Aluminum titanate-mullite base ceramics
First Claim
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1. A sintered aluminum titanate-mullite base ceramic consisting essentially of:
- a chemical composition of not greater than 0.8% of MgO, 53 to 74% of Al2 O3, 14 to 33% of TiO2, 1.2 to 5% of Fe2 O3, 6 to 20% of SiO2, and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, and an amount of glass in mullite base matrices of the sintered ceramic being not greater than 5% when measured at a section of a body of said sintered ceramic;
said sintered aluminum titanate-mullite base ceramic being formed by compounding 40 to 65% of a raw material of aluminum titanate consisting essentially of 45 to 62% of Al2 O3, 34 to 50% of TiO2, 3 to 7% of Fe2 O3, not greater than 1% of SiO2 and (CaO+Na1 O+K2 O) in an amount not greater than 0.3%, with 35 to 60% of a raw material of mullite consisting essentially of 18 to 32% of SiO2, 68 to 82% of Al2 O3, and (Fe2 O3 +TiO2 +CaO+MgO+Na2 O+K2 O) in an amount not greater than 0.8%, at least one of said aluminum titanate raw material and said mullite raw material being preliminarily fired at a temperature which is not less than 1550°
C., molding a resulting mixture of the raw materials, and subsequently firing a thus obtained molding at 1,550°
to 1,700°
C. in an oxidizing atmosphere resulting in a sintered aluminum titanate-mullite base ceramic article;
said article having an average coefficient of thermal expansion at a temperature range of 40°
to 800°
C. of -2.0×
10-6 /°
C. to 2.0×
10-6 /°
C.;
said article having an increment in a linear dimension which is not greater than 1.0% after said article has been exposed forty times to a thermal cycling at a temperature rising from 40°
C. to 1,260°
C. in a time of 6 minutes and cooling from 1,260°
C. to 40°
C. in a time of 5 minutes; and
said article having a maximum difference value between a value on a thermal expansion curve during heating and a value on a thermal expansion curve during cooling at an identical temperature which is not greater than 0.18%.
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Abstract
A sintered aluminum titanate-mullite base ceramic having a chemical composition of not more than 0.8% of MgO, from 53 to 74% of Al2 O3, from 14 to 33% of TiO2, from 1.2 to 5% of Fe2 O3, from 6 to 20% of SiO2, and not more than 0.3% of (CaO+Na2 O+K2 O), and an amount of glass in mullite base matrices of the sintered body being not more than 5% when measured at a section of the sintered body. This aluminum titanate-mullite base ceramic is obtained by compounding from 40 to 65% of a starting material of aluminum titanate essentially consisting of from 45 to 62% of Al2 O3, from 34 to 50% of TiO2, from 3 to 7% of Fe2 O3, not more than 1% of SiO2 and not more than 0.3% of (CaO+Na2 O+K2 O) with from 35 to 60% of a starting material of mullite essentially consisting of from 18 to 32% of SiO2, from 68 to 82% of Al2 O3, and not more than 0.85% of (Fe2 O3 +TiO2 +CaO+MgO+Na2 O+K2 O), at least one of said aluminum titanate starting material and said mullite starting material being fired, and molding a resulting mixture, and firing a thus obtained molding at from 1,550° to 1,700° C. in an oxidizing atmosphere. The alumina titanate starting material may contain not more than 0.1% of MgO.
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Citations
10 Claims
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1. A sintered aluminum titanate-mullite base ceramic consisting essentially of:
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a chemical composition of not greater than 0.8% of MgO, 53 to 74% of Al2 O3, 14 to 33% of TiO2, 1.2 to 5% of Fe2 O3, 6 to 20% of SiO2, and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, and an amount of glass in mullite base matrices of the sintered ceramic being not greater than 5% when measured at a section of a body of said sintered ceramic; said sintered aluminum titanate-mullite base ceramic being formed by compounding 40 to 65% of a raw material of aluminum titanate consisting essentially of 45 to 62% of Al2 O3, 34 to 50% of TiO2, 3 to 7% of Fe2 O3, not greater than 1% of SiO2 and (CaO+Na1 O+K2 O) in an amount not greater than 0.3%, with 35 to 60% of a raw material of mullite consisting essentially of 18 to 32% of SiO2, 68 to 82% of Al2 O3, and (Fe2 O3 +TiO2 +CaO+MgO+Na2 O+K2 O) in an amount not greater than 0.8%, at least one of said aluminum titanate raw material and said mullite raw material being preliminarily fired at a temperature which is not less than 1550°
C., molding a resulting mixture of the raw materials, and subsequently firing a thus obtained molding at 1,550°
to 1,700°
C. in an oxidizing atmosphere resulting in a sintered aluminum titanate-mullite base ceramic article;said article having an average coefficient of thermal expansion at a temperature range of 40°
to 800°
C. of -2.0×
10-6 /°
C. to 2.0×
10-6 /°
C.;said article having an increment in a linear dimension which is not greater than 1.0% after said article has been exposed forty times to a thermal cycling at a temperature rising from 40°
