor appearance. The treatment temperature is preferably 1050° C. or lower. This step can be performed in the same manner as the third step in the method for producing the ceramic sintered body described above, except that the treatment temperature is different.

The glass molded article obtained in this way also has a metallic luster, particularly a golden metallic luster, so that it is excellent in design and can be easily produced. Therefore, the glass molded product can be suitably used as tableware, arts and crafts, building materials such as tiles, and the like.

EXAMPLES Hereinafter, the present invention will be described more specifically using examples.

Example 1
Iron element is 2.77% by mass in terms of _{Fe2O3 ,} silicon element is 63.5% by mass in terms of _SiO2 , aluminum element is 21.6% by mass in terms of _{Al2O3 ,} and potassium element is in terms of _K2O . After pulverizing and mixing clay containing 2.1% by mass of titanium, 0.7% by mass of titanium in terms of _TiO2 , and 0.7% by mass of magnesium in terms of MgO in a mortar, the clay is classified using a sieve. , a powder having a particle size of 100 μm or less was obtained. This was pressure-molded to obtain a disk-shaped unsintered ceramic substrate having a diameter of 20 mm and a thickness of 2 mm. A magnetic crucible was placed face down in an alumina crucible, and the substrate was placed on top of the magnetic crucible. After placing 0.03 g of potassium carbonate (K ₂ CO ₃ ) powder around the magnetic crucible, this alumina crucible was set in an electric furnace and heated to 1230°C at a rate of 2.5°C per minute in the air. (first step).

When the temperature reached 1230°C, the inside of the electric furnace was replaced with a mixed gas of argon/carbon monoxide = 90/10 (vol%), and then the mixture was kept at 1230°C for 6 hours while continuing to introduce the mixed gas. (Second step). After that, the alumina crucible was cooled to 900° C. at a rate of 1.5° C./min while continuously introducing the mixed gas. When the temperature reached 900° C., the introduction of the mixed gas was stopped, air was introduced, and the alumina crucible was held at 900° C. for 2 hours (third step). After that, the electric furnace was turned off and cooled to room temperature.

[Appearance observation]
A photograph of the appearance of the obtained ceramic sintered body is shown in FIG. 1(b). The ceramic sintered body had a golden metallic luster and an extremely good appearance.

[Electron microscope observation, elemental mapping and electron diffraction measurement]
Using an electron microscope "JEM-2800" manufactured by JEOL Ltd., the cross section of the ceramic sintered body obtained was subjected to electron microscope observation, elemental mapping and electron diffraction measurement. In the lower part of FIG. 2, an electron micrograph (g) of the cross section of the obtained ceramic sintered body and an elemental map (h: Fe, i: Al, j: Si, k: K, l: Fe+Al+Si) of the cross section are shown. . FIG. 3 shows an enlarged electron micrograph g of FIG. From the results of electron microscope observation, a glass layer 1 (thickness 5 μm) was formed on the surface of the base material, an iron oxide layer 2 (thickness 100 nm) was formed on the surface of the glass layer 1, and a composite was formed on the surface of the iron oxide layer 2. It was confirmed that the body layer 3 (thickness 100 nm) was formed. From the results of the elemental map, it was confirmed that elements such as Si, Al, and K were contained in the portion of the glass layer 1 . From this result, it is considered that the glass layer 1 is made of alkali silicate glass containing aluminum element. The electron diffraction patterns in the electron micrographs g of FIGS. 2 and 3 were obtained by electron diffraction measurement of the iron oxide layer 2 . From the electron diffraction pattern and compositional analysis results by elemental mapping, it was confirmed that the iron oxide layer 2 consisted of aluminum-substituted α-iron oxide represented by the following formula. Furthermore, from the results of electron diffraction measurement, the c-axis of the α-iron oxide in the iron oxide layer 2 is parallel to the ceramic substrate (the c-axis is perpendicular to the thickness direction of the iron oxide layer 2). was confirmed.
_{α - Fe1.87Al0.13O3}

