Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Background of the Invention
The die casting industry has tried in the past to produce
strong parts using fiber- or particle-reinforced alloys. The
result was unsuccessful because of the difficulty of melt-flow,
i.e.,;fibers and particles do not flow intrinsically and hence
die cast parts show very rough surface texture, voids, cracks,
and restricted flow in thin sections. The irregular geometry of
particles or fibers with sharp edges, corners, and protrusions
induces poor melt-flowability by the mechanism of interlocking
and agglomeration. In other words, they are not die-castable
and thus parts with a smooth surface finish without defects cannot
be produced , for example, when the content of particles is
greater than about 5 ~ by volume. The breakthrough for this
problem has been achieved by the present invention, i.e., shot-
reinforced fusible, tin-based, lead-based, or zinc-based alloys.
Shots arè different from particles or fibers owing ta their
spherical shape and they intrinsically flow very well up to about
45 ~ by volume, producing a very smooth surface without voids in
die casting. Therefore, the mass production of die cast parts
which are strong and creep-resistant has become poss~ible with
shot-reinforced alloys.
Shots, in short, serve thw following pueposes.
(1) Strengthening
(2) Flowability
(3) Die-castability
Fibers or particles serve only the strengthening purpose with no
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flowability. In lost core technology, for instance, the inside
surface of intake manifolds must be smooth for the increase of
engine efficiency. When the plastic is molded around the fusible
core and subsequent decoring is done, the inside surface of the
plastic manifold is smooth only when the cast core surface is
smooth. Such smooth core having a desiable strength can be made
only with shot-reinforced alloys.
As a practical example, fusible alloys used in a fire
sprinkler system have a problem of cold flow under a stress due
to the weak strength of fusible alloys. In a prior art described
in U.S. Pat. No. 3,605,902, the reinforcement with random length
loose fibers has been suggested for strengthening fusible alloys.
This idea, howevçr, has not been successfully reduced to practice
because of the difficulty of economically forming an intermetallic
bonding between fibers and matrix alloy.
An extrusional flow of a fusible alloy under a high gas
pressure when it is used in a thermal plug of a valve or cylinder
has been a problem and a composite alloy comprised of conventional
fusible alloy reinforced with steel shots has been presented as a
solution in the patent-pending invention of U.S. File No.
07,290,743 filed Dec. 27, 1988.
The creep problem of zinc-based alloys has also been solved
by reinforcing zinc alloys with steel shots as described in the
patent-pending invention of U.S. File No. 07,314,950 flled Feb.
23, 1989.
In the preceding two examples, the bonding between steel shots
and matrix alloys was accomplished by using a flux of ammonium
chloride. Previously an inert or reducing atmosphere was
employed to induce bonding between the alloy matrix and fibers
coated with bondable metals such as copper, In an air atmosphere
such intermetallic bonding is not achieved~due to tlhe oxidabion
problem. The use of flux enables the bonding to be achieved in
air without the presence of bondable coating layer. Another
uniqueness of the fluxing method is that the flux is applied to
the molten liquid metal, not to the solid metal as has been done
in the past. The appropriate flux must clean surface oxides of
both the liquid alloy and reinforcing shots, thereafter forming
an instantaneous intermetallic bonding between the molten alloy
and shots. The uniqueness of flux in the present invention is
thus as follows.
(1) Surface oxides of both the molten alloy and steel shots are
cleaned by the flux in an air atmosphere.
(2) The fluidity of the molten liquid-state alloy covered with a
liquid flux layer provides the high mobility required to wet
the large number of shots in a very short time period.
(3) Immediately after surface oxides are removed, instantaneous
intermetallic bonding is achieved betveen shots and liquid
alloy.
(4) The presence of a protective flux layer on the molten alloy
surface negates the requirement of an inert or reducing
atmosphere for mixing. The air environment is just enough for
mixing with the aid of a flux.
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Generally, there are various kinds of fluxes: inorganic acid
fluxes, orqanic acid fluxes, and liquid rosin fluxes. In the
present invention, alternative acid fluxes will be introduced to
induce the wetting and ferroaluminum shots which are comprised
primarily of iron and aluminum will~be employed as reihforcement.
