U.S. patent application number 09/972176 was filed with the patent office on 2002-12-26 for superalloy hvof powders with improved high temperature oxidation, corrosion and creep resistance.
This patent application is currently assigned to Sulzer Metco (US) Inc.. Invention is credited to Dorfman, Mitchell R., LaPierre, Kerry, Russo, Lysa.
Application Number | 20020194956 09/972176 |
Document ID | / |
Family ID | 24133164 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020194956 |
Kind Code |
A1 |
Russo, Lysa ; et
al. |
December 26, 2002 |
SUPERALLOY HVOF POWDERS WITH IMPROVED HIGH TEMPERATURE OXIDATION,
CORROSION AND CREEP RESISTANCE
Abstract
A high velocity oxygen fuel thermal spray powder comprising a
superalloy having the formula MCrAlY-X, wherein M is at least one
metal taken from the group consisting of nickel, cobalt, and iron;
X is at least one reactive element taken from the group consisting
of hafnium, rhenium, lanthanum, and tantalum; and yttrium is
present in levels greater than 1% by weight of the total
composition and up to about 6% by weight of the total composition.
In addition, the powder may be blended with an agglomeration of
M'CrAlY and a ceramic, wherein M' is at least one metal taken from
the group consisting of nickel, cobalt, and iron. The invention
offers improved high temperature oxidation, corrosion and creep
resistance.
Inventors: |
Russo, Lysa; (Hauppauge,
NY) ; Dorfman, Mitchell R.; (Smithtown, NY) ;
LaPierre, Kerry; (Troy, MI) |
Correspondence
Address: |
Ira J Schaefer Esquire
Clifford Chance Rogers & Wells LLP
200 Park Avenue
New York
NY
10166-0153
US
|
Assignee: |
Sulzer Metco (US) Inc.
|
Family ID: |
24133164 |
Appl. No.: |
09/972176 |
Filed: |
October 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09972176 |
Oct 5, 2001 |
|
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|
09535178 |
Mar 27, 2000 |
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6346134 |
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Current U.S.
Class: |
75/252 |
Current CPC
Class: |
C22C 33/0292 20130101;
C22C 1/0433 20130101; C23C 4/073 20160101; Y02T 50/60 20130101;
C22C 32/00 20130101 |
Class at
Publication: |
75/252 |
International
Class: |
C22C 001/05 |
Claims
What is claimed is:
1. A high velocity oxygen fuel thermal spray powder comprising: a
superalloy having the formulaM--Cr--Al--Y--X,wherein M is at least
one metal taken from the group consisting of nickel, cobalt, and
iron; X is at least one reactive element; and yttrium is present in
levels greater than 1% by weight of the total composition and up to
about 6% by weight of the total composition.
2. The powder in claim 1, wherein chromium is present in levels of
20-35% by weight of the total composition.
3. The powder in claim 1, wherein aluminum is present in levels of
5-15% by weight of the total composition.
4. The powder in claim 1, wherein said at least one reactive
element is taken from the group consisting of hafnium, rhenium,
lanthanum, and tantalum.
5. The powder in claim 1 or 4, wherein said at least one reactive
element is present in levels of 2-10% by weight of the total
composition.
6. The powder in claim 1, further comprising an agglomeration of a
superalloy having the formula M'-Cr-Al-Y, and a ceramic, wherein M'
is at least one metal taken from the group consisting of nickel,
cobalt, and iron.
7. The powder in claim 6, wherein said ceramic is taken from the
group consisting of alumina, yttria, and garnet.
8. The powder in claim 6, wherein said ceramic is present in a
level of 15% by weight of the agglomeration.
9. The powder in claim 6, wherein said ceramic is present in levels
of 3-15% by weight of the total composition.
10. The powder in claim 6, wherein said ceramic is present in
levels of 4.5-7.5% by weight of the total composition.
11. The powder in claim 6, wherein said agglomeration is present in
levels of 30-50% by weight of the total composition.
Description
FIELD OF THE INVENTION
[0001] This invention relates to two new families of high velocity
oxygen fuel (HVOF) thermal spray superalloy (MCrAlY-X) alloy
powders.
BACKGROUND OF THE INVENTION
[0002] Current MCrAlY compositions have been mostly designed to be
used as cast metals for high temperature (850-1100.degree. C.)
applications on components such as blades and vanes on aircraft and
land-based turbines. MCrAlY alloys are commonly used at these
elevated temperatures due to their ability to form an oxide scale,
either alumina or chromia based, which acts as a protective barrier
against high temperature oxidation and corrosion environments. The
adherence and stabilization of this scale is directly related to
the useful life of the alloy. Scales that have poor integrity and
"flake-off" cause the continual outward diffusion of key elements
in order to replace the exposed area with new oxide scale. This
process eventually depletes the alloy of its critical elements
thereby reducing its high temperature effectiveness.
[0003] Accordingly, the main object of the invention is to provide
HVOF powders that offer improved high temperature oxidation,
corrosion and/or creep resistance.
