Note: Descriptions are shown in the official language in which they were submitted.
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BRASS ALLOY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to copper alloys, and more particularly, to an
environment friendly brass alloy.
2. Description of Related Art
A brass includes copper and zinc, as major ingredients, usually in a ratio of
about
7:3 or 6:4. In addition, a brass usually includes a small amount of
impurities. In order
to improve the properties of a brass, a conventional brass contains lead
(mostly in the
range of 1 to 3 wt%) to achieve the desired mechanical properties for use in
the
industry, thereby becoming an important industrial material that is widely
applicable to
metallic devices and valves for use in pipelines, faucets and water supply and
discharge
systems.
However, as awareness of the importance of environmental protection increases
and the impact of heavy metals on human health becomes better understood, it
is a
trend to restrict the use of lead-containing alloys. Various countries, such
as Japan and
the United States, have progressively amended relevant regulations in an
intensive
effort to lower the lead content in the environment by particularly requiring
that no lead
shall leach from lead-containing alloys used in products ranging from
household
appliances and automobiles to residential water pipes and municipal water
systems,
while also requiring that lead contamination shall be avoided during
processing. Hence,
there is a need to develop lead-free brass with good properties for casting,
cutting,
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corrosion-resisting and mechanical processing.
Currently, there are many formulations of lead-free copper alloy. For example,
Taiwanese Patent No. 421674, US Patent No. 7354489, and US Patent Application
Publication
Nos. 20070062615, 20060078458 and 2004023441 disclose adding silicon (Si) in a
brass alloy
instead of lead. However, the alloys made from these formulations have poor
property for
cutting. In addition, Chinese Patent Application Publication No. 10144045
discloses
aluminum, silicon and phosphorous as main components of a lead-free copper
alloy. This lead-
free copper alloy can be used for casting, but has poor property for cutting
and much lower
processing efficiency than lead-containing brass. Chinese Patent Application
Publication Nos.
101285138 and 101285137 disclose phosphorous as main component in an alloy;
however,
cracks are easily formed while casting this alloy.
In addition, US Patent Nos. 7,297,215, 6,974,509, 6,955,378, 6,149,739,
5,942,056,
5,637,160, 5,653,827, 5,487,867 and 5,330,712, and US Patent Application
Publication Nos.
20060005901, 20040094243 and 20070039667, disclose lead-free or low-lead
bismuth-
containing brass alloy formulations, wherein the bismuth content of the
formulations ranges
from 0.5 wt% to 7 wt%. Further, US Patent No. 6413330 discloses a lead-free
copper alloy
containing bismuth, silicon and other components. Chinese Patent Application
Publication No.
101440444 also discloses a lead-free brass alloy having high content of zinc
and silicon, but
this brass alloy has high content of silicon and low content of copper, such
that the fluidity of
the melt alloy is poor to fill the cavity while casting, resulting in
disadvantages such as misnm,
etc. Chinese Patent Application Publication No. 101403056 discloses bismuth
and manganese
in a lead-free brass alloy instead of lead. However, high bismuth content is
likely to cause
defects like cracks and slag inclusions, leading to low processing
efficiencies. On the
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other hand, low bismuth content and high manganese content cause less cracks,
but
have poor cutting property.
Due to rare resource and expensive cost, high bismuth content instead of lead
results in high fabrication cost of a lead-free brass. Further, the above-
mentioned
brass alloys have drawbacks such as poor casting property, easily forming
cracks,
etc.
Moreover, there are literatures disclosing the improvement of a fabrication of
a
lead-free copper alloy or a lead removal process. For example, US Patent No.
5904783 discloses treating a brass alloy with the sodium and potassium
solution at a
high temperature for reducing lead leaching into a fluid supply. Taiwanese
Patent No.
491897 discloses a method for fabricating a brass alloy having 1-2.6 wt% of
bismuth.
However, the conventional lead removal process is used for reducing lead,
which is in
contact with water, leaching when the lead-containing product is immersed in
water,
but fails to reduce the lead content to less than 0.3 wt% in a material.
SUMMARY OF THE INVENTION
The present invention provides an environmental friendly brass alloy.
The environmental friendly brass alloy includes 0.4 to 0.8 wt% of aluminum;
0.6 to 1.6 wt% of nickel; 0.8 to 2.0 wt% of tin; more than 95.6 wt% of copper
and zinc;
and less than 0.1 wt% of iron, lead, phosphorous and impurities, wherein the
copper
is in an amount ranging from 60 to 68 wt%.
According to an aspect of the invention, there is provided a brass alloy,
consisting of: 0.4 to 0.8 wt% of aluminum; 0.6 to 1.6 wt% of nickel; 0.8 to
2.0 wt% of
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tin; more than 95.6 wt% of copper and zinc, wherein the copper is present in
an
amount ranging from 60 to 68 wt%; and the remainder being iron, lead,
phosphorous
and impurities; and wherein the lead is present in an amount ranging from 0.05
to
0.003 wt%.
In the environmental friendly brass alloy of the present invention, the copper
and zinc are present in an amount more than 95.6 wt%. In an aspect, the copper
is
present in an amount ranging from 60 to 68 wt% of the environmental friendly
brass
alloy, so as to provide toughness and to facilitate subsequent processes. In a
preferred embodiment, the copper is in an amount ranging from 61 to 64 wt%.
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In the environmental friendly brass alloy of the present invention, the
aluminum is
present in an amount ranging from 0.4 to 0.8 wt%. In a preferred embodiment,
the
aluminum is present in an amount ranging from 0.5 to 0.6 wt%, in which the
addition
of aluminum increases the fluidity of melt copper and improves casting
property of the
brass alloy.
In the environmental friendly brass alloy of the present invention, the nickel
is
present in an amount ranging from 0.6 to 1.6 wt%. In a preferred embodiment,
the
nickel is present in an amount ranging from 0.8 to 1.4 wt%, in which the
addition of
nickel improves the mechanical property and corrosion-resistance of the brass
alloy.
In the environmental friendly brass alloy of the present invention, the tin is
present
in an amount ranging from 0.8 to 2.0 wt%. In a preferred embodiment, the tin
is
present in an amount ranging from 1.2 to 1.6 wt%, in which the addition of tin
increases the corrosion-resistance of the brass alloy to the environment with
high
chloride (such as sea water) and increases the strength of the brass alloy.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG 1A shows a metallographic structural distribution of a specimen of an
environmental friendly brass alloy according to the present invention;
FIG 1B shows a metallographic structural distribution of a specimen of a lead-
free
bismuth brass alloy;
FIG. 1C shows a metallographic structural distribution of a specimen of an
C85710
lead brass;
FIG. 2A shows a crack of a lead-free bismuth brass alloy;
FIG 2B shows a microscopic image of the cracks of the lead-free bismuth brass
alloy;
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FIG 3A shows cuttings of a lead-free bismuth brass alloy;
FIG 3B shows cuttings of an C85710 lead brass; and
FIG 3C shows cuttings of the environmental friendly brass alloy according to
the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The detailed description of the present invention is illustrated by the
following
specific examples. Persons skilled in the art can conceive the other
advantages and
effects of the present invention based on the disclosure contained in the
specification of
the present invention.
Unless otherwise specified, the ingredients comprised in the environmental
friendly brass alloy of the present invention, as discussed herein, are all
based on the
total weight of the brass alloy, and are expressed in weight percentages
(wt%).
The environmental friendly brass alloy according to the present invention has
the
lead content less than 0.05 wt%, to comply with the international standards
for lead
content in pipeline materials in contact with water. Therefore, the
environmental
friendly brass alloy of the present invention is suitable for applications to
faucets and
lavatory components, pipelines for tap water, water supply systems, etc.
The environmental friendly brass alloy of the present invention includes 0.4
to 0.8
wt% of aluminum; 0.6 to 1.6 wt% of nickel; 0.8 to 2.0 wt% of tin; more than
95.6 wt%
of copper and zinc; and less than 0.1 wt% of iron, lead, phosphorous and
impurities,
wherein the copper is present in an amount ranging from 60 to 68 wt%.
In the environmental friendly brass alloy of the present invention, the copper
and
zinc are present in an amount more than 95.6 wt%, wherein the copper is
present in an
amount ranging from 60 to 68 wt% of the environmental friendly brass alloy.
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Preferably, the copper is in an amount ranging from 61 to 64 wt%.
In the environmental friendly brass alloy of the present invention, the
aluminum is
present in an amount ranging from 0.4 to 0.8 wt%. In a preferred embodiment,
the
aluminum is present in an amount ranging from 0.5 to 0.6 wt%. The addition of
aluminum increases the fluidity of melt copper and improves casting property
of the
brass alloy. Further, in the environmental friendly brass alloy of the present
invention,
the nickel is present in an amount ranging from 0.6 to 1.6 wt%. In a preferred
embodiment, the nickel is present in an amount ranging from 0.8 to 1.4 wt%.
