WO2015056674A1 - Inorganic porous film and method for producing inorganic porous film - Google Patents

Inorganic porous film and method for producing inorganic porous film Download PDF

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WO2015056674A1
WO2015056674A1 PCT/JP2014/077349 JP2014077349W WO2015056674A1 WO 2015056674 A1 WO2015056674 A1 WO 2015056674A1 JP 2014077349 W JP2014077349 W JP 2014077349W WO 2015056674 A1 WO2015056674 A1 WO 2015056674A1
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glass
inorganic porous
porous membrane
membrane according
inorganic
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PCT/JP2014/077349
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French (fr)
Japanese (ja)
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清行 奥長
小林　正宏
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日本電気硝子株式会社
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
    • G01N27/4072—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure characterized by the diffusion barrier

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  • the present invention relates to an inorganic porous membrane and a method for producing an inorganic porous membrane.
  • Patent Documents 1 and 2 describe an example of an air-fuel ratio sensor that is a kind of exhaust gas sensor.
  • the air-fuel ratio sensor described in Patent Document 1 has a solid electrolyte layer made of oxygen ion conductive ceramics such as zirconia.
  • the solid electrolyte layer is sandwiched between the exhaust gas side electrode layer and the atmosphere side electrode layer.
  • a diffusion resistance layer is provided on the exhaust gas side electrode layer.
  • the diffusion resistance layer has a function of limiting the amount of oxygen ions transferred in the solid electrolyte layer.
  • Patent Document 1 describes that the diffusion resistance layer is made of porous ceramics (heat-resistant inorganic substance).
  • the air-fuel ratio sensor described in Patent Document 2 describes that a diffusion resistance layer can be formed of alumina or the like.
  • Exhaust gas sensors used in automobiles and the like are required to have excellent thermal shock resistance.
  • the diffusion resistance layer made of alumina has low thermal shock resistance.
  • an exhaust gas sensor provided with a diffusion resistance layer made of alumina has a problem of low thermal shock resistance.
  • the main object of the present invention is to provide an inorganic porous membrane capable of producing an exhaust gas sensor excellent in thermal shock resistance.
  • the inorganic porous membrane according to the present invention contains glass and an inorganic filler, and the glass content is 50% by volume or less.
  • the inorganic filler is made of crystallized glass, quartz glass, ⁇ -spodumene, ⁇ -eucryptite, willemite, cordierite, aluminum titanate, zirconium tungstate and zirconium phosphotungstate. It is preferable to consist of at least one selected from the group consisting of
  • the inorganic filler is preferably made of crystallized glass containing ⁇ -spodumene solid solution or ⁇ -quartz solid solution as precipitated crystals.
  • the glass is preferably made of silica borate glass.
  • the silica borate glass is, by mass%, SiO 2 25 to 70%, B 2 O 3 1 to 50%, MgO 0 to 10%, CaO 0 to 25%, SrO 0. It is preferable to contain ⁇ 10%, BaO 0 ⁇ 40%, MgO + CaO + SrO + BaO 10 ⁇ 45%, Al 2 O 3 0 ⁇ 20%, and ZnO 0 ⁇ 25%.
  • the total content of alkali metal components in the silica borate glass is preferably 10% by mass or less.
  • the inorganic porous membrane according to the present invention preferably has a thermal expansion coefficient of 70 ⁇ 10 ⁇ 7 / ° C. or less.
  • the glass preferably has a thermal expansion coefficient of 100 ⁇ 10 ⁇ 7 / ° C. or less.
  • the thermal expansion coefficient of the inorganic filler is preferably 70 ⁇ 10 ⁇ 7 / ° C. or less.
  • the softening temperature of the glass is preferably 400 ° C. to 1100 ° C.
  • the average particle diameter (D 50 ) of the inorganic filler is 2 ⁇ m to 50 ⁇ m.
  • the ratio (D 99 / D 50 ) of 99% particle diameter (D 99 ) to the average particle diameter (D 50 ) of the inorganic filler is preferably 3 to 100.
  • the porosity of the inorganic porous membrane according to the present invention is preferably 20% to 80%.
  • the inorganic porous membrane according to the present invention is preferably used for a diffusion resistance layer of an exhaust gas sensor.
  • the method for producing an inorganic porous membrane according to the present invention is a method for producing the inorganic porous membrane.
  • a paste layer made of a paste containing glass powder and an inorganic filler is fired.
  • the paste layer is preferably baked at a temperature of the glass softening temperature to the glass softening temperature + 400 ° C.
  • the glass powder preferably has an average particle diameter (D 50 ) of 0.5 ⁇ m to 20 ⁇ m.
  • the average particle size (D 50 ) of the glass powder is smaller than the average particle size (D 50 ) of the inorganic filler.
  • an inorganic porous membrane capable of producing an exhaust gas sensor excellent in thermal shock resistance can be provided.
  • FIG. 1 is a schematic cross-sectional view of a main part of an exhaust gas sensor using an inorganic porous film according to an embodiment of the present invention as a diffusion resistance layer.
  • FIG. 2 is a photomicrograph of a fracture surface of the diffusion resistance layer in Sample 1.
  • FIG. 3 is a photomicrograph of a fracture surface of the diffusion resistance layer in Sample 2.
  • FIG. 4 is a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 4.
  • FIG. 5 is a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 5.
  • FIG. 6 is a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 6.
  • FIG. 1 is a schematic cross-sectional view of a main part of an exhaust gas sensor using an inorganic porous film according to this embodiment as a diffusion resistance layer. As shown in FIG. 1, the exhaust gas sensor 1 has a solid electrolyte layer 10.
  • the solid electrolyte layer 10 can be made of, for example, ceramic having conductivity with respect to oxygen ions contained in the exhaust gas.
  • the solid electrolyte layer 10 can be composed of partially stabilized zirconia such as zirconia and yttrium partially stabilized zirconia, ceria, and the like.
  • the solid electrolyte layer 10 composed of partially stabilized zirconia such as zirconia or yttrium partially stabilized zirconia, ceria, etc. exhibits conductivity with respect to oxygen ions or the like when heated to a high temperature of about 500 ° C., for example. Therefore, the exhaust gas sensor 1 is used by being heated to a temperature at which the solid electrolyte layer 10 exhibits conductivity with respect to oxygen ions and the like.
  • the exhaust gas sensor 1 usually includes a heating mechanism for the solid electrolyte layer 10.
  • the solid electrolyte layer 10 has a first main surface 10a and a second main surface 10b.
  • a first electrode 11 is provided on the first main surface 10a.
  • a second electrode 12 is provided on the second main surface 10b.
  • the solid electrolyte layer 10 is sandwiched between the first electrode 11 and the second electrode 12.
  • the first and second electrodes 11 and 12 each have air permeability. Therefore, oxygen contained in the exhaust gas can pass through the first and second electrodes 11 and 12 in the thickness direction.
  • the first and second electrodes 11 and 12 may be, for example, a porous film or may be provided in a mesh shape.
  • the first and second electrodes 11 and 12 can each be composed of a noble metal having high catalytic activity such as Pt.
  • the exhaust gas sensor 1 When the exhaust gas sensor 1 is disposed in an exhaust path of an automobile or the like, the exhaust gas sensor 1 is disposed such that the first electrode 11 faces the engine side and the second electrode 12 faces the outside air side.
  • an oxygen sensor which is a kind of exhaust gas sensor
  • the oxygen concentration in the atmosphere on the first electrode 11 side and the oxygen concentration in the atmosphere on the second electrode 12 side are different, the oxygen concentration is increased from the side with the higher oxygen concentration.
  • An oxygen ion stream is generated toward the lower side.
  • an electromotive force is generated.
  • the exhaust gas sensor 1 can be applied to an air-fuel ratio sensor that can detect a continuous change in air-fuel ratio, a NO x sensor that can detect NO x concentration, and the like. .
  • a diffusion resistance layer 13 covering the first electrode 11 is provided on the first main surface 10a.
  • the diffusion resistance layer 13 is a layer having a function of limiting the amount of exhaust gas supplied to the solid electrolyte layer 10.
  • the diffusion resistance layer 13 is made of a porous body having open cells. For this reason, the exhaust gas can pass through the diffusion resistance layer 13 in the thickness direction.
  • the thickness of the diffusion resistance layer 13 is preferably 50 ⁇ m to 500 ⁇ m, more preferably 60 ⁇ m to 300 ⁇ m, and even more preferably 70 ⁇ m to 200 ⁇ m in order to obtain a desired exhaust gas diffusion resistance capability.
  • the diffusion resistance layer 13 includes glass and an inorganic filler.
  • the glass content in the diffusion resistance layer 13 is 50% by volume or less. For this reason, as can be seen from the results of the following experimental examples and the like, the diffusion resistance layer 13 has good porosity and high thermal shock resistance. Further, the diffusion resistance layer 13 has high adhesion with the solid electrolyte layer 10.
  • the diffusion resistance layer 13 is made of an inorganic porous film containing glass and an inorganic filler and having a glass content of 50% by volume or less, and has high thermal shock resistance and high adhesion to other members. Has strength.
  • the diffusion resistance layer 13 has a thermal expansion coefficient of ⁇ 10 ⁇ 10 ⁇ 7 / ° C. to 70 ⁇ 10 ⁇ 7 / ° C.
  • the thermal expansion coefficient is preferably ⁇ 10 ⁇ 10 ⁇ 7 / ° C. to 30 ⁇ 10 ⁇ 7 / ° C., more preferably 0 / ° C. to 15 ⁇ 10 ⁇ 7 / ° C. .
  • the glass contained in the diffusion resistance layer 13 preferably has a thermal expansion coefficient of 30 ⁇ 10 ⁇ 7 / ° C. to 100 ⁇ 10 ⁇ 7 / ° C., and 40 ⁇ 10 ⁇ 7 / ° C.
  • the inorganic filler contained in the diffusion resistance layer 13 preferably has a thermal expansion coefficient of ⁇ 80 ⁇ 10 ⁇ 7 / ° C. to 70 ⁇ 10 ⁇ 7 / ° C., and ⁇ 80 ⁇ 10 ⁇ 7 / ° C. to 40 ⁇ 10 ⁇ 7 / ° C. is more preferable, and ⁇ 10 ⁇ 10 ⁇ 7 / ° C. to 30 ⁇ 10 ⁇ 7 / ° C. is further preferable.
  • the thermal expansion coefficient means a linear thermal expansion coefficient in the range of 30 ° C. to 300 ° C.
