U.S. patent application number 14/733144 was filed with the patent office on 2015-10-08 for multilayer overlays and methods for applying multilayer overlays.
The applicant listed for this patent is Extreme Surface Protection Ltd.. Invention is credited to Trevor Aitchison, R. Allan Heflin.
Application Number | 20150283792 14/733144 |
Document ID | / |
Family ID | 43354637 |
Filed Date | 2015-10-08 |
United States Patent
Application |
20150283792 |
Kind Code |
A1 |
Aitchison; Trevor ; et
al. |
October 8, 2015 |
MULTILAYER OVERLAYS AND METHODS FOR APPLYING MULTILAYER
OVERLAYS
Abstract
A wear resistant multilayer overlay includes a first layer on at
least a surface of an article, and a second layer metallurgically
bonded to at least a portion of the first layer. The first layer
includes a first continuous metallic matrix and at least one of
first hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the first continuous metallic matrix, wherein
the first hard particles are at least one of transition metal
carbide particles and boron nitride particles. The second layer
includes a second continuous metallic matrix and at least one of
second hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts, embedded in the second continuous metallic matrix,
wherein the second hard particles are at least one of transition
metal carbide particles and boron nitride particles. Related
methods and articles of manufacture also are disclosed.
Inventors: |
Aitchison; Trevor; (Powys,
GB) ; Heflin; R. Allan; (Lake Forest, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Extreme Surface Protection Ltd. |
Windsor |
|
CA |
|
|
Family ID: |
43354637 |
Appl. No.: |
14/733144 |
Filed: |
June 8, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12488167 |
Jun 19, 2009 |
9050673 |
|
|
14733144 |
|
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Current U.S.
Class: |
428/636 |
Current CPC
Class: |
B22F 7/08 20130101; B23K
35/3053 20130101; B23K 9/167 20130101; C22C 26/00 20130101; Y10T
428/12493 20150115; B23K 2103/04 20180801; B23K 9/042 20130101;
B32B 2264/108 20130101; Y10T 428/12076 20150115; B23K 35/308
20130101; F16L 57/06 20130101; B23K 2101/34 20180801; Y10T
428/12639 20150115; B23K 2103/05 20180801; B23K 9/173 20130101;
B32B 15/01 20130101; B23K 2103/26 20180801; C23C 28/027 20130101;
B23K 35/0261 20130101; Y10T 428/12056 20150115; B23K 2101/18
20180801; B23K 2103/08 20180801; C23C 28/023 20130101; C23C 28/021
20130101; B22F 5/10 20130101; F16L 9/14 20130101; B23K 35/3033
20130101; B32B 15/043 20130101 |
International
Class: |
B32B 15/04 20060101
B32B015/04 |
Claims
1. A wear resistant multilayer overlay comprising: a first layer
comprising a first continuous metallic matrix and at least one of
first hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the first continuous metallic matrix, wherein
the first hard particles are at least one of transition metal
carbide particles and boron nitride particles; and a second layer
metallurgically bonded to at least a portion of the first layer,
the second layer comprising a second continuous metallic matrix and
at least one of second hard particles, blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles and PCD compacts embedded in the second continuous
metallic matrix, wherein the second hard particles are at least one
of transition metal carbide particles and boron nitride
particles.
2. The wear resistant multilayer overlay of claim 1, wherein the
first layer comprises blocky diamond particles embedded in the
first continuous metallic matrix.
3. The wear resistant multilayer overlay of claim 1, wherein the
first metallic matrix and the second metallic matrix are metal
alloys.
4. The wear resistant multilayer overlay of claim 3, wherein the
first metallic matrix and the second metallic matrix each
individually comprise a material selected from a carbon steel, a
stainless steel, and a nickel-chromium superalloy.
5. The wear resistant multilayer overlay of claim 1, wherein the
first hard particles and the second hard particles each
individually comprise carbide particles of at least one of
titanium, vanadium, chromium, manganese, iron, cobalt, nickel,
copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium,
rhodium, palladium, silver, cadmium, hafnium, tantalum, and
tungsten.
6. The wear resistant multilayer overlay of claim 1, wherein the
total concentration of first hard particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the first
continuous metallic matrix is 25 to 85 volume percent based on the
total volume of the first layer.
7. The wear resistant multilayer overlay of claim 1, wherein the
concentration of first hard particles, blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts embedded in the first continuous
metallic matrix is 25 to 75 volume percent based on the total
volume of the first layer.
8. The wear resistant multilayer overlay of claim 1, wherein the
concentration of first hard particles, blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts embedded in the first continuous
metallic matrix is 25 to 60 volume percent based on the total
volume of the first layer.
9. The wear resistant multilayer overlay of claim 6, wherein the
total concentration of second hard particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the first
continuous metallic matrix is at least 30 volume percent based on
the total volume of the first layer.
10. The wear resistant multilayer overlay of claim 1, wherein the
total concentration of second hard particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the second
continuous metallic matrix is 10 to 85 volume percent based on the
total volume of the second layer.
11. The wear resistant multilayer overlay of claim 1, wherein the
total concentration of second hard particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the second
continuous metallic matrix is 10 to 50 volume percent based on the
total volume of the second layer.
12. The wear resistant multilayer overlay of claim 1, wherein the
total concentration of second hard particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the second
continuous metallic matrix is 25 to 50 volume percent based on the
total volume of the second layer.
13. The wear resistant multilayer overlay of claim 2, wherein the
total concentration of blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the first continuous metallic matrix is up to
20 volume percent based on the total volume of the first layer.
14. The wear resistant multilayer overlay of claim 2, wherein the
total concentration of blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the first continuous metallic matrix is in the
range of 0.5 to 20 volume percent based on the total volume of the
first layer.
15. The wear resistant multilayer overlay of claim 1, wherein at
least 50 volume percent of the second hard particles embedded in
the second continuous metallic matrix have a mesh size of -10 to
+400.
16. The wear resistant multilayer overlay of claim 1, wherein at
least 50 volume percent of the second hard particles embedded in
the second continuous metallic matrix have a mesh size of -30 to
+400.
17. The wear resistant multilayer overlay of claim 1, wherein at
least 50 volume percent of the total volume of blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the second
continuous metallic matrix has a size of -10 mesh to +0.01 micron
in linear diameter.
18. The wear resistant multilayer overlay of claim 1, wherein a
thickness of the first layer is in the range of 3 to 15 mm.
19. The wear resistant multilayer overlay of claim 1, wherein a
thickness of the second layer is in the range of 3 to 8 mm.
