U.S. patent application number 10/540459 was filed with the patent office on 2006-04-06 for component produced or processed by powder metallurgy, and process for producing.
Invention is credited to Alexander Bohm, Dirk Naumann, Thomas Weissgarber.
Application Number | 20060073062 10/540459 |
Document ID | / |
Family ID | 32519968 |
Filed Date | 2006-04-06 |
United States Patent
Application |
20060073062 |
Kind Code |
A1 |
Naumann; Dirk ; et
al. |
April 6, 2006 |
Component produced or processed by powder metallurgy, and process
for producing
Abstract
The invention relates to components which are produced or
processed by powder metallurgy, and to processes for producing
components of this type. The components produced by powder
metallurgy are intended both to have porous regions and to provide
fluid-light properties, and it should also be possible to produce
them at correspondingly low cost and suitably flexibly. For this
purpose, a component of this type has at least one porous region,
which is formed from an intermetallic phase or solid solutions.
However, it may also have a corresponding surface coating.
Moreover, in a component of this type there is at least one areal
fluid-tight region which is formed from a metal or metal alloy of
the corresponding intermetallic phase or solid solution.
Inventors: |
Naumann; Dirk; (Ontario,
CA) ; Weissgarber; Thomas; (Dresden, DE) ;
Bohm; Alexander; (Hahnichen, DE) |
Correspondence
Address: |
INCO PATENTS & LICENSING
PARK 80 WEST - PLAZA TWO
SADDLE BROOK
NJ
07663
US
|
Family ID: |
32519968 |
Appl. No.: |
10/540459 |
Filed: |
December 17, 2003 |
PCT Filed: |
December 17, 2003 |
PCT NO: |
PCT/EP03/14381 |
371 Date: |
June 22, 2005 |
Current U.S.
Class: |
419/2 |
Current CPC
Class: |
B22F 7/004 20130101;
B22F 2998/00 20130101; B22F 7/064 20130101; B22F 2999/00 20130101;
B22F 2999/00 20130101; B22F 2999/00 20130101; B22F 2998/00
20130101; B22F 2998/10 20130101; B22F 2998/10 20130101; B22F
2999/00 20130101; B22F 1/0003 20130101; B22F 3/1109 20130101; B22F
1/0003 20130101; B22F 2998/10 20130101; B22F 7/004 20130101; B22F
3/1275 20130101; B22F 7/004 20130101; B22F 3/23 20130101; B22F
3/1039 20130101; B22F 9/04 20130101; B22F 7/004 20130101; B22F
2203/05 20130101; B22F 3/114 20130101; B22F 9/04 20130101; B22F
3/004 20130101; B22F 3/23 20130101 |
Class at
Publication: |
419/002 |
International
Class: |
B22F 3/11 20060101
B22F003/11 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 8, 2003 |
DE |
103011757 |
Claims
1. A component which is produced or processed by powder metallurgy
and has at least one porous region, which is formed from an
intermetallic phase or solid solutions or has a surface coating of
this type, and at least one areal fluid-tight region, which is
formed from a metal, a metal alloy, and the corresponding
intermatallic phase or solid solution.
2. The component as claimed in claim 1, wherein the fluid-tight
region forms part of the outer shell of the component.
3. The component as claimed in claim 1, wherein the fluid-tight
region is surrounded by the porous region.
4. The component as claimed in, claim 1 wherein the corresponding
intermetallic phase or the solid solutions are selected from at
least one of the four consisting of nickel, aluminum, molybdenum,
tungsten, iron, titanium, cobalt, copper, silicon, cerium,
tantalum, niobium, tin, zinc and bismuth.
5. The component as claimed in, claim 1 wherein at least the porous
region is formed from nickel aluminide or is coated therewith.
6. The component as claimed in, claim 1 wherein at least the porous
region has a porosity and density which change in steps or
gradually in the direction of the areal fluid-tight region.
7. The component as claimed in, claim 1 wherein at least the porous
region is formed from a metal or metal alloy of the corresponding
intermetallic phase or solid solution.
