CN107635944B - Merle ceramic, kiln furniture using the same, and method for producing the same - Google Patents
Merle ceramic, kiln furniture using the same, and method for producing the same Download PDFInfo
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 58
- 238000010304 firing Methods 0.000 claims description 38
- 238000012360 testing method Methods 0.000 claims description 36
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 29
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 25
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 4
- 238000000034 method Methods 0.000 description 25
- 239000002994 raw material Substances 0.000 description 15
- 229910014779 CaAl4 Inorganic materials 0.000 description 13
- 230000005484 gravity Effects 0.000 description 12
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- 238000004901 spalling Methods 0.000 description 10
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- 239000000463 material Substances 0.000 description 5
- 238000000634 powder X-ray diffraction Methods 0.000 description 5
- -1 Calcium aluminate Chemical class 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 4
- 229910001570 bauxite Inorganic materials 0.000 description 4
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 4
- 229910021540 colemanite Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 235000014113 dietary fatty acids Nutrition 0.000 description 4
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- 238000002844 melting Methods 0.000 description 4
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- 238000004381 surface treatment Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- XUCJHNOBJLKZNU-UHFFFAOYSA-M dilithium;hydroxide Chemical compound [Li+].[Li+].[OH-] XUCJHNOBJLKZNU-UHFFFAOYSA-M 0.000 description 2
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- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 239000006028 limestone Substances 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
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- 238000007088 Archimedes method Methods 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
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- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
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- 229910052749 magnesium Inorganic materials 0.000 description 1
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- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
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- 229910052725 zinc Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/44—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Glass Compositions (AREA)
Abstract
The meteorite ceramic of the invention is derived from CaAl in X-ray diffraction2O4I.e., the integrated intensity I of the peak at 30.07 degrees 2 θ, which is the main peak of (a)BAnd from CaAl in X-ray diffraction4O7I.e., the integrated intensity I of the peak at 25.47 degrees 2 θ, which is the main peak of (a)ARatio of (I)B/IAHas a value of 0.05 or less and a coefficient of thermal expansion of 2.0X 10 measured under an atmospheric atmosphere at 27 ℃ to 300 DEG C‑6and/K is less than or equal to. The merle ceramic of the present invention is preferably one in which a reduced-size temperature region is observed in the resulting size-temperature graph or a plateau temperature region with substantially no change in size is observed in thermomechanical analysis when heated under an atmospheric atmosphere.
Description
Technical Field
The present invention relates to a merle ceramic (guest ceramics), a kiln furniture using the merle ceramic, and a method for producing the merle ceramic.
Background
In recent years, electronic components such as capacitors have been miniaturized. In the electronic component firing step, a process of putting the electronic component to be fired into a very high temperature furnace from a normal temperature for a short time together with a kiln tool for firing and taking out the electronic component from the furnace to complete firing is mainstream. Accordingly, the kiln furniture for firing is required to be free from deflection and cracking of the placing section of the material to be fired due to thermal shock even when exposed to thermal shock more severe than before, and further, to be free from peeling on the surface of the placing section.
In addition, Merle refers to a compound composed of oxides of Ca and Al, with the chemical formula generally consisting of CaAl4O7Also sometimes expressed as CaO 2Al2O3Or CA2. For example, non-patent document 1 discloses that the thermal expansion coefficient α is 3.9 × 10 when heated from 20 ℃ to 800 ℃-6Substance of/K (Table 3) as containing aluminum meteoriteCeramics of calcareous stone. Further, patent document 1 describes a ceramic product made of a ceramic material containing CaAl4O7Main phase and CaAl2O4Calcium aluminate of the minor phase and exhibits less than about 25 x 10 throughout the temperature range of about 27 c to about 800 c-7Thermal expansion at/° c. Patent document 2 describes addition of ZrO2、K2O、Li2O、B2O3、CaF2、MgO、TiO2、ZnO、SnO、SrO、Y2O3、Fe2O3Additives for low melting point, such as BaO, to reduce the thermal expansion of the ceramic containing the merle.
Documents of the prior art
Patent document
Patent document 1: US2003/232713A1
Patent document 2: US6689707B1
Non-patent document
Non-patent document 1: s. Jonas et al, Ceramics Internanonal 24(1998)211-
Disclosure of Invention
Problems to be solved by the invention
The ceramics containing merle described in non-patent document 1 (hereinafter also referred to as "merle ceramics") have a high coefficient of thermal expansion and insufficient spalling resistance. In addition, the alloy disclosed in patent document 1 is made of a material containing CaAl4O7Main phase and CaAl2O4CaAl for Merle ceramic composed of subphase calcium aluminate2O4Ratio CaAl4O7And is less stable and less resistant to deflection by high temperatures, and thus is difficult to reuse at high temperatures. In addition, as described in patent document 2, in the case of the merle ceramic in which the thermal expansion coefficient is reduced by the additive forming the low melting point composition, there is a fear that the creep property at high temperature is reduced, and the deflection becomes easy, or the high temperature strength is reduced by softening, and therefore, it is not suitable for practical use as a material for kiln furniture for firing electronic components.
Accordingly, an object of the present invention is to: provided are a merle ceramic which can eliminate various disadvantages of the prior art, a kiln furniture using the merle ceramic, and a method for producing the merle ceramic.
Means for solving the problems
The invention provides a meteorite ceramic which is derived from CaAl in X-ray diffraction2O4I.e., the integrated intensity I of the peak at 30.07 degrees 2 θ, which is the main peak of (a)BAnd from CaAl in X-ray diffraction4O7I.e., the integrated intensity I of the peak at 25.47 degrees 2 θ, which is the main peak of (a)ARatio of (I)B/IAHas a value of 0.05 or less and a coefficient of thermal expansion of 2.0X 10 measured under an atmospheric atmosphere at 27 ℃ to 300 DEG C-6and/K is less than or equal to.
Further, the present invention provides a kiln furniture using the above-described merle-aluminite ceramic.
Further, the present invention provides a method for producing the above-described merle ceramic, which is a preferable method for producing the merle ceramic, comprising the steps of: volume cumulative particle diameter D at 50 vol% cumulative volume in the laser diffraction scattering particle size distribution measurement method50Alumina particles of 5 μm or less and the volume cumulative particle diameter D50Molding a mixed powder of calcium carbonate particles having a particle size of 25 μm or less, and firing the molded article at a temperature of 1450 ℃ or higher.
