U.S. patent application number 09/751237 was filed with the patent office on 2001-05-10 for method for depositing braze alloy.
Invention is credited to Hunt, Mark L., Sinatra, Raymond J., Teague, Charles J..
Application Number | 20010001042 09/751237 |
Document ID | / |
Family ID | 26735163 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010001042 |
Kind Code |
A1 |
Sinatra, Raymond J. ; et
al. |
May 10, 2001 |
Method for depositing braze alloy
Abstract
The present invention relates to a method for depositing braze
alloy on a surface of a component that will be subsequently joined
to a second component. In one form a braze alloy is sprayed by a
thermal process. The braze alloy is sprayed in such a fashion that
substantially all of the powder braze alloy is unmolten, but is
heated to a state deformable enough to bond to the surface. One
form of the spraying operation utilizes a High Velocity Oxygen Fuel
spray gun.
Inventors: |
Sinatra, Raymond J.;
(Indianapolis, IN) ; Hunt, Mark L.; (Hilliard,
OH) ; Teague, Charles J.; (Indianapolis, IN) |
Correspondence
Address: |
Woodard, Emhardt, Naughton, Moriarty and McNett
Bank One Center/Tower
111 Monument Circle, Suite 3700
Indianapolis
IN
46204-5137
US
|
Family ID: |
26735163 |
Appl. No.: |
09/751237 |
Filed: |
December 29, 2000 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09751237 |
Dec 29, 2000 |
|
|
|
09375153 |
Aug 16, 1999 |
|
|
|
09375153 |
Aug 16, 1999 |
|
|
|
09056260 |
Apr 7, 1998 |
|
|
|
Current U.S.
Class: |
427/455 ;
427/446 |
Current CPC
Class: |
C23C 4/129 20160101;
C23C 4/08 20130101; C23C 4/00 20130101 |
Class at
Publication: |
427/455 ;
427/446 |
International
Class: |
C23C 004/12; C23C
004/08 |
Claims
What is claimed is:
1. A method comprising: providing a powder braze alloy; and
thermally spraying the powder braze alloy and onto a surface in
such a state that substantially all the powder braze alloy is
unmolten but is heated to a state deformable enough to bond to the
surface.
2. The method of claim 1, wherein said spraying is a High Velocity
Oxygen Fuel process, and wherein said spraying preplaces the braze
alloy on the surface.
3. The method of claim 2, wherein the High Velocity Oxygen Fuel
process utilizes H.sub.2 as its fuel.
4. The method of claim 3, wherein the spray distance is about 9
inches.
5. The method of claim 4, which further includes roughening and
degreasing the surface.
6. The method of claim 4, wherein the braze alloy is a nickel super
alloy.
7. The method of claim 4, wherein the melting point suppressant is
boron.
8. The method of claim 6, wherein the melting point suppressant is
boron.
9. The method of claim 8, which further comprises preheating the
surface to a temperature of at least 150 degrees Fahrenheit.
10. The method of claim 9, wherein the High Velocity Oxygen Fuel
process utilizes a Diamond Jet 2600 spray gun.
11. The method of claim 10, wherein the spray gun utilizes a powder
feed rate of about 5 pounds per hour.
12. The method of claim 11, wherein the flame velocity is about
4,000 ft./sec.
13. The method of claim 1, wherein: said spraying is a High
Velocity Oxygen Fuel process utilizing H.sub.2 as a fuel; said
spraying preplaces the braze alloy on the surface; said providing
includes a nickel super alloy as the braze alloy and boron as the
melting point suppressant; and which further comprises preheating
the surface to a temperature of at least 150 degrees
Fahrenheit.
14. The method of claim 2, wherein the High Velocity Oxygen Fuel
process utilizes a neutral flame.
15. The method of claim 2, wherein the High Velocity Oxygen Fuel
process utilizes a fuel rich flame.
16. The method of claim 13, wherein the High Velocity Oxygen Fuel
process utilizes a neutral flame.
17. The method of claim 13, wherein the High Velocity Oxygen Fuel
process utilizes a fuel rich flame.
18. A method comprising: providing a powder braze alloy; and
thermally spraying the powder braze alloy at a high velocity onto a
surface in such a state that substantially all the powder braze
alloy is unmolten but is heated to a state malleable enough to bond
to the surface.
19. The method of claim 18, wherein said spraying is a High
Velocity Oxygen Fuel process, and wherein said spraying preplaces
the braze alloy on the surface.
20. The method of claim 19, wherein the High Velocity Oxygen Fuel
process has H.sub.2 as its fuel.
