JP2010111551A - Method for manufacturing aluminum titanate-based ceramic - Google Patents

Abstract

[PROBLEMS] To produce a ceramic having a smaller thermal expansion coefficient and a shrinkage ratio when the temperature is lowered from a high temperature with respect to aluminum titanate ceramics such as aluminum titanate and aluminum magnesium titanate, which are ceramics having excellent heat resistance. To provide.
A method for producing an aluminum titanate-based ceramics comprising a step of firing a raw material mixture containing a titanium source compound, an aluminum source compound and a glass frit, wherein the glass frit contains 0.5 wt% or more of fluorine. A manufacturing method for ceramics.
[Selection figure] None

Description

  The present invention relates to a method for producing an aluminum titanate ceramic.

  Aluminum titanate ceramics include titanium and aluminum as constituent elements, and have a crystal pattern of aluminum titanate in an X-ray diffraction spectrum, and are known as ceramics having excellent heat resistance. In recent years, as a material constituting a ceramic filter for collecting fine carbon particles contained in exhaust gas discharged from internal combustion engines such as diesel engines, etc. Industrial use value is increasing.

As a method for producing such an aluminum titanate-based ceramic, a method of firing a raw material mixture containing a powder of a titanium source compound such as titania and an aluminum source compound such as alumina is known. It is also known that an aluminum titanate-based ceramic with improved heat resistance can be obtained by firing a raw material mixture to which alkali feldspar powder is added [Patent Document 1].
WO2005 / 105704 gazette

  As such aluminum titanate ceramics, in addition to heat resistance, those having a small thermal expansion coefficient and those having a small shrinkage when lowered from a high temperature of about 1000 ° C. are required.

  Therefore, the present inventors have intensively studied to develop a method capable of producing an aluminum titanate-based ceramic having a smaller coefficient of thermal expansion and a shrinkage rate when the temperature is lowered from a high temperature, and as a result, the present invention has been achieved.

  That is, the present invention is a method for producing an aluminum titanate ceramic having a step of firing a raw material mixture containing a titanium source compound, an aluminum source compound and a glass frit, wherein the glass frit contains 0.5 wt% or more of fluorine. A characteristic manufacturing method is provided.

  According to the production method of the present invention, it is possible to produce an aluminum titanate-based ceramic having a smaller coefficient of thermal expansion and a shrinkage rate when the temperature is lowered while maintaining good heat resistance than by the conventional production method.

  In the production method of the present invention, a raw material mixture containing a titanium source compound, an aluminum source compound and glass frit is used as the raw material mixture, and the glass frit containing 0.5 wt% or more of fluorine is used.

  Examples of the titanium source compound include titanium oxide powder. Examples of titanium oxide include titanium (IV) oxide, titanium (III) oxide, and titanium (II) oxide. Titanium (IV) oxide is preferably used. Examples of the crystalline form of titanium oxide (IV) include anatase type, rutile type, brookite type and the like, and it may be amorphous, more preferably anatase type and rutile type.

  Other titanium source compounds include titanium compounds that are led to titania (titanium oxide) by firing alone in air. Examples of such compounds include titanium salts, titanium alkoxides, titanium hydroxide, titanium nitride, titanium sulfide, and titanium metal.

  Specific examples of the titanium salt include titanium trichloride, titanium tetrachloride, titanium sulfide (IV), titanium sulfide (VI), titanium sulfate (IV), and the like. Specific examples of the titanium alkoxide include titanium (IV) ethoxide, titanium (IV) methoxide, titanium (IV) t-butoxide, titanium (IV) isobutoxide, titanium (IV) n-propoxide, titanium (IV) tetraiso Examples thereof include propoxides and chelating products thereof.

  In addition, a titanium source compound may contain the inevitable impurity mixed from a raw material or a manufacturing process.

  Examples of the aluminum source compound include alumina (aluminum oxide) powder. Examples of the crystal type of alumina include γ type, δ type, θ type, and α type, and may be amorphous. The aluminum source compound is preferably α-type alumina.