Effects of the invention
The meteorite ceramic of the invention has low thermal expansion degree at high temperature and high spalling resistance. The meteorite ceramic of the present invention can be repeatedly subjected to a thermal cycle under severe heating and cooling conditions, and can be used for a long time in a firing process of electronic parts. Therefore, according to the kiln furniture of the present invention using the merle ceramic of the present invention, the running cost can be reduced and the yield of electronic components can be improved. In addition, the method for producing a merle ceramic of the present invention can efficiently produce the merle ceramic.
Drawings
FIG. 1 is an X-ray diffraction pattern of the Merle ceramic obtained in example 1.
FIG. 2 is a size-temperature plot from thermomechanical analysis of the Merle ceramic obtained in example 1.
FIG. 3 is a photomicrograph of a cross-section of the Merle ceramic from example 1, which is a photograph used to determine the number and length of microcracks.
FIG. 4 is a photomicrograph of a cross-section of the Merle ceramic obtained in example 1, which is a photograph for measuring the crystal grain size.
FIG. 5 is a graph of size versus temperature obtained by thermomechanical analysis of the Merle ceramic from example 3.
Fig. 6 is a schematic diagram illustrating a method of measuring the spall resistance.
Detailed Description
The present invention will be described below based on preferred embodiments. The calcium aluminate in the merle-aluminite ceramic of the invention is actually CaAl4O7A single phase. CaAl4O7Ratio CaAl2O4More stable, has strong resistance to high-temperature flexibility, and can be repeatedly used at high temperature. By using such a catalyst consisting essentially of CaAl4O7Calcium aluminate of single phase composition with CaAl content2O4Compared with the case of the minor phase, the merle ceramic of the present invention can be suitably used for applications such as kiln furniture which is repeatedly used at high temperatures. In addition, when CaAl having high solubility in water is not used2O4The merlinite ceramics of the present invention can also be readily processed in a variety of other applications.
The meteorite ceramic of the invention is derived from CaAl in X-ray diffraction2O4I.e., the integrated intensity I of the peak at 30.07 degrees 2 θ, which is the main peak of (a)BAnd is derived from CaAl4O7I.e., the integrated intensity I of the peak at 25.47 degrees 2 θ, which is the main peak of (a)ARatio of (I)B/IAThe value of (A) is 0.05 or less. Thus, it was judged that the Merle ceramic of the present invention does not substantially contain CaAl2O4. Powder X-ray diffraction measurement is generally performed as X-ray diffraction. Merle of Merle ceramic of the inventionB/IAThe smaller the value of (b) is, the better, the more preferably 0.01 or less, the more preferably 0.005 or less, and the most preferably 0.001 or less. From the viewpoint of easy quality control, I is defined asB/IAThe lower limit of (2) is preferably set to 0.0004 or more.
Is as followsB/IAThe value of (d) is not more than the above upper limit, and can be obtained by adjusting the ratio of alumina particles to calcium carbonate particles, adjusting the firing conditions of the mixed powder, and the like in the method for producing a merle ceramic described later.
In addition, when the powder X-ray diffraction measurement with the radiation source set to Cu radiation is performed on the merle ceramic of the present invention, it is generally preferable that the peak having the maximum intensity in the range of 10 degrees to 70 degrees 2 θ be derived from CaAl4O7The main peak of (2 θ) is 25.47 degrees.
One of the features of the merle-aluminite ceramic of the invention is also: the degree of thermal expansion is low when the glass is heated from room temperature to a specific lower temperature. The present inventors have conducted extensive studies on calcium aluminate from CaAl4O7The relationship between single phase constituent of the Merle ceramic and thermal expansion at high temperatures (e.g., above 800 ℃) has been investigated. As a result, it was found that a low degree of thermal expansion to a lower temperature is important for reducing the degree of thermal expansion at a high temperature.
Specifically, the Merle ceramic of the present invention has a coefficient of thermal expansion of 2.0X 10 from 27 ℃ to 300 ℃ measured in an atmospheric atmosphere-6and/K is less than or equal to. Thus, the merle-bauxite ceramic of the present invention can reduce the coefficient of thermal expansion at high temperatures and has high spalling resistance. From this viewpoint, the coefficient of thermal expansion of the merle-aluminite ceramic, measured in an atmospheric atmosphere, from 27 ℃ to 300 ℃ is preferably 1.5X 10-6A value of 1.0X 10 or less, more preferably 1.K-6A value of 0.5X 10 or less, particularly preferably-6and/K is less than or equal to.
From the viewpoint of breaking strength, the lower limit of the thermal expansion coefficient is preferably set to-10.0X 10-6More than K. The coefficient of thermal expansion is a linear coefficient of thermal expansion, and can be measured by the method described in the examples described later.
As described above, the size-temperature graph obtained by thermomechanical analysis (TMA) of the present invention has a specific shape, correlating with the low coefficient of thermal expansion to 300 ℃ of the present invention's Metallite ceramic. Specifically, in the case of the merle ceramic of the present invention, in the thermomechanical analysis when heating is performed under an atmospheric atmosphere, a temperature region in which a size reduction is observed or a smooth temperature region in which a size is not substantially changed is observed in the shape of the obtained size-temperature graph. This can more reliably reduce the thermal expansion coefficient of the merle ceramic at high temperatures, and improve the spallation resistance. For such a temperature region, it is more preferable to observe the Merle ceramic in the thermomechanical analysis when heated from 27 ℃ to 600 ℃ in the atmospheric atmosphere, and it is particularly preferable to observe the Merle ceramic in the thermomechanical analysis when heated from 27 ℃ to 300 ℃.
When described in detail, in the size-temperature graph, the temperature region of size reduction means a region in which the slope of the graph is reduced in size with respect to the size before the test, and the stable temperature region in which the size is not substantially changed means a region in which the size variation due to the temperature variation is small with respect to the size before the test. Specifically, the dimension-temperature graph is, for example, a graph having the temperature T as the abscissa and the ordinate, which is the ratio (Δ L/L; unit:%) of the dimension difference Δ L (═ L-L ') between the dimension L before the test and the dimension L' at a certain temperature, to the dimension L before the test. For example, the temperature region of size reduction refers to a region in which size reduction of more than 0.05% with respect to the size L before the test is observed. The temperature region in which the dimension is substantially unchanged and is stable is a region in which the thermal expansion amount (absolute amount | Δ L |) is 0.05% or less (preferably 0.01% or less) with respect to the dimension L before the test.
