FIELD OF APPLICATION

The present invention relates to a roll for industrial processes, a method and apparatus for producing the same. The aforesaid roll can be applied, for example but without limits to generality, in the production field of metal products in which hot and/or cold rolling, straightening, yielding, towing or guiding thereof is required.

BACKGROUND ART

Rolls are known to be used in many industrial processes such as, for example, the production of metal products where cold and/or hot rolling, forming, straightening, yielding, towing or guiding of the metal products themselves is required.

Typically, the known rolls are made of materials having a high hardness such as, for example, hardened steels for tools, sintered carbide materials or Cermet.

It is also known to coat the aforesaid rolls with a coating layer having a higher hardness with respect to that of the roll itself, such as, for example, a layer of carbide, nitride and/or carbonitride which is deposited by PVD (Physical Vapour Deposition) techniques. The coatings deposited using PVD techniques, although having high hardness, have a limited duration in time, as their thickness normally does not exceed 4 pm. Such a limitation occurs because otherwise, the coating layer would be unstable and not very strong. In fact, the Applicant has experimentally found that a thin film deposited through PVD techniques grows with the intrinsic stresses typical of the technique itself (generally based on magnetron sputtering, cathodic arc, evaporation) and the method parameters maintained during the deposition such as temperature, working pressure, deposition rate, applied bias (see for example Thornton, J. A., "Stress-Related Effects In Thin Films", Thin Solid Films, 171 (18989) 5-31. If not controlled, the intrinsic stress increases as a function of the deposited thickness, this means that increasing the reported thickness can result in the detachment of the thin film from the supporting substrate or in the breakage of the coating itself. This represents a limit in the growth of coatings made with thin film, but with relevant thickness, as explained above. To overcome this limitation, in the prior art the most common approach is to intersperse layers of different materials in order to discharge the energy due to the intrinsic stress in each interface. With this approach, if for example a crack inside the thin film were to break, this would attenuate, losing energy at each interface encountered until it stops completely, avoiding the breakage of the coating. However, interspersing layers of different materials can have limitations or disadvantages in the art or in the different applications, not least in terms of production times and costs.

It is also known that the wear, generated by the friction and adhesion phenomena in contact with the product they process, reduces the useful life of the known rolls early, which tend to lose their geometric features, finishing and surface coating, consequently also worsening the final quality of the product itself.

Examples of known deposition methods of materials by means of PVD techniques are described in US 2013/302596 Al, US 2019/226075 Al and EP 2 628 817 Al.

There is therefore a need to improve a roll for industrial processes and the related method and apparatus for producing the same, which can overcome at least one of the drawbacks of the prior art.

To do this, it is necessary to solve the technical problem of increasing the useful life of the roll and improving its resistance to wear.

In particular, an object of the present invention is to provide a roll for industrial processes having a high surface hardness.

Another object of the present invention is to provide a roll for industrial processes which makes it possible to reduce the friction between it and the processed product.

A further object of the present invention is to provide a roll for industrial processes which makes it possible to reduce adhesion phenomena in contact with the material of the processed product.

A further object of the present invention is to provide a roll for industrial processes allowing the final quality of the processed product to be improved and kept constant over time.

In order to overcome the drawbacks of the prior art, and to obtain the above as well as further objects and benefits, the Applicant has studied, tested and realized the present invention.

DISCLOSURE OF THE INVENTION

The present invention is expressed and characterised in the independent claims. The dependent claims show other features of the present invention or variants of the main solution proposed.

In accordance with the aforesaid objects and to solve the aforesaid technical problem in a new and original manner, also obtaining considerable advantages with respect to the prior art, a roll for industrial processes is provided with a central body on which a surface coating is disposed. Said coating comprises an adhesion layer of a first adhesion material disposed in contact with the external surface of the aforesaid central body, a central core, comprising a plurality of first intermediate layers of a first intermediate material and a plurality of second intermediate layers of a second intermediate material and disposed above the aforesaid adhesion layer, and a work layer of a work material disposed above the aforesaid central core.

