Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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B_CKGROUND OF THE_INVENTION
The invention relates to a self-supporting, dimensionally
stab1e carbon composite member of a plurality of carbon
- layers joined together as well as to a method of producing
it.
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DESCRIPTION OF lHE PRIOR ART
Self-supporting carbon composite members are known.
They consist of a plurality of carbon felt layers
stacked one onto the other, which are prior to curing
(hardening) and coking adhesive1y joined spotwise ~ith
a carbonaceous cement. The dimensional stability of
such composite members leaves, however, to be desired.
In another known carbon composite member, a plurality
of carbon felt layers are coated on their outer surfaces
with a binder, which serves to adhesively join together
the individual layers. In that connection, the binder
at least partly penetrates into the free pore space of
the felt, so that the adjacent pores on the surface are
at least partly filled with binder, while the pores
disposed further within are provided with correspondingly
less filling. The carbon felt layers, hence, are not
impregnated with the binder uniformly, so that there is
provided an inhomogeneous distribution in the carbon
felt member which involves drawbacks particularly in
cases, in which importance is attached to a good thermal
insulation.
Furthermore, there is known a carbon member of high
porosity, low gross or green density and heat conductivity,
which consists of single-layer or multi-layer carbon or
graphite felt that has been impregnated with a carbonaceous
binder and has been subsequently coked or, respectively,
graphitized through the action of pressure and heat,
and which exhibits a relatively low green or gross density
and a high dimensional stability, with a part of the binder
having been removed prior to coking or, respectively,
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graphitization from the fe~t by means of having been
pressed-off, rolled-off or ~he like. This carbon member
involves the advantage that it is dimensionally stable
and has a relatively low density and hea-t conductivity
' and, moreover, can be produced with large dimension, -the
porosity that is present throughout in these products,
however is in many cases undesirable.
SUMMARY OF THE PRESENT INVENTION
In accordance with one aspect of one embodiment,
the present invention can provide the self-supporting
carbon composite member of the type as mentioned such
that it meets extrerne requirements parti~ularly
concerning its dimenslonal stabi~ity, thermal insula-tion
and electrical properties, such as they occur on the
field of high-temperature technique, for example nuclear
reactor operation, and oE electrochemistry as well as in
the construction of high-temperature power plants
(transmissions).
Another aspect of another embodiment of the present
invention provides a carbon composite member in which
the gas permeability should be purposively adjustable.
According to yet another aspect of another
embodiment of the presen-t inven-tion there may be
provided a method for manufacturing such a carbon member
in an economical way.
According to a feature of one embodiment of the
present invention there is provided a self supporting,
dimensionally stable carbon composite member of a
plurality of carbon layers bonded together, comprising
one or more layers of carbon felts and one or more thin,
sheet-like shaped carbon members, adhesively joined to
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the former, the members consisting of granular or, respectively,
pulverulent and/or fibrous carbon particles as fillers and of a
coked binder, the carbon members being cons-tructed of 3 rolled
plastic carbon composition with a binder proportion of from 50 to
150~ by weight, based on the filler material, and the carbon
members, the carbon felt layers and the binder being thermally
joined together with the binder arranged between the carbon felts
and the carbon members and coked to adhesively join the carbon
members ~nd carbon felt layers together.
According to another feature of one embodiment of the
present invention there is provided a self-supporting,
dimensionally stable carbon composite member of a plurality of
carbon layers joined together, comprising one or more layers of
carbon ~elts and one or more thin, sheet-like shaped carbon
members, adhesively attached to the former and consisting of
granular or, respectively, pulverulent and/or fibrous carbon
particles as fi:ller materials and a coked binder, each of -the
carbon members being formed from a green member of a plastic
carbon composition having a binder content of from 50 to 150% by
weight, based on the filler material, which composition has been
subjected to shearing forces in forming the thin sheet-like
shaped carbon member; and assembled with one or more oE the
layers of carbon felts; and the carbon members and the layers of
carbon felts being thermally treated so that the binder in the
carbon member is coked and the carbon members and the carbon felt
layers are joined together.
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DETAILED DESCR~PTION OF THE PRESENT INVENTION
The carbon composite member according to the invention
cQnsequently is put together of substantially plane-
parallel layers of carbon felts layered one onto the
other and of at least one plate-shaped carbon member of
a special type, which is designated as thin and sheet-
like, and which in the case of an embodiment of the
invention, in which only a single felt layer is utilized,
covers the two surfaces of said felt layer.