For example, in a graph having Δ L/L as a vertical axis and a temperature T as a horizontal axis, the lowest temperature T in one "temperature region with reduced sizeLAnd maximum temperature THDifference between (T)H-TL) Preferably 100 ℃ or higher, more preferably 150 ℃ or higher. Easy entry chirality from Merle ceramicConsidered from the viewpoint of the temperature difference (T)H-TL) The upper limit of (B) is 500 ℃ or lower.
From the viewpoint of further reducing the thermal expansion coefficient, the lowest temperature T 'in one "stable temperature region having substantially no variation in size'LAnd highest temperature T'HOf (T'H-T’L) Preferably 100 ℃ or higher, more preferably 150 ℃ or higher. The temperature difference (T ') is determined from the viewpoint of easy chirality incorporation of the Merle ceramic'H-T’L) The upper limit of (B) is 500 ℃ or lower.
In particular, the size-temperature profile obtained in thermomechanical analysis of the merle ceramic of the present invention, preferably heated from 27 ℃ to 600 ℃ in an atmospheric atmosphere, is a curve that is convex toward a decrease in size or a curve that has a smooth temperature region with substantially no change in size and a temperature region with an increase in size contiguous therewith. This can more reliably reduce the thermal expansion coefficient of the merle-bauxite ceramic at high temperatures, and can improve the spallation resistance.
As described above, in the thermomechanical analysis when heated from 27 ℃ to 600 ℃, the size-temperature graph of the present invention is a curve convex toward the direction of size reduction, or has a smooth temperature region with virtually no change in size and a temperature region with an increasing size contiguous thereto. In the former case, the size-temperature graph is observed after a size reduction greater than 0.05% relative to the pre-trial size L is observed, resulting in a size increase less than 0.05% relative to the pre-trial size L. In the former case, the temperature at which the size is most reduced in the range of 27 to 600 ℃ is also referred to as the inflection point. The reduction in size at the inflection point is preferably 0.06% or more with respect to the pre-test size L from the viewpoint of improving the effect of the present invention, and is preferably 1% or less from the viewpoint of ease of manufacturability of the merle-aluminite ceramic. The inflection point is preferably observed in the range of 100 to 600 ℃, more preferably 150 to 500 ℃.
In the latter case, a region having a thermal expansion amount (absolute amount of elongation or contraction | Δ L |) of 0.05% or less (preferably 0.01% or less) with respect to the dimension L before the test and a region having a size increase of more than 0.05% with respect to the dimension L before the test in this higher temperature region are present. The temperature at which the thermal expansion amount is shifted from a region having a thermal expansion amount of 0.05% or less to a region having a thermal expansion amount of more than 0.05% is preferably 250 to 600 ℃, and more preferably 300 to 450 ℃.
Although the reason why the size-temperature graph has a specific shape in the thermomechanical analysis is not clear, the inventors of the present invention speculate that one reason for this is that the merle ceramic of the present invention has microcracks as described below. That is, it is considered that the merle ceramic of the present invention has microcracks, and when the merle ceramic is heated, the microcracks absorb and embed expansion due to heating, thereby absorbing apparent thermal expansion. Patent document 1 describes "a network structure of microcracks", but does not describe nor teach that calcium aluminate is substantially composed of CaAl4O7Single phase formed merle ceramics have microcracks.
In order to obtain a Merle ceramic having a specific shape in the size-temperature graph in the thermomechanical analysis as described above and a Merle ceramic having a thermal expansion coefficient in a desired range from 27 ℃ to 300 ℃, the Merle ceramic of the present invention is produced by the production method described later.
Furthermore, in the case of the merle ceramic of the present invention, hysteresis (hystersis) is preferably observed in the resulting size-temperature graph in thermomechanical analysis when heated from 27 ℃ to 800 ℃ in the atmospheric atmosphere and then cooled in this temperature range. The hysteresis means that the TMA curve at warming does not coincide with the TMA curve at cooling. The inventors of the present invention have found that: thus, the thermal expansion of the merle ceramic of the present invention observed in the size-temperature graph of hysteresis is more likely to decrease upon heating at high temperatures and the spallation resistance is improved. That is, the merlinite ceramic of the present invention is preferably observed to differ in size at the same temperature upon heating and upon subsequent cooling in the thermomechanical analysis described above.
The reason for this observation of hysteresis is not clear, but the inventors of the present invention considered that it may be related to the characteristics of microcracks in the merle ceramic of the present invention. That is, it is assumed that the microcracks closed by heating are not opened during cooling, or the temperature at which the microcracks are closed during heating and the temperature at which the microcracks are opened during cooling may be different. In order to make the merle ceramic of the present invention the one in which hysteresis is observed as described above, the merle ceramic of the present invention may be produced by a production method described below, and the type of raw material, firing temperature, and the like may be adjusted.
From the viewpoint of further reducing the thermal expansion coefficient of the merle ceramic of the present invention when heated to a high temperature, the maximum value of the difference between the dimension at the time of temperature rise and the dimension at the time of cooling due to the hysteresis is preferably 0.02% or more, more preferably 0.025% or more, and particularly preferably 0.03% or more, with respect to the dimension before the test. The size difference here is the absolute value of the size difference. From the viewpoint of preventing dimensional change when the meteorite ceramic of the present invention is repeatedly heated, the maximum value is preferably 0.1% or less, more preferably 0.08% or less, and particularly preferably 0.06% or less, with respect to the size before the test.
Furthermore, from the viewpoint of more effectively reducing the thermal expansion coefficient of the monelite ceramic when heated to a high temperature, the difference in size (absolute value) between the heating and cooling in the thermomechanical analysis described above is preferably 60% or more, more preferably 80% or more, of the range from 27 ℃ to 800 ℃ in a temperature range in which the size before the test is 0.01% or more. In the case where there are a plurality of temperature regions in the range from 27 ℃ to 800 ℃ in which the difference in size between the heating and the cooling is 0.01% or more with respect to the size before the test, the ratio of the temperature range referred to herein is the sum of the respective ratios of the plurality of temperature regions.
The extent of thermal expansion of the merle aluminite ceramic of the present invention at high temperatures is very low. Specifically, the Merle ceramic preferably has a coefficient of thermal expansion of 3.4X 10 measured at 27 ℃ to 800 ℃ in an atmospheric atmosphere-6and/K is less than or equal to. Thus, the present inventionThe Merle ceramic is a Merle ceramic having high spalling resistance suitable for a kiln furniture for rapid firing of electronic parts. From this viewpoint, the coefficient of thermal expansion of the merle-aluminite ceramic, measured in an atmospheric atmosphere, from 27 ℃ to 800 ℃ is preferably 3.0X 10-6A value of not more than K, more preferably 2.5X 10-6A value of less than or equal to K, particularly preferably 2.0X 10-6and/K is less than or equal to. From the viewpoint of breaking strength, the lower limit of the thermal expansion coefficient is preferably set to-2.0X 10-6More than K. In order to obtain a merle ceramic having a thermal expansion coefficient in the thermomechanical analysis in the desired range to 800 ℃, as described above, the merle ceramic of the present invention may be produced by the production method described later.
