U.S. patent application number 13/638772 was filed with the patent office on 2013-04-25 for method for producing shaped bodies from aluminium alloys.
This patent application is currently assigned to Technische Universitat Wien. The applicant listed for this patent is Herbert Danninger, Christian Gierl, Johan Ter Maat, Branislav Zlatkov. Invention is credited to Herbert Danninger, Christian Gierl, Johan Ter Maat, Branislav Zlatkov.
Application Number | 20130101456 13/638772 |
Document ID | / |
Family ID | 44170208 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130101456 |
Kind Code |
A1 |
Danninger; Herbert ; et
al. |
April 25, 2013 |
Method for Producing Shaped Bodies from Aluminium Alloys
Abstract
The invention pertains to a method for producing molded articles
based on aluminum alloys by metal injection molding, comprising the
following steps: a) producing a feed-stock by mixing the metals
contained in the desired alloy in the form of metal powders and/or
one or more metal alloy powders with a binder; b) producing a green
body by injection molding said feedstock; c) producing a brown body
by at least partially removing the binder from the green body by
catalytic and/or solvent and/or thermal debinding; d) sintering the
at least partially debound brown body to obtain the desired molded
article; characterized in that, in step c), the binder is
completely removed, wherein thermal debinding is carried out to
remove the (residual) binder, optionally after having carried out
one or more previous debinding steps, said thermal debinding being
carried out in an atmosphere containing at least 0.5% by volume of
oxygen, whereafter the thus obtained, completely debound brown body
is sintered.
Inventors: |
Danninger; Herbert; (Wien,
AT) ; Gierl; Christian; (Wien, AT) ; Zlatkov;
Branislav; (Wiener Neustadt, AT) ; Ter Maat;
Johan; (Mannheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Danninger; Herbert
Gierl; Christian
Zlatkov; Branislav
Ter Maat; Johan |
Wien
Wien
Wiener Neustadt
Mannheim |
|
AT
AT
AT
DE |
|
|
Assignee: |
Technische Universitat Wien
Wien
AT
Rubert Fertinger GMBH
Wolkersdorf
AT
BASF SE
Ludwigshafen
DE
|
Family ID: |
44170208 |
Appl. No.: |
13/638772 |
Filed: |
March 31, 2011 |
PCT Filed: |
March 31, 2011 |
PCT NO: |
PCT/AT2011/000157 |
371 Date: |
December 13, 2012 |
Current U.S.
Class: |
419/30 |
Current CPC
Class: |
B22F 3/225 20130101;
B22F 3/1021 20130101; C22C 1/0416 20130101; B22F 3/12 20130101 |
Class at
Publication: |
419/30 |
International
Class: |
B22F 3/12 20060101
B22F003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2010 |
AT |
A 534/2010 |
Claims
1. A method for producing molded articles based on aluminum alloys
by metal injection molding, comprising the following steps: (a)
producing a feedstock by mixing the metals contained in the desired
alloy in the form of metal powders and/or one or more metal alloy
powders with a binder; (b) producing a green body by injection
molding said feedstock; (c) producing a brown body by at least
partially removing the binder from the green body by catalytic
and/or solvent and/or thermal debinding; (d) sintering the at least
partially debound brown body to obtain the desired molded article;
wherein in step (c), the binder is completely removed, wherein
thermal debinding is carried out to remove residual binder,
optionally alter having carried out one or more previous debinding
steps, said thermal debinding being carried out in an atmosphere
containing at least 0.5% by volume of oxygen, whereafter the thus
obtained, completely debound brown body is sintered.
2. The method according to claim 1, wherein in addition to
aluminum, the aluminum alloy contains one or more metals selected
from the group consisting of magnesium, copper, silicon, and
manganese.
3. The method according to claim 1 or claim 2, wherein in addition
to aluminum, the aluminum alloy contains one or more metals at a
percentage of 0.5 to 25% by weight, respectively.
4. The method according to claim 1, wherein the metal(s) is/are
used as (a) master alloy powder(s).
5. The method according to claim 1, wherein the binder is a
polyacetal-based binder.
6. The method according to claim 5, wherein the binder consists of
50 to 95% of polyacetal.