21. The method of claim 20, wherein the velocity of the powder is
about 1,200 ft./sec. to 1600 ft/sec.
22. The method of claim 21, wherein the carrier gas is N.sub.2.
23. The method of claim 21, wherein the spray distance is about 9
inches.
24. The method of claim 23, which further includes roughening and
degreasing the surface.
25. The method of claim 23, wherein the braze alloy is a nickel
super alloy.
26. The method of claim 23, wherein the melting point suppressant
is boron.
27. The method of claim 25, wherein the melting point suppressant
is boron.
28. The method of claim 26, which further comprises preheating the
surface to a temperature of at least 150 degrees Fahrenheit.
29. The method of claim 27, wherein the High Velocity Oxygen Fuel
process utilizes a Diamond Jet 2600 spray gun.
30. The method of claim 28, wherein the spray gun utilizes a powder
feed rate of about 5 pounds per hour.
31. The method of claim 18, wherein: said spraying is a High
Velocity Oxygen Fuel process utilizing H.sub.2 as a fuel; said
spraying preplaces the braze alloy on the surface; said providing
includes a nickel super alloy as the braze alloy; and which further
comprises preheating the surface to a temperature of at least 150
degrees Fahrenheit.
32. A method comprising: providing a powder braze alloy; and flame
spraying the powder braze alloy at a high velocity onto a surface
in such a state that substantially all the powder braze alloy is
unmolten but is heated to a state malleable enough to bond to the
surface.
33. The method of claim 32, wherein said flame spraying utilizes a
neutral flame.
34. The method of claim 33, wherein said flame spraying is a High
Velocity Oxygen Fuel process, and wherein said spraying preplaces
the powder braze alloy on the surface.
35. The method of claim 34, wherein the High Velocity Oxygen Fuel
process utilizes H.sub.2 as its fuel.
36. The method of claim 35, wherein the flame velocity is about
4,000 ft./sec.
37. The method of claim 36, wherein the carrier gas is N.sub.2.
38. The method of claim 36, wherein the spray distance is about 9
inches.
39. The method of claim 38, which further includes the steps of
roughening and degreasing the surface.
40. The method of claim 38, wherein the braze alloy is a nickel
super alloy.
41. The method of claim 38, wherein the melting point suppressant
is boron.
42. The method of claim 40, wherein the melting point suppressant
is boron.
43. The method of claim 42, which further comprises preheating the
surface to a temperature of at least 150 degrees Fahrenheit.
44. The method of claim 43, wherein the High Velocity Oxygen Fuel
process utilizes a Diamond Jet 2600 spray gun.
45. The method of claim 44, wherein the spray gun utilizes a powder
feed rate of about 5 pounds per hour.
46. The method of claim 32, wherein said flame spraying utilizes a
fuel rich flame.
47. The method of claim 46, wherein said flame spraying is a High
Velocity Oxygen Fuel process, and wherein said spraying preplaces
the powder braze alloy on the surface.
48. The method of claim 47, wherein the High Velocity Oxygen Fuel
process utilizes H.sub.2 as its fuel.
49. The method of claim 48, wherein the velocity of the powder is
about 1,200 ft./sec. to 1,600 ft./sec.
50. The method of claim 49, wherein the carrier gas is N.sub.2.
51. The method of claim 49, wherein the spray distance is about 9
inches.
52. The method of claim 51, which further includes the steps of
roughening and degreasing the surface.
53. The method of claim 51, wherein the braze alloy is a nickel
super alloy.
54. The method of claim 51, wherein the melting point suppressant
is boron.
55. The method of claim 53, wherein the melting point suppressant
is boron.
56. The method of claim 55, which further comprises preheating the
surface to a temperature of at least 150 degrees Fahrenheit.
57. The method of claim 56, wherein the High Velocity Oxygen Fuel
process utilizes a Diamond Jet 2600 spray gun.
58. The method of claim 57, wherein the spray gun utilizes a powder
feed rate of about 5 pounds per hour.
59. The method of claim 32, wherein: said flame spraying is a High
Velocity Oxygen Fuel process utilizing H.sub.2 as a fuel; said
flame spraying utilizes a neutral flame; said flame spraying
preplaces the braze alloy on the surface; said providing includes a
nickel super alloy as the braze alloy; and which further comprises
preheating the surface to a temperature of at least 150 degrees
Fahrenheit.
60. The method of claim 32, wherein: said flame spraying is a High
Velocity Oxygen Fuel process utilizing H.sub.2 as a fuel; said
flame spraying utilizes a fuel rich flame; said flame spraying
preplaces the braze alloy on the surface; said providing includes a
nickel super alloy as the braze alloy; and which further comprises
preheating the surface to a temperature of at least 150 degrees
Fahrenheit.
