Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to the use of elements made of
fibre-reinforced or fibre-bundle-reinforced composite
materials with ceramic matrix for partial or complete
absorption of at least one impact-like load focussed at
a point, in particular as structural components.
In the following and in the claims, both individual
-. fibres and the fibre bundles used for the most part,
which compared with individual fibres can have a
substantially greater width and also height, are
referred to together under the term "fibres".
Fibre-reinforced composite materials with ceramic
matrix have been known for a long time and are in
general distinguished by a high strength and rigidity
with simultaneously low weight. These properties are
maintained even up to high temperatures. The fibre-
reinforced composite materials have a high thermal
conductivity and at the same time a low thermal
,,~, expansion and thus an excellent resistance to thermal
shocks.
Starting from carbon-fibre-reinforced composite
materials with carbon matrix (CFC), composite materials
with SiC as a matrix have been developed to an
increasing extent over the last ten years, with carbon
fibres (C/SiC) and silicon carbide fibres (SiC/SiC)
being used as reinforcing fibres.
A silicon carbide body reinforced with short graphite
fibres, which body has a quasi-ductile breaking
behaviour, is known from DE 197 10 105 A1. The
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reinforcing short graphite fibres are surrounded by at
least one shell of graphitised carbon obtained by
impregnation with carbonisable impregnating agents and
subsequent carbonisation. The shell of the fibres is
partly converted into silicon carbide during the
production of the C/SiC composite material. To that
end, the composite body is infiltrated with liquid
silicon, wherin the at least partial conversion of the
carbon matrix of the carbonised initial product into
silicon carbide also takes place.
In the discussion of this prior art, lining materials
for reusable space missiles, nozzle linings of jet
engines, turbine blades or even friction linings are
generally spoken of as possibilities of use for
composite materials. The composite materials described
in DE-A-197 10 105 can be used as portions of gas
turbines, as components of burners and nozzles, as hot-
gas pipes, or even as friction materials for high
loads, such as linings for brakes.
A process for producing fibre-reinforced composite
ceramics with high temperature fibres which are
,.-. reaction-bonded with a matrix based on silicon and
silicon carbide or a silicon alloy, as described in DE
41 27 693 A1, for example, is known from DE 197 11 829
C1. Composite bodies of this type are used for the
production of mass-produced components, such as brake
discs.
The use of ceramics as an armour plating system,
because of their light weights, is also known.
Ceramics are generally distinguished by high rigidity
and hardness. In the case of the use for armour
plating, it is essential that the ceramics can
withstand a plastic deformation under high load. A
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high tensile strength is required particularly on the
rear surface of an armour plate. For this reason,
therefore, a typical armour plating in which a ceramic
composite is used consists of a ceramic front side
which is provided, on its rear side, with a fibrous
composite or metal substrate as reinforcement
(backing). Usually, these different materials are
connected to each other by gluing. Glass, glass-
ceramics, or technical ceramics such as oxides, borides
or even carbides are used as the ceramic material. In
particular, aluminium oxide has distinguished itself
~'" because it is also relatively favourable in terms of
cost. The ability to withstand a plastic deformation,
however, is not particularly satisfactory in ceramics.
Because ceramics display a brittle breaking behaviour,
a loading of the ceramic material focussed on a point,
for example by a projectile, leads to a continuous
cracking in the ceramic material. The ceramic material
is therefore destroyed over a large area and thus loses
its protective effect. Heretofore, this problem could
be remedied only by mounting on a backing small ceramic
segments having a maximum extent of 3 cm for a very
high protection (safety for cars) and l0 cm for a
,~~~, simple, for example military, protection in the plane
perpendicular to the action of the point-focal load.
Thus, if a projectile impacts, always only one ceramic
segment is ever destroyed. The production of a
composite made up of such ceramic segments is, however,
very costly. However, ceramics alone have not hitherto
been able to be used as a large-surface protective
element.
When an armour plate is hit by a projectile, in the
case of a conventional ceramic material, a breakage of
the ceramic plate itself results because of reflection
of the stress waves within the ceramic plate. Only
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because a further rear side, for example made of metal,
is mounted behind the ceramic plate, that it is
possible to prevent the projectile from completely
penetrating this armour plate.
In the case of the use for armour plates, it is
necessary for the ceramic material to have a clearly
greater hardness than the material of the projectile,
which usually has a Vicker s hardness of approximately
6.5 to 8.0 kN/mm2. It would therefore be favourable to
use materials having a hardness of more than
"""~ approximately 9.8 kN/mm~. If the ceramic material is
too soft, the projectile core penetrates through the
ceramic material, because it is not damaged or
flattened by the ceramic material.
However, there is also ammunition with clearly greater
hardness, particularly if ammunition having a core of
tungsten carbide in a nickel-iron matrix is used. In
such a case, the hardness can rise to approximately 11
kN/mmZ, for example.
A ceramic material made of highly pure aluminium oxide
r~ could withstand such a projectile because it has a
hardness of more than approximately 16.6 kN/mmZ. It is
likewise possible to use other ceramic materials, for
example silicon carbide, already mentioned above, boron
carbide, or even titanium diboride, the hardness of
which is clearly greater.
It is likewise known to use zirconia-reinforced
aluminium oxide, or titanium borides. However, a hot-
press process has to be used during production in order
to obtain the optimal properties. In order to do this,
the powders from the respective starting material are
compacted and heated in a graphite nozzle under a
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protective gas atmosphere. Because of the complicated
production process, the costs of a single armour plate
are consequently high.
In view of the price/output ratio, aluminium oxide has
hitherto been considered the ceramic material of
choice.
In the meantime, first attempts were made to use fibre-
reinforced composite materials with ceramic matrix
instead of the conventional ceramics for protection
r'"' against projectiles. For this purpose, trials were
carried out with SiC/SiC composite materials. They
displayed a limited damage to the material by the
impacting projectile, so that a protection by the
material is given against multiple bombardment from an
automatic weapon (multi hit). However, the protective
effect against projectiles is very low in comparison
with the known ceramics. (~rsini and Cottenot, 15th
International Symposium on Ballistics, Jerusalem,
1995) .
It is therefore the object of this invention to find a
ceramic material which has a low specific weight, which
has a good resistance to bombardment and thereby
withstands even a repeated bombardment.
Apart from this, the material which is sought is to be
able to be shaped as a large-surface element by means
of simple shaping processes.
Apart from this, it was a further object of the
invention to select the material in such a way that it
satisfies even high safety demands with respect to
bombardment and other impact-like loads. In this
connection, the material which is sought is to either
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form the protective element alone or have a
conventional rear-side reinforcement.
