U.S. patent application number 14/271819 was filed with the patent office on 2014-11-13 for wear-resistant alloys having complex microstructure.
This patent application is currently assigned to Hyundai Motor Company. The applicant listed for this patent is Hyundai Motor Company. Invention is credited to Hee Sam Kang.
Application Number | 20140334973 14/271819 |
Document ID | / |
Family ID | 51787744 |
Filed Date | 2014-11-13 |
United States Patent
Application |
20140334973 |
Kind Code |
A1 |
Kang; Hee Sam |
November 13, 2014 |
WEAR-RESISTANT ALLOYS HAVING COMPLEX MICROSTRUCTURE
Abstract
A wear-resistant alloy is provided that has a complex
microstructure. from the microstructure includes a range of about 8
to about 17 wt % of zinc (Zn), a range of about 5 to about 8 wt %
of tin (Sn), a range of about 1.0 to about 2.0 wt % of iron (Fe),
and a balance of aluminum (Al).
Inventors: |
Kang; Hee Sam; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hyundai Motor Company |
Seoul |
|
KR |
|
|
Assignee: |
Hyundai Motor Company
Seoul
KR
|
Family ID: |
51787744 |
Appl. No.: |
14/271819 |
Filed: |
May 7, 2014 |
Current U.S.
Class: |
420/530 ;
420/540; 420/541 |
Current CPC
Class: |
C22C 21/003 20130101;
C22C 21/10 20130101 |
Class at
Publication: |
420/530 ;
420/540; 420/541 |
International
Class: |
C22C 21/10 20060101
C22C021/10; C22C 21/00 20060101 C22C021/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2013 |
KR |
10-2013-0051293 |
Claims
1. A wear-resistant alloy having a complex microstructure,
comprising: a range of about 8 to about 17 wt % of zinc (Zn); a
range of about 5 to about 8 wt % of tin (Sn); a range of about 1.0
to about 2.0 wt % of iron (Fe); and a balance of aluminum (Al).
2. The wear-resistant alloy of claim 1, further comprising: a range
of about 1 to about 3 wt % of copper (Cu).
3. The wear-resistant alloy of claim 1, further comprising: a range
of about 0.3 to about 0.8 wt % of magnesium (Mg).
4. The wear-resistant alloy of claim 1, further comprising: a range
of about 1 to about 3 wt % of copper (Cu) and from about 0.3 to
about 0.8 wt % of magnesium (Mg).
5. A wear-resistant alloy having a complex microstructure,
comprising: a range of about 8 to about 17 wt % of zinc (Zn); a
range of about 5 to about 8 wt % of bismuth (Bi); a range of about
1.0 to about 2.0 wt % of iron (Fe); and a balance of aluminum (Al).
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority of Korean Patent
Application Number 10-2013-0051293 filed on May 7, 2013, the entire
contents of which application are incorporated herein for all
purposes by this reference.
TECHNICAL FIELD
[0002] The present invention relates to an aluminum alloy used for
vehicle parts which may require wear resistance and self-lubricity,
and a method of preparing the aluminum alloy. In particular, the
present invention provides an aluminum alloy having a complex
microstructure, which may include wear-resistant particles and
self-lubricating soft particles.
BACKGROUND
[0003] As an aluminum alloy, a hypereutectic aluminum-iron (Al-Fe)
alloy containing from about 13.5 to 18 wt %, or about 12 wt %, of
silicon (Si), and from about 2 to about 4 wt % of copper (Cu) has
been generally used in a vehicle industry. Since such conventional
hypereutectic Al-Fe alloy has a microstructure with primary silicon
(Si) particles having a size of from about 30 to about 50 .mu.m, it
may have improved wear resistance compared to mere Al-Fe alloys,
and thus it may be generally used for vehicle parts which may
require wear resistance, such as a shift fork, rear cover, swash
plate, and the like. An example of commercial alloys may include: a
R14 alloy (manufactured by Ryobi Corporation, Japan), a K14 alloy
which is similar to the R14 alloy, an A390 alloy which is used for
a monoblock or aluminum liner, and the like.
[0004] However, such hypereutectic alloys may have problems due to
high silicon content, such as, low castability, low impact
resistance, and the like. In addition, adjustment of size and
distribution of silicon (Si) particles may be difficult, and
manufacturing hypereutectic alloys may cost more than other
aluminum alloys because of specifically developed process.