As described above, from the viewpoint of more reliably reducing the degree of thermal expansion, the merle ceramic of the present invention is preferably observed as microcracks in a microscopic image with a cross section enlarged by 150 times. The microcracks are generally shaped to have a width direction and a length direction longer than the width direction. From the viewpoint of reducing the degree of thermal expansion, the micro-cracks having a length of 50 μm or more in the longitudinal direction in a microscopic image having a cross section enlarged by 150 times are preferably observed at least one, more preferably three, and particularly preferably ten or more at the magnification in each 0.84mm × 0.59mm field of view. For microscopic observation, a Scanning Electron Microscope (SEM) can be used as a microscope, and the method of example described later can be used, for example. Microcracks were observed in the section of the merlinite ceramic as white elongated images using a Scanning Electron Microscope (SEM) under the condition that the acceleration voltage was set at 15 kV. The number of the above-mentioned microcracks in the present monellite ceramic can be represented, for example, by the average of ten different fields of view in a microscopic image. The observation of microcracks of more than a specified length in more than one Merle ceramic in each field of view means that: it suffices that one or more of the microcracks are observed in each field of view in the case where ten different fields of view are observed under the above-described observation conditions.
The shape of the microcracks may be linear, such as curved, linear, or virtual, or may be stripe-like, and may have or may not have a bent portion, and may be continuous as in a network or may be discontinuous. In the case where the microcracks are not straight, for example, when the microcracks have a bend, the length in the longitudinal direction is the length of a path from the end of the microcrack to the end along the bend.
From the viewpoint of further reducing the degree of thermal expansion of the merle ceramic of the present invention, the total length of the microcracks having a length of 50 μm or more in the longitudinal direction in the microscope image in each field of view is preferably 500 μm or more, more preferably 1000 μm or more, and still more preferably 1500 μm or more. The total length here means the sum of the lengths in the length direction of the microcracks observed in each of the above-described fields of view. The total length in each of the above-described visual fields is preferably 7000 μm or less, more preferably 5000 μm or less, and particularly preferably 4500 μm or less, from the viewpoint of breaking strength. The total length of the above-described microcracks in the present monellite ceramic can be represented, for example, by the average of ten different fields of view in the microscope image. As described above, in the case of the Merle ceramic of the present invention, when ten different visual fields are observed, it is preferable that one or more microcracks having a length of 50 μm or more in the longitudinal direction are observed in each visual field.
Furthermore, from the viewpoint of forming a merle ceramic suitable for thermal expansion and spallation resistance of a structure in which microcracks are sought, it is preferable that the average crystal grain size observed in a microscopic image in which the cross section is enlarged from 150 times to 1500 times so that the grain boundary can be reliably recognized according to the crystal grain size is 5 μm or more. With respect to the crystal grain size, the cross section of the merle ceramic obtained as described below was ground, then subjected to atmospheric firing at 1400 ℃ (holding time of 0 minute), and subjected to thermal etching. Next, the etched surface was photographed with a Scanning Electron Microscope (SEM) under the condition that the acceleration voltage was set to 15kV to obtain an image. The code length (code length) of the obtained image was measured by the intercept method, and the crystal particle diameter was calculated. In general, the crystal grains in the image are regions surrounded by dark grain boundaries that look like a network (see fig. 4). Ten lines were measured in one field, the measurement was performed in any ten different fields, and the average of all crystal grain sizes observed in each field was used. From the above viewpoint, the average crystal particle diameter obtained by the above method is preferably 5 μm or more, and particularly preferably 10 μm or more. From the viewpoint of ease of production of the merle ceramic and breaking strength, the crystal grain size is preferably 300 μm or less on the average.
In order to set the number, length, and crystal grain size of microcracks in the present invention to the above ranges, the present invention may be produced by the production method described below, and the grain size of the raw material, firing temperature, and the like may be adjusted.
Furthermore, the merle/canate ceramic of the present invention preferably has a spallation resistance Δ T of 600 ℃ or higher. The peel resistance can be measured, for example, by the method described in the following examples. The merle ceramic having the spalling resistance of not less than the lower limit can be obtained by the production method described later. From the viewpoint of facilitating repeated use of the merle ceramic of the present invention at high temperatures, the spallation resistance Δ T is preferably 600 ℃ or higher, more preferably 700 ℃ or higher, and particularly preferably 800 ℃ or higher. In order to form a colemanite ceramic having the spallation resistance Δ T within the above range, the colemanite ceramic of the present invention may be produced by the production method described later, and the particle size of the raw material, the production method of the raw material, the kind of the raw material, and the firing temperature may be adjusted.
The merle ceramic of the present invention may contain other than CaAl within a range not impairing the effects of the present invention4O7Other compounds than the above. For example, the Merle ceramic of the present invention may contain a catalyst for reducing CaAl4O7A compound having a melting point of (3) to reduce thermal expansion, which may contain ZrO described in patent document 22、K2O、Li2O、B2O3、CaF2、MgO、TiO2、ZnO、SnO、SrO、Y2O3、Fe2O3And BaO and the like. However, for ease of prevention to function as an electronSince high-temperature characteristics such as high-temperature creep characteristics at the time of firing a kiln furniture for parts are reduced, it is preferable that the merle ceramic of the present invention contains no such compounds as much as possible.
From this viewpoint, the content of elements other than Ca, O, and Al in the colemanite ceramic of the present invention is specifically the content of Zr, K, Li, B, F, Mg, Ti, Zn, Sn, Sr, Y, Fe, Ba, Si, Ni, and Na in the whole of the colemanite ceramic is preferably 10000ppm or less, more preferably 7000ppm or less, and particularly preferably 5000ppm or less. From the viewpoint of the preferable manufacturability of the monellite ceramic, the upper limit of the total is preferably 1000ppm or more.
