FIELD OF INVENTION
[0001] The present invention relates to a method for the improvement of vibration resilience
in a rotating press element of a fiber web machine, to a coating, to a press element,
and to a method for the reconditioning of the coating or press element. In particular,
but not limited to, the invention relates to a composite coating formed of layers
for the roll of a fiber web machine and to a method for forming the composite coating
of layers.
BACKGROUND OF INVENTION
[0002] Elastic and polymeric roll coatings are used in web-carrying machines, such as paper
machines, for example on guide rolls or as press roll surfaces with a nip, used for
removing water from webs, or in sizing and film transfer as well as in calendering
to give the web the finished properties. Properties required from the composite roll
coatings in paper machines typically include wear resistance and sufficient strength
properties. In addition to these properties, one factor which limits performance especially
in newer multinip calenders is the ability of the coating to resist the so-called
barring phenomenon. The barring phenomenon can cause serious problems in terms of
the runnability, production quality and maintenance of the paper machine, which is
why the goal is to prevent its occurrence by every means possible. The barring phenomenon
is generated by self-sustained vibration taking place in the calender. This vibration
is influenced by many factors such as mechanical resonance, back feed from a previous
load, and the properties of the composite coating used.
[0003] The goal is to prevent the barring phenomenon typically by suppressing the resonance
by means of better design and materials, by using mass attenuators, or by adjusting
the running parameters of the calender. In applications with a nip, a constant increase
in speeds, loads and temperatures leads to an elevated likelihood of the barring phenomenon
with elastic coatings. The barring phenomenon, in turn, gradually leads to such a
vibration level that the coating needs to be replaced prematurely. Attempts have been
made to improve the properties of the composite coating for better resilience against
the barring phenomenon through means such as a high filler content, which reduces
the deformation of the coating and improves its wear resistance.
[0004] The impulse for the barring phenomenon usually comes from a source other than the
coating, but the proper coating properties can pre-empt barring. One variable present
in the emergence of the barring phenomenon are the viscoelastic properties of the
coating. It has been proven empirically that improved wear resistance also extends
the running period. The impact of the adjustment of the viscoelastic properties is
known relatively well when operating with a short measuring time within the natural
frequency range environment of the nip, but there is less knowledge of the viscoelastic
behaviour and of the changes in this behaviour in long-term operation.
[0005] The wear of the coating and the build-up of vibration can be significantly reduced
by making a harder coating, which has a high modulus of elasticity. As is well known,
this can be achieved by using a more rigid matrix raw material (there are a variety
of rubber, PU, epoxy and thermoplast options with different moduli of elasticity),
a higher filler content, or more rigid reinforcement fibers and on the other hand
a higher reinforcement fiber content. However, there is an optimal coating hardness
range for a particular application in view of the process, which is why it is not
possible to infinitely increase the modulus of elasticity of the coating. As an example,
in sizing it is advantageous to use soft coatings on the rolls, where the modulus
of elasticity of the coatings cannot be too high. On the other hand, in calendering
it is advantageous to use a sufficiently elastic roll coating so that the calender
nip would not be too short, and, on the other hand, so that calendering would compact
the paper in a sufficiently even manner. As is well known, deformations take place
in the coating during calendering, primarily in the surface layer with a lower rigidity.
[0006] The elastic coatings used in the nips usually consist of two or more layers so that
the hardness of a lower layer is typically greater than the hardness of the surface
layer. Publication
US 5887517 presents one example of such a layered coating constructed on a roll body, where
the layers are softer than the adjacent layer when the distance from the metallic
roll body increases; in other words, the hardness of the coating decreases gradually
in the radial direction.
[0007] Publication
US 5023985A presents a polymer-coated roll, where the outer surface is arranged of a coating
which is several times thinner than the thickness of the soft polymer coating.
[0008] The prior art solutions cannot prevent the occurrence of the barring phenomenon sufficiently
well in all cases, which means that barring becomes a major factor limiting the runnability
of applications with a nip.
SUMMARY
[0009] According to a first aspect of the invention, the present invention provides a method
for the improvement of vibration resilience in the rotating press element of a fibre
web machine, in particular in a roll, where the press element has an elastic coating
which comprises a base layer made of a polymer material on the body of the press element
and a surface layer made of a polymer material as a wearing layer on top of the base
layer, and where the surface layer comprises an outer surface as the outermost radial
point and where the radial modulus of elasticity of the surface layer beneath the
outer surface of the coating is adjusted to a level lower than the radial modulus
of elasticity of the outer surface.