These objects are achieved in according with the
invention as a result of the use of elements made of a
fibre-reinforced composite material with a ceramic
matrix which contains at least 10% by weight silicon
carbide, the portion of carbon fibres and/or graphite
fibres with respect to the mass of the fibres being at
least 5% by weight, for partial or complete absorption
of at least one impact-like load focussed at a point,
the dimensions of which in a direction perpendicular to
the direction of the load are equal to or larger than
3 cm, preferably, however, equal to or larger than 10
cm and particularly preferably equal to or larger than
30 cm.
In order to meet the high safety demands with respect
to bombardment and other impact-like loads, elements
made of a carbon-fibre and/or graphite-fibre-reinforced
composite material with ceramic matrix are preferably
used. The elements consist of 40 to 85% by weight
silicon carbide, 5 to 55% by weight carbon and 0 to 30%
""' by weight silicon with respect to the total weight of
the composite material, the fibre portion of the
composite material being 5 to 40% by weight of the
total weight. In this connection, the average fibre
length of the reinforcing fibres is 0.2 to 15 mm and
the fibres are coated with at least one layer of
carbon. In this connection, the minimum thickness of
the elements in the direction of the action of force is
to meet the safety demands in an appropriate way, as
described in detail in the following. In order to save
on material and thus on costs, the thickness of the
elements is to be chosen to be as small as possible.
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The thickness of the elements made of the fibre-
reinforced composite material that are used can be
reduced in particular in composites according to the
invention in which the elements have a rear
reinforcement (also referred to as a backing), which is
generally stuck on.
In particular, the elements and composites in according
with the invention are used as structural components.
They are here used for armour plates, among other
things in the construction of vehicles of both civil
and military types including tanks, in automobile
construction, in the construction of aircraft, for
example of helicopters and aeroplanes, in shipbuilding
and in the construction of railway vehicles. The
armouring of stationary objects such as buildings and
strong rooms, for example, is also possible with the
elements and composites according to the invention, for
example as a structural component. Furthermore, the
elements and composites according to the invention can
also be used in protective vests.
Even projectiles making impact during travel through
-'~"' space can, with appropriate design of the elements and
composites according to the invention, be absorbed by
the latter so that a use for the protection of
spacecraft is also possible.
As a result of the use of the above-described elements
and composites, it is possible, in particular, for a
loading, for example by shell splinters, by
bombardment, for example by projectiles of any kind, to
be absorbed without the composite body cracking and
exploding into a plurality of pieces. This behaviour
is completely surprising and could not have been
expected, in particular because it was well known
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hitherto that non-fibre-reinforced ceramic materials
have a relatively brittle behaviour, and thus in the
case of bombardment, a plate made of this ceramic
material breaks up into a plurality of pieces. If the
elements and the elements which have been reinforced on
the rear side have a comparatively small thickness, a
shot can pass through, although without a shattering or
splintering, that is unwanted in conventional ceramic
materials, occurring at the same time.
Since the elements and composites according to the
invention do not shatter in the case of a point-focal
load, they also offer, in contrast to the known
ceramic-based armour platings, protection against
multiple bombardment. The elements according to the
invention made of reinforced composite materials with
ceramic matrix can therefore be used as armour plating
even with larger dimensions than the ceramics used
until now. In contrast to the latter, the one-part
elements and composites according to the invention can
have dimensions greater than 3 cm, preferably greater
than 10 cm and particularly preferably greater than 30
cm. Even larger dimensions are possible for the
.~~ elements so that, for example, portions of motor
vehicles can be replaced by them as armour-plating
protection.
Furthermore, the elements and composites according to
the invention also display a very good behaviour when
bombarded with automatic weapons (multi-hit
properties), because the material is weakened only
directly in the area of bombardment.
The fibre-reinforced composite material with ceramic
matrix of the elements according to the invention is
suitable for the substantial absorption of any impact-
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like load focussed at a point and can therefore be used
in the widest variety of ways in protection technology.
In particular, the use of the elements and composites
in the form of armour plates, for example for
automobiles, is of technical interest. Thus, for
example, it is possible to produce body portions or
body reinforcements for aeroplanes, missiles, trains or
even cars from this composite material and thus to
obtain vehicles which are completely secure against
bombardment without their weight increasing too much.
It is likewise possible, as a result of the use of the
fibre-reinforced composite material, to line the floor
region of a helicopter cockpit, for example.
A similar protection against bombardment can also be
given to ships, which can be manufactured at least
partially from this material.
It is likewise possible to use the fibre-reinforced
composite material for the protection of buildings,
bunkers and stores, for example fuel depots or
personnel shelters (tented camps), but also
~'~' telecommunications systems or radar stations, without
expensive or very heavy materials having to be used for
this purpose.
According to the invention, it is, of course, also
possible to use the fibre-reinforced composite material
as splinter protection, in particular as protection
against grenade splinters or grenade fragments. In
this case, the thickness of a protective plate made of
this composite material can even be made thinner than
in the case of the protection against projectiles.
The use of the fibre-reinforced composite material with
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ceramic matrix also includes protection in the civil
field, for example in the form of linings for
protective vests or generally for clothing worn on the
human body.
Furthermore, it is possible to obtain as a result of
the use described according to the invention a
protection of components of space stations, for example
against meteorite impacts.
The fibre-reinforced composite materials used according
'~ to the invention are distinguished in particular as a
result of the fact that the solid-body structure is
retained for a very long time during the energy action.
The incident energy is then transformed inside the
material.
Apart from this, the elements and composites used in
according with the invention are distinguished by a
particularly low specific weight. While known ceramic
materials such as aluminium oxide have a relatively
high specific weight (the specific weight of aluminium
oxide is 3.8 g/cm'), the composite materials used
'"w according to the invention have a clearly lower
specific weight of only 2.0 to 2.7 g/cm', in particular
2.3 to 2.4 g/cm'. This means that the composite
materials used according to the invention have in
particular a considerably lower specific weight than
the metallic, ballistic steels used hitherto, which
have a density of approximately 7.8 g/cm'. Their
specific weight, however, is even lower than that of
the known aluminium oxide ceramics. This makes
possible a pronounced weight saving potential when
these materials are used in vehicle construction,
aircraft construction and shipbuilding and also in the
protection of people.