The merle ceramic of the present invention preferably has a bulk specific gravity of 1.8 or more, more preferably 2.0 or more. When the bulk specific gravity is equal to or higher than the lower limit value, there is an advantage that strength can be secured. The merle ceramic preferably has a bulk specific gravity of 2.88 or less, more preferably 2.85 or less. When the bulk specific gravity is not more than the upper limit, there is an advantage that weight reduction is possible. The merle ceramic of the present invention preferably has an apparent porosity (hereinafter also simply referred to as "porosity") of 0% or more, more preferably 1% or more. By setting the porosity to the lower limit or more, there is an advantage that the weight can be reduced. The porosity is preferably 37% or less, more preferably 31% or less. When the porosity is not more than the above upper limit, there is an advantage that strength can be secured. The bulk specific gravity can be calculated, for example, by measuring the mass of the Merle ceramic (or kiln furniture) and dividing it by the volume obtained from the sizing of the Merle ceramic (or kiln furniture). The porosity can be calculated by the calculation formula of (1-bulk specific gravity/apparent specific gravity) × 100. Here, the apparent specific gravity is a value obtained by dividing the mass of the merle ceramics (or kiln furniture) by the mass of water at 4 ℃ having the same volume as the apparent volume (JIS R2001), and is measured by the Archimedes method. The volume specific gravity and porosity can be adjusted by adjusting the particle size of the raw material, the method of producing the raw material, the kind of the raw material, and the firing temperature in the method for producing a merle ceramic of the present invention, and can be adjusted as a method for forming a molded article to be fired by an appropriate method corresponding to the required volume specific gravity and porosity, such as hydraulic molding and cast molding.
The merle-aluminite ceramic of the present invention preferably has a flexural strength of 8MPa or more, more preferably 10MPa or more. When the bending strength is not less than the lower limit, there is an advantage that the material has sufficient strength for handling as a firing tool. The Merle ceramic preferably has a flexural strength of 200MPa or less, more preferably 150MPa or less. When the bending strength is not more than the upper limit value, microcracks are substantially introduced, and there is an advantage that a reduction in the thermal expansion coefficient can be expected. The bending strength referred to herein is an ordinary-temperature bending strength measured in accordance with JIS R2619. The bending strength in this range can be adjusted by adjusting the particle size of the raw material, the method for producing the raw material, the type of the raw material, and the firing temperature in the method for producing a perovskite ceramic of the present invention, and in addition, can be adjusted by using an appropriate method as a method for molding a molded article to be fired.
Hereinafter, a preferred method for producing the merle ceramic of the present invention will be described. The manufacturing method comprises the following steps: a volume cumulative particle diameter D at 50 vol% of a cumulative volume measured by a laser diffraction scattering particle size distribution measurement method at a temperature of 1450 ℃ or higher50Alumina particles of 5 μm or less and the volume cumulative particle diameter D50A mixed powder of calcium carbonate particles having a particle size of 25 μm or less is fired.
In the present production method, the particle diameters of the alumina particles and the calcium carbonate particles are important. In the present production method, when the alumina particles or the calcium carbonate particles do not satisfy the above particle size, it is difficult to generate the required number of microcracks in order to sufficiently reduce the degree of thermal expansion. The volume cumulative particle diameter D of the alumina particles is considered to sufficiently reduce the degree of thermal expansion50Preferably 5 μm or less, more preferably 4 μm or less, and still more preferably 3 μm or less. In addition, the volume cumulative particle diameter D of the alumina particles is considered from the viewpoint of easy chirality introduction of the alumina particles and homogeneity of mixing by aggregation50The lower limit of (B) is preferably set to 0.01 μm or more, for example.
Volume cumulative particle diameter D of calcium carbonate particles50Preferably 25 μm or less, more preferably 24 μm or less, and still more preferably 23 μm or less. The volume cumulative particle diameter D of calcium carbonate is considered from the viewpoint of easiness in chirality introduction of calcium carbonate particles and homogeneity of mixing by aggregation50The lower limit of (B) is preferably set to 0.01 μm or more, for example.
For making D of alumina particles50Examples of the method within the above range include a method of pulverizing by a ball mill, a vibration mill, or the like, and a method of classifying by a sieve or the like. To make the calcium carbonate particles D50Examples of the method within the above range include a method of pulverizing by a ball mill, a vibration mill, or the like, and a method of classifying by a sieve or the like.
D50For example, the measurement can be carried out by Microtrac HRA and Microtrac 3000 series (for example, MT3200II, MT3300EXII, MT3300II and other MT-3000II series) manufactured by Nikkiso K.K. (or McKing Kabushiki Kaisha). When Microtrac HRA is used, the procedure is specifically as follows.
＜D50Method for measuring (1)
An amount containing about 0.4g of alumina particles or calcium carbonate particles was added to a 100mL glass beaker, and then pure water as a dispersion medium was added to a 100mL line of the beaker to form a slurry for measurement. The slurry for measurement was dropped into the chamber of a Microtrac HRA sample circulator made by Nikkiso K.K., to which pure water was added until the concentration of the slurry was judged to be appropriate, and D was obtained50。
The crystal structure of the alumina particles may be any of α, γ, θ, η, δ, and the like.
Examples of the calcium carbonate particles include heavy calcium carbonate particles and light calcium carbonate particles. The ground calcium carbonate particles are particles obtained by mechanically pulverizing and processing natural chalk (white earth powder), limestone, marble, and the like. On the other hand, light calcium carbonate is a synthetic calcium carbonate obtained by chemical production using limestone as a raw material. In the present production method, ground calcium carbonate particles are preferably used in order to make the merle ceramic more resistant to thermal expansion.
In addition, when particles not surface-treated with an organic compound are used as calcium carbonate particles, a calcium meteorite ceramic which is further less likely to thermally expand can be obtained, which is preferable. Examples of the organic compound include fatty acids, fatty acid esters, and fatty acid salts.
The ratio of the alumina particles to the calcium carbonate particles is such that the calcium aluminate constituting the resulting merle ceramic is CaAl4O7A single phase composition of matter is important. The mixing ratio of the alumina particles to the calcium carbonate particles is preferably set to 1.99:1 to 2.01:1 in terms of a molar ratio (calcium carbonate/alumina), and more preferably set to 1.995:1 to 2.005: 1.
The mixed powder of the raw materials may be a mixed powder containing only alumina particles and calcium carbonate particles, or may contain other minerals in addition to the alumina particles and the calcium carbonate particles. In addition, a binder may also be added. Examples of the binder include glass and silica.
Various molding methods for obtaining a molded body as a precalciner ceramic precursor using the mixed powder of the raw materials may use, for example, oil press molding or cast molding. In the case of oil pressure molding, 25 to 100 mass% of water is added to the mixed powder to form a water-containing fluid, and the water-containing fluid is filled in a cavity of a mold and pressure-molded. The press molding may employ, for example, biaxial pressing. The pressurizing force is preferably set to 100 to 1000kg/cm2. By adjusting the pressurizing force, the bulk specific gravity, the porosity and the bending strength of the obtained merle-baume ceramic can be adjusted. The molded article thus obtained was dried to remove moisture, and then fired.
