U.S. patent application number 15/544700 was filed with the patent office on 2018-01-04 for cold spray process using treated metal powder.
The applicant listed for this patent is Sikorsky Aircraft Corporation. Invention is credited to Zissis A. Dardas, Michael A. Klecka, Randolph Carlton McGee, Aaron T. Nardi, Ying She.
Application Number | 20180002815 15/544700 |
Document ID | / |
Family ID | 56417666 |
Filed Date | 2018-01-04 |
United States Patent
Application |
20180002815 |
Kind Code |
A1 |
McGee; Randolph Carlton ; et
al. |
January 4, 2018 |
COLD SPRAY PROCESS USING TREATED METAL POWDER
Abstract
A method of applying a metal comprising titanium to a substrate
is disclosed. The method comprises nitriding the surface of metal
powder particles comprising titanium by contacting the particles
with a first gas comprising nitrogen in a fluidized bed reactor,
and depositing the metal powder particles onto the substrate with
cold spray deposition using a second gas.
Inventors: |
McGee; Randolph Carlton;
(Hamden, CT) ; Dardas; Zissis A.; (Bethany,
MA) ; She; Ying; (East Hartford, CT) ; Nardi;
Aaron T.; (East Granby, CT) ; Klecka; Michael A.;
(Coventry, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sikorsky Aircraft Corporation |
Stratford |
CT |
US |
|
|
Family ID: |
56417666 |
Appl. No.: |
15/544700 |
Filed: |
January 20, 2016 |
PCT Filed: |
January 20, 2016 |
PCT NO: |
PCT/US2016/013995 |
371 Date: |
July 19, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62106140 |
Jan 21, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 8/24 20130101; B22F
1/0088 20130101; C23C 8/80 20130101; C23C 24/04 20130101; C22C
29/16 20130101 |
International
Class: |
C23C 24/04 20060101
C23C024/04; C23C 8/24 20060101 C23C008/24; B22F 1/00 20060101
B22F001/00 |
Claims
1. A method of applying a metal comprising titanium to a substrate,
the method comprising: nitriding the surface of metal powder
particles comprising titanium by contacting the particles with a
first gas comprising nitrogen in a fluidized bed reactor; and
depositing the metal powder particles onto the substrate with cold
spray deposition using a second gas.
2. The method of claim 1, wherein the metal powder particles
comprise at least one titanium or titanium alloy selected from
grades 5 (Ti--6Al--4V) and 23 (Ti--6Al--4V), according to ASTM
B861-10.
3. The method of claim 2, wherein the metal powder particles
comprise at least one titanium or titanium alloy selected from
Ti--6Al--4V, Ti--3Al--2.5V, Ti--5Al--2.5Sn, Ti--8Al--1Mo--1V,
Ti--6Al--2Sn--4Zr--2Mo, .alpha.+.beta. Ti--6Al--4V, and near .beta.
Ti--10V--2Fe--3Al.
4. The method of claim 1, wherein the metal powder particles after
nitriding comprise nitrogen at the particle surface and also
comprise an internal particle portion that is free of nitrogen.
5. The method of claim 1, wherein the metal powder particles after
nitriding have a surface nitrogen content ranging from 5.96 wt. %
to 12.22 wt. % as determined by x-ray photoelectron
spectroscopy.
6. The method of claim 1, wherein the metal powder particles after
nitriding have a nitrogen:oxygen surface wt. % ratio of from
5.96:26.2 to 12.26:16.75 as determined by x-ray photoelectron
spectroscopy.
7. The method of claim 1, wherein the first gas comprises at least
1 vol. % nitrogen.
8. The method of claim 1, wherein the first gas consists
essentially of nitrogen.
9. The method of claim 1, wherein the fluidized bed reactor is
operated at a temperature of 500.degree. C. to 850.degree. C.
10. The method of claim 1, wherein the first gas is at a pressure
of 0.11 to 0.12 MPa.
11. The method of claim 1, wherein the space velocity of the first
gas in the fluidized bed reactor is from 1 min.sup.-1 to 30
min.sup.-1.
12. The method of claim 1, wherein the metal powder particles are
contacted with the first gas in the fluidized bed reactor for at
least 1 minute.
13. The method of claim 1, wherein the second gas comprises
helium.
14. The method of claim 13, wherein the second gas further
comprises nitrogen.
15. The method of claim 13, wherein the second gas consists
essentially of helium.