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The composite bodies used according to the invention
are distinguished by a very good breaking behaviour, as
could be observed in the bombardment tests set out
later. The mechanical impulse energy of a projectile
that acts on the material is absorbed by way of
internal energy-distorting effects in the composite
body, inducing micro-cracks in the regions of the
matrix between the fibres, which gradually absorb the
energy of the bullets. In this connection, a
flattening or mushrooming of the impacting projectiles
results, in which case the bullet is braked and a
conversion of the kinetic energy into energy for crack
formation takes place.
In addition to carbon fibres and graphite fibres also
technically equivalent fibres, such as aluminium oxide
fibres, silicon nitride fibres and Si/H/C/N fibres,
which are presented in DE 197 il 829 C1, for example,
can be used as fibres. These can be contained in the
composite material of the elements and composites
according to the invention in addition to or instead of
the carbon fibres and graphite fibres. Preferably
fibres based on silicon, carbon, boron, nitrogen,
aluminium or mixtures thereof are used.
Basically, when selecting the fibres, the criterion
that these fibres are high-temperature fibres and can
thus withstand temperatures of up to approximately
1600°C should be fulfilled in order that they are not
quickly damaged upon infiltration with molten
materials. Conventional materials have no fibre
protection (shell) so that, for example, unprotected
carbon fibres are attacked upon infiltration with
silicon and it is impossible to obtain a ductile
material. The fibres used according to the invention
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therefore advantageously have a protective coating.
This preferably consists of at least one carbon layer
or graphite layer which results from the coking of
synthetic resins, for example, and/or other carbon-
donating substances and possibly subsequent
graphitising. A plurality of protective layers made of
carbon or graphite is particularly preferred. The
production of such a fibre provided with protective
shells) is known from DE 197 10 105 A1, for example.
In addition to short fibres, fibres having a greater
r.
length can also be used in the composite materials of
the elements according to the invention. Basically,
there is no restriction with respect to the fibre
length. If short fibres (fibre lengths of up to
approximately 4 mm) and fibres of greater length are
placed in the composite material, the longer fibres
above all contribute to the reinforcement of the
material. The portion of these longer fibres is
therefore denoted as reinforcing fibres in the
following and in the claims. In composite materials
which contain only short fibres, these are the
reinforcing fibres. The bundle thickness of the fibres
'~ (actual fibre bundle) is usually 1000 to 920,000
filaments. The fibres of the elements in according
with the invention preferably have a bundle thickness
of 1 to 3000 filaments.
An organic polymer such as polyacrylonitrile or
cellulose, for example, can even be used as starting
material for the fibres, from which material flat
shaped bodies such as woven fabrics or nonwoven fabrics
can be produced, as described in DE 195 17 911 A1. If
cellulose is used, it is made unmeltable in a pre-
process. It is also possible to use inorganic
polymers, which are spun to form nonwoven fabrics.
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Polysilanes, polysilazanes, carbosilanes, which are
made unmeltable, or nonwoven fabrics made of boron-
containing silazanes can be mentioned as materials. It
is favourable if woven fabrics are impregnated with
substances of low viscosity, such as furfurylcohol,
polyphenylenes, polyimides or polyacrylates, in order
to achieve a good wetting.
The composite materials used in the elements according
to the invention preferably also have phases of silicon
and carbon in the matrix in addition to silicon
carbide. It is particularly preferably, if the matrix
contains only phases of silicon carbide, silicon and
carbon.
The composite material of the elements and composites
in according with the invention contains at least 10%
by weight silicon carbide, advantageously 20% by weight
and particularly preferably 30% by weight with respect
to the total weight. The proportion of the fibres with
respect to the total weight should be at least 5% by
weight, preferably even 10%, and particularly
preferably is a proportion of the fibres above 15% by
weight. Furthermore, it is very advantageous if the
composite material of the elements and composites
according to the invention has a ductile breaking
behaviour.
In order to use the elements and composites according
to the invention also as protection against the
penetration of large calibre bullets, fibre-reinforced
composite materials having the following properties are
to be used.
A good protection is achieved if the composite material
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has, with respect to its total weight 40 to 85% by
weight, preferably 55 to 80% by weight and particularly
preferably 65 to 75% by weight silicon carbide, 5 to
55% by weight, preferably 10 to 40% by weight and
particularly preferably 15 to 25% by weight carbon
(including fibres) and 0 to 30% by weight, preferably 2
to 20% by weight and particularly preferably 5 to 15%
by weight silicon. Here, the proportion of the fibres
with respect to the total weight is to be 5 to 40% by
weight, preferably 8 to 30% by weight and particularly
preferably 10 to 20% by weight. Furthermore, the
average fibre length of the reinforcing fibres is here
between 0.2 mm and 15 mm, preferably between 0.5 mm and
mm and particularly preferably between 1 mm and 2 mm.
Apart from this, the fibres are coated with at least
one layer of carbon.
An element made of a composite material of this type
prevents the penetration of bullets having a kinetic
energy of up to 942.9 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 20 mm to 100 mm, preferably 24 mm to
60 mm and particularly preferably 28 mm to 40 mm. It
prevents the penetration of bullets having a kinetic
energy of up to 1510 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 25 mm to 100 mm, preferably 28 mm to
70 mm and particularly preferably 36 mm to 50 mm.
Apart from this, it prevents the penetration of bullets
having a kinetic energy up to 1805 J if the minimum
thickness of the element parallel to the direction of
impact of the bullet is 32 mm to 100 mm, preferably 36
mm to 80 mm and particularly preferably 40 mm to 60 mm.
Furthermore, an element made of a composite material of
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this type prevents the penetration of cone point-head
bullets having a soft core made of lead and a solid
jacket made of steel with a mass of up to 10.2 g and a
bullet velocity of up to 430 m/s if the minimum
thickness of the element parallel to the direction of
impact of the bullet is 20 mm to 100 mm, preferably 24
mm to 60 mm and particularly preferably 28 mm to 40 mm.
It prevents the penetration of flat-headed bullets
having a soft core made of lead and a solid jacket made
of copper with a mass of up to 15.6 g and a bullet
velocity of up to 440 m/s if the minimum thickness of
' the element parallel to the direction of impact of the
bullet is 25 mm to 100 mm, preferably 28 mm to 70 mm
and particularly preferably 36 mm to 50 mm. Apart from
this, it prevents the penetration of pointed bullets
having a soft core made of lead with steel penetrator
and~a solid jacket made of copper with a mass of up to
4.0 g and a bullet velocity of up to 950 m/s if the
minimum thickness of the element parallel to the
direction of impact of the bullet is 32 mm to 100 mm,
preferably 36 mm to 80 mm and particularly preferably
40 mm to 60 mm.