  Other aluminum source compounds include aluminum compounds that are led to alumina by firing alone in air. Examples of such a compound include an aluminum salt, aluminum alkoxide, aluminum hydroxide, and metal aluminum.

  The aluminum salt may be an inorganic salt with an inorganic acid or an organic salt with an organic acid. Specific examples of the aluminum inorganic salt include aluminum nitrates such as aluminum nitrate and ammonium nitrate, and aluminum carbonates such as ammonium aluminum carbonate. Examples of the aluminum organic salt include aluminum oxalate, aluminum acetate, aluminum stearate, aluminum lactate, and aluminum laurate.

  Specific examples of the aluminum alkoxide include aluminum isopropoxide, aluminum ethoxide, aluminum sec-butoxide, aluminum tert-butoxide and the like.

  Examples of the crystal type of aluminum hydroxide include a gibbsite type, a bayerite type, a norosotrandite type, a boehmite type, and a pseudoboehmite type, and may be indefinite (amorphous). Examples of the amorphous aluminum hydroxide include an aluminum hydrolyzate obtained by hydrolyzing an aqueous solution of a water-soluble aluminum compound such as an aluminum salt or an aluminum alkoxide.

  The aluminum source compound may contain unavoidable impurities derived from the raw material or mixed in the manufacturing process.

  The raw material mixture used in the method for producing an aluminum titanate-based ceramic of the present invention preferably further contains a magnesium source compound in addition to the titanium source compound and the aluminum source compound. Examples of the magnesium source compound include magnesia (magnesium oxide).

  Other magnesium source compounds also include compounds that are led to magnesia by firing alone in air. Examples of such a compound include magnesium salt, magnesium alkoxide, magnesium hydroxide, magnesium nitride, and magnesium metal.

  Specific examples of magnesium salts include magnesium chloride, magnesium perchlorate, magnesium phosphate, magnesium pyrophosphate, magnesium oxalate, magnesium nitrate, magnesium carbonate, magnesium acetate, magnesium sulfate, magnesium citrate, magnesium lactate, magnesium stearate, Examples include magnesium salicylate, magnesium myristate, magnesium gluconate, magnesium dimethacrylate, and magnesium benzoate.

  Specific examples of the magnesium alkoxide include magnesium methoxide and magnesium ethoxide.

As the magnesium source compound, a compound also serving as an aluminum source compound can be used. An example of such a compound is magnesia spinel [MgAl ₂ O ₄ ] powder.

  The magnesium source compound may contain unavoidable impurities that are derived from raw materials or mixed in during the manufacturing process.

Further, in the present invention, a compound having two or more metal elements as a component among a titanium source compound, an aluminum source compound and a magnesium source compound, such as a composite oxide such as magnesia spinel [MgAl ₂ O ₄ ], It can be considered to be the same as the raw material mixture in which the respective metal source compounds are mixed. Further, the raw material mixture may contain aluminum titanate or aluminum magnesium titanate itself. For example, when aluminum magnesium titanate is used as the raw material mixture, the titanium source compound, the aluminum source compound and the magnesium source compound were combined. Corresponds to raw material mixture.

The amount of titanium source compound and aluminum source compound used is 100 parts by mass of the total amount of titania [TiO ₂ ] converted titanium source compound and alumina [Al ₂ O ₃ ] converted aluminum source compound, The amount of titania-converted titanium source compound is usually 30 to 70 parts by weight, and the amount of alumina-converted aluminum source compound is usually 70 to 30 parts by weight, preferably of titania-converted titanium source compound. The amount used is 40 parts by mass to 60 parts by mass, and the amount of aluminum source compound converted to alumina is 60 parts by mass to 40 parts by mass.

On the other hand, when the raw material mixture further contains a magnesium source compound, the content of the magnesium source compound is the sum of the usage amount of the titanium source compound in terms of titania and the usage amount of the aluminum source compound in terms of alumina [Al ₂ O ₃ ]. The amount of magnesium source compound converted to magnesia [MgO] per 100 parts by mass is usually 0.1 part by mass to 10 parts by mass, preferably 8 parts by mass or less.