  • Examples of the inorganic filler having a low coefficient of thermal expansion as described above include crystallized glass, quartz glass, ⁇ -spodumene, ⁇ -eucryptite, willemite, cordierite, aluminum titanate, zirconium tungstate, and phosphoric acid. Examples thereof include zirconium tungstate.
  • crystallized glass examples include crystallized glass containing ⁇ -spodumene solid solution as precipitated crystals, crystallized glass containing ⁇ -quartz solid solution as precipitated crystals, and the like.
  • the crystallization start temperature of the crystallized glass is preferably 700 ° C. or higher, and more preferably 750 ° C. or higher. If the crystallization start temperature is too low, the heat resistance of the diffusion resistance layer 13 may be reduced.
  • the diffusion resistance layer 13 may include one type of inorganic filler or may include a plurality of types of inorganic fillers.
  • the melting point of the inorganic filler is preferably higher than the softening temperature of the glass.
  • the average particle diameter (D 50 ) of the inorganic filler is preferably 2 ⁇ m to 50 ⁇ m, and more preferably 3 ⁇ m to 15 ⁇ m. If the average particle diameter (D 50 ) of the inorganic filler is too large, the mechanical strength of the porous body may be low, or a uniform porous body may not be obtained. If the average particle diameter (D 50 ) of the inorganic filler is too small, the pores may be too small and the exhaust gas may not pass easily.
  • the shape of the inorganic filler is not particularly limited, and examples thereof include a substantially spherical shape and an elliptical shape. Especially, when the inorganic filler is substantially spherical, the distribution of pores inside the diffusion resistance layer 13 is likely to be uniform, and as a result, the air permeability of the exhaust gas is easily stabilized.
  • the softening temperature of glass refers to a value measured with a DTA (differential thermal analyzer).
  • the ratio of the 99% particle diameter to the average particle diameter of the inorganic filler (D 50) (D 99) (D 99 / D 50) is preferably 3 or more, further preferably 5 or more. By doing so, the thermal shock resistance of the diffusion resistance layer 13 can be improved. However, if D 99 / D 50 is too high, the mechanical strength of the porous body may be lowered. Therefore, D 99 / D 50 is preferably 100 or less, and more preferably 30 or less.
  • the average particle size (D 50 ) and the 99% particle size (D 99 ) can be measured with a laser diffraction particle size distribution meter.
  • the glass content in the diffusion resistance layer 13 is higher.
  • the glass content in the diffusion resistance layer 13 is preferably 3% by volume or more, and more preferably 5% by volume or more.
  • the glass content in the diffusion resistance layer 13 needs to be 50% by volume or less, preferably 30% by volume or less, and more preferably 20% by volume or less.
  • the porosity of the diffusion resistance layer 13 can be appropriately set according to characteristics required for the diffusion resistance layer 13.
  • the porosity of the diffusion resistance layer 13 is preferably 20% to 80%, and more preferably 30% to 70%.
  • the softening temperature of the glass contained in the diffusion resistance layer 13 is preferably 1100 ° C. or less, and more preferably 1000 ° C. or less. If the softening temperature of the glass contained in the diffusion resistance layer 13 is too high, the inorganic filler may be altered during firing.
  • the lower limit of the softening temperature of the glass contained in the diffusion resistance layer 13 is not particularly limited, but is preferably 400 ° C. or higher in order to suppress softening deformation under the use environment of the exhaust gas sensor, that is, to improve heat resistance. It is more preferably 500 ° C. or higher, further preferably 600 ° C. or higher, particularly preferably 700 ° C. or higher, and most preferably 800 ° C. or higher.
  • the glass contained in the diffusion resistance layer 13 is preferably a silica borate glass from the viewpoint of heat resistance.
  • Specific examples of the silica borate glass include, by mass%, SiO 2 25 to 70%, B 2 O 3 1 to 50%, MgO 0 to 10%, CaO 0 to 25%, SrO 0 to 10%, BaO 0. -40%, MgO + CaO + SrO + BaO 10-45%, Al 2 O 3 0-20%, and ZnO 0-25%.
  • the alkali metal component Li 2 O, Na 2 O and K 2 O
  • the total content of alkali metal components is preferably 10% or less, more preferably 5% or less, further preferably 1% or less, and particularly preferably not contained.
  • the diffusion resistance layer 13 is provided only on the first main surface 10a.
  • the present invention is not limited to this configuration.
  • the diffusion resistance layer 13 may be provided on each of the first main surface 10a and the second main surface 10b.
  • the exhaust gas sensor 1 can be manufactured, for example, in the following manner. Here, only the manufacturing method of the main part of the exhaust gas sensor 1 will be described. The manufacturing method of other parts may be the same as the conventional method, for example.
  • the solid electrolyte layer 10 is prepared.
  • the first electrode 11 and the second electrode 12 are formed on the solid electrolyte layer 10.
  • the formation method of the 1st and 2nd electrodes 11 and 12 is not specifically limited.
  • the first and second electrodes 11 and 12 can be formed, for example, by sputtering, vapor deposition, plating, or the like.
  • a diffusion resistance layer 13 is formed on the first main surface 10a so as to cover the first electrode 11.
  • a paste containing glass powder and an inorganic filler is prepared.
  • the paste may contain a resin binder, a solvent and the like in addition to the glass powder and the inorganic filler.
  • the porosity of the diffusion resistance layer 13 can be increased (the pore diameter is increased) by adding fibrous crystalline cellulose to the paste.
  • the paste is applied on the first main surface 10a so as to cover the first electrode 11, and dried to form a paste layer (paste method). Thereafter, the diffusion resistance layer 13 can be formed by firing the paste layer.
  • you may perform the degreasing process which removes a resin binder, a solvent, etc. before baking of a paste layer.
  • the firing of the paste layer is preferably performed within the range of the glass softening temperature to the glass softening temperature + 400 ° C., more preferably within the range of the glass softening temperature + 50 ° C. to the glass softening temperature + 250 ° C. It is more preferable to carry out within the range of the softening temperature of the glass + 50 ° C. to the softening temperature of the glass + 200 ° C. If the firing temperature of the paste layer is too high, the resulting diffusion resistance layer 13 may not be a suitable porous body.
  • the firing temperature of the paste layer is too low, the firing does not proceed sufficiently and the thermal shock resistance of the obtained diffusion resistance layer 13 is lowered, or the adhesion between the diffusion resistance layer 13 and the solid electrolyte layer 10 is lowered. Sometimes.
  • the average particle diameter (D 50 ) of the glass powder is preferably 0.5 ⁇ m to 20 ⁇ m, and more preferably 2 ⁇ m to 10 ⁇ m. If the average particle diameter (D 50 ) of the glass powder is too large, a uniform porous body may not be obtained. If the average particle diameter (D 50 ) of the glass powder is too small, the strength of the porous body may be inferior.
  • the average particle diameter of the glass powder (D 50) is smaller than the average particle diameter of the inorganic filler (D 50) are preferred. That is, the ratio of the average particle diameter of the inorganic filler to the average particle diameter of the glass powder (D 50) (D 50) (average particle diameter of the inorganic filler (D 50) / average particle diameter (D 50 of the glass powder)) is 1 Larger is preferred.
  • the average particle diameter of the inorganic filler (D 50 ) / average particle diameter of the glass powder (D 50 ) is more preferably 3 or more, and even more preferably 10 or more.
  • the thickness of the glass wall formed around the inorganic filler can be reduced, and the diffusion resistance layer 13 can be reduced. It can be set as a suitable porous body. However, if the (average particle diameter of the inorganic filler (D 50 ) / average particle diameter of the glass powder (D 50 )) is too large, the strength of the porous body may decrease. Therefore, (average particle diameter of inorganic filler (D 50 ) / average particle diameter of glass powder (D 50 )) is preferably 50 or less, and more preferably 30 or less.
  • the example in which the solid electrolyte layer 10 is first prepared and then the paste layer for forming the diffusion resistance layer 13 is fired on the solid electrolyte layer 10 has been described.
  • These paste layers and a paste layer for forming the solid electrolyte layer 10 may be laminated and fired simultaneously.
  • the solid electrolyte layer 10 and the diffusion resistance layer 13 may be formed by a spray method, a dipping method, or the like.
  • a paste layer was formed on a zirconia substrate so that the coating thickness was 200 ⁇ m.
  • a zirconia substrate As a zirconia substrate, the surface of a dense zirconia manufactured by AS ONE (50 mm ⁇ 50 mm ⁇ 2 mm size divided into 4 ⁇ 25 mm ⁇ 25 mm ⁇ 2 mm) was polished with a diamond # 1000 electrodeposition polishing machine It was used. Thereafter, the paste layer was baked at 850 ° C. for 10 minutes to prepare Sample 1.
  • a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 1 is shown in FIG.
  • the porosity was calculated from the theoretical density and the apparent density by calculating the theoretical density from the density of the glass powder and the crystallized glass powder, determining the apparent density from the volume and mass of the sample.
  • the thermal expansion coefficient of the diffusion resistance layer was measured as follows. Raw material powder was put into a stainless steel mold, and after press molding, heat treatment was performed at the above temperature and time to obtain a sintered body. The obtained sintered body was processed into a diameter of about 5 mm and a length of about 20 mm to prepare a measurement sample. About the sample for a measurement, the thermal expansion coefficient was measured using the thermomechanical analyzer. The measurement conditions were a temperature increase rate of 10 ° C./min and a temperature range of 30 ° C. to 300 ° C.
  • Example 2 Sample 2 was produced in the same manner as in Experimental Example 1, except that the glass powder content was 10% by volume. A photomicrograph of the fracture surface of the diffusion resistance layer in Sample 2 is shown in FIG.
  • Example 3 Sample 3 was produced in the same manner as in Experimental Example 1 except that the firing temperature of the paste layer was 800 ° C.
  • Example 4 Sample 4 was produced in the same manner as in Experimental Example 2, except that the firing temperature of the paste layer was 800 ° C. A photomicrograph of the fracture surface of the diffusion resistance layer in Sample 4 is shown in FIG.
  • Example 5 Sample 5 was produced in the same manner as in Experimental Example 1, except that the glass powder content was 20% by volume and the paste layer was fired at 800 ° C. A micrograph of the fracture surface of the diffusion resistance layer in Sample 5 is shown in FIG.
