Oxidation resistant and low coefficient of thermal expansion NiAl-CoCrAlY alloy

• US 6,793,706 B1
• Filed: 09/10/2002
• Issued: 09/21/2004
• Est. Priority Date: 09/29/2000
• Status: Expired due to Fees

• Current Assignee: The Ohio Aerospace Institute
• Original Assignee: The Ohio Aerospace Institute
• Inventors: Hebsur, Mohan G.
• Primary Examiner(s): JENKINS, DANIEL J
• Application Number:
  US10/238,231
• Time in Patent Office: 742 Days
• Field of Search: 752/44
• US Class Current: 75/244
• CPC Class Codes: B22F 2201/02 Nitrogen
• CPC Class Codes: B22F 2202/03 Treatment under cryogenic or supercritical conditions
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 9/04 starting from solid material, e.g. by crushing, grinding or milling C22C1/1084 takes precedence; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C
• CPC Class Codes: C22C 1/1084 by mechanical alloying (blending, milling)
• CPC Class Codes: C22C 32/0068 only nitrides
• CPC Class Codes: C23C 28/00 Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D

Abstract

A bond coat composition for use in thermal barrier coatings comprises a NiAl—CoCrAlY matrix containing particles of AlN dispersed therein. The bond coat composition is prepared by croymilling NiAl and CoCrAlY in liquid nitrogen.

Claims

1. A particulate reinforced NiAl—

CoCrAlY—

AlN composite comprising;

a NiAl—

CoCrAlY matrix having particles of AlN dispersed therein, said composite containing from about 10 to about 15 volume percent of said AlN particles.

2. A composite as in claim 1, wherein said composite further comprises from about 15 to about 30 volume percent CoCrAlY and the remainder is NiAl.

3. A composite as in claim 2, having an average coefficient of thermal expansion of less than about 16 ppm/°

C. at temperatures less than 1150°

C.

4. A composite as in claim 2, having a cyclic oxidation resistance at 200 cycles and 1165°

C. of about −

3 mg/cm2.

5. A composite as in claim 2, having a cyclic oxidation resistance at 200 cycles and 1200°

C. of about −

13 mg/cm2.

6. A composite as in claim 2, wherein said AlN particles have a size in the range of from about 10 to about 50 nanometers.

7. A composite as in claim 1, wherein said composite consists essentially of NiAl, CoCrAlY and AlN.

8. A bond coat having a reduced coefficient of thermal expansion for use in a thermal barrier coating for Ni-based superalloys comprising a particulate reinforced NiAl—

CoCrAlY—

AlN composite including;

a NiAl—

CoCrAlY matrix having particles of AlN dispersed therein, said composite further comprising from about 15 to about 30 volume percent CoCrAlY, the remainder being NiAl.

9. A bond coat as in claim 8, wherein said matrix and particulate are formed by cryomilling NiAl and CoCrAlY in liquid nitrogen.

10. A bond coat as in claim 9, securing a Ni-based superalloy to a zirconia thermal barrier.