The surface of the obtained ceramic sintered body was observed with a transmission electron microscope and electron diffraction was measured. When the surface of the ceramic sintered body was measured as it was, the presence of the glass matrix in the composite layer 3 prevented electron diffraction measurement of the plate-like body 4 and the iron oxide layer 2 in the composite layer 3. rice field. Therefore, after removing the glass matrix from the ceramic sintered body using a 47% hydrogen fluoride aqueous solution, the ceramic sintered body was placed in a sample tube containing carbon tetrachloride. After ultrasonically dispersing the crystals in carbon tetrachloride, the carbon tetrachloride was added dropwise to the microgrid. A transmission electron microscope observation and an electron diffraction measurement of the test piece including the obtained iron oxide layer 2 and composite layer 3 were performed. The results are shown in FIGS. 5(b) and 6. FIG. A plate-like body 4 was formed on the surface of the iron oxide layer 2 as shown in FIGS. 5(b) and 6 . From the results of electron diffraction measurement (electron diffraction pattern 5 in FIG. 6) and elemental mapping of the plate-like body 4, the plate-like body 4 is the same aluminum-substituted α-iron oxide that forms the iron oxide layer 2. It was confirmed that it consisted of Furthermore, from the results of electron diffraction measurement, the thickness direction of the plate-like body 4 is the c-axis of the α-iron oxide in the plate-like body 4, and the c-axis of the α-iron oxide in the plate-like body 4 is the ceramic base material. It was confirmed to be parallel to the surface.

[Color measurement]
CIE1976L ^* a ^* b ^* color space of the obtained ceramic sintered body (the portion where the iron oxide layer 2 and the composite layer 3 are formed) using a Konica Minolta spectrophotometer "CM-2600d" The lightness index L ^* , and the chromaticness indices a ^* and b ^* were measured. Based on JIS Z8722-2000, the measurement conditions were SCI (specular reflection included) method, the light source was CIE standard light source D65, the viewing angle was 10°, and the measurement range was 3 mmφ. The resulting ceramic sintered body had a lightness index L ^* of 61.4, a chromaticness index a ^* of 6.1, and a chromaticness index b ^* of 20.1.

Reference example 1
FIG. 4 shows a cross-sectional electron micrograph (a) and an elemental map (b: Fe, c: Al, d: Si, e: K, f: Fe + Al + Si) of the cross section of Kinsai Bizen ware produced by the artist. From the results of electron microscopic observation, it was confirmed that a glass layer (thickness: 2 μm) was formed on the surface of the substrate, and a composite layer (thickness: 100 nm) was formed on the surface of the glass layer. The electron diffraction pattern in the electron micrograph a of FIG. 4 was obtained by electron diffraction measurement of the composite layer. From the results of this electron diffraction measurement, the c-axis of the α-iron oxide forming the plate-like body in the composite layer is perpendicular to the ceramic substrate (the c-axis and the thickness direction of the composite layer are parallel ) was confirmed.

FIG. 5(a) shows a transmission electron microscope image and an electron diffraction pattern of a portion including the composite layer in the Kinsai Bizen ware made by the artist. From this transmission electron microscope image and the result of electron diffraction measurement of the plate (diffraction pattern in FIG. 5(a)), the thickness direction of the plate in the Bizen ware is the c-axis of α-iron oxide in the plate. It was confirmed that the c-axis of the α-iron oxide in the plate-like body was perpendicular to the surface of the ceramic substrate.

As a result of measuring the color of the gold colored part of Bizen ware produced by the artist in the same manner as in Example 1, the lightness index L ^* was 46 to 58, and the chromaticness index a ^* was 0.4 to 3.5. and the chromaticness index b ^* was 9-12.