  • Example 6 Instead of crystallized glass powder, alumina powder (FO-1000 manufactured by Fujimi Incorporated, average particle size (D 50 ): 12.7 ⁇ m, 99% particle size (D 99 ): 23 ⁇ m, thermal expansion coefficient: 60 to 70 ⁇ 10 ⁇ 7 / ° C.), and the content of glass powder ( ⁇ (volume content of glass powder) / (volume content of glass powder + volume content of alumina powder) ⁇ ⁇ 100) is 30% by volume.
  • a sample 6 was produced in the same manner as in Experimental Example 1 except for the above. A micrograph of the fracture surface of the diffusion resistance layer in Sample 6 is shown in FIG.
  • Example 7 Sample 7 was produced in the same manner as in Experimental Example 6 except that only the alumina powder was used without using the glass powder.
  • Example 8 As glass powder, silica borate glass GA-13 manufactured by Nippon Electric Glass Co., Ltd. (average particle size (D 50 ): 2.3 ⁇ m, 99% particle size (D 99 ): 6.8 ⁇ m, softening temperature: 848 ° C., heat Sample 8 was prepared in the same manner as in Experimental Example 1, except that the coefficient of expansion was 64.9 ⁇ 10 ⁇ 7 / ° C., the glass powder content was 8% by volume, and the paste layer firing temperature was 930 ° C. Produced.
  • Example 9 Sample 9 was prepared in the same manner as in Experimental Example 8, except that the glass powder content was 10% by volume and the paste layer firing temperature was 900 ° C.
  • Example 10 Sample 10 was produced in the same manner as in Experimental Example 8, except that the glass powder content was 55% by volume and the paste layer firing temperature was 900 ° C.
  • samples 8 and 9 were evaluated as ⁇ , and sample 10 was evaluated as ⁇ . Samples 8 and 9 were further evaluated for adhesion when the adhesion strength was measured.
  • the obtained samples 2 'and 9' were heat-treated at 750 ° C for 24 hours, and the change rate of the diameter and height after the heat treatment before the heat treatment was obtained by the following formula.
  • Diameter change rate ⁇ (diameter after heat treatment ⁇ diameter before heat treatment) / diameter before heat treatment ⁇ ⁇ 100 (%)
  • Change rate of height ⁇ (height after heat treatment ⁇ height before heat treatment) / diameter before heat treatment ⁇ ⁇ 100 (%)
  • exhaust gas sensor 10 solid electrolyte layer 10a: first main surface 10b of solid electrolyte layer: second main surface 11 of solid electrolyte layer 11: first electrode 12: second electrode 13: diffusion resistance layer

Abstract

[Problem] To provide an inorganic porous film that can produce an exhaust gas sensor having superior thermal shock resistance. [Solution] This inorganic porous film contains glass and an inorganic filler. The glass content in the inorganic porous film is no greater than 50 vol%.

Description

無機多孔質膜及び無機多孔質膜の製造方法INORGANIC POROUS MEMBRANE AND METHOD FOR PRODUCING INORGANIC POROUS MEMBRANE
　本発明は、無機多孔質膜及び無機多孔質膜の製造方法に関する。 The present invention relates to an inorganic porous membrane and a method for producing an inorganic porous membrane.
　従来、例えば自動車の排気通路等には、酸素ガスを検知する排気ガスセンサーが配されている。特許文献１及び２には、排ガスセンサーの一種である空燃比センサーの一例が記載されている。 Conventionally, for example, an exhaust gas sensor for detecting oxygen gas is arranged in an exhaust passage of an automobile or the like. Patent Documents 1 and 2 describe an example of an air-fuel ratio sensor that is a kind of exhaust gas sensor.
　特許文献１に記載の空燃比センサーは、ジルコニア等の酸素イオン導電性のセラミックスからなる固体電解質層を有する。固体電解質層は、排気ガス側電極層と大気側電極層とにより挟持されている。排気ガス側電極層の上には、拡散抵抗層が設けられている。 The air-fuel ratio sensor described in Patent Document 1 has a solid electrolyte layer made of oxygen ion conductive ceramics such as zirconia. The solid electrolyte layer is sandwiched between the exhaust gas side electrode layer and the atmosphere side electrode layer. A diffusion resistance layer is provided on the exhaust gas side electrode layer.
　拡散抵抗層は、固体電解質層における酸素イオンの移動量を制限する機能を有する。特許文献１には、拡散抵抗層を、多孔質セラミックス（耐熱性無機物質）により構成することが記載されている。また、特許文献２に記載の空燃比センサーには、アルミナ等により拡散抵抗層を構成できる旨が記載されている。 The diffusion resistance layer has a function of limiting the amount of oxygen ions transferred in the solid electrolyte layer. Patent Document 1 describes that the diffusion resistance layer is made of porous ceramics (heat-resistant inorganic substance). In addition, the air-fuel ratio sensor described in Patent Document 2 describes that a diffusion resistance layer can be formed of alumina or the like.
国際公開２０１１／０７４１３２号公報International Publication No. 2011-074132 特開２０１３－１５３９８号公報JP 2013-15398 A
　自動車等に用いられる排気ガスセンサーには、耐熱衝撃性に優れていることが要求される。しかしながら、アルミナからなる拡散抵抗層は耐熱衝撃性が低い。このため、アルミナからなる拡散抵抗層を備える排気ガスセンサーは、耐熱衝撃性が低いという問題を有する。 Exhaust gas sensors used in automobiles and the like are required to have excellent thermal shock resistance. However, the diffusion resistance layer made of alumina has low thermal shock resistance. For this reason, an exhaust gas sensor provided with a diffusion resistance layer made of alumina has a problem of low thermal shock resistance.
　本発明の主な目的は、耐熱衝撃性に優れた排気ガスセンサーを製造することが可能な無機多孔質膜を提供することにある。 The main object of the present invention is to provide an inorganic porous membrane capable of producing an exhaust gas sensor excellent in thermal shock resistance.
　本発明に係る無機多孔質膜は、ガラスと、無機フィラーとを含み、ガラスの含有率が５０体積％以下である。 The inorganic porous membrane according to the present invention contains glass and an inorganic filler, and the glass content is 50% by volume or less.
　本発明に係る無機多孔質膜では、無機フィラーは、結晶化ガラス、石英ガラス、β－スポジュメン、β－ユークリプタイト、ウイレマイト、コーディエライト、チタン酸アルミニウム、タングステン酸ジルコニウム及びリンタングステン酸ジルコニウムからなる群から選ばれた少なくとも一種からなることが好ましい。 In the inorganic porous membrane according to the present invention, the inorganic filler is made of crystallized glass, quartz glass, β-spodumene, β-eucryptite, willemite, cordierite, aluminum titanate, zirconium tungstate and zirconium phosphotungstate. It is preferable to consist of at least one selected from the group consisting of
　本発明に係る無機多孔質膜では、無機フィラーは、β－スポジュメン固溶体またはβ－石英固溶体を析出結晶として含有する結晶化ガラスからなることが好ましい。 In the inorganic porous membrane according to the present invention, the inorganic filler is preferably made of crystallized glass containing β-spodumene solid solution or β-quartz solid solution as precipitated crystals.
　本発明に係る無機多孔質膜では、ガラスは、シリカホウ酸系ガラスからなることが好ましい。 In the inorganic porous membrane according to the present invention, the glass is preferably made of silica borate glass.
　本発明に係る無機多孔質膜では、シリカホウ酸系ガラスは、質量％で、ＳｉＯ２　２５～７０％、Ｂ２Ｏ３　１～５０％、ＭｇＯ　０～１０％、ＣａＯ　０～２５％、ＳｒＯ　０～１０％、ＢａＯ　０～４０％、ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ　１０～４５％、Ａｌ２Ｏ３　０～２０％、及びＺｎＯ　０～２５％含有することが好ましい。 In the inorganic porous membrane according to the present invention, the silica borate glass is, by mass%, SiO 2 25 to 70%, B 2 O 3 1 to 50%, MgO 0 to 10%, CaO 0 to 25%, SrO 0. It is preferable to contain ~ 10%, BaO 0 ~ 40%, MgO + CaO + SrO + BaO 10 ~ 45%, Al 2 O 3 0 ~ 20%, and ZnO 0 ~ 25%.
　本発明に係る無機多孔質膜では、シリカホウ酸系ガラスにおけるアルカリ金属成分の含有量の合量が、質量％で１０％以下であることが好ましい。 In the inorganic porous membrane according to the present invention, the total content of alkali metal components in the silica borate glass is preferably 10% by mass or less.
　本発明に係る無機多孔質膜は、熱膨張係数が７０×１０－７／℃以下であることが好ましい。 The inorganic porous membrane according to the present invention preferably has a thermal expansion coefficient of 70 × 10 −7 / ° C. or less.
　本発明に係る無機多孔質膜では、ガラスの熱膨張係数が１００×１０－７／℃以下であることが好ましい。 In the inorganic porous membrane according to the present invention, the glass preferably has a thermal expansion coefficient of 100 × 10 −7 / ° C. or less.
　本発明に係る無機多孔質膜では、無機フィラーの熱膨張係数が７０×１０－７／℃以下であることが好ましい。 In the inorganic porous membrane according to the present invention, the thermal expansion coefficient of the inorganic filler is preferably 70 × 10 −7 / ° C. or less.
　本発明に係る無機多孔質膜では、ガラスの軟化温度が４００℃～１１００℃であることが好ましい。 In the inorganic porous membrane according to the present invention, the softening temperature of the glass is preferably 400 ° C. to 1100 ° C.
　本発明に係る無機多孔質膜では、無機フィラーの平均粒子径（Ｄ５０）が２μｍ～５０μｍであることが好ましい。 In the inorganic porous membrane according to the present invention, it is preferable that the average particle diameter (D 50 ) of the inorganic filler is 2 μm to 50 μm.
　本発明に係る無機多孔質膜では、無機フィラーの平均粒子径（Ｄ５０）に対する９９％粒子径（Ｄ９９）の比（Ｄ９９／Ｄ５０）が３～１００であることが好ましい。 In the inorganic porous membrane according to the present invention, the ratio (D 99 / D 50 ) of 99% particle diameter (D 99 ) to the average particle diameter (D 50 ) of the inorganic filler is preferably 3 to 100.
　本発明に係る無機多孔質膜は、気孔率が２０％～８０％であることが好ましい。 The porosity of the inorganic porous membrane according to the present invention is preferably 20% to 80%.
　本発明に係る無機多孔質膜は、排気ガスセンサーの拡散抵抗層に用いられることが好ましい。 The inorganic porous membrane according to the present invention is preferably used for a diffusion resistance layer of an exhaust gas sensor.
