U.S. patent application number 11/788299 was filed with the patent office on 2007-08-30 for corrosion resistant superalloy with improved oxidation resistance.
This patent application is currently assigned to Siemens Power Generation, Inc.. Invention is credited to Douglas J. Arrell, Allister W. James.
Application Number | 20070199629 11/788299 |
Document ID | / |
Family ID | 34102111 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070199629 |
Kind Code |
A1 |
James; Allister W. ; et
al. |
August 30, 2007 |
Corrosion resistant superalloy with improved oxidation
resistance
Abstract
An improved nickel-based superalloy having high corrosion and
oxidation resistance and good compatibility with a thermal barrier
coating. The enhanced oxidation resistance and compatibility with
the thermal barrier coating results from the inclusion of two or
more rare earth elements. The superalloy is useful for the
fabrication of components for a gas turbine.
Inventors: |
James; Allister W.;
(Orlando, FL) ; Arrell; Douglas J.; (Oviedo,
FL) |
Correspondence
Address: |
Siemens Corporation;Intellectual Property Department
170 Wood Avenue South
Iselin
NJ
08830
US
|
Assignee: |
Siemens Power Generation,
Inc.
|
Family ID: |
34102111 |
Appl. No.: |
11/788299 |
Filed: |
April 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP05/57043 |
Dec 21, 2005 |
|
|
|
11788299 |
Apr 19, 2007 |
|
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Current U.S.
Class: |
148/428 ;
420/443 |
Current CPC
Class: |
C22C 19/057 20130101;
C22C 19/056 20130101; C22C 19/055 20130101 |
Class at
Publication: |
148/428 ;
420/443 |
International
Class: |
C22C 19/05 20060101
C22C019/05 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0001] The U.S. Government has a paid-up license in the invention
and the right in limited circumstances to require that patent owner
to license others on reasonable terms as provided for by the terms
of DE-FC26-05NT42644 awarded by the Department of Energy.
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2004 |
SE |
0403162-1 |
Claims
1. A nickel-based superalloy consisting essentially of materials as
expressed in weight percentages: 21.0 to 24.0 Cr; 18.0 to 20.0 Co;
0 to 0.5 Mo; 1.5 to 2.5 W; 1.0 to 2.0 Ta; 1.5 to 2.3 Al; 3.4 to 4.0
Ti; 0.7 to 1.2 Nb; 0.05 to 0.3 Hf; 0.05 to 0.3 Si; 0.002 to 0.008
B; 0.010 to 0.040 Zr; 0.10 to 0.20 C; 0.001 to 0.1 of a mixture of
two or more rare earth elements selected from the group of La, Ce,
Nb, Dy, Pr, Sm and Gd; and and the balance formed from Ni.
2. The superalloy of claim 1, wherein the alloy consisting
essentially of materials as expressed in weight percentages: 22.0
to 22.8 Cr; 18.5 to 19.5 Co; 0 to 0.2 Mo; 1.8 to 2.2 W; 1.3 to 1.5
Ta; 1.8 to 2.0 Al; 3.6 to 3.8 Ti; 0.9 to 1.1 Nb; 0.1 to 0.25 Hf;
0.15 to 0.25 Si; 0.004 to 0.006 B; 0.020 to 0.030 Zr; 0.13 to 0.17
C; 0.01 to 0.05 of a mixture of two or more rare earth elements
selected from the group of La, Ce, Nb, Dy, Pr, Sm, and Gd; and and
the balance formed from Ni.
3. The superalloy of claim 1, wherein the alloy wherein the alloy
consisting essentially of materials as expressed in weight
percentages: 22.4. Cr; 19.0 Co; 2.0 W; 1.4 Ta; 1.9 Al; 3.7 Ti; 1.0
Nb; 0.2 Hf; 0.2 Si; 0.005 B; 0.025 Zr; 0.15 C; 0.02 of a mixture of
two or more rare earth elements selected from the group of La, Ce,
Nb, Dy, Pr, Sm, and Gd; and and the balance formed from Ni.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This application is a continuation-in-part of international
patent application PCT/EP2005/057043 filed on Dec. 21, 2005, and
claiming priority of Sweden application 0403162-1 filed on Dec. 23,
2004, which international application was published in English as
WO 2006/067189 on Jun. 29, 2006.