Glass frit refers to flakes or powdered glass obtained by pulverizing glass. As the glass constituting the glass frit, silicate glass containing general silicic acid [SiO ₂ ] as a main component (50% by weight or more in all components) is used. Other components include alumina [Al ₂ O ₃ ], sodium oxide [Na ₂ O], potassium oxide [K ₂ O], calcium oxide [CaO], magnesia [MgO], as in general silicate glass. May be included.

  In particular, in the production method of the present invention, a glass frit containing 0.5 wt% or more of fluorine as a glass component is used. A glass frit with a low fluorine content exhibits a high shrinkage when the temperature is lowered from a high temperature. On the other hand, the upper limit of the fluorine content as a general glass component is usually 5 wt%. If the fluorine content exceeds 5 wt%, the furnace material may be significantly corroded during firing, which is not preferable.

  The preferred addition amount of the glass frit is 0.1 to 20 parts by weight, preferably 10 parts by weight or less with respect to 100 parts by weight of the total amount of the titanium source compound and the aluminum source compound. The particle size of the glass frit used in the present invention is preferably small so that it can be uniformly distributed in the mixture, and the center particle size is usually 15 μm or less, preferably 10 μm or less.

  In the production method of the present invention, when each metal source compound that is the titanium source compound, the aluminum source compound, and the magnesium source compound is a powder, the respective metal source compound and the glass frit are mixed. Thus, a raw material mixture used in the production method of the present invention is obtained. In addition, when a non-powdered metal source compound such as a lump is included, or when it is desired to further uniformly mix, a mixture of each metal source compound and the glass frit may be ground and mixed. The mixing method may be dry mixing or wet mixing.

  In order to mix in a dry atmosphere, for example, the raw material mixture may be mixed and stirred in a pulverizing container without being dispersed in a liquid medium. Usually, stirring is performed in the pulverizing container in the presence of a pulverizing medium.

  As the pulverization container, a container made of a metal material such as stainless steel is usually used, and the inner surface may be coated with a fluorine resin, a silicon resin, a urethane resin, or the like. The internal volume of the grinding container is usually 1 to 4 times, preferably 1.2 to 3 times the volume of the total volume of the raw material mixture and grinding media.

  Examples of the grinding media include alumina balls and zirconia balls having a diameter of 1 mm to 100 mm, preferably 5 mm to 50 mm. The amount of grinding media used is usually 1 to 1000 times, preferably 5 to 100 times, the amount of the raw material mixture used.

  The pulverization is performed, for example, by pouring the raw material mixture and the pulverization medium into the pulverization container and then vibrating the pulverization container, rotating it, or both. By vibrating or rotating the grinding container, the raw material mixture is stirred and mixed with the grinding media and then ground. In order to vibrate or rotate the pulverization vessel, for example, a normal pulverizer such as a vibration mill, a ball mill, and a planetary mill can be used, and the vibration mill is preferably used because it can be easily implemented on an industrial scale. It is done. When the grinding container is vibrated, the amplitude is usually 2 mm to 20 mm, preferably 12 mm or less. The pulverization may be performed continuously or batchwise, but is preferably performed continuously because it is easy to implement on an industrial scale. The time required for pulverization is usually 1 minute to 6 hours, preferably 1.5 minutes to 2 hours.

  When the raw material mixture is pulverized dry, additives such as a pulverization aid and a peptizer may be added. Examples of the grinding aid include alcohols such as methanol and ethanolpropanol, glycols such as propylene glycol, polypropylene glycol and ethylene glycol, amines such as triethanolamine, and higher fatty acids such as palmitic acid, stearic acid and oleic acid. Carbon materials such as carbon black and graphite can be used, and these can be used alone or in combination of two or more.

  When using the additive, the total amount used is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 0.75, per 100 parts by weight of the raw material mixture. Parts by mass to 2 parts by mass.

  On the other hand, in wet mixing, for example, these raw material mixtures can be mixed and dispersed in a liquid medium. As a mixer, only a stirring process may be performed in a normal liquid solvent, or stirring may be performed in a pulverization container in the presence of pulverization media.