7. The method according to claim 5, wherein the binder consists of
80 to 90% of polyacetal.
8. The method according to claim 1, wherein step (c) only includes
thermal debinding in the presence of oxygen, which is carried out
in one or more steps and removes the entire binder.
9. The method according to any one of the claim 1, wherein step (c)
includes solvent debinding to remove the main part of the binder,
followed by said thermal debinding to remove the residual
binder.
10. The method according to any one of the claim 1, wherein step
(c) includes catalytic debinding to remove the main part of the
binder, followed by said thermal debinding to remove the residual
binder.
11. The method according to claim 10, wherein the catalytic
debinding is carried out in the presence of at least one acid
selected from the group consisting of nitric acid, oxalic acid,
formic acid, and acetic acid.
12. The method according to claim 11, wherein the acid is
sublimated oxalic acid.
13. The method according to claim 1, wherein, said thermal
debinding to remove any residual binder is carried out at a
temperature below 500.degree. C.
14. The method according to claim 13, wherein said thermal
debinding to remove any residual binder is carried out applying a
specific temperature profile ranging between 100 and 420.degree.
C.
15. The method according to claim 13 or claim 14, wherein that the
heating rate during said thermal debinding process for removing the
residual binder does not exceed 5 K/min.
16. The method according to claim 15, wherein the heating rate does
not exceed 1 to 2 K/min.
17. The method according to claim 1, wherein in step (d), the
completely debound brown body is sintered while forming a liquid
phase.
18. The method according to claim 17, wherein sintering is carried
out at a temperature between the solidus and the liquidus
temperatures of the respective aluminum alloy.
19. The method according to claim 1, wherein the heating rate to
reach the sintering temperature after said thermal debinding step
ranges from 4 to 20 K/min.
20. The method according to claim 5, wherein the polyacetal-based
binder is a polyoxymethylene binder.
Description
[0001] The metal injection molding technology experienced a boom in
recent years and has become an established technology for producing
complex small parts, generating a worldwide annual turnover of
approximately EUR 1 billion. The combination of the molding
technology applied for plastic injection molding with various
materials used in powder technology has opened up interesting new
markets for many materials.
[0002] The production method essentially comprises the process
steps described below. At first, a feedstock in the form of an
injectable granulate, which consists of metal powder and a plastic
component comprising at least two intimately mixed polymer
components, is produced. This feedstock is then molded by plastic
injection molding machines to obtain molded articles. These so
called "green bodies" usually contain approx. 40% by volume of a
plastic binder, which is largely removed in the subsequent so
called debinding (or "debindering") step. A residual binder
component, the so called "backbone", remains and guarantees the
residual strength of the article after defending. The defending can
be achieved in various ways, for example thermally, using solvents,
catalytically, etc., the selected process being carefully adapted
to the plastic binder used in the granulate. After debinding, the
article, the so called "brown body", is subjected to a sintering
process, in the first step of which the residual "backbone" binder
is usually thermally removed, whereafter the article is sintered
and shrinks to form a nearly compact metal component. This
technology is currently applied to high- and low-alloy steels,
precious metals, hard metals, but also to ceramics.
[0003] Metal injection molding for aluminum materials has not yet
been successfully established in industry, although there are
patents relating to this technology; this is due to the fact that
the sinter mechanisms of aluminum alloys are completely different
from those of the above mentioned materials. Non-reducible oxides
on the surface of aluminum powders constitute significant obstacles
to sintering. For this reason, publications only describe an
oxygen-free atmosphere.
[0004] A particular difficulty in connection with the above
described processing of aluminum relates to the relatively low
melting point of aluminum (660.degree. C.), which is further
lowered when alloying elements such as tin are added thereto. This
results in the problem that debinding of the plastic component has
to be completed at very low temperatures, making the suitable
process time frame often too short for guaranteeing the plastic
component's complete removal. If the plastic component is not
completely removed, undesired reactions of organic residual
components with metal components may take place, which interfere
with the sintering process and thus impair the mechanical
characteristics obtainable by the method.