16. The method of claim 1, wherein the second gas is at a
temperature of 20.degree. C. to 850.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] Thermal spray technologies such as the cold spray process
can be used for various applications such as applying metal layers
to non-metallic substrates to make metal layer-containing composite
articles, applying metal outer layers to substrates of a different
material, for example to obtain corrosion benefits of the outer
layer metal with the processability of the substrate metal, field
repair of metal components, and various other additive
manufacturing technology applications.
[0002] Titanium and titanium alloys are widely used for various
applications such as aircraft, motor vehicles, and countless other
applications, where they provide beneficial properties including
but not limited to strength, strength:weight ratio, corrosion
resistance, high specific heat, and tolerance of extreme
temperatures. However, the use of titanium alloys as metal powder
used in the cold spray process has been limited by factors such as
degradation of the nozzles used in the cold gas spray process and a
tendency of the titanium alloys to clog nozzles used in the cold
spray process. Conventional approaches for dealing with such nozzle
problems typically involve the use of exotic (and expensive)
materials such as quartz for the cold spray nozzles, or
modification of cold spray process parameters to lower temperatures
or other process modifications that can cause adverse impacts to
the properties of cold spray-applied material.
BRIEF DESCRIPTION OF THE INVENTION
[0003] According the invention, there is a method of applying a
metal comprising titanium to a substrate. The method comprises
nitriding the surface of metal powder particles comprising titanium
by contacting the particles with a first gas comprising nitrogen in
a fluidized bed reactor, and depositing the nitrided metal powder
particles onto the substrate with cold spray deposition using a
second gas.
[0004] In some aspects of the invention, the metal powder particles
comprise titanium or titanium alloys Ti--6Al--4V, Ti--3Al--2.5V,
Ti--5Al--2.5Sn, Ti--8Al--1Mo--1V, Ti--6Al--2Sn--4Zr--2Mo,
.alpha.+.beta. Ti--6Al--4V, or near .beta. Ti--10V--2Fe--3Al.
[0005] In some aspects of the invention, the metal powder particles
comprises titanium or titanium alloy grades 5 (Ti--6Al--4V) or 23
(Ti--6Al--4V) according to ASTM B861-10.
[0006] In some aspects of the invention, the metal powder particles
after nitriding comprise elemental nitrogen at the particle surface
and also comprise an internal particle portion that is free of
elemental nitrogen.
[0007] In some aspects of the invention, the metal powder particles
after nitriding have a surface nitrogen content ranging from 5.96
wt. % to 12.22 wt. % as determined by x-ray photoelectron
spectroscopy.
[0008] In some aspects of the invention, the metal powder particles
after nitriding have a nitrogen:oxygen surface wt. % ratio of from
5.96:26.20 to 12.22:16.75 as determined by x-ray photoelectron
spectroscopy.
[0009] In some aspects of the invention, the first gas comprises at
least 1 vol. % nitrogen.
[0010] In some aspects of the invention, the first gas consists
essentially of nitrogen.
[0011] In some aspects of the invention, the fluidized bed reactor
is operated at a temperature of 500.degree. C. to 850.degree.
C.
[0012] In some aspects of the invention, the first gas is at a
pressure of 0.11 to 0.12 MPa.
[0013] In some aspects of the invention, the space velocity of the
first gas in the fluidized bed reactor is from 1 min.sup.-1 to 30
min.sup.-1.
[0014] In some aspects of the invention, the metal powder particles
are contacted with the first gas in the fluidized bed reactor for
at least 1 minute.
[0015] In some aspects of the invention, the second gas comprises
helium or argon.
[0016] In some aspects of the invention, the second gas comprises
helium or argon and nitrogen.
[0017] In some aspects of the invention, the second gas consists
essentially of helium or argon.
[0018] In some aspects of the invention, the second gas is at a
temperature of 20.degree. C. to 850.degree. C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying figures, in which:
[0020] FIG. 1 is a schematic depiction of a fluidized bed reactor
assembly;
[0021] FIG. 2 is a schematic depiction of a cold spray system;
and
[0022] FIG. 3 is a bar chart showing the results of surface
elemental analysis of titanium alloy powders processed as described
herein.