[0010] The radial modulus of elasticity of the base layer is preferably adjusted to a level
lower than the radial modulus of elasticity of the outer surface.
[0011] An intermediate layer, which is softer in the radial direction than the surface layer,
is preferably arranged between the surface layer and the base layer.
[0012] The radially outermost part of the surface layer, in other words its upper part which
extends to a depth of 0.2 to 1 mm from the surface, is preferably arranged to be harder
in the radial direction than the inner part of the surface layer, in other words its
lower part, which is radially beneath the upper part. The upper part of the surface
layer, where the upper part extends to a depth of 0.2 to 1 mm from the surface, is
preferably arranged to be 15 to 20% harder in the radial direction than the lower
part of the surface layer.
[0013] The upper part of the surface layer is preferably hardened by means of heat treatment
directed at the upper part using a temperature which is preferably higher than the
temperature used in the original heat treatment of the surface layer.
[0014] A component or additive which reacts to UV radiation is preferably added to the polymer
material of the surface layer, and the upper part is allowed to harden by natural
UV radiation or the upper part is hardened by means of UV treatment.
[0015] The outer surface of the surface layer is preferably hardened by means of sol-gel
hardening.
[0016] The temperature in the lower part of the surface layer is preferably arranged to
be higher than the temperature in the outer surface or in the upper part of the surface
layer so that the temperature difference corresponds to the targeted difference in
the modulus of elasticity required to make the lower part softer than the upper part.
[0017] The base layer is preferably arranged as a layered structure, where rigid layers
reinforced with continuous fibers alternate with less rigid layers reinforced with
discontinuous fibers.
[0018] The layer beneath the surface layer is preferably provided with a matrix polymer,
which has a lower modulus of elasticity and a higher loss factor than the surface
layer.
[0019] The thermal conductivity of the layer beneath the surface layer is preferably adjusted
to be higher than the thermal conductivity of the surface layer.
[0020] An intermediate layer is preferably arranged between the surface layer and the base
layer, where the intermediate layer has a higher thermal conductivity than the surface
layer.
[0021] Carbon fiber or heat-conducting fillers are preferably used in the layer beneath
the surface layer to achieve a better thermal conductivity.
[0022] The thermal conductivity of the base layer is preferably arranged to be higher than
the thermal conductivity of the surface layer.
[0023] According to a second aspect of the invention, the present invention provides an
elastic coating for the rotating press element of a fibre web, in particular for a
roll, where the coating comprises a base layer made of a polymer material fastened
on the body of the press element of a fibre web, and a surface layer made of a polymer
material, where the surface layer is formed as a wear layer on top of the base layer
and where the surface layer comprises an outer surface as the outermost radial point
and where the radial modulus of elasticity of the surface layer beneath the outer
surface of the coating is lower than the radial modulus of elasticity of the outer
surface.
[0024] The polymer material in the surface layer is preferably polyurethane. The polymer
material in the surface layer is preferably epoxy.
[0025] The radial modulus of elasticity of the base layer is preferably lower than the radial
modulus of elasticity of the outer surface.
[0026] An intermediate layer, which is softer in the radial direction than the surface layer,
is preferably arranged between the surface layer and the base layer.
[0027] The upper part of the surface layer, where the upper part extends to a depth of 0.2
to 1 mm from the surface, is preferably arranged to be harder in the radial direction
than the lower part of the surface layer, where the lower part is radially beneath
the upper part. The upper part, which extends to a depth of 0.2 to 1 mm from the surface,
is preferably arranged to be 15 to 20% harder in the radial direction than the lower
part of the surface layer.
[0028] The upper part of the surface layer is preferably hardened by means of heat treatment
directed at the upper part.
[0029] A component or additive, such as a photoinitiator, which reacts to UV radiation is
preferably added to the polymer material of the surface layer, and the surface layer
is hardened by UV radiation.
[0030] The surface of the surface layer is preferably hardened by means of sol-gel hardening.
[0031] The outer surface of the surface layer is preferably treated with a material in sol-gel
format, applied on the surface layer. The material can be of sol-gel which contains
Si compounds. The material can be allowed to be absorbed, and the surface can be dried
for example at an elevated temperature.
[0032] The base layer is preferably arranged as a layered structure, where rigid layers
reinforced with continuous fibers alternate with less rigid layers reinforced with
discontinuous fibers.