8. The component as claimed in, claim 1 wherein at least one
passage or aperture is formed in the areal fluid-tight region.
9. The component as claimed in, claim 1 wherein the areal,
fluid-tight region has a density of over 96% of the theoretical
density.
10. A process for producing a component which is produced or
processed by powder metallurgy and has at least one porous region,
which is formed from an intermetallic phase or solid solutions or
has a surface coating of this type, and at least one areal
fluid-tight region, which is formed from a metal, a metal alloy,
and the corresponding intermetallic phase or solid solution wherein
a starting powder which has a sintering activity and forms
intermetallic phases or solid solutions is used to form the areal
fluid-tight region.
11. The process as claimed in claim 10 wherein a starting powder
with a grain size d.sub.50<50 .mu.m and a powder with a
sintering activity obtained by high-energy milling are used for
production.
12. The process as claimed in claim 11 wherein a powder perform is
produced from differentiated starting powders, the dimensions of
which perform take account of the different shrinkages of the
differentiated starting powders during sintering.
13. A process for producing a component which is produced or
processed by powder metallurgy and has at least one porous region,
which is formed from an intermetallic phase or solid solutions or
has a surface coating of this type, and at least one areal
fluid-tight region, which is formed from a metal, a metal alloy,
and the corresponding intermetallic phase or solid solution wherein
a porous structure, which forms the porous region, is coated with a
powder which has a sintering activity and forms intermetallic
phases or solid solutions, and the areal fluid-tight region is
formed at a surface of the component by a subsequent sintering
operation.
14. A process for producing a component which is produced or
processed by powder metallurgy and has at least one porous region,
which is formed from an intermetallic phase or solid solutions or
has a surface coating of this type, and at least one areal
fluid-tight region, which is formed from a metal, a metal alloy,
and the corresponding intermetallic phase or solid solution wherein
a metallic, areal and fluid-tight element, which forms the
fluid-tight region, is coated with a layer of a powder which
contains at least one element of the intermetallic phase or solid
solution, and the fluid-tight region is joined to a porous
structure, which has been placed on top of the powder layer and
forms the porous region, by sintering.
Description
[0001] The invention relates to components which are produced by
powder metallurgy or alternatively are processed by powder
metallurgy and have at least one porous region, which is formed
from an intermetallic phase or solid solutions, or have a surface
coating of this type. In addition, the invention also relates to
corresponding production processes. In this context, the term
processing by powder metallurgy is to be understood as meaning a
corresponding, retrospective processing of semifinished products,
such as for example metal foam structures, by powder
metallurgy.
[0002] The prior art has disclosed possible ways of producing
sintered porous bodies which have been formed from intermetallic
phases or solid solutions. A process of this type is described, for
example, in DE 101 50 948. In this document, it is proposed for a
powder with a sintering activity which at least forms intermetallic
phases or solid solutions to be applied to the surface of a porous
base body. Then, the formation of intermetallic phases or solid
solutions is supposed to be initiated by means of a heat treatment.
At the same time, the surface area can thereby be increased.
[0003] Although the bodies produced in this way have a relatively
low inherent mass and also, if suitable intermetallic phases or
solid solutions are selected, a high thermal stability, they cannot
readily be used for some applications. This is true in particular
with regard to use as a sealing element without additional assembly
or connection to components which are impervious to the various
fluids.
[0004] Therefore, it is an object of the invention to provide
components which are produced by powder metallurgy and have both
porous regions and fluid-tight properties and which can also be
produced flexibly and at low cost.
[0005] According to the invention, this object is achieved by
components which have the features of claim 1. Advantageous
production processes result in accordance with claims 10, 13 and
14. Advantageous configurations and refinements of the invention
can be achieved by the features listed in the subclaims.
[0006] The component according to the invention which is produced
by powder metallurgy or is additionally processed in this way
accordingly includes at least one porous region, which is formed
from an intermetallic phase or solid solutions. However, a porous
region of this type may also be provided with a corresponding
surface coating which is formed from an intermetallic phase or
solid solutions of this type.
[0007] Furthermore, there is at least one areal fluid-tight region
which is formed from a metal, a metal alloy of the corresponding
intermetallic phase or the corresponding solid solution.
[0008] The term fluid-tight is to be understood as meaning at least
imperviousness to certain liquids, but also, under certain
circumstances, gas-tightness and even imperviousness to
low-molecular gases or gases with a low atomic number.
[0009] In an advantageous configuration, the fluid-tight region may
form part of the outer shell of the component, which the
correspondingly porous region may then adjoin in one direction.
[0010] However, it is also possible for a fluid-tight region of
this type to be surrounded by the porous region. In this case, the
fluid-tight region may form a type of core or alternatively a
barrier within a component.
[0011] Nickel, aluminum molybdenum tungsten, iron, titaniunm
cobalt, copper, silicon, cerium tantalum niobium, tin, zinc or
bismuth can be used to form the intermetallic phases or solid
solutions. It has proven particularly advantageous for at least the
porous region to be made from nickel aluminide or to use a
corresponding surface coating made from nickel aluminide, since
this also makes it possible to achieve very good thermal
stabilities.
[0012] However, the porous region may advantageously also be formed
in such a way that a porosity changes in the direction of the
areal, fluid-tight region. This may be effected in steps, i.e. in
layers with different porosities within the individual layers, or a
continuously graduated form
[0013] The fluid-tight region should advantageously have a density
which is over 96% of the corresponding theoretical density.
[0014] In one embodiment, however, the fluid-tight region may be
formed from a pure metal or a metal alloy of the corresponding
intermetallic phases or of a solid solution which is formed
areally, for example in the form of a plate. For example, a porous
region can be arranged on a nickel component which is, for example,
of plate-like design and a porous region, which either consists of
nickel aluminide or is surface-coated with nickel aluminide, can be
joined by material-to-material bonding to it, as described in more
detail below.
[0015] Furthermore, it is possible for at least one passage or an
aperture to be formed within the fluid-tight region. A passage can
be used, for example, for liquid or gaseous coolant to pass
through. However, it is also possible to use a passage of this type
and adjoining openings to generate a reduced pressure all the way
into the porous region, so that a sucking or vacuum action can be
achieved in that region.
[0016] However, apertures can also be used to secure a component
according to the invention using mechanical means.
[0017] There are a number of alternative options for producing
and/or coating components according to the invention.
[0018] For example, to produce components of this type, it may be
expedient to use different starting powders. In this case, a
starting powder which has a sintering activity and forms
intermetallic phases or solid solutions should be used at least to
form an areal, fluid-tight region. This makes it possible to make
use of the effect whereby an increase in volume is observed during
sintering, causing sufficiently dense sintering of the
corresponding region, so that the required fluid-tightness can be
achieved.
[0019] Starting powders with a mean grain size d.sub.50<50 .mu.m
should be used in particular to form the porous region during
sintering, it being possible, for example, to form the stepped or
graduated porous regions which have already been mentioned above to
be formed by means of a suitable selection of different grain size
fractions.
[0020] However, it is also possible, in order to produce components
according to the invention, to produce starting powders of the
abovementioned grain size fraction in combination with a powder
which has a sintering activity and is obtained by high-energy
milling.
[0021] For example, a porous region may be formed exclusively from
a starting powder of this type, while an adjoining region, which is
likewise porous, may be formed by means of a mixture of this
starting powder with a powder which has a sintering activity and is
obtained by high-energy milling, and for a fluid-tight region then
to be formed exclusively by means of a starting powder which has a
sintering activity and is obtained by high-energy milling.
[0022] These different powders employed have different properties
during the sintering. In this context, in particular the differing
shrinkage is of importance.
[0023] For example, a powder preform which has been prepared for
the powder metallurgy production of components according to the
invention may have locally differing dimensions which take account
of the different starting powders and their shrinkages which are
observed during sintering, so that after sintering a component
which is at least near net shape can be provided, requiring at most
only slight remachining.