　本発明に係る無機多孔質膜の製造方法は、上記無機多孔質膜を製造するための方法である。本発明に係る無機多孔質膜の製造方法では、ガラス粉末と無機フィラーとを含むペーストからなるペースト層を焼成する。 The method for producing an inorganic porous membrane according to the present invention is a method for producing the inorganic porous membrane. In the method for producing an inorganic porous membrane according to the present invention, a paste layer made of a paste containing glass powder and an inorganic filler is fired.
　本発明に係る無機多孔質膜の製造方法では、ガラスの軟化温度～ガラスの軟化温度＋４００℃の温度でペースト層を焼成することが好ましい。 In the method for producing an inorganic porous membrane according to the present invention, the paste layer is preferably baked at a temperature of the glass softening temperature to the glass softening temperature + 400 ° C.
　本発明に係る無機多孔質膜の製造方法では、ガラス粉末の平均粒子径（Ｄ５０）が０．５μｍ～２０μｍであることが好ましい。 In the method for producing an inorganic porous membrane according to the present invention, the glass powder preferably has an average particle diameter (D 50 ) of 0.5 μm to 20 μm.
　本発明に係る無機多孔質膜の製造方法では、ガラス粉末の平均粒子径（Ｄ５０）が、無機フィラーの平均粒子径（Ｄ５０）よりも小さいことが好ましい。 In the method for producing an inorganic porous membrane according to the present invention, it is preferable that the average particle size (D 50 ) of the glass powder is smaller than the average particle size (D 50 ) of the inorganic filler.
　本発明によれば、耐熱衝撃性に優れた排気ガスセンサーを製造することが可能な無機多孔質膜を提供することができる。 According to the present invention, an inorganic porous membrane capable of producing an exhaust gas sensor excellent in thermal shock resistance can be provided.
図１は、本発明の一実施形態に係る無機多孔質膜を拡散抵抗層として用いた排気ガスセンサーの要部の模式的断面図である。FIG. 1 is a schematic cross-sectional view of a main part of an exhaust gas sensor using an inorganic porous film according to an embodiment of the present invention as a diffusion resistance layer. 図２は、サンプル１における拡散抵抗層の破断面の顕微鏡写真である。FIG. 2 is a photomicrograph of a fracture surface of the diffusion resistance layer in Sample 1. 図３は、サンプル２における拡散抵抗層の破断面の顕微鏡写真である。FIG. 3 is a photomicrograph of a fracture surface of the diffusion resistance layer in Sample 2. 図４は、サンプル４における拡散抵抗層の破断面の顕微鏡写真である。FIG. 4 is a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 4. 図５は、サンプル５における拡散抵抗層の破断面の顕微鏡写真である。FIG. 5 is a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 5. 図６は、サンプル６における拡散抵抗層の破断面の顕微鏡写真である。FIG. 6 is a photomicrograph of the fracture surface of the diffusion resistance layer in Sample 6.
　以下、本発明を実施した好ましい形態の一例について説明する。但し、下記の実施形態は、単なる例示である。本発明は、下記の実施形態に何ら限定されない。 Hereinafter, an example of a preferable embodiment in which the present invention is implemented will be described. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.
　図１は、本実施形態に係る無機多孔質膜を拡散抵抗層として用いた排気ガスセンサーの要部の模式的断面図である。図１に示されるように、排気ガスセンサー１は、固体電解質層１０を有する。 FIG. 1 is a schematic cross-sectional view of a main part of an exhaust gas sensor using an inorganic porous film according to this embodiment as a diffusion resistance layer. As shown in FIG. 1, the exhaust gas sensor 1 has a solid electrolyte layer 10.
　固体電解質層１０は、例えば、排気ガスに含まれる酸素イオン等に対して導電性を有するセラミックスにより構成することができる。具体的には、固体電解質層１０は、ジルコニア、イットリウム部分安定化ジルコニア等の部分安定化ジルコニア、セリアなどにより構成することができる。ジルコニア、イットリウム部分安定化ジルコニア等の部分安定化ジルコニア、セリアなどにより構成された固体電解質層１０は、例えば５００℃程度の高温に加熱されたときに酸素イオン等に対して導電性を示す。従って、排気ガスセンサー１は、固体電解質層１０が酸素イオン等に対して導電性を示す温度に加熱されて使用される。排気ガスセンサー１は、通常、固体電解質層１０の加熱機構を備えている。 The solid electrolyte layer 10 can be made of, for example, ceramic having conductivity with respect to oxygen ions contained in the exhaust gas. Specifically, the solid electrolyte layer 10 can be composed of partially stabilized zirconia such as zirconia and yttrium partially stabilized zirconia, ceria, and the like. The solid electrolyte layer 10 composed of partially stabilized zirconia such as zirconia or yttrium partially stabilized zirconia, ceria, etc. exhibits conductivity with respect to oxygen ions or the like when heated to a high temperature of about 500 ° C., for example. Therefore, the exhaust gas sensor 1 is used by being heated to a temperature at which the solid electrolyte layer 10 exhibits conductivity with respect to oxygen ions and the like. The exhaust gas sensor 1 usually includes a heating mechanism for the solid electrolyte layer 10.
　固体電解質層１０は、第１の主面１０ａと、第２の主面１０ｂとを有する。第１の主面１０ａの上には、第１の電極１１が設けられている。第２の主面１０ｂの上には、第２の電極１２が設けられている。固体電解質層１０は、第１の電極１１と第２の電極１２とにより挟持されている。 The solid electrolyte layer 10 has a first main surface 10a and a second main surface 10b. A first electrode 11 is provided on the first main surface 10a. A second electrode 12 is provided on the second main surface 10b. The solid electrolyte layer 10 is sandwiched between the first electrode 11 and the second electrode 12.
　第１及び第２の電極１１，１２は、それぞれ、通気性を有する。よって、排気ガスに含まれる酸素等は、第１及び第２の電極１１，１２のそれぞれを厚み方向に通過可能である。第１及び第２の電極１１，１２は、例えば、多孔質膜であってもよいし、メッシュ状に設けられていてもよい。 The first and second electrodes 11 and 12 each have air permeability. Therefore, oxygen contained in the exhaust gas can pass through the first and second electrodes 11 and 12 in the thickness direction. The first and second electrodes 11 and 12 may be, for example, a porous film or may be provided in a mesh shape.
　第１及び第２の電極１１，１２は、それぞれ、Ｐｔ等の触媒活性の高い貴金属により構成することができる。 The first and second electrodes 11 and 12 can each be composed of a noble metal having high catalytic activity such as Pt.
　排気ガスセンサー１は、自動車等の排気経路に配される場合は、第１の電極１１がエンジン側に向き、第２の電極１２が外気側に向くように配される。 When the exhaust gas sensor 1 is disposed in an exhaust path of an automobile or the like, the exhaust gas sensor 1 is disposed such that the first electrode 11 faces the engine side and the second electrode 12 faces the outside air side.
　排気ガスセンサーの一種である酸素センサーにおいては、第１の電極１１側の雰囲気における酸素濃度と、第２の電極１２側の雰囲気における酸素濃度とが異なると、酸素濃度が高い側から酸素濃度が低い側へと酸素イオン流が発生する。これにより、起電力が生じる。この起電力を検出することにより、酸素を検出することができる。なお、排気ガスセンサー１は、酸素センサー以外にも、連続的な空燃比の変化を検出することができる空燃比センサーやＮＯｘ濃度を検出可能なＮＯｘセンサー等に適用することも可能である。 In an oxygen sensor which is a kind of exhaust gas sensor, if the oxygen concentration in the atmosphere on the first electrode 11 side and the oxygen concentration in the atmosphere on the second electrode 12 side are different, the oxygen concentration is increased from the side with the higher oxygen concentration. An oxygen ion stream is generated toward the lower side. Thereby, an electromotive force is generated. By detecting this electromotive force, oxygen can be detected. In addition to the oxygen sensor, the exhaust gas sensor 1 can be applied to an air-fuel ratio sensor that can detect a continuous change in air-fuel ratio, a NO x sensor that can detect NO x concentration, and the like. .
　第１の主面１０ａの上には、第１の電極１１を覆う拡散抵抗層１３が設けられている。拡散抵抗層１３は、固体電解質層１０に供給される排気ガス量を制限する機能を有する層である。 A diffusion resistance layer 13 covering the first electrode 11 is provided on the first main surface 10a. The diffusion resistance layer 13 is a layer having a function of limiting the amount of exhaust gas supplied to the solid electrolyte layer 10.
　拡散抵抗層１３は、連続気泡を有する多孔質体からなる。このため、排気ガスは、拡散抵抗層１３を厚み方向に通過可能である。拡散抵抗層１３の厚みは、所望の排気ガス拡散抵抗能を得るため、５０μｍ～５００μｍであることが好ましく、６０μｍ～３００μｍであることがより好ましく７０μｍ～２００μｍであることがさらに好ましい。 The diffusion resistance layer 13 is made of a porous body having open cells. For this reason, the exhaust gas can pass through the diffusion resistance layer 13 in the thickness direction. The thickness of the diffusion resistance layer 13 is preferably 50 μm to 500 μm, more preferably 60 μm to 300 μm, and even more preferably 70 μm to 200 μm in order to obtain a desired exhaust gas diffusion resistance capability.
　本実施形態では、拡散抵抗層１３は、ガラスと、無機フィラーとを含む。拡散抵抗層１３におけるガラスの含有率は、５０体積％以下である。このため、下記の実験例等の結果からも分かるように、拡散抵抗層１３は、良好な多孔性を有し、かつ、耐熱衝撃性が高い。また、拡散抵抗層１３は、固体電解質層１０との密着性が高い。 In the present embodiment, the diffusion resistance layer 13 includes glass and an inorganic filler. The glass content in the diffusion resistance layer 13 is 50% by volume or less. For this reason, as can be seen from the results of the following experimental examples and the like, the diffusion resistance layer 13 has good porosity and high thermal shock resistance. Further, the diffusion resistance layer 13 has high adhesion with the solid electrolyte layer 10.
　すなわち、拡散抵抗層１３は、ガラスと無機フィラーとを含み、ガラスの含有率が５０体積％以下である無機多孔質膜からなり、耐熱衝撃性が高く、かつ、他の部材に対して高い密着強度を有する。 That is, the diffusion resistance layer 13 is made of an inorganic porous film containing glass and an inorganic filler and having a glass content of 50% by volume or less, and has high thermal shock resistance and high adhesion to other members. Has strength.