DETAILED DESCRIPTION OF THE INVENTION
[0023] An exemplary fluidized bed reactor assembly for nitriding
titanium alloys is depicted in FIG. 1. As shown in FIG. 1, the
assembly includes a fluidized bed reactor 12 having inlet openings
14 disposed at one end of the reactor 12 and an outlet opening 16
disposed at the opposite end of the reactor 12. The fluidized bed
reactor 12 is disposed inside of an outer tubing 18, with outlet 16
extending to the outside of outer tubing 18. During operation, the
fluidized bed assembly is disposed in a furnace (not shown) to
provide heat. Thermocouples 17 and 19 are disposed to monitor
temperature in the reactor 12 and outer tubing 18, respectively. An
inlet 20 is connected to a gas feed line 22. A gas source 24 such
as a storage tank or a gas-generating reactor is connected to gas
feed line 22 to supply a gas feed to the fluidized bed reactor 12.
Other components, such as mass flow controller 26, pressure
regulating valve 28, pressure sensor 30, and shut-off valves 32 and
34 are also disposed in the gas feed line 22 for monitoring and
controlling the flow rate and pressure of the gas delivered to the
reactor 12. Reactor outlet 16 is connected to outlet line 36, which
is connected to a water or other liquid bubbler 38. A bleed line 40
with shut-off valve 42 also connects feed line 22 to the bubbler
38, which is vented to atmosphere through exhaust port 44.
[0024] In operation, a gas comprising nitrogen from gas source 24
is fed through feed line 22, with the flow rate and gas pressure
controlled by mass flow controller 26 and pressure regulating valve
28. The nitrogen-containing gas enters the outer tubing 18 through
inlet 20. The gas is heated as it passes through the space between
fluidized bed 12 and outer tubing 18 to enter the fluidized bed
reactor 12 through inlet 14. The fluidized bed reactor 12 has metal
particles 46 comprising titanium disposed therein, and the upward
gas flow rate through the reactor applies sufficient upward force
to the particles 46 to counteract the force of gravity acting on
the particles so that they are suspended in a fluid configuration
in the reactor space. The gas flow is generally maintained below
levels that would carry entrained particles out of the reactor 16
through outlet 16, and outlet 16 can also be fitted with a filter
or screen to further assist in keeping metal powder particles 46
from exiting the reactor 12. Nitrogen-containing gas exits the
reactor 12 through outlet 16 and flows via outlet line 36 to the
bubbler 38, from which it is exhausted to the atmosphere through
exhaust port 44.
[0025] The invention can utilize any titanium metal or titanium
metal alloy, including any of the grades of titanium alloys
specified in ASTM B861-10. Alpha titanium alloys, near-alpha
titanium alloys, alpha-beta titanium alloys, and beta titanium
alloys. In some embodiments, the titanium alloy comprises from 0 to
10 wt. % aluminum and from 0 to 10 wt. % vanadium. In some
embodiments, the titanium alloy is an alpha-beta titanium alloy
such as Ti--6Al--4V (e.g., grades 5 or 23 according to ASTM
B861-10), Ti--Al--Sn, Ti--Al--V--Sn, Ti--Al--Mo, Ti--Al--Nb,
Ti--V--Fe--Al, Ti--8Al--1Mo--1V, Ti--6Al--2Sn--4Zr--2Mo,
.alpha.+.beta. Ti--6Al--4V or near .beta. Ti--10V--2Fe--3Al. In
some embodiments, the titanium alloy is a Ti--6Al--4V alloy such as
grade 5 or grade 23 according to ASTM B861-10.
[0026] The nitrogen-containing gas can contain from 1 vol. % to 100
vol. % nitrogen, more specifically from 5 vol. % to 100 vol. %
nitrogen, and more specifically from 25 vol. % to 75 vol. %
nitrogen. In some embodiments, the nitrogen-containing gas consists
essentially of nitrogen, and in some embodiments the
nitrogen-containing gas is pure. The nitriding reaction conducted
in the fluidized bed reactor is typically conducted at elevated
temperature, compared to ambient conditions. The reaction
temperature in the reactor can range from 500.degree. C. to
800.degree. C., more specifically from 600.degree. C. to
750.degree. C., and even more specifically from 600.degree. C. to
700.degree. C. Pressures in the reactor can range from 0.11 MPa to
0.13 MPa, more specifically from 0.11 MPa to 0.12 MPa, and even
more specifically from 0.11 MPa to 0.115 MPa. The flow rate of
nitrogen to the reactor can vary based on factors such as reactor
dimension, with exemplary flow rates of 0.0069 m/min to 0.013
m/min, more specifically from 0.0097 m/min to 0.011 m/min, and even
more specifically from 0.010 m/min to 0.0105 m/min. The metal
powder particles can be nitrided for periods (i.e., contact time
with the nitrogen-containing gas) of at least 1 minute, for
example, time periods ranging from 1 minute to 30 minutes, more
specifically from 1 minute to 10 minutes, and even more
specifically from 1 minute to 5 minutes. In batch mode, such as
depicted in the reaction scheme shown in FIG. 1, the reactor is
operated for the specified amount of time to achieve the desired
contact time. In a continuous mode, throughput of the particles
through the reactor can be adjusted to achieve an average residence
time equal to the desired contact time.