[0024] During production of a powder preform of this type, by way
of example regions in which the powder preform contains starting
powders with a higher sintering activity, such as for example
powder mixtures obtained by high-energy milling, or have been
formed in such regions exclusively from powders of this type with
corresponding binders, are characterized by higher shrinkages,
which have to be taken into account accordingly.
[0025] In another alternative, however, it is also possible for
components according to the invention to be produced in such a way
that a porous structure which is to form the porous region has
already been areally coated with a powder which has a sintering
activity and forms intermetallic phases or solid solutions. Then,
the coated region can be formed in a fluid-tight manner on the
corresponding surface of the components by means of a sintering
operation.
[0026] In this case, by way of example, it is possible to use a
porous starting structure such as a semifinished product,
comprising a corresponding intermetallic phase or a solid
solution.
[0027] However, it is also possible for a porous structure,
likewise in the form of a semifinished product, such as a metal
foam preferably a nickel foam, to be surface-coated with a powder
which forms intermetallic phases or solid solutions, as is known
from DE 101 50 948, and for an areal layer then additionally to be
formed on a surface from a powder which has a sintering activity
and forms intermetallic phases or solid solutions and which then
likewise forms the fluid-tight region during sintering. For
example, the porous structure, i.e. the porous region of a
component according to the invention, can be correspondingly
modified and the fluid-tight region formed in a sintering
operation.
[0028] A further alternative production option consists in a
metallic element, which is areal and fluid-tight at least in
regions and is to form the fluid-tight region, to be joined to a
porous structure, which then forms the porous region, by
material-to-material bonding. This can be achieved by means of a
sintering operation in which the metallic areal element is coated
beforehand with a layer of a powder which contains at least one
element of the intermetallic phase or of the corresponding solid
solution and forms a material-to-material bond with this powder
during sintering. The metallic areal element may likewise be formed
from an element of the corresponding intermetallic phase or solid
solution or from an alloy of this element.
[0029] The invention is to be described below by way of
example.
EXAMPLE 1
[0030] A starting powder mixture which contains nickel and aluminum
was used to produce an example of a component according to the
invention. The grain size fraction was in the range between 5 and
30 .mu.m
[0031] A nickel to aluminum atomic ratio of 50/50 atomic % was
maintained for the mixture composition. The nickel and aluminum
starting powders were mixed with one another for a period of 0.5 h.
This mixture Ml was then divided into two partial quantities. One
of these partial quantities was subjected to high-energy milling in
a Fritsch P5 planetary ball mill at a rotational speed of 250 min/h
for a period of 1 h. This resulted in a part mixture M. In turn, a
third part mixture M3 was produced from the mixture M1 and the
mixture M2, containing these two mixtures in equal parts.
[0032] Components were compacted from these mixtures in advance by
die-pressing in the following order: mixture M1, mixture M2 and
mixture M3.
[0033] Then, a reaction sintering operation was carried out in
vacuo at a temperature in the region of 1150.degree. C., and a
component according to the invention which has three different
porous regions was produced. That part of the component which was
formed from powder mixture M3 forms the fluid-tight region, whereas
the regions formed from mixtures M1 and M2 had a significantly
higher porosity.
[0034] It was possible to use the powder mixtures with conventional
binders which are known per se and are removed during sintering.
The grain sizes of the different starting powders M1 to M3 were
kept virtually constant, and accordingly in this example there is
no grain size change in the high-energy milling process, only the
sintering activity of the powder having been changed.
EXAMPLE 2
[0035] A nickel foam structure is surface-coated with a pure
aluminum powder or a nickel-aluminum powder obtained by high-energy
milling. A nickel/aluminum atomic ratio in the range between 75 to
50 atomic % of nickel to 25 to 50 atomic % of aluminum was
maintained. The coating with a powder of this type was carried out
in such a way that an open porosity of the nickel foam was
retained. The nickel foam body prepared in this way was then coated
on one side with a powder M3 as described in Example 1, after which
sintering was again carried out at a temperature of approx.
1150.degree. C. The corresponding intermetallic phases were formed
on the surface of the nickel foam, and a fluid-type region
comprising nickel aluminide was formed where the powder M3 was
additionally applied.
* * * * *