[0005] Meanwhile, an An-Sn alloy may be another example of
self-lubricating aluminum alloy for vehicle parts. The An-Sn alloy
may include from about 8 to about 15 wt % of tin (Sn), and further
include microstructure of self-lubricating tin (Sn) soft particles,
which may reduce friction. Therefore, such An-Sn alloy may be used
as a base material of metal bearings used in high frictional
contact interfaces. However, this An-Sn alloy may not be suitable
for structural vehicle parts due to low strength, for instance,
about 150 MPa or less, although the strength may be reinforced by
silicon (Si) content.
[0006] The description provided above as a related art of the
present invention is just merely for helping understanding the
background of the present invention and should not be construed as
being included in the related art known by those skilled in the
art.
SUMMARY OF THE INVENTION
[0007] The present invention may provide a technical solution to
the above-mentioned problems. Therefore, in one aspect, the present
invention provides a novel high-strength and wear-resistant alloy
having a microstructure which may be obtained from both hard
particles and soft particles thereof. In particular, the novel
alloy may have wear resistance from a hypereutectic Al-Fe and
self-lubricity from an Al-Sn alloy.
[0008] In one exemplary embodiment, the present invention provides
a wear-resistant alloy having a complex microstructure which may
include: from about 8 to about 17 wt % of zinc (Zn); from about 5
to about 8 wt % of tin (Sn); from about 1.0 to about 2.0 wt % of
iron (Fe); and a balance of aluminum (Al). The wear-resistant alloy
may further include from about 1 to about 3 wt % of copper (Cu).
The wear-resistant alloy may also include from about 0.3 to about
0.8 wt % of magnesium (Mg). In addition, the wear-resistant alloy
may include from about 1 to about 3 wt % of copper (Cu) and from
about 0.3 to about 0.8 wt % of magnesium (Mg).
[0009] In another exemplary embodiment, the present invention
provides a wear-resistant alloy having a complex microstructure
which may include: from about 8 to about 17 wt % of zinc (Zn); from
about 5 to about 8 wt % of bismuth (Bi); from about 1.0 to about
2.0 wt % of iron (Fe); and a balance of aluminum (Al).
BRIEF DESCRIPTION OF THE DRAWING
[0010] The above and other features of the present invention will
now be described in detail with reference to certain exemplary
embodiments thereof illustrated the accompanying drawings which are
given hereinbelow by way of illustration only, and thus are not
limitative of the present invention, and wherein:
[0011] FIG. 1 is an exemplary graph showing a correlation between
friction efficient and tin (Sn) content in wt % or zinc (Zn)
content in wt % of wear-resistant alloys having a complex
microstructure according to an exemplary embodiment of Examples and
Comparative Examples with respect to soft particles.
DETAILED DESCRIPTION
[0012] It is understood that the term "vehicle" or "vehicular" or
other similar term as used herein is inclusive of motor vehicles in
general such as passenger automobiles including sports utility
vehicles (SUV), buses, trucks, various commercial vehicles,
watercraft including a variety of boats and ships, aircraft, and
the like, and includes hybrid vehicles, electric vehicles, plug-in
hybrid electric vehicles, hydrogen-powered vehicles and other
alternative fuel vehicles (e.g. fuels derived from resources other
than petroleum). As referred to herein, a hybrid vehicle is a
vehicle that has two or more sources of power, for example both
gasoline-powered and electric-powered vehicles.
[0013] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. As
used herein, the term "and/or" includes any and all combinations of
one or more of the associated listed items.
[0014] Unless specifically stated or obvious from context, as used
herein, the term "about" is understood as within a range of normal
tolerance in the art, for example within 2 standard deviations of
the mean. "About" can be understood as within 10%, 9%, 8%, 7%, 6%,
5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated
value. Unless otherwise clear from the context, all numerical
values provided herein are modified by the term "about".
[0015] Hereinafter, various exemplary embodiments of the present
invention will be described in detail. The present invention
relates to a novel alloy having a complex microstructure, which may
include both hard particles and soft particles
[0016] In certain examples of conventional aluminum alloys, alloy
elements for forming self-lubricating particles may include tin
(Sn), lead (Pb), bismuth (Bi), zinc (Zn) and the like. These alloy
elements may not be formed into intermetallic compounds because
they may not react with aluminum, and the phase thereof may be
separated. Further, these alloy elements may have relatively low
melting points and have self-lubricity for forming a lubricating
film while partially melting under a severe friction condition.
[0017] Among the above-mentioned four alloy elements, lead (Pb) may
be the most suitable element for forming self-lubricating particles
when considering both self-lubricity and cost. However, lead is
prohibited in vehicles because it is classified as a harmful metal
element. In this regard, tin (Sn) may be the most widely used
element instead of Pb, and bismuth (Bi) may be used occasionally
instead of Sn. In contrast, zinc (Zn) may be disadvantageous due to
a substantially high melting point compared to Sn and Bi, and
substantially low self-lubricity. However, Zn may be added in
relatively substantial amount, due to low cost. Therefore, in
consideration of cost competitiveness, Zn may be used for forming
soft particles and partially replacing expensive Sn or Bi.
[0018] Further, Si or Fe may be an alloy element for forming hard
particles. Si or Fe may cause an eutectic reaction together with
Al, and form angular hard particles when added in a predetermined
amount or greater. In an example of aluminum alloys, Si may form
hard particles, and may form primary silicon particles. Si may
provide wear resistance when it is added to a binary Al-Fe alloy in
an amount of about 12.6 wt % or greater. However, when Si is added
together with Zn which is an element for forming soft particles, Si
content may be changed according to the Zn content to form hard
particles. For example, Si content may be from about 7 wt % at
minimum to about 14 wt % at maximum, when the Zn content is about
10 wt %. When the Si content is less than about 7 wt % at minimum,
hard particles may not be formed,; and when the Si content is
greater than 14 wt % at maximum, the size of hard particles may
significantly increase, thereby creating a negative influence on
mechanical properties and wear resistance.
[0019] In Al-Fe alloys, Fe may be an impurity. However, when an
Al-Fe binary alloy contains no Si and Fe is added in an amount of
about 0.5 wt % or less, wear-resistant Al-Fe intermetallic compound
particles may be formed, thereby providing wear resistance to the
Al-Fe alloy. In contrast, when Fe is added in an amount of about 3
wt % or greater, the intermetallic compound particles may be
excessively formed, thereby deteriorating mechanical properties and
increasing the melting point.
[0020] Furthermore, alloy elements for reinforcing the strength of
an exemplary aluminum alloy may include Cu and Mg. Cu may be
effective in forming intermetallic compounds and increasing
strength through a chemical reaction with Al. The effect of Cu may
vary depending on the Cu content, casting/cooling conditions or
heat-treatment conditions. In addition, Mg may be effective in
forming intermetallic compounds and increasing strength through a
chemical reaction with Si or Zn. The effect of Mg may also vary
depending on the Mg content, casting/cooling conditions or
heat-treatment conditions.
[0021] Hereinafter, the present invention will be described in
detailed exemplary embodiments.
[0022] In one exemplary embodiment, the aluminum alloy may include
aluminum (Al) as a main component, and further include from about 8
to about 17 wt % of zinc (Zn); from about 5 to about 8 wt % of tin
(Sn); from about 1 to about 3 wt % of copper (Cu); from about 0.3
to about 0.8 wt % of magnesium (Mg); and from about 1.0 to about
2.0 wt % of iron (Fe) for forming hard particles. When zinc (Zn) is
added in an amount of less than 8 wt %, a sufficient amount of Zn
soft particles may not be formed, and thus it may be difficult to
obtain sufficient self-lubricity. When zinc (Zn) is added in an
amount greater than about 17 wt %, the liquidus line of the
aluminum alloy may be lowered substantially, and thereby
deteriorating casting conditions.
[0023] Additionally, tin (Sn) may have greater self-lubricity than
zinc (Zn). When tin (Sn) is added in an amount of less than 5 wt %,
a sufficient amount of Sn soft particles may not be formed, and
thus it may be difficult to compensate for insufficient
self-lubricity of Zn soft particles. When tin (Sn) is added in an
amount of greater than 8 wt %, the melting point of the aluminum
alloy may become significantly low, and thus such aluminum alloy
may not be used as a commercial material.
[0024] Ion (Fe) may form hard particles. When iron (Fe) is added in
an amount of less than about 1.0 wt %, Al-Fe intermetallic compound
soft particles may not be sufficiently formed, for instance, less
than about 0.5 wt %,, and thus it may be difficult to ensure wear
resistance. When iron (Fe) is added in an amount of greater than
about 2.0 wt %, the Al-Fe intermetallic compound soft particles may
be excessively formed, for instance, greater than about 5 wt %, and
thus these soft particles may be coarsened, thereby creating a
negative influence on wear resistance and mechanical
properties.
[0025] Copper (Cu) may improve mechanical properties and copper
(Cu) may be added in an amount of about 1 wt % or greater to ensure
sufficient mechanical properties. However, when copper (Cu) is
added in an amount of greater than about 3 wt %, other elements and
intermetallic compounds may be formed to deteriorate the mechanical
properties of the aluminum alloy. Thus, the amount of copper (Cu)
may be limited. Alternatively, magnesium (Mg), may be added instead
of Copper (Cu) in an amount of about 0.3 wt % or greater, and the
mechanical properties of the aluminum alloy may be additionally
improved. However, when magnesium (Mg) is added in an amount
greater than about 0.8 wt %, compounds deteriorating the mechanical
properties of the aluminum alloy may be formed, and thus the amount
of Mg may be limited.
[0026] The low frictional characteristics of the Al-Zn-Sn alloy
according to an exemplary embodiment of the present invention have
been evaluated with respect to soft particles. As shown in FIG. 1,
exemplary alloys of Examples and Comparative Examples were prepared
while changing the amount of Zn and Sn, and then the changes in
friction coefficients of the alloys were measured. As a result,
under a condition of about 5 wt % Sn, an exemplary 5Sn-9Zn alloy of
Example may obtain desired low frictional characteristics, for
instance, friction coefficient of about 0.150 or less; and an
exemplary 5Sn-5Zn and 5Sn-7Zn alloys of Comparative Examples may
obtain undesired results. Therefore, when Zn is added in an amount
of about 8 wt % or greater whereas Sn is added of about 5 wt % or
greater, desired low frictional characteristics may be obtained. In
addition, even when the amount of Sn and Zn increases, satisfactory
low frictional characteristics may be obtained.
[0027] The results of evaluation of wear resistance and mechanical
properties of exemplary Al-Zn-Sn alloys of Examples and Comparative
Examples are given in Table 1 below.
TABLE-US-00001 TABLE 1 Al--Fe particle Al Zn Sn Fe Cu Mg fraction
Liquidus Strength Class. (wt %) (wt %) (wt %) (wt %) (wt %) (wt %)
(%) line (.degree. C.) (MPa) Comp. residue 15 5 0.6 2 0.5 0 -- --
Examples residue 15 5 0.8 2 0.5 0.2 -- -- Examples residue 15 5 1.0
2 0.5 0.5 -- 370 residue 15 5 1.8 2 0.5 4.0 710 295 residue 15 5
2.0 2 0.5 5.0 720 305 Comp. residue 15 5 2.2 2 0.5 5.2 730 --
Example
[0028] In Table 1, exemplary Al-15Zn-5Sn-yFe alloys of Comparative
Examples, which may include about 0.8 wt % of Fe, Al-Fe particles
in forms of soft particles may be formed in minimal amounts, for
instance, less than about 0.5 wt %, therefore insufficient wear
resistance may be obtained. In contrast, when Fe is included in an
excessive amount of about 2.2 wt %, Al-Fe particles as of soft
particles may be formed in excess amounts, for instance, greater
than about 5 wt %, and thus opposite effects may occur due to the
coarsening of intermetallic compounds. Moreover, in another
exemplary embodiment, Al-15Zn-5Sn-yFe alloys of Examples, which may
include from about 1.0 to about 2.0 wt % of Fe, Al-Fe particles
(soft particles) may be formed in suitable amounts (e.g.,
predetermined amounts), and the strengths thereof may be from about
295 to about 370 MPa, and thus both wear resistance and mechanical
properties may be improved.
[0029] The aluminum alloy according to another exemplary embodiment
of the present invention may include: from about 8 to about 17 wt %
of zinc (Zn); from about 5 to about 8 wt % of bismuth (Bi); from
about 1.0 to about 2.0 wt % of iron (Fe); a balance of aluminum
(Al). In particular, bismuth (Bi) may be used as a strong
self-lubricating material instead of tin (Sn).
[0030] As described above, the wear-resistant alloy having a
complex microstructure according to exemplary embodiments of the
present invention may have both wear resistance as of a
hypereutectic Al-Fe alloy and self-lubricity as of an Al-Sn alloy,
thereby achieving high strength and improved wear resistance.
[0031] Although the exemplary embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *