U.S. patent application number 11/345641 was filed with the patent office on 2006-11-16 for selective reinforcement with metal matrix composites.
This patent application is currently assigned to Touchstone Research Laboratory, Ltd.. Invention is credited to Brian L. Gordon, James F. Witzgall.
Application Number | 20060254744 11/345641 |
Document ID | / |
Family ID | 37417984 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060254744 |
Kind Code |
A1 |
Gordon; Brian L. ; et
al. |
November 16, 2006 |
Selective reinforcement with metal matrix composites
Abstract
A selectively reinforced structure may be produced by embedding
at least two metal matrix composite tapes in a non-planar
relationship to one another and in a predetermined region of a
structure to selectively reinforce the structure. Further, a method
for selectively reinforcing a structure or part includes
positioning at least two metal matrix composite tapes in a
substantially fixed non-planar relationship in a predetermined
location within a mold and filling the mold with a material such as
a metal, metal alloy, polymer, foam, glass, or ceramic such that
the MMC tapes are embedded within the material. A reinforced
structure is produced that has at least two metal matrix composite
tapes selectively positioned within the structure.
Inventors: |
Gordon; Brian L.; (Wheeling,
WV) ; Witzgall; James F.; (Wheeling, WV) |
Correspondence
Address: |
PHILIP D. LANE
P.O. BOX 79318
CHARLOTTE
NC
28271-7063
US
|
Assignee: |
Touchstone Research Laboratory,
Ltd.
|
Family ID: |
37417984 |
Appl. No.: |
11/345641 |
Filed: |
January 31, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60593624 |
Jan 31, 2005 |
|
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|
Current U.S.
Class: |
164/98 |
Current CPC
Class: |
B22D 19/02 20130101;
B22D 19/14 20130101 |
Class at
Publication: |
164/098 |
International
Class: |
B22D 19/02 20060101
B22D019/02 |
Claims
1. A method for selectively reinforcing a structure, comprising the
steps of: positioning at least two metal matrix composite tapes
having a longitudinal axis, a planar surface, and a maximum width
within a mold such that the planar surfaces are substantially
mutually non-parallel and the longitudinal axes are substantially
mutually parallel; and filling the mold with a material, wherein
the at least two metal matrix composite tapes are embedded within
the material and extend within the material a distance of at least
five times the maximum width of the tape.
2. The method of claim 1, wherein the metal matrix composite tape
comprises aluminum oxide fibers in an aluminum matrix.
3. The method of claim 1, wherein the material is selected from the
group consisting of a metal, metal alloy, polymer, glass, foam, and
a castable ceramic.
4. The method of claim 1, wherein the metal matrix composite tape
comprises aluminum oxide fibers in an aluminum matrix and wherein
the material comprises aluminum.
5. A selectively reinforced structure comprising a body of material
and at least two metal matrix composite tapes, each having a
longitudinal axis, a planar surface, and a maximum width, wherein
the planar surfaces are substantially mutually non-parallel and the
longitudinal axes are substantially mutually parallel, and wherein
the at least two metal matrix composite tapes are embedded within
the material of the body and extend within the body a distance of
at least five times the maximum width of the tape.
6. The selectively reinforced structure of claim 5, wherein the
metal matrix composite tape comprises aluminum oxide fibers in an
aluminum matrix.
7. The selectively reinforced structure of claim 5, wherein the
aluminum oxide fibers are continuous fibers.
8. The selectively reinforced structure of claim 5, wherein the
body comprises a material selected from the group consisting of a
metal, metal alloy, glass, polymer, foam, and a castable
ceramic.
9. The selectively reinforced structure of claim 5, wherein the
metal matrix composite tape comprises aluminum oxide fibers in an
aluminum matrix and wherein the body material comprises aluminum.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/593,624, filed Jan. 31, 2005, which is herein
specifically incorporated by reference in its entirety.