20. The wear resistant multilayer overlay of claim 1 comprising: a
first layer comprising a first continuous metallic matrix and at
least one of first hard particles, blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts embedded in the first continuous
metallic matrix, wherein the first hard particles are at least one
of transition metal carbide particles and boron nitride particles,
and the total concentration of any first hard particles and blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts in the first layer is 25
to 85 volume percent based on the total volume of the first layer;
and a second layer metallurgically bonded to at least a portion of
the first layer, the second layer comprising a second continuous
metallic matrix, and at least one of second hard particles, blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts embedded in the second
metallic matrix, wherein the second hard particles are at least one
of transition metal carbide particles and boron nitride particles;
and wherein at least 50 volume percent of the second hard particles
embedded in the second continuous metallic matrix have a mesh size
of -10 to +400, at least 50 volume percent of the total volume of
any uncoated blocky diamond particles, cubic boron nitride
particles, and TSP diamond embedded in the second metallic matrix
have a toughness index of at least 35, the total concentration of
second hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the second layer is 10 to 50 volume percent
based on the total volume of the second layer, the total
concentration of blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the second layer is 0.5 to 20 volume percent
based on the total volume of the second layer, and at least 50
volume percent of the total volume of blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts embedded in the second continuous
metallic matrix has a size in the range of -10 mesh to 0.01 micron.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation application
claiming priority under 35 U.S.C. .sctn.120 to co-pending U.S.
application Ser. No. 12/488,167, filed on Jun. 19, 2009, which
patent application is hereby incorporated herein by reference in
its entirety.
BACKGROUND OF THE TECHNOLOGY
[0002] 1. Field of Technology
[0003] The present disclosure relates to multilayer overlays
providing corrosion, erosion and/or abrasion resistance to surfaces
of articles of manufacture. The present disclosure also relates to
methods for applying multilayer overlays to article surfaces,
wherein the overlays provide resistance to corrosion, erosion,
and/or abrasion.
[0004] 2. Description of the Background of the Technology
[0005] For many years, attempts have been made to reduce wear
experienced by pipes, valves, gaskets, and other material flow
parts in energy systems, refineries, coke plants, and chemical
production facilities, as well as by components that handle or
contact abrasive materials. Examples of such parts include pipe,
valves, and other parts subjected to a flow of highly abrasive oil
sands in energy production systems, or subjected to a flow of
highly corrosive chemicals in chemical production plants. Other
examples of such parts include excavating bucket teeth, grader
blades, and hammers. The conditions promoting wear of such parts
can be abrasive, erosive, and/or chemical in nature, and can be
extremely aggressive. The nature of material flow parts, for
example, often makes servicing and replacing them difficult, and
the process downtime and man-hours associated with repairing or
replacing parts in these systems can be very costly. Therefore,
substantial efforts have been made to produce material flow parts
for these applications that can better withstand the aggressive
corrosive, erosive, and/or abrasive wear conditions to which the
parts are subjected.
[0006] Materials including hard particles in a metallic matrix have
been proposed for reducing the wear of surfaces of metallic parts.
For example, Canadian patent application no. 2,498,073 describes a
wear resistant material composed of boron carbide particles in a
metal matrix, wherein the material is applied to the interior
surface of a fluid conducting part. Also, Canadian patent
application no. 1,018,474 describes a wear resistant material
composed of conventional synthetic industrial diamond in an
electroplated nickel matrix that is applied to a surface of a part
to inhibit wear. The hard carbide and diamond particles in these
prior art material provide wear resistance, and the matrix material
provides toughness and allows the wear resistant particles to be
securely associated with the surfaces to be protected from
wear.
[0007] Diamond is the hardest and most chemically inert material
known and has been used in some applications taking advantage of
its substantial resistance to wear. Industrial diamond and tungsten
carbide particles have been used in the superabrasives industry for
many years. For example, combinations of tungsten carbide and
conventional grit-size industrial diamond particles have been
embedded in a metallic matrix such as cobalt or iron to provide
materials for grinding wheels and saw blades. As is known in the
art, "industrial diamond" refers to small diamond particles that
are often synthetic, have no value as gemstones, and are used in
the cutting tool, abrasives, construction, and other industries.
The application of conventional industrial diamond to provide wear
resistance has been extended to the fabrication of highly wear
resistant parts composed of a polycrystalline diamond layer bonded
to a tungsten carbide matrix material substrate.
[0008] Mined diamond has been available for industrial use since
the early 1900's and became a material of strategic importance in
the 1940's. Given the intrinsic value of diamond, efforts have been
made for over 200 years to synthetically produce diamond. In 1797,
Tennant demonstrated that diamond is a high density form of carbon,
and it was postulated that subjecting common forms of carbon to
pressure might produce diamond. Over 100 years ago, Hannay reported
successfully producing diamond by sealing organic material and
lithium into tubes and heating them to very high temperature. In
the late 19th century, Moissan used the known solubility of carbon
in solid iron to attempt diamond synthesis by quenching a
high-temperature carbon/iron solution in water. The pressure
generated by contraction of the iron on cooling was claimed to
produce diamond. Although many additional attempts to produce
diamond in the laboratory were made over the years, it is believed
that until the 1950s those attempts were unsuccessful given the
intrinsic difficulty of replicating the conditions under which
diamond forms naturally. First, extremely high pressure is needed
to achieve the compact, strongly bonded structure of diamond.
Second, even when the extreme pressure necessary is achieved, very
high temperature also is required so that the conversion to diamond
occurs at a useful rate. Third, even when the pressure and
temperature conditions are achieved, only very small diamond grains
are produced. Achieving a large single crystal diamond requires
meeting even further, more extensive conditions.
[0009] By 1941, the General Electric, Carborundum, and Norton
companies and P. S. Bridgeman, a well known researcher in the field
of high pressure, agreed to jointly investigate diamond synthesis,
but the effort was discontinued prematurely due to the war. The
parties did report some success in that they claimed to have
subjected graphite at almost half a million psi to a temperature of
3000.degree. C. for a few seconds through a thermite reaction. In
1951, General Electric formed a high pressure diamond group that
came to include researchers H. A. Nerad, F. P. Bundy, H. M. Strong,
H. T. Hall, R. H. Wentorf, J. E. Cheney, and H. P. Bovenkerk. On
Dec. 16, 1954, Hall successfully obtained synthetic diamonds, and
he duplicated his success in several runs over the next two weeks.
During the succeeding few months, the GE group worked out the
details of Hall's synthesis process. The first public announcement
of success occurred in 1955, listing the names of Hall, Strong, and
Wentorf. At the same time, both the DeBeers company and researchers
in the USSR also reported the successful synthesis of diamond,
although the initial U.S. patent on a process for producing
synthetic diamond was awarded to General Electric.
[0010] Many additional processes for preparing synthetic diamond
have been developed since the successes of General Electric and
Hall. In certain of these processes, the nucleation and growth of
diamond crystals is achieved under relatively low pressure and
temperature conditions. The production of synthetic industrial
diamond has now advanced to the point that the quantity of
synthetic industrial diamond produced each year far exceeds the
amount of mined industrial diamond. General Electric exited the
commercial synthetic diamond business in 2003, when its
superabrasives business was sold and began operations as Diamond
Innovations. Diamond Innovations, Element Six, and Iljin Diamond,
along with a number of smaller producers, make up the current
primary players in the industrial diamond industry. The successful
and large-scale production of synthetic diamond has made the
material generally available at a cost justifying its use in
industrial and other applications.
[0011] Given the hardness and wear resistance of industrial diamond
and its present commercial availability, it would be advantageous
to provide materials including industrial diamond that may be
applied to surfaces of metallic parts to improve resistance to
corrosion, erosion, and abrasion.