　耐熱衝撃性をさらに高め、かつ、固体電解質層１０との密着性をさらに高める観点からは、拡散抵抗層１３は、熱膨張係数が－１０×１０－７／℃～７０×１０－７／℃であることが好ましく、熱膨張係数が－１０×１０－７／℃～３０×１０－７／℃であることがより好ましく、０／℃～１５×１０－７／℃であることがさらに好ましい。拡散抵抗層１３に含まれるガラスは、熱膨張係数が３０×１０－７／℃～１００×１０－７／℃であることが好ましく、４０×１０－７／℃～８０×１０－７／℃であることがより好ましい。拡散抵抗層１３に含まれる無機フィラーは、熱膨張係数が－８０×１０－７／℃～７０×１０－７／℃であることが好ましく、－８０×１０－７／℃～４０×１０－７／℃であることがより好ましく、－１０×１０－７／℃～３０×１０－７／℃であることがさらに好ましい。なお、本発明において、熱膨張係数は、３０℃～３００℃の範囲における線熱膨張係数を意味する。 From the viewpoint of further improving the thermal shock resistance and further improving the adhesion to the solid electrolyte layer 10, the diffusion resistance layer 13 has a thermal expansion coefficient of −10 × 10 −7 / ° C. to 70 × 10 −7 / ° C. The thermal expansion coefficient is preferably −10 × 10 −7 / ° C. to 30 × 10 −7 / ° C., more preferably 0 / ° C. to 15 × 10 −7 / ° C. . The glass contained in the diffusion resistance layer 13 preferably has a thermal expansion coefficient of 30 × 10 −7 / ° C. to 100 × 10 −7 / ° C., and 40 × 10 −7 / ° C. to 80 × 10 −7 / ° C. It is more preferable that The inorganic filler contained in the diffusion resistance layer 13 preferably has a thermal expansion coefficient of −80 × 10 −7 / ° C. to 70 × 10 −7 / ° C., and −80 × 10 −7 / ° C. to 40 × 10 − 7 / ° C. is more preferable, and −10 × 10 −7 / ° C. to 30 × 10 −7 / ° C. is further preferable. In the present invention, the thermal expansion coefficient means a linear thermal expansion coefficient in the range of 30 ° C. to 300 ° C.
　上記のような低い熱膨張係数を有する無機フィラーとしては、例えば、結晶化ガラス、石英ガラス、β－スポジュメン、β－ユークリプタイト、ウイレマイト、コーディエライト、チタン酸アルミニウム、タングステン酸ジルコニウム、リン酸タングステン酸ジルコニウム等が挙げられる。 Examples of the inorganic filler having a low coefficient of thermal expansion as described above include crystallized glass, quartz glass, β-spodumene, β-eucryptite, willemite, cordierite, aluminum titanate, zirconium tungstate, and phosphoric acid. Examples thereof include zirconium tungstate.
　結晶化ガラスの具体例としては、β－スポジュメン固溶体を析出結晶として含有する結晶化ガラス、β－石英固溶体を析出結晶として含有する結晶化ガラス等が挙げられる。結晶化ガラスの結晶化開始温度は７００℃以上であることが好ましく、７５０℃以上であることがより好ましい。結晶化開始温度が低すぎると、拡散抵抗層１３の耐熱性が低下する場合がある。 Specific examples of crystallized glass include crystallized glass containing β-spodumene solid solution as precipitated crystals, crystallized glass containing β-quartz solid solution as precipitated crystals, and the like. The crystallization start temperature of the crystallized glass is preferably 700 ° C. or higher, and more preferably 750 ° C. or higher. If the crystallization start temperature is too low, the heat resistance of the diffusion resistance layer 13 may be reduced.
　拡散抵抗層１３は、１種の無機フィラーを含んでいてもよいし、複数種類の無機フィラーを含んでいてもよい。無機フィラーの融点は、ガラスの軟化温度よりも高いことが好ましい。無機フィラーの平均粒子径（Ｄ５０）は、２μｍ～５０μｍであることが好ましく、３μｍ～１５μｍであることがより好ましい。無機フィラーの平均粒子径（Ｄ５０）が大きすぎると、多孔質体の機械的強度が低い場合や、均一な気孔質体が得られない場合がある。無機フィラーの平均粒子径（Ｄ５０）が小さすぎると、気孔が小さくなりすぎて、排気ガスが通過しにくくなる場合がある。 The diffusion resistance layer 13 may include one type of inorganic filler or may include a plurality of types of inorganic fillers. The melting point of the inorganic filler is preferably higher than the softening temperature of the glass. The average particle diameter (D 50 ) of the inorganic filler is preferably 2 μm to 50 μm, and more preferably 3 μm to 15 μm. If the average particle diameter (D 50 ) of the inorganic filler is too large, the mechanical strength of the porous body may be low, or a uniform porous body may not be obtained. If the average particle diameter (D 50 ) of the inorganic filler is too small, the pores may be too small and the exhaust gas may not pass easily.
　無機フィラーの形状は特に限定されず、例えば略球状、楕球状等が挙げられる。なかでも、無機フィラーが略球状であることにより、拡散抵抗層１３内部の気孔の分布が均一になりやすく、結果として排気ガスの通気性が安定しやすくなる。 The shape of the inorganic filler is not particularly limited, and examples thereof include a substantially spherical shape and an elliptical shape. Especially, when the inorganic filler is substantially spherical, the distribution of pores inside the diffusion resistance layer 13 is likely to be uniform, and as a result, the air permeability of the exhaust gas is easily stabilized.
　本明細書において、ガラスの軟化温度は、ＤＴＡ（示差熱分析装置）により測定した値をいう。 In this specification, the softening temperature of glass refers to a value measured with a DTA (differential thermal analyzer).
　無機フィラーの平均粒子径（Ｄ５０）に対する９９％粒子径（Ｄ９９）の比（Ｄ９９／Ｄ５０）は、３以上であることが好ましく、５以上であることがさらに好ましい。そうすることにより、拡散抵抗層１３の耐熱衝撃性を高めることができる。但し、Ｄ９９／Ｄ５０が高すぎると多孔質体の機械的強度が低くなる場合がある。従って、Ｄ９９／Ｄ５０は、１００以下であることが好ましく、３０以下であることがより好ましい。 The ratio of the 99% particle diameter to the average particle diameter of the inorganic filler (D 50) (D 99) (D 99 / D 50) is preferably 3 or more, further preferably 5 or more. By doing so, the thermal shock resistance of the diffusion resistance layer 13 can be improved. However, if D 99 / D 50 is too high, the mechanical strength of the porous body may be lowered. Therefore, D 99 / D 50 is preferably 100 or less, and more preferably 30 or less.
　本発明において、平均粒子径（Ｄ５０）及び９９％粒子径（Ｄ９９）は、レーザー回折式粒度分布計により測定することができる。 In the present invention, the average particle size (D 50 ) and the 99% particle size (D 99 ) can be measured with a laser diffraction particle size distribution meter.
　なお、拡散抵抗層１３と固体電解質層１０との密着性を高める観点からは、拡散抵抗層１３におけるガラスの含有率が高い方が好ましい。このため、拡散抵抗層１３におけるガラスの含有率は、３体積％以上であることが好ましく、５体積％以上であることがより好ましい。しかしながら、拡散抵抗層１３におけるガラスの含有率が高すぎると、拡散抵抗層１３の耐熱衝撃性が低下したり、気孔率が低くなりすぎる場合がある。従って、拡散抵抗層１３におけるガラスの含有率は、５０体積％以下である必要があり、３０体積％以下であることが好ましく、２０体積％以下であることがさらに好ましい。 In addition, from the viewpoint of improving the adhesion between the diffusion resistance layer 13 and the solid electrolyte layer 10, it is preferable that the glass content in the diffusion resistance layer 13 is higher. For this reason, the glass content in the diffusion resistance layer 13 is preferably 3% by volume or more, and more preferably 5% by volume or more. However, if the glass content in the diffusion resistance layer 13 is too high, the thermal shock resistance of the diffusion resistance layer 13 may decrease or the porosity may become too low. Accordingly, the glass content in the diffusion resistance layer 13 needs to be 50% by volume or less, preferably 30% by volume or less, and more preferably 20% by volume or less.
　拡散抵抗層１３の気孔率は、拡散抵抗層１３に求められる特性等に応じて適宜設定することができる。拡散抵抗層１３の気孔率は、例えば、２０％～８０％であることが好ましく、３０％～７０％であることがより好ましい。 The porosity of the diffusion resistance layer 13 can be appropriately set according to characteristics required for the diffusion resistance layer 13. For example, the porosity of the diffusion resistance layer 13 is preferably 20% to 80%, and more preferably 30% to 70%.
　拡散抵抗層１３に含まれるガラスの軟化温度は、１１００℃以下であることが好ましく、１０００℃以下であることがより好ましい。拡散抵抗層１３に含まれるガラスの軟化温度が高すぎると、焼成時に無機フィラーが変質する場合がある。拡散抵抗層１３に含まれるガラスの軟化温度の下限は特に限定されないが、排気ガスセンサーの使用環境下における軟化変形を抑制する、すなわち耐熱性を向上させるため、４００℃以上であることが好ましく、５００℃以上であることがより好ましく、６００℃以上であることがさらに好ましく、７００℃以上であることが特に好ましく、８００℃以上であることが最も好ましい。 The softening temperature of the glass contained in the diffusion resistance layer 13 is preferably 1100 ° C. or less, and more preferably 1000 ° C. or less. If the softening temperature of the glass contained in the diffusion resistance layer 13 is too high, the inorganic filler may be altered during firing. The lower limit of the softening temperature of the glass contained in the diffusion resistance layer 13 is not particularly limited, but is preferably 400 ° C. or higher in order to suppress softening deformation under the use environment of the exhaust gas sensor, that is, to improve heat resistance. It is more preferably 500 ° C. or higher, further preferably 600 ° C. or higher, particularly preferably 700 ° C. or higher, and most preferably 800 ° C. or higher.