:~~' A composite made up of an element made of such a
composite material with a woven fabric of reinforcing
fibres, which preferably has a thickness of up to
15 mm, which element and which woven fabric are
connected to each other with an adhesive, prevents the
penetration of bullets having a kinetic energy of up to
942.9 J if the minimum thickness of the element
parallel to the direction of impact of the bullet is
3.2 mm to 30 mm, preferably 4.5 mm to 25 mm and
particularly preferably 6 mm to 20 mm. It prevents the
penetration of bullets having a kinetic energy of up to
1510 J if the minimum thickness of the element parallel
to the direction of impact of the bullet is 4 mm to
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40 mm, preferably 5.5 mm to 30 mm and particularly
preferably 7.5 mm to 25 mm. Apart from this, it
prevents the penetration of bullets having a kinetic
energy of up to 1805 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 4.8 mm to 50 mm, preferably 6 mm to 40 mm and
particularly preferably 8 mm to 30 mm. It prevents the
penetration of bullets having a kinetic energy of up to
2105 J if the minimum thickness of the element parallel
to the direction of impact of the bullet is 5.5 mm to
50 mm, preferably 7 mm to 40 mm and particularly
preferably 10 mm to 30 mm. It prevents the penetration
of bullets having a kinetic energy of up to 3272 J if
the minimum thickness of the element parallel to the
direction of impact of the bullet is 8 mm to 50 mm,
preferably 10 mm to 40 mm and particularly preferably
12 mm to 30 mm.
Furthermore, a composite made up of an element made of
such a composite material with a woven fabric of
reinforcing fibres, which preferably has a thickness of
up to 15 mm, which element and which woven fabric are
connected to each other with an adhesive, prevents the
'r~'' penetration of cone point-head bullets having a soft
core made of lead and a solid jacket made of steel with
a mass of up to 10.2 g and a bullet velocity of up to
430 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is
3.2 mm to 30 mm, preferably 4.5 mm to 25 mm and
particularly preferably 6 mm to 20 mm. It prevents the
penetration of flat-headed bullets having a soft core
made of lead and a solid jacket made of copper with a
mass of up to 15.6 g and a bullet velocity of up to
440 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is 4
mm to 40 mm, preferably 5.5 mm to 30 mm and
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particularly preferably 7.5 mm to 25 mm. Apart from
this, it prevents the penetration of pointed bullets
having a soft core made of lead with steel penetrator
and a solid jacket made of copper with a mass of up to
4.0 g and a bullet velocity of up to 950 m/s if the
minimum thickness of the element parallel to the
direction of impact of the bullet is 4.8 mm to 50 mm,
preferably 6 mm to 40 mm and particularly preferably
8 mm to 30 mm. It prevents the penetration of cone
point-head bullets having a soft core made of lead with
a steel penetrator and a solid jacket made of copper
with a mass of up to 7.9 g and a bullet velocity of up
to 730 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is
5.5 mm to 50 mm, preferably 7 mm to 40 mm and
particularly preferably 10 mm to 30 mm. It prevents
the penetration of pointed bullets having a soft core
made of lead and a solid jacket made of steel with a
mass of up to 9.5 g and a bullet velocity of up to
830 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is 8
mm to 50 mm, preferably 10 mm to 40 mm and particularly
preferably 12 mm to 30 mm.
A particularly good protection is achieved if the
composite material has, with respect to its total
weight 55 to 80% by weight and preferably 65 to 75% by
weight silicon carbide, 10 to 40% by weight and
preferably 15 to 25% by weight carbon (including
fibres) and 2 to 20% by weight and preferably 5 to 15%
by weight silicon. Here, the proportion of the fibres
with respect to the total weight is to be 8 to 30% by
weight and preferably 10 to 20% by weight.
Furthermore, the average fibre length of the
reinforcing fibres is here between 0.5 mm and 5 mm and
preferably between 1 mm and 2 mm. Apart from this, the
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fibres are coated with at least one layer of
graphitized carbon.
An element made of a composite material of this type
prevents the penetration of bullets having a kinetic
energy of up to 942.9 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 15 mm to 100 mm, preferably 19 mm to
60 mm and particularly preferably 23 mm to 40 mm. It
prevents the penetration of bullets having a kinetic
energy of up to 1510 J if the minimum thickness of the
'"' element parallel to the direction of impact of the
bullet is 20 mm to 100 mm, preferably 25 mm to
70 mm and particularly preferably 30 mm to 50 mm.
Apart from this, it prevents the penetration of bullets
having a kinetic energy up to 1805 J if the minimum
thickness of the element parallel to the direction of
impact of the bullet is 25 mm to 100 mm, preferably 31
mm to 80 mm and particularly preferably 37 mm to 60 mm.
Furthermore, an element made of a composite material of
this type prevents the penetration of cone point-head
bullets having a soft core made of lead and a solid
~,., jacket made of steel with a mass of up to 10.2 g and a
bullet velocity of up to 430 m/s if the minimum
thickness of the element parallel to the direction of
impact of the bullet is 15 mm to 100 mm, preferably 19
mm to 60 mm and particularly preferably 23 mm to 40 mm.
It prevents the penetration of flat-headed bullets
having a soft core made of lead and a solid jacket made
of copper with a mass of up to 15.6 g and a bullet
velocity of up to 440 m/s if the minimum thickness of
the element parallel to the direction of impact of the
bullet is 20 mm to 100 mm, preferably 25 mm to 70 mm
and particularly preferably 30 mm to 50 mm. Apart from
this, it prevents the penetration of pointed bullets
CA 02325123 2000-11-03
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having a soft core made of lead with steel penetrator
and a solid jacket made of copper with a mass of up to
4.0 g and a bullet velocity of up to 950 m/s if the
minimum thickness of the element parallel to the
direction of impact of the bullet is 25 mm to 100 mm,
preferably 31 mm to 80 mm and particularly preferably
37 mm to 60 mm.
A composite made up of an element made of such a
composite material with a woven fabric of reinforcing
fibres, which preferably has a thickness of up to
15 mm, which element and which woven fabric are
connected to each other with an adhesive, prevents the
penetration of bullets having a kinetic energy of up to
942.9 J if the minimum thickness of the element
parallel to the direction of impact of the bullet is
2.4 mm to 30 mm, preferably 3.5 mm to 25 mm and
particularly preferably 5 mm to 20 mm. It prevents the
penetration of bullets having a kinetic energy of up to
1510 J if the minimum thickness of the element parallel
to the direction of impact of the bullet is 3 mm to 40
mm, preferably 4.5 mm to 30 mm and particularly
preferably 6.5 mm to 25 mm. Apart from this, it
~,.. prevents the penetration of bullets having a kinetic
energy of up to 1805 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 3.6 mm to 50 mm, preferably 5 mm to 40 mm and
particularly preferably 7 mm to 30 mm. It prevents the
penetration of bullets having a kinetic energy of up to
2105 J if the minimum thickness of the element parallel
to the direction of impact of the bullet is 4 mm to 50
mm, preferably 6 mm to 40 mm and particularly
preferably 8 mm to 30 mm. It prevents the penetration
of bullets having a kinetic energy of up to 3272 J if
the minimum thickness of the element parallel to the
direction of impact of the bullet is 6 mm to 50 mm,
CA 02325123 2000-11-03
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preferably 7.5 mm to 40 mm and particularly preferably
9 mm to 30 mm.
Furthermore, a composite made up of an element made of
such a composite material with a woven fabric of
reinforcing fibres, which preferably has a thickness of
up to 15 mm, which element and which woven fabric are
connected to each other with an adhesive, prevents the
penetration of cone point-head bullets having a soft
core made of lead and a solid jacket made of steel with
a mass of up to 10.2 g and a bullet velocity of up to
~'' 430 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is
2.4 mm to 30 mm, preferably 3.5 mm to 25 mm and
particularly preferably 5 mm to 20 mm. It prevents the
penetration of flat-headed bullets having a soft core
made of lead and a solid jacket made of copper with a
mass of up to 15.6 g and a bullet velocity of up to
440 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is 3
mm to 40 mm, preferably 4.5 mm to 30 mm and
particularly preferably 6.5 mm to 25 mm. Apart from
this, it prevents the penetration of pointed bullets
,.. having a soft core made of lead with steel penetrator
f
and a solid jacket made of copper with a mass of up to
4.0 g and a bullet velocity of up to 950 m/s if the
minimum thickness of the element parallel to the
direction of impact of the bullet is 3.6 mm to 50 mm,
preferably 5 mm to 40 mm and particularly preferably
7 mm to 30 mm. It prevents the penetration of cone
point-head bullets having a soft core made of lead and
a steel penetrator and a solid jacket made of copper
with a mass of up to 7.9 g and a bullet velocity of up
to 730 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is
4 mm to 50 mm, preferably 6 mm to 40 mm and
CA 02325123 2000-11-03
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particularly preferably 8 mm to 30 mm. It prevents the
penetration of pointed bullets having a soft core made
of lead and a solid jacket made of steel with a mass of
up to 9.5 g and a bullet velocity of up to 830 m/s if
the minimum thickness of the element parallel to the
direction of impact of the bullet is 6 mm to 50 mm,
preferably 7.5 mm to 40 mm and particularly preferably
9 mm to 30 mm.
A extremely good protection is achieved if the
composite material has, with respect to its total
'~' weight 65 to 75% by weight silicon carbide, 15 to 25%
by weight carbon (including fibres) and 5 to 15% by
weight silicon. Here, the proportion of the fibres
with respect to the total weight is to be 10 to 20% by
weight. Furthermore, the average fibre length of the
reinforcing fibres is here between 1 mm and 2 mm.
Apart from this, the fibres are coated with at least
three layers of graphitized carbon.
An element made of a composite material of this type
prevents the penetration of bullets having a kinetic
energy of up to 942.9 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 12 mm to 100 mm, preferably 15 mm to
60 mm and particularly preferably 18 mm to 40 mm. It
prevents the penetration of bullets having a kinetic
energy of up to 1510 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 16 mm to 100 mm, preferably 20 mm to
70 mm and particularly preferably 24 mm to 50 mm.
Apart from this, it prevents the penetration of bullets
having a kinetic energy up to 1805 J if the minimum
thickness of the element parallel to the direction of
impact of the bullet is 20 mm to 100 mm, preferably 24
mm to 80 mm and particularly preferably 28 mm to 60 mm.
CA 02325123 2000-11-03
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Furthermore, an element made of a composite material of
this type prevents the penetration of cone point-head
bullets having a soft core made of lead and a solid
jacket made of steel with a mass of up to 10.2 g and a
bullet velocity of up to 430 m/s if the minimum
thickness of the element parallel to the direction of
impact of the bullet is 12 mm to 100 mm, preferably 15
mm to 60 mm and particularly preferably 18 mm to 40 mm.
It prevents the penetration of flat-headed bullets
having a soft core made of lead and a solid jacket made
of copper with a mass of up to 15.6 g and a bullet
velocity of up to 440 m/s if the minimum thickness of
the element parallel to the direction of impact of the
bullet is 16 mm to 100 mm, preferably 20 mm to 70 mm
and particularly preferably 24 mm to 50 mm. Apart from
this, it prevents the penetration of pointed bullets
having a soft core made of lead with steel penetrator
and a solid jacket made of copper with a mass of up to
4.0 g and a bullet velocity of up to 950 m/s if the
minimum thickness of the element parallel to the
direction of impact of the bullet is 20 mm to 100 mm,
preferably 24 mm to 80 mm and particularly preferably
.r'"' 28 mm to 60 mm.
A composite made up of an element made of such a
composite material with a woven fabric of reinforcing
fibres, which preferably has a thickness of up to
15 mm, which element and which woven fabric are
connected to each other with an adhesive, prevents the
penetration of bullets having a kinetic energy of up to
942.9 J if the minimum thickness of the element
parallel to the direction of impact of the bullet is 2
mm to 30 mm, preferably 2.5 mm to 25 mm and
particularly preferably 4 mm to 20 mm. It prevents the
penetration of bullets having a kinetic energy of up to
CA 02325123 2000-11-03
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1510 J if the minimum thickness of the element parallel
to the direction of impact of the bullet is 2.5 mm to
40 mm, preferably 3 mm to 30 mm and particularly
preferably 5.5 mm to 25 mm. Apart from this, it
prevents the penetration of bullets having a kinetic
energy of up to 1805 J if the minimum thickness of the
element parallel to the direction of impact of the
bullet is 3 mm to 50 mm, preferably 4 mm to 40 mm and
particularly preferably 6 mm to 30 mm. It prevents the
penetration of bullets having a kinetic energy of up to
2105 J if the minimum thickness of the element parallel
to the direction of impact of the bullet is 3.5 mm to
50 mm, preferably 4.5 mm to 40 mm and particularly
preferably 7 mm to 30 mm. It prevents the penetration
of bullets having a kinetic energy of up to 3272 J if
the minimum thickness of the element parallel to the
direction of impact of the bullet is 5 mm to 50 mm,
preferably 6 mm to 40 mm and particularly preferably 8
mm to 30 mm.