  As the pulverization container, a container made of a metal material such as stainless steel is usually used, and the inner surface may be coated with a fluorine resin, a silicon resin, a urethane resin, or the like. The internal volume of the grinding container is usually 1 to 4 times, preferably 1.2 to 3 times the volume of the total volume of the raw material mixture and grinding media.

  In the wet mixing, water is usually used as a solvent, and ion-exchanged water is preferable from the viewpoint of few impurities. However, organic solvents such as alcohols such as methanol, ethanol, butanol, and propanol, and glycols such as propylene glycol, polypropylene glycol, and ethylene glycol can be used as the solvent. The usage-amount of a solvent is 20 mass parts-1000 mass parts normally with respect to 100 mass parts of said mixture amounts, Preferably it is 30 mass parts-300 mass parts.

  Examples of the grinding media include alumina balls and zirconia balls having a diameter of 1 mm to 100 mm, preferably 5 mm to 50 mm. The amount of the grinding media used is usually 1 to 1000 times, preferably 5 to 100 times the mass of the raw material mixture.

  When the raw material mixture is pulverized wet, a pulverization aid may be added. For example, after the raw material mixture and pulverization media are put into the pulverization container, the pulverization container is vibrated, rotated, or It is done by both. By vibrating or rotating the grinding container, the raw material mixture is stirred and mixed with the grinding media and then ground. In order to vibrate or rotate the pulverization container, for example, a normal pulverizer such as a vibration mill, a ball mill, a planetary mill, etc. can be used, and a vibration mill is preferable because it can be easily implemented on an industrial scale. Used. When the grinding container is vibrated, the amplitude is usually 2 mm to 20 mm, preferably 12 mm or less. The pulverization may be performed continuously or batchwise, but is preferably performed continuously because it is easy to implement on an industrial scale.

  A dispersant may be added to the solvent when mixing in a wet manner. Examples of the dispersant include inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid, organic acids such as oxalic acid, citric acid, acetic acid, malic acid and lactic acid, alcohols such as methanol, ethanol and propanol, and interfaces such as ammonium polycarboxylate. An active agent etc. are mentioned. When using a dispersing agent, the usage-amount is 0.1 mass part-20 mass parts normally per 100 mass parts of solvent, Preferably it is 0.2 mass part-10 mass parts.

  After mixing, the solvent can be removed to obtain the uniformly mixed mixture. Removal of the solvent is usually performed by distilling off the solvent.

  In removing the solvent, it may be air-dried at room temperature, vacuum-dried, or heat-dried. The drying method may be stationary drying or fluidized drying. Although the temperature at the time of heat-drying is not specified in particular, it is usually from 50 ° C to 250 ° C. Examples of equipment used for heat drying include a shelf dryer, a slurry dryer, and a spray dryer.

  In addition, although it may be dissolved in a solvent depending on the type of the aluminum source compound used in the wet mixing, the aluminum source compound and the like dissolved in the solvent are precipitated again as a solid content by distilling off the solvent.

  In this way, a raw material mixture is obtained by mixing a titanium source compound, an aluminum source compound and a glass frit, preferably a magnesium source, and the raw material mixture is sintered to sinter aluminum titanate ceramics. It's something to become a body. The titanium source compound, aluminum source compound, glass frit and the like are usually contained in the raw material mixture in powder form.

  Or you may bake, after shape | molding a powdery raw material mixture and making it the molded object of a raw material mixture. The formation of aluminum titanate can be promoted by firing after forming the molded body. Examples of the molding machine used for molding include a single screw extruder, a single screw press, a tableting machine, and a granulator.

  When using a uniaxial extrusion molding machine, a pore forming agent, a binder, a lubricant, a plasticizer, a dispersing agent, a solvent, and the like can be added to the raw material mixture for molding.