　拡散抵抗層１３に含まれるガラスとしては、耐熱性の観点から、シリカホウ酸系ガラスであることが好ましい。シリカホウ酸系ガラスの具体例としては、質量％で、ＳｉＯ２　２５～７０％、Ｂ２Ｏ３　１～５０％、ＭｇＯ　０～１０％、ＣａＯ　０～２５％、ＳｒＯ　０～１０％、ＢａＯ　０～４０％、ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ　１０～４５％、Ａｌ２Ｏ３　０～２０％、及びＺｎＯ　０～２５％含有するものが挙げられる。さらには、質量％で、ＳｉＯ２　３０～７０％、Ｂ２Ｏ３　１～１５％、ＭｇＯ　０～１０％、ＣａＯ　０～２５％、ＳｒＯ　０～１０％、ＢａＯ　０～４０％、ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ　１０～４５％、Ａｌ２Ｏ３　０～２０％、及びＺｎＯ　０～１０％含有するものが好ましい。なお、アルカリ金属成分（Ｌｉ２Ｏ、Ｎａ２Ｏ及びＫ２Ｏ）は軟化温度を低下させるため、その含有量が多すぎると拡散抵抗層１３の耐熱性が低下する場合がある。よって、アルカリ金属成分の含有量は、合量で１０％以下であることが好ましく、５％以下であることがより好ましく、１％以下であることがさらに好ましく、含有しないことが特に好ましい。 The glass contained in the diffusion resistance layer 13 is preferably a silica borate glass from the viewpoint of heat resistance. Specific examples of the silica borate glass include, by mass%, SiO 2 25 to 70%, B 2 O 3 1 to 50%, MgO 0 to 10%, CaO 0 to 25%, SrO 0 to 10%, BaO 0. -40%, MgO + CaO + SrO + BaO 10-45%, Al 2 O 3 0-20%, and ZnO 0-25%. Further, by mass%, SiO 2 30 to 70%, B 2 O 3 1 to 15%, MgO 0 to 10%, CaO 0 to 25%, SrO 0 to 10%, BaO 0 to 40%, MgO + CaO + SrO + BaO 10 to Those containing 45%, Al 2 O 3 0-20% and ZnO 0-10% are preferred. Since the alkali metal component (Li 2 O, Na 2 O and K 2 O) is to lower the softening temperature, and its content is too large, the heat resistance of the diffusion resistance layer 13 may be lowered. Therefore, the total content of alkali metal components is preferably 10% or less, more preferably 5% or less, further preferably 1% or less, and particularly preferably not contained.
　なお、本実施形態では、第１の主面１０ａの上にのみ拡散抵抗層１３が設けられている例について説明した。但し、本発明は、この構成に限定されない。例えば、第１の主面１０ａと第２の主面１０ｂとのそれぞれの上に拡散抵抗層１３が設けられていてもよい。 In the present embodiment, the example in which the diffusion resistance layer 13 is provided only on the first main surface 10a has been described. However, the present invention is not limited to this configuration. For example, the diffusion resistance layer 13 may be provided on each of the first main surface 10a and the second main surface 10b.
　排気ガスセンサー１は、例えば以下の要領で製造することができる。なお、ここでは、排気ガスセンサー１の要部の製造方法についてのみ説明する。その他の部分の製造方法は、例えば、従来の方法と同様としてもよい。 The exhaust gas sensor 1 can be manufactured, for example, in the following manner. Here, only the manufacturing method of the main part of the exhaust gas sensor 1 will be described. The manufacturing method of other parts may be the same as the conventional method, for example.
　まず、固体電解質層１０を用意する。次に、固体電解質層１０の上に、第１の電極１１と第２の電極１２とを形成する。第１及び第２の電極１１，１２の形成方法は、特に限定されない。第１及び第２の電極１１，１２は、例えば、スパッタリング法、蒸着法、メッキ法等により形成することができる。 First, the solid electrolyte layer 10 is prepared. Next, the first electrode 11 and the second electrode 12 are formed on the solid electrolyte layer 10. The formation method of the 1st and 2nd electrodes 11 and 12 is not specifically limited. The first and second electrodes 11 and 12 can be formed, for example, by sputtering, vapor deposition, plating, or the like.
　次に、第１の主面１０ａの上に、第１の電極１１を覆うように拡散抵抗層１３を形成する。具体的には、まず、ガラス粉末と、無機フィラーとを含むペーストを準備する。ペーストは、ガラス粉末及び無機フィラーに加え、樹脂バインダーや、溶剤等を含んでいてもよい。なお、ペースト中に繊維状の結晶性セルロースを添加することにより、拡散抵抗層１３の気孔率を高める（気孔径を大きくする）ことができる。次に、ペーストを第１の主面１０ａの上に、第１の電極１１を覆うように塗布し、乾燥させることにより、ペースト層を形成する（ペースト法）。その後、ペースト層を焼成することにより、拡散抵抗層１３を形成することができる。なお、ペースト層の焼成の前に、樹脂バインダーや溶剤等を除去する脱脂工程を行ってもよい。 Next, a diffusion resistance layer 13 is formed on the first main surface 10a so as to cover the first electrode 11. Specifically, first, a paste containing glass powder and an inorganic filler is prepared. The paste may contain a resin binder, a solvent and the like in addition to the glass powder and the inorganic filler. In addition, the porosity of the diffusion resistance layer 13 can be increased (the pore diameter is increased) by adding fibrous crystalline cellulose to the paste. Next, the paste is applied on the first main surface 10a so as to cover the first electrode 11, and dried to form a paste layer (paste method). Thereafter, the diffusion resistance layer 13 can be formed by firing the paste layer. In addition, you may perform the degreasing process which removes a resin binder, a solvent, etc. before baking of a paste layer.
　ペースト層の焼成は、ガラスの軟化温度～ガラスの軟化温度＋４００℃の範囲内で行うことが好ましく、ガラスの軟化温度＋５０℃～ガラスの軟化温度＋２５０℃の範囲内で行うことがより好ましく、ガラスの軟化温度＋５０℃～ガラスの軟化温度＋２００℃の範囲内で行うことがさらに好ましい。ペースト層の焼成温度が高すぎると、得られる拡散抵抗層１３が好適な多孔質体とならない場合がある。一方、ペースト層の焼成温度が低すぎると、十分に焼成が進まず、得られる拡散抵抗層１３の耐熱衝撃性が低くなったり、拡散抵抗層１３と固体電解質層１０との密着性が低くなったりする場合がある。 The firing of the paste layer is preferably performed within the range of the glass softening temperature to the glass softening temperature + 400 ° C., more preferably within the range of the glass softening temperature + 50 ° C. to the glass softening temperature + 250 ° C. It is more preferable to carry out within the range of the softening temperature of the glass + 50 ° C. to the softening temperature of the glass + 200 ° C. If the firing temperature of the paste layer is too high, the resulting diffusion resistance layer 13 may not be a suitable porous body. On the other hand, if the firing temperature of the paste layer is too low, the firing does not proceed sufficiently and the thermal shock resistance of the obtained diffusion resistance layer 13 is lowered, or the adhesion between the diffusion resistance layer 13 and the solid electrolyte layer 10 is lowered. Sometimes.
　ガラス粉末の平均粒子径（Ｄ５０）は、０．５μｍ～２０μｍであることが好ましく、２μｍ～１０μｍであることがより好ましい。ガラス粉末の平均粒子径（Ｄ５０）が大きすぎると、均一な多孔質体が得られない場合がある。ガラス粉末の平均粒子径（Ｄ５０）が小さすぎると、多孔質体の強度に劣る場合がある。 The average particle diameter (D 50 ) of the glass powder is preferably 0.5 μm to 20 μm, and more preferably 2 μm to 10 μm. If the average particle diameter (D 50 ) of the glass powder is too large, a uniform porous body may not be obtained. If the average particle diameter (D 50 ) of the glass powder is too small, the strength of the porous body may be inferior.
　ガラス粉末の平均粒子径（Ｄ５０）は、無機フィラーの平均粒子径（Ｄ５０）よりも小さいことが好ましい。すなわち、ガラス粉末の平均粒子径（Ｄ５０）に対する無機フィラーの平均粒子径（Ｄ５０）の比（無機フィラーの平均粒子径（Ｄ５０）／ガラス粉末の平均粒子径（Ｄ５０））が１より大きいことが好ましい。（無機フィラーの平均粒子径（Ｄ５０）／ガラス粉末の平均粒子径（Ｄ５０））は、３以上であることがより好ましく、１０以上であることがさらに好ましい。（無機フィラーの平均粒子径（Ｄ５０）／ガラス粉末の平均粒子径（Ｄ５０））を小さくすることにより、無機フィラーの周囲に形成されるガラス壁の厚みを薄くでき、拡散抵抗層１３を好適な多孔質体とすることができる。但し、（無機フィラーの平均粒子径（Ｄ５０）／ガラス粉末の平均粒子径（Ｄ５０））が大きすぎると、多孔質体の強度が低下する場合がある。従って、（無機フィラーの平均粒子径（Ｄ５０）／ガラス粉末の平均粒子径（Ｄ５０））は、５０以下であることが好ましく、３０以下であることがより好ましい。 The average particle diameter of the glass powder (D 50) is smaller than the average particle diameter of the inorganic filler (D 50) are preferred. That is, the ratio of the average particle diameter of the inorganic filler to the average particle diameter of the glass powder (D 50) (D 50) (average particle diameter of the inorganic filler (D 50) / average particle diameter (D 50 of the glass powder)) is 1 Larger is preferred. The average particle diameter of the inorganic filler (D 50 ) / average particle diameter of the glass powder (D 50 ) is more preferably 3 or more, and even more preferably 10 or more. By reducing (average particle diameter of inorganic filler (D 50 ) / average particle diameter of glass powder (D 50 )), the thickness of the glass wall formed around the inorganic filler can be reduced, and the diffusion resistance layer 13 can be reduced. It can be set as a suitable porous body. However, if the (average particle diameter of the inorganic filler (D 50 ) / average particle diameter of the glass powder (D 50 )) is too large, the strength of the porous body may decrease. Therefore, (average particle diameter of inorganic filler (D 50 ) / average particle diameter of glass powder (D 50 )) is preferably 50 or less, and more preferably 30 or less.
　なお、本実施形態では、まず固体電解質層１０を用意した後に、固体電解質層１０の上に拡散抵抗層１３作製用ペースト層の焼成を行う例について説明したが、拡散抵抗層１３を形成するためのペースト層と、固体電解質層１０を形成するためのペースト層を積層して同時焼成してもよい。また、ペースト法以外にも、スプレー法やディッピング法等により、固体電解質層１０や拡散抵抗層１３を形成してもよい。 In the present embodiment, the example in which the solid electrolyte layer 10 is first prepared and then the paste layer for forming the diffusion resistance layer 13 is fired on the solid electrolyte layer 10 has been described. However, in order to form the diffusion resistance layer 13. These paste layers and a paste layer for forming the solid electrolyte layer 10 may be laminated and fired simultaneously. In addition to the paste method, the solid electrolyte layer 10 and the diffusion resistance layer 13 may be formed by a spray method, a dipping method, or the like.
