Claims
- 1. A method of forming a corrosion resistant coating on an article composed of a nickel-base alloy, the method comprising the steps of:
- (a) coating the article with an overlay comprising M Cr Al Y where M includes Co, Fe, Ni or NiCo by a physical vapor deposition method;
- (b) enclosing the article coated according to step (a) in a chamber together with a particulate pack including coating material and a halide activator; and
- (c) cyclically varying the pressure of an inert gas, a reducing gas, or a mixture of said gases within the chamber while maintaining the contents of the chamber at a temperature sufficient to transfer coating material on to the surface of the overlay to form a diffusion coating therewith.
- 2. A method according to claim 1 in which the overlay coating in weight percent comprises Co-25Cr-12.5Al-0.35 Y.
- 3. A method according to claim 1 in which the overlay coating comprises Ni-37Cr-3Ti-2Al.
- 4. A method of claim 1, claim 2 or claim 3 in which the coating material is chromium, boron or silicon.
- 5. A method according to claim 1 in which the overlay is deposited by plasma-arc or flame spraying.
- 6. A method according to claim 1, claim 2 or claim 3 in which the pack comprises a powder mixture of aluminum, AlF.sub.3 and Al.sub.2 O.sub.3.
Priority Claims (1)
Number |
Date |
Country |
Kind |
7926456 |
Jul 1979 |
GBX |
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Parent Case Info
This is a continuation of application Ser. No. 172,972 filed July 28, 1980, now abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (5)
Number |
Date |
Country |
2829369 |
Jan 1979 |
DEX |
2399487 |
Mar 1979 |
FRX |
2407272 |
May 1979 |
FRX |
2003935 |
Mar 1979 |
GBX |
1549845 |
Aug 1979 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
172972 |
Jul 1980 |
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