An oxidation resistant coating for titanium alloys and titanium alloy matrix composites comprises an MCrAlX material. M is a metal selected from nickel, cobalt, and iron. X is an active element selected from Y, Yb, Zr, and Hf

Brindley, William J.

Rouge, Carl J.

Smialek, James L.

English

NASA Technical Reports Server

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US005116690A 
United States Patent [I91 pi] Patent Number: 5,116,690 
Brindley et al. 1451 Date of Patent: May 26, 1992 
OXIDATION RESISTANT COATING FOR 
TITANIUM ALLOYS AND TITANIUM 
ALLOY MATRIX COMPOSITES 
Inventors: William J. Brindley; James L. 
Smialek, both of Strongsville; Carl J. 
Rouge, Cleveland, all of Ohio 
Assignee: The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
Appl. No.: 682,160 
Filed: Apr. 1, 1991 
Int. ( 3 . 5  ........................ B32B 5/02; B32B 15/01; 
B32B 15/20 
U.S. Cl. .................................... 428/614; 428/660, 
428/661 
Field of Search ............... 428/614, 615, 660, 661, 
428/651, 656 
~561 References Cited 
U.S. PATENT DOCUMENTS 
Re. 32,121 4/1986 Gupta et al. ........................ 428/656 
4,419,416 12/1983 Gupta et al. ........................ 428/656 
4,758,480 7/1988 Hecht et al. ........................ 428/682 
4,786,566 11/1988 Siemers ............................... 428/568 
4,801,513 7/1989 Duhl et al. .......................... 428/628 
4,904,546 2/1990 Jackson ............................... 428/661 
4,933,239 6/19W Olson et al. ......................... 428/557 
OTHER PUBLICATIONS 
INCO, “High Temperature High Strength Nickel Base 
Alloys”, 1984, pp. 4 and 16. 
Primary Examiner-Michael Lewis 
Assistant Examiner-Valerie Lund 
Attorney, Agent, or Firm-Gene E. Shook; James A. 
Mackin; Guy M. Miller 
P71 ABSTRACT 
An oxidation resistant coating for titanium alloys and 
titanium alloy matrix composites comprises an MCrAlX 
material. M is a metal selected from nickel, cobalt, and 
iron. X is an active element selected from Y, Yb, Zr and 
Hf. 
6 Claims, 2 Drawing Sheets 
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https://ntrs.nasa.gov/search.jsp?R=19920019847 2020-03-24T07:14:59+00:00Z
US. Patent May 26,1992 Sheet 1 of 2 5,116,690 
U.S. Patent May 26, 1992 Sheet 2 of 2 5,116,690 
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FIG. 2 
FIG. 3 
5,116,690 
1 
and an outer zone which contains the protective coat- 
DISCLOSURE OF THE INVENTION 
A practical and effective oxidation resistant coating 
constructed in accordance with the present invention 
comprises MCrAlX where M is nickel, cobalt, iron or 
combinations thereof and X is an active element, such as 
Y,Yb,Zr, or Hf. This oxidation resistant coating is ap- 
10 plied to titanium alloys and titanium-alloy-matrix com- 
posites. 
The advantage of this invention is good adhesion of 
the coatings without cracking, as compared to pack 
cementation or ceramic coatings that have been re- This invention is concerned with coatings for tita- 15 ported for these materials. One novel feature of this 
invention is particularly directed to a practical and titanium-alloy-matrix composites. While MCrAIX coat- effective oxidation resistant coating for these materials. ings are in the prior art they have not been ap- 
components, but these coatings have not been applied to 2o positas 
titanium alloys or titanium alloy matrix composites. 
While some titanium alloys have acceptable oxidation 
resistance, this oxidation resistance usually comes at the 
cost of desirable mechanical properties. 
um-based alloys is a very recent field of endeavor. Inter- 
metallic alloys of titanium typically have higher specific 
attractive candidates for structural materials in aero- 
dize rapidly at the desired use temperatures, with a 
consequent deterioration of material properties. There- 
fore, there is an intense need for coatings that can inhibit 
deleterious oxidation without compromising the base 
material properties. 
oxidation protection of superalloy components in air- 
craft gas turbines but have not been investigated for use 
on titanium alloys or titanium-alloy-matrix composites. 
provide oxidation protection for titanium alloys and 
titanium-alloy-matrix Composites without Sacrificing 
desirable mechanical properties. 
A further object of the invention is to provide a prac- 
tical and effective oxidation resistant coating for tita- 45 
OXIDATION RESISTANT COATING FOR ing. 
TITANIUM ALLOYS AND TITAhTUM ALLOY 
MATRIX COMPOSITES 
ORIGIN OF THE INVENTION 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured and used by or for the Government for govern- 
mental purposes without the payment of any royalties 
thereon or therefor. 
TECHNICAL FIELD 
5 
nium and titanium matrix composites. The coated structure is the use of MCrAlX materials on 
Overlay have been for supralloy plied to titanium alloys and titanium-a]loy-matrix corn- 
BRIEF DESCRIPTION OF THE DRAWINGS 
The objects, advantages and novel features of the 
invention will be more fully apparent from the follow- 
Research into oxidation resistant coatings for titani- 25 ing detailed description when read in connection with 
the accompanying drawings wherein 
is an enlarged vertical section view of a sub- 
is an enlarged photomicrograph of a titanium 
FIG. 
FIG. 
strengths than current superalloys and are therefore strate coated in accordance with the present invention; 
space applications. However, many titanium alloys oxi- 30 alloy coated in accordance with the present invention, 
and 
FIG. 3 is an photomicrograph of a titanium- 
al~oy-mat~x composite coated in accordance with the 
present invention. 
BEST MODE FOR CARRYING OUT THE 
INVENTION 
Referring now to the drawings there is shown in 
FIG. 1 an oxidation resistant coating 10 of the present 
It is, therefore, an object Of the present invention to 40 invention. The coating is thema] sprayed and corn- 
a proven oxidation resistant metal, s,,& as 
MCrAlX, where the "M' stands for Ni, Co, Fe or corn- 
binations thereof and X is an active element such as Y, 
yb, Zr or Hf. 
The coating 10 is applied to a substrate 12 as shown in 
FIG. 1. Ti3Al+Nb and SiC/Ti3Al+Nb composite 
materials were used for the substrate 12 where S ic  is 
the fiber used in the composite and Ti,AI+Nb is the 
matrix. 
NiCrAlY coatings 0.002 in. to 0.010 in. thick, with 
compositions of Ni-(12-38)W %Cr- (&12)~  %A]- 
(0.3-0.95)~ %Y, were applied on the major surfaces of 
coupons of Ti3AI+Nb and SiC/Ti3Al+Nb composite 
materials as shown in FIGS. 2 and 3. More particularly, 
U.S. Pat. NO. 4,758,480 to'Hecht et al is directed to 55 FIG. 2 is an optical micrograph of a cross section of an 
as-plasma sprayed Ni-35 Cr-6A1-0.95Y coating on a 
Ti3AI+Nb substrate. FIG. 3 is an optical micrograph of 
an as-plasma sprayed Ni-35Cr-6A1-0.95Y coating on a 
SiC/Ti3Al+Nb composite substrate. 
-325 mesh +5  pm NiCrAlY powders were low 
pressure plasma sprayed at a chamber pressure of 30-40 
torr directly onto the surface of the substrate 12. Trial 
coatings where thermal cycle tested in cycles of 1 hour 
at 982" C. and cooling to 150' C. The coatings remained 
U.S. Pat. No. 4,933,239 to Olson et al describes a 65 adherent through 100 cycles. The Ni-35Cr-6A1-0.95Y 
and Ni-18Cr-12A10.3Y coatings exhibited some minor 
cracking after 100 cycles, but the Ni-16Cr-6A1-0.3Y 
coating had no apparent cracking on the major surfaces 
MCrAlY overlay coatings have been developed for 35 
nium alloys and titanium-alloy-matrix composites. 
BACKGROUNDART 
Gupta et al U.S. Pat. No. 4,419,416 is concerned with 
an MCrAlY type overlay coating wherein M is nickel, 50 
cobalt, or mixtures thereof. In addition, the coating 
contains silicon and hafnium. The substrate may contain 
nickel, cobalt, tungsten, t i ~ u m ,  tantalum, aluminum 
and chromium. 
protective coatings whose compositions are based on 
the compositions of the substrate. The coating com- 
prises aluminum, chromium, hafnium, tantalum, yttrium 
and nickel while the substrate comprises nickel, alumi- 
num, titanium, chromium and cobalt. 
U.S. Pat. No. 4,801,513 to Duhl et al discloses a pro- 
tective coating with an MCrAlY composition. The 
coating is applied to substrates including nickel, cobalt, 
aluminum, titanium, tantalum, tungsten and chromium. 
protective NiCoCrAlY coating system which can be 
applied to a nickel base alloy. A diffusion zone may be 
included, and this zone is located between the substrate 
60 
2 
3 
5,116,690 
4 - 
after 100 cycles. The oxidative weight gains of these a thermal sprayed oxidation resistant metal coating Of 
coupons were not determined because the coupons NiCrAlY adhered to said surface of said substrate, 
were not coated on the edges or ends. said coating being substantially crack free. 
of the inven- 2. A coated article of manufacture as claimed in claim 
tion have been disclosed and described, it is contern- 5 1 wherein the coating contains about 12 w/o to 38 W/O 
w/o to 1.2 w/o yttrium, and the remainder nickel. invention without departing from the spirit of the inven- 3. A coated article of manufacture as claimed in claim 
2 wherein the coating has a thickness of about 0.002 tion or the scope of the subjoined claims. By way of example, a variety of thermal spray processes, such as inch to about o.olo inch. 
While several preferred 
plated that various modifications may be made to the chromium, about 6 w/o to 15 w/o aluminum, about 0.1 
'pray and flame 'pray* as as various 4. A coated article ofmanufacture as claimed in claim 
2 wherein the coating contains about 35 w/o Cr, about spray parameters, may be made to achieve an oxidation 
resistant overlay coating as described. 6 w/o AI, about 0.95 w/o Y and the remainder nickel. 
5. A coated article of manufacture as claimed in claim 
15 2 wherein the coating contains about 18 w/o Cr, about 
12 W/O AI, about 0.3 w/o Y and the remainder nickel. 
6. A coated article of manufacture as claimed in claim 
2 wherein the coating contains about 16 w/o Cr, about 
6 w/o Al, about 0.3 w/o Y and the remainder nickel. 
We claim: 
1. A coated article of manufacture comprising 
a substrate of a material consisting of Ti3AI + Nb 
titanium alloys alone or as a matrix Of a composite 
comprising S ic  fiber in the Ti3AI+Nb material, 
said substrate having a surface that is exposed to an * * * * *  oxidizing environment, and 20 
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Oxidation resistant coating for titanium alloys and titanium alloy matrix composites

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