The advantages of ferroaluminum shots over conventional steel
shots are as follows. For certain applications such as lost core
plastic molding, it is desirable to reduce the weight of steel
shots for ease of handling and for reduction of energy
consumption. The handling problem becomes serious particularly
when the part made of fusible alloy is large. Such heavy product
is handled by a robot and very often, the clamping pressure of a
robotic arm induces indentation marks on the hot cast product
surface, rendering the cast surface damaged. In another example
involving zinc-based alloys, the reactivity of zinc with steel
is very high to form a solid cake and thus the suppression of
such reactivity is required to maintain the good melt-flow
property. The preceding problems can be solved by ferroaluminum
shots since iron-aluminum alloy shots are lighter than steel shots
and the reactivity is decreased by the presence of aluminum in
shots.
The problem of reactivity of zinc with steel or iron can be
overcome by satisfying the following two conditions. Firstly,
the aluminum content in the zinc alloy must be high enough to
reduce the reaction rate between zinc and iron. Secondly and
more importantly, the temperature of the molten zinc alloy must
be low enough to suppress the reaction between zinc and iron.
Both conditions are met by ferroaluminum shots when the molten
bath temperature is lower than about 850 degree F. Alternatively,
conventional steel shots can be mixed wlth zinc and then aluminum
is added quickly to stop the r~eaction ("melt-freeze" method) or
steel shots are mixed directly with zinc-aluminum alloy using an
acid flux comprised of chlorides and fluorides ("fluxing" method).
Generally the fluxing and "ferroaluminum" method are more
compatible with the conventional die casting process than the
melt-freeze method.
The kinds of metal matrix reinforcible with ferroaluminum
shots include not only zinc-based alloys but also tin-based,
lead-based, bismuth-based, copper-based, and aluminum-based
alloys. They can be used as gears, bearings, seals, bushings,
rollers, cams, guides, brackets, axle housings, fasteners, knobs,
inserts, housings, fusible links for fire sprinklers, thermal
plugs for valves or cylinders, cores for lost core plastic
molding, for work holding and work supporting, for accurate mold
cold work, for setting punches in press tools, for tube bending,
in die forming and jewellery manufacture, for proof casting and
lens blocking, for protective blocks for radiography, and any
static and dynamic parts requiring strength and creep resistance
using afore-mentioned alloys. The strength of such alloys
reinforced with shots is increased to help resist the creep or
cold flow tendency and the flowability is provided by spherical
shots.
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Su~mary of the Invention
Zinc-based, tin-based, bismuth-based, lead-based, copper-
based, aluminum-based, and any low-melting fusible alloys used
for structural and dynamic parts are wetted,by ferroaluminum shots
using inorganic acid fluxes such as zinc chloride, ammonium
chloride, a mixture of chlorides, or a mixture of chlorides and
fluorides. Other organic acid fluxes containing ammonium fluobo-
rate wor~ when they clean surface oxides of both matrix alloys and
shots. All the afore-mentioned alloys are wetted effectively by ~
steel or iron shots coated with sodium nitrite by using a chloride
based flux. Other shots wettable with the preceding alloys~by
using an acid-based flux include stainless steel, copper, nickel, V
monel, refractory metals, copper or nickel-coated steel, any copper
or nickel-coated ceramics, any nickel or copper-coated plastics,
any copper or nickel-coated metals, and any strong materials coated
with bondable metallic layers such as those listed above.
As reinforcement for zinc alloys, the content of aluminum in
ferroaluminum must be greater than a minimum in order to decrease
the reaction rate between iron and zinc to a negligible level.
The shot-reinforced alloys are then die-castable with the
surface smoothness comparable with the conventional unreinforced
alloys while improving the creep or cold flow behavior.
~ rass die casting alloys are also reinforcible with shots to
improve the creep behavior. Magnesium-based alloys require a
special flux under a nonoxidizing atmosphere for shots to be mixed.
Brief Description of Drawings
Fig.1 is a schematic illustration of a fusible thermal plug
comprised of two layers: one layer consists of matrix alloy and
the other layer consists of reinforcing shots embedded in the
matrix phase.
Fig.2 is a schematic illustration of a fusible alloy used in
a fire sprinkler system.
Detailed Description of the Invention
Iron-aluminum shots are fabricated by injecting a high pressure
water jet to the molten iron-aluminum alloy stream and quenching
into a water tan~. Shots contain other miscellaneous impurity
elements such as carbon, manganese , silicon, sulfur, and
phosphorous. Shots areicoated with sodium nitrite to prevent them
from environmental corrosion and also to help assist the bonding
reaction. The molten iron-aluminum bath is prepared by adding
aluminum or ferroaluminum to the steel bath and the size of shots
is controlled by adjusting various parameters such as shooting
angle, melt temperature, water jet pressure, diameter of water jet,
size of molten alloy stream, etc.