On the other hand, when the casting molding is performed, water is preferably added in an amount of 25 to 100 mass% and a dispersant is preferably added in an amount of 0.5 to 3.0 mass% to the mixed powder to form a slurry. As the dispersant, for example, a polycarboxylic acid-based dispersant or the like can be used. Next, the resulting slurry is poured into a gypsum mold and allowed to cure. After the mold is released from the gypsum mold, the molded article obtained by drying and removing water is fired.
The molded articles obtained by various molding methods are fired under an oxygen-containing atmosphere such as the atmosphere at a firing temperature of 1450 ℃ or higher, whereby the intended merle ceramics are obtained. In the present production method, the particle size of the raw material and the firing temperature condition of 1450 ℃ or higher need to be satisfied at the same time. When any requirement is not satisfied, I is obtainedB/IAThe value of (A) is higher than the above upper limit, and the thermal expansion coefficient to 300 ℃ is higher than the above upper limit. In order to easily obtain the merle ceramic which is less likely to thermally expand, the lower limit of the firing temperature is preferably 1450 ℃ or higher, and more preferably 1500 ℃ or higher. From the viewpoint of the melting point (1760 ℃) of the material, the upper limit of the firing temperature is, for example, preferably 1750 ℃ or less, and more preferably 1730 ℃ or less. When the firing temperature is within this range, the maximum temperature holding time is preferably set to 1 to 10 hours.
The thus obtained merle ceramic of the present invention has both low thermal expansion properties and peeling resistance during high-temperature heating, and therefore can be suitably used for various applications such as aluminum molten metal parts in addition to kiln furniture. The kiln furniture can be suitably used for rapid firing of electronic parts and powder metallurgy.
The kiln furniture of the present invention is a kiln furniture using the merle-bauxite ceramic of the present invention. Examples of the kiln furniture include a tray, a pot, a sagger, and a container. Examples of the kiln furniture include rectangular and circular plate-like kiln furniture placed on a hearth of a firing furnace. Alternatively, the kiln furniture may be a kiln furniture having a rectangular or circular bottom portion placed on the hearth of the firing furnace and a closed wall portion that is opened upward and that rises from the periphery of the bottom portion. Alternatively, the kiln furniture may be used in the form of a container by combining a frame and a plate.
The kiln furniture of the present invention is particularly suitable for use as a kiln furniture for rapid firing of electronic parts. When the kiln furniture of the present invention is used as a rapid-firing kiln furniture for electronic parts, the kiln furniture is firedThe obtained electronic component includes, for example, a ceramic electronic component such as a multilayer ceramic capacitor (hereinafter referred to as MLCC). MLCCs can be manufactured, for example, as follows: mixing an internal electrode material such as nickel powder, BaTiO3The dielectric material is kneaded with a binder or the like to form a paste, and the paste is alternately laminated in a screen printing or other manner to form a sheet, cut into a predetermined size, and then an external electrode is attached and fired. The firing of electronic components such as MLCCs is carried out by charging a furnace having a high temperature range of 1200 to 1450 ℃. The firing atmosphere may be a weakly reducing atmosphere or an inert atmosphere using nitrogen and hydrogen. The average temperature increase rate from the room temperature in the furnace to the maximum holding temperature is, for example, 20 ℃/min or more, particularly 50 ℃/min or more, as the temperature increase rate in the rapid firing. The cooling rate is an average cooling rate from the maximum holding temperature in the furnace to room temperature of 20 ℃/min or more, particularly 50 ℃/min or more. The kiln furniture of the present invention uses merle-bauxite ceramics having a very low degree of thermal expansion and high spalling resistance. This can reduce the running cost and improve the yield of electronic components. When the kiln furniture is used for rapid firing of electronic components, the surface may be coated with zirconium oxide or the like in order to more reliably prevent a reaction with the electronic components.
Examples
The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited by the above-described embodiments. Unless otherwise specified, "%" means "% by mass". Further, "part" means "part by mass".
[ example 1]
Will D5067.1 parts of 0.4 μm alumina particles, D5032.9 parts of 2 μm calcium carbonate particles (heavy; without surface treatment), a PVA 20% aqueous solution, and 1 part of a polycarboxylic acid dispersant (Poise 532A, King, Ltd.) were mixed to obtain a slurry. An aqueous PVA solution was added so that the amount of PVA in the slurry was 1%. The slurry was dried at 90 ℃ and the dried product was granulated with a sieve (mesh size: 250 μm) to obtainThe particles are obtained. The pellets were filled in a mold and molded by uniaxial pressing. The applied pressure was set at 700kg/cm2. The molded article thus obtained was baked in an atmospheric furnace at 1600 ℃ for 3 hours to obtain the desired Medite ceramic. The Merle ceramic is in the form of a plate having a length of 110mm, a width of 110mm and a height of 4 mm.
The bulk specific gravity, porosity (%), and flexural strength (MPa) of the obtained merle ceramic were measured by the methods described above. The results are shown in Table 1.
Furthermore, the resulting merle ceramics were subjected to powder X-ray diffraction measurement under the following conditions to obtain the integrated intensity I of each target peakBAnd IAAnd calculate IB/IA. The results are shown in Table 2. The graph obtained by powder X-ray diffraction measurement is shown in fig. 1.
Further, the obtained merle ceramics were subjected to thermomechanical analysis under the following conditions to obtain a thermal expansion coefficient (/ K) from 27 ℃ to 300 ℃ and a thermal expansion coefficient (/ K) from 27 ℃ to 800 ℃, and a size-temperature graph was obtained to confirm the shape of the graph. These results are shown in Table 2. The obtained graph is shown in fig. 2. As shown in fig. 2, hysteresis is observed in the graph. Based on the graph, the ratio (%) between the maximum value of the difference between the temperature-increasing size and the cooling size at the same temperature and the size before the test was measured. The results are shown in Table 2.
Further, the obtained merle ceramic was observed with a microscope under the following conditions in cross section, and the number of microcracks per visual field, the total length (μm) in the longitudinal direction of the microcracks per visual field, and the crystal grain size (μm) were determined. These results are shown in Table 2. Fig. 3 and 4 show a photograph of a cross section obtained when microcracks are observed and a photograph of a cross section obtained when crystal grain sizes are observed, respectively.