Furthermore, a composite made up of an element made of
such a composite material with a woven fabric of
reinforcing fibres, which preferably has a thickness of
,r' up to 15 mm, which element and which woven fabric are
connected to each other with an adhesive, prevents the
penetration of cone point-head bullets having a soft
core made of lead and a solid jacket made of steel with
a mass of up to 10.2 g and a bullet velocity of up to
430 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is 2
mm to 30 mm, preferably 2.5 mm to 25 mm and
particularly preferably 4 mm to 20 mm. It prevents the
penetration of flat-headed bullets having a soft core
made of lead and a solid jacket made of copper with a
mass of up to 15.6 g and a bullet velocity of up to
440 m/s if the minimum thickness of the element
CA 02325123 2000-11-03
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parallel to the direction of impact of the bullet is
2.5 mm to 40 mm, preferably 3 mm to 30 mm and
particularly preferably 5.5 mm to 25 mm. Apart from
this, it prevents the penetration of pointed bullets
having a soft core made of lead with steel penetrator
and a solid jacket made of copper with a mass of up to
4.0 g and a bullet velocity of up to 950 m/s if the
minimum thickness of the element parallel to the
direction of impact of the bullet is 3 mm to 50 mm,
preferably 4 mm to 40 mm and particularly preferably
6 mm to 30 mm. It prevents the penetration of cone
point-head bullets having a soft core made of lead and
a steel penetrator and a solid jacket made of copper
with a mass of up to 7.9 g and a bullet velocity of up
to 730 m/s if the minimum thickness of the element
parallel to the direction of impact of the bullet is
3.5 mm to 50 mm, preferably 4.5 mm to 40 mm and
particularly preferably 7 mm to 30 mm. It prevents the
penetration of pointed bullets having a soft core made
of lead and a solid jacket made of steel with a mass of
up to 9.5 g and a bullet velocity of up to 830 m/s if
the minimum thickness of the element parallel to the
direction of impact of the bullet is 5 mm to 50 mm,
..~~ preferably 6 mm to 40 mm and particularly preferably 8
mm to 30 mm.
In addition to the fibres, various fillers can also be
placed in the matrix. In particular, silicides,
carbides, borides, metals and carbon, for example in
the form of soot, graphite, coke or mixtures of these,
are suitable as fillers. Silicon carbides, B4C, soot,
graphite or zirconium borides are of particular
interest here. The use of soot and/or graphite is
particularly preferred because a good conversion into
SiC is rendered possible by these substances. The use
of B4C is common in applications at the present time if
CA 02325123 2000-11-03
-25-
er.
a high level of hardness of the composite body is to be
achieved. Zirconium borides are used because of their
resistance to high temperatures. Therefore, advantages
are to be expected when they are used for the composite
bodies used according to the invention, in particular
in the case of bombardment with signal ammunition. If,
however, composite bodies having a particularly low
specific weight are to be used, it is preferable to use
fillers other than zirconium boride, which has a high
density.
The amount of the fillers to be used if appropriate can
be determined as a function of the properties of the
composite body that are to be achieved. When reacting
fillers such as soot or graphite are used, the amount
is preferably up to 40~ by weight, with respect to the
original mixture. At higher amounts, a deformation of
the body or even cracking can occur. More preferably,
the amount is up to 30~s by weight. If non-reacting
fillers, for example SiC, are used, even higher
concentrations are usable. The proportion of such
fillers depends fundamentally on the brittleness and
the hardness which are to be adjusted.
A significant advantage of the use of the fibre-
reinforced composite material with ceramic matrix lies
in that the elements can be produced directly in the
shape of the desired structural component, so that
shaping steps after the production of the elements can
be avoided and thus a further reduction in costs in the
production of protective plates or armour plates, for
example, is obtained. In view of the high breaking
strength of the elements, it is not absolutely
necessary to provide the elements according to the
invention with a rear-side reinforcement, in which case
the reinforcing material, such as fibre fabric (for
CA 02325123 2000-11-03
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example aramide fibres) or metal plates, is glued on to
the rear side of the composite material in order to
obtain a bombardment-resistant armour plate. Instead,
the composite body can itself already form this armour
plate. However, the thickness of an element according
to the invention made of a composite material is
greater than that required for the element if, as a
result of the rear-side reinforcement, a composite
according to the invention having the same effect is
made available.
The production of the composite material which is
fibre-reinforced at least partly with carbon fibres
and/or graphite fibres and has a ceramic matrix which
contains silicon carbide can, for example, take place
according to the processes known from DE 197 11 829 C1
or DE 197 10 105 AI. Reference to these two printed
publications is made explicitly with respect to the
production process.
Basically, all known processes can be used in order to
produce fibre-reinforced C/SiC ceramics. In the
processes cited above, the following production steps
'"° are carried out in order to produce composite materials
into which individual fibres (or fibre bundles) are
incorporated.
The incorporated fibres are, as described in DE 197 11
829 C1 and DE 197 10 105 A1, for example, pre-treated
or produced and, by way of a mixer, mixed with a
carbon-donating resin and moulded into the initial
shape by way of a pressing mould and hardened at
temperatures of up to approximately 150°C. The moulded
bodies (CFC preliminary bodies) which result in this
way are pyrolysed at temperatures of up to
approximately 1000°C and possibly subsequently
CA 02325123 2000-11-03
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graphitised at temperatures of up to approximately
2000°C.
The CFC preliminary body obtained in this way is
subsequently impregnated with liquid silicon at
temperatures of up to approximately 1800°C in a vacuum.
In this connection, a large portion of the matrix
carbon reacts in an exothermal reaction with the
silicon which is incorporated to form silicon carbide.
Due to a special pre-treatment of the fibres, the
carbon fibres are retained during this reaction and can
'~ thus contribute to the ductilisation of the ceramics.
Also suitable are the known 2D and 3D CFC woven-fabric
structures with large volumetric contents of the fibers
which can be produced, inter alia, directly from
polyacrylonitrile planar fibre structures by way of the
direct oxidation process and by subsequent pyrolysis.
Tn this connection, the following process steps in
particular are carried out.
The carbon-fibre reinforcing structure is made into a
shape which corresponds to the desired final shape.