[0033] The layer beneath the surface layer is preferably provided with a matrix polymer,
which has a lower modulus of elasticity and a higher loss factor than the surface
layer.
[0034] The thermal conductivity of the layer beneath the surface layer is preferably higher
than the thermal conductivity of the surface layer.
[0035] Carbon fiber or heat-conducting fillers can preferably be used in the layer beneath
the surface layer to achieve a better thermal conductivity.
[0036] The polymer material used at least in the surface layer of the elastic coating is
preferably of polyurethane, polyurea or epoxy.
[0037] According to a third aspect of the invention, the present invention provides a fiber
web press element, in particular a roll, where the press element comprises a coating
according to some aspect or embodiment of the invention.
[0038] According to a fourth aspect of the invention, the present invention provides a method
for the reconditioning of the coating or fiber web press element according to some
aspect or embodiment, in which method some of the outer surface of the surface layer
is removed in the radial direction of the coating to below the deepest point of wear,
and the exposed outer surface of the surface layer is hardened.
[0039] The wear of the coating and on the other hand the build-up of vibration can be significantly
slowed down without having to essentially change the optimal hardness of the roll.
The build-up of the barring phenomenon can be slowed down in demanding applications
with a nip, such as in multinip calenders and in film transfer.
[0040] Solutions according to the aspects and embodiments described in this application
can be used to achieve a composite coating structure which dampens vibrations and
is hence better resilient to the barring phenomenon.
[0041] The removal of vibrations, which are relevant in terms of the barring phenomenon,
from fiber web machine applications with a nip, such as from a calender, and hence
the control of barring provide significant advantage in the improvement of current
production processes and in the further development of fiber web manufacturing technologies.
[0042] According to some embodiments of the invention, it is possible to achieve a coating
with an improved service life as compared to prior art coatings for the rolls of a
fiber web machine. According to some embodiments, the wear resistance of the coating
can be improved and hence a coating solution with a long maintenance interval can
be achieved.
[0043] The wear of the coating and on the other hand the build-up of vibration can be significantly
slowed down without having to essentially change the optimal hardness of the roll.
[0044] The embodiments of the present invention are described or have been described only
in conjunction with some aspect or aspects of the invention. A professional in the
field understands that any embodiment of any aspect of the invention can be applied
in the same aspect and other aspects of the invention on its own or in combination
with the other embodiments.
BRIEF DESCRIPTION OF FIGURES
[0045] The invention is described below in way of example by making reference to the enclosed
figures, where:
FIGS. 1 - 3 present some preferred coatings formed around the body of the roll; and
FIGS. 4 - 6 present theoretical diagrammatic examples of the changes in the deformation
of the surface layer and of the changes in the deformation energy as a function of
the change in the modulus of elasticity of the surface layer.
DETAILED SPECIFICATION
[0046] In the below specification, similar reference numbers refer to similar parts. It
is to be noted that the figures presented are not completely on scale and that they
primarily only serve the purpose of illustrating some embodiments of the invention.
[0047] FIGS. 1 - 3 present some coatings 10 formed around the body 130 of the roll 9. The
body 130 is preferably hollow, but the body can also be solid. The composite coating
10 can be used to improve the vibration damping capability of the coating and hence
to reduce the occurrence of the barring phenomenon.
[0048] In FIG. 1, the coating 10 comprises a surface layer 110, whose outer surface is denoted
with reference number 100, and a base layer 120, which is attached to the body 130.
The surface layer is preferably formed as a single layer in a single coating manufacture
stage. The surface layer is preferably formed around the base layer. The vibration-damping
composite roll coating can be implemented according to the example in FIG. 1 so that
the upper part 111 of the surface layer 110 of the coating 10, where the upper part
extends to a depth of 0.2 to 1 mm from the outer surface 100, is arranged to be harder
than the lower part 112 of the surface layer 110, which serves as the wear surface
of the coating. The border zone between the hard upper part 111 and the softer lower
part 112 has been denoted by the dash-and-dot line 110' extending across the surface
layer. The surface layer 110 is preferably of a single material. The upper part 111
of the surface layer 110 is formed in the radial direction around the lower part 112.
Up to a depth of 0.2 to 1 mm, the upper part 111 of the surface layer 110 of the coating
10 is preferably 15 to 20% harder than the lower part 112 of the surface layer 110.
A preferred first modular gradation of the coating 10 is one where there is a hard
upper part 111 of the surface layer 110, a lower part 112 of the surface layer where
the lower part 112 is softer than the upper part 111, and a base layer 120 which is,
if required (but not necessarily), harder than the lower part 112.
