Sintered ceramic materials based on aluminium titanate, a process for their production and their use

• US 5,153,153 A
• Filed: 06/10/1991
• Issued: 10/06/1992
• Est. Priority Date: 06/22/1990
• Status: Expired due to Term

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Freudenberg, Bernhard, Gugel, Ernst, Seyer, Johannes
• Primary Examiner(s): GROUP, KARL E
• Application Number:
  US07/712,461
• Time in Patent Office: 484 Days
• Field of Search: 501/134, 501/136, 501/128, 501/131, 501/127
• US Class Current: 501/127
• CPC Class Codes: C04B 35/478 based on aluminium titanates
• CPC Class Codes: F05C 2201/021 Aluminium

Abstract

Sintered ceramic material which comprises doped aluminum titanate and mullite having the composition:

50-61.5% by weight Al₂ O₃,

36-47.5% by weight titanium oxide, expressed as TiO₂,

2.5-5% by weight SiO₂,

with the sum total of the three components adding up to 100%, and which further comprises 0.3 to 1% by weight MgO and up to 1% by weight impurities, useful as, inter alia, filters, catalyst supports and internal combustion engine parts, are prepared by mixing and shaping materials of suitable composition and then sintering the shaped composition at temperatures of 1250° to 1600° C. over a holding time of 0.5 to 100 hours.

Claims

1. Sintered ceramic body which comprise doped aluminum titanate and mullite having the composition:

50-61.5% by weight Al₂ O₃,

36-47.5% by weight titanium oxide, expressed as TiO₂,

2.5-5% by weight SiO₂,

with the sum total of the three components adding up to 100%, and which further comprise 0.3 to 1% by weight MgO, 0.015 to 0.5% by weight iron oxide, expressed as Fe₂ O₃ and up to 1% by weight impurities.

2. Sintered ceramic body as claimed in claim 1 wherein the MgO content is 0.3 to 0.6% by weight.

3. Sintered ceramic body as claimed in claim 1 wherein the iron oxide content, expressed as Fe₂ O₃, is 0.05 to 0.4% by weight.

4. Sintered ceramic body as claimed in claim 1 wherein the percentage by weight ratio of MgO to Fe₂ O₃ is between 20 and 2.

5. Sintered ceramic body as claimed in claim 2 wherein the iron oxide content, expressed as Fe₂ O₃, is 0.05 to 0.4% by weight.

6. Sintered ceramic body as claimed in claim 2 wherein the percentage by weight ratio of MgO to Fe₂ O₃ is between 20 and 2.

7. Sintered ceramic body as claimed in claim 1, wherein the sum total of the contents of unreacted Al₂ O₃ and TiO₂ after sintering is 5% or lower, by weight.

8. Sintered ceramic body as claimed in claim 1, wherein the sum total of the contents of unreacted Al₂ O₃ and TiO₂ after sintering is ≦

2.5% by weight.

9. A process for the production of sintered ceramic body which comprises the steps of mixing, shaping and sintering a composition comprising the following components:

50-61.5% by weight Al₂ O₃,

36-47.5% by weight titanium oxide, expressed as TiO₂,

2.5-5% by weight SiO₂,

with the sum total of the three components adding up to 100%, and which further comprise 0.3 to 1% by weight MgO, 0.015 to 0.5% by weight iron oxide, expressed as Fe₂ O₃ and up to 1% by weight impurities wherein the sintering of the ceramic body at temperatures of 1250°

to 1600°

C. over a holding time of 0.5 to 100 hours.

10. A process according to claim 9 wherein the sintering temperature is 1300°

to 1450°

C. over a holding time of 1 to 50 hours.

11. A process according to claim 9 wherein as a first step the components are predispersed individually or in admixture by wet grinding and the mixture of wet-ground components is subsequently processed by granulation drying.

12. A process according to claim 9 wherein the sintered ceramic body is reaction-sintered.

13. A process according to claim 9 wherein magnesium compounds are introduced into the composition as magnesium titanates, selected from the group consisting of Mg₂ TiO₄, MgTiO₃, MgTi₂ O₅, and mixtures thereof.

14. A process according to claim 9 wherein iron compounds are introduced into the composition in the form of finely dispersed α

-Fe₂ O₃ powder, in the form of iron-containing layer silicates, or in the form of iron-containing kaolin.

15. A process accordingly to claim 9 wherein iron compounds are introduced into the composition in the form of iron containing clays.