The fibre body is impregnated with a resin matrix in a
vacuum and under pressure at 130°C " and after hardening
and removal from the mould, is subsequently processed
according to need.
The CFK preliminary bodies which result in this way are
then pyrolysed at temperatures of up to 1000°C. Then, a
secondary compression of this CFC material with a
pitch-based or resin-based carbon-containing polymer
can take place in one or more steps, with a further
pyrolysis step following each secondary-compression
step. In this way, a CFC material which is suitable
for the subsequent infiltration is obtained. In that
CA 02325123 2000-11-03
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material the carbon fibres are sufficiently protected
against the attack of the liquid silicon in particular.
Subsequently, a graphitisation of the CFC composite
material at temperatures of up to approximately 2000°C
can take place.
The siliconizing is carried out at temperatures of up
to approximately 1800°C in a vacuum.
For example, the shapes of vehicle doors or certain
aircraft components can be formed directly by way of
the concrete processes described above.
In addition to silicon, other materials also come into
consideration as infiltration material, which materials
are added to the silicon. Basically, the materials
used for infiltration must be able to melt in the
temperature range up to 1800°C. Aluminium, boron,
magnesium, nitrogen, carbon and compounds or mixtures
thereof as well as silicides come into consideration as
further infiltration materials. Even silicides
exclusively can be infiltrated in order to form a
matrix containing silicon carbide.
,r1
Particularly preferably, silicon is used as
infiltration material during the production of the
composite bodies. During the addition of other
substances, silicides, such as, for example, molybdenum
silicides, iron silicides, chromium silicides, tantalum
silicides or mixtures, are preferably added to silicon.
Materials of this type can alter the melting point of
the infiltration material.
It is likewise also possible to use silicon-based
polymers as infiltration material. Examples of such
polymers are, for example, baron-containing
CA 02325123 2000-11-03
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polysilazanes.
In the following, exemplary embodiments are presented
in order to explain this invention further.
Examples 1 and 2: Production of elements made of a
fibre-reinforced composite material with ceramic
matrix.
First of all, a prepreg is produced from 3K carbon
fibre bundles (3000 individual filaments), the carbon
fibres having being produced on the basis of PAN
fibres. For this purpose, the fibre bundles were
interlaced to a twill fabric, the woven fabric was
subsequently saturated in phenolic resin Cresol type)
and provided with an release paper on both sides.
After this, the resinated fabric was heated to 130°C in
order to establish the tackiness of the prepreg.
Subsequently, the prepreg plates were laid on top of
each other and pressed to form a compact body. This
was then baked at 900°C, the burning curve having a rise
of 5°C per minute in the range between 400°C and 600°C.
Then, three times, one after another, the CFC body
obtained in this way was first impregnated with a coal
tar pitch with a softening point of 60°C and then baked,
again at 900°C, in order to compact it further.
The CFC body obtained in this way was then first broken
up into small pieces in a jaw breaker (manufacturer:
Alpine Hosokawa) and subsequently cut into fibre
bundles in a cutting mill (manufacturer: Alpine
Hosokawa). The fibre bundles were then classified in a
wobble screening plant (manufacturer: Allgaier) into
individual fibre fractions, the sieve inserts (sieving
area 1.15 m2) having a clear mesh aperture of 0.5 mm,
CA 02325123 2000-11-03
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1 mm; 2 mm, 3 mm, 4 mm and 6 mm in according with ISO
9044. As a result of this sieving process, different
fibre fractions were obtained, as a result of which
there were, among others, a fraction A with fibres of
the length 12.45 mm to 17.55 mm and the width 660 ~tm to
2.26 mm, a fraction B with fibres of the length 8.5 mm
to 13.5 mm and the width 690 ftm to 2.21 mm, a fraction
C with fibres of the length 5.5 mm to 10.5 mm and the
width 760 ~m to 2.16 mm, a fraction D with fibres of
the length 0.2 mm to 3 mm and the width 200 ~m to 1 mm,
a fraction E with fibres of the length 0.1 mm to 3 mm
and the width 50 to 500 Eun and a fraction F with fibres
of the length 0.3 mm and the width 8 to 200 Vim.
Subsequently this, for samples of Example 1, a mixture
1 made up of 70$ of the total weight fibres, in
according with the composition: 35~ fraction D, 35~
fraction E and 30~ fraction F, and 30$ of the total
weight of phenolic resin Cresol type) as binding agent,
and for samples of Example 2, a mixture 2 made up of
70~ of the total weight fibres, in according with the
composition: 12~ fraction A, 18~ fraction B, 40~
fraction C and 30~ fraction D, and 21~ of the total
~'~ weight phenolic resin Cresol type) and 9$ of the total
weight coal tar pitch (softening point: 230°C) as
binding agent were produced in a Z-arm kneader
(manufacturer: Werner & Pfleiderer) by mixing for 15
minutes at a rotational speed of 30 1/min.
Subsequently, in each case 1200 g of the mixture 1 was
pressed in a stamping press in a square pressing mould
of the side length 325 mm at a specific pressure of 12
Kp/cm2 and a temperature of 130°C. This temperature was
maintained for 3 hours at constant mould pressure.
After cooling to 30°C, the cured plate was removed from
the pressing mould. As a result of this manner of
proceeding, a CFK plate with a height (thickness) of 10
CA 02325123 2000-11-03
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mm and a density of 1.2 g/cm3 was obtained.
In an analogous manner, plates with a thickness of
38 mm and a density of 1.18 g/cm3 were obtained in each
case from 5100 g of the mixture 2.
After this, the carbonisation of the samples took place
at 900°C under protective gas (heating rate of 2 K/min).
The cooling of the plates to room temperature took
place in an uncontrolled manner at up to 10 K/min.
After carbonisation, these plates had densities of 1.05
.,
g/cm3 (Example 1) and 1.03 g/cm3 (Example 2).
Subsequently, the infiltration of the samples at 1700°C
with liquid silicon took place in a vacuum in a high-
temperature furnace with a silicon supply (particle
size up to 5 mm) of one and a half times the sample
weight, as a result of which the SiC structure of the
matrix of the samples is generated. In this
connection, the siliconization took place first of all
with a temperature rise of 10 K/min to 1400°C and then 5
K/min to 1800°C. The temperature was then held for 45
minutes, then a temperature drop with 5 K/min to 1400°C
~-~ and subsequently an uncontrolled cooling took place.
The C/SiC composite materials obtained in this way had
densities of 2.4 g/cm3 and 2.35 g/cm3. The plates made
of the C/SiC composite material of Example 1 that were
produced in this way had a fibre proportion with
respect to the total weight of 15~ and a composition
with respect to the total weight of 68~ silicon
carbide, 22~ carbon and 10$ silicon. The average fibre
length was 1.5 mm. The plates made of the C/SiC
composite material of Example 2 had a fibre proportion
with respect to the total weight of 17~ and a
composition with respect to the total weight of 58~
silicon carbide, 31~ carbon and 11~ silicon. The
CA 02325123 2000-11-03
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average fibre length of the reinforcing fibres was
mm.
Example 3: Production of an element made of a fibre-
reinforced composite material with ceramic matrix with
a rear-side reinforcement.
The 10 mm thick plates produced in according with
Example 1 were, additionally provided with a
conventional rear-side reinforcement system (backing)
in order to use them for protection against
bombardment. In order to do this, the rear side of the
ceramic plate was first blasted with silica sand and
after this 10 layers of aramide fibre fabric T 750
(Akzo Nobel, Germany) were glued to the rear side of
the C/SiC plate with the PUR glue SIKAFLEX7 225 FC
(manufacturer: Sika Chemie GmbH, Germany) and an
adhesive primer.
Results of bombardment tests
Bombardment tests were carried out with the elements
made of fibre-reinforced composite materials with
'"" ceramic matrix with rear-side reinforcement in
according with Example 3 and without rear-side
reinforcement in according with Example 2. The testing
process took place in a penetration test according to
the Euro standard, DIN EN 1523. The test requirements
were the impeding of penetration in the resistance
classes according to Table 1 of the Euro standard DIN
EN 1522. In order to set up the test, the plates were
clamped on a stand, the test sample being fastened at
an angle of 90° to the shooting direction. The firing
distance was 5 or 10 m. The dispersion distance was
120 mm ~ 10 mm.
First, bombardment tests were carried out on plates
CA 02325123 2000-11-03
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having the dimensions 325 mm x 278 mm x 38 mm which
were produced from plates in according with Example 2.
It was found that the plates resisted the following
bombardment tests, with at least three shots being
fired at a plate in each case.
Test 1 (bombardment class FB 3)
A weapon type "test barrel" with a 357 magnum calibre
was used as the weapon, and the bullet had a solid
jacket made of steel, a cone point-head and a soft core
r~.
made of lead. The bullet weight was 10.2 g. The test
distance was 5 m. The bullet velocity was 430 m/s, the
bullet energy 942.9 J.
Test 2 (bombardment class FB 4)
A weapon type "test barrel" with a 44 Rem. magnum
calibre was used as the weapon, and the bullet had a
solid jacket made of copper, a flat-head and a soft
core made of lead. The bullet weight was 15.6 g. The
test distance was 5 m. The bullet velocity was 440
m/s, the bullet energy 1510 J.
It emerged that the plates in the case of this test are
also resistant to a multiple bombardment if the bullets
hit with a spacing of 50 mm, which corresponds to the
effect of automatic weapons (multi-hit capability).
Test 3 (bombardment class FB 5)
A weapon type "test barrel" with a 5.56 mm x 45 mm
calibre was used as the weapon, and the bullet had a
solid jacket made of copper, a pointed head and a soft
core made of lead with steel penetrator (type SS 109).
The bullet weight was 4.0 g. The test distance was 10
CA 02325123 2000-11-03
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m. The bullet velocity was 950 m/s, the bullet energy
1805 J.
In all of these bombardment tests on the large-sized
protective elements made of the C/SiC composite
material, no crack preventing a further use as
protection appeared in the elements.
Apart from this, elements having the dimensions 300 mm
x 300 mm in according with Example 3, which had a C/SiC
composite-material plate of only 10 mm thickness and a
rear-side reinforcement, were exposed to the
bombardment tests.
Test 4 (bombardment class FB 3)
A weapon type "test barrel" with a 357 magnum calibre
was used as the weapon, and the bullet had a solid
jacket made of steel, a cone point-head and a soft core
made of lead. The bullet weight was 10.2 g. The test
distance was 5 m. The bullet velocity was 430 m/s, the
bullet energy 942.9 J.
-''"'~ Test 5 (bombardment class FB 4)
A weapon type "test barrel" with a 44 Rem. magnum
calibre was used as the weapon, and the bullet had a
solid jacket made of copper, a flat-head and a soft
core made of lead. The bullet weight was 15.6 g. The
test distance was 5 m. The bullet velocity was 440
m/s, the bullet energy 1510 J.
It emerged that the plates in the case of this test are
also resistant to a multiple bombardment if the bullets
hit with a spacing of 50 mm, which corresponds to the
effect of automatic weapons (multi-hit capability).
CA 02325123 2000-11-03
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Test 6 (bombardment class FB 4+)
A Kalashnikov AK 47 with a 7.62 mm x 39 mm calibre was
used as the weapon, and the bullet had a solid jacket
made of copper, a cone point-head and a soft core made
of lead with steel penetrator. The bullet weight was
7.9 g. The test distance was 10 m. The bullet
velocity was 730 m/s, the bullet energy 2105 J.
Test 7 (bombardment class FB 5)
A weapon type "test barrel" with a 5.56 mm x 45 mm
calibre was used as the weapon, and the bullet had a
solid jacket made of copper, a pointed head and a soft
core made of lead with steel penetrator (type SS 109).
The bullet weight was 4.0 g. The test distance was
m. The bullet velocity was 950 m/s, the bullet
energy 1805 J.
Test 8 (bombardment class FB 6)
A weapon type "test barrel" with a 7.62 mm x 51 mm
°'"" calibre was used as the weapon, and the bullet had a
solid jacket made of steel, a pointed head and a soft
core made of lead. The bullet weight was 9.5 g. The
test distance was 10 m. The bullet velocity was 830
m/s, the bullet energy 3272 J.
No crack preventing a further use as protection
appeared in the elements even in these bombardment
tests on the large-sized protective elements made of
the C/SiC composite material with rear-side
reinforcement.
The prevailing temperature in the bombardment tests was
CA 02325123 2000-11-03
~.
-36-
20 to 22°C.
On the basis of the above results, it is evident that
elements made of C/SiC composite materials with and
without rear reinforcement can be bombarded without
shattering. In this connection, the plates display a
resistance even in the case of high demands. In
particular, the thickness of the C/SiC plates in the
case of a rear-side reinforcement according to
conventional technology can be chosen to be so small
that an economical use is also provided and despite
this a high level of safety is ensured.
f..