[0049] In FIG. 2, the coating 10 comprises a surface layer 110, whose outer surface is denoted
with reference number 100, a base layer 120 which is attached to the body 130, and
an intermediate layer 115. The intermediate layer 115 is formed between the surface
layer and base layer. Several intermediate layers 115 can be arranged. A preferred
second modular gradation of the coating 10 is one where there is, according to FIG.
2, a hard upper part 111 of the surface layer 110, a lower part 112 of the surface
layer where the lower part 112 is softer than the upper part 111, an intermediate
layer 115 which is, if required (but not necessarily), softer than the lower part
112, and a base layer 120 which is, if required (but not necessarily), harder than
the lower part 112. The intermediate layer 115 is preferably of a material other than
the material of the surface layer 110. According to one embodiment, the intermediate
layer 115 is formed to be harder than the surface layer 110 arranged according to
FIG. 1, where the modular make-up of the surface layer 110 is graded to become softer
from the upper part 111 to the lower part 112. According to yet another embodiment,
the modular make-up of the intermediate layer 115 is graded to be softer than the
surface layer 110. According to yet another embodiment, the intermediate layer 115
is formed to have better thermal conductivity than the surface layer.
[0050] The impacts of the higher thermal conductivity of the inner layers of the coating
10 and the impacts of the potential heating of the internal layers on the vibration
damping properties of the coating are described in more detail in what follows.
[0051] In FIG. 3, the coating 10 comprises a surface layer 110, whose outer surface is denoted
with reference number 100, and a base layer 120, which is attached to the body 130.
The surface layer is formed around/on top of the base layer. The base layer 120 is
formed alternately of a layer 121 made up of a reinforcement comprising continuous
fibers and of a layer 122 made up of a reinforcement comprising discontinuous fibers.
The composite base layer 120 of the coating 10 can be used to improve the vibration
damping of the coating and hence to reduce the occurrence of the barring phenomenon.
The surface layer can be of uniform hardness. In some embodiments, the surface layer
110 can have a modular gradation as illustrated in FIG. 1.
[0052] The maintenance and grinding interval of polymer-coated rolls used in a nip contact
is usually determined by the intensity of the uneven wear of the coating or/and by
the intensity of the increase in the vibration level of the roll. It has been noticed
that as far as vibration is concerned, the increase in the vibration level of a coated
roll can be started from the beginning from a low vibration level, when a thin layer,
typically 0.2 to 1 mm, is ground off the coating. It can be concluded from this that
the intensification of the vibration is due to changes (fatigue) in the material properties
of the surface of the coating and on the other hand due to changes in the surface
shape. In terms of wear, the impact of grinding is trivial.
[0053] The total deformation of the coatings 10 illustrated in FIGS. 1 3 does not change
essentially as compared to a prior art operating coating with equal modules when using
FEM calculation to examine an operating coating where the deformation is the same
(+/-2%) in the tangential direction and in the direction of the thickness of the coating
(direction of thickness = direction of compression, radial direction), but the fatigue
softening of the outer surface 100 of the coating 10, preferably the fatigue softening
of the upper part 111 of the surface layer 110, can be given a significantly longer
operating period due to the higher initial situation.
[0054] FIG. 4 shows on the vertical axis the change in the deformation in the surface layer
in the tangential direction in percentages, and on the horizontal axis the change
in the modulus of elasticity in percentages. FIG. 5 shows on the vertical axis the
change in the deformation in the surface layer in the radial direction in percentages,
and on the horizontal axis the change in the modulus of elasticity in percentages.
FIG. 6 shows on the vertical axis the change in the deformation energy in the surface
layer in percentages, and on the horizontal axis the change in the modulus of elasticity
in percentages. FIGS. 4 - 6 present the first graph 20, the second graph 21, and the
third graph 22, which are examples of three different operating coatings.
[0055] FIGS. 4 - 6 indicate that the deformation in the surface layer 100, 111, which has
softened as little as 5%, and the deformation energy in the surface layer 100, 110
intensify rapidly. At the same time, the softening of the surface layer continues
as a result of fatigue. The secondary benefit of the harder surface is the reduced
deformation energy, which in itself reduces wear and vibration. However, at moduli
of elasticity of the surface in excess of 20%, the deformation begins to focus more
clearly on the lower part 112 of the surface layer 110 and on the inner parts 112;
115; 120 of the coating, in which case the disadvantage might be that when reconditioning
the press element (coating) for example by grinding, it would be necessary to remove
more coating than from prior art operating coatings with equal modules.