Examples 2 and 3
A ceramic sintered body was obtained in the same manner as in Example 1 except that the treatment temperature in the third step was changed (Example 2: 950°C, Example 3: 850°C). When heat-treated at 950° C. in the third step (Example 2), the resulting ceramic sintered body had a reddish metallic luster and a good appearance. Further, the color was measured in the same manner as in Example 1. As a result, the lightness index L ^* was 59.7, the chromaticness index a ^* was 3.6, and the chromaticness index b ^* was 11.3. there were. When heat-treated at 850° C. (Example 3), the resulting ceramic sintered body had a yellow-brown metallic luster and had a good appearance. Further, the color was measured in the same manner as in Example 1. As a result, the lightness index L ^* was 54.7, the chromaticness index a ^* was 2.2, and the chromaticness index b ^* was 10.5. there were. Thus, it was confirmed that the color tone of the resulting ceramic sintered body can be controlled by adjusting the treatment temperature in the third step.

Example 4
A powder (clay) having a particle size of 100 μm or less was obtained in the same manner as in Example 1. A powder obtained by mixing 1 g of the obtained powder and 0.2 g of potassium carbonate was placed in a crucible, heated in an electric furnace at 1450° C. for 1 hour, and then cooled to obtain a pale green glass. . The resulting glass was pulverized to obtain powder. _The obtained powder was placed in a _crucible and set in an electric furnace. A molded glass article was obtained by carrying out the steps. The glass molded product had a golden metallic luster and an extremely good appearance.

Example 5
An unsintered ceramic substrate obtained in the same manner as in Example 1 was set in an electric furnace and fired in the atmosphere at 1230° C. for 1 hour. Steps 1 to 3 were performed in the same manner as in Example 1, except that the ceramic sintered body thus obtained was used instead of the unsintered ceramic base material. FIG. 7 shows photographs of the appearance of the obtained ceramic sintered body after heat treatment (steps 1 to 3) [FIG. 7(b)] and the ceramic sintered body before heat treatment [FIG. 7(a)]. The ceramic sintered body after the heat treatment [FIG. 7(b)] had a golden metallic luster and an extremely good appearance.

Comparative example 1
After cooling the alumina crucible to 900 ° C. after performing the second step, without performing the third step of holding at 900 ° C. for 2 hours, the electric furnace was turned off and cooled to room temperature. A ceramic sintered body was obtained in the same manner. A photograph of the appearance of the obtained ceramic sintered body is shown in FIG. The ceramic sintered body had luster, but did not have metallic luster. Color measurements were carried out in the same manner as in Example 1. As a result, the lightness index L ^* was 60.9, the chromaticness index a ^* was −0.7, and the chromaticness index b ^* was 1.2. rice field. Electron microscopic observation, elemental mapping, and electron diffraction measurement of the cross section of the obtained ceramic sintered body were carried out in the same manner as in Example 1. The upper part of FIG. 2 shows an electron micrograph (a) of the cross section of the obtained ceramic sintered body, and an elemental map (b: Fe, c: Al, d: Si, e: K, f: Fe + Al + Si) of the cross section. . Although a glass layer was formed on the surface of the ceramic sintered body, only a very thin layer of α-iron oxide was formed on the surface of the glass layer.

REFERENCE SIGNS LIST 1 glass layer 2 iron oxide layer 3 composite layer 4 plate 5, 6 electron diffraction pattern

Claims (11)

A ceramic sintered body in which a glass layer and an iron oxide layer are formed on the surface of a ceramic base material,
The iron oxide layer is formed on the surface of the glass layer,
The iron oxide layer has the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0.05 to 0.2. ]
Made of aluminum- substituted α-iron oxide represented by
A ceramic sintered body having metallic luster, wherein the c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the ceramic base. A ceramic sintered body in which a glass layer , an iron oxide layer and a composite layer are formed on the surface of a ceramic base material,
The iron oxide layer is formed on the surface of the glass layer, and the composite layer is formed on the surface of the iron oxide layer ,
The iron oxide layer has the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0 to 0.2. ]
Consists of α-iron oxide optionally substituted with aluminum represented by
the c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the ceramic base ;
The composite layer contains a plate-shaped body made of α-iron oxide optionally substituted with aluminum represented by the above formula (1) in a glass matrix,
The thickness direction of the plate-like body is the c-axis of the α-iron oxide, and the c-axis of the α-iron oxide in the plate-like body is parallel to the surface of the ceramic base material, and has metallic luster. Ceramic sintered body. 3. The ceramic sintered body according to claim 2 , wherein said composite layer has a thickness of 10 to 500 nm. 4. The ceramic sintered body according to claim 2 , wherein said glass layer and said glass matrix are made of alkali silicate glass. 5. The ceramic sintered body according to claim 1, wherein said glass layer has a thickness of 1 to 1000 μm and said iron oxide layer has a thickness of 10 to 500 nm. A ceramic ware comprising the ceramic sintered body according to any one of claims 1 to 5 . A building material comprising the ceramic sintered body according to any one of claims 1 to 5 . A glass layer and an iron oxide layer were formed on the surface of the ceramic substrate A method for producing a ceramic sintered body,
In a gas atmosphere containing an alkali metal element, Fe₂O.₃A first step of forming a molten glass layer containing iron ions and alkali metal ions on the surface of the ceramic substrate by heating the ceramic substrate containing 0.2 to 5% by mass in conversion to 1100 ° C. or higher;
a second step of reducing iron ions in the glass layer by heat-treating the ceramic base on which the glass layer is formed at 1100° C. or higher in a reducing atmosphere;
A third step of forming the iron oxide layer by heat-treating the ceramic base material at 800 to 1000° C. in an oxidizing atmosphere.death,
The iron oxide layer is formed on the surface of the glass layer,
The iron oxide layer has the following formula (1)
α-Fe _2-x Al _x O. ₃ (1)
[In the formula, x is 0 to 0.2. ]
Consists of α-iron oxide optionally substituted with aluminum represented by
The c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the ceramic base material, and has metallic lusterA method for producing a ceramic sintered body. A glass molded product in which an iron oxide layer is formed on the surface of a glass substrate,
The iron oxide layer has the following formula (1)
α-Fe2 _{- xAlxO3 (} 1)
[In the formula, x is 0.05 to 0.2. ]
Made of aluminum- substituted α-iron oxide represented by
A glass molded article having metallic luster, wherein the c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the glass substrate. Iron oxide layer on the surface of the glass substrateand composite layerA glass molded product in which
The composite layer is formed on the surface of the iron oxide layer,
The iron oxide layer has the following formula (1)
α-Fe_2-xAl_xO.₃ (1)
[In the formula, x is 0 to 0.2. ]
Consists of α-iron oxide optionally substituted with aluminum represented by
The c-axis of the α-iron oxide in the iron oxide layer is parallel to the surface of the glass substrate.the law of nature,
The composite layer contains a plate-shaped body made of α-iron oxide optionally substituted with aluminum represented by the above formula (1) in a glass matrix,
The thickness direction of the plate-shaped body is the c-axis of the α-iron oxide, and the c-axis of the α-iron oxide in the plate-shaped body is parallel to the surface of the glass substrate.A glass molded article having a metallic luster. An iron oxide layer was formed on the surface of the glass substrate A method for manufacturing a glass molded product,
Fe₂O.₃A first step of forming molten glass by heating a glass raw material containing 0.2 to 5% by mass in terms of conversion to 1100 ° C. or higher,
a second step of reducing iron ions in the molten glass by heat-treating the molten glass at 1100° C. or higher in a reducing atmosphere;
A third step of forming the iron oxide layer by heat-treating the molten glass at 800 to 1100° C. in an oxidizing atmosphere.death,
The iron oxide layer has the following formula (1)
α-Fe _2-x Al _x O. ₃ (1)
[In the formula, x is 0 to 0.2. ]
Consists of α-iron oxide optionally substituted with aluminum represented by
The c-axis of α-iron oxide in the iron oxide layer is parallel to the surface of the glass substrate, and has metallic lusterA method for manufacturing a glass molded article.

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