The plate-shaped carbon member of the special kind
consists of a mixture of granular or, respectively,
pulverulant and/or fibrous carbon particles as filler
materials, such as coke3 carbon black, natural or
synthetic graphite or the mixtures thereof, as well as
of a carbonaceous bincler, for which, according to a
further embodiment of the invention, phenol formaldehyd
resin, furan resin, tar, pitch or other mixtures have
proved particularly serviceable. The binder content
amounts to from 50 to 150% by weight, based on the
filler material, and hence is comparatively high.
This polygranular carbon member becomes the carbon
member as a part of said composite member in that a
plastically deformable carbon composition (mass) is
produced from granular or, respectively, pulverulant
and/or fibrous carbon particles as filler materials and
from a carbonaceous binder, which composition is rolled
out to a film-like plate in a roller gap (nip), which is
defined by unheated rollers, under the influence of
shearing forces at room temperature, i.e. about 18C.
There now are two possibilities for the further course
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followed in production. Firstly, the plate rolled out in this
manner can be subjected to a thermal treatment to coke the
binder, and at least one carbon felt layer can be placed
either individually or in plural number onto the thus provided
film or sheet-like plate that is resistant to bending and
stable in shape, said carbon felt layer being inseparably
joined through adhesive attachment to the plate or plates.
According to an alternative prosecution of the process, the
thin structure of plastic carbon composition rolled out in the
manner of a film can at first be assembled with the carbon
felt layer or layers and thereafter be subjected to the
thermal treatment as a composite member. In this case, too,
an inseparable connection between the carbon felt layer or
layers and the sheet-like carbon material is attained, the
binder that is in the carbon material serving as adhesive, but
additional binder may also still be applied onto the surfaces
to be adhesively joined prior to the thermal treatment.
The layer-like or sandwich-like structure of the carbon
composite member according to the invention, in which
the individual layers consist of the characterized,
different carbon materials, form a thermal insulation
member of excellent insulation properties, which are
to be traced back to the fact that the carbon felt layers,
due to their pore volume, act as good heat conduction
barriers, and the sheet-like carbon members disposed there-
between distribute, despite the insulation effect of the
carbon felt layers, heat passing through them uniformly
over the entire surface area of the next following layer
in that they ensure a rapid lateral aissipation of the heat
passin~ through. In this manner, so-called "hot-spots",
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hence, spots of extensive overheating on account of heat
concentrations are avoided in a high temperature insulation,
which consists of that kind of a carbon composite member
material.
Furthermore, the sheet-like carbon member also serves
on or between the carbon felt layers as gas passage
barrier; hence, considerable advantages are attained
by the carbon composite member described here in cases,
in which not only a good thermal insulation is to be
attained but, rather, a gas passage therethrough is to
be avoided and the oxidation of the felt material caused
under certain circumstances thereby, with the consequence
that the insulation properties thereof are impaired.
The carbon composite member may have a plate-shaped
configuration, but it may also be bent in ring-shaped
manner, or it may be in the form of a tube, viz. in
adaptation to the respective purpose of use. According
to an advantageous embodiment of the invention, the
carbon felt layers have been made dimensionally stable
prior to assembly with the thin, sheet-like carbon
member or members through partial impregnation with a
carbonaceous binder and subsequent temperature treat-
ment, with the above-mentioned binders also being able
to be used in this case. The partial impregnation, in
which a portion of the impregnation agent is removed
from the felt again, for example by squeezing-off said
felt, so that the density thereof diminishes, is a
means for adjusting the heat conductivity of the felt
and, hence, of the entire carbon composite member.
There further is the possibility that the binder content
of the plastic carbon composition (mass), of which the
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thin, sheet-like shaped carbon member has been produced7
amounts to about 100% by weight, based on the filler
material. The carbon residue remaining after carbonization
of the binder in the polygranular carbon member is at
about 35 to 70% by weight.
There are used for the thin, sheet-like carbon ~ember
as a part of tne carbon composite member according to
the invention filler materials of a granular or,
respectively, pulverulant and/or fibrous and/or flaky
kind, for example cokes, carbon blacks, natural or
synthetic graphites, carbon fibers or the mixtures thereof.
The thickness of the thin, sheet-1ike carbon member is
usefully between 0.1 and 2.0 mm, and values of 20:1
to l:l have proved particularly advantageous for the
ratio oF the thickness of the carbon felt layers to the
thickness of the sheet-like carbon members, which means
that as a rule the felt layers have a greater thickness
than the material layer which is formed by the shaped
carbon member.