The
addition of nickel improves the mechanical property, corrosion-resistance and
dezincification-resistance of the brass alloy. In the environmental friendly
brass alloy
of the present invention, the tin is present in an amount ranging from 0.8 to
2.0 wt%. In
a preferred embodiment, the tin is present in an amount ranging from 1.2 to
1.6 wt%.
The addition of tin increases the corrosion-resistance of the brass alloy to
the
enviromnent with high chloride (such as sea water) and increases the strength
of the
brass alloy.
The present invention provides the detailed illustrations in the following
examples.
The ingredients of the environmental brass alloy of the present invention used
in the
following test examples are described as follows, wherein each ingredient is
added at a
proportion based on the total weight of the brass alloy.
Example 1 of the environmental friendly brass alloy:
Cu: 61.37 wt% Ni: 0.815 wt%
Al: 0.537 wt% Sn: 1.246 wt%
Pb: 0.0103 wt%
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Zn, trace elements and impurities: in balance
Example 2 of the environmental friendly brass alloy:
Cu: 62.45 wt% Ni: 0.989 wt%
Al: 0.578 wt% Sn: 1.423 wt%
Pb: 0.078 wt%
Zn, trace elements and impurities: in balance
Example 3 of the environmental friendly brass alloy:
Cu: 63.34 wt% Ni: 1.167 wt%
Al: 0.564 wt% Sn: 1.548 wt%
Pb: 0.0036 wt%
Zn, trace elements and impurities: in balance
Test Example 1:
The environmental friendly brass alloy (Embodiments 1-3), lead-free bismuth
brass
(Comparative examples 1-3) and C85710 lead brass (Comparative examples 4-5)
are
used for casting under the same process and operation condition. The
processing
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characteristics and yields of these brass alloys are shown in Table 1. The
overall
production yield was calculated by the following equation:
0. P. Yield = Number of Non-Defective Products/Total Number of Products x 100%
The overall production yield (0. P. Yield) reflects the qualitative stability
of
production processes. High qualitative stability of production processes
ensures normal
production.
Table 1
Environmental friendly brass alloy of
Lead-free bismuth brass C85710 lead brass
the present invention
Item
ComparativeComparative Comparative Comparative Comparative Embodiment
Embodiment Embodiment
example 1 example 2 example 3 example 4 example 5 1 2 3
Measured Cu
content 61.92 62.57 63.01 62.3 61.5 61.37 62.45
63.64
(wt%)
Measured Al
content 0.541 0.581 0.513 0.548 0.554 0.537
0.578 0.564
(wt%)
Measured Pb
content 0.0016 0.0073 0.0054 1.89 1.67 0.0103
0.0078 0.0036
(wt%)
Measured Ni
content 0.263 0.449 0.851 0.0076 0.0042 0.815
0.989 1.167
(wt%)
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Measured Sn
content 0.0054 0.0008 0.0023 0.0007 0.0005
1.246 1.423 1.548
(wt%)
Number of
1000 1000 WOO 1000 1000 1000 1000 1000
total products
Number of
non-defective 583 612 679 891 885 856 873 882
products
Yield 58.3% 61.2% 67.9% 89.1% 88.5% 85.6%
87.3% 88.2%
As shown in Table 1, the products made of the lead-free bismuth brass alloy
have
more defects, and have the yield less than 70%, wherein more bismuth content
results
in the fewer yield. The casting product of the lead-free bismuth brass has the
drawbacks such pores, cracks, slag entrapment, misrun and loose.
Specifically, the melt
copper of the lead-free bismuth brass has poor fluidity and poor filling in a
mold,
resulting in the misrun. Further, the casting products easily form crack,
which are
usually found while polishing. Moreover, the casting products easily form slag
entrapment and pores.
As shown in Table 1, the products made from the environmental friendly
brass
alloy in the present invention had the best yield (more than 85%), and had the
fluidity
close to the conventional C85710 lead brass. Further, upon optimization of the
casting
products, the casting product formed the isometric crystal structures after
solidification,
so as to eliminate the formation of cracks and to meet the requirement of
production.
Test Example 2:
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It is shown in FIGS. IA, 1B and IC that the structural distributions of the
environmental friendly brass alloy of the present invention, the lead-free
bismuth brass
and C85710 lead brass were examined under an optical metallographic microscope
at
100X magnification.
In Embodiment 3 of the present invention, the environmental friendly brass
alloy
included 63.64 wt% of Cu, 0.564 wt% of Al, 0.0036 wt% of Pb, 1.167 wt% of Ni
and
1.548 wt% of Sn, and has the structural distribution as shown in FIG. IA. As
shown in
FIG. LA, smaller grains were formed so as to provide excellent material
toughness, and
thus defects like cracks were not likely to occur.
FIG. 1B shows the structural distribution of the lead-free bismuth brass in
Comparative example 3. In Comparative example 3, the lead-free bismuth brass
included 63.01 wt% of Cu, 0.513 wt% of Al, 0.0054 wt% of Pb, 0.851 wt% of Bi
and
0.0023 wt% of P. The high bismuth content caused more heterogeneous
nucleation,
quick nucleation and the increased a phase undercooling, resulting in more
dendritic
forms rather than blocks of grains. Therefore, the continuous pieces of
bismuth were
formed due to the grain boundary segregation, so as to make the mechanical
strength
decreased and to increase the hot shortness and cold shortness, such that
cracks were
easily formed.
FIG. 1C shows the structural distribution of the C85710 lead brass in
Comparative example 5. In Comparative example 5, the C85710 lead brass
included
61.5 wt% of Cu, 0.554 wt% of Al, 1.67 wt% of Pb, 0.0042 wt% of Bi and 0.0005
wt%
of P. The C85710 lead brass had the a phase of the globular grains and good
roughness, such that cracks were not likely to occur.
Upon casting, the lead-free high bismuth brass in Comparative example 1 had
the
crack as shown in FIG. 2A, and the image under the microscope was shown in
FIG.
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2B. The product made from the lead-free high bismuth brass was destroyed by
the
crack.
Test Example 3:
The tests on the mechanical properties of the brass alloys in Embodiment 3 and
Comparative example 5 were performed according to the standard set forth in
1S06998-1998, "Tensile experiments on metallic materials at room temperature."
The
results are shown in Table 2.
Table 2:
Mechanical properties
Material Tensile Strength (Mpa) Elongation (%)
1 2 3 4 5 Avg. 1 2 3 4 5 Avg.
Embodiment 3 424 411 438 417 424 422.8 12 11 11 11 10 11
Comparative
377 368 352 361 374 366.4 10 11 12 10 11 10.8
example 5
As shown in Table 2, the environmental friendly brass alloy in the present
invention had the tensile strength higher than the conventional C85710 lead
brass, and
had the elongation comparable to the conventional C85710 lead brass. Hence,
the
environmental friendly brass alloy in the present invention has the mechanical
properties comparable to the C85710 lead brass, and can indeed substitute for
the
C85710 lead brass in manufacturing of products.
Test Example 4:
The tests were performed according to the standard set forth in NSF 61-2007a
SPAC for the allowable precipitation amounts of metals in products, to examine
the
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amounts of the metal precipitations of the brass alloys in an aqueous
environment in
Embodiment 3 and Comparative example 5. The results are shown in Table 3.
Table 3
Comparative example
Upper Limit
Comparative 5
Element of Standard Embodiment 3
example 5 (after a lead- stripping
Value (14(L)
treatment)
Pb 5.0 14.452 0.561 0.364
Bi 50.0 0.026 0.015 0.017
Al 5.0 0.087 0.032 0.093
As shown in Table 3, the precipitation amounts of metals from the
environmental
friendly brass alloy in the present invention were all much lower than the
upper limit
of the standard values, so as to meet the requirement of NSF 61-2007a SPAC.
Moreover, the amounts of heavy metal precipitations from the environmental
friendly
brass alloy in the present invention were significantly lower than the C85710
lead
brass and significantly lower than the a lead-stripping treated C85710 lead
brass.
Hence, the brass alloy of the present invention is more environmentally
friendly and
has less risk to human health.
The environmental friendly brass alloy of the present invention has the
mechanical properties (such as cutting properties) comparable to the C85710
lead
brass, and even better properties (such as tensile strength) than the C85710
lead brass.
The casting products made from the environmental friendly brass alloy of the
present
invention have great yield, and also the yield of mechanical processing is
excellent.
Furthermore, the environmental friendly brass alloy of the present invention
reduces
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the amount of lead precipitations, and can substitute for the conventional
brass.