[0005] Liu et al. in Powder Metallurgy 51, 78-83 (2008) describe a
method in which tin, as an alloying metal, and magnesium blocks are
added, the magnesium serving as "sacrificial metal", i.e. as an
oxygen and humidity trap.
[0006] Against this background, the aim of the present invention
consisted in developing a metal injection molding process for
producing molded articles of aluminum materials with good
mechanical characteristics in a simple and reproducible way.
DISCLOSURE OF THE INVENTION
[0007] The inventors have achieved this aim by providing a method
for producing molded articles based on aluminum alloys by metal
injection molding, said method comprising the following steps:
[0008] a) producing a feedstock by mixing the metals contained in
the desired alloy in the form of metal powders and/or one or more
metal alloy powders with a binder;
[0009] b) producing a green body by injection molding the
feedstock;
[0010] c) producing a brown body by at least partially removing the
binder from the green body by catalytic and/or solvent and/or
thermal debinding;
[0011] d) sintering the at least partially debindered brown body to
obtain the desired molded article;
the method of the invention being characterized in that the binder
is completely removed in step c), wherein thermal debinding is
carried out to remove the (residual) binder, optionally after
having carried out one or more previous debinding steps, said
thermal debinding being carried out in an atmosphere containing at
least 0.5% by volume of oxygen, whereafter the thus obtained,
completely debound (or debinded or debindered) brown body is
sintered.
[0012] This method yields highly pure molded articles of aluminum
alloys, as, due to the complete removal of the binder in step c),
there are no undesired reactions of the plastic material with the
alloying metals. The complete removal of the binder is achieved due
to the presence of oxygen in the atmosphere, even at relatively low
temperatures. Contrary to current teachings, according to which the
presence of oxygen is to be absolutely prevented, the inventors
have found that a small portion of oxygen, of at least 0.5% by
volume, does not significantly increase the oxidation of the
aluminum, but contributes to a faster and complete debinding.
Depending on the composition of the powder mixture and the
temperature conditions, an oxygen content, for example, between 20
and 100% by volume is applied, which means that it is even possible
to use pure O.sub.2 gas.
[0013] In addition to aluminum, the aluminum alloy contains one or
more other metals which are not subject to any specific
limitations. The alloy partners are preferably selected from the
group consisting of magnesium, copper, silicon, and manganese, and
are particularly preferably contained at proportions of 0.5 to 25%
by weight, in order to obtain molded articles having the desired
characteristics. Metals such as bismuth, tin, lead, indium, or
zinc, or alloys such as Wood's metal, which have significantly
lower melting points and which, in some cases, may serve as
sintering aids lowering the temperature at which melting starts,
are not required according to the present invention, but may still
be added as alloying partners, if desired, in order to obtain
sintered bodies of the respective alloys. It is particularly
advantageous to use the other metals in the form of alloys with
aluminum, i.e. as so-called master alloy powders.
[0014] According to the present invention, it is preferred to use
binders which are known to be removable at low temperatures,
polyacetal-based binders, e.g. poly(oxymethylene) (POM) binders,
are particularly preferred, for example as disclosed by BASF in EP
413,231, WO 94/25205, and particularly in EP 446,708, and
commercially available under the trademark Catamoid.RTM.. It is
desirable for the binder to have a high polyacetal percentage,
consisting preferably of 50 to 95%, even more preferably of 80 to
90%, of polyacetal to promote the fast and complete removability at
low temperatures and in the presence of oxygen. Alternatively,
binder systems based on wax and polymers may be used, the wax as
the main component being removed by a preceding solvent debinding,
i.e. before carrying out the thermal debinding in the presence of
oxygen according to the invention.
[0015] The debinding in step c) of the method of the invention may
comprise a single thermal debinding step in the presence of oxygen
in which the binder is completely removed. Alternatively, one or
more preceding debinding steps may be carried out to remove the
main proportion of the binder, followed by the thermal debinding
step of the invention to remove the residual binder in the presence
of oxygen. A preceding debinding step may also be a thermal
debinding step--in the absence or also in the presence of oxygen.
This means that it is also possible to carry out a multi-step
thermal debinding process using different process parameters for
debinding--for example at different temperatures or in different
atmospheres, for example without and with oxygen or with air or
with pure oxygen, etc.