Examples of the pore-forming agent include carbon materials such as graphite, resins such as polyethylene, polypropylene, and polymethyl methacrylate, plant materials such as starch, nut shells, walnut shells, and corn, ice, and dry ice.
Examples of the binder include celluloses such as methylcellulose, carboxymethylcellulose, and sodium carboxymethylcellulose; alcohols such as polyvinyl alcohol; salts such as lignin sulfonate; waxes such as paraffin wax and microcrystalline wax; EVA, polyethylene, polystyrene, liquid crystal Examples thereof include thermoplastic resins such as polymers and engineering plastics. Some substances may serve as both a pore-forming agent and a binder. As such a substance, any substance can be used as long as it can adhere particles to each other at the time of molding to retain the shape of the molded body, and can burn itself to form pores at the time of subsequent firing. In particular, polyethylene may be applicable.

  Examples of the lubricant include alcohol-based lubricants such as glycerin, higher fatty acids such as caprylic acid, lauric acid, palmitic acid, alginic acid, oleic acid and stearic acid, and metal stearates such as aluminum stearate. . Such a lubricant usually also functions as a plasticizer.

  As the solvent, alcohols such as methanol and ethanol are usually used in addition to ion-exchanged water.

  When the raw material mixture or a molded body thereof is fired to obtain a sintered body of an aluminum titanate ceramic such as aluminum titanate or aluminum magnesium titanate, the firing temperature is usually 1300 ° C. or higher, preferably 1400 ° C. or higher. . On the other hand, in order to make the sintered body of the aluminum titanate ceramic produced easy to process, or to make it easy to be pulverized afterwards, the sintering temperature is usually 1600 ° C. Hereinafter, it is preferably 1550 ° C. or lower. The rate of temperature increase up to the firing temperature is not particularly limited, but is usually 2 ° C./hour to 500 ° C./hour. Moreover, you may provide the process hold | maintained at fixed temperature in the middle of baking.

  Firing is usually carried out in the air, but depending on the components of the raw material mixture and the ratio of the amount used, it may be fired in an inert gas such as nitrogen gas or argon gas, or carbon monoxide gas, hydrogen gas, etc. You may bake in such reducing gas. Further, the firing may be performed by lowering the water vapor partial pressure in the atmosphere.

  Firing is usually performed using a conventional firing furnace such as a tubular electric furnace, a box-type electric furnace, a tunnel furnace, a far-infrared furnace, a microwave heating furnace, a shaft furnace, a reflection furnace, a rotary furnace, or a roller hearth furnace. Firing may be performed batchwise or continuously. Moreover, you may carry out by a stationary type and may carry out by a fluid type.

  The time required for firing may be sufficient time for the mixture to transition to the aluminum titanate-based ceramics, and varies depending on the amount of the mixture, type of firing furnace, firing temperature, firing atmosphere, etc. Min to 24 hours.

  Thus, a sintered body of the target aluminum titanate ceramic can be obtained as a fired product. The final product may be formed by grinding the sintered body.

  Furthermore, the ceramic powder can be obtained by crushing the massive ceramic sintered body. Crushing can be performed using a normal crusher such as hand crushing, mortar, ball mill, vibration mill, planetary mill, medium stirring mill, pin mill, jet mill, hammer mill, roll mill, and the like. The ceramic powder obtained by crushing may be classified by a usual method. Since the ceramic powder thus obtained has a generally spherical shape, the handling container or the like is not worn when the ceramic powder is handled.

  Furthermore, the ceramic powder can be granulated by a known powder molding technique.

The aluminum titanate-based ceramics obtained by the production method of the present invention includes an aluminum titanate crystal pattern in an X-ray diffraction spectrum, but may also include a crystal pattern such as silica, alumina, titania, etc. . When the aluminum titanate ceramic is aluminum magnesium titanate (Al ₂ (1-x) MgxTi (1 + x) O ₅ ), the value of x is 0.01 or more, preferably 0.01 or more and 0.00. 7 or less, more preferably 0.02 or more and 0.5 or less.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to the aspect of a following example.