　以下、本発明について、具体的な実験例に基づいて、さらに詳細に説明するが、本発明は以下の実験例に何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能である。 Hereinafter, the present invention will be described in more detail on the basis of specific experimental examples. However, the present invention is not limited to the following experimental examples, and may be appropriately modified and implemented without departing from the scope of the present invention. Is possible.
　（実験例１）
　ガラス粉末（日本電気硝子株式会社製シリカホウ酸系ガラスＧＡ－４、平均粒子径（Ｄ５０）：２．９μｍ、９９％粒子径（Ｄ９９）：１０μｍ、軟化温度：６２５℃、熱膨張係数：６４×１０－７／℃）と、結晶化ガラス粉末（日本電気硝子株式会社製β－石英固溶体析出結晶化ガラス、結晶化開始温度：８７０℃、平均粒子径（Ｄ５０）：７．３μｍ、９９％粒子径（Ｄ９９）：８７μｍ、熱膨張係数：－７×１０－７／℃）と、樹脂バインダー（エチルセルロース）、有機溶剤（ターピネオール及びブチルカルビトールアセテート）を混練し、ペーストを作製した。なお、ガラス粉末の含有率（｛（ガラス粉末の体積含有量）／（ガラス粉末の体積含有量＋結晶化ガラス粉末の体積含有量）｝×１００）を５体積％とした。 (Experimental example 1)
Glass powder (silica borate glass GA-4 manufactured by Nippon Electric Glass Co., Ltd., average particle size (D 50 ): 2.9 μm, 99% particle size (D 99 ): 10 μm, softening temperature: 625 ° C., thermal expansion coefficient: 64 × 10 −7 / ° C.) and crystallized glass powder (β-quartz solid solution precipitated crystallized glass manufactured by Nippon Electric Glass Co., Ltd., crystallization start temperature: 870 ° C., average particle diameter (D 50 ): 7.3 μm, 99% particle size (D 99 ): 87 μm, coefficient of thermal expansion: −7 × 10 −7 / ° C.), resin binder (ethyl cellulose), organic solvent (terpineol and butyl carbitol acetate) were kneaded to prepare a paste. . The content of glass powder ({(volume content of glass powder) / (volume content of glass powder + volume content of crystallized glass powder)} × 100) was 5% by volume.
　ジルコニア基板の上に、塗布厚が２００μｍとなるように塗布し、ペースト層を形成した。ジルコニア基板としては、アズワン社製の緻密質ジルコニア（５０ｍｍ×５０ｍｍ×２ｍｍのサイズのものを４分割して２５ｍｍ×２５ｍｍ×２ｍｍとしたもの）の表面をダイヤモンド＃１０００電着研磨盤で研磨したものを使用した。その後、ペースト層を８５０℃で１０分間焼成することにより、サンプル１を作製した。サンプル１における拡散抵抗層の破断面の顕微鏡写真を図２に示す。 A paste layer was formed on a zirconia substrate so that the coating thickness was 200 μm. As a zirconia substrate, the surface of a dense zirconia manufactured by AS ONE (50 mm × 50 mm × 2 mm size divided into 4 × 25 mm × 25 mm × 2 mm) was polished with a diamond # 1000 electrodeposition polishing machine It was used. Thereafter, the paste layer was baked at 850 ° C. for 10 minutes to prepare Sample 1. A photomicrograph of the fracture surface of the diffusion resistance layer in Sample 1 is shown in FIG.
　なお、気孔率は、ガラス粉末と結晶化ガラス粉末の密度から理論密度を求め、試料の体積と質量から見かけ密度を求め、理論密度と見かけ密度から算出した。また、拡散抵抗層の熱膨張係数は次のようにして測定した。ステンレス金型に原料粉末を入れ、プレス成型後、上記の温度と時間で熱処理を行って焼結体を得た。得られた焼結体を直径５ｍｍ、長さ２０ｍｍ程度に加工して測定用試料を作製した。測定用試料について、熱機械分析装置を用いて熱膨張係数を測定した。測定条件は、昇温速度１０℃／分、温度範囲３０℃～３００℃とした。 Note that the porosity was calculated from the theoretical density and the apparent density by calculating the theoretical density from the density of the glass powder and the crystallized glass powder, determining the apparent density from the volume and mass of the sample. The thermal expansion coefficient of the diffusion resistance layer was measured as follows. Raw material powder was put into a stainless steel mold, and after press molding, heat treatment was performed at the above temperature and time to obtain a sintered body. The obtained sintered body was processed into a diameter of about 5 mm and a length of about 20 mm to prepare a measurement sample. About the sample for a measurement, the thermal expansion coefficient was measured using the thermomechanical analyzer. The measurement conditions were a temperature increase rate of 10 ° C./min and a temperature range of 30 ° C. to 300 ° C.
　（実験例２）
　ガラス粉末の含有率を１０体積％としたこと以外は、実験例１と同様にしてサンプル２を作製した。サンプル２における拡散抵抗層の破断面の顕微鏡写真を図３に示す。 (Experimental example 2)
Sample 2 was produced in the same manner as in Experimental Example 1, except that the glass powder content was 10% by volume. A photomicrograph of the fracture surface of the diffusion resistance layer in Sample 2 is shown in FIG.
　（実験例３）
　ペースト層の焼成温度を８００℃としたこと以外は、実験例１と同様にしてサンプル３を作製した。 (Experimental example 3)
Sample 3 was produced in the same manner as in Experimental Example 1 except that the firing temperature of the paste layer was 800 ° C.
　（実験例４）
　ペースト層の焼成温度を８００℃としたこと以外は、実験例２と同様にしてサンプル４を作製した。サンプル４における拡散抵抗層の破断面の顕微鏡写真を図４に示す。 (Experimental example 4)
Sample 4 was produced in the same manner as in Experimental Example 2, except that the firing temperature of the paste layer was 800 ° C. A photomicrograph of the fracture surface of the diffusion resistance layer in Sample 4 is shown in FIG.
　（実験例５）
　ガラス粉末の含有率を２０体積％とし、ペースト層の焼成温度を８００℃としたこと以外は、実験例１と同様にしてサンプル５を作製した。サンプル５における拡散抵抗層の破断面の顕微鏡写真を図５に示す。 (Experimental example 5)
Sample 5 was produced in the same manner as in Experimental Example 1, except that the glass powder content was 20% by volume and the paste layer was fired at 800 ° C. A micrograph of the fracture surface of the diffusion resistance layer in Sample 5 is shown in FIG.
　（実験例６）
　結晶化ガラス粉末の代わりに、アルミナ粉末（フジミインコーポレーテッド社製ＦＯ－１０００、平均粒子径（Ｄ５０）：１２．７μｍ、９９％粒子径（Ｄ９９）：２３μｍ、熱膨張係数：６０～７０×１０－７／℃）を用い、ガラス粉末の含有率（｛（ガラス粉末の体積含有量）／（ガラス粉末の体積含有量＋アルミナ粉末の体積含有量）｝×１００）を３０体積％としたこと以外は、実験例１と同様にしてサンプル６を作製した。サンプル６における拡散抵抗層の破断面の顕微鏡写真を図６に示す。 (Experimental example 6)
Instead of crystallized glass powder, alumina powder (FO-1000 manufactured by Fujimi Incorporated, average particle size (D 50 ): 12.7 μm, 99% particle size (D 99 ): 23 μm, thermal expansion coefficient: 60 to 70 × 10 −7 / ° C.), and the content of glass powder ({(volume content of glass powder) / (volume content of glass powder + volume content of alumina powder)} × 100) is 30% by volume. A sample 6 was produced in the same manner as in Experimental Example 1 except for the above. A micrograph of the fracture surface of the diffusion resistance layer in Sample 6 is shown in FIG.
　（実験例７）
　ガラス粉末を用いず、アルミナ粉末のみを用いたこと以外は、実験例６と同様にしてサンプル７を作製した。 (Experimental example 7)
Sample 7 was produced in the same manner as in Experimental Example 6 except that only the alumina powder was used without using the glass powder.
　（耐熱衝撃性の評価）
　実験例１～７において作製したサンプル１～７のそれぞれを５００℃に加熱し、その上に水を滴下した。室温まで冷却後、上記と同様の密着強度評価を実施し、膜が全く剥がれなかった場合を「◎」とし、一部しか剥がれなかった場合を、「○」とし、半分以上剥がれた場合を「△」、完全に剥がれた場合またはクラックが入った場合を「×」とした。結果を表１に示す。 (Evaluation of thermal shock resistance)
Each of Samples 1 to 7 prepared in Experimental Examples 1 to 7 was heated to 500 ° C., and water was dropped thereon. After cooling to room temperature, the same adhesion strength evaluation as described above was performed.If the film was not peeled off at all, `` ◎ '', if only a part was peeled off, `` ○ '', if it was peeled off more than half “△”, “x” when completely peeled off or cracked. The results are shown in Table 1.
　（密着強度評価）
　実験例１～７において作製したサンプル１～７のそれぞれについて、１００ｍｍの高さから木製の板の上に１０回落下をすることにより密着強度を評価した。膜が剥がれなかった場合を、「◎」とし、一部しか剥がれなかった場合を、「○」とし、半分以上剥がれた場合を「△」、完全に剥がれた場合を「×」とした。結果を表１に示す。 (Adhesion strength evaluation)
For each of Samples 1 to 7 produced in Experimental Examples 1 to 7, the adhesion strength was evaluated by dropping 10 times onto a wooden plate from a height of 100 mm. The case where the film was not peeled off was designated as “◎”, the case where only a part was peeled off was designated as “◯”, the case where half or more was peeled off was designated as “Δ”, and the case where the film was completely peeled off was designated as “X”. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
 　（実験例８）
　ガラス粉末として、日本電気硝子株式会社製シリカホウ酸系ガラスＧＡ－１３（平均粒子径（Ｄ５０）：２．３μｍ、９９％粒子径（Ｄ９９）：６．８μｍ、軟化温度：８４８℃、熱膨張係数：６４．９×１０－７／℃）を用い、ガラス粉末の含有率を８体積％、ペースト層の焼成温度を９３０℃としたこと以外は、実験例１と同様にしてサンプル８を作製した。
Figure JPOXMLDOC01-appb-T000001
 (Experimental example 8)
As glass powder, silica borate glass GA-13 manufactured by Nippon Electric Glass Co., Ltd. (average particle size (D 50 ): 2.3 μm, 99% particle size (D 99 ): 6.8 μm, softening temperature: 848 ° C., heat Sample 8 was prepared in the same manner as in Experimental Example 1, except that the coefficient of expansion was 64.9 × 10 −7 / ° C., the glass powder content was 8% by volume, and the paste layer firing temperature was 930 ° C. Produced.
