High temperature insulation for ceramic matrix composites

• US 6,676,783 B1
• Filed: 02/22/2000
• Issued: 01/13/2004
• Est. Priority Date: 03/27/1998
• Status: Expired due to Term

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Westinghouse Power Corporation
• Inventors: Merrill, Gary B., Morrison, Jay Alan
• Primary Examiner(s): Mayes, Curtis
• Application Number:
  US09/507,794
• Time in Patent Office: 1,421 Days
• Field of Search: 156/89.11, 156/89.23, 156/325, 264/681, 427/180, 106/605
• US Class Current: 156/89.11
• CPC Class Codes: C04B 14/30 Oxides other than silica ferrites C04B14/363
• CPC Class Codes: C04B 20/004 inorganic
• CPC Class Codes: C04B 2111/28 Fire resistance, i.e. materials resistant to accidental fires or high temperatures
• CPC Class Codes: C04B 28/34 containing cold phosphate binders

Abstract

A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

Claims

1. A method of insulating a ceramic substrate when exposed to temperatures in excess of 1300°

C. by positioning a ceramic-based material composition having a high temperature resistance and containing contacting hollow oxide-based spheres manufactured at high enough temperatures to make them stable at 1600°

C. over the ceramic substrate, which has a higher strength but lower temperature resistance than the ceramic-based material composition where the high temperature resistant ceramic-based material composition has an erosion resistance of approximately 4.5 g/kg to approximately 7.5 g/kg, when measured at 1100°

C., a 15°

impingement angle, and an erodent speed of 900 ft/s.

2. A method of insulating a ceramic substrate for use in a high temperature environment in excess of approximately 1300°

C., comprising;

positioning over the ceramic substrate, a ceramic-based material composition having a temperature resistance in excess of approximately 1300°

C. and containing;

a plurality of hollow oxide-based spheres,

a phosphate binder, and

at least one oxide filler material, the binder at least partially filling at least some gaps between the spheres and the filler material

wherein the ceramic-based material composition has a lower strength but higher temperature resistance than the ceramic substrate.

3. The method of claim 2, where the high temperature resistant ceramic-based material composition is stable at temperatures up to approximately 1600°

C.

4. The method of claim 2, where the high temperature resistant ceramic-based material composition has a coefficient of thermal expansion in the range of approximately 5.7×

10<sup>−

6</sup> mm/mm °

C. to approximately 10×

10<sup>−

6</sup> mm/mm °

C.

5. The method of claim 2, where at least some of the spheres are selected from one or more of the following:

Mullite spheres, Alumina spheres, and stabilized Zirconia spheres.

6. The method of claim 5, where at least some of the Mullite spheres have a diameter in the range of approximately 0.4 to approximately 1.8 mm;

at least some of the Alumina spheres have a diameter in the range of approximately 0.3 to approximately 1 mm; and

at least some of the stabilized Zirconia spheres have a diameter in the range of approximately 0.6 to approximately 1.2 mm.

7. The method of claim 2, where the high temperature resistant ceramic-based material composition has an erosion resistance of approximately 4.5 g/kg to approximately 7.5 g/kg, when measured at 1100°

C., and 15°

impingement angle, and an erodent speed of 900 ft/s.