[0027] After processing the titanium-containing metal particles in
the nitrogen-containing fluidized bed reactor, the particles can
have a surface nitrogen content ranging from 5.96 wt. % to 12.22
wt. %, more specifically from 5.96 wt. % to 7.90 wt. %, or from
7.90 wt. % to 9.77 wt. %, or from 9.77 wt. % to 12.22 wt. %, as
determined by x-ray photoelectron spectroscopy. As used herein,
x-ray photoelectron spectroscopy and the values specified herein
are according to the protocols of according to ASTM E2735-14,
Standard
[0028] Guide for Selection of Calibrations Needed for X-ray
Photoelectron Spectroscopy (XPS) Experiments, ASTM International,
West Conshohocken, Pa., 2014. Surface nitrogen on titanium or
titanium alloy metal particles can bond with titanium or other
metals in the alloy such as aluminum, and in doing so can displace
oxygen from metal oxide at the particle surface, thus reducing the
material's oxygen content at the surface. In some embodiments,
after nitriding the metal powder particles can have a
nitrogen:oxygen surface wt. % ratio of from 5.96:26.20 to
7.90:21.83 as determined by x-ray photoelectron spectroscopy, and
more specifically can have a nitrogen:oxygen surface wt. % ratio of
from 9.77:19.99 to 12.22:16.75. The use of pure titanium nitride as
a cold spray applied metal can result in undesirable porosity
levels in the applied material. Accordingly, in some embodiments,
the nitriding reaction is conducted under conditions (e.g., contact
time, temperature, space velocity) so that nitriding occurs on the
surface of the metal particles but not throughout the interior of
the particles, resulting in particles with a surface layer
comprising nitrogen and at least a portion of the particles'
interior being free of nitrogen.
[0029] As mentioned above, the nitride titanium or titanium alloy
metal powder is applied to a substrate with a cold spray deposition
process. In a cold spray process, unmelted metal particles are
introduced into a high velocity gas stream being projected out of a
high velocity (e.g., supersonic) nozzle toward the coating
substrate target. The particles' kinetic energy provides sufficient
heat on impact with the coating substrate such that the particles
plastically deform and fuse with the substrate and surrounding
deposited metal material. As the particles impact the substrate,
they rapidly cool even as the particles are deforming. The
particles change shape dramatically from relatively round to very
thin flat splats on the surface.
[0030] An exemplary system is depicted in FIG. 2. As shown in FIG.
2, metal powder is fed from powder feeder 48 through conduit 49 to
spray gun 50, which includes nozzle 52 and gun heater 54. Powder
particle diameter sizes can range from 1 to 120 microns, more
specifically from 5 to 75 microns. Pressurized gas is fed from gas
pre-heater 56 to gun heater 54 through conduit 55. Exemplary gases
for use in the system include helium, nitrogen, or a mixture of
helium and nitrogen. Helium can provide greater gas velocities than
nitrogen and has the additional technical effect of being benefited
by the nitriding process because unlike a nitrogen-based gas
stream, helium does not provide any opportunity for nitriding to
occur in the spray gun 50. The powder and the gas streams are mixed
in the gun and accelerated to supersonic speeds as the gas/powder
mixture exits the nozzle 52. The system also includes a controller
or control console 58, which receives input from gun pressure
sensor 60 and gun temperature sensor 62 and provides control
signals to the gas pre-heater and powder feeder. The term "cold" in
"cold spray deposition" refers to the fact that the gas is
maintained at a temperature below the melting point of the metal
powder; however, as described above the gas is heated in both the
gas pre-heater 56 and the gun heater 54. The temperature of the gas
used in the process can range from 0.degree. C. to 1200.degree. C.,
more specifically from 200.degree. C. to 1000.degree. C., and even
more specifically from 200.degree. C. to 800.degree. C. Gas
pressure can range from 5 bar to 60 bar, more specifically from 15
bar to 45 bar, and even more specifically from 20 bar to 40
bar.