[0056] In terms of the damping of vibration and hence in terms of the prevention of the
barring phenomenon, it is advantageous that deformation also takes place in the layer
or layers beneath the outer surface 100.
[0057] Examples of layers beneath the outer surface 100 are the lower part 112 of the surface
layer (FIGS. 1 and 2), intermediate layer 115 (FIG. 2), and base layer 120 (FIG. 3).
In this case, a greater portion of the deformation energy of a nip under load is transmitted
from the outer surface 100 of the surface layer 110 to the underlying layers, and
the permanent deformation in the nip, which leads to barring, can be reduced. With
a suitably selected modular gradation of the layers 110, 115, 120 of the coating 10,
when the coating 10 becomes thinner during its service life as a result of grinding,
the length variation of the nip can be reduced as compared to the use of a prior art
structure where the modulus of elasticity of the coating material increases layer
by layer when moving towards the body 130 of the roll.
[0058] A general guideline presented is that in the surface layer 110 of the coating 10,
the radial (in the direction of compression) modulus of elasticity (hardness) of the
layer beneath the outer surface 100 (or beneath the upper part 111) is adjusted to
a level lower than the radial (in the direction of compression) modulus of elasticity
(hardness) of the outer surface of the surface layer. The higher modulus of elasticity
of the surface layer 110 of the coating 10, in other words the higher modulus of elasticity
of the wear layer, can be arranged in different ways. Moreover and alternatively,
the higher modulus of elasticity of the layers beneath the surface layer 110 can be
arranged in different ways.
[0059] One simple way is the heat treatment of the coating 10 so that the upper part 111
immediately in conjunction with the outer surface 100 of the surface layer 110 (wear
layer) is hardened by "tempering" using heat treatment directed at the outer surface
100, and the heat treatment is repeated in conjunction with grinding (for example
FIGS. 1, 2). This "tempering" can employ a higher temperature directed only at the
outer surface 100 and upper part 111 of the coating 10 than in the original heat treatment
of the surface.
[0060] Another way is to use a coating material which reacts to UV radiation so that the
upper part 111 of the surface layer 110 hardens by itself in normal light, and this
can be intensified by means of separate UV treatment (for example FIGS. 1, 2).
[0061] A third way is to harden the outer surface 100 and the upper part 111 by means of
sol-gel hardening, for example to a thickness of less than 10 µm (for example FIGS.
1, 2).
[0062] A fourth way is to manage the operating conditions of the roll so that the temperature
in the lower part 112 of the surface layer 110 is higher than the temperature in the
outer surface 100 and upper part 111, or the temperature in the inner part 115, 120
of the coating 10 is higher than the temperature in the outer surface 100 and upper
part 111, so that the temperature difference corresponds to the targeted difference
in the modulus of elasticity. As an example, the surface layer 110 of the roll can
be cooled or/and the lower part 112 of the surface layer 110/inner part 115, 120 of
the coating can be heated.
[0063] A fifth way to arrange the structure of the layer beneath the vibration-damping outer
surface 100 is to use a layered structure in the base layer 120, where the layered
structure comprises rigid layers 121 reinforced with continuous fibers alternating
with less rigid layers 122 reinforced with discontinuous fibers (FIG. 3). Such a structure
can retain the strength of the base layer 120 while at the same time increase the
deformation capability of the structure and hence improve vibration damping. The structure
of the vibration-damping composite coating 10 can be manufactured easily by winding
the base layer 120 as a compound structure, where a woven reinforcement comprising
continuous fibers alternates with a mat comprising discontinuous fibers.
[0064] A sixth way to arrange the structure of the layer beneath the vibration-damping outer
surface 100, in addition to the above-described structures, is to use a matrix polymer,
which is suitable in terms of the vibration damping properties, in the layer beneath
the surface layer 110 (for example in the base layer 120, examples in FIGS. 1 and
3), where the matrix polymer can differ from the matrix polymer of the surface layer
110. The matrix polymer of the base layer 120 can have, for example, a lower modulus
of elasticity, and the loss factor (tan d) can be higher than that of the surface
layer 110, in which case the base layer can better absorb deformation energy and thus
dampen vibration.