[0016] In preferred embodiments of the invention, catalytic
debinding and/or solvent debinding is carried out before the
thermal debinding to remove the residual binder in the presence of
oxygen in step c). In these preceding debinding steps, the main
part of the binder is already removed from the composition so that
only the "backbone" component remains to be removed by the
subsequent thermal debinding.
[0017] Catalytic debinding is preferably carried out in the
presence of at least one acid selected from nitric acid, oxalic
acid, formic acid, and acetic acid, as these acids accelerate the
complete removal of the preferred polyacetal binders by acidolysis
without leading to undesired side reactions with the alloy
components. In the case of solvent debinding, the main part of the
binder is removed by extraction with a suitable solvent or mixed
solvent, e.g. acetone, n-heptane, water, etc. According to the
present invention, it is particularly preferred to apply catalytic
debinding using sublimated oxalic acid.
[0018] As already mentioned above, the thermal debinding process
for removing the residual binder in step c) is carried out at a
relatively low temperature in order to avoid oxidation reactions,
particularly of the aluminum contained in the powder mixture. A
relatively low temperature herein refers to a temperature which is
significantly lower than the melting point of aluminum, preferably
below 500.degree. C., more preferably between 100 and 420.degree.
C. It is particularly preferred to set a temperature profile
optimized for the respective powder mixture, providing for a
heating rate of not more than 5 K/min, more preferably of not more
than 1 to 2 K/min. In this way, the mixture to be debound is heated
gently and homogeneously.
[0019] The sintering step d) of the method of the invention is not
subject to any specific limitations, except for the fact that the
binder has to be completely removed beforehand. It is preferred,
however, to carry out the sintering step upon formation of a liquid
phase, as will be described in further detail below.
[0020] The known technology of producing molded articles of
aluminum alloys by powder metallurgy compression molding processes
is based on the theoretical assumption that the compression process
mechanically damages the surface of the alumina-covered aluminum
particles in the matrix, said damage allowing for a metallurgic
reaction. However, a (completely) debound brown body obtained by
injection molding de facto is a packed bed of metal powder, the
oxide skins of the metals not being subject to any mechanical load
and thus not being subject to this known mechanism. This means that
there are no direct metal-metal contacts between the powder
particles. Nevertheless, by appropriately selecting the sintering
conditions, the method of the invention succeeds in achieving the
required shrinking in which the compaction of the sintered body
becomes manifest, and thus succeeds in obtaining molded parts
having been compacted to the greatest possible extent.
[0021] Therefore, according to the invention, embodiments are
preferred in which, in step d), the completely debound brown body
is sintered while forming a liquid phase. Without wishing to be
bound by any theory, the inventors believe that the liquid phase,
which is partly intermediary, but mainly stationary, i.e. is in a
state of thermodynamic equilibrium with the solid Al phase,
establishes the required contact between the metals in the powder
mixture via microcracks, micropores or similar "openings" in the
oxide skins of the metal powder particles and by creeping under the
oxide skins, and thus it promotes the formation of a highly
compacted sintered body out of the completely debound brown body.
It is particularly preferred to carry out the sintering in step d)
at a temperature between the solidus and the liquidus temperatures
of the respective aluminum alloy, so that, at every point in time
during the sintering process, a portion of the alloying-metals,
which can be controlled by selecting the adequate temperature
profile, is in a liquid state, which efficiently prevents a loss of
dimensional stability.
[0022] The composition of the respective atmospheres in the
individual steps of the inventive method is not subject to any
specific limitations, except for the presence of oxygen for thermal
debinding in step c); those skilled in the art are capable of
selecting the atmosphere which is best suited for the respective
powder mixture for each step, vacuum also being an option. However,
the sintering step d) is preferably carried out in an extremely
dry, nitrogen-containing atmosphere, i.e. in pure nitrogen, under
normal pressure or under reduced pressure ("partial pressure
sintering"), or in a mixture of nitrogen and pure inert gas
(helium, argon), preferably having a dew point below -40.degree.
C., as the presence of nitrogen significantly promotes the powder
particles' wettability with the developing metal melt.