FIELD OF THE INVENTION
[0003] The invention relates to a nickel-based superalloy with very
high corrosion resistance and enhanced oxidation resistance and
more particularly, to a nickel-based superalloy for directionally
solidified and conventionally cast components suited for use in gas
turbine engines.
BACKGROUND OF THE INVENTION
[0004] Nickel-base superalloys have a very good material strength
at high temperatures. These properties permit their use in
components for gas turbine engines where the retention of excellent
mechanical properties at high temperatures is required. The use of
these alloys at increasingly higher temperatures requires that a
coating be applied to the superalloy component for thermal
protection. The coating typically consists of applying a bondcoat
to the superalloy and then a thermal barrier coating (TBC) to the
bondcoat. Typical bond coats are alloys of the type MCrAlX where M
is Ni, Co, or Fe and X is commonly Y, Zr, or Hf. The bondcoat tends
to degrade during prolonged high temperature exposure. The degraded
bondcoat does not adequately adhere the thermal barrier coating to
the superalloy component. As a result, spallation of the TBC occurs
with complete loss of thermal protection to the component. The rate
at which the bondcoat degrades depends upon the composition of the
superalloy to which it is applied. Generally alumina forming
superalloys exhibit longer bondcoat lifetimes than chromia forming
superalloys. However, it is often preferable to use high chromium
containing superalloys for very high corrosion resistance. A need
exists for a superalloy with a lower propensity to promote bondcoat
degradation and significantly enhance the resistance of the TBC to
spallation.
SUMMARY OF THE INVENTION
[0005] This application is directed to a nickel-based superalloy
that has high corrosion and oxidation resistance and good
compatibility with a thermal barrier coating deposited thereon. The
nickel-based superalloy may be formed from materials in the
following weight percentages: 21.0 to 24.0 Cr; 18.0 to 20.0 Co; 0
to 0.5 Mo; 1.5 to 2.5 W; 1.0 to 2.0 Ta; 1.5 to 2.3 Al; 3.4 to 4.0
Ti; 0.7 to 1.2 Nb; 0.05 to 0.3 Hf; 0.05 to 0.3 Si; 0.002 to 0.008
B; 0.010 to 0.040 Zr; 0.10 to 0.20 C; 0.001 to 0.1 of a mixture of
two or more rare earth elements selected from the group of La, Ce,
Nb, Dy, Pr, Sm, and Gd; and the balance formed from Ni. Preferably,
the superalloy may include the following materials in the following
weight percentages: 22.0 to 22.8 Cr; 18.5 to 19.5 Co; 0 to 0.2 Mo;
1.8 to 2.2 W; 1.3 to 1.5 Ta; 1.8 to 2.0 Al; 3.6 to 3.8 Ti; 0.9 to
1.1 Nb; 0.1 to 0.25 Hf; 0.15 to 0.25 Si; 0.004 to 0.006 B; 0.020 to
0.030 Zr; 0.13 to 0.17 C; 0.01 to 0.05 of a mixture of two or more
rare earth elements selected from the group of La, Ce, Nb, Dy, Pr,
Sm, and Gd; and the balance formed from Ni. The superalloy may also
be formed from the following materials in weight percentages
including: 22.4 Cr; 19.0 Co; 2.0 W; 1.4 Ta; 1.9 Al; 3.7 Ti; 1.0 Nb;
0.2 Hf; 0.2 Si; 0.005 B; 0.025 Zr; 0.15 C; 0.02 of a mixture of two
or more rare earth elements selected from the group of La, Ce, Nb,
Dy, Pr, Sm, and Gd; and the balance formed from Ni.