SUMMARY OF THE INVENTION
[0002] The present invention is directed to selectively reinforced
structure where at least two metal matrix composite reinforcements
are maintained in a relatively fixed, non-planar relationship to
one another within the structure. In certain embodiments, a
selectively reinforced structure may include a body of material and
at least two metal matrix composite tapes, each having a
longitudinal axis, a planar surface, and a maximum width, wherein
the planar surfaces are substantially mutually non-parallel and the
longitudinal axes are substantially mutually parallel, and wherein
the at least two metal matrix composite tapes are embedded within
the material of the body and extend within the body a distance of
at least five times the maximum width of the tape. The metal matrix
composite tape may include aluminum oxide fibers in an aluminum
matrix. Further, the aluminum oxide fibers may be continuous
fibers. In certain embodiments, the body of the structure may be
include a material such as metal, metal alloy, glass, polymer,
foam, and a castable ceramic. Further, the metal matrix composite
tape may include aluminum oxide fibers in an aluminum matrix and
the body material of the structure may include aluminum.
[0003] Still further, the invention may include a method for
selectively reinforcing a structure. The method may include the
steps of positioning at least two metal matrix composite tapes
having a longitudinal axis, a planar surface, and a maximum width
within a mold such that the planar surfaces are substantially
mutually non-parallel and the longitudinal axes are substantially
mutually parallel; and filling the mold with a material, wherein
the at least two metal matrix composite tapes are embedded within
the material and extend within the material a distance of at least
five times the maximum width of the tape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a perspective view of I-beam end plugs.
[0005] FIG. 2 is a perspective view of an I-beam metal matrix
composite tape insert.
[0006] FIG. 3 is a perspective view a casting with metal matrix
composite reinforcement in an I-beam configuration.
[0007] FIG. 4 is a plot of flexural load vs. displacement curves
for unreinforced aluminum (A), square reinforced aluminum (B),
I-beam reinforced aluminum (C), and aluminum reinforced with
vertical, parallel metal matrix composite tapes (D).
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0008] Selective reinforcement of structure is a method by which
strength and stiffness of regions of the structure can be improved
by adding metal matrix composite (MMC) materials with higher
strength and stiffness in the desired amount where it is
beneficial. Accordingly, MMC tape may be incorporated in a
structure, thereby providing selectively strengthened regions.
Materials used for the structure may include but are not limited
to, metal, metal alloys, plastic, glass, ceramic, foams or other
moldable or castable materials. As used herein, a metal matrix
composite ("MMC") is a material made of continuous reinforcing
fibers in a matrix of metal where the continuous fibers are
infiltrated with the matrix metal. Fibers may include aluminum
oxide, glass, quartz, carbon, or other similar fibers. The matrix
metal may include any castable metal or metal alloy that is
compatible with the selected fibers. The matrix metal may include
aluminum, magnesium, copper, zinc, iron, and alloys thereof as well
as other metals known to be used in forming metal matrix composite
tapes. MMC tape made of aluminum oxide fibers in aluminum or
aluminum alloys is available under the name METPREG.RTM. from
Touchstone Research Laboratory, Ltd., Triadelphia, West Va.
[0009] Structures that incur concentrated loads usually require the
application of high margins of safety to the entire structure. This
requirement leads to an increase in overall weight and size of the
structure beyond what is needed by the bulk of the structure in
order to ensure adequate load-carrying capacity in the highly
stressed areas. Incorporating at least two MMC tapes in the body of
structure in a relatively fixed and substantially non-planar
relationship provides for enhanced physical properties, such as
increased stiffness. Typically, each MMC tape has thickness, a
width and a length. The width of the tape defines a planar surface
of the tape. A longitudinal axis extends along the length of the
tape and is parallel to the planar surface.
[0010] At least two MMC tapes are positioned within the body of a
structure such that the planar surfaces are substantially mutually
non-parallel and the longitudinal axes are substantially mutually
parallel. The particular non-parallel configuration for the MMC
tapes is not limited and may include any variety of non-parallel
relationships. The at least two metal matrix composite tapes are
embedded within the material of the body making up the structure
and extend within the body a distance of at least five times the
maximum width of the tape.
[0011] Selectively incorporating MMC tapes allows the designer and
fabricator the opportunity to add stronger MMC tape material in
specific regions of the structure to selectively reinforce the
structure. Providing accurate and precise positioning of the MMC
tape in the structure improves the ability to selectively reinforce
the structure. MMC tapes can be positioned and held in place during
the fabrication process of the structure. A method may include
inserting at least two MMC tapes in a relatively fixed and
non-planar relationship as discussed above in a predetermined
region of a structure to selectively reinforce the structure.
Another method may include positioning at least two MMC tapes in a
relatively fixed and non-planar relationship as described above in
a selected location within a mold and filling the mold with a
material around the positioned tapes such that the MMC tapes are
embedded within the material and thereby achieving selective
reinforcement of the structure defined by the mold. The filling
step may include, but is not limited to, a molding process, a
casting process, or other similar process for forming the material
around the MMC tape.
[0012] Holding the MMC tapes in a selected configuration may be
accomplished by using machined end plugs to position the tapes
within the mold while molten metal or other material that will make
up the structure is poured into the mold. The end plugs are
machined with non-parallel slots such that the ends of the MMC tape
may be inserted in the slots to hold the MMC tape in the desired
configuration within the mold. The end plugs may be made out a
material that is machinable and can hold the configuration of the
MMC tapes during the molding process. One such material for end
plugs includes graphite or other similar materials used in the
molding process. When the MMC tapes are inserted in the mold with
the end caps, gaps between the end caps and the mold allow for the
material to enter the mold and surround the MMC tapes.
[0013] For casting metals, the mold may be kept above the melting
temperature of the casting metal for several minutes in order to
achieve a good interface between the tape and casting metal. This
may be accomplished by holding the mold under the molten casting
metal or using an auxiliary heat source around the mold. While the
metal is still molten within the mold, the mold may be moved,
vibrated, or agitated to encourage encapsulation and wetting of the
tapes by the casting metal. The mold may then be removed from the
heat and subjected to directional cooling or quenching in order to
reduce the formation of shrinkage porosity within the casting, as
desired. The cast part may then be removed from the mold and
allowed to cool to room temperature before handling.
EXAMPLE
[0014] MMC tapes were positioned in castings in the form of a
square, an I-beam, and parallel rows within the cast part. The MMC
tape, which was manufactured in a separate process, consisted of
continuous Nextel 610 fibers in a matrix of pure aluminum, with the
fibers oriented along the length of the tape. The MMC tapes were
held in place by graphite blocks that had grooves machined into
them to hold the MMC tapes in the desired position. Multiple tapes
were stacked together in each position. For example the I-beam
reinforcement consisted of four tapes stacked together in each
segment of the I-beam. FIG. 1 shows the graphite end plugs 10 with
grooves 12 that were used to hold the tapes in the shape of an
I-beam-reinforcement. FIG. 2 shows a tape insert 14 where MMC tapes
16 were held together with very fine stainless steel wire 18 to
help keep the tapes positioned properly during the casting process.
The casting metal was pure aluminum and was inserted into the mold
by attaching a handle to the mold and submerging the mold into a
large crucible containing the molten aluminum. The mold was
pre-heated by partially submerging it in the molten metal for
several minutes. The mold was then completely submerged to allow it
to fill with molten metal. Alternatively, the mold may be inserted
into a furnace, such as a vertical tube furnace, to pre-heat the
mold and then filled by ladling the molten metal into the mold from
a separate melting furnace.
[0015] After filling the mold with molten metal, the mold was
shaken and turned to make sure the tapes were wetted by the molten
metal. While the shaking step was included for these examples, it
is not necessary to provide a cast structure with MMC
reinforcements. FIG. 3 is an illustration of one of the finished
castings. The finished casting 20 included the MMC tapes 16 within
a cast aluminum body 22. The samples were tested to determine the
effect on flexural strength and the results are shown in FIG. 4.
Castings reinforced with non-planar MMC tapes showed significant
improvement in load compared to unreinforced aluminum and
reinforced aluminum with planar MMC tape orientation.
[0016] While these samples consisted of tape with pure aluminum and
Nextel 610 fibers and casting metal of pure aluminum, MMC tape with
other alloys and other fiber types could be used. Similarly, other
alloys could be used for the casting metal. For example, castings
were also made by incorporating tape into 2014 aluminum alloy
castings. In addition, other methods of holding the tapes in
position could be utilized in order to achieve the same
results.
[0017] While the invention has been described in detail with
respect to certain preferred embodiments, the invention is limited
only be the appended claims.
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