SUMMARY
[0012] One non-limiting aspect according to the present disclosure
is directed to a wear resistant multilayer overlay. The wear
resistant multilayer overlay includes a first or inner layer
including a first continuous metallic matrix and at least one of
first hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the first continuous metallic matrix. The
first hard particles are at least one of transition metal carbide
particles and cubic boron nitride particles. The wear resistant
multilayer overlay also includes a second or outer layer that is
metallurgically bonded to at least a portion of the first or inner
layer. The second or outer layer includes a second continuous
metallic matrix, and at least one of second hard particles, blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts embedded in the second
continuous metallic matrix. The second hard particles are at least
one of transition metal carbide particles and boron nitride
particles.
[0013] Another non-limiting aspect according to the present
disclosure is directed to a wear resistant multilayer overlay
including a first or inner layer comprising a first continuous
metallic matrix and at least one of first hard particles, blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts embedded therein. The
first hard particles are at least one of transition metal carbide
particles and boron nitride particles, and the at least one of
first hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts are dispersed and embedded in the first continuous
metallic matrix in a concentration of 25 to 85 volume percent based
on the total volume of the first layer. The wear resistant
multilayer overlay also includes a second or outer layer
metallurgically bonded to at least a portion of the first or inner
layer. The second or outer layer includes at least one of second
hard particles, blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts embedded in the second continuous metallic matrix. The
second hard particles are at least one of transition metal carbide
particles and boron nitride particles. Preferably, the outer layer
includes second hard particles and at least 50 volume percent of
the second hard particles embedded in the second continuous
metallic matrix have a mesh size of -10 to +400. Also, preferably
at least 50 volume percent of any uncoated blocky diamond particles
and TSP diamond embedded in the second metallic matrix have a
toughness index of at least 35, and preferably at least 50. The
total concentration of second hard particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts embedded in the second or outer
layer is 10 to 80 volume percent, based on the total volume of the
second or outer layer. Also, the total concentration of any blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts embedded in the second or
outer layer preferably is 0.5 to 20 volume percent based on the
total volume of the second or outer layer, and at least 50 volume
percent of the total volume of any blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts embedded in the second continuous
metallic matrix preferably has a size in the range of -10 mesh to
0.01 micron.
[0014] A further non-limiting aspect according to the present
disclosure is directed to an article of manufacture including a
wear resistant multilayer overlay according to the present
disclosure disposed on at least a region of a surface of the
article. Certain non-limiting embodiments of the article of
manufacture may be selected from a pipe, a valve, a valve part, a
flange, a drill string casing stabilizer, a pump part, a hammer, a
drag line tooth, an excavating tooth, an excavating bucket part, a
road scraper part, a mixing blade, a drill, a cutter head, a cutter
tooth, and a container. One particular non-limiting embodiment of
an article of manufacture according to the present disclosure is a
pipe for transporting oil sands, wherein a wear resistant
multilayer overlay according to the present disclosure is disposed
on at least a region of an interior surface of the pipe that is
contacted by oil sands being transported through the pipe.
[0015] An additional non-limiting aspect according to the present
disclosure is directed to a method of improving the resistance of a
metallic surface to at least one of erosion, corrosion, and
abrasion by providing a wear resistant multilayer overlay according
to the present disclosure on at least a region of the metallic
surface. The method includes providing a first or inner layer on at
least a region of the metallic surface, and providing a second or
outer layer metallurgically bonded to at least a region of the
first or inner layer. The first or inner layer comprises at least
one of first hard particles, blocky diamond particles, non-blocky
diamond particles, TSP diamond, cubic boron nitride particles, and
PCD compacts dispersed and embedded in a first continuous metallic
matrix, wherein the first hard particles are at least one of
transition metal carbide particles and boron nitride particles. The
second or outer layer includes at least one of second hard
particles, blocky diamond particles, non-blocky diamond particles,
TSP diamond, cubic boron nitride particles, and PCD compacts
dispersed and embedded in the second continuous metallic matrix.
The second hard particles are at least one of transition metal
carbide particles and boron nitride particles.
[0016] In certain non-limiting embodiments of a method according to
the present disclosure, a first or inner layer and a second or
outer layer according to the present disclosure are deposited by a
welding process such as, for example, a process selected from MIG
welding, TIG welding, and plasma welding. Also, in certain
embodiments of a method according to the present disclosure, the
method provides a wear resistant multilayer overlay on at least a
region of a metallic surface of an article of manufacture selected
from a pipe, a valve, a valve part, a flange, a drill string casing
stabilizer, a pump part, a hammer, a drag line tooth, an excavating
tooth, an excavating bucket part, a road scraper part, a mixing
blade, a drill, a cutter head, a cutter tooth, and a container.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Features and advantages of certain non-limiting embodiments
of the overlays, methods, and articles described herein may be
better understood by reference to the accompanying drawings in
which:
[0018] FIG. 1 is a schematic cross-sectional illustration of a
non-limiting embodiment of a wear resistant multilayer overlay
according to the present disclosure; and
[0019] FIG. 2 is a schematic illustration of a non-limiting
embodiment of certain elements of a system for applying a wear
resistant multilayer overlay according to the present
disclosure.
[0020] FIG. 3 is a flow diagram illustrating certain steps of one
non-limiting process for applying a wear resistant multilayer
overlay according to the present disclosure using the apparatus
illustrated in FIG. 2.
[0021] The reader will appreciate the foregoing details, as well as
others, upon considering the following detailed description of
certain non-limiting embodiments of overlays, methods, and articles
according to the present disclosure. The reader also may comprehend
certain of such additional details upon carrying out or using the
overlays, methods, and articles described herein.
DETAILED DESCRIPTION OF CERTAIN NON-LIMITING EMBODIMENTS
[0022] In the present description of non-limiting embodiments,
other than in the operating examples or where otherwise indicated,
all numbers expressing quantities or characteristics of ingredients
and products, processing conditions, and the like are to be
understood as being modified in all instances by the term "about".
Accordingly, unless indicated to the contrary, any numerical
parameters set forth in the following description are
approximations that may vary depending upon the desired properties
one seeks to obtain in the present invention. At the very least,
and not as an attempt to limit the application of the doctrine of
equivalents to the scope of the claims, each numerical parameter
should at least be construed in light of the number of reported
significant digits and by applying ordinary rounding
techniques.
[0023] Any patent, publication, or other disclosure material, in
whole or in part, that is said to be incorporated by reference
herein is incorporated herein only to the extent that the
incorporated material does not conflict with existing definitions,
statements, or other disclosure material set forth in this
disclosure. As such, and to the extent necessary, the disclosure as
set forth herein supersedes any conflicting material incorporated
herein by reference. Any material, or portion thereof, that is said
to be incorporated by reference herein, but which conflicts with
existing definitions, statements, or other disclosure material set
forth herein is only incorporated to the extent that no conflict
arises between that incorporated material and the existing
disclosure material.