DETAILED DESCRIPTION OF THE INVENTION
[0006] This invention is directed to a high chromium superalloy
that promotes superior corrosion and oxidation resistance and an
improved compatibility with a TBC applied to the superalloy via a
bondcoat. In one embodiment, the superalloy may be formed from
materials in the following weight percentages: 21.0 to 24.0 Cr;
18.0 to 20.0 Co; 0 to 0.5 Mo; 1.5 to 2.5 W; 1.0 to 2.0 Ta; 1.5 to
2.3 Al; 3.4 to 4.0 Ti; 0.7 to 1.2 Nb; 0.05 to 0.3 Hf; 0.05 to 0.3
Si; 0.002 to 0.008 B; 0.010 to 0.040 Zr; 0.10 to 0.20 C; 0.001 to
0.1 of a mixture of two or more rare earth elements selected from
the group of La, Ce, Nb, Dy, Pr, Sm, and Gd; and the balance formed
from Ni. The inclusion of rare earth elements selected from the
group of La, Ce, Nb, and Dy provides enhanced coating performance.
Furthermore, the desired coating performance is a result of the use
of two or more rare earth elements rather than a single
element.
[0007] A chromium content of at least 21 weight percent results in
excellent levels of high temperature corrosion resistance. Although
the aluminum content is relatively low compared to levels that are
generally present in superalloys with high oxidation resistance,
oxidation resistance is enhanced by the presence of the rare earth
elements, the silicon, and the hafnium present in the
superalloy.
[0008] The silicon in the alloy permits the formation of SiO.sub.2
at the surface oxide layer to provide oxidation resistance.
However, the level of silicon must be kept at levels below 0.2
weight percent, a level where the silicon content is detrimental to
the performance of the alloy. The addition of the hafnium at levels
similar to that of the silicon compensates for the limitation in
silicon level without the detrimental performance resulting from
excessive silicon levels.
[0009] Particularly the addition of the rare earth elements
dramatically improves the oxidation resistance. The presence of
rare earth elements is believed to promote the diffusion of
aluminum to the surface increasing the proportion of alumina in the
scale relative to alloys where no rare earth elements are
present.
[0010] The presence of the rare earth elements enhances the coating
life. This enhancement is attributed to the ability of the rare
earth elements to form sulfides and oxysulfides fixing sulfur
impurities which prevents their diffusion to the surface permitting
the degradation of the alumina scale on the superalloy adjacent to
the bondcoat.
[0011] A preferred superalloy for high corrosion resistance and an
improved oxidation resistance may be formed from materials in the
following weight percentages: 22.0 to 22.8 Cr; 18.5 to 19.5 Co; 0
to 0.2 Mo; 1.8 to 2.2 W; 1.3 to 1.5 Ta; 1.8 to 2.0 Al; 3.6 to 3.8
Ti; 0.9 to 1.1 Nb; 0.1 to 0.25 Hf; 0.15 to 0.25 Si; 0.004 to 0.006
B; 0.020 to 0.030 Zr; 0.13 to 0.17 C; 0.01 to 0.05 of a mixture of
two or more rare earth elements selected from the group of La, Ce,
Nb, Dy, Pr, Sm, and Gd; and the balance formed from Ni. A most
preferred superalloy composition may be formed from materials in
the following weight percentages: 22.4 Cr; 19.0 Co; 2.0 W; 1.4 Ta;
1.9 Al; 3.7 Ti; 1.0 Nb; 0.2 Hf; 0.2 Si; 0.005 B; 0.025 Zr; 0.15 C;
0.02 of a mixture of two or more rare earth elements selected from
the group of La, Ce, Nb, Dy, Pr, Sm, and Gd; and the balance formed
from Ni.
[0012] Alternatives for the alloy composition and other variations
within the range provided will be apparent to those skilled in the
art. Variations and modifications can be made without departing
from the scope and spirit of the invention as defined by the
following claims.
* * * * *