[0065] In the base layer 120, the conversion of deformation energy into heat is not as big
a problem as in the surface layer 110, because there is better heat conduction in
the base layer than in the surface layer due to the proximity of the metallic roll
body. According to some embodiments, there is better heat conduction in the base layer
than in the surface layer also due to the high fiber content of the layers reinforced
with continuous fibers in the base layer 120 (FIG. 3). Unlike in a functional surface
layer, carbon fiber or heat-conducting fillers can also be used in the base layer
120 to achieve better thermal conductivity. Carbon fiber and heat-conducting fillers
can be used either as separate layers or in the entire base layer structure. The heat-conducting
fillers used can be for example metal particles or aluminum nitride as powder, or
fibers can be treated with metal. Aramid fiber can be used in the base layer 120 to
achieve toughness. Aramid fiber and carbon fiber can be used as a compound structure.
Fiberglass can be used at low cost. The fiberglass can be metallized, for example
nickel-treated or silver-treated to improve thermal conductivity.
[0066] One option for the adjustment of the base layer module or intermediate layer module
lower than the surface layer module is to use flexible particles, such as microspheres,
in the base layer or in the intermediate layer. For example air-filled or gas-filled
glass balls or phenol balls can be mixed into the fiber reinforcement or matrix polymer.
[0067] The above specification provides non-limiting examples of some embodiments of the
invention. It is clear for a professional in the field that the invention is not limited
to the details presented, but the invention can also be implemented using other equivalent
methods. Some features of the presented embodiments can be utilized without the use
of the other features.
[0068] The above specification as such must only be considered as a description of the principles
of the invention, not as a description limiting the invention. The scope of protection
of the invention is hence only limited by the enclosed patent claims.
1. An elastic coating (10) for the rotating press element of a fibre web, in particular
for a roll (9), where the elastic coating comprises a base layer (120) made of a polymer
material fastened on the body (130) of the press element of a fibre web, and a surface
layer (110) made of a polymer material, where the surface layer is formed as a wear
layer on top of the base layer and where the surface layer comprises an outer surface
(100) as the outermost radial point, characterized in that the radial modulus of elasticity of the surface layer (110) beneath the outer surface
(100) of the coating (10) is lower than the radial modulus of elasticity of the outer
surface (100).
2. A coating as claimed in claim 1, characterized in that the polymer material of the surface layer (110) is polyurethane.
3. A coating as claimed in claim 1, characterized in that the polymer material of the surface layer (110) is epoxy.
4. A coating as claimed in any of the claims 1 to 3, characterized in that the radial modulus of elasticity of the base layer (120) is lower than the radial
modulus of elasticity of the outer surface (100).
5. A coating as claimed in any of the claims 1 to 4, characterized in that an intermediate layer (115), which is softer in the radial direction than the surface
layer (110), is arranged between the surface layer (110) and the base layer (120).
6. A coating as claimed in any of the claims 1 to 5, characterized in that the upper part (111) of the surface layer (110), where the upper part (111) extends
to a depth of 0.2 to 1 mm from the surface (100), is arranged to be harder in the
radial direction than the lower part (112) of the surface layer (110), where the lower
part (112) is radially beneath the upper part (111).
7. A coating as claimed in any of the claims 1 to 6, characterized in that the upper part (111) of the surface layer (110) is hardened by means of heat treatment
directed at the upper part.
8. A coating as claimed in any of the claims 1 to 7, characterized in that a component or additive which reacts to UV radiation is added to the polymer material
of the surface layer (110) and the surface layer is hardened by UV radiation.
9. A coating as claimed in any of the claims 1 to 8, characterized in that the surface (100) of the surface layer (110) is hardened by sol-gel hardening.
10. A coating as claimed in any of the claims 1 to 9, characterized in that the base layer (120) is arranged as a layered structure, where rigid layers (121)
reinforced with continuous fibers alternate with less rigid layers (122) reinforced
with discontinuous fibers.
11. A coating as claimed in any of the claims 1 to 10, characterized in that the layer (115, 120) beneath the surface layer (110) is provided with a matrix polymer,
which has a lower modulus of elasticity and a higher loss factor than the surface
layer.
12. A coating as claimed in any of the claims 1 to 11, characterized in that the thermal conductivity of the layer (115, 120) beneath the surface layer (110)
is higher than the thermal conductivity of the surface layer.
13. A coating as claimed in any of the claims 1 to 12, characterized in that carbon fiber or heat-conducting fillers are used in the layer (115, 120) beneath
the surface layer (110) to achieve a better thermal conductivity.