[0031] The invention is further described in the following
Examples.
EXAMPLES
[0032] Ti--6Al--4V alloy powder materials were nitrided in a
fluidized bed reactor as shown in FIG. 1. Approximately, 25-40 g of
Ti--6Al-4-V powder, particle size of 10 to 88 microns was loaded
into the fluidized bed reactor. The reactor was then placed in a
Model K-3-18 reactor furnace (CM Furnaces, Inc.). Prior to
nitridation, argon gas (Praxair) was introduced into the reactor at
flow rates equivalent to the N.sub.2 rates to be used for
nitridation. This was done by using an MKS type 247 mass flow
controller. In each case, the furnace temperature was increased at
a rate of about 4.5.degree. C./min to the target nitridation
temperature as shown in Table 1. A control sample was also prepared
in which argon gas was used for the entire process without any
nitrogen gas.
TABLE-US-00001 TABLE 1 Temperature (.degree. C.) 700 800 N.sub.2
flow rate (ml/min) 286 260 Duration (min) 30 30
[0033] After the target temperature was reached using an argon gas
flow in the reactor, the gas flow was switched to nitrogen
(Matheson) and the temperature was held for the times indicated in
Table 1. After treating the powder samples in nitrogen at the
designated temperature and time, the gas flow was switched to argon
and the reactor was allowed to cool down. This was done primarily
to isolate the soak time and to prevent any further nitridation
that might occur at the higher temperatures during the slow cooling
process. Once the powder temperature reached a low enough
temperature (about 300.degree. C.), the gas flow was switched
again, back to nitrogen and the furnace continued to cool down to
ambient temperature. The resulting metal powders, along with
samples of the untreated powder, were characterized using scanning
electron microscopy (SEM) and energy dispersive X-ray
micro-analysis (EDX). Identification of bulk phase structures and
the extent of nitridation were conducted by X-ray diffraction (XRD)
using Rigaku and JADE software from MDI. Surface elemental
composition was determined by X-ray photoelectron spectroscopy
(XPS) using a PHI VersaProbe. Elemental surface analysis was
conducted by x-ray photoelectron spectroscopy, the results of which
are shown in FIG. 3. As shown in FIG. 3, nitridation at 700.degree.
C. and 800.degree. C. each resulted in an increase in surface
nitrogen on the particles and a decrease in surface oxygen for the
particles, with nitridation at 800.degree. C. producing a greater
effect than nitridation at 700.degree. C. Surface carbon detected
by XPS is believed to result from surface contamination during
preparation of the metal powders.
[0034] The metal powders were used in a system as shown in FIG. 2
using helium at 700.degree. and 30 bar as the gas or a 50/50 blend
of helium and nitrogen at 800.degree. C. and 40 bar. The nitrided
titanium alloy powders exhibited significantly reduced nozzle
clogging (and resulting higher quality metal deposits) than either
the untreated powder or the control powder.
[0035] As used herein: The singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates
otherwise. "Or" means "and/or." The modifier "about" used in
connection with a quantity is inclusive of the stated value and has
the meaning dictated by the context (e.g., includes the degree of
error associated with measurement of the particular quantity). The
terms "front", "back", "bottom", and/or "top" are used herein,
unless otherwise noted, merely for convenience of description, and
are not limited to any one position or spatial orientation. The
terms "first", "second", "third", and so on are used herein, unless
otherwise noted, merely for convenience of description, and are not
limited to any one ordering or order of preference. The endpoints
of all ranges directed to the same component or property are
inclusive and independently combinable (e.g., ranges of "less than
or equal to 25 wt %, or 5 wt % to 20 wt %," is inclusive of the
endpoints and all intermediate values of the ranges of "5 wt % to
25 wt %," etc.). The suffix "(s)" is intended to include both the
singular and the plural of the term that it modifies, thereby
including at least one of that term (e.g., the colorant(s) includes
at least one colorants). "Optional" or "optionally" means that the
subsequently described event or circumstance can or can not occur,
and that the description includes instances where the event occurs
and instances where it does not. Unless defined otherwise,
technical and scientific terms used herein have the same meaning as
is commonly understood by one of skill in the art to which this
invention belongs.
[0036] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *