Ceramic fiber composite material

• US 20060280940A1
• Filed: 06/13/2006
• Published: 12/14/2006
• Est. Priority Date: 06/14/2005
• Status: Active Grant

• Current Assignee: Deutsches Zentrum Fur Luft- und Raumfahrt EV
• Original Assignee: Deutsches Zentrum Fur Luft- und Raumfahrt EV
• Inventors: Kanka, Bernhard
• Granted Patent: US 7,919,039 B2
• Time in Patent Office: Days
• US Class Current: 428/364
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/616 Liquid infiltration of green bodies or pre-forms
• CPC Class Codes: C04B 35/62236 Fibres based on aluminium oxide
• CPC Class Codes: C04B 35/6261 Milling
• CPC Class Codes: C04B 35/6263 characterised by their solids loadings, i.e. the percentage of solids
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber

Abstract

The invention relates to a particularly low-cost and flexible process for the preparation of a sintered ceramic fiber composite material consisting of oxide-ceramic continuous fibers and an oxide-ceramic matrix, and to a fiber composite material prepared by such process.

Claims

1. A process for the preparation of an oxide-ceramic fiber composite material, comprising the steps of:

a) calcinating an oxide-ceramic powder while retaining a free flowing property;

b) preparing a slip having a dynamic viscosity within a range of from 0.01 TO 0.15 Pa—

s, containing from 50 to 80% by weight of said oxide-ceramic powder, based on the total amount of the slip, from 0.1 to 25% by weight of a liquefier, based on the total amount of the slip, and water as the balance with mix-milling;

c) infiltrating oxide-ceramic continuous fibers with the slip;

d) forming a green body as a shaped article;

e) drying the green body; and

f) sintering the green body to form the oxide-ceramic fiber composite material.

2. The process according to claim 1, wherein the calcinating of said oxide-ceramic powder is effected at a temperature of at least 1250°

C.

3. The process according to claim 1, wherein a slip having a dynamic viscosity within a range of from 0.02 to 0.1 Pa·

s, is employed.

4. The process according to claim 1, wherein a slip having a solids content of at least 65% by weight, is employed.

5. The process according to claim 1, wherein a slip containing a liquefier in an amount of from 0.2 to 5% by weight, is employed.

6. The process according to claim 1, wherein a binder-free slip is employed.

7. The process according to claim 1, wherein the infiltrated continuous fibers are subjected to preliminary drying in a microwave oven before the green body is formed.

12. An oxide-ceramic fiber composite material obtainable by a process according to claim 1.

13. The oxide-ceramic fiber composite material according to claim 12, characterized by having a volume fiber content within a range of from about 8 to 50% by volume.

19. The process according to claim 1, wherein a slip having a solids content of at least 75% by weight is employed.

20. The process according to claim 1, wherein a slip containing a liquefier in an amount of from 0.2 to 0.7% by weight is employed.

8. A process for the preparation of an oxide-ceramic fiber composite material comprising the steps of:

a) infiltrating oxide-ceramic continuous fibers with a slip containing a sinter-active oxide-ceramic powder having at least two different grain size fractions with different peaks in the grain size distribution, wherein at least one of the grain size fractions has a mean grain size weighted according to volume proportions of up to 1 μ

m, and at least one other grain size fraction has a mean grain size weighted according to volume proportions of at least 2 μ

m;

b) drying the green body obtained according to step a); and

c) sintering the green body to form the oxide-ceramic fiber composite material.

9. The process according to claim 8, wherein an oxide-ceramic powder containing at least one grain size fraction having a mean grain size of up to 0.5 μ

m is employed.

10. The process according to claim 8, wherein an oxide-ceramic powder containing at least one further grain size fraction having a mean grain size weighted according to volume proportions of at least 10 μ

m is employed.

11. The process according to claim 8, wherein grain size fractions in the fiber composite material are independently employed in proportions of at least 10% by volume

14. An oxide-ceramic fiber composite material obtainable by a process according to claim 8.

15. The oxide-ceramic fiber composite material according to claim 14, wherein the fiber content is within a range of from 5 to 50% by volume.

16. The oxide-ceramic fiber composite material according to claim 14 having a volume fiber content within a range of from about 20 to 45% by volume.

17. The oxide-ceramic fiber composite material according to claim 14 wherein its fiber content is within a range of from about 5 to 20% by volume.

18. The process according to claim 11 wherein said fiber composite material has grain size fractions with at least one grain size fraction having a larger mean grain size weighted according to volume proportions and a lower volume proportion than a grain size fraction having a smaller volume-average grain size.