[0024] One aspect of the present disclosure is directed to a wear
resistant multilayer overlay. As discussed below, the overlay
according to the present disclosure resists corrosion, erosion,
and/or abrasion and may be applied to metallic surfaces of articles
subjected to chemically corrosive, erosive, and/or physically
abrasive conditions. These conditions are encountered, for example,
by the following parts: parts for conducting fluids, including
corrosive fluid materials such as hot, caustic materials; parts for
conducting, transporting, or holding slag or coke particles; parts
for conducting liquids in oil producing facilities; parts for
conducting physically abrasive materials such as, for example, tar
sands and oil sands; parts of crushing, grinding, excavating,
and/or grading apparatuses; and parts of material transport
apparatuses for transporting or conveying abrasive materials.
[0025] As used herein in the following description of the invention
and in the appended claims, the following terms are understood to
have the following meanings:
[0026] The words "and/or" mean that either of the items preceding
and following the words term may be present alone, or both of the
items may be present together.
[0027] "Blocky diamond particles" has the meaning provided
below.
[0028] "Cubic boron nitride", which also is referred to as "CBN",
is a manufactured product that does not occur in nature and is
produced in a process similar to that used to produce industrial
diamond. In the process, hexagonal boron nitride powder is
subjected to ultrahigh pressure and high temperature and is
converted to the cubic form. Cubic boron nitride is the second
hardest known substance.
[0029] "Mesh size" refers to the US Standard Sieve Series, which
corresponds to the number of wires per inch of screen used to
assess the size of the material. As such, larger numbers correspond
to smaller wire spacing on the mesh. A mesh size range such may be
represented as, for example, "-10 to +400 mesh", which also may be
presented herein in the format "10/400". A sample having a mesh
size range of 10/400 means that a 10 mesh screen is the largest
screen size through which all of the sample theoretically passes
through, and a 400 mesh screen is the largest screen through which
none of the sample theoretically passes through, although certain
allowable maximum percentages of oversized and undersized particles
are set forth in ANSI specifications. Those having ordinary skill
can readily determine the mesh size of a particular sample using
conventional techniques and equipment. With regard to the present
invention, the mesh size of a diamond sample is determined pursuant
to specification ANSI B74.16-2002, "Checking the Size of Diamond
Abrasive Grain", for mesh sizes 8/10 through 325/400, and pursuant
to specification ANSI B74.20-1997, "Grading of Diamond Powder in
Sub-Sieve Sizes", for micron powders of sizes 0-1 micron through
54-80 micron.
[0030] "Metallic" means metal-containing and encompasses, for
example, metals and metal alloys.
[0031] "Multilayer" means including two or more layers.
[0032] "Overlay" means a metallic structure of at least 3 mm that
is molecularly bonded to a base material.
[0033] A "polycrystalline diamond compact" or "PCD compact" refers
to a compact composed of a layer of polycrystalline diamond on a
tungsten carbide substrate. Polycrystalline diamond compacts are
synthesized by agglomeration of diamond micropowder and a hard
alloy substrate under conditions of ultrahigh pressure and high
temperature.
[0034] "TSP diamond" refers to thermally stable polycrystalline
diamond, which comprises synthetic diamond grown in a cell with the
aid of a metallic catalyst, sintered together under high pressure
and temperature, and then leached to remove residual metal. TSP
diamond is manufactured in a variety of shapes (for example, cubes
and spheres) and sizes, and is available commercially from, for
example, Element Six (New York, N.Y.) and Diamond Innovations
(Worthington, Ohio).
[0035] "Wear resistant" is the characteristic of having relatively
substantial resistance to wear from corrosion, erosion, and/or
abrasion.
[0036] One non-limiting embodiment of a wear resistant multilayer
overlayer according to the present disclosure is described in
conjunction with FIG. 1. Multilayer overlay 100 includes two
distinct layers and is applied to a base material 110 to protect
all or a region of the surface 112 of the base material 110 from
corrosive, erosive, and/or abrasive conditions. The base material
110 and, consequently, the surface 112 may be, for example, a metal
or a metal alloy. Non-limiting examples of possible base materials
include carbon steel, stainless steel, and nickel and cobalt base
superalloys. The portion of the base material 110 shown in FIG. 1
may be representative of a portion or region of, for example, a
pipe, a valve, a valve part, a flange, a drill string casing
stabilizer, a pump part, a hammer, a drag line tooth, an excavating
tooth, an excavating bucket part, a road scraper part, a mixing
blade, a drill, a cutter head, a cutter tooth, or a container.
[0037] Multilayer overlay 100 includes an inner (first) layer 120
and an outer (second) layer 122. The outer layer 122 is disposed on
at least a region of the inner layer 120. Although the embodiment
illustrated in FIG. 1 includes only inner and outer layers 120 and
122, it will be understood that certain other embodiments of the
wear resistant multilayer overlay according to the present
disclosure may include one or more additional layers disposed
exterior to the outer layer 122. The inner layer 120 may include
one or more of first hard particles, blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts. In multilayer overlay 100, for
example, inner layer 120 is a layer including first hard particles
124 and at least one of blocky diamond particles, non-blocky
diamond particles, TSP diamond, cubic boron nitride particles, and
PCD compacts 125 dispersed and embedded in a first continuous
metallic matrix 126. The first hard particles 124 may include one
or more of transition metal carbide particles and boron nitride
particles. Examples of possible transition metal carbide particles
include particles of carbides of one or more of titanium, vanadium,
chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium,
zirconium, niobium, molybdenum, ruthenium, rhodium, palladium,
silver, cadmium, hafnium, tantalum, and tungsten.
[0038] The first continuous metallic matrix is a metal or metal
alloy, and non-limiting examples of possible metal alloys from
which the first metallic matrix is comprised include carbon steel,
stainless steel, and nickel-chromium superalloys. If the surface on
which the inner layer is disposed is composed of carbon steel, then
the first continuous metallic matrix preferably also is a carbon
steel. If the surface on which the inner layer is disposed is
composed of stainless steel, then the first continuous metallic
matrix preferably also is a stainless steel.
[0039] Again referring to FIG. 1, outer layer 122 is disposed on
and metallurgically bonded to at least a region or portion of inner
layer 120. Outer layer 122 includes one or more of second hard
particles, blocky diamond particles, non-blocky diamond particles,
TSP diamond, cubic boron nitride particles, and PCD compacts. In
multilayer overlay 100, for example, second hard particles 128 in
the form of transition metal carbide particles, and at least one of
blocky diamond particles, non-blocky diamond particles, TSP
diamond, cubic boron nitride particles, and PCD compacts 130 are
dispersed and embedded in a second continuous metallic matrix 132.
Examples of possible transition metal carbide particles include
particles of carbides of one or more of titanium, vanadium,
chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium,
zirconium, niobium, molybdenum, ruthenium, rhodium, palladium,
silver, cadmium, hafnium, tantalum, and tungsten.
[0040] The second continuous metallic matrix also is a metal or
metal alloy. Similar to the first continuous metallic matrix,
non-limiting examples of possible metal alloys from which the
second continuous metallic matrix 132 is comprised include carbon
steel, stainless steel, and nickel-chromium superalloys. If the
first continuous metallic matrix is a carbon steel, then the second
continuous metallic matrix preferably also is a carbon steel. If
the first continuous metallic matrix is a stainless steel, then the
second continuous metallic matrix preferably also is a stainless
steel.