Ferroaluminum shots become bondable to the tin-based, bismuth-
based, lead-based, copper-based, zinc-based, and aluminum-based
alloyg by adding cleaning chemicals of zinc chloride, ammonium
chloride, a mixture of zinc chloride and ammonium chloride, and a
mixtuxe of chlorides and fluorides. For aluminum-based alloys and
zinc-based alloys containing aluminum, a mixture of zinc chloride,
ammonium chloride, and sodium fluoride is used as a flux.
Reinforcible alloys are not limited to the afore-mentioned alloys
but to any alloys whose melting point is lower than that of iron-
aluminum alloy shot and wettable by the alloy shots by means of
appropriate cleaning agent of flux. For example, magnesium-based
alloys containing aluminum can be reinforced with ferroaluminum
shots using a mixture of chlorides and fluorides as a flux under
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a protective atmosphere. In priciple, an appropriate cleaning
agent must clean (or remove surface oxides of) both the alloy shot
and matrix alloy in order to induce the intermetallic bonding
between them. Chloride-based acid fluxes are such cleaning agents
as exemplified in ammonium chloridet zinc chloride, etc. Other
inorganic acid or organic acid fluxes can work when they clean
surface oxides of both the matrix alloy and ferroaluminum shots.
Organic acids contain ammonium fluoborate as an ingredient.
The spherical shot geometry is the best shape in terms of good
melt-flow property and surface smoothness of a die cast product.
Other shapes such as particles, aggregates, or short fibers may be
applicable as reinforcement, but they easily produce voids, cracks,
rough surfaces, restricted flow in thin-sections, and blocking of
gates owing to the poor melt-flowability. Hybrid composites in
which various kinds of reinforcement are incorporated
~imultaneously utilize some or all of shots, particles, aggregates,
or short fibers as reinforcing agents. It is possible to maintain
the melt-flowability when the reinforcing agents consist of mostly
shots and a very small amount of particles or/and fibers.
As the strength increases with the increase of shot amount,
the amount of shots must be greater than a minimum for a desirable
strength improvement. However, as the content of shots rises, the
melt-flow behavior starts to deteriorate and hence the amount of
shots must be less than a maximum ~o maintain the good melt-flow
property. The precise magnitude of such minimum and maximum
depends on the shot size, kinds of matrix phase, kinds of shot
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material, and other process parameters.
The size of shots is determined by two factors: geometrical
complexity of a desired product and strength requirement. The
more complex the shape geometry, the finer the shot size and the
finer the shot diameter, the stronger the mechanical strength.
However, as the shot size decreases, the flow behavior tends to
deteriorate and thus the maximum mixable content of shots tends to
decrease. Consequently, there is an optimum condition in terms of
shot amount, shot size, strength requirement, and flow behavior
for a specific application. Generally, the diameter of shots
ranges from about 0.004 to 0.2 inch and when the size of shot is
much finer than the lower limit of 0.004 inch, the flow behavior
deteriorates rapidly as in the case of pPwder reinforcement so
that it is not die-castable.
Ferroaluminum shots are not the only kind of bondable
reinforcement to the afore-mentioned matrix alloys but also
conventional steel or iron shots coated with sodium nitrite and
sodium nitrite-coated ferroaluminum shots are bondable to the
matrix alloy. Other bondable reinforcements include stainless
steel, copper, nickel, cobalt, monel, refractory metals, copper-
coated steel, nickel-coated steel, copper or nickel-coated ceramics
, copper or nickel-coated plastics, copper or nickel-coated metals,
and any strong materials coated with bondable metallic layers
comprised primarily of copper or nickel. They are insoluble in
but wet by the preceding matrix alloys. The preceding
reinforcements generally require the presence of a flux for bonding.
~o~6
However, the bonding can take place without the presence of a
cleaning flux when the mixing process is performed under a
nonoxidizing (inert or reducing) environment and when reinforcing
shots are coated with copper or nickel which are bondable to the
matrix alloy. ~Conventional steel~or iron shots are mixed with the
afore-mentioned matrix alloys by using the flux of zinc chloride
or a mixture of zinc chloride or ammonium chloride. All the
preceding shots coated with sodium nitrite are also bondable to
the afore-mentioned alloys by using the chloride-based fluxes.