Methods are known for producing the carbon felts, vi~.
also the partially impregnated ones.
It is to be understood that a wide variety of plate-
shaped carbon composite members is possible with the
aid of the two above mentioned methods for producing
the carbon composite members and the;r variat;ons, inso-
far as the number of the individual layers, their
arrangement within the composite member, hence, their
position relative to one another and their thickness is
concerned, and that it is also possible to produce
actually any desired carbon composite member configurations
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through compression molding in compression molds
within special pressing tools, which correspond to the
configuration of the shaped article to be produced, or
in veneer presses. For example, a plate-shaped carbon
composite member can be deformed into arched areal
members in the rude or "green" state, hence, when it
still can be to a certain extent plastically deformed
because the carbonaceous binder has not yet been
temperature treated and thus not been hardened, said
parts retaining the shaped configuration after said
temperature treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings diagrammatically show a few
exemplary embodiments of the carbon composite member
according to the invention.
Figure 1 illustrates a perspective view of an
insulation element;
Figure 2 illustrates a perspective view of a part
of the carbon composite member curved;
Figure 3 is an illustration in perspective of a
single layer tubular hollow member;
Figure 4 illustrates a perspective view of a part
of a carbon composite member made up of five layers;
Figure 5 illustrates a perspective view of a
multi~layer insulation member; and
Figure 6 illustrates a plan view of a hollow
member.
DESCRIPTION OF THE DRAWINGS
Figure 1 shows a perspective view of an
insulation element consisting of a carbon felt layer 3
with plane-parallel shaped carbon members 1 and 2
adhesively attached on either side.
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Flgure 2 shows a perspective view of a part of
the carbon composite member curved in cup-shaped
manner, which could likewise serve for insulation
purposes, and which consists, as in the case of the
embodiment of Figure 1, of a center carbon felt layer
6 having a thickness of about 10 mm and of two shaped
carbon member layers 4 and 5 adhesively attached to
either sid~, whose thickness is about 1 mm.
Figure 3 is an illustration in perspective of a
single layer tubular hollow member 7, which is formed
of a sheet-like shaped carbon member, hence, has no
carbon felt layer and insofar as that is concerned
does not constitute any laminate but, rather, only the
outer or the inner sheath of such a laminate.
Figure 4 shows a perspective view o~ a part of a
carbon composite member made up of five layers, which
is utilized for example for high temperature purposes
and consists of three felt layers 8, 9, 10 and of two
shaped carbon member layers 11, 12, which are embedded
between said Eelt layers, to which they are adhesively
attached. That kind of plate-shaped composite members
can be produced depending upon the technical
possibilities of production so as to have any desired
sizes, for example also in the form of relatively
large plates of an edge length of 700 x 2000 mm.
The forms shown in ~igures 5 and 6 show further
examples in respect of the many and varied
possibilities o desiyn and, hence, also use ofEered
by the car~on composite member according to the
invention.
Figure 5 shows a perspective view oE a multi-
layer insulation member having stepped outer edges.
In this case, two plane-parallel carbon felt layers
13, 14 are separàted by a thin, sheet-like shaped
carbon me~ber 16 and are covered on their top side as
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well as on their underside by like, dimensionally
stable shaped carbon members 15 and 17 in a manner
such that said shaped members at the left side project
beyond the edges of the felt layers by a distance
corresponding to the width of the uncovered felt layer
surfases 18, 19 on the right side of the composite
member. The material layers or plies 13, 14, 15, 16,
17 that are adhesively joined together in this way
form a groove and tongue member, which can be
assembled with members of like kind by means of
putting them together to form larger surface area
structures, without this requiring any particular
elements of connection.
The embodiment of a carbon composite member shown
in Figure 6 illustrates a plan view of a hollow member
assembled of four plate-shaped composite members 20 to
form a rectangular tube, the inner cavity of which
hollow member is designated by 22. The sheet-like
carbon members 25 covering the felt layer 21 on either
side are produced on one side at 23 on the exterior of
each composite member 20 so as to thereby cover the
front end of the next composite member arranged to
follow at right angles, while part of the surface on
the inner side of each composite member, as shown at
24, is not covered by the sheet-like carbon members,
the width of which part corresponds to the front end
of the further composite member that is contiguous at
right angles. In this manner, a rectangular tube
results, whose exterior and interior sides are
entirely covered by the sheet-like carbon members, so
that no heat bridges form at the four junctions of the
four composite members.