[0041] It will be understood that in certain non-limiting
embodiments of an overlayer according to the present disclosure,
the inner layer 120 and the outer layer 122 of the multilayer
overlay 100 each include a discontinuous phase of hard particles
(for example, transition metal carbides, boron nitride particles,
cubic boron nitride particles, blocky diamond particles, non-blocky
diamond particles, and/or TSP diamond) dispersed and embedded in a
continuous matrix of a metal or metal alloy.
[0042] In certain non-limiting embodiments, the wear resistant
multilayer overlay 100 includes an inner layer 120 having a
thickness of 3 to 15 mm. Also, in certain non-limiting embodiments,
the wear resistant multilayer overlay 100 includes an outer layer
122 having a thickness of 3 to 8 mm. In other non-limiting
embodiments, the overlay 100 includes both an inner layer 120
having a thickness of 3 to 15 mm, and an outer layer 122 having a
thickness of 3 to 8 mm. It will be understood, however, that the
inner layer, outer layer, and any additional layer or layers of the
wear resistant multilayer overlays according to the present
disclosure may have any thickness suitable for the desired
application, so long as the entire overlayer thickness is at least
3 mm. For example, layer thicknesses may be greater when the
overlay is intended for use under extremely corrosive, erosive,
and/or abrasive conditions. Thicker layers provide overlays
allowing for a longer service life of the treated part before it is
necessary to re-apply the overlay or replace the treated part.
[0043] The identity, concentration, and size of the first hard
particles 124 and any blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts 125 embedded in the inner layer 120 are selected to
provide acceptable wear resistance to the inner layer 120 in the
event that the outer layer wears away or is absent at one or more
regions of the overlay 100. In addition, a certain concentration of
the first hard particles 124, if present in the overlay, may be
embedded in both the inner layer 120 and the outer layer 122,
across the interface between the layers, thereby enhancing the
strength of the bond between the inner layer 120 and the outer
layer 122 to better resist deterioration of the overlay 100. In
certain embodiments, the total concentration of first hard
particles 124 and blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts 125 embedded in the first continuous metallic matrix 126
is 25 to 85 volume percent, more preferably is 25 to 75 volume
percent, and even more preferably is 25 to 70 volume percent, each
based on the total volume of the inner layer 120. In certain other
embodiments, the total concentration of first hard particles 124
and blocky diamond particles, non-blocky diamond particles, TSP
diamond, cubic boron nitride particles, and PCD compacts 125
embedded in the first continuous metallic matrix 126 is at least 30
volume percent based on the total volume of the inner layer 120.
Also, in certain embodiments, the overlay includes first hard
particles 124 and at least a portion of the first hard particles
124 embedded in the first continuous metallic matrix 126 are
tungsten carbide particles.
[0044] As noted, in certain non-limiting embodiments, the inner
layer 120 may include blocky diamond particles and/or non-blocky
diamond particles and/or TSP diamond and/or cubic boron nitride
particles and/or PCD compacts. In such embodiments, the total
concentration of blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts 125 embedded in the inner layer 120 may be up to 20 volume
percent based on the total volume of the inner layer 120. In
certain other embodiments, the total concentration of blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts 125 embedded in the inner
layer 120 may be 0.5 to 20 volume percent based on the total volume
of the inner layer 120.
[0045] In certain non-limiting embodiments of the multilayer
overlay 100, at least 50 volume percent, and more preferably at
least 80 volume percent, of any first hard particles 124 dispersed
in the first continuous metallic matrix 126 of the inner layer 120
have a mesh size in the range of -10 to +400 mesh. In a more
preferred non-limiting embodiment, at least 50 volume percent of
any first hard particles 124 dispersed in the first continuous
metallic matrix 126 of the inner layer 120 have a mesh size in the
range of -30 to +400 mesh. In certain non-limiting embodiments, the
first hard particles 124 included in the inner layer 120 include
tungsten carbide particles having a mesh size of 14/20, 20/30,
30/40, or 40/50 mesh.
[0046] Also, in certain non-limiting embodiments of the multilayer
overlay 100, at least 50 percent of the total volume of any blocky
diamond particles, non-blocky diamond particles, TSP diamond, cubic
boron nitride particles, and PCD compacts dispersed in the first
continuous metallic matrix 126 of the inner layer 120 have a size
in the range of -10 mesh to +0.01 micron (linear diameter). As is
known in the art, TSP diamond and PCD compacts are available as
formed structures in a variety of shapes. Any suitable shape of TSP
diamond, cubic boron nitride particles, and PCD compacts may be
used in the overlays of the present disclosure. With regard to TSP
diamond, cubic and spherical shapes are preferred. In certain
non-limiting embodiments, the inner layer 120 includes TSP diamond
and/or cubic boron nitride particles and/or PCD compacts having a
mesh size of 10/14, 14/20, 20/30, or 30/40 mesh. If the inner layer
120 includes blocky diamond particles and/or non-blocky diamond
particles, the mesh sizes of the particles may be, for example,
30/40, 40/50, 50/60, 60/80, 80/100, 100/120, 120/140, 140/170,
170/200, 200/230, 230/270, 270/325, or 325/400 mesh.
[0047] As is known to those having ordinary skill in the field of
industrial diamond manufacture, blocky diamond particles refers
specifically to single crystal diamond particles having a well
structured and generally uniform cuboidal or cubo-octohedral
crystal shape. Also, as used herein, blocky diamond particles
consist of single crystals have a planar mode aspect ratio in the
range of 1.5:1 to 1:1 (inclusive) and, thus, have or approximate a
cuboidal or "blocky" crystal shape. The present inventor observed
that blocky diamond particles have significantly higher strength
and toughness than non-blocky diamond particles when the diamond
particles are included in the dispersed (discontinuous) phase of a
metallic wear resistant overlay. Also, in certain non-limiting
embodiment described herein, part or all of the content of uncoated
blocky diamond particles, cubic boron nitride particles, and TSP
diamond have a toughness index of at least 35, and preferably at
least 50, as evaluated using a conventional friability test known
in the industry, in which a specially designed capsule is loaded
with 2 carats of a particulate sample and a number of 1/4 inch
stainless steel ball bearings and is reciprocated along a fixed
path at a fixed rate for a fixed time. The percentage of the sample
that is left on a screen of selected mesh size after the testing is
conducted is designated the "toughness index". Thus, a higher
toughness index reflects that a greater percentage of the
particulate diamond sample remained on the screen. A higher
toughness index corresponds to a tougher, less friable sample.
Equipment for determining the toughness index is available from,
for example, American Superabrasives Corp., Shrewsbury, N.J.
Furthermore, blocky diamond particles used in the overlays
according to the present disclosure preferably have bulk density of
1.96 to 2.08 as determined pursuant to specification ANSI
674.4-1992 (R 2002), "Bulk Density of Abrasive Grains".
[0048] The present inventor also observed that blocky diamond
particles have a significantly lower propensity to dislodge from
the metallic matrix (i.e., erode or spall) than non-blocky diamond
particles when incorporated in a multilayer metallic overlay
according to the present disclosure. In other words, the present
inventor determined that blocky diamond particles are significantly
less likely to fracture or spall under strain than non-blocky
diamond particles when included in the dispersed phase of wear
resistant overlays according to the present disclosure. The
significantly reduced propensity of blocky diamond particles to
fracture or spall when incorporated in such overlays was observed
to significantly improve the integrity and substantially enhance
the wear resistance and service life of such overlays relative to
materials including conventional industrial diamond. Conventional
industrial diamond is typically non-blocky in form and does not
have the characteristics discussed herein for blocky diamond
particles. To the inventor's knowledge, a wear resistant overlay
comprising blocky diamond particles in a metallic matrix material
has not been available and has not been proposed previously.
[0049] As discussed above, in certain non-limiting embodiments of
the multilayer overlay 100, the outer layer 122 includes second
hard particles 128 and at least one of blocky diamond particles,
non-blocky diamond particles, TSP diamond, cubic boron nitride
particles, and PCD compacts 130 dispersed and embedded in the
second continuous metallic matrix material 132. The identity,
concentration, and size of the second hard particles 128 embedded
in the outer layer 122 are selected to provide acceptable wear
resistance to the outer layer 122. In certain embodiments, the
combined concentration of second hard particles 128, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts 130 embedded in the second
continuous metallic matrix 132 is 10 to 85 volume percent, more
preferably is 10 to 50 volume percent, and even more preferably is
25 to 50 volume percent, each based on the total volume of the
outer layer 122.
[0050] In certain non-limiting embodiments of the multilayer
overlay 100, at least 50 volume percent, and more preferably at
least 80 volume percent, of any second hard particles 128 dispersed
in the second continuous metallic matrix 132 of the outer layer 122
have a mesh size in the range of -10 to +400 mesh. In a more
preferred non-limiting embodiment, at least 50 volume percent of
any second hard particles 128 dispersed in the second continuous
metallic matrix 132 of the outer layer 122 have a mesh size in the
range of -30 to +400 mesh. Also, in certain non-limiting
embodiments of the multilayer overlay 100, at least 50 percent of
the total volume of blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and PCD
compacts dispersed in the second continuous metallic matrix 132 of
the outer layer 122 have a size in the range of -10 mesh to +0.01
micron (linear diameter). As is known in the art, TSP diamond,
cubic boron nitride, and PCD compacts are available as formed
structures that may have any of a variety of shapes. As discussed
above, any suitable shape of TSP diamond, cubic boron nitride
particles, and PCD compacts may be used. With regard to TSP
diamond, cubic and spherical shapes are preferred. In certain
additional non-limiting embodiments of the multilayer overlay 100,
the outer layer 122 includes one or more of blocky diamond,
non-blocky diamond, TSP diamond, cubic boron nitride particles, and
PCS compacts in any of the mesh sizes included in the inner layer
120, as discussed above.
[0051] Optionally, a portion or all of the diamond particles, cubic
boron nitride particles, and TSP diamond included in the inner
layer 120 and outer layer 122 of the multilayer overlay 100 may be
coated with at least one metal or alloy to improve bond strength
with the continuous metallic matrix in which they are dispersed. In
one non-limiting embodiment of the multilayer overlay 100, at least
a portion of the blocky diamond particles, non-blocky diamond
particles, TSP diamond, cubic boron nitride particles, and/or PCD
compacts in at least one of the inner layer 120 and outer layer 122
are coated with titanium, a titanium alloy, nickel, or
nickel/chromium to improve bond strength with the continuous
metallic matrix in which they are dispersed.
[0052] A non-limiting example of a system and method for applying
the wear resistant multilayer overlay according to the present
disclosure is described below in conjunction with FIG. 2. In that
non-limiting example, both first and second continuous metallic
matrices are weld deposits deposited using, for example, MIG, TIG,
or plasma welding techniques, and that may be selected from carbon
steel, stainless steel, and nickel-base superalloys.
[0053] In one particular non-limiting embodiment according to the
present disclosure, the wear resistant multilayer overlay according
to the present disclosure includes an inner (first) layer
comprising 25 to 85 volume percent first hard particles (based on
the volume of the inner layer 120) dispersed and embedded in a
first continuous metallic matrix. The first hard particles may be
at least one of transition metal carbide particles and boron
nitride particles, and the first continuous metallic matrix is
deposited as a weld deposit. An outer (second) layer is
metallurgically bonded to at least a portion of the inner layer and
comprises second hard particles and at least one of blocky diamond
particles, cubic boron nitride particles, and TSP diamond, which
are dispersed and embedded in a second continuous metallic matrix
that also is deposited as a weld deposit. At least 50 volume
percent of the second hard particles 124 embedded in the second
continuous metallic matrix have a mesh size within the range of -10
mesh to +400 mesh, and at least 50 volume percent of the total
volume of blocky diamond particles, cubic boron nitride particles,
and TSP diamond embedded in the second continuous metallic matrix
has a size within the range of -10 mesh to 0.01 micron. Preferably,
at least 50 volume percent of the total volume of uncoated blocky
diamond particles, cubic boron nitride particles, and TSP diamond
embedded in the second metallic matrix have a toughness index of at
least 35, and preferably at least 50. The total concentration of
second hard particles, blocky diamond particles, cubic boron
nitride particles, and TSP diamond embedded in the outer layer 122
is 10 to 50 volume percent based on the total volume of the outer
layer, and the total concentration of blocky diamond particles,
cubic boron nitride particles, and TSP diamond embedded in the
outer layer 122 is 0.5 to 20 volume percent based on the total
volume of the outer layer 122. The first and second continuous
metallic matrices are weld deposits deposited by one of a MIG, TIG,
and plasma welding technique, and the weld deposits are selected
from carbon steel, stainless steel, and nickel-base
superalloys.
[0054] Again referring to FIG. 1, the multilayer overlay 100 and
other multilayer overlays according to the present disclosure may
be applied to a base material using an apparatus including a
welding device and a conventional vibratory feed mechanism for
metering particulate materials to the weld deposit as it is
deposited. One possible non-limiting system for applying a wear
resistant multilayer overlay according to the present disclosure is
illustrated in FIG. 2, wherein apparatus 200 includes MIG welding
nozzle 210 and vibratory feed device 212. Welding nozzle 210 is
associated with a welding device (other parts of the welding device
are not shown in FIG. 2) and deposits a metal or metal alloy weld
deposit on surface 218 of base material 220 as the metallic matrix
material 214. Vibratory feed device 212 meters particulate material
including metal carbide, boron nitride, blocky diamond, non-blocky
diamond, TSP diamond, cubic boron nitride particles, and/or PCD
compacts 216. Although a MIG welding system is preferred, other
welding systems, such as, for example, plasma and TIG welding
systems, may be utilized. Welding nozzle 210 deposits the metal or
metal alloy matrix material 214 in a molten form on surface 218.
The particulate material 216 is fed to the surface 218 simultaneous
with the matrix material 214 and becomes dispersed and embedded
within the matrix material 214. Given that metal carbide, boron
nitride, cubic boron nitride, and the various diamond materials
have very high melting temperatures, they remain in solid form and
do not melt when contacting the molten matrix material 210.
[0055] The matrix material 214 applied to surface 218 to form the
first layer 320 of the multilayer overlay is a material that is
compatible with the base material 220. As used in that context, a
"compatible" material is one that forms a suitably strong
metallurgical bond with the base material and does not form alloys
or solid mixtures with the base material that exhibit unacceptable
mechanical characteristics, corrosion, or other properties in the
context of the particular application. For example, the matrix
material may be selected from carbon steel, stainless steel,
Inconel alloys (a family of austenitic nickel-chromium-based
superalloys), or another suitable metal or metallic alloy that will
produce an acceptable layer when combined with the specific
particulate material dispersed and embedded within it. Those having
ordinary skill will be able to select a suitable matrix material
for the inner layer 230 that is compatible with the base material
220 and that will form a suitable layer with the particulate
material 216.
[0056] Vibratory feed device 212 may have a conventional design. As
shown in FIG. 2, an embodiment of vibratory feed device 212
includes inverted conical hopper 240 in which particulate material
216 is disposed. Particulate material 216 passes to feeder trough
242 by action of gravity. Vibratory drive motor 244 vibrates feeder
trough 242 and causes particulate material 216 to enter metering
nozzle 246, pass through metering tube 248, and drop onto and
disperse within molten matrix material 214 on surface 218. The
guide end 249 of metering tube 248 is secured to welding nozzle 210
by bracket 250 so that particulate material 216 is deposited
immediately after molten matrix material 214 is deposited on
surface 218. Although FIG. 2 depicts a particular design of
vibratory feed device to meter particulate material 216, it will be
understood that any suitable vibratory feed device may be used and,
more generally, that any method, system, or device for suitably
metering particulate material to a surface may be used. The inner
layer 230 is applied to surface 218 by translating the apparatus
200 and/or the base material 220 so that relative motion occurs.
The apparatus 200 deposits a strip or band of the inner layer 230
of the multilayer overlay along the surface 218, covering a width
of the surface dependent on various parameters including, for
example, the design of the weld nozzle 210 and other parameters of
the welding process. Suitable relative motion of the apparatus 200
and the base material 220 in a pattern wherein adjacent strips or
bands of the first layer 230 are deposited on the surface 218 may
be used to cover a target region of the surface 218.
[0057] The vibratory feed device 212 meters the particulate
material 216 to the surface 218 at a rate (volume/time) to provide
the desired saturation level of the matrix material 214. As is
conventional with vibratory feeder devices, the flow of particulate
material from the feeder device can be controlled by adjusting the
degree of vibrational energy applied to the particulate material.
The molten matrix material 214, however, will only be able to
accommodate a particular maximum concentration of particulate
material. The desired concentration of a particular particulate
material within a particular layer of the multilayer overlay will
depend on a variety of factors, including the target application
for the material, the identities of the particulate and matrix
materials, and the thickness of the individual layers. For example,
an embodiment of a multilayer overlay according to the present
disclosure adapted for application to interior surfaces of pipes,
valves, flanges, and related parts for conducting tar sands or oil
sands, which are highly abrasive, will require a relatively high
concentration of particulate material in a particular layer. The
interior surfaces of like parts for transporting relatively
non-abrasive oil field or plant flow can be coated with layers
including a relatively lower concentration of particulate
material.
[0058] Again referring to FIG. 2, the apparatus 200 is depicted
with only a single vibratory feed device 212, which includes a
single conical hopper 240, feeder trough 242, drive motor 244,
metering tube 248, and metering nozzle 246. However, it will be
apparent that the apparatus 200 may include multiple vibratory feed
devices, each for metering out a different particulate material
into the weld deposit. Therefore, for example, if the layer being
applied includes a first predetermined concentration of tungsten
carbide particles and a second predetermined concentration of
blocky diamond particles, a separate vibratory feed device may be
provided for feeding each of the materials onto the molten weld
deposit, and each of the separate vibratory feed devices will be
set up to feed the particular particulate material at the desired
rate to achieve the respective predetermined concentration in the
applied layer of the overlay. Other arrangements for feeding the
particular particulate materials to the molten weld deposit to
achieve the desired particulate concentrations in the applied layer
of an overlay according to the present disclosure will be apparent
to those having ordinary skill in the welding art and are included
within the scope of the present invention.
[0059] With further reference to FIG. 2, due to the generally rapid
feed rate of the particulate material 216 and the effects of the
rapid cooling of the molten matrix material 214, an excess of
particulate material 216 may be supplied to the inner layer 230,
resulting in particulate material remaining on the exposed surface
of the inner layer 230. A second, outer layer of molten matrix
material is overlaid on top of the first layer using apparatus 200
by similar relative motion between the base material 220 and the
welding nozzle 210. Particulate material including, for example,
blocky diamond particles, cubic boron nitride particles, and/or TSP
diamond is introduced onto the molten weld deposit by vibratory
feed apparatus 212 so as to become dispersed and embedded in the
weld deposit, which solidifies to form an outer layer of the
multilayer overlay. Excess particulate material present on the
exposed surface of the inner layer will be incorporated into the
second layer during the second pass of the apparatus 200. In
addition to, for example, blocky diamond particles, cubic boron
nitride particles, and/or TSP diamond, the particulate material fed
from the vibratory feed apparatus 212 during the second pass of the
apparatus 200 may include, for example, one or more of transition
metal carbide particles and cubic boron nitride particles, which
also become dispersed and embedded in the outer layer of the
overlay. Applying the outer layer in a second pass of the apparatus
200 also may be beneficial as it anneals the inner layer, making
the inner layer less likely to crack in service.
[0060] The apparatus 200 schematically depicted in FIG. 2 may be
adapted to apply a wear resistant multilayer overlay according to
the present invention on any metallic surface by conducting at
least two welding passes with the apparatus to form an inner and an
outer layer of the overlay. The overlay may be formulated to
provide substantially improved resistance to corrosion, erosion,
and/or abrasion to the treated surface. In some circumstances, the
outer layer may require grinding of its exposed surface after its
application to thereby smooth the surface, remove oxidation formed
at high temperatures from the surface, and/or improve surface
finish.
[0061] Steps of a general process for applying the wear resistant
multilayer overlay according to the present disclosure using the
apparatus 200 described above and illustrated in FIG. 2 are
described below and illustrated by the flow diagram of FIG. 3. It
will be understood that the following steps are those of one
non-limiting example of a process for applying the overlays and are
not exclusive of the various processes that may be used to provide
overlays according to the present disclosure on surfaces. Also,
although the following non-limiting process describes applying an
overlay according to the present disclosure to a single surface of
a part, it will be understood that the process may be adapted to
apply the same or a different overlay according to the present
disclosure on more than one surface an/or on surface regions.
[0062] In a first process step, the part surface on which the
overlay is to be applied is visually inspected for defects or
damage. Any issues regarding the integrity or condition (appearance
of significant surface corrosion, for example) should be resolved
before proceeding to the next step. Corrosion, pitting, or other
physical defects apparent on the surface may prevent a suitably
strong bond from forming between the surface and the inner (first)
layer of the overlay.
[0063] In a second process step, the surface on which the overlay
is to be applied is cleaned to better ensure suitable bonding with
the inner layer of the overlay. The surface is cleaned with a
suitable degreasing agent. In some cases, the surface may have to
be grit blasted to condition the surface to assure adequate bonding
of the inner (first) layer. The part subsequently is heated in a
furnace at 500.degree. F. or, alternatively, the part surface is
heated with a "rosebud" heating tip to 500.degree. F. to achieve a
suitable temperature for deposition of the materials included in
the inner layer of the overlay.
[0064] In a third process step, a suitable welding wire is selected
for use in the apparatus for applying the overlay that is described
above and illustrated in FIG. 2. Those having ordinary skill may
select a suitable welding wire based on the material from which the
surface on which the overlay is to be applied is composed. Of
course, a suitable welding wire will deposit an alloy that is
compatible with the surface material and with the particulate
materials to be included in the layer. As discussed above, a
compatible alloy will forms a suitably strong metallurgical bond
with the surface material and will not form alloys or solid
mixtures with the surface material that exhibit unacceptable
mechanical characteristics, corrosion, or other properties in the
context of the particular application. For example, the matrix
material may be selected from carbon steel, stainless steel,
Inconel alloys, or another suitable alloy that provides an
acceptable inner layer of the overlay when combined with the
specific particulate material to be dispersed and embedded within
it. The selected welding wire may be mounted on a spool spindle of
the MIG welding device of the apparatus for applying the overlay
described above and depicted in FIG. 2. The correct wire guide is
installed on the welding device, and the weld wire is fed to the
welding nozzle of the welding device.
[0065] In a fourth process step, the parameters of the welding
operation are selected and set on the MIG welding device. The
welding wire feed rate and the welding device voltage or current,
depending on the type of equipment being used, are set so that a
weld deposit of suitable form is provided on the part surface.
Those having ordinary skill in welding may readily select suitable
feed rates, voltages, currents, and any other welding device
settings, based on the character of the surface and the welding
wire used. The ground of the welding device is clamped to a solid
metal piece, such as the part or the mounting fixture in which the
part is secured.
[0066] In a fifth process step, a translatable fabrication stand
programmable to move along X, Y, and Z axes is programmed for
travel speed and distance along each axis and is then properly
aligned with the welding device. As will be apparent to those
having ordinary skill in welding, the parameters of the
translatable fabrication stand are set so that when the part is
secured in a predetermined orientation and position on the stand,
the welding nozzle will move relative to the part in a pattern that
results in the desired overlay being properly formed on the part
surface.
[0067] In a sixth process step, the part is mounted in a fixture
attached to the translatable fabrication stand in the position and
orientation necessary so that the part moves with the stand
relative to the welding nozzle in the desired pattern.
[0068] In a seventh process step, the layers of the overlay are
applied to the surface using the welding device and the associated
vibratory feed device in conjunction with the fabrication stand.
The overlay application step may be broken down into a number of
individual sub-steps, as follows.
[0069] The temperature of the part mounted in the fixture is
checked. If the part's temperature is less than 450.degree. F., the
part surface is re-heated using a gas heating device with a
"rosebud" heating tip until the surface temperature is at least
475.degree. F. After confirming that the MIG welding device ground
is properly connected, the welding gas feed is turned on.
Particulate hard particles to be included in the weld deposit that
serves as the metallic matrix material are loaded into a hopper of
the vibratory feed device. As discussed above, those hard particles
include, but are not limited to, one or more of transition metal
carbide particles and boron nitride particles. If other particulate
materials such as any of blocky diamond particles, non-blocky
diamond particles, TSP diamond, cubic boron nitride particles, and
PCD compacts are to be included in the applied layer, those
materials are loaded into the hopper of second and, if needed,
additional vibratory feed devices. Once sufficient particulate
materials are loaded into the one or more vibratory feed devices
and the one or more vibratory feed devices are set to the proper
feed rates, the devices are switched on.
[0070] After ensuring that all operators and observers are wearing
appropriate masks and other safety equipment, the welding device is
switched on. The translatable fabrication stand is then switched
on, and the inner (first) layer of the overlay is deposited on the
surface in a first pass as the part moves past the welding nozzle
and the particulate metering nozzle. The welding device and feeder
devices are switched off, and the inner layer deposited in the
first pass is then inspected.
[0071] If the inner layer is acceptable, then the particulate
materials to be included in the outer (second) layer are loaded
into the hoppers of the one or more vibratory feed devices and the
devices are set to the appropriate feed rates to provide the
desired concentration of each material in the outer layer. As
discussed above, the materials that are embedded and dispersed
within the outer layer may include, for example, transition metal
carbide particles, boron nitride particles, blocky diamond
particles, non-blocky diamond particles, TSP diamond, cubic boron
nitride particles, and PCD compacts. The one or more vibratory feed
devices are then switched on. After again ensuring that all
operators and observers are wearing appropriate masks and other
safety equipment, the welding device and feeder devices are
switched on and the fabrication stand is activated to move the part
in the programmed pattern to apply the outer layer onto the inner
layer in a second pass of the welding device.
[0072] Once the inner and outer layers of the overlay have been
applied to the part surface, the part is allowed to cool. Small
parts may be placed in an insulated chamber to slow cooling and
inhibit thermal cracking. Large parts may be allowed to cool art
room temperature, without forced cooling. Those having ordinary
skill will be able to determine a suitable cooling regimen for a
particular part and overlay. Once the part has cooled, the overlay
may be inspected and may be further processed as needed to remove
any oxide scale and/or provide a desired surface finish on the
overlay.
[0073] A wear resistant multilayer overlay according to the present
disclosure reduces lost production time because it allows treated
surfaces to withstand wear up to many times longer. The substantial
increase in part service life provided by application of the
present overlays reduces equipment shutdown frequency, and also may
reduce the number of parts requiring servicing or replacement
during shutdown. The present overlays also may eliminate or reduce
the need for equipment rentals, insulation replacement, and
inspection frequency, and reduce the overall number of man-hours
necessary for maintenance and repair. In addition, material costs
may be reduced by dispensing with the need to completely refurbish
or replace parts and equipment after years of service. Instead, a
new wear resistant multilayer overlay according to the present
disclosure may be applied to worn parts and thereby render them
suitable for substantial further use.
[0074] Although the foregoing description has necessarily presented
only a limited number of embodiments, those of ordinary skill in
the relevant art will appreciate that various changes in the
details of the examples that have been described and/or illustrated
herein may be made by those skilled in the art, and all such
modifications will remain within the principle and scope of the
present disclosure as expressed herein and in the appended claims.
It will also be appreciated by those skilled in the art that
changes could be made to the embodiments above without departing
from the broad inventive concept thereof. It is understood,
therefore, that this invention is not limited to the particular
embodiments disclosed herein, but it is intended to cover
modifications that are within the principle and scope of the
invention, as defined by the claims.
* * * * *