Description
BACKGROUND OF THE INVENTION
1. The present invention relates in general to the braze joining of
metal components with a braze alloy. More particularly, one
embodiment of the present invention relates to the thermal
spraying, of a nickel braze alloy on surfaces of metallic
components that will subsequently be joined together. While one
embodiment of the present invention was developed for the
manufacture of gas turbine engine components, certain applications
may be outside of this field.
2. It is generally well known that a high temperature causing the
brazing alloy to completely melt will produce on the depositing
surface a resistant oxide membrane, which renders the surface less
brazeable. Thus, the resistant oxide membrane will limit the
effectiveness of the brazing agent layer to join two metal
components together. In the case of thermal spraying of the brazing
agent at extremely high temperatures, a considerable amount of the
brazing agent may evaporate thereby creating difficulties in
achieving uniformity in coating deposition. Further, certain
brazing agents contain brazing alloy that may pre-react during or
after melt deposition on the target surface. This pre-reaction of
braze alloy elements impairs the subsequent braze joining, of the
metal components.
3. Methods are generally known to produce brazeable aluminum
components using aluminum-silicon, aluminum-zinc, and
aluminum-silicon-zinc alloys. The prior methods were often
multi-step processes that deposited the alloy in a molten or
semi-molten state, while delivering the flux emulsion in a separate
spray. Further, the prior deposition methods generally recommend
spraying the brazing agent in a non-oxidizing atmosphere such as
N.sub.2 gas, and required extensive surface preparation prior to
deposition. Additionally, lower spray velocities previously used
were not very effective. When the particles struck the surface at
slower speeds they tended to peel away even though they were
softened by the heating and quenched by contact with the base
material surface.
4. In one particular method an aluminum-brazing agent was delivered
by plasma arc spraying. A number of difficulties occurred including
that the high temperatures associated with plasma arc spraying
pre-reacted the fluxing agent. The high temperatures causing the
aluminum alloy to be in a molten state produced on the surface a
resistant oxide membrane, which renders the material less
brazeable. There were also difficulties in achieving uniformity of
deposition due to evaporation of the thermally sprayed alloy at
such high temperatures.
5. Prior methods of joining components together by brazing have
included placing the braze alloy with a tape/powder/prewet
technique. This method has a litany of limitations that include
limitations on the component geometry, long prewet time, and
surface preparation that generally required grit blasting.
6. Although the prior methods of depositing braze alloys and braze
joining are steps in the right direction, the need for additional
improvements still remains. The present invention satisfies this
need in a novel and unobvious way.
SUMMARY OF THE INVENTION
7. One form of the present invention contemplates a method for
depositing a braze alloy. The method comprising: thermally spraying
a powder braze alloy onto a surface. The powder braze alloy is in
such a state that substantially all of the powder braze alloy is
unmolten but is heated to a state deformable enough to bond to the
surface.
8. Another form of the present invention contemplates a method for
depositing braze alloy, comprising: thermally spraying a powder
braze alloy at a high velocity onto a surface in such a state that
substantially all the powder braze alloy is unmolten, but is heated
to a state malleable enough to bond to the surface.
9. Another form of the present invention contemplates a method for
depositing braze alloy, comprising; flame spraying a powder braze
alloy at a high velocity onto a surface. The flame spraying occurs
with a stoichiometrically neutral or fuel rich flame. The flame
spraying process is such that the powder braze alloy is in such a
state that substantially all the powder braze alloy is unmolten but
is heated to a state malleable enough to bond to the surface.
10. One object of the present invention is to provide an improved
technique to apply braze alloy to components for subsequent
joining.
11. Related objects and advantages of the present invention will be
apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
12. FIG. 1 is an illustrative view of a gas turbine engine.
13. FIG. 2 is a perspective view of a gas turbine engine airfoil,
comprising a portion of FIG. 1.
14. FIG. 3 is a diagrammatic view of one form of the present
invention comprising a High Velocity Oxygen Fuel (HVOF) spray
process.
15. FIG. 4a is a view of a braze alloy deposited by a
tape/powder/prewet on a surface.
16. FIG. 4b is a view of a braze alloy applied with one form of the
High Velocity Oxygen Fuel spray process of FIG. 3.
17. FIG. 5a is a view of a braze joint created with the prior art
tape/powder/prewet applied braze alloy.
18. FIG. 5b is a view of a braze joint created with HVOF preplaced
braze alloy.