In addition, the thermal decomposition rate of the aluminum titanate ceramics obtained in each Example and Comparative Example was measured as follows. Aluminum titanate-based ceramic powder is charged into an alumina crucible and held in a box-type electric furnace at 1100 ° C. for 48 hours to obtain aluminum magnesium titanate for thermal decomposition evaluation, and the obtained aluminum magnesium titanate for thermal decomposition evaluation is powdered The integrated intensity (I _T ) of the peak (corresponding to the titania-rutile phase (110) plane) appearing at the position of 2θ = 27.4 ° in the X-ray diffraction spectrum [XRD] and the position of 2θ = 33.7 ° From the integral intensity [I _AT ] of the peaks [corresponding to the aluminum titanate phase (230) plane and the aluminum magnesium titanate phase (230) plane) appearing in FIG.
Thermal decomposition rate (%) = 100−100 × I _AT / (I _AT + I _T ) (1)

In addition, the aluminum titanate (magnesium) conversion rate (hereinafter referred to as “AT conversion rate”) in the aluminum titanate-based ceramics obtained in each Example and Comparative Example is 2θ = 27.4 ° in the powder X-ray diffraction spectrum. and the integrated intensity of the peak appearing in the position [titania-rutile phase (110) corresponding to the surface] (I _T), a peak appears at a position of 2 [Theta] = 33.7 ° [aluminum titanate phase (230) plane and titanate The integrated intensity [I _AT ] of the aluminum magnesium phase (230) plane] was calculated from the formula (2).
AT conversion rate (%) = 100 × I _AT / (I _AT + I _T ) (2)

  Moreover, the particle shape of the powder of the aluminum titanate ceramics obtained in each Example and Comparative Example was observed with a scanning electron microscope [SEM].

Moreover, the sintered compact density of the aluminum titanate ceramics obtained in each Example and Comparative Example was measured and evaluated by the following method. First, each metal source compound described in each example and comparative example is mixed or pulverized and mixed, and 3 g of the obtained raw material mixture is molded under a pressure of 0.3 t / cm ² by a uniaxial press to form a molded body having a diameter of 20 mm. Was made. Next, this compact was fired in a box-type electric furnace at a heating rate of 300 ° C./h for 4 hours at 1450 ° C. to obtain an aluminum titanate ceramic sintered body. By measuring this sintered body by the Archimedes method, the sintered body density of the measured aluminum titanate-based ceramics was obtained.

Moreover, the measurement of the thermal expansion coefficient and shrinkage | contraction rate of the aluminum titanate ceramic sintered body obtained by each Example and a comparative example was performed by the following operation. Samples cut out from the sintered bodies of Examples and Comparative Examples obtained by measuring the sintered body density were heated to 600 ° C. at 200 ° C./h and heat-treated, and then a thermomechanical analyzer [TMA (TII Technology Co., Ltd. TMA6300) was used to measure the coefficient of thermal expansion [K ⁻¹ ] when the temperature was increased from room temperature to 1000 ° C. at 600 ° C./h. The lowest value of the shrinkage rate when the temperature was lowered at ° C./h was taken as the shrinkage rate.

[Example 1]
Titania powder [DuPont Co., Ltd., “R-900”] 20.0 g, α alumina powder [primary particle size 4 μm, secondary particle size 80 μm] 27.4 g, magnesia powder [Ube Material Co., Ltd., “UC-95M” ] 0.8 g and glass frit (manufactured by Takara Standard Co., Ltd., model number “CF0043”, fluorine content 1.2 wt%) 1.8 g together with 5 kg of alumina beads (diameter 15 mm) [aluminum volume 3 .3L]. The x value of aluminum magnesium titanate in this aluminum titanate ceramic is about 0.09.

