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Patent 2171191 Summary

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(12) Patent: (11) CA 2171191
(54) English Title: IMPROVED COMPOSITE POWDERS FOR THERMAL SPRAY COATINGS
(54) French Title: POUDRES COMPOSITES AMELIOREES POUR REVETEMENT PAR VAPORISATION THERMIQUE
Status: Term Expired - Post Grant Beyond Limit
Bibliographic Data
(51) International Patent Classification (IPC):
  • C9D 5/46 (2006.01)
(72) Inventors :
  • RANGASWAMY, SUBRAMANIAM (United States of America)
  • MILLER, ROBERT A. (United States of America)
(73) Owners :
  • SULZER PLASMA TECHNIK, INC.
(71) Applicants :
  • SULZER PLASMA TECHNIK, INC. (United States of America)
(74) Agent: SMART & BIGGAR LP
(74) Associate agent:
(45) Issued: 2005-11-15
(86) PCT Filing Date: 1994-09-14
(87) Open to Public Inspection: 1995-03-23
Examination requested: 2001-08-02
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US1994/010418
(87) International Publication Number: US1994010418
(85) National Entry: 1996-03-06

(30) Application Priority Data:
Application No. Country/Territory Date
08/121,824 (United States of America) 1993-09-15

Abstracts

English Abstract


Composite thermal spray powders having a core (28) to
which fine particles of exothennically reacting aluminum or
aluminum alloy (22) and iron or copper fine particles (24)
are bonded. The thermal spray powders may be produced
by an agglomerating technique, and are useful in producing
coatings having both high adhesive bond strength and good
machinability.


French Abstract

Poudres composites améliorées pour revêtements de métallisation à chaud, pourvues d'un noyau (28) auquel sont liées de fines particules d'alliage d'aluminium ou d'aluminium (22) et de fer ou de cuivre (24) qui subissent une réaction exothermique. Les poudres pour métallisation à chaud peuvent être produites par une technique d'agglomération. Elles sont utiles pour produire des revêtements possédant à la fois une grande solidité de liaison et une bonne aptitude à l'usinage.

Claims

Note: Claims are shown in the official language in which they were submitted.


1. A thermal spray powder comprising a plurality of composite
particles, the composite particles of said powder comprising:
a core portion of at least one metal selected from the
group consisting of nickel, iron, cobalt, copper and chromium, and
combinations and alloys thereof, said one metal comprising at least
about 85 percent by weight of said core, and said core comprising
between about 70 to 96 percent by weight of said composite particle;
at the surface of said core portion, a first plurality of
particles of a first metal selected from the group of aluminum and its
alloys, wherein aluminum comprises at least about 80 percent by weight
of said first plurality of particles and wherein said first plurality of
particles comprises between about 3 to 20 percent by weight of said
composite particle;
at the surface of said core portion a second plurality of
particles of a second metal selected from the group consisting of iron,
copper, iron alloys, and copper alloys, wherein at least 80 percent by
weight of said second plurality of particles comprises iron, copper or a
combination of iron and copper, said second plurality of particles
comprising between about 0.5 to 10 percent by weight of said composite
11

particle, and wherein said first and second plurality of particles are
capable of reacting exothermically during a thermal spray process.
2. The thermal spray powder recited is claim 1, wherein said
first plurality of particles are aluminum and said second plurality of
particles are iron.
3. The thermal spray powder recited is claim 1, wherein said
second metal is present as a metal oxide.
4. The thermal spray powder recited in claim 1, wherein said
second metal is present as a metal hydroxide.
5. The thermal spray powder recited in claim 1, wherein said
second metal is present as a metal carbonate.
6. The thermal spray powder recited is claim 1, wherein said
second metal is present as a metal nitrate.
7. The thermal spray powder recited in claim 1, wherein said
core metal comprises an alloying metal selected from the group
consisting of A1, Y, Hf and the Lanthanides.
-12-

8. The thermal spray powder recited in claim 1, wherein said
first and second plurality of particles are fine particulate material
bonded to said core.
9. The thermal spray powder recited in claim 8, further
including a binder by which said fine particulate material is bonded to
said core.
10. The thermal spray powder recited in claim 9, wherein said
binder is polyvinylpyrrolidone.
11. The thermal spray powder recited in claim 8, wherein said
fine particulate material has a size of about 0.2 to 10 microns.
12. A thermal spray powder comprising a plurality of composite
particles, in which the individual composite particles comprise:
a core, at least about 85 percent by weight of which is
formed of a metal selected from the group consisting of nickel, iron,
cobalt, copper, and chromium, and combinations and alloys thereof;
13

a plurality of particles of a first particulate material
bonded to said core, said first particulate material being selected from
the group consisting of aluminum and aluminum alloys with aluminum
forming at least 80 percent by weight of said first particulate material;
a plurality of particles of a second particulate material
bonded to said core, said second particulate material being selected
from the group consisting of iron, copper, and alloys thereof, with iron
copper or a combination of iron and copper forming at least about 80
percent by weight of said second particulate material, said core forming
from about 70 to about 96 percent by weight of said composite particle;
said first particulate material forming from about 3 to
about 20 percent by weight of said composite particle; and
said second particulate material forming from about 0.5 to
about 10 percent by weight of said composite particle.
14

Description

Note: Descriptions are shown in the official language in which they were submitted.


a ,.~ 4 e. t.., f 1"y
I i
t iv : _ 1
WO 95/07767 1 g 1 PCT/US94I10418
IMPROVED COMPOSITB POWDBBS FOR THERMAL SPBAY COdTII~G~S
Z~CH1~ICAL FIBLD
The present invention relates generally to thermal
spray powders and more specifically to low-cost composite
thermal spray powders which are used to form coatings having
high adhesive bond strength and good machineability.
~ACKGRODHD OF THE IrVSRTIOZ(
In order to improve the surface properties of metal
r
parts the parts may be coated utilizing thermal spray
processes. Thermal spraying involves the use of a thermal spray
gun through which a powdered material, typically metal, is
propelled at high velocities. As it passes through the spray
gun, the powder is heated by combustion gases (flame spraying)
or an electric discharge (plasma spraying). The accelerated,
high-temperature particles impact the metal target to form a
coating which adheres to the target surface. In this manner,
the surface properties of a metal part can be significantly
altered to suit a particular application.
Through the years, a number of thermal spray powders
have been developed. One such class of powders is characterized
by composite particles of two or more metals or metal alloys
bonded together with or without a binder material. It is also
la~own that these composite powders may consist of a core metal
with fine particles of another metal being bonded to the core
surface.
SUBSTITUTE SHEET (RULE 26)

2171 191
WO 95/07767 ~ ~ ~ '~ ~. ~~ PCT/LTS94/10418
-2-
For example, in U.S. Patent No. 4,181,525, a thermal
spray powder is described which has particles having a core of
nickel, iron, copper, cobalt or alloys thereof coated with a
binder. The binder contains discrete particles of aluminum and
substantially pure nickel. The core material constitutes from
70-98% of the total mean content of the powder. The core
particles range in size between -60 mesh and +3 microns. In
addition to aluminum, it is disclosed therein that the binder
may further include molybdenum. It has been discovered that
although the fine nickel and aluminum help make the coating
adherent, machineability is limited by the formation of hard
nickel aluminide phases in the coating.
In U.S. Patent No. 4,578,115, entitled, "Aluminum
and Cobalt Coated Thermal Spray Powder," a thermal spray
composite is disclosed having a base constituent formed of
nickel, iron or cobalt and at least one of the modifying
elements, chromium and aluminum, plus, as individual
constituents, aluminum, cobalt and, optionally, molybdenum.
Each particle comprises an alloy core of the base material and
the modifying element, the core having fine particles of the
individual elements secured to the core with a binder.
In addition, the manufacture of binderless clad
particles by mechanical agglomeration is also known. For
example in U.S. Patent No. 4,915,987, to Nara, et al., a
mechanical agglomeration technique is utilized to prepare
particles consisting of a core of one material having a cladding
of another material. In U.S. Patent No. 4,818,567 to Kemp,
metallic coated particles are disclosed which are formed by
preparing a metal flake which is then mechanically applied to
the surface of a core particle.
Powders have also been disclosed in which the
components react exothermically during spraying. U.S. Patent
SUBSTITUTE SHEET (RULE 26~

CA 02171191 2004-09-27
-3-
No. 3,436,248 entitled "Flame Spraying Exothermically Reacting Intermetallic
Compound
Forming Composites" describes methods of coating surfaces by flame spraying
two or more
components which react with one another during flame spraying to form an
intermetallic
compound. It is stated therein that each particle of the flame spray pov~~der
may consist of an
aggregate containing the two components which exothermically react, but that
preferably the
individual particles are in the form of a clad composite consisting of a core
of one of the
components and at least one coating layer of the other component. It is also
disclosed therein that
the composite may consist of separate concentric coating layers of the two
components and a
nucleus of a third material. The methods disclosed for fabricating these prior
art powders include
chemical plating, vapor deposition, and by dispersing one component in a
liquid binder which is
then used to coat the core particle. It is stated that the component which is
mixed with the binder
is finely divided, as for example -325 mesh. It is also disclosed therein that
the aggregates may be
formed by compacting or briquetting the various components into the individual
particles or into
larger aggregates and then breaking these aggregates into the granules. The
overall particle size is
disclosed as between -60 mesh and +3 microns.
Despite the teachings of the prior art, it is clear that a need exists in the
industry
for a low-cost composite thermal spray powder which is highly adherent and yet
which provides
excellent machineability. The present invention provides a composite powder
which meets these
needs.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a thermal spray
powder comprising a plurality of composite particles, in which the individual
composite particles
comprise: a core, at least about 85 percent by weight of which is formed of a
metal selected from
the group consisting of nickel, iron, cobalt, copper, and chromium, and
combinations and alloys
thereof; a plurality of particles of a first particulate material bonded to
the core, the first
particulate material being selected from the group consisting of aluminum and
aluminum alloys
with aluminum forming at least 80 percent by weight of the first particulate
material; a plurality of
particles of a second particulate material bonded to the core, the second
particulate material being
selected from the group consisting of iron, copper, and alloys thereof; with
iron copper or a
combination of iron and copper forming at least about 80 percent by weight of
the second
particulate material, the core forming from about 70 to about 96 percent by
weight of the
composite particle; the first particulate material forming from about 3 to
about 20 percent by
weight of the composite particle; and the second particulate material forming
from about 0.5 to
about 10 percent by weight of the composite particle.

CA 02171191 2004-09-27
-4-
The present invention may provide a thermal spray powder which is specifically
designed to form a coating that bonds strongly to metal substrates (in many
cases without the need
for extensive surface preparation) and which is both wear-resistant and
readily machinable. The
individual particles which make up the powder may be composite structures
formed by
agglomeration techniques. The particles have a core region and a surface
region. The core may be
selected from one or more of the following metals: Ni, Fe, Co, Cu, and Cr. The
core may also
contain up to about 15% by weight of additional alloying metals such as Al, Y,
Hf and the
Lanthanides. The surface region may be made up of finely divided particles
that are either bonded
to the core by a binder or may be partially embedded in the core surface. At
least two separate
types of fme particles are bonded to the core to form the composite particle
surface. The first type
(first particulate material) is aluminum or an aluminum alloy. A number of
other metals, such as
silicon, magnesium, and titanium may be combined with the aluminum where an
aluminum alloy
is used, but aluminum should constitute at least 80% by weight of the first
particulate material. In
general, pure aluminum is preferred to any alloy. Preferred aluminum alloys
are aluminum/silicon
and aluminum/copper. The second type of fine particle (second particulate
material) is selected
from the group consisting of Fe and Cu, alloys of these metals with other
metals (where Fe and/or
Cu make up at least 80% by weight of the second particulate material) for
example, Fe/Ni and
Cu/Ni and oxides, hydroxides, carbonates, and/or nitrates of Fe and/or Cu.
In another aspect, the present invention may provide a method of making the
novel powders of the present invention. The method includes combining the
components to form
the desired aggregates. In a most preferred embodiment, this method includes
the mechanical
agglomeration of the first and second fine particulate materials onto t:he
surface of the core
particles through the use of limited-duration attrition milling as described
in U.S. patent No.
5,372,845 issued December 13, 1994 and entitled "Method for Preparing Binder-
Free Clad
Powder".

CA 02171191 2004-09-27
-5-
In still another aspect the present invention may provide a method of forming
a
coating by thermal spraying the novel composite powders of the present
invention on a target.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an elevational view of a composite particle made in accordance
with
the present invention.
Figure 2 is a cross-sectional view of a composite particle made in accordance
with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As set forth in the foregoing summary, the present invention relates to an
improved composite flame spray powder which produces a highly-adherent metal
coating that
exhibits superior machinability characteristics. In the broadest sense, the
thermal spray powders
of the invention comprise a core material to which much smaller particles,
referred to herein as
fine particulate material, are bonded. The selection of materials, their
relative amounts, and their
distribution all combine to form a particle and thus a powder which can be
sprayed using
conventional thermal spray devices and parameters such that an exothermic
reaction is initiated in
flight. This exothermic reaction produces additional particle heat and results
in a combination of
metals which produces the novel coating of the present invention.
PARTICLE CORE
The core or base material of the particles is most preferably selected from
the
group consisting of nickel, iron, cobalt, copper and chromium. Alloys of these
materials may also
be suitable. For example, the core material may comprise an

'- ~ 21 l 1 191 PCT/US94110418
WO 95/07767 . ' ..°.
-6-
alloy of nickel and copper or nickel, chromium and iron. Minor
amounts of other metals which do not alter the basic
a
metallurgical properties of the final coating may be tolerated
in most instances in the core.
L
The core material comprises from about 70 to about
96 percent by weight of the individual particle, more preferably
from about 80 to about 95 percent by weight, and most preferably
from about 83 to about 93 percent by weight of the particle.
Thus, the core material most preferably comprises from about 83
to about 93 percent of the novel thermal spray powder of the
present invention.
The core material is initially provided as a coarse
particle to which the additional components are preferably
bound. The core particles range in size from about 38 to about
125 microns in diameter, more preferably from about 45 to about
106 microns and most preferably from about 45 to about 90
microns in diameter. In terms of the final powder the average
core size is most preferably from about 60 to about 90 percent.
In terms of mesh size the core particles which are used to
produce the composite particles of the present invention are
about -80/+635 and preferably -140/+400 U.S. standard mesh
size. No significant change in the size of the core particles
occurs during agglomeration with the fine particulate materials
and thus these core size data also accurately describe the core
in the final powder.
FIFE PARTICULATE MATERIAL
As stated, the novel composite particles of the
present invention further include a plurality of discrete
regions of two dissimilar materials which interact to produce an
exothermic reaction during thermal spraying. While it may be
possible to provide these materials as internal inclusions or
SUBSTITUTE SHEET (RULE 26)

CA 02171191 2004-09-27
regions within the particle slightly below the core surface, in the most
preferred embodiment of
the present invention the fme particulate materials comprise substantially
distinct particles bonded
to the core surface. This may be achieved by a number of techniques such as
spray drying and the
like. In one embodiment, the fine particulate materials are added to a liquid
binder which is then
used to coat the core particles. Numerous suitable binders will be known to
those of skill in the art
such as phenolic binders. PVP (polyvinylpyrrolidone) is a particularly
preferred binder. Where a
binder is used in the present invention, the binder should constitute no more
than about 5 percent
by weight of the particle, more preferably less than about 3 percent by weight
of the particle, and
most preferably a fugitive binder is utilized.
In a more preferred embodiment, the particles of the present invention are
produced by mechanical agglomeration using the attritor agglomeration
described in U.S. Patent
No. 5,372,845 issued December 13, 1994, and entitled "Method for Preparing
Binder-Free Clad
Powder", assigned to the assignee of the present application. Particles
produced by this method
have the fine particulate materials embedded slightly in the surface of the
core particles; on
average from about 1 to about 10 percent by volume of each fine particle is
embedded in the core.
Of course, there must be sufficient bonding between the fine particulate
materials and the core
particles such that the composite particles remain intact in storage and
during spraying.
At least two separate types of fme particulate materials are bonded to the
core to
form the particle surface. The first particulate material is aluminum or an
aluminum alloy. A
number of other metals, such as silicon, magnesium, and titanium may be
combined with the
..1".....:........., ...l..e..,. ...., .,1.....,.:..,........ ..11......,.
..,....7 t_..a ..1_..r~._.._~ ._t____t~ __~_~_u__u_ _~ i___~ nn

WO 95/07767 . ~ _ ~' 2 ~ 71191 pCT~S94/10418
_g_
percent by weight of the first particulate material. In
general, pure aluminum is preferred to any alloys. Preferred
aluminum alloys are aluminum/silicon and aluminum/copper. The
second type of fine particulate material is selected from the
group consisting of Fe, Cu, alloys of these metals with other
metals, for example, Fe/Ni and Cu/Ni, (where Fe and/or Cu make
up at least 80 percent by weight of the second particulate
material) and oxides, hydroxides, carbonates, and/or nitrates of
Fe and/or Cu.
Thus, it will be understood that the plurality of
fine particulate dissimilar materials comprise at least two
dissimilar materials provided as discrete particles. Referring
now to Figures 1 and 2 of the drawings, composite core particle
20 is shown on which a plurality of fine particulate materials
22 and 24 (not to scale) are shown partially bonded to or
embedded in surface region 26 of core 28. In this illustration,
fine particles 22 are aluminum and fine particles 24 are iron.
The first and second particles are in intimate contact such that
they undergo an exothermic reaction during thermal spraying.
The aluminum or aluminum alloy fine particulate
material comprises from about 3 to about 20 percent by weight of
the individual composite particle, more preferably from about 4
to about 15 percent by weight, and most preferably from about 5
to about 12 percent by weight of the composite particle. Thus,
the first fine particulate material most preferably comprises
from about 5 to about 12 percent by weight of the finished
thermal spray powders of the present invention.
The second fine particulate material comprises from
about 0.5 to about 10 percent by weight of the individual
composite particle, more preferably from about 1 to about 7, and
most preferably from about 1.5 to about 4 percent by weight.
SUBSTITUTE SHEET (RULE 26)

WO 95/07767 2171191 pCT/L1S94/10418
. _~ a a, ' ',, ~.
-g_
Thus, the second fine particulate material comprises from about
1.5 to about 4 percent by weight of the final powder.
The particles of the fine particulate materials
a
range in size from about 0.2 to about 10 microns in diameter,
more preferably from about 0.5 to about 5 microns aad most
preferably from about 1.0 to about 4 microns in diameter.
The thermal spray material of the present invention
is most preferably provided in the form of a powder although
compaction or the like into wires or rods may be possible in a
particular application. Where provided as a powder, the present
invention is preferably about -80/+635 U.S, mesh, more
preferably about -140/+400 U.S, mesh and most preferably about
-140/+325 U.S. mesh.
In accordance with the method of the present
invention, the novel powders described herein are sprayed using
conventional thermal spray apparatus to form highly-adherent,
machinable coatings on metal substrates. The operating
parameters of the thermal spray apparatus are conventional, but
must provide sufficient heat to the powder to produce the
desired exothermic reaction involving the dissimilar types of
fine particulate materials of the powder. The dissimilar fine
particles thus react with one another and interact with the core
material and possibly the ambient atmosphere to produce
superheated droplets which bond exceptionally well to many
substrates. Some steels and other substrates may be coated
adequately in this manner without the need for prior surface
roughening. By elimination of any significant amount of nickel
in the fine particulates, the resultant coating lacks the nickel
aluminide phases which otherwise reduce the machineability of
the coating. In order to more fully illustrate the present
invention the following examples are provided which are not in
any manner intended to limit the full scope of the invention as
described in the appended claims.
SUBSTITUTE SHEET (RULE 26)

WO 95!07767 ~ ' s v, t ~'y PCTIUS94/10418
-10-
cosy cLennaRG Bal~n$g~s~T
1 60Fe-40fti alloy2% Fe (2~t) 2% P~TPExcellent self
(-140+325 mesh) 5% A1 (2~un)Binder bonding and
machinability
2 90Cu-10A1 alloy 2% Fe (2~m) 2% PVP Excellent self
(-120+325 mesh) 5% A1 (2~.~m)Binder bonding and
machinability
While the invention has been described in connection
with specific embodiments thereof, it is evident that many
alternatives, modifications, and variations will be apparent to
those skilled in the art in light of the foregoing description.
Accordingly, it is intended to embrace all such alternatives,
modifications and variations that fall within the spirit and
broad scope of the appended claims.
StJ$STITUTE SHEET (RULE 26)

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Event History

Description Date
Inactive: IPC expired 2022-01-01
Inactive: IPC expired 2016-01-01
Inactive: Expired (new Act pat) 2014-09-14
Inactive: IPC from MCD 2006-03-12
Inactive: IPC from MCD 2006-03-12
Grant by Issuance 2005-11-15
Inactive: Cover page published 2005-11-14
Pre-grant 2005-08-30
Inactive: Final fee received 2005-08-30
Notice of Allowance is Issued 2005-03-07
Notice of Allowance is Issued 2005-03-07
4 2005-03-07
Letter Sent 2005-03-07
Inactive: Approved for allowance (AFA) 2005-02-22
Amendment Received - Voluntary Amendment 2004-09-27
Inactive: S.30(2) Rules - Examiner requisition 2004-03-25
Inactive: Application prosecuted on TS as of Log entry date 2001-10-12
Letter Sent 2001-10-12
Inactive: Status info is complete as of Log entry date 2001-10-12
Amendment Received - Voluntary Amendment 2001-08-02
Request for Examination Requirements Determined Compliant 2001-08-02
All Requirements for Examination Determined Compliant 2001-08-02
Application Published (Open to Public Inspection) 1995-03-23

Abandonment History

There is no abandonment history.

Maintenance Fee

The last payment was received on 2005-08-25

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Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
SULZER PLASMA TECHNIK, INC.
Past Owners on Record
ROBERT A. MILLER
SUBRAMANIAM RANGASWAMY
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Representative drawing 1997-06-12 1 6
Cover Page 1996-06-11 1 17
Abstract 1995-03-22 1 41
Description 1995-03-22 10 396
Claims 1995-03-22 4 98
Drawings 1995-03-22 1 20
Claims 2001-11-01 4 118
Description 2004-09-26 10 404
Claims 2004-09-26 4 109
Representative drawing 2005-02-27 1 13
Cover Page 2005-10-18 1 41
Reminder - Request for Examination 2001-05-14 1 117
Acknowledgement of Request for Examination 2001-10-11 1 194
Commissioner's Notice - Application Found Allowable 2005-03-06 1 162
PCT 1996-03-05 12 600
Fees 2003-08-24 1 37
Fees 1997-09-01 1 35
Fees 2004-08-22 1 34
Correspondence 2005-08-29 1 32
Fees 2005-08-24 1 35
Fees 1996-08-21 1 46