Low thermal expansion ceramic bodies containing a benitoite-type phase

Patent metadata

Field	Value
Publication number	US-9682890-B2
Application number	US-201414915961-A
Country	US
Kind code	B2
Filing date	Sep 3, 2014
Priority date	Sep 6, 2013
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

Ceramic materials and ceramic bodies are disclosed herein, such as low thermal expansion ceramic materials or ceramic bodies, such as ceramic bodies comprising a benitoite-type phase.

First claim

What is claimed is:

1. A microcracked ceramic body comprising one or more phases, wherein at least one phase is a cyclosilicate or cyclogermanate compound whose crystal structure is isostructural with that of mineral benitoite and belongs to space group P 6 m2.

2. The microcracked ceramic body of claim 1 wherein the at least one phase that is a cyclosilicate or cyclogermanate compound comprises the composition BaZr x Ti y Sn z Si 3 O 9 , wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1.

3. The microcracked ceramic body of claim 1 , wherein micro-cracks in the ceramic body contribute to low coefficient of thermal expansion such that the ceramic body exhibits a mean coefficient of thermal expansion from 25 to 1000° C. of not more than 40×10 −7 ° C. −1 .

4. The microcracked ceramic body of claim 3 , wherein the mean coefficient of thermal expansion from 25 to 1000° C. is no more than 15×10 −7 ° C. −1 .

5. A microcracked ceramic body, comprising:
a compound having a crystal structure isostructural with that of mineral benitoite and of a formula MM′M″ 3 O 9 , wherein M comprises one or more elements selected from the group consisting of strontium, lead, calcium, and barium; wherein M′ comprises one or more elements selected from the group consisting of zirconium, titanium, tin, hafnium, silicon, and cerium; and wherein M″ comprises one or more elements selected from the group consisting of silicon and germanium; and
micro-cracks in the ceramic body contributing to low coefficient of thermal expansion such that the ceramic body exhibits a mean coefficient of thermal expansion over temperatures ranging from 25 to 1000° C. of not more than 40×10 −7 ° C. −1 .

6. The microcracked ceramic body of claim 5 , wherein M comprises barium.

7. The microcracked ceramic body of claim 5 , wherein M″ comprises silicon.

8. The microcracked ceramic body of claim 5 , wherein silicon and/or germanium atoms of M″ are bonded to four oxygen atoms located at corners of a tetrahedron.

9. The microcracked ceramic body of claim 8 , wherein (Si,Ge)O 4 tetrahedra are linked to one another at the corners to form isolated three-member rings in crystal structure of the microcracked ceramic body.

10. A microcracked ceramic body, comprising:
one or more phases having a crystal structure isostructural with that of mineral benitoite and having a composition within a BaZrSi 3 O 9 —BaTiSi 3 O 9 —BaSnSi 3 O 9 system, where BaZrSi 3 O 9 , BaTiSi 3 O 9 , and BaSnSi 3 O 9 are boundary points that define a compositional space for the system covering BaZrSi 3 O 9 , BaTiSi 3 O 9 , BaSnSi 3 O 9 , and combinations thereof; and
micro-cracks in the ceramic body contributing to low coefficient of thermal expansion such that the ceramic body exhibits a mean coefficient of thermal expansion over temperatures ranging from 25 to 1000° C. of not more than 40×10 −7 ° C. −1 .

11. The microcracked ceramic body of claim 10 , wherein the one or more phases more specifically comprise at least two phases having crystal structure isostructural with that of mineral benitoite.

12. The microcracked ceramic body of claim 11 , wherein one of the phases having crystal structure isostructural with that of mineral benitoite is Ba(Zr a Ti b Sn c )Si 3 O 9 , where 0≦a≦1, 0≦b≦0.5, 0≦c≦1, and a+b+c=1.

13. The microcracked ceramic body of claim 12 , wherein at least another of the phases having crystal structure isostructural with that of mineral benitoite is Ba(Zr d Ti e Sn f )Si 3 O 9 , where 0≦d≦0.4, 0.6≦e≦1, 0≦f≦0.4, and d+e+f=1.

14. The microcracked ceramic body of claim 10 , wherein the one or more phases having a crystal structure isostructural with that of mineral benitoite that include at least one of:
a structure of Ba(Zr a Ti b Sn c )Si 3 O 9 , where 0≦a≦1, 0≦b≦0.5, 0≦c≦1, and a+b+c=1; and
a structure of Ba(Zr d Ti e Sn f )Si 3 O 9 , where 0≦d≦0.4, 0.6≦e≦1, 0≦f≦0.4, and d+e+f=1.