[0023] The sintering step may be optionally followed by a suitable
additional treatment by which the finished molded parts are kept in
the desired shape. It is, for example, possible to apply the known
hot isostatic pressing (HIP) process in order to achieve the
desired final density of the molded parts. In this process,
residual pores which are still present after the sintering step are
sealed under the influence of external gas pressure and high
temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a photograph of the green body (top) and of the
sintered body (bottom) obtained therefrom in Example 9.
[0025] FIG. 2 is a photograph of the green body (left) and the
sintered body (right) obtained therefrom in Example 10.
[0026] The invention will be described in further detail below,
referring to non-limiting specific exemplary embodiments.
EXAMPLES
[0027] All the feedstocks produced in the examples below were
homogenized in a heated laboratory compounder at 190.degree. C.
Bars for tensile tests or hollow cylinders, respectively, were
formed from these feedstocks by injection molding according to ISO
2740, applying the method of the invention as described below. A
hydraulic injection molding machine (Battenfeld HM 600/130) with
PIM equipment was used for producing the green bodies.
[0028] In a first step, the feedstock was at first filled into the
funnel of the injection molding machine. The injection molding
process for producing the green bodies comprised the following
steps: Using a heated injection cylinder with a rotating screw
inside, the pretreated charging material was plastified and
predosed according to preset parameters (including, for example,
rotational speed, dosing volume, back pressure, etc.). Then the
predosed amount was injected into an adequately tempered
instrument. Depending on the feedstock and the binder used therein,
the plastification temperature in the injection cylinder ranged
between 120 and 220.degree. C., while the temperature inside the
instrument was between 25 and 140.degree. C. After a sufficiently
long cooling period, the injection molding instrument was opened
and the green body was discharged from and taken out of the
instrument using a handling device.
Example 1
Tensile Test Bars: Solvent Debinding/Thermal Debinding
[0029] A commercially available metal powder mixture (Alumix.RTM.
231 from Ecka), consisting of aluminum with 14% by weight of
silicon, 2.5% by weight of copper, and 0.6% by weight of magnesium,
was thoroughly mixed with a solvent binder consisting of
wax/thermoplastic to obtain a feedstock.
TABLE-US-00001 Feedstock component Percentage (% by weight) Alumix
231 powder* 74.8 Solvent binder: wax proportion 14.8 Solvent
binder: thermoplastic proportion 8.2 Stearic acid 2.2 100.0
*commercially available metal powder mixture of aluminum and 14% by
weight of silicon, 2.5% by weight of copper, and 0.6% by weight of
magnesium (from Ecka)
Debinding and Sintering of the Tensile Test Bars
[0030] This feedstock was first debound by solvent extraction using
acetone in a 60 l oven at 45.degree. C. in 12 h.
[0031] The thus obtained brown body contained approximately 14.5%
by weight of residual binder, which was subsequently removed by
thermal debinding according to the invention in an atmosphere
containing pure oxygen, applying a temperature profile ranging from
150.degree. C. to 320.degree. C. for 1 h and then from 320 to
420.degree. C. for 1.5 h. The thus completely debound brown body
was then sintered within 1 h at 560.degree. C. in pure nitrogen
(dew point: -50.degree. C.).
Results
[0032] Length shrinkage: 11.6% [0033] Shrinkage of the bars'
diameter: 12.25% [0034] Sintered density: 2.36 g/cm.sup.3
Example 2
Tensile Test Bars: Thermal Debinding in a Single Step
TABLE-US-00002 [0035] Feedstock component Percentage (% by weight)
Aluminum powder 67.1 Master alloy powder* 4.3 POM binder 25.8
Lucryl G55** 2.8 100.0 *master alloy consisting of 50/50 aluminum
and magnesium **commercially available poly(methylmethacrylate)
(PMMA; from BASF)
Debinding and Sintering of the Tensile Test Bars
[0036] Complete thermal debinding was carried out in a 40 l oven in
the presence of 200 l/h of pure oxygen according to the following
debinding profile: [0037] heating to 130.degree. C. at a heating
rate of 2 K/min [0038] temperature maintained at 130.degree. C. for
4 h [0039] heating to 200.degree. C. at a heating rate of 2 K/min
[0040] temperature maintained at 200.degree. C. for 5 h [0041]
heating to 420.degree. C. at a heating rate of 2 K/min [0042]
temperature maintained at 420.degree. C. for 4 h
[0043] The weight lost during thermal debinding amounted to
24.2%.