SUMMARY OF THE INVENTION
[0004] The foregoing and other objects of the present invention are
achieved, at least in part, by utilizing gas atomized MCrAlY-X
alloy compositions consisting of a metal, M, of nickel, cobalt
and/or iron, chromium with levels between 20-35 wt %, aluminum with
levels between 5-15 wt %, yttrium with levels greater than 1 wt %
and up to about 6 wt % and a reactive element, X, which can be
hafnium, rhenium, lanthanum and/or tantalum with levels between
2-10 wt %.
[0005] The compositions are unique in that they are designed to be
used as overlay coatings and deposited via the HVOF process. The
chemistries of these alloys have been especially tailored to
compensate for the relatively low temperature, oxygen-rich
environment of the HVOF combustion flame.
[0006] The addition of a reactive element to an MCrAlY composition
has been found to enhance the adhesion of the protective oxide
scale, increase the plasticity of the scale, grade the mechanical
differences between the ceramic oxide scale and the metallic base
alloy, and modify the scale growth mechanisms by controlling the
diffusion process.
[0007] The role of yttrium in the composition is to help adhere the
protective oxide scale to the coating structure below. However, it
has been found that traditional yttrium levels (1 wt % or less) are
insufficient when deposited with the HVOF process. This
insufficiency is due to the oxide formation of the yttrium forming
various phases of yttria, which are less beneficial to the oxide
adhesion process. In order to compensate for this occurrence, the
present invention includes a new family of MCrAlY compositions that
contain a higher level of yttrium (greater than 1 wt % and up to
about 6 wt %, preferably 1.5 wt % to 5.5 wt %, and most preferably
about 4 wt %) in the powder. This increased yttrium level in
conjunction with the addition of a reactive element, produce an
overlay that is better able to withstand high temperature oxidation
and corrosion environments by improving the formation and adherence
of the protective oxide scale.
[0008] For optimal performance, MCrAlY coatings must be sprayed
with a "cool" HVOF flame in order to minimize the formation of
internal oxides. This limited heat content of the flame also
minimizes the effectiveness of depositing high melting point
materials like ceramics. It has been found that by surrounding the
ceramic particles with lower melting point metallic alloys, a
higher degree of ceramic can be entrapped within the coating. These
discrete ceramic particulates within the coating help to restrict
grain growth within the alloy at high temperatures. This
restriction in turn improves the material's creep resistance.
[0009] Thus, in a first family of powders in accordance with the
present invention, a MCrAlY-X composition is specifically designed
for the HVOF deposition process. The yttrium content has been
increased to greater than 1 wt % and up to about 6 wt % to
compensate for the oxidation that occurs during deposition. The
reactive element component, X, is incorporated to improve the
formation and adhesion of the protective oxide scale. This improved
adhesion leads to increased oxidation and corrosion protection
offered by the overlay.
[0010] The present invention also includes a second family of HVOF
MCrAlY-X materials, which is a blend of (1) MCrAlY-X, and (2)
MCrAlY and ceramic, that have been designed to offer superior creep
resistance over traditional alloy compositions. This class of
alloys contains an agglomerated (spray dried) secondary component
consisting of MCrAlY+ceramic (i.e., alumina, yttria, garnet, etc.).
Thus, in addition to the advantages of the improved oxide scale
properties from the MCrAlY-X component, this class takes advantage
of the improved creep resistance provided from the addition of an
agglomerated ceramic component. The agglomerated secondary
component is present in the blend in levels of 30-50% by weight of
the total composition. The overall amount of ceramic in the bulk
powder ranges from 3-15% by weight, preferably 4.5-7.5 wt %. In a
preferred embodiment, an agglomerated powder with 15 wt %
Al.sub.2O.sub.3 and 85% CoNiCrAlY is blended with MCrAlY-X powders.
Again, this class of materials is unique in that the addition of a
secondary component, which is an agglomeration of a ceramic and a
metal, takes advantage of the HVOF flame characteristics.
[0011] Following are examples of three novel MCrAlY powders in
accordance with the present invention disclosed herein:
1 AE 7855 AE 7856 AE 7857 Chemical Analysis wt % A1 11 12 11 B 0.29
-- -- C 0.02 0.01 0.01 Co 19 36.3 22 Cr 28 21 20 Ni 29 25 37 Re 3 2
-- Si 0.03 -- -- Ta 5 -- 5 Y 4 4 4 Total All Others <0.3 <0.4
<0.2 O.sub.2 0.03 0.03 0.03 N.sub.2 0.00 0.00 0.00 Particle
Size, microns -15 .mu.m 5 2 2 Sieve Analysis +270 Mesh 0 0 0 +325
Mesh 4 5 5 -325 +15 .mu.m 91 93 94
[0012] While the invention has been described above in detail with
reference to specific embodiments, various changes and
modifications which fall within the spirit of the invention and
scope of the appended claims will become apparent to those skilled
in this art. Therefore, the invention is intended only to be
limited by the appended claims or their equivalents.
* * * * *