The total volume of the mixture of these titania powder, α-alumina powder, magnesia powder and glass frit was about 50 cm ³ . Thereafter, the mixture in the pulverization container is pulverized by vibrating the container for 6 minutes under a condition corresponding to a gravitational acceleration of 10 G at a vibration mill with an amplitude of 5.4 mm, a frequency of 1760 times / minute, and a power of 5.4 kW, A raw material mixture was obtained. 5 g of this raw material mixture was placed in an alumina crucible, heated in the atmosphere to 1450 ° C. at a temperature increase rate of 300 ° C./hour with a box-type electric furnace, and fired by maintaining the same temperature for 4 hours. Thereafter, it was allowed to cool to room temperature to obtain an aluminum titanate ceramic. The obtained aluminum titanate ceramics were pulverized in a mortar to obtain aluminum titanate ceramic powders. When an X-ray diffraction spectrum of the powder was obtained by a powder X-ray diffraction method, a crystal peak of aluminum titanate was shown, and a crystal peak of α-alumina was slightly observed. No crystal peak of the titania alkyl phase was observed. The AT conversion rate of this powder was determined to be 100%. Moreover, it was 14.9% when the thermal decomposition rate of the obtained aluminum titanate ceramic was measured. Further, when the shape of the powder was observed with an SEM, most of the particles constituting the powder were almost spherical. Further, the sintered body density was measured to be 3.3 g / cm ³ , the thermal expansion coefficient was 0.8 × 10 ⁻⁶ K ⁻¹ , and the shrinkage rate was −0.14%.

[Comparative Example 1]
The same operation as in Example 1 was carried out except that the raw material glass frit used in Example 1 was changed to a glass frit (manufactured by Takara Standard Co., Ltd., model number “CK0832”, fluorine content 0.1 wt%). An aluminum ceramic powder was obtained. The AT conversion rate of this aluminum titanate ceramic was determined and found to be 100%. Further, the thermal decomposition rate of the obtained aluminum titanate ceramic was measured and found to be 23.2%. Further, when the shape of the aluminum titanate ceramic powder was observed with an SEM, most of the particles constituting the powder were substantially spherical. Further, the density of the sintered body was measured and found to be 3.37 g / cm ³ , the thermal expansion coefficient was 1.6 × 10 ⁻⁶ K ⁻¹ , and the shrinkage rate was −0.32%.

[Comparative Example 2]
The glass frit used in Example 1 was operated in the same manner as in Example 1 except that the glass frit of the model number “CF0043” was subjected to fluorine reduction treatment and changed to a glass frit having a fluorine content of 0 wt%. An aluminum titanate ceramic powder was obtained. The AT conversion rate of this aluminum titanate ceramic was determined and found to be 100%. Moreover, when the thermal decomposition rate of the obtained aluminum titanate ceramic was measured, it was 100%. Further, when the shape of the powder of this aluminum titanate ceramic was observed with an SEM, most of the particles constituting the powder were almost spherical. Further, the sintered body density was measured to be 3.35 g / cm ³ , the thermal expansion coefficient was 0.8 × 10 ⁻⁶ K ⁻¹ , and the shrinkage rate was −0.26%.

  In addition, the component and ratio of the glass frit used in Example 1 and Comparative Example 1 were confirmed with a fluorescent X-ray analyzer [Rigaku ZSX Primus II]. The results are shown in Table 1.

Aluminum titanate-based ceramics such as aluminum titanate or aluminum magnesium titanate obtained by the production method of the present invention can be used in various industrial applications, for example, firing furnaces such as crucibles, setters, pots, and furnace materials. Jigs, filters used for exhaust gas purification of internal combustion engines such as diesel engines, gasoline engines, filters for filtering food such as beer, gas components generated during petroleum refining, carbon monoxide, carbon dioxide, nitrogen, oxygen Examples thereof include ceramic filters used for a selective transmission filter for selectively transmitting light, etc., electronic parts such as a substrate and a capacitor.

Claims (3)

  A method for producing an aluminum titanate-based ceramics comprising a step of firing a raw material mixture containing a titanium source compound, an aluminum source compound and a glass frit, wherein the glass frit contains 0.5 wt% or more of fluorine. .   The method for producing an aluminum titanate-based ceramics according to claim 1, wherein the raw material mixture further contains a magnesium source compound. An aluminum titanate-based ceramic powder is obtained by the method according to claim 1 or 2, and the obtained aluminum titanate-based ceramic is crushed.