15. The microcracked ceramic body of claim 14 , wherein, in the BaZrSi 3 O 9 —BaTiSi 3 O 9 —BaSnSi 3 O 9 system, the boundary point BaZrSi 3 O 9 is defined as point A, the boundary point BaTiSi 3 O 9 is defined as point B, a combination of 40% BaTiSi 3 O 9 and 60% BaSnSi 3 O 9 in molar weight is defined as point C, and a combination of 75% BaZrSi 3 O 9 and 25% BaSnSi 3 O 9 in molar weight is defined as point D,
wherein a molar weighted average composition of all phases having a crystal structure isostructural with that of mineral benitoite in the compositional space of the system of the microcracked ceramic body lies within a region of the system defined by points A, B, C, and D, where weighted molar average composition of the phases having a crystal structure isostructural with that of mineral benitoite is calculated given by Ba(Zr g Ti h Sn i )Si 3 O 9 where g=[(X 1 )(a)+(X 2 )(d)]/(X 1 +X 2 ), h=[(X 1 )(b)+(X 2 )(e)]/(X 1 +X 2 ), and i=[(X 1 )(c)+(X 2 )(f)]/(X 1 +X 2 ) and where X 1 is the mole fraction of the phase of Ba(Zr a Ti b Sn c )Si 3 O 9 in the ceramic and X 2 is the mole fraction of phase of Ba(Zr d Ti e Sn f )Si 3 O 9 in the ceramic.

16. The microcracked ceramic body of claim 15 , wherein in the BaZrSi 3 O 9 —BaTiSi 3 O 9 —BaSnSi 3 O 9 system a combination of 75% BaTiSi 3 O 9 and 25% BaSnSi 3 O 9 in molar weight is defined as point E, and a combination of 90% BaZrSi 3 O 9 and 10% BaSnSi 3 O 9 in molar weight is defined as point F,
wherein the molar weighted average composition of all phases having a crystal structure isostructural with that of mineral benitoite in the compositional space of the system of the microcracked ceramic body lies within a region of the system defined by points A, B, E, and F.

17. The microcracked ceramic body of claim 10 , having a high melting point, that being greater than 1450° C.

18. A microcracked ceramic body, comprising:
a compound of a formula MM′M″ 3 O 9 , wherein M comprises one or more elements selected from the group consisting of strontium, lead, calcium, and barium; wherein M′ comprises one or more elements selected from the group consisting of zirconium, titanium, tin, hafnium, silicon, and cerium; and wherein M″ comprises one or more elements selected from the group consisting of silicon and germanium; and
micro-cracks in the ceramic body contributing to low coefficient of thermal expansion such that the ceramic body exhibits a mean coefficient of thermal expansion over temperatures ranging from 25 to 1000° C. of not more than 40×10 −7 ° C. −1 .

19. The microcracked ceramic body of claim 18 , wherein M comprises barium.

20. The microcracked ceramic body of claim 18 , wherein M″ comprises silicon.

21. The microcracked ceramic body of claim 18 , wherein silicon and/or germanium atoms of M″ are bonded to four oxygen atoms located at corners of a tetrahedron.

22. The microcracked ceramic body of claim 21 , wherein (Si,Ge)O 4 tetrahedra are linked to one another at the corners to form isolated three-member rings in crystal structure of the microcracked ceramic body.

23. A microcracked ceramic body, comprising:
one or more phases having a composition within a BaZrSi 3 O 9 —BaTiSi 3 O 9 —BaSnSi 3 O 9 system, where BaZrSi 3 O 9 , BaTiSi 3 O 9 , and BaSnSi 3 O 9 are boundary points that define a compositional space for the system covering BaZrSi 3 O 9 , BaTiSi 3 O 9 , BaSnSi 3 O 9 , and combinations thereof; and
micro-cracks in the ceramic body contributing to low coefficient of thermal expansion such that the ceramic body exhibits a mean coefficient of thermal expansion over temperatures r

Assignees

• Corning Inc

Inventors

• Knapp Karen Jo
• Merkel Gregory Albert

Classifications

• C04B2235/80

  Phases present in the sintered or melt-cast ceramic products other than the main phase · CPC title

• C04B35/16 Primary

  based on silicates other than clay {(zircon C04B35/48)} · CPC title

• C04B2235/761

  Unit-cell parameters, e.g. lattice constants · CPC title

• C04B2235/76

  Crystal structural characteristics, e.g. symmetry · CPC title

• C04B2235/349

  Clays, e.g. bentonites, smectites such as montmorillonite, vermiculites or kaolines, e.g. illite, talc or sepiolite · CPC title