　（実験例９）
　ガラス粉末の含有率を１０体積％、ペースト層の焼成温度を９００℃としたこと以外は、実験例８と同様にしてサンプル９を作製した。 (Experimental example 9)
Sample 9 was prepared in the same manner as in Experimental Example 8, except that the glass powder content was 10% by volume and the paste layer firing temperature was 900 ° C.
　（実験例１０）
　ガラス粉末の含有率を５５体積％、ペースト層の焼成温度を９００℃としたこと以外は、実験例８と同様にしてサンプル１０を作製した。 (Experimental example 10)
Sample 10 was produced in the same manner as in Experimental Example 8, except that the glass powder content was 55% by volume and the paste layer firing temperature was 900 ° C.
　サンプル８～１０について、上記の方法で耐熱衝撃性を評価したところ、表２に示す通り、サンプル８及び９は◎、サンプル１０は×の評価であった。サンプル８及び９について、さらに密着強度を測定したところ、◎の評価であった。 When the thermal shock resistance of samples 8 to 10 was evaluated by the above method, as shown in Table 2, samples 8 and 9 were evaluated as ◎, and sample 10 was evaluated as ×. Samples 8 and 9 were further evaluated for adhesion when the adhesion strength was measured.
Figure JPOXMLDOC01-appb-T000002
 　（耐熱性の評価）
　サンプル２及び９における拡散抵抗層の耐熱性を評価するため、以下の試験を行った。実験例２及び９で用いたガラス粉末と、結晶化ガラス粉末を、ガラス粉末の含有率が１０体積％となるように混合した。得られた混合粉末を、φ２０ｍｍの金型に理論密度に相当する分量を充填し、プレス成形を行うことにより円柱状の予備成型体を得た。予備成型体を表３に記載の温度で１０分間焼成し、得られた円柱状焼結体の上下面を＃１０００の耐水研磨紙で研磨することにより円柱状のサンプル２’及び９’を得た。
Figure JPOXMLDOC01-appb-T000002
 (Evaluation of heat resistance)
In order to evaluate the heat resistance of the diffusion resistance layers in Samples 2 and 9, the following tests were performed. The glass powder used in Experimental Examples 2 and 9 and the crystallized glass powder were mixed so that the glass powder content was 10% by volume. The obtained mixed powder was filled in a φ20 mm mold with an amount corresponding to the theoretical density, and press-molded to obtain a cylindrical preform. The preforms were fired at the temperatures shown in Table 3 for 10 minutes, and the cylindrical sintered bodies 2 ′ and 9 ′ were obtained by polishing the upper and lower surfaces of the obtained cylindrical sintered body with # 1000 water-resistant abrasive paper. It was.
　得られたサンプル２’及び９’を７５０℃で２４時間熱処理し、熱処理前に対する熱処理後の直径及び高さの変化率を下記の式により求めた。 The obtained samples 2 'and 9' were heat-treated at 750 ° C for 24 hours, and the change rate of the diameter and height after the heat treatment before the heat treatment was obtained by the following formula.
　　直径の変化率＝｛（熱処理後の直径－熱処理前の直径）／熱処理前の直径｝×１００（％）
　　高さの変化率＝｛（熱処理後の高さ－熱処理前の高さ）／熱処理前の直径｝×１００（％） Diameter change rate = {(diameter after heat treatment−diameter before heat treatment) / diameter before heat treatment} × 100 (%)
Change rate of height = {(height after heat treatment−height before heat treatment) / diameter before heat treatment} × 100 (%)
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
１：排気ガスセンサー
１０：固体電解質層
１０ａ：固体電解質層の第１の主面
１０ｂ：固体電解質層の第２の主面
１１：第１の電極
１２：第２の電極
１３：拡散抵抗層 1: exhaust gas sensor 10: solid electrolyte layer 10a: first main surface 10b of solid electrolyte layer: second main surface 11 of solid electrolyte layer 11: first electrode 12: second electrode 13: diffusion resistance layer

Claims (18)

  1. 　ガラスと、無機フィラーとを含み、ガラスの含有率が５０体積％以下である、無機多孔質膜。 An inorganic porous membrane containing glass and an inorganic filler and having a glass content of 50% by volume or less.
  2. 　前記無機フィラーが、結晶化ガラス、石英ガラス、β－スポジュメン、β－ユークリプタイト、ウイレマイト、コーディエライト、チタン酸アルミニウム、タングステン酸ジルコニウム及びリンタングステン酸ジルコニウムからなる群から選ばれた少なくとも一種からなる、請求項１に記載の無機多孔質膜。 The inorganic filler is at least one selected from the group consisting of crystallized glass, quartz glass, β-spodumene, β-eucryptite, willemite, cordierite, aluminum titanate, zirconium tungstate and zirconium phosphotungstate. The inorganic porous membrane according to claim 1.
  3. 　前記無機フィラーが、β－スポジュメン固溶体またはβ－石英固溶体を析出結晶として含有する結晶化ガラスからなる、請求項１に記載の無機多孔質膜。 2. The inorganic porous membrane according to claim 1, wherein the inorganic filler is made of crystallized glass containing a β-spodumene solid solution or a β-quartz solid solution as a precipitated crystal.
  4. 　前記ガラスが、シリカホウ酸系ガラスである、請求項１～３のいずれか一項に記載の無機多孔質膜。 The inorganic porous film according to any one of claims 1 to 3, wherein the glass is silica borate glass.
  5. 　前記シリカホウ酸系ガラスが、質量％で、ＳｉＯ２　２５～７０％、Ｂ２Ｏ３　１～５０％、ＭｇＯ　０～１０％、ＣａＯ　０～２５％、ＳｒＯ　０～１０％、ＢａＯ　０～４０％、ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ　１０～４５％、Ａｌ２Ｏ３　０～２０％、及びＺｎＯ　０～２５％含有する、請求項４に記載の無機多孔質膜。 The silica borate glass is, by mass%, SiO 2 25-70%, B 2 O 3 1-50%, MgO 0-10%, CaO 0-25%, SrO 0-10%, BaO 0-40%. The inorganic porous film according to claim 4, wherein MgO + CaO + SrO + BaO is contained in an amount of 10 to 45%, Al 2 O 3 0 to 20%, and ZnO 0 to 25%.
  6. 　前記シリカホウ酸系ガラスにおけるアルカリ金属成分の含有量の合量が、質量％で１０％以下である、請求項４または５に記載の無機多孔質膜。 The inorganic porous membrane according to claim 4 or 5, wherein the total content of alkali metal components in the silica borate glass is 10% by mass or less.
  7. 　熱膨張係数が７０×１０－７／℃以下である、請求項１～６のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 6, having a thermal expansion coefficient of 70 × 10 -7 / ° C or less.
  8. 　前記ガラスの熱膨張係数が１００×１０－７／℃以下である、請求項１～７のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 7, wherein the glass has a thermal expansion coefficient of 100 × 10 -7 / ° C or less.
  9. 　前記無機フィラーの熱膨張係数が７０×１０－７／℃以下である、請求項１～８のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 8, wherein the inorganic filler has a thermal expansion coefficient of 70 × 10 -7 / ° C or less.
  10. 　前記ガラスの軟化温度が４００℃～１１００℃である、請求項１～９のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 9, wherein the softening temperature of the glass is 400 ° C to 1100 ° C.
  11. 　前記無機フィラーの平均粒子径（Ｄ５０）が２μｍ～５０μｍである、請求項１～１０のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 10, wherein the inorganic filler has an average particle size (D 50 ) of 2 to 50 µm.
  12. 　前記無機フィラーの平均粒子径（Ｄ５０）に対する９９％粒子径（Ｄ９９）の比（Ｄ９９／Ｄ５０）が３～１００である、請求項１～１１のいずれか一項に記載の無機多孔質膜。 The ratio of the average 99% particle diameter to the particle diameter (D 50) of the inorganic filler (D 99) (D 99 / D 50) is 3 to 100, according to one of claims 1 to 11 inorganic Porous membrane.
  13. 　気孔率が２０％～８０％である、請求項１～１２のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 12, which has a porosity of 20% to 80%.
  14. 　排気ガスセンサーの拡散抵抗層に用いられる、請求項１～１３のいずれか一項に記載の無機多孔質膜。 The inorganic porous membrane according to any one of claims 1 to 13, which is used for a diffusion resistance layer of an exhaust gas sensor.
  15. 　請求項１～１４のいずれか一項に記載の無機多孔質膜の製造方法であって、
    　ガラス粉末と前記無機フィラーとを含むペーストからなるペースト層を焼成する、無機多孔質膜の製造方法。     A method for producing an inorganic porous membrane according to any one of claims 1 to 14,
    The manufacturing method of an inorganic porous film | membrane which bakes the paste layer which consists of a paste containing glass powder and the said inorganic filler.
  16. 　前記ガラスの軟化温度～前記ガラスの軟化温度＋４００℃の温度で前記ペースト層を焼成する、請求項１５に記載の無機多孔質膜の製造方法。 16. The method for producing an inorganic porous film according to claim 15, wherein the paste layer is baked at a temperature of the glass softening temperature to the glass softening temperature + 400 ° C.
  17. 　前記ガラス粉末の平均粒子径（Ｄ５０）が０．５μｍ～２０μｍである、請求項１５又は１６に記載の無機多孔質膜の製造方法。 The method for producing an inorganic porous membrane according to claim 15 or 16, wherein the glass powder has an average particle size (D 50 ) of 0.5 µm to 20 µm.
  18. 　前記ガラス粉末の平均粒子径（Ｄ５０）が、前記無機フィラーの平均粒子径（Ｄ５０）よりも小さい、請求項１５～１７のいずれか一項に記載の無機多孔質膜の製造方法。 The average particle diameter of the glass powder (D 50) is the average particle diameter of the inorganic filler (D 50) less than, the production method of the inorganic porous membrane according to any one of claims 15-17.
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