DESCRIPTION OF THE PREFERRED EMBODIMENT
19. For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiment illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended, such alterations and further modifications in the
illustrated device, and such further applications of the principles
of the invention as illustrated therein being contemplated as would
normally occur to one skilled in the art to which the invention
relates.
20. Referring the FIGS. 1 and 2, there is illustrated a gas turbine
engine 20 which includes a compressor 21, a combustor 22, and a
power turbine 23. The three components have been integrated
together to produce an aircraft flight propulsion engine. The term
aircraft is generic and includes helicopters, airplanes, missiles,
unmanned spaced devices and any other substantially similar
devices. It is important to realize that there are a multitude of
ways in which the gas turbine engine components can be linked
together. Additional compressors and turbines can be added with
intercoolers connecting between the compressors and reheat
combustion chambers could be added between the turbines.
21. Further, the gas turbine engine is equally suited to be used
for an industrial application. Historically, there has been
widespread application of industrial gas turbine engines, such as
pumping sets for gas and oil transmission lines, electricity
generation, and naval propulsion. A plurality of turbine blades 24
are coupled to a rotor disk that is affixed to a shaft rotatable
within the gas turbine engine 20. A plurality of vanes 25 are
conventionally joined together to collectively form a complete
360.degree. nozzle. It is understood herein that gas turbine engine
blades and/or vanes are often referred to as airfoils. Other
products utilizing the present invention are contemplated herein
including but not limited to combustion liners, exhaust nozzles,
exhaust liners, airframe wing leading edges and/or other fabricated
components. One form of the present invention allows the joining of
dissimilar metals with a braze alloy that is compatible with
complimenting metallurgical structures. An alternate form of the
present invention allows the braze joining of similar metals with a
braze alloy.
22. Referring to FIG. 3, a thermal coating spraying apparatus 30 is
positioned relative to a base material 40 for delivering a coating
41 of braze alloy material thereon. In the preferred embodiment,
the spraying apparatus 30 is a HVOF (High Velocity Oxygen Fuel)
spray gun. It is well known that a HVOF process is a flame spray
coating deposition process that can apply a dense, very low
porosity coatings. The controlled BTU output and high gas velocity
imparts both thermal and kinetic energy to the powder braze alloy
particles. One spraying apparatus of this type is disclosed in U.S.
Pat. No. 4,999,225 to Rotolico incorporated herein by reference,
and is available from the Perkin Elmer Corporation of Norwolk,
Conn. Other HVOF spraying apparatuses of this general type are
available in the market place and are known to those of ordinary
skill in the art. In a preferred embodiment the Diamond Jet HVOF
spray gun, manufactured by Sulzer Metco (US) Inc., with the DJ 2600
hybrid air/water cooled air cap assembly enhancement package that
produces higher spray velocities than the standard Diamond Jet
hardware is utilized. The DJ 2600 is intended for use only with
hydrogen as the fuel gas to produce premium quality HVOF coatings.
The DJ 2600 option provides the Diamond Jet spray gun with gas
velocities of up to 7000 ft/sec whereas gas velocities typically
approach 4500 ft/sec on the standard Diamond Jet spray gun.
However, the present invention is not intended to be limited to the
use of this particular spray gun. The use of other HVOF spray guns
is contemplated herein.
23. The thermal spraying process associated with HVOF guns heats
and/or melts ceramic or metal stock/powder coating. The powder or
stock is then fed through the center of the HVOF gun 30 and the
heated coating material is carried by the high velocity fluid
stream to the surface for deposition. In a preferred embodiment,
the HVOF process delivers the heated coating material particles 45
to the base surface material 40 at supersonic speed. Delivery of
the heated coating material particles 45 to the base material
surface 40 at supersonic speeds creates a mechanical interlock
between the base surface material 40 and the sprayed coating
material 41. It is preferred that the heated material be delivered
at speeds equal to Mach 2 or greater. However, in an alternate
embodiment, the delivery of the coating material occurs at speeds
that are about equal to the speed of sound.
24. The high velocity of the malleable impinging particle spray 45
onto the base material 40 produces a dense, uniform, low porosity
coating 41. The braze alloy coatings applicable for base material
braze joining include a wide variety of materials. The following
coatings and base materials, however, have been found to provide
preferred results in conjunction with the HVOF conditions discussed
below.