[0044] Then the bars were sintered for 1 h in pure nitrogen, the
oven temperature being set to 665.degree. C. and amounting to
approximately 630.degree. C. inside the oven.
Results
[0045] Length shrinkage: 12.27% [0046] Shrinkage of the bars'
diameter: 14.52% [0047] Sintered density: 2.46 g/cm.sup.3
Example 3
Tensile Test Bars: Double Thermal Debinding
TABLE-US-00003 [0048] Feedstock component Percentage (% by weight)
Aluminum powder 70.1 Magnesium powder 2.2 POM binder 24.0
Surfactant* 3.7 100.0 *ethoxylated C.sub.13-C.sub.15-oxoalcohol
having 7 EO-units
Debinding and Sintering of the Tensile Test Bars
[0049] At first, a first thermal debinding was carried out in a 50
l oven in 500 l/h of air at 180.degree. C. for 14 h. Weight loss:
27.0%.
[0050] Thereafter, a second thermal debinding was carried out at a
temperature of up to 420.degree. C. in pure nitrogen within 1 hour,
again followed by sintering for 1 h at an oven temperature set to
665.degree. C.
Results
[0051] Length shrinkage: 9.5% [0052] Shrinkage of the bars'
diameter: 11.4% [0053] Sintered density: 2.13 g/cm.sup.3
Example 4
Tensile Test Bars: Catalytic/Thermal Debinding
TABLE-US-00004 [0054] Feedstock component Percentage (% by weight)
Aluminum powder 70.1 Magnesium powder 2.2 POM binder 24.0
Surfactant* 3.7 100.0 *ethoxylated C.sub.13-C.sub.15-oxoalcohol
having 7 EO-units
Debinding and Sintering of the Tensile Test Bars
[0055] At first, catalytic debinding was carried out in a 50 l oven
using 2% by volume of HNO.sub.3 in 500 l/h of nitrogen (technical
grade) at 140.degree. C. for 10 h. Weight loss: 22.1%. Thereafter,
bead-like outgrowths were observed on the surface, which were
assumed to have been formed by the reaction of Mg with
HNO.sub.3.
[0056] Thereafter, thermal debinding was carried out at a
temperature of up to 420.degree. C. in pure nitrogen within 1 hour,
as described in Example 3, again followed by sintering for 1 h at
an oven temperature set to 665.degree. C.
Results
[0057] Length shrinkage: 10.7% [0058] Shrinkage of the bars'
diameter: 14.65% [0059] Sintered density: 2.36 g/cm.sup.3
Example 5
Tensile Test Bars: Catalytic/Thermal Debinding
TABLE-US-00005 [0060] Feedstock component Percentage (% by weight)
Aluminum powder 70.1 Magnesium powder 2.2 POM binder 24.0
Surfactant* 3.7 100.0 *ethoxylated C.sub.13-C.sub.15-oxoalcohol
having 7 EO-units
Debinding, and Sintering of the Tensile Test Bars
[0061] At first, catalytic defending according to Example 4 was
carried out at 140.degree. C. for 24 h, using 80 g anhydrous oxalic
acid on a sublimation dish instead of HNO.sub.3. Weight loss: 23.0%
. When using oxalic acid, there were no outgrowths appearing on the
surface. Thereafter, thermal debinding and sintering were also
carried out according to Example 4.
Results
[0062] Length shrinkage: 14.28% [0063] Shrinkage of the bars'
diameter: 15.68% [0064] Sintered density: 2.42 g/cm.sup.3
Example 6
Tensile Test Bars: Catalytic/Thermal Debinding
TABLE-US-00006 [0065] Feedstock component Percentage (% by weight)
Alumix 231 powder* 70.8 POM binder* 25.6 Surfactant** 3.6 100.0
*commercially available metal powder mixture of aluminum and 14% by
weight of silicon, 2.5% by weight of copper, and 0.6% by weight of
magnesium (from Ecka) **ethoxylated C.sub.13-C.sub.15-oxoalcohol
having 7 EO-units
Debinding and Sintering of the Tensile Test Bars
[0066] At first, catalytic debinding was carried out according to
Example 5. Weight loss: 25.2%. Thereafter, thermal debinding and
sintering were carried out according to Example 4, applying an oven
temperature set to 560.degree. C.
Results
[0067] Length shrinkage: 11.2% [0068] Shrinkage of the bars'
diameter: 13.2% [0069] Sintered density: 2.45 g/cm.sup.3
Example 7
Tensile Test Bars: Catalytic/Thermal Debinding
TABLE-US-00007 [0070] Feedstock component Percentage (% by weight)
Aluminum powder 68.0 Master alloy powder* 4.3 POM binder 24.0
Surfactant** 3.7 100.0 *master alloy consisting of 50/50 aluminum
and magnesium **ethoxylated C.sub.13-C.sub.15-oxoalcohol having 7
EO-units
Defending and Sintering of the Tensile Test Bars
[0071] At first, catalytic defending was carried out according to
Example 5. Weight loss: 23.2% . Thereafter, thermal defending and
sintering were carried out according to Example 4.
Results
[0072] Length shrinkage: 12.6% [0073] Shrinkage of the bars'
diameter: 13.25% [0074] Sintered density: 2.56 g/cm3
Example 8
Hollow Cylinders: Catalytic/Thermal Debinding
TABLE-US-00008 [0075] Feedstock component Percentage (% by weight)
Aluminum powder 68.0 Master alloy powder* 4.3 POM binder 24.0
Surfactant** 3.7 100.0 *master alloy consisting of 50/50 aluminum
and magnesium **ethoxylated C.sub.13-C.sub.15-oxoalcohol having 7
EO-units
Debinding and Sintering of the Hollow Cylinders
[0076] At first, thermal debinding was carried out according to
Example 5. Weight loss: 23.7%. Thereafter, thermal debinding and
sintering were carried out according to Example 4.
Results
[0077] Height shrinkage: 17.24% [0078] Diameter shrinkage: 14.48%
[0079] Sintered density: 2.59 g/cm.sup.3
Example 9
Tensile Test Bars: Catalytic/Thermal Debinding
TABLE-US-00009 [0080] Feedstock component Percentage (% by weight)
Aluminum powder 67.1 Master alloy powder* 4.3 POM binder* 25.8
Lucryl G55** 2.8 100.0 *master alloy consisting of 50/50 aluminum
and magnesium **commercially available poly(methylmethacrylate)
(PMMA; from BASF)
Debinding and Sintering of the Tensile Test Bars
[0081] At first, catalytic debinding was earned out according to
Example 5. Weight loss: 25.7% . Thereafter, thermal debinding and
sintering were carried out according to Example 4.
Results
[0082] Length shrinkage: 13.57% [0083] Shrinkage of the bars'
diameter: 19.55% [0084] Sintered density: 2.59 g/cm.sup.3
Example 10
Hollow Cylinders: Catalytic/Thermal Debinding
TABLE-US-00010 [0085] Feedstock component Percentage (% by weight)
Aluminum powder 67.1 Master alloy powder* 4.3 POM binder 25.8
Lucryl G55** 2.8 100.0 *master alloy consisting of 50/50 aluminum
and magnesium **commercially available poly(methylmethacrylate)
PMMA; from BASF)
Debinding and Sintering of the Hollow Cylinders
[0086] At first, catalytic debinding was carried out according to
Example 5. Weight loss: 25.6%. Thereafter, thermal debinding and
sintering were carried out according to Example 4.
Results
[0087] Height shrinkage: 16.52% [0088] Diameter shrinkage: 14.48%
[0089] Sintered density: 2.56 g/cm.sup.3
[0090] The method of the invention is thus capable of providing
sintered bodies of aluminum alloys by injection molding, which are
suitable for practical applications in different fields, including
the fields of transport, construction, mechanical engineering,
packaging industry, iron and steel industries, electronic
engineering, household appliances, etc., for example for
dissipating heat as heat sinks in electronic devices, or as
components of air conditioning systems.
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