U.S. patent application number 14/270628 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 | 20140334969 14/270628 |
Document ID | / |
Family ID | 51787753 |
Filed Date | 2014-11-13 |
United States Patent
Application |
20140334969 |
Kind Code |
A1 |
Kang; Hee Sam |
November 13, 2014 |
WEAR-RESISTANT ALLOYS HAVING COMPLEX MICROSTRUCTURE
Abstract
A wear-resistant alloy having a complex microstructure is
provided. from the microstructure includes a range of about 19 to
about 27 wt % of zinc (Zn), a range of about 3 to about 5 wt % of
tin (Sn), a range of about 7.6 to about 11 wt % of silicon (Si),
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: |
51787753 |
Appl. No.: |
14/270628 |
Filed: |
May 6, 2014 |
Current U.S.
Class: |
420/530 ;
420/540; 420/541 |
Current CPC
Class: |
C22C 21/10 20130101 |
Class at
Publication: |
420/530 ;
420/540; 420/541 |
International
Class: |
C22C 21/10 20060101
C22C021/10 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2013 |
KR |
10-2013-0051291 |
Claims
1. A wear-resistant alloy having a complex microstructure,
comprising: a range of about 19 to about 27 wt % of zinc (Zn); a
range of about 3 to about 5 wt % of tin (Sn); a range of about 7.6
to about 11 wt % of silicon (Si); 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 19 to about 27 wt % of zinc (Zn); a
range of about 3 to about 5 wt % of bismuth (Bi); a range of about
7.6 to about 11 wt % of silicon (Si); and a balance of aluminum
(Al).
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority of Korean Patent
Application Number 10-2013-0051291 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 a range of about 13.5 to about 18 wt %, or about
12 wt %, of silicon (Si) and a range of about 2 to about 4 wt % of
copper (Cu) has been generally used in a vehicle industry. Since
such conventional Al--Fe alloy has a microstructure with primary
silicon (Si) particles having a size of a range of 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.
[0004] An example of commercial alloys may include: an 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.
[0005] 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 due to specifically developed process.
[0006] Meanwhile, an An-Sn alloy may be another example of
self-lubricating aluminum alloy for vehicle parts. The An-Sn alloy
may include a range of 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 a substantially low
strength of about 150 MPa or less, although the strength may be
reinforced by silicon (Si) content.
[0007] 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
[0008] 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 both wear resistance from a hypereutectic Al--Si and
self-lubricity from an Al--Sn alloy.
[0009] In one exemplary embodiment of the present invention
provides a wear-resistant alloy having a complex microstructure,
which may include: a range of about 19 to about 27 wt % of zinc
(Zn); a range of about 3 to about 5 wt % of tin (Sn); a range of
about 7.6 to about 11 wt % of silicon (Si); 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).
[0010] In another exemplary embodiment, the present invention
provides a wear-resistant alloy having a complex microstructure,
which may include: a range of about 19 to about 27 wt % of zinc
(Zn); a range of about 3 to about 5 wt % of bismuth (Bi); a range
of about 7.6 to about 11 wt % of silicon (Si); and a balance of
aluminum (Al).
BRIEF DESCRIPTION OF THE DRAWING
[0011] The above and other objects, features and advantages of the
present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawing, in which:
[0012] 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
[0013] 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.
[0014] 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.
[0015] 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".
[0016] 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.
[0017] 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.
[0018] Among the above-mentioned four alloy elements, lead (Pb) may
be is the most suitable element for forming self-lubricating
particles when considering both self-lubricity and cost. However,
lead is prohibited in a vehicle industry because it is classified
as a harmful metal element. In this regard, tin (Sn) may be most
widely used 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, zinc
may be 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.
[0019] In addition, 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 it is added in a
predetermined amount or more. In an example of aluminum alloys, Si
may be form hard particles, and form primary silicon particles.
Further, Si may provide wear resistance when it is added to a
binary Al--Si 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 Zn
content to form hard particles. For example, Si content may be
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 7 wt %
at minimum, hard particles may not be formed; and, when the Si
content is greater than about 14 wt % at maximum, the size of hard
particles may significantly increase, thereby creating a negative
influence on mechanical properties and wear resistance.
[0020] In Al--Fe alloys, Fe may be an impurity. However, when an
Al--Fe binary alloy contains no (e.g., minimal) 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.
[0021] 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 of Cu with Al. The effect of
Cu may vary depending on the Cu content, casting/cooling conditions
or heat-treatment conditions. Mg may be effective in forming
intermetallic compounds and increasing strength through a chemical
reaction of Mg with Si or Zn. The effect of Mg may also vat
depending on the Mg content, casting/cooling conditions or
heat-treatment conditions.
[0022] Hereinafter, the present invention will be described in
detailed exemplary embodiments.
[0023] In one exemplary embodiment, the aluminum alloy may include
aluminum (Al) as a main component, and further includes a range of
about 19 to about 27 wt % of zinc (Zn); a range of about 3 to about
5 wt % of tin (Sn); a range of about 1 to about 3 wt % of copper
(Cu); a range of about 0.3 to about 0.8 wt % of magnesium (Mg); and
a range of about 7.6 to about 11 wt % of silicon (Si) for forming
hard particles. When zinc (Zn), is added in an amount of less than
about 19 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 of greater
than about 27 wt %, the solidius line of the aluminum alloy may
become substantially low, and thereby deteriorating casting
conditions.
[0024] Further, tin (Sn) may have greater self-lubricity than zinc
(Zn). When tin (Sn) is added in an amount of less than about 3 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 about 5 wt %, the friction reducing effect
of the aluminum alloy may not be obtained under a driving
condition, the thus amount of Sn may be minimized in terms of
efficiency.
[0025] Silicon (Si) may form hard particles. When silicon (Si) is
added in an amount of less than about 7.6 wt %, primary Si hard
particles may not be formed sufficiently, for instance, less than
about 0.5 wt %, and it may be difficult to ensure wear resistance.
When silicon (Si) is added in an amount of greater than about 11 wt
%, the primary Si hard particles may be excessively formed, for
instance, greater than about 5 wt %, thereby coarsening hard
particles and creating a negative influence on wear resistance and
mechanical properties.
[0026] 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, and thus the amount of copper
(Cu) may be limited. Alternatively, magnesium (Mg), instead of
Copper (Cu), may be added 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 of about 0.8 wt % or greater, compounds deteriorating the
mechanical properties of the aluminum alloy may be formed, and thus
the amount of magnesium (Mg) may be limited.
[0027] 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 3 wt % Sn, exemplary 3Sn-19Zn alloys of
Examples may obtain desired low frictional characteristics, for
instance, friction coefficient of about 0.150 or less, and
exemplary 3Sn-17Zn alloys of Comparative Examples may obtain
undesired results. Therefore, when Zn is added in an amount of
about 19 wt % or greater based on about 3 wt % or greater of Sn,
desired low frictional characteristics may be obtained. In
addition, when the amounts of Sn and Zn increases, satisfactory low
frictional characteristics may be obtained. The results of
evaluation of wear resistance and mechanical properties of
exemplary Al-25Zn-3Sn-xSi alloys of Examples and Comparative
Examples are given in Table 1 below.
TABLE-US-00001 TABLE 1 Zn Sn Si Cu Mg Si particle Strength Class.
Al (wt %) (wt %) (wt %) (wt %) (wt %) fraction (%) (MPa) Comp.
residue 25 4 7 2 0.5 0 -- Examples residue 25 4 7.4 2 0.5 0.3 --
Examples residue 25 4 7.6 2 0.5 0.5 335 residue 25 4 8.4 2 0.5 2 --
residue 25 4 11 2 0.5 5 345 Comp. residue 25 4 11.2 2 0.5 5.2 --
Example
[0028] In Table 1 above, when exemplary Al-25Zn-3Sn-xSi alloys of
Comparative Examples which may include a range of about 7.6 to
about 11 wt % of Si, Si hard particles may be formed in a maximum
amount of about 5 wt %, thereby obtaining sufficient wear
resistance. In contrast, when Si is included in an amount of about
11.2 wt %, primary Si particles may be formed in an amount of
greater than about 5 wt %, and Si particles may be coarsened and
segregated, and thus the amount thereof may be limited.
[0029] Meanwhile, the strengths of exemplary Al-25Zn-35Sn-xSi
alloys may be a range of about 335 to about 345 MPa regardless of
the amount of Si, and thus these alloys may be used as structural
materials for vehicle parts. The aluminum alloy according to
another exemplary embodiment of the present invention may include:
a range of about 19 to about 27 wt % of zinc (Zn); a range of about
3 to about 5 wt % of bismuth (Bi); a range of about 7.6 to about 11
wt % of silicon (Si); and 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 the wear resistance from a
hypereutectic Al--Si alloy and the self-lubricity from an Al--Sn
alloy, thereby achieving high strength and excellent 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.
* * * * *