25. One preferred embodiment is the deposition of braze alloy Amdry
DF-4B onto base metal AF2-1DA-6. A more preferred embodiment is the
deposition of Amdry BRB braze alloy onto base metal AF2-1DA-6. It
is understood herein that other braze alloys such as nickel or
cobalt superalloys may be deposited using this method as long as
they are homogenous compounds. The DF-4B braze alloy composition
is: 14Cr, Bal.Ni, 10Co, 3.5Al, 2.75B, 2.5Ta, 0.02Y. The AF2-IDA-6
base metal composition is: 12Cr, Bal.Ni, 10Co, 2.75Mo, 6.7W, 2.8Ti,
4.6Al, 0.015B, 0.0Zr, 1.5Ta. The Amdry BRB braze alloy composition
is: 13.5Cr, Bal.Ni, 9.5Co, 4.0Al, 2.5B, 0.1Y. With these powder
braze alloys, the following parameters were developed for the HVOF
system to utilize a neutral or fuel rich flame condition to retard
the pre-reaction of braze with base material. All flow rates have
units of S.C.F.H. (standard cubic feet hour). The fuel used in the
Diamond Jet 2600 spray gun is H.sub.2. The primary gas type is
oxygen (O.sub.2) at 175 psi and primary flow of 26 S.C.F.H.
Secondary gas is H.sub.2 at 140 psi and secondary flow of 62
S.C.F.H. The airflow is 46 S.C.F.H. at 20 psi. The carrier flow was
of N.sub.2 gas at 150 psi with a carrier flow of 55 S.C.F.H. The
spray powder was fed into the gun at a rate of 5 lbs./hr. Referring
to FIG. 3, the preferred spray distance 50 is about nine inches. In
another preferred embodiment, the base surface material 40 is
prepared with sixty-grit silicon carbide paper and is degreased
with Acetone.
26. In an alternative embodiment the base surface material 40 is
preheated to 150 degrees Fahrenheit. This can be accomplished by
directing the HVOF gun's flame onto the base surface material 40 to
preheat it. Upon reaching the appropriate temperature for
deposition of the selected material, the powder braze alloy is fed
through the HVOF gun. It is understood that using the HVOF gun is
one technique of preheating base surface material 40, however,
other preheating techniques, such as preheating in an oven, are
contemplated herein. The braze alloy used is homogenous. Both the
Amdry BRB and DF-4B alloy are preferably used with particle sizes
in the range of ASTM mesh size -140+325 or -106+45 microns. The
particle sizes were selected based on their superior resistances to
melting and entraining oxides therein. Additionally, particle size
affects compression during the secondary braze operation utilized
to join the metallic components together.
27. In the preferred mode the oxygen, fuel, and carrier gas
pressures and flow rates previously given result in a neutral or
slightly fuel rich flame. This type of flame retards oxidation of
the braze alloy by creating a circular flame which shapes the
powder stream and accelerates the particles to the surface.
28. In one embodiment flame velocity is about 4,000 fl/sec. and
imparts both thermal and kinetic energy to the impinging powder
braze alloy particles. In one embodiment the partical velocity
being in the range of about 1,200-1,600 ft/sec. The particles are
malleable but substantially unmolten. This results in mechanical
adhesion to the surface. Since the adhesion is mechanical, minimal
surface preparation is necessary prior to depositing the braze
alloy coating. Since the particles are not in a semi-molten
condition there is little loss or uneven distribution due to
evaporation. In this method, the braze alloy is delivered in a
single spray stream. The environment surrounding the process can be
the ambient shop floor condition and need not be a non-oxidizing or
an evacuated atmosphere.
29. Prewetting involves heating the base material and braze alloy
to a temperature that causes the braze alloy to partially melt. A
high temperature and softened braze alloy result in some of melting
point suppressants in the braze alloy diffusing into the base
material. This results in an increase in the braze alloy melting
point, which is limited by how hot a material can be taken during
brazing where the braze alloy does not react the same due to the
loss of certain elements.
30. In contrast to the tape/powder/prewet cycle, there is no
substantial loss of braze alloy potential due to diffusion. This
results in both better braze flow and wettability as well as better
joint filling capability. Additionally there are time and cost
savings in part preparation and vacuum furnace operation by using
the HVOF spraying process instead of the labor intensive
tape/powder/prewet cycle. The braze alloy can be preplaced on
contoured and complex surfaces and the base material is not
subjected to high prewet temperatures. Thermal spraying also allows
for the possibility of applying braze alloy in patterns by masking
certain areas. Also, there is no concern of a residue of an
adhesive as in the tape/powder/prewet cycle.
31. With reference to FIG. 4a and 4b, these two photographs show
the advantages of uniformity of deposition achieved by HVOF applied
braze alloy powder in contrast to braze alloy powder deposited by
the prior art tape/powder/prewet method. FIGS. 5a and 5b show a
braze joint created with the prior art tape/powder/prewet applied
braze alloy and braze joint created with HVOF preplaced braze
alloy.
32. While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *