U.S. patent application number 10/740452 was filed with the patent office on 2005-06-23 for chrome composite materials.
Invention is credited to Beardsley, M. Brad, Jiang, Xiangyang, Smith, William C..
Application Number | 20050132843 10/740452 |
Document ID | / |
Family ID | 34677878 |
Filed Date | 2005-06-23 |
United States Patent
Application |
20050132843 |
Kind Code |
A1 |
Jiang, Xiangyang ; et
al. |
June 23, 2005 |
Chrome composite materials
Abstract
A method of making a composite chrome powder is provided. The
method includes selecting a ferrochrome material. The ferrochrome
material is mixed together with a nickel-based material, and a
composite chrome powder is generated from the mixture.
Inventors: |
Jiang, Xiangyang; (Dunlap,
IL) ; Beardsley, M. Brad; (Laura, IL) ; Smith,
William C.; (Chillicothe, IL) |
Correspondence
Address: |
Finnegan, Henderson, Farabow,
Garrett & Dunner, L.L.P.
1300 I Street, N.W.
Washington
DC
20005-3315
US
|
Family ID: |
34677878 |
Appl. No.: |
10/740452 |
Filed: |
December 22, 2003 |
Current U.S.
Class: |
75/252 ; 427/450;
428/570 |
Current CPC
Class: |
C23C 4/06 20130101; C22C
29/067 20130101; B22F 2999/00 20130101; B22F 2999/00 20130101; C22C
1/051 20130101; B22F 2999/00 20130101; B22F 1/025 20130101; Y10T
428/12181 20150115; B22F 9/026 20130101; B22F 1/025 20130101; B22F
9/04 20130101; B22F 1/025 20130101; B22F 9/305 20130101 |
Class at
Publication: |
075/252 ;
428/570; 427/450 |
International
Class: |
C22C 029/06 |
Claims
1-14. (canceled)
15. A chrome composite powder, comprising: a high carbon
ferrochrome component; a nickel-based component; and at least one
of activated carbon and graphite powder.
16. The composite powder of claim 15, wherein the high carbon
ferrochrome component contains iron up to about 65% by weight.
17. The composite powder of claim 15, wherein the high carbon
ferrochrome component contains carbon up to about 14% by
weight.
18. The composite powder of claim 15, wherein the high carbon
ferrochrome component has a chrome content of about 15 percent by
weight to about 75 percent by weight.
19. The composite powder of claim 15, wherein the high carbon
ferrochrome component has an iron content less than about 35% by
weight.
20. The composite powder of claim 15, wherein the high carbon
ferrochrome component has a total weight percentage of no more than
about 5 percent by weight provided by one or more of the following
elements: silicon, titanium, niobium, vanadium, tantalum,
molybdenum, tungsten, and manganese.
21-24. (canceled)
25. A chrome composite powder, comprising: a plurality of
particles, wherein at least some of the particles include: a
carbide-metal matrix composite structure having: a matrix material
including at least one of nickel, nickel-chromium, and iron chrome;
and a plurality of Fe--Cr-carbide particles dispersed in the matrix
material; wherein the Fe--Cr particles include at least one of
(CrFe).sub.7C.sub.3, (CrFe).sub.23C.sub.6, and
(CrFe).sub.3C.sub.2.
26. A chrome composite powder, comprising: a plurality of
particles, wherein at least some of the particles include: a
ferrochrome core material; and at least one of a nickel layer and a
nickel-chromium layer clad on the ferrochrome core material wherein
the ferrochrome core material includes at least one of
(CrFe.sub.7C.sub.3, (CrFe).sub.23C.sub.6, and
(CrFe).sub.3C.sub.2.
27. A composite material, comprising: a nickel-based component; a
ferrochrome component dispersed within the nickel-based component;
and at least one of activated carbon and graphite.
28. The composite material of claim 27, wherein the ferrochrome
component contains iron up to about 35 percent by weight.
29. (canceled)
30. The composite material of claim 27, wherein the ferrochrome
component contains carbon up to about 14 percent by weight.
31. The composite material of claim 27, wherein the ferrochrome
component has a chrome content of between about 15% and about 75%
by weight.
32. The composite material of claim 27, further including no more
than about 5 percent by weight provided by any one of silicon,
titanium, niobium, vanadium, tantalum, molybdenum, tungsten, and
manganese.
33. The composite material of claim 27, further including no more
than about 10 percent by weight provided by any combination of
silicon, titanium, niobium, vanadium, tantalum, molybdenum,
tungsten, and manganese.
34. A composite material comprising: a nickel-based material
forming a nickel matrix; and a plurality of carbon ferrochrome
particles dispersed in the nickel matrix; wherein at least some of
the carbon ferrochrome particles include at least one of
(CrFe).sub.7C.sub.3, (CrFe).sub.23C.sub.6, and
(CrFe).sub.3C.sub.2.
35. The composite material of claim 34, wherein the composite
material has a Knoop hardness value of between about 950 to 1200
HK.
36. The composite material of claim 34, wherein the plurality of
carbon ferrochrome particles dispersed in the nickel matrix are
disposed as a coating on a substrate material.
37. The composite material of claim 36, wherein the substrate
material includes an engine component.
38. The composite material of claim 36, wherein the substrate
material includes a bearing.
39. A composite material comprising: a nickel-based material
forming a nickel matrix, and a plurality of carbon ferrochrome
particles dispersed in the nickel matrix; wherein the plurality of
carbon ferrochrome particles dispersed in the nickel matrix are
disposed as a coating on a substrate material, and the substrate
material includes an axle.
40. A method of forming a coating on a substrate, the method
comprising: mixing a ferrochrome material with a nickel-based
material to form a mixture; generating a composite chrome powder
from the mixture; supplying the composite chrome powder to a
coating apparatus; and forming a chrome-including composite
material coating on at least one surface of the substrate; wherein
the ferrochrome material includes at least one of
(CrFe).sub.7C.sub.3, (CrFe).sub.23C.sub.6, and
(CrFe).sub.3C.sub.2.
41. The method of claim 40, wherein the coating apparatus includes
a high velocity oxy-fuel (HVOF) system.
42. The method of claim 40, wherein the coating apparatus includes
a detonation spray system.
43. The method of claim 40, wherein the chrome-including composite
material coating has a Knoop hardness value of between about 950 to
1200 HK.
44. The method of claim 40, wherein the substrate includes an
engine component.
45. The method of claim 40, wherein the substrate includes a
bearing.
46. A method of forming a coating on a substrate, the method
comprising: mixing a ferrochrome material with a nickel-based
material to form a mixture; generating a composite chrome powder
from the mixture; supplying the composite chrome powder to a
coating apparatus; and forming a chrome-including composite
material coating on at least one surface of the substrate; wherein
the substrate includes an axle.
47. (canceled)
48. The method of claim 40, wherein the ferrochrome material has an
iron to chrome weight ratio of from about 0.2 to 0.5 by weight and
a carbon to chrome ratio of from about 0 to 0.2 by weight.
49. The method of claim 40, wherein the chrome-including composite
material coating includes a plurality of ferrochrome particles
dispersed in a nickel matrix.
Description
TECHNICAL FIELD
[0001] This invention relates generally to chrome composite powders
and methods for producing the chrome composite powders.
BACKGROUND
[0002] Wear and corrosion resistant materials are of great interest
to many industries, including, but not limited to, the heavy
machinery, automobile, and aerospace industries. Even as demand
increases for complex machined components with long life/duty
cycles, low maintenance requirements, and improved performance
under harsh conditions, a parallel objective exists to achieve
these ends at reduced cost to both the industry and the consumer.
Achieving satisfactory wear and corrosion resistance in today's
complex materials has typically required the use of relatively
expensive starting/raw materials in combination with lengthy and
complex processing techniques. While this route can produce wear
and corrosion resistant materials, it can be costly.
[0003] For example, chrome carbide types of powders, such as
Cr.sub.3C.sub.2 or Cr.sub.7C.sub.3 are widely used in applications
for wear and corrosion resistant coatings, as disclosed in U.S.
Pat. No. 6,254,704,. These Cr.sub.3C.sub.2 or Cr.sub.7C.sub.3
containing powders are typically made by combining pure, high
carbon content precursors, which may be high cost materials, with a
nickel material. The resulting chromium carbide materials may be
used to generate the chrome carbide powders. A disadvantage of this
process is that the resulting chrome carbide powders are costly.
The high cost of the chrome carbide powders may be due to the use
of expensive high carbon content chrome carbide precursor
materials, which are generally produced only on small scales for
specialty applications.
[0004] Using known processing techniques, these high cost chrome
carbide powders may be used to produce wear and corrosion resistant
materials such as, for example, complex chrome composite powders
and coatings. While these materials may offer suitable performance,
their substantial cost of production may be prohibitive for many
applications.
[0005] The invention is directed to overcoming one or more of the
problems or disadvantages existing in the prior art.
SUMMARY OF THE INVENTION
[0006] One aspect of the invention includes a method of making a
composite chrome powder. The method includes selecting a
ferrochrome material. The ferrochrome material is mixed together
with a nickel-based material, and a composite chrome powder is
generated from the mixture.
[0007] A second aspect of the invention includes a chrome composite
powder. The composite powder includes a plurality of particles,
wherein at least some of the particles include a carbide-metal
matrix composite structure, which has a matrix material of at least
one of nickel, nickel-chromium, and iron chrome. A plurality of
Fe--Cr-carbide particles are dispersed in the matrix material to
form the composite structure.
[0008] A third aspect of the invention includes a composite
material. The composite material includes a nickel-based component
and a ferrochrome component dispersed within the nickel-based
component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a scanning electron microscope (SEM) micrograph
illustrating representative morphology of a composite powder
consistent with an exemplary embodiment of the invention.
[0010] FIG. 2 is an SEM micrograph illustrating representative
morphology of an as-sintered composite powder consistent with an
exemplary embodiment of the invention.
[0011] FIG. 3 is an SEM micrograph illustrating representative
microstructure of a coating made from a composite powder consistent
with an exemplary embodiment of the invention.
[0012] FIG. 4 is an SEM micrograph illustrating representative
coating morphology of high carbon ferrochrome composite powder
particles clad with nickel consistent with an exemplary embodiment
of the invention.
[0013] FIG. 5 is an SEM micrograph illustrating morphology of a
composite powder formed using an atomization method according to an
exemplary embodiment of the invention.
DETAILED DESCRIPTION
[0014] A method of making a composite carbide powder is provided.
The method may include selecting a ferrochrome material and mixing
the ferrochrome material with a nickel-based material. The
ferrochrome material can be selected from among many materials that
include at least some iron, chrome, and/or carbon. For example, in
one embodiment, the ferrochrome material may include at least one
of (CrFe).sub.7C.sub.3, (CrFe).sub.23C.sub.6, and
(CrFe).sub.3C.sub.2. Further, the ferrochrome material may be
selected in powder form, ingot form, or any other form suitable for
obtaining the ferrochrome precursor material. Similarly, the nickel
based material may be provided in powder form, ingot form, or any
other suitable form.
[0015] The ferrochrome material and the nickel-based material may
be mixed in a variety of ways. For example, the ferrochrome
material and the nickel-based material, especially when in powder
form, may be mixed together with a solvent to form a slurry.
Alternatively, the ferrochrome material and the nickel-based
material may be melted together to form a melt. The disclosed
composite chrome powders, ultimately, may be generated from the
mixture of the ferrochrome material and the nickel-based material.
Various methods for generating the composite chrome powders may be
used including, for example, spray drying and sintering,
atomization, sintering and crushing, mechanical blending, chemical
vapor deposition cladding, electrochemical cladding, mechanical
cladding, and mechanical blending.
[0016] Various additional materials may be added to the mixture of
the ferrochrome material and the nickel-based material. For
example, activated carbon and/or graphite powder may be added to
the mixture. Similarly, in some embodiments, one or more of
silicon, titanium, niobium, vanadium, tantalum, molybdenum,
tungsten, and manganese may be added. For certain applications, any
one of these materials may be limited to no more than 5% by weight
of the chrome composite powder, and a combination of these
materials may be limited to 10% by weight of the chrome composite
powder.
[0017] The disclosed composite chrome powders may have a variety of
particle sizes. In one embodiment, an average particle size of the
composite chrome powder may be from about 3 .mu.m to about 500
.mu.m. In still other embodiments, the average particle size may be
from about 10 .mu.m to about 60 .mu.m.
[0018] The weight percentages of the constituents of the
ferrochrome material may vary according to the requirements of a
particular application. For example, the selected ferrochrome
material may include carbon up to about 14 percent by weight.
Further, the ferrochrome material may contain iron up to about 65
percent by weight. In certain embodiments, however, the amount of
iron may be limited to less than about 35 percent by weight. The
amount of chrome in the ferrochrome material may also vary between
about 15 percent by weight and about 75 percent by weight. Further,
the ferrochrome material may have a iron to chrome weight ratio of
from about 0.2 to 0.5 by weight and a carbon to chrome ratio of
from about 0 to 0.2 by weight.
[0019] Similarly, the weight percentages of the constituents of the
composite chrome powder may also be varied according to the
requirements of a particular application. For example, the
composite chrome powder may include carbon up to about 14 percent
by weight. Further, the composite chrome powder may contain iron up
to about 65 percent by weight. In certain embodiments, however, the
amount of iron may be limited to less than about 35 percent by
weight. The amount of chrome in the composite chrome powder may
also vary between about 15 percent by weight and about 75 percent
by weight. The composite chrome powder may also include up to about
35 percent by weight of nickel.
[0020] A discussion of several exemplary methods for making the
disclosed composite chrome powder follows. As noted above, a high
carbon ferrochrome-nickel chrome composite powder may be made with
a spraying and drying process. Spray drying is a process that
transforms a slurry liquid into a powder by spraying the slurry
into a heated environment. When the slurry enters the heated
environment, the liquid portion of the slurry is vaporized, which
leaves behind the solid particles of the powder. Spray drying can
be used to produce dense particles with a controlled size
distribution.
[0021] In the spray drying process, the ferrochrome powder may be
mixed with a nickel-based powder to form a powder mixture, the
powder mixture may be dispersed in a solvent to form a slurry. A
composite chrome powder may then be generated from the slurry. The
high carbon ferrochrome powder can be obtained from many industrial
and steel making powder vendors, including, for example, FW Winter,
Chemalloy, among others. The high carbon ferrochrome powder may be,
for example, at least one of (CrFe).sub.7C.sub.3, (CrFe)23C6, or
(CrFe).sub.3C.sub.2.
[0022] While the ferrochrome powder and the nickel-based powder may
be selected as individual components, it is also possible to obtain
the high-carbon ferrochrome powder and nickel-based powder in a
pre-mixed form. The powders may be combined, for example, during a
milling process, which reduces average individual particle size
down to the micrometer range to promote uniform mixing and a fine
composite structure in the final product. Milling of the powders
can be accomplished, for example, by use of an Attritor mill
operating at about 400 revolutions-per-minute (rpm). A tungsten
carbide (WC) milling media may be included in the mill in a milling
media-to-powder ratio of about 6:1 to about 8:1 (ratio of weight of
WC to powder added). A solvent (e.g., acetone or heptane) can also
be added for the step of milling the powder mixture to improve
powder distribution during milling. The as-milled powder mixture
may include a particle size distribution of about 0.1 .mu.m to
about 50 .mu.m.
[0023] The powder mixture may be dried in air under a fume hood or
other ventilation system, though the mixture need not be dried in
every case. A sieving machine may be used to separate the WC
milling media from the powder mixture after milling is
complete.
[0024] To prepare the as-milled powder mixture for spray drying,
the powder mixture may be combined with deionized water or an
organic solvent (e.g., acetone, heptane, etc.) to form a slurry
with a certain solid content.
[0025] Additional chemicals can be added to the slurry, including a
binder (e.g., polyvinyl alcohol, gum Arabic, wax, etc.), a
dispensing agent (e.g. sodium metaphosphate), a plasticizer (e.g.
glycerine), and a surfactant (e.g. a synthesized detergent) or
other anti-foaming agent. The slurry is then spray dried at an
elevated inlet temperature (e.g. about 260.degree. C.) to obtain a
powder with an average particle size of about 20 .mu.m to about 80
.mu.m. FIG. 1, for example, is an SEM micrograph illustrating
representative morphology of a composite powder consistent with an
exemplary embodiment of the invention. A distribution of spheroid
particles 10 and 12 with particle sizes of about 20 .mu.m to about
80 .mu.m, respectively, are visible in FIG. 1.
[0026] Optionally, making the composite carbide powder using a
spray drying method may include sintering the as-spray dried powder
at an elevated temperature (e.g. about 1100.degree. C. to about
1280.degree. C.) to form a loosely bonded powder body. After
sintering, this powder body can be broken and sieved to form the
composite carbide powder. Spray drying can produce a powder, as
shown in FIG. 1, for example, that is relatively porous. Sintering
may serve to densify the powder by, for example, forming
metallurgical bonds between individual particles inside each powder
particle, or agglomerate. Sintering may be carried out in a batch
furnace or push furnace in a reducing atmosphere. FIG. 2, for
example, is an SEM micrograph illustrating representative
morphology of as-sintered composite powder particles consistent
with an exemplary embodiment of the invention. As-sintered
particles 16 and 18 have a rough spheroid surface, indicative of
binder material driven out during the sintering process. The
sintered powder shown in FIG. 2 was sintered at 1140.degree. C. for
45 minutes.
[0027] In an embodiment of the invention, approximately 1% to
approximately 2% activated carbon, graphite, or other
carbon-containing powder (e.g. a carbonaceous material) may
optionally be added to the powder mixture during the milling
process. The presence of this activated carbon may promote
conversion of a (CrFe).sub.7C.sub.3 phase to a higher hardness
(CrFe).sub.3C.sub.2 phase during sintering. Specifically, the
approximately 1% to approximately 2% activated carbon, graphite, or
other carbon-containing powder may combine with chrome or other
metals during sintering to form a carbide structure in the final
composite carbide powder.
[0028] The disclosed composite chrome powder may have a composite
structure. Particularly, in one embodiment, at least some of the
particles of the composite chrome powder may include Fe--Cr-carbide
particles dispersed within at least one of a nickel,
nickel-chromium, or iron chrome matrix. To make the composite
structure powder, a metal powder may be mixed with a ferrochrome
powder prior to or during the milling process. The composite
structure may be formed when the combination of the metal and
ferrochrome powders is spray dried. For example, if a metal powder
(e.g. nickel (Ni) or chromium (Cr)) is mixed with the high carbon
ferrochrome powder before milling the high carbon ferrochrome
powder, a composite structure may be produced. This composite
structure may include hard Fe--Cr-carbide particles dispersed
relatively uniformly in a softer, tougher Ni matrix.
[0029] Other composite structures may be generated, however. For
example, the chrome composite powder may include particles having a
ferrochrome core material. A nickel layer and/or a nickel-chromium
layer may be clad on the ferrochrome core material to provide a
composite structure.
[0030] In another embodiment for generating a composite chrome
powder, a chrome composite powder may be made using a cladding
process. Cladding is a process where a material is applied to the
surface of another material and at least partially bound to it.
Cladding of composite powder particles may be used to coat
ferrochrome carbide particles with Ni, Ni--Cr, or Fe--Cr, for
example. The cladding technique may be accomplished by
decomposition of a precursor, such as nickel-carbonyl, followed by
deposition of the Ni, Ni--Cr, or Fe--Cr onto the composite powder
particles. This may produce a softer outer layer of Ni, Ni--Cr, or
Fe--Cr on a harder carbide particle. FIG. 4 shows a SEM micrograph
illustrating representative morphology of high carbon ferrochrome
powder particles clad with nickel consistent with an exemplary
embodiment of the invention. The clad particles are irregular
rather than spheroid in shape.
[0031] In even a further embodiment, a ferrochrome-nickel chrome
composite powder was made with a gas atomization process. FIG. 5
shows the exemplary morphology of a composite powder made using gas
atomization.
[0032] The disclosed composite chrome powders may be used to form
various composite materials for use in many applications. For
example, these composite materials may be used to form stand-alone
parts, composite coatings, etc. The composite materials, like the
composite powders from which they may be derived, may include a
high carbon ferrochrome material combined with a nickel-based
material. In the composite materials, the nickel-based material may
be distributed between the carbon ferrochrome particles. This may
produce a composite material having a composite structure where the
ferrochrome material is dispersed in a nickel matrix.
[0033] Coatings and/or free standing parts using the disclosed
chrome composite powders can be made in a variety of ways. Further,
coatings made from the disclosed chrome composite powders may be
applied to a variety of objects/substrates (e.g. a carbon steel).
For example, powders may be used to form coatings on substrates
with any of a variety of application methods including thermal
spray processes (e.g., plasma spray, flame spray, HVOF, HVAF,
detonation gun spray, and cold spray), laser cladding, plasma
welding (e.g., PTA), and sintering (e.g., as associated with one or
more powder metallurgy processes). FIG. 3 shows an SEM micrograph
illustrating representative microstructure of a coating made from a
composite powder consistent with an exemplary embodiment of the
invention. FIG. 3 is a plan view of a cross section of a coating,
showing high carbon ferrochrome powder particles 20 dispersed in
nickel matrix 22 over a carbon steel substrate (not shown).
EXAMPLE 1
[0034] In one exemplary embodiment of the invention, a powder
mixture was formed by placing 80% high carbon ferrochrome powder
(.about.325 mesh, corresponding to about 45 .mu.m and smaller
individual particle diameter) and 20% carbonyl nickel powder (also
.about.325 mesh) into an Attritor mill and wet milling the mixture
for approximately six hours at 400 revolutions-per-minute (rpm). A
tungsten carbide (WC) milling media was included at a milling
media-to-powder mixture ratio of about 6:1 to about 8:1 (ratio of
weight of WC to powder added). The powder mixture was milled to an
average particle size of about 2 .mu.m. A clear acetone solvent was
added for the step of milling the powder mixture.
[0035] After milling, a sieving machine was used to separate the WC
milling media from the powder mixture. Then the clear acetone
solvent was poured out, and the milled powder mixture was dried by
low temperature baking under a fume hood.
[0036] A 70% solid content slurry was then prepared for spray
drying by combining the powder mixture with deionized water, 1%
polyvinyl alcohol, sodium metaphosphate, glycerine, and a
synthesized detergent. The slurry was then spray dried at about
260.degree. C. to obtain a powder with an average particle size in
the range of about 25 .mu.m to about 70 .mu.m.
[0037] The as-spray dried powder was then sintered in a batch
furnace in a reducing atmosphere at about 1100.degree. C. to about
1280.degree. C. to form a loosely bonded powder body. After
sintering, the loosely bonded powder body was broken and sieved to
form the final composite carbide powder.
EXAMPLE 2
[0038] In a second exemplary embodiment of the invention, a powder
mixture was formed by placing 80% high carbon ferrochrome powder
(.about.325 mesh, corresponding to about 45 .mu.m and smaller
individual particle diameter) and 20% carbonyl nickel powder (also
.about.325 mesh) into an Attritor mill and wet milling the mixture
for approximately six hours at 400 revolutions-per-minute (rpm). A
tungsten carbide (WC) milling media was included at a milling
media-to-powder mixture ratio of about 6:1 to about 8:1 (ratio of
weight of WC to powder added). The powder mixture was milled to an
average particle size of about 2 .mu.m. A clear heptane solvent was
added for the step of milling the powder mixture.
[0039] After milling, a sieving machine was used to separate the WC
milling media from the powder mixture. Then the clear solvent was
poured out, and the milled powder mixture was not dried prior to
preparation for spray drying.
[0040] A 70% solid content slurry was then prepared for spray
drying by combining the powder mixture with deionized water, 1%
polyvinyl alcohol, sodium metaphosphate, glycerine, and a
synthesized detergent. The slurry was then spray dried at about
260.degree. C. to obtain a powder with an average particle size of
about 25 82 m to about 70 .mu.m.
[0041] The as-spray dried powder was then sintered in a batch
furnace in a reducing atmosphere at about 1100.degree. C. to about
1280.degree. C., after which the loosely bonded powder body was
crushed and sieved to form the final composite carbide powder.
EXAMPLE 3
[0042] In a third exemplary embodiment of the invention, high
carbon ferrochrome particles were clad with Ni. To clad the
particles, a predetermined amount of high carbon ferrochrome powder
(.about.325 mesh, corresponding to about 45 .mu.m and smaller
individual particle diameter) was injected into a reaction chamber
and fluidized. Carbonyl nickel, which is an organic precursor, was
added to the reaction chamber after the fluidized bed was heated.
The carbonyl nickel decomposed and a thin Ni film was deposited on
the individual powder particles. Operating conditions were adjusted
so that a predetermined percentage of Ni was deposited on the
composite powder particles.
EXAMPLE 2
[0043] In a fourth exemplary embodiment of the invention, high
carbon ferrochrome nickel powder was made by a gas atomization
method. A high carbon ferrochrome ingot was melted along with
nickel. The raw material proportion was controlled such that the
final powder contained about 20% by weight of nickel, with the
balance of high carbon ferrochrome. The melt was fed through a
nozzle and atomized with and inert gas (e.g., nitrogen or argon).
FIG. 5 is a SEM picture of the composite powder generated.
[0044] Industrial Applicability
[0045] The disclosed high carbon ferrochrome precursor materials
may be used to produce composite powders for applications including
coating of engine parts, cylinders, rods, bearings, joints, cam
shafts, axles, etc. These ferrochrome materials may be selected
from among those materials commonly used for making stainless steel
and tool steel. Thus, these materials may be low cost materials.
Use of this low cost precursor may translate into significant cost
reduction over existing methods. In fact, based on the cost of the
precursor materials, powders produced using carbon ferrochrome
precursors may cost less than half as much as powders and coatings
produced using known materials and methods. Despite the lower cost,
coatings made using the disclosed composite powders may offer
similar or better wear and corrosion resistant properties as the
existing materials. These composite powders may be used in any
industry where wear and corrosion resistant properties are
desired.
[0046] Various composite materials were generated using the
disclosed composite powders. For example, coatings were made using
various systems including a Sulzer MetcoDiamond Jet HVOF system, a
Praxiair JP 5000 HVOF system, a Demoton DSP detonation spray
system, and Dolore Stellite 300M PTA system on steel substrate.
These coatings included Knoop hardness values of between about
950.about.1200 HK at 100.about.300 gram load. These coating went
through wear and friction evaluation and exhibit superior wear
resistance.
[0047] It will be apparent to those skilled in the art that various
modifications and variations can be made in the described powders,
coatings, and methods of making powders and coatings, without
departing from the scope of the invention. Other embodiments of the
invention will be apparent to those skilled in the art from
consideration of the specification and practice of the invention
disclosed herein. It is intended that the specification and
examples be considered as exemplary only, with a true scope of the
invention being indicated by the following claims and their
equivalents.
* * * * *