U.S. patent application number 11/596624 was filed with the patent office on 2008-11-06 for wear resistant alloy powders and coatings.
This patent application is currently assigned to Praxair Surface Technologies, Inc.. Invention is credited to William J. C. Jarosinski, Lewis B. Temples.
Application Number | 20080274010 11/596624 |
Document ID | / |
Family ID | 35462777 |
Filed Date | 2008-11-06 |
United States Patent
Application |
20080274010 |
Kind Code |
A1 |
Jarosinski; William J. C. ;
et al. |
November 6, 2008 |
Wear Resistant Alloy Powders and Coatings
Abstract
This invention relates to alloys and wear resistant alloy
powders useful for deposition through thermal spray devices. The
alloys comprise from about 20 to 65 weight percent chromium, about
20 to 65 weight percent molybdenum, about 0.5 to 3 weight percent
carbon, and about 10 to 45 weight percent nickel. The wear
resistant alloy powders are useful for forming coatings having the
same composition.
Inventors: |
Jarosinski; William J. C.;
(Carmel, IN) ; Temples; Lewis B.; (Plainfield,
IN) |
Correspondence
Address: |
Gerald L. Coon;Praxair, Inc.
39 Old Ridgebury Road, M1-557
Danbury
CT
06810
US
|
Assignee: |
Praxair Surface Technologies,
Inc.
|
Family ID: |
35462777 |
Appl. No.: |
11/596624 |
Filed: |
May 26, 2005 |
PCT Filed: |
May 26, 2005 |
PCT NO: |
PCT/US05/18423 |
371 Date: |
September 10, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60574929 |
May 28, 2004 |
|
|
|
Current U.S.
Class: |
420/588 ;
420/428; 420/429; 420/580 |
Current CPC
Class: |
C22C 19/053 20130101;
C22C 27/04 20130101; B22F 9/082 20130101; B22F 2201/10 20130101;
C22C 1/045 20130101; C22C 27/06 20130101; B22F 2999/00 20130101;
B22F 2999/00 20130101; B22F 1/0003 20130101 |
Class at
Publication: |
420/588 ;
420/428; 420/429; 420/580 |
International
Class: |
C22C 30/00 20060101
C22C030/00; C22C 27/06 20060101 C22C027/06; C22C 27/04 20060101
C22C027/04 |
Claims
1. An alloy comprising from about 20 to 65 weight percent chromium,
about 20 to 65 weight percent molybdenum, about 0.5 to 3 weight
percent carbon, and about 10 to 45 weight percent nickel.
2. The alloy of claim 1 comprising about 10 to 45 weight percent
nickel plus cobalt.
3. The alloy of claim 1 comprising about 0.5 to 3 weight percent
carbon plus boron, silicon and/or manganese.
4. The alloy of claim 1 further comprising precipitated carbides
and optionally nitrides of chromium and molybdenum interspersed
throughout.
5. The alloy of claim 4 in which the volume fraction of the
precipitated carbides and optionally nitrides dispersed throughout
the alloy is 0.25 or greater.
6. The alloy of claim 4 in which the size of the precipitated
carbides and optionally nitrides is between 0.5 or less and 20
micrometers in its largest dimensions.
7. A wear resistant powder useful for deposition through thermal
spray devices, the powder comprising an alloy of about 20 to 65
weight percent chromium, about 20 to 65 weight percent molybdenum,
about 0.5 to 3 weight percent carbon, and about 10 to 45 weight
percent nickel.
8. The wear resistant powder of claim 7 in which the alloy further
comprises about 10 to 45 weight percent nickel plus cobalt.
9. The wear resistant powder of claim 7 in which the alloy further
comprises about 0.5 to 3 weight percent carbon plus boron, silicon
and/or manganese.
10. The wear resistant powder of claim 7 in which the alloy further
comprises precipitated carbides and optionally nitrides of chromium
and molybdenum interspersed throughout.
11. The wear resistant powder of claim 10 in which the volume
fraction of the precipitated carbides and optionally nitrides
dispersed throughout the alloy is 0.25 or greater.
12. The wear resistant powder of claim 10 in which the size of the
precipitated carbides and optionally nitrides is between 0.5 or
less and 20 micrometers in its largest dimensions.
Description
FIELD OF THE INVENTION
[0001] This invention relates to chromium-molybdenum alloys and
wear resistant alloy powders useful for deposition through thermal
spray devices. The wear resistant alloy powders are useful for
forming coatings having the same composition.
BACKGROUND OF THE INVENTION
[0002] Hard surface coating metals and alloys are known in the art.
For example, chromium metal has been used as an electroplated
coating for many years to restore worn or damaged parts to their
original dimensions, to increase wear and corrosion resistance, and
to reduce friction. Hard chromium electroplate, however, has a
number of limitations. When the configuration of the part becomes
complex, obtaining a uniform coating thickness by
electro-deposition is difficult. A non-uniform coating thickness
necessitates grinding to a finished surface configuration, which is
both difficult and expensive with electroplated chromium because of
its inherent brittleness and hardness. The rate of deposition by
electroplating is relatively low, and thus a substantial capital
investment in plating equipment is required. It is often necessary
to apply one or more undercoats, or to use expensive surface
cleaning and etching procedures to prepare substrates. Disposal of
spent plating baths also adds significantly to the cost of the
process.
[0003] An alternative method of depositing chromium metal is by
metal spraying such as with a plasma, high velocity oxygen fuel
(HVOF) or detonation gun. This method allows the coating to be
applied to almost any metallic substrate without using undercoats.
The coating thickness can be controlled very closely so that any
subsequent finishing can be kept to a minimum. However,
considerable finishing may be required for certain coatings with
wear resistance tailored for specific applications.
[0004] U.S. Pat. No. 3,846,084 discloses coatings made by the
plasma or detonation gun process that are superior to hard chromium
electroplate in compatibility, frictional characteristics and wear
resistance by incorporating a dispersion of chromium carbide
particles in a chromium matrix. Coatings of this type can be made
from mechanical mixtures of powders. However, there are certain
limitations to the quality of coatings made from them. Plasma, HVOF
and detonation-gun coatings result in a multilayer structure of
overlapping lamellae or "splats." Each splat is derived from a
single particle of the powder used to produce the coating. There
appears to be little, if any, combining or alloying of two or more
powder particles during the coating deposition process.
[0005] U.S. Pat. No. 6,562,480 B1 discloses a wear resistant
coating for protecting a surface undergoing sliding contact with
another surface such as piston rings and cylinder liners of
internal combustion engines. The wear resistant coating is applied
by HVOF deposition of a powder which comprises a blend of about 13
weight percent to about 43 weight percent of a nickel-chromium
alloy, about 25 weight percent to about 64 weight percent chromium
carbide, and about 15 weight percent to about 50 weight percent
molybdenum.
[0006] U.S. Pat. No. 6,503,290 B1 discloses a corrosion resistant
powder useful for deposition through thermal spray devices. The
powder comprises about 30 to 60 weight percent tungsten, about 27
to 60 weight percent chromium, about 1.5 to 6 weight percent
carbon, a total of about 10 to 40 weight percent cobalt plus nickel
and incidental impurities plus melting point suppressants. The
corrosion resistant powder is useful for forming coatings having
the same composition.
[0007] A need continues to exist for powders and coatings that can
be deposited by thermal spray devices and that exhibit excellent
wear and/or corrosion resistance. Therefore, a need continues to
exist for developing new powders and for exploring their potential
for thermal spray deposition of wear and corrosion resistant
coatings. It would therefore be desirable in the art to provide
powders and coatings that can be deposited by thermal spray devices
and that exhibit excellent wear and corrosion resistance.
SUMMARY OF THE INVENTION
[0008] This invention relates to alloys comprising about 20 to 65
weight percent chromium, about 20 to 65 weight percent molybdenum,
about 0.5 to 3 weight percent carbon, and about 10 to 45 weight
percent nickel. The alloys include precipitated carbides (and
optionally nitrides) of chromium and molybdenum interspersed
throughout. This invention also relates to wear resistant alloy
powders useful for deposition through thermal spray devices. The
powders comprise an alloy of about 20 to 65 weight percent
chromium, about 20 to 65 weight percent molybdenum, about 0.5 to 3
weight percent carbon, and about 10 to 45 weight percent nickel.
The wear resistant alloy powders are useful for forming coatings
having the same composition.
DETAILED DESCRIPTION OF THE INVENTION
[0009] As indicated above, this invention relates to wear resistant
alloy powders useful for deposition through thermal spray devices
such as plasma, HVOF or detonation gun. The powders are made from
alloys comprising about 20 to 65 weight percent chromium, about 20
to 65 weight percent molybdenum, about 0.5 to 3 weight percent
carbon, and about 10 to 45 weight percent nickel. The
alloys-include precipitated carbides and optionally nitrides of
chromium and molybdenum interspersed throughout. The alloys are
useful for forming wear resistant powders and coatings having the
same composition.
[0010] The alloys herein rely upon a large concentration of
chromium and molybdenum for excellent wear resistance.
Advantageously, the alloys contain at least about 20 weight percent
chromium, preferably at least about 30 weight percent chromium, and
more preferably at least about 35 weight percent chromium. Powders
containing less than about 20 weight percent chromium may exhibit
inadequate wear resistance for many applications. Chromium levels
in excess of about 65 weight percent may tend to detract from the
wear resistance of the coating because the coating may become too
brittle.
[0011] Similarly, the alloys contain at least about 20 weight
percent molybdenum, preferably at least about 25 weight percent
molybdenum, and more preferably about 30 or 35 weight percent
molybdenum. Powders containing less than about 20 weight percent
molybdenum may exhibit inadequate wear resistance for many
applications. Molybdenum levels in excess of about 65 weight
percent may tend to detract from the wear resistance of the coating
because the coating may become too brittle.
[0012] In an embodiment of this invention, the alloys comprise
about 20 to 65, preferably about 30 to 60, and more preferably
about 35 to 55, weight percent chromium; about 20 to 65, preferably
about 25 to 60, and more preferably about 30 to 55, weight percent
molybdenum; about 0.5 to 3, preferably about 1 to 2.5, and more
preferably about 1.5 to 2, weight percent carbon; and about 10 to
45, preferably about 15 to 35, and more preferably about 20 to 35,
weight percent nickel. These alloys are useful for forming wear
resistant powders and coatings having the same composition.
[0013] In another embodiment of this invention, the alloys comprise
about 50 to 90, preferably about 60 to 80, and more preferably
about 65 to 75, weight percent chromium and molybdenum; about 0.5
to 3, preferably about 1 to 2.5, and more preferably about 1.5 to
2, weight percent carbon; and about 10 to 45, preferably about 15
to 35, and more preferably about 20 to 35, weight percent nickel.
These alloys are useful for forming wear resistant powders and
coatings having the same composition.
[0014] The carbon concentration controls the hardness and wear
properties of coatings formed with the powders. A minimum of about
0.5 weight percent carbon may be necessary to impart adequate
hardness into the coatings. If the carbon exceeds about 3 weight
percent, the melting temperature of the powder may become too high
and it may become too difficult to atomize the powder.
[0015] In another embodiment of this invention, cobalt may be
included in the alloys, powders and coatings. The powders may
contain about 10 to 45, preferably about 15 to 35, and more
preferably about 20 to 35, weight percent nickel plus cobalt. This
may facilitate the melting of the chromium/molybdenum/carbon
combination that, if left alone, would form carbides having too
high of melting temperatures for atomization. Increasing the
concentration of cobalt and nickel may also tend to increase the
deposition efficiency for thermal spraying the powder. Because
total nickel plus cobalt levels above about 45 weight percent may
tend to soften the coating and limit the wear resistance of the
coating, the total concentration of nickel plus cobalt may best be
maintained below about 45 weight percent. In addition, the alloys
may contain only nickel or cobalt since coatings with only nickel
(e.g., about 10 to 45 weight percent nickel) or only cobalt (e.g.,
about 10 to 45 weight percent cobalt) may form powders with wear
resistance tailored for specific applications. But for most
applications, cobalt and nickel appear to be interchangeable.
[0016] In another embodiment of this invention, boron, silicon
and/or manganese may be included in the alloys, powders and
coatings. The alloys may contain about 0.5 to 3, preferably about 1
to 2.5, and more preferably about 1.5 to 2, weight percent carbon
plus boron, silicon and/or manganese. To facilitate melting for
atomization, the alloys may optionally contain melting point
suppressants such as boron, silicon and manganese. An excessive
amount of melting point suppressants may tend to decrease both
corrosion and wear resistance.
[0017] As indicated above, the alloys include precipitated carbides
(and optionally nitrides) of chromium and molybdenum interspersed
throughout. The alloys may contain a volume fraction of the
precipitated carbides and optionally nitrides in excess of 0.25.
Preferably, the volume fraction of the precipitated carbides and
optionally nitrides dispersed in the alloys may be 0.25 or greater
and more preferably between 0.35 and 0.80. Preferably, the
precipitated carbide and optionally nitride grains may be of
micrometer and submicrometer size, for example, between 0.5 or less
and 20 micrometers, more preferably between 1 and 10 micrometers in
its largest dimensions. The size and volume fraction of the
precipitated carbides and optionally nitrides can be adjusted by
varying the chromium, molybdenum and carbon content.
[0018] The alloys of this invention may be blended with molybdenum
to form powders with wear resistance tailored for specific
applications. The amount of molybdenum that may be blended with the
alloys of this invention is not narrowly critical and may range
from about 10 to 50, preferably about 15 to 45, and more preferably
about 20 to 40, weight percent of the total alloy/molybdenum blend
composition. The amount of blended molybdenum is in addition to the
amount of alloy molybdenum. The amount of blended molybdenum will
depend upon the desired application.
[0019] Advantageously, the powders of this invention may be
produced by means of inert gas atomization of a mixture of elements
in the proportions stated herein. Preferred atomization methods
that may be employed in making the powders of this invention are
described in U.S. Pat. No. 5,863,618, the disclosure of which is
incorporated herein by reference. The alloys of these powders are
typically melted at a temperature of about 1600.degree. C. and then
atomized in a protective atmosphere (e.g., argon, helium or
nitrogen). Most advantageously the atmosphere is argon. A nitrogen
atmosphere may be employed which may result in the formation of
additional hard phases interspersed throughout the alloys, e.g.,
nitrides. As indicated above, to facilitate melting for
atomization, the alloy may optionally contain melting point
suppressants like boron, silicon and manganese.
[0020] Alternatively, sintering and crushing, sintering and spray
drying, sintering and plasma densification are possible methods for
manufacturing the powders. Gas atomization however represents the
most effective method for manufacturing the powder. Gas atomization
techniques typically produce a powder having a size distribution of
about 1 to 500 microns. For thermal spray applications, the powder
is classified to a size of about 1 to 100 microns.
[0021] Coatings may be produced using the alloys of this invention
by a variety of methods well known in the art. These methods
include thermal spray (plasma, HVOF, detonation gun, etc.), laser
cladding; and plasma transferred arc (PTA). Thermal spray is a
preferred method for deposition of powders to form the coatings of
this invention. The wear resistant alloy powders of this invention
are useful for forming coatings having the same composition.
[0022] The alloy powders of this invention are useful for forming
coatings or objects having excellent wear properties, for example,
wear resistant coatings for protecting surfaces undergoing sliding
contact with other surfaces such as piston rings and cylinder
liners of internal combustion engines.
[0023] The examples that follow are intended as an illustration of
certain preferred embodiments of the invention, and no limitation
of the invention is implied.
EXAMPLE 1
[0024] The alloy powders listed in Table I were made by processes
alike to those described in U.S. Pat. No. 5,863,618.
TABLE-US-00001 TABLE I Alloy Cr Mo Ni C Other A 45 20 32 2 1 B B 42
23 33 2 C 40 35 22.5 2.5 D 39 20 40 1 E 35 40 23 2 F 34 22 43 1 G
30 30 39 1 H 50 21 3(+20 Co) 0.5 0.4 B, 2.3 Fe, 2.2 Si I 51 22
13(+10 Co) 1.8 1.8 J 35 35 27.5 1.5 0.5 B
[0025] Other variations and modifications of this invention will be
obvious to those skilled in the art. This invention is not limited
except as set forth in the claims.
* * * * *