High integrity CoCrAl(Y) coated nickel-base superalloys

Claim 2

A high temperature oxidation and corrosion resistant coated nickel-base superalloy article having a thermal expansion coefficient value in inches per inch per ° F. measured over a temperature range of (i) 100°-1200° F. of from 8.45 to 9.05, and (ii) 100°-1740° F. of from 9.45 to 10.05; comprising: (a) a nickel-base superalloy, and (b) a first CoCrAl(Y) coating composition consisting essentially of, on a weight basis, approximately 26-32 percent chromium, 3-9 percent aluminum, and 0-1 percent yttrium, other rare earth elements, platinum or rhodium, and the balance cobalt.

Claim 3

A claim 1 article, wherein (a) said nickel-base superalloy consists essentially of, on a weight basis, ______________________________________ Ingredient IN-738 ______________________________________ C 0.17 Mn 0.20 Si 0.30 Cr 16.0 Ni Bal. Co 8.5 Mo 1.75 W 2.6 Cb 0.9 Ti 3.4 Al 3.4 B 0.01 Zr 0.10 Fe 0.50 Other 1.75 Ta ______________________________________ (b) said first coating contains 29% chromium, 6% aluminum, 1% yttrium and the balance cobalt.

Claim 4

A claim 2 article, further comprising (c) an overcoating of aluminum.

Claim 5

A claim 3 article, wherein (b) said first coating has a thickness of about 1-20 mils, (c) said second coating penetrates the first coating to a depth no nearer than 1/2 mil measured from the interface of the nickel-base superalloy and first coating.

Claim 6

A claim 4 article, wherein (b) said first coating is deposited by physical vapor deposition and the coating thickness is about 1-5 mils, (c) said second coating is deposited by chemical vapor deposition.

Claim 7

The claim 4 article, wherein

Claim 8

(b) said first coating is deposited by plasma spraying and has a coating thickness of 3-10 mils.

Claim 9

(b) said first coating is deposited by plasma spraying and has a coating thickness of 3-10 mils.