C. to 1,260°
C. in a time of 6 minutes and cooling from 1,260°
C. to 40°
C. in a time of 5 minutes; andsaid article having a maximum difference value between a value on a thermal expansion curve during heating and a value on a thermal expansion curve during cooling at an identical temperature which is not greater than 0.18%. - View Dependent Claims (3, 4, 7)
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2. A sintered aluminum titanate-mullite base ceramic consisting essentially of:
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a chemical composition of not greater than 0.8% of MgO, 53 to 74% of Al2 O3, 14 to 33% of TiO2, 1.2 to 5% of Fe2 O3, 6 to 20% of SiO2, and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, and an amount of glass in mullite base matrices of the sintered ceramic being not greater than 5% when measured at a section of a body of said sintered ceramic; said sintered aluminum titanate-mullite base ceramic being formed by compounding 40 to 65% of a raw material of aluminum titanate consisting essentially of not greater than 1% of MgO, 45 to 62% of Al2 O3, 34 to 50% of TiO2, 3 to 7% of Fe2 O3, not greater than 1% of SiO2 and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, with 35 to 60% of a raw material of mullite consisting essentially of 18 to 32% of SiO2, 68 to 82% of Al2 O3, and (Fe2 O3 +TiO2 +CaO+MgO+Na2 O+K2 O) in an amount not greater than 0.85%, at least one of said aluminum titanate raw material and said mullite raw material being preliminarily fired at a temperature which is not less than 1550°
C., molding a resulting mixture of the raw materials, and firing a thus obtained molding at 1,550°
to 1,700°
C. in an oxidizing atmosphere resulting in a sintered aluminum titanate-mullite base ceramic article.said article having an average coefficient of thermal expansion at a temperature range of 40°
to 800°
C. of -2.0×
10-6 /°
C. to 2.0×
10-6 /°
C.;said article having an increment in a linear dimension which is not greater than 1.0% after said article has been exposed forty times to a thermal cycling at a temperature rising from 40°
C. to 1,260°
C. in a time of 6 minutes and cooling from 1,260°
C. to 40°
C. in a time of 5 minutes; andsaid article having a maximum difference value between a value on a thermal expansion curve during heating and a value on a thermal expansion curve during cooling at an identical temperature, which is not greater than 0.18%. - View Dependent Claims (5, 6, 8)
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9. A sintered aluminum titanate-mullite base ceramic consisting essentially of:
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a chemical composition of not greater than 0.8% of MgO, 53 to 74% of Al2 O3, 14 to 33% of TiO2, 1.2 to 5% of Fe2 O3, 6 to 20% of SiO2, and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, and an amount of glass in mullite base matrices of the sintered ceramic being not greater than 5% when measured at a section of a body of said sintered ceramic; said sintered aluminum titanate-mullite base ceramic being formed by compounding 40 to 65% of a raw material of aluminum titanate consisting essentially of 45 to 62% of Al2 O3, 34 to 50% of TiO2, 3 to 7% of Fe2 O3, not greater than 1% of SiO2 and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, with 35 to 60% of a raw material of mullite consisting essentially of 18 to 32% of SiO2, 68 to 82% of Al2 O3, and (Fe2 O3 +TiO2 +CaO+MgO+Na2 O+K2 O) in an amount not greater than 0.8%, at least one of said aluminum titanate raw material and said mullite raw material being preliminarily fired at a temperature which is not less than 1550°
C., molding a resulting mixture of the raw materials, and subsequently firing a thus obtained molding at 1,550°
to 1,700°
C. in an oxidizing atmosphere resulting in a sintered aluminum titanate-mullite base ceramic article.
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10. A sintered aluminum titanate-mullite base ceramic consisting essentially of:
a chemical composition of not greater than 0.8% of MgO, 53 to 74% of Al2 O3, 14 to 33% of TiO2, 1.2 to 5% of Fe2 O3, 6 to 20% of SiO2, and (CaO+Na2 O+K2 O) in an amount not greater than 0.3%, and an amount of glass in mullite base matrices of the sintered ceramic being not greater than 5% when measured at a section of a body of said sintered ceramic.
Specification
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Current AssigneeNGK Insulators Limited
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Original AssigneeNGK Insulators Limited
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InventorsHarada, Takashi, Hamanaka, Toshiyuki, Asami, Seiichi
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Primary Examiner(s)Dixon, Jr., William R.
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Assistant Examiner(s)Green, Anthony
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Application NumberUS06/886,365Time in Patent Office775 DaysField of Search501/128, 501/136, 501/153, 501/134US Class Current501/128CPC Class CodesC04B 35/18 rich in aluminium oxideC04B 35/478 based on aluminium titanates