The function of sodium nitrite is twofold. It acts as a rust
inhibitor and also acts with chloride to generate a mixture of
nitric and hydrochloric acid so that the surface oxides can be
rapidly removed.
The advantages of ferroaluminum shots are light weight, easy
handling, energy saving, reduced reactivity with the matrix alloy
~particularly with zinc), and improved resistance to the
environmental corrosion.
For zinc alloys, the content of aluminum in ferroaluminum must
be greater than a minimum to suppress the reaction between zinc
and iron. When zinc chloride or ammonium chloride is used as a
flux, the iron-25 wt.~ aluminum alloy shot is mixable but the
ferroaluminum shot containing 75 wt.% aluminum is not mixable
and therefore, for high aluminum content shots, aluminum soldering
fluxes consisting of chlorides and fluorides are required.
Tin~based alloys are comprised primarily of tin and some or all
elements of lead, bismuth, antimony, cadmium, indium, and silver.
-- 2~C~779~
Lead-based alloys are comprised primarily of lead and some or all
elements of tin, bismuth, antimony, cadmium, indium, and silver.
Bismuth-based alloys are comprised primarily of bismuth and some
or all elements of tin, lead, antimony, cadmium, indium, and
silver. They are wettable with ferroaluminum or sodium nitriter
coated iron or st!eel shots using chloride-based fluxes such as
zinc chloride or ammonium chloride. For high aluminum content
ferroaluminum shots, aluminum soldering flux is employed. Using
aluminum fluxes, aluminum shots can be used as reinforcement for
lost core molding cores.
Zinc-based alloys are comprised of a major element of zinc and
a minor element of aluminurn together with copper and magnesium and
a trace amount of some or all elements of iron,lead, cadmium, tin,
titanium, nickel, and chromium. They are mixable with sodium
nitrite-coated iron or steel shots or ferroaluminum shots using
acid fluxes consisting of ammonium chloride, zinc chloride, and
sodium fluoride at temperatures lower than about 830 to 850 degree
F but higher than the melting points of zinc alloys and also the
working temperat~re of fluxes. For example, the melting point of
zinc plus 3.5 - 4.3 wt.% aluminum alloy ranges from 718 to 727
degree F.
Copper-based alloys are comprised primarily of copper and
some or all elements of zinc, tin, lead, iron, alurninum, manganese,
and silicon. Aluminum-based alloys are comprised primarily of
aluminum and some or all elements of tin, silicon, iron, copper,
and nickel. They are wetted with ferroaluminum or steel shots
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coated with sodium nitrite using chloride-based fluxes.
Magnesium-based alloys are comprised of a major element of
magnesium and a minor element of aluminum together with a trace
amount of zinc, silicon, manganese, and copper. Shots are mixed
under an inert atmosphere usingia special flux consisting of
magnesium chloride and other chlorides. Applications include wheels
, transmission housings, crank cases~ chain saws, lawn mower decks,
tools, etc.
One example of organic acid-based flux is comprised of
aminoehtylethanolamine, ammonium fluoborate, and zinc oxide.
For ferroaluminum shots or conventional iron or steel shots, a
chloride-based eutectic flux comprised of potassium chloride and
zinc chloride is a good cleaning agent especially for zinc alloys
since it produces no toxic gases.
Alternative shots for reinforcement are steel, iron, chromium,
and titanium. Another alternative shots are alloys based on iron,
steel, nickel, cobalt, chromium, titanium, aluminum, copper, or
refractory metals, which are bondable to the afore-mentioned matrix
alloys by using a chloride-based flux. For example, iron-based
alloys comprised of iron and carbon and a tiny amount of silicon
or magnesium àre bondable to the matrix alloy by employing a chloride
-based flux. In short, any strong metal shots comprised of one or
more metallic elements can be used as reinforcement when they become
bondable by means of a flux.
For zinc alloys, the density of cast iron shots is controlled
to be about equal to the specific gravity of matrix alloy by
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2~ t~7s~
adjusting the carbon content such that the iron shots can be
dispersed homogeneously. The reactivity of iron shots wi.th zinc is
also reduced by increasing the carbon content~ The density of
ferroaluminum shots can also be controlled by adjusting the aluminum
content. The aluminum content in ferroaluminum shots varies
depending on specific applications but generally it ranges from 0.1
to 99 weight ~.
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2~ 796
Thermal Pluq Application
When the density of reinforcing steel, iron, or ferroaluminum
shots is different from that of the matrix phase alloy, two
slightly ~ifferent~layers are formed in the cavity hole of a
thermal plug filled with a fusible alloy as illustratèd in Fig.;1.
The degree of morphological contrast depends on the filling method
and if rapidl~ solidified, uniform morphology can be obtained.
The dense layer 2 provides the extra strength to resist the
extrusional flow under a high gas pressure and the loose layer 1
seals the plug additionally to prevent any gas leakage. When the
fusible alloys are reinforced with particles or short fibers, the
gas leakage tends to occur owing to the poor flowa~ility-induced
voids or/and cracks. Cracks often occur from the torque applied
to tighten the plug.
As a fusible thermal plug for natural gas cylinders, medical
ga~ cylinders, acetylene aylinders, carbon dioxide cylinders, or
any gas cylinders or their valves, matrix alloys fusible at about
212 ~r 165 degree F are mixed with steel or ferroaluminum shots
and filled into the plug cavity using appropriate fluxes. Such
plugs resist the extrusional flow at 130 degree F under a gas
pressure of about 3600 psi for at least 24 hours with the alloy
fusing at about 212 degree F, for example. The improved creep
strength without any extrusional flow enables the installation of
a thermal plug in conjunction with pressure-sensitive rupture
disc in a pressure gas cylinder valve such as carbon dioxide
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2Q~ 96
aluminum cylinder to safeguard the safety against temperature as
well as pressure. Accordingly, a fatal catastrophe which happens
when the rupture disc blocks the release of pressurized gas in a
cylinder can be prevented. Partially filled aluminum cylinders
are particularly dangerous when only the pressure-sensiti;ve rupture
disc is available for safety. The availability of temperature-
sensitive thermal plug in addition to pressure-sensitive rupture
disc will guarantee the safety against both the pressure and
temperature independently. ~
Small amount`of particles or fibers can be added when they do
not degrade the f1owabi1ity.
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Fire Sprinklers
For use as fusible links of fire sprinklers, the melting
point of fusible alloys varies according to the requirements of
a specific application'and generally the fusing temperature is
less than about 600 degree F. As the strength of new creep-
resistant alloys is higher than conventional fusible alloys, the
mass or dimension of fusible links in a sprinkler system can be
reduced to decrease the response time in case of fire. The
increase of creep strength also eliminates the problem of
premature failure of a sprinkler system since the fusible link
is under a continuous load until it melts due to fire. As
shown in Fig.2, the new alloy consists of conventional matri:~
1 reinforced with steel or ferroalumnum shots 2.
Small amount of particles or fibers can be added when they do
not degrade the flowability.
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Die Cast Zinc AlloYs
The reactivity of iron with zinc is significantly reduced
when the aluminum content in the melt is greater than about 3 wt.
% and accordingly, ferroaluminum shots having the aluminum content
greater than about 3 wt.~ are mixed with conventional zinc alloys
such as number 3, number 5, number 7, number 16, ZA 8, and ZA 12.
Since the strength comes from strong shots, the cheap hot chamber
process may be applicable for the whole range of zinc alloys when
the processing temperature is lower than about 830 to 850 degree F.
The maximum amount of shots without degrading the flowability is
about 30 to 40 wt.% and depending on the kinds of zinc alloy matrix
, a range of strengths can be obtained.
Alternatively, conventional zinc aluminum alloys are mixable
with conventional steel or iron shots by using a flux comprised of
zinc chloride, ammonium chloride, and sodium fluoride at about 780
to 820 degree F. A crude method of manufacturing shot-reinforced
zinc alloys is-to coat steel skots with the zinc layer and then
add the 2inc-coated shots to the zinc-aluminum melt in such a way
that the total aluminum content in the melt is greater than about
3 wt.~ to suppress the reaction of zinc with iron. -
Generally, steel or ferroaluminum shots can be mixed with thezinc-based matrix alloys by employing any fluxes that become active
below about 850 degree F but above the melting temperature of zinc
alloys and also that can effectively remove surface oxides of both
shots and matrix phase alloy. The melting point o~ zinc alloys
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ranges from 710 to 910 degree F. For example, zinc plus 3.~-4.3
wt.~ aluminum alloy melts at 718 to 727 degree F and zinc plus
25-28 wt.~ aluminum alloy melts at 707 to 909 degree F.
Regardless of the kinds of zinc alloy, the processing temperature
must be less than about 830 to 850 degree F in order for iron,
steel, or ferroaluminum shots to be mixed without undesirable
reaction between zinc and iron.
Potential applications include any zinc alloy products used
under a constant stress above room temperature, for bolting
applications such as fasteners and brackets, and under the hood
application in automobile or vehicles. The prospective zinc alloys
must be processed below about 850 degree F and thus the number 3,
number 5, number 8, number 16, ZA 8 and ZA 12 alloys are some of
candidates to be reinforced with shots to improve the creep
behavior and additionally to reduce the production cost.
For gravity casting, small amount of particles or fibers can be
added when the melt-flowability is not degraded. Cast iron shots
with high carbon content are bondable to zinc alIoys usinlg the
eutectic flux comprised of potassium chloride and zinc chloride.
Zinc alloys contain a small amount of magnesium to improve the
oxidation resistance and a small content of copper to enhance the
strength.
Conventional iron shots bonded and immersed in the zinc-
aluminum alloy melt can have a density close to that of the matrix
alloy by adjusting the amount of minor elements such as carbon and
aluminum.
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Lost Core Plastic Moldinq
When tin-bismuth or tin-lead-antimony alloys are reinforced
with ferroaluminum shots, the weight of die-cast cores is reduced
due to the~aluminum content.~ The light weight of core eases the
problem of handling and helps the decoring process by floating to
the surface. Although ferroaluminum shots are lighter than tin
based matrix alloys, the die casting process produces a self-
turbulant flow for homogeneous mixing of shots in the matrix alloy
for a uniform strengthening effect.
Sodium nitrite-coated steel, iron, or ferroaluminum shots
become bondable to the tin-based or bismuth-based fusible alloys
by using zinc chloride or a mixture of zinc chloride and ammonium
chloride. Aluminum shots without any bondable metal coating such
as copper are mixed directly with fusible alloys by using an
aluminum flux comprised of ammonium chloride, zinc chloride, and
sodium fluoride or by using an eutectid flux comprised of potassium
chloride and zinc chloride~ Conventional steel or iron shots are
bondable to tin or bismuth-based alloys by using a flux of
ammonium chloridelor a mixture of zinc chloride and ammonium
chloride. Small amount of particles or fibers can be added when
they do not degrade the flowability.
37~
Example 1. Zinc Alloys
Zinc-aluminum alloys are mixed with steel or iron shots using
an acid flux comprised of ammonium chloride, zinc chloride, and
sodium fluorlde. The zinc alloys are also mixable with ~ !
ferroaluminum shots using the same flux at about 800 degree F. The
amount of shots is about 25 to 30 wt.% and the size of shots ranges
from 0.004 to 0.1 inch in diameter. In order to maintain the melt
temperature below about 850 degree F, the content of aluminum in
zinc alloys is limited to below about 10 wt.%.
The kinds of zinc alloys mixable with shots are as follows:
(1) About 3.5-4.3 wt.% aluminum, about 0.25 wt.% copper, about
0.02-0.05 wt.% magnesium, and remainder zinc (number 3 alloy).
(2) About 3.5-4.3 wt.% aluminum, about 0.75-1.25 wt.% copper,
about 0.03-0.08 wt.% magnesium, and remainder zinc (number 5
alloy).
(3) About 3.5-4.3 wt.% aluminum, about 0.25 wt.% copper,
about 0.005-0.02 wt.~ magnesium, about 0.005-0.02 wt.% nickel,
and remainder zinc (number 7 alloy).
(4) About 0.01-0.04 wt.% aluminum, about 1.0-1.5 wt.% copper,
about 0.02 wt.% magnesium, about 0.15-0.25 wt.% titanium,
about 0.1-0.2 wt.% chromium, and remainder zinc (number 16
alloy).
~5) About 8.0-8.8 wt.~ aluminum, about 0.8-1.3 wt.% copper,
about 0.03-0.015 wt.% magnesium, and remainder zinc (ZA 8).
(6) About 10.5-11.5 wt.% aluminum, about 0.5-1.25 wt.% copper,
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about 0.015-0.03 wt.~ magnesium, and remainder zinc (ZA 12).
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~a7~96
Example 2. Tin alloys
Composite alloys comprised of tin-based matrix alloy
reinforced with ferroaluminum shots~are fabricated by using a flux
of zinc chloride. The content of shots is about 30 to 45 wt.% and
the size of shots ranges from 0.004 to 0.1 inch in diameter. Some
examples of the tin-based matrix phase are as follows.
(1) About 89 wt.% tin, about 7.5 wt.% antimony, and about 3.5 wt.%
copper.
(2) About 59 wt.% tin, about 38 wt.~ lead, and about 3 wt.%
antimony.
(3) About 10 wt.~ bismuth, and about 90 wt.% tin.
Sodium nitrite-coated steel shots are also mixed with tin alloys
using ammonium chloride or zinc chloride with the shot content
being about 30 to 45 wt.% of the composite alloy.
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Example 3. Bismuth Alloys
Composite alloys comprised of bismuth-based matrix alloy
reinforced with ferroaluminum shots~are fabricated using a flux
of zlnc chlorlde or a mixture of ammonium chloride and zinc
chloride. The content of shots is about 30 to 45 wt.% of-the
composite alloy and the size of shots ranges from 0.004 to 0.1
inch in diameter. Sodium nitrite-coated steel shots are also
mixed with bismuth alloys using chloride-based fluxes. Some
examples of matrix compositions are as follows.
(1) About 54 wt.~ bismuth, about 26 wt.% tin, and about 20 wt.
cadmium.
(2) About 50 wt.~ bismuth, about 27.8 wt.% lead, about 12.4 wt.
tin, and about 9.3 wt.% cadmium.
(3) About 57 wt.% bismuth, about 17 wt.% tin, and about 26 wt.%
indium.
~4~ About 57 wt.% bismuth, and about 43 wt.% tin.
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Example 4. Copper Alloys
Composites consisting of copper-based matrix alloy reinforced
with ferroaluminu~ shots or sodium nitrite-coated steel shots
are fabricated using a flux of ~inc chloride or a mixture of
zinc chloride and ammonium chloride. The content of shots is
about 20 to 30- wt.~ of the composite alloy and the size of shots
ranges from 0.004 to 0.1 inch in diameter.
One example of matrix compositions is about 58-63 wt~ copper,
about 1.0 wt.% tin, about 0.5-2.5 wt.% lead, about 0.5 wt.% iron,
about 0.2-0.8 wt.% aluminum, about 0.5 wt.% manganese, and about
0.5 wt.% silicon.
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2(~ '7~6
Example 5. Aluminum Alloys
Composites comprised of aluminum-based alloy matrix reinforced
with ferroaluminum shots are fabricated by using a flux consisting
of ammonium chloride, zinc chloride, and sodium fluoride, or by
a mixture of zinc chloride and ammonium chloride. Sodium nitrite-
coated steel shots are also bondable using the preceding fluxes.
The content of shots is about 20 to 30 wt.% and the diameter of
shots ranges fro~ 0.004 to 0.1 inch. The composition of aluminum
alloy is, for example, about 80 wt.% aluminum, and about 20 wt.%
tin together with small additions of silicon, iron, copper, and
nickel.
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~Q~7~
Example 6. Lead Alloys
Composites comprised of lead-based alloy matrix reinforced
with steel shots, sodium nitrite-coated steel or iron shots, or
ferroalumihum shots are fabricated using a flux consisting of a
mixture of zinc chloride and ammonium chloride. The content of
shots is about 30 to 40 wt.% of the composite alloy and the
diameter of shots ranges from 0.004 to 0.1 inch. One example of
lead alloy is about 83 wt.% lead, about 15 wt.% antimony, and about
1 wt. % tin.
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7~
Example 7. Magnesium Alloys
The matrix alloy is comprised of about 9.0-10.5 wt.~ aluminum,
about 0.3-1.0 wt.% zinc, about 0.3 wt.% silicon, abouL 0.15-0.4
wt.% manganese, about 0.15 wt.~ copper, and remainder magnesium.
Steel or ferroaluminum shots are mixed with the magnesium alloy
under an inert nitrogen atmosphere using a flux consisting of
chlorides~and fluorides.
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96
Although but seven embodiments of the present investigation
have been illustrated and described, it will be apparent to those
skilled in the art that various changes and modifications may be
mad~ therein without departing from the spirit of the invention. , , (-