Further, the exfoliation resistance Δ T of the obtained merle ceramic was determined under the following conditions. The deflection (mm) of the obtained merle ceramic was determined under the following conditions. These results are shown in Table 2.
Examples 2 to 7 and comparative examples 1 to 2
A meteorite ceramic was obtained in the same manner as in example 1, except that the particle size of alumina, the type of calcium carbonate, the presence or absence of surface treatment and the particle size, the molar ratio of alumina to calcium carbonate, and the firing temperature were changed as described in table 1 below. The resulting Merle ceramic was evaluated in the same manner as in example 1. The results are shown in tables 1 and 2. FIG. 5 shows a graph of the size-temperature curve at elevated temperature obtained by thermomechanical analysis of the Merle ceramic obtained in example 3.
In addition, fatty acid was used as a surface treatment agent for the surface treatment of calcium carbonate used in example 7. In addition, "heavy" of the calcium carbonate in table 1 means "heavy" and "light" means "light".
[ evaluation method ]
< powder X-ray diffraction measurement >
An apparatus: MiNi FLex600 (manufactured by Physics Co., Ltd.)
Source of radiation: cu ray
Tube voltage: 40kV
Tube current: 15mA
Scanning speed: 20 degree/min
Step size: 0.01 degree
Scan range: 2 theta is 10-70 DEG
< thermomechanical analysis >
A5X 20mm test piece made of the Merle ceramic of the present invention was mounted on a differential thermomechanical analysis (TMA) apparatus manufactured by Physco corporation, Thermoplus TMA 8310. The temperature was raised from 27 ℃ to 300 ℃ or from 27 ℃ to 800 ℃ at a rate of 5 ℃/min under an atmospheric atmosphere. The load was set to 0.5N. For reference, alumina having the same size as the test piece was set in a thermomechanical analyzer (TMA) apparatus, and the temperature was similarly raised, and the dimensional difference Δ La between the alumina and the test piece was measured. The thermal expansion coefficient was calculated from the following equation, taking the elongation of alumina in this period as Δ Lb.
The coefficient of thermal expansion (/ K) ═ Δ La + Δ Lb)/(lxΔ t) (in the above formula, L is the length of the test piece before the test, and Δ t is the temperature difference at the time of elongation measured)
The test piece was heated from 27 ℃ to 800 ℃ at a rate of 5 ℃/min by the thermomechanical analysis (TMA) apparatus, and then cooled at the rate in the temperature range. During this period, the length of the test piece was measured every five seconds, and the elongation Δ L of the test piece, which is the difference between the lengths of the test pieces at the respective measurement times and the test piece before the test, was obtained, thereby obtaining a dimension-temperature graph. The holding time at 800 ℃ after the temperature rise and before the transition to cooling was set to 5 minutes.
< microscopic Observation of Cross section >
The cross section obtained by cutting the merlinite ceramic with the diamond cutter was ground with SiC abrasive paper and diamond slurry. The sample was observed by a scanning electron microscope (SEM; JSM-6380A manufactured by Japan Electron Seisaku-Sho, Ltd.) under an acceleration voltage of 15kV, and a 150-fold photograph was taken. The number of microcracks having a length of 50 μm or more in the longitudinal direction in ten fields of view in each of the fields of view having a real size of 0.84mm × 0.59mm in the merle ceramic was counted, and the average value thereof was determined. Further, with the SEM photograph shown in fig. 3, the microcracks are shown as elongated white images. In addition, in the merle ceramics of each example, one or more microcracks having a length of 50 μm or more in the longitudinal direction were observed in all of the ten visual fields.
Next, in the microscopic observation, the total length (μm) of microcracks having a length of 50 μm or more in the longitudinal direction in each of ten fields was counted, and the average value thereof was obtained.
Next, the cross section of the merle ceramic was polished, and then the polished surface was fired in the atmosphere (held at 1400 ℃ c.. times.0 minutes) in a firing furnace, and then subjected to thermal etching. Next, the etched surface was observed and photographed at 1500 times using a Scanning Electron Microscope (SEM) under an acceleration voltage of 15kV, and an image was obtained. The code length of the obtained image was measured by the intercept method, and the crystal particle size was calculated. Ten lines parallel to the direction along the long side of the rectangular image were measured for one field, and the measurement was performed in arbitrarily different ten fields, and the average value of the observed crystal grain sizes was calculated for each field. The image used to determine the crystal grain size is shown in fig. 4. In fig. 4, an example of the grain boundary is shown by an arrow.
< spalling resistance DeltaT >
A test piece of the Mealite ceramic of each example and comparative example was prepared, which was processed to have a length of 100mm, a width of 100mm and a height of 2 mm. In addition, a column of alumina bricks having a length of 15mm, a width of 8mm and a height of 7mm was prepared. Four support columns were placed on the bottom plate at positions opposite to the four corners of the test body, and a piece of the test body was placed thereon. A plate of alumina bricks having a length of 68mm, a width of 68mm and a height of 16mm, in which an electronic component to be fired was assumed, was placed on the test body. The above-described placement state is shown in fig. 6. In fig. 6, the test body is denoted by symbol S, the support is denoted by symbol P, and the board on which the electronic component is assumed is denoted by symbol M. The electric furnace was heated (heating rate: 200 ℃/hr) to a predetermined temperature and held for 30 minutes, and then the test piece in the state of FIG. 6 was placed in the furnace for each base plate. After holding at this temperature for 60 minutes, the test bodies were taken out of the oven and left in the atmosphere (temperature T) on a per-floor basis1) And (5) cooling. The test piece was visually checked for cracking and cutting. The temperature was raised from 400 ℃ to 50 ℃ and the upper limit T of the temperature at which cracking did not occur was measured2With T2Minus T1The value obtained is the peel resistance Δ T.
< flexural test >
A sample of Mediterranite ceramic processed into 100mm × 30mm × 3mm was placed so that both ends in the longitudinal direction passed over two square bars separated by 90mm as span (the length in the longitudinal direction parallel to the Mediterranite ceramic was 20mm, the length in the width direction was 200mm, and the height was 10mm), a refractory of 10mm × 10mm × 30mm was placed in the center of the sample, and 4kg/cm was applied to the refractory2The load mode of the device is adjusted and the weight is placed. The resultant was heated in an atmospheric firing furnace at 1200 ℃ (heating rate: 200 ℃/hr, holding time: 3 hours), and the amount of warpage before and after firing was measured.
As the amount of warping, a hole was formed in the center of a standard non-warped aluminum bar (200 mm. times.50 mm), the warped portion was superimposed on the aluminum bar in a state of projecting upward, and the length measuring portion of a digital indicator was inserted into the hole from below, and the distance between the aluminum bar and the calalite ceramic was measured.
TABLE 1
As shown in Table 2, in respect of IB/IAHas a value of 0.05 or less and a coefficient of thermal expansion of 2.0X 10 measured under an atmospheric atmosphere at 27 ℃ to 300 DEG C-6The merle ceramics of the examples below/K have a low coefficient of thermal expansion from 27 ℃ to 800 ℃, improved spalling resistance, a small high temperature deflection, and are not easily softened at high temperatures. And a coefficient of thermal expansion from 27 ℃ to 300 ℃ of more than 2.0X 10-6The Merle ceramic of comparative example 1/K has a high coefficient of thermal expansion from 27 ℃ to 800 ℃ and a reduced spalling resistance; is as followsB/IAThe Mealite ceramic of comparative example 2 having a value of (1) greater than 0.05 has a large deflection amount and becomes easily softened at high temperature.
As is clear from the above, the meteorite ceramic of the present invention has high spalling resistance and can be used for a long time in a high-temperature firing step of electronic parts, and therefore, is suitable as kiln furniture, particularly, kiln furniture for rapid firing.
Description of the symbols
S test body
P pillar
M Board with electronic component
Claims (12)
1. A hydrocalumite ceramic derived from CaAl in X-ray diffraction2O4I.e., the integrated intensity I of the peak at 30.07 degrees 2 θ, which is the main peak of (a)BAnd from CaAl in X-ray diffraction4O7I.e., the integrated intensity I of the peak at 25.47 degrees 2 θ, which is the main peak of (a)ARatio of (I)B/IAThe value of (A) is 0.05 or less,
having a coefficient of thermal expansion of 2.0X 10 measured by thermomechanical analysis in an atmospheric atmosphere from 27 ℃ to 300 ℃-6The ratio of the total carbon content to the total carbon content is below K,
having a coefficient of thermal expansion of 3.4X 10 measured by thermomechanical analysis in an atmospheric atmosphere from 27 ℃ to 800 ℃-6The ratio of the total carbon content to the total carbon content is below K,
among them, in the thermomechanical analysis when heating was performed under an atmospheric atmosphere, a temperature region in which the size was reduced or a smooth temperature region in which the size was not substantially changed was observed in the obtained size-temperature graph.
2. The Merle ceramic of claim 1, wherein the reduced-size temperature region and the plateau temperature region having substantially no change in size are observed in a thermomechanical analysis from 27 ℃ to 600 ℃ measured under an atmospheric atmosphere,
in a graph having Δ L/L as a vertical axis and a temperature T as a horizontal axis, a minimum temperature T in a temperature region having a reduced sizeLAnd maximum temperature THDifference of difference, namely TH-TLThe temperature of the mixture is more than 150 ℃,
lowest temperature T 'in a plateau temperature region of substantially unchanged dimension'LAnd highest temperature T'HThe difference is T'H-T’LThe temperature of the mixture is more than 150 ℃,
the temperature region in which the dimension is substantially unchanged and which is stable means a region in which the thermal expansion amount is 0.01% or less with respect to the dimension L before the test.
3. The hydrocalumite ceramic of claim 1A coefficient of thermal expansion of 1.0X 10 measured by thermomechanical analysis in an atmospheric atmosphere at from 27 ℃ to 300 ℃-6and/K is less than or equal to.
4. The Mealite ceramic according to any one of claims 1 to 3, wherein, in thermomechanical analysis when heated from 27 ℃ to 600 ℃ in an atmospheric atmosphere, the resulting size-temperature profile is a curve that is convex toward a decrease in size or a curve that has a smooth temperature region with substantially no change in size and a temperature region of increasing size contiguous thereto.
5. The Mealite ceramic of any one of claims 1 to 3, wherein hysteresis is observed in the resulting size-temperature plot in thermomechanical analysis when heated from 27 ℃ to 800 ℃ in an atmospheric atmosphere and then cooled at that temperature range.
6. The Merle ceramic according to claim 5, wherein a maximum value of a difference between a size at a temperature rise and a size at a cooling time due to the hysteresis at the same temperature is 0.02% or more with respect to a size of the Merle ceramic before thermomechanical analysis.
7. The Merle ceramic according to any one of claims 1 to 3, wherein microcracks are observed in a microscope image with a cross section enlarged by 150 times,
the microcracks are in the shape of a width direction and a length direction longer than the width direction,
the microcracks having a length of 50 μm or more in the longitudinal direction are observed at the magnification of one or more per 0.84mm × 0.59mm of field.
8. The hydrocalumite ceramic of claim 7 wherein the total length of the microcracks having a length of 50 μm or more in the lengthwise direction in each field of view is 1000 μm or more.
9. The Mealite ceramic according to any one of claims 1 to 3, wherein the average crystal grain size observed in a microscopic image of a cross section is 5 μm or more.
10. The hydrocalumite ceramic according to any one of claims 1 to 3, wherein the exfoliation resistance Δ T is 600 ℃ or higher.
11. A kiln furniture using the Merle ceramic according to any one of claims 1 to 10.
12. A method for producing the Megalalite ceramic according to any one of claims 1 to 10, comprising the steps of:
volume cumulative particle diameter D at 50 vol% cumulative volume in the laser diffraction scattering particle size distribution measurement method50Alumina particles of 5 μm or less and the volume cumulative particle diameter D50Molding a mixed powder of calcium carbonate particles having a particle size of 25 μm or less, and firing the molded article at a temperature of 1450 ℃ or higher.
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| JP2015177380 | 2015-09-09 | ||
| JP2015-177380 | 2015-09-09 | ||
| PCT/JP2016/059826 WO2017043115A1 (en) | 2015-09-09 | 2016-03-28 | Grossite ceramics, kiln equipment using same, and method for manufacturing grossite ceramics |
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| US6809051B2 (en) * | 2002-05-01 | 2004-10-26 | Corning Incorporated | Fabrication of low thermal expansion calcium aluminate articles |
| US6689707B1 (en) * | 2003-04-01 | 2004-02-10 | Corning Incorporated | Low thermal expansion calcium aluminate articles |
| CN101077785B (en) * | 2006-05-26 | 2011-05-11 | 中国科学院金属研究所 | Nano CaAl4O7 material and preparing method thereof |
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| JPWO2017043115A1 (en) | 2017-11-02 |
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