The central core is thus formed by a succession of layers. This makes it possible to control the intrinsic stress of each layer and cause the layered structure to substantially self-support without collapsing. It is therefore advantageously possible to achieve a thickness of the surface coating of the roll greater than that currently envisaged for the rolls, as said about 4 pm, without the structure of the coating collapsing.

In possible embodiments, the multilayer structure of the central core is also free of nitride oxides.

According to another aspect of the present invention, the aforesaid coating has a total thickness greater than 8 pm, preferably comprised between about 10 pm and about 150 pm and is obtained by at least one of a PVD, CVD (Chemical Vapour Deposition) and PECVD (Plasma Enhanced Chemical Vapour Deposition) technique.

According to another aspect of the present invention, the ratio of the thickness of the aforesaid adhesion layer to the aforesaid total thickness is comprised between about 0.005 and about 0.015, preferably it is about 0.01, the ratio of the thickness of the aforesaid central core and the aforesaid total thickness is comprised between about 0.95 and about 0.97, preferably it is about 0.96, and the ratio of the thickness of the aforesaid work layer and the aforesaid total thickness is comprised between about 0.03 and about 0.05, preferably it is about 0.04.

According to another aspect of the present invention, the aforesaid first intermediate layers and the aforesaid second intermediate layers are disposed alternated one on top of the another and each of them has a thickness comprised in an interval that ranges from about 1 nm to about 4 pm.

According to another aspect of the present invention, the hardness of the aforesaid adhesion layer is lower than the hardness of the aforesaid central core which is lower than the hardness of the aforesaid work layer.

The present invention also relates to a method to produce a roll provided with a central body on which a surface coating is disposed.

According to a further aspect of the present invention, the method comprises at least the following steps:

- a preparation step in which a central body is disposed inside a treatment chamber;

- a first deposition step in which first deposition means are activated to deposit an adhesion layer of an adhesion material on the aforesaid central body by means of at least one of a PVD, CVD and PECVD technique;

- a second deposition step in which second deposition means are activated to deposit a central core comprising at least one layer of a first intermediate material on the aforesaid adhesion layer by means at least one of a PVD, CVD and PECVD technique, in which said central core comprises a plurality of first intermediate layers of a first intermediate material and a plurality of second intermediate layers of a second intermediate material; and

- a third deposition step in which third deposition means are activated to deposit a work layer of a work material on the aforesaid central core by means of at least one of a PVD, CVD and PECVD technique.

According to another aspect of the present invention, the aforesaid second deposition step also provides to activate fourth deposition means, in alternation with the aforesaid second deposition means, to also deposit at least one layer of a second intermediate material, by means of at least one of a PVD, CVD and PECVD technique.

According to another aspect of the present invention, the method further comprises a temperature conditioning step in which the aforesaid treatment chamber is brought to a temperature comprised between about 350 °C and about 500 °C and a pressure conditioning step in which the aforesaid treatment chamber is brought to a pressure comprised between about 10' ³ mbar to about 10' ² mbar.

According to another aspect of the present invention, at least one of the aforesaid deposition means is of the cathodic arc type and the method further comprises a power supply step in which the aforesaid at least one deposition means of the cathodic arc type is powered with a current comprised between about 20 A and about 200 A.

According to another aspect of the present invention, at least one of the aforesaid deposition means is of the magnetron type and the method further comprises a power supply step in which the aforesaid at least one deposition means of the magnetron type is powered with a power comprised between about 10 W/inch ² and about 100 W/inch ² .

The present invention also relates to an apparatus for producing a roll provided with a central body on which a surface coating is disposed, which comprises a treatment chamber configured to contain the aforesaid central body therein and in which there is disposed a source of an adhesion material associated with deposition means configured to deposit an adhesion layer of the aforesaid adhesion material on the aforesaid central body by means of at least one of a PVD, C VD and PECVD technique, a source of a first intermediate material associated with deposition means which are configured to deposit a central core, formed by a plurality of first intermediate layers of a first intermediate material and a plurality of second intermediate layers of a second intermediate material by means of at least one of a PVD, CVD and PECVD technique and a source of a work material associated with deposition means which are configured to deposit a work layer of the aforesaid work material on the aforesaid central core by means of at least one of a PVD, CVD and PECVD technique.

According to another aspect of the present invention, the apparatus comprises a source of a second intermediate material associated with deposition means which are configured to deposit at least one layer of the aforesaid second intermediate material on the aforesaid at least one layer of the aforesaid first intermediate material, by means of at least one of a PVD, CVD and PECVD technique. According to another aspect of the present invention, the apparatus comprises temperature conditioning means configured to bring the aforesaid treatment chamber to a temperature comprised between about 350° C and about 500° C, and pressure conditioning means configured to bring the aforesaid treatment chamber to a pressure comprised between about 10’ ³ mbar and about 10' ² mbar.

According to another aspect of the present invention, at least one of the aforesaid deposition means is of the cathodic arc type and at least one other of the aforesaid deposition means is of the magnetron type.

According to another aspect of the present invention, the aforesaid deposition means are of the cathodic arc type.

According to another aspect of the present invention, the aforesaid deposition means are of the magnetron type.

In embodiments, combinable with all the embodiments described herein, the aforesaid first intermediate material and the aforesaid second intermediate material are the same or different.

ILLUSTRATION OF THE DRAWINGS

These and other aspects, features and advantages of the present invention will become clear from the following disclosure of some embodiments, provided merely by way of non-limiting example, with reference to the accompanying drawings in which:

- fig. 1 is a sectional view of a part of a roll for industrial processes, according to the present invention;

- fig. 2 is a sectional schematic view of an apparatus according to the present invention;

- fig. 3 is an electric diagram of the apparatus of fig. 2;

- fig. 4 is a graph depicting the correlation between the thickness and the resistance to wear of some coatings according to the prior art (expressed in number of cycles to be performed before reaching a coating breakage percentage);

- figs. 5 and 6 are two graphs depicting the correlation between the thickness and the resistance to wear of some coatings in accordance with the present invention (expressed in metres travelled per unit of volume removed).

It should be noted that, in the present disclosure, the phraseology and terminology used, as well as the figures in the accompanying drawings, even as disclosed, have the sole purpose of illustrating and explaining the present invention, since their function is illustrative and not limited to the invention itself, the scope of protection thereof being defined by the claims.

To facilitate understanding, identical reference numbers have been used, where possible, to identify identical common elements in the figures. It should be noted that elements and features of an embodiment can be conveniently combined or incorporated into other embodiments without further clarification.

DESCRIPTION OF EMBODIMENTS

With reference to figure 1, a roll 10 for industrial processes according to the present invention, comprises a central body 11, in the form of a rotation solid, on which a surface coating 12 is disposed.

The material of the central body 11 can be chosen according to the use of the roll 10, for example in a group comprising steels for tools for cold processes, for example W.Nr. 1.2379, W.Nr. 1.2080, tool steels for hot processes, for example W.Nr. 1.2344, W.Nr. 1.2343, W.Nr. 1.2367, W.Nr. 1.2365, high speed steels, for example W.Nr. 1.3343, steels obtained by means of powder metallurgy, bronze- aluminium alloys, sintered such as tungsten carbide, silicon carbide or ceramic materials.

According to an aspect of the present invention, the coating 12 comprises at least one adhesion layer 15, a central core 16, and a work layer 17.

In embodiments, the central core 16 is formed by a multilayer structure, which is formed by the repetition in succession of monolayers made in sequence, so as to control the intrinsic stress of each layer and cause the multilayer structure to self- support without collapsing. The coating 12 has a total thickness S greater than 8 pm, preferably comprised between about 10 pm and about 150 pm and is obtained by means of PVD (Physical Vapour Deposition), or CVD (Chemical Vapour Deposition) or still PECVD (Plasma Enhanced Chemical Vapour Deposition) technique, as will be described in detail below.

The Applicant has found that the production, by means of said techniques, of the coating 12 as indicated above, in particular of the multilayer structure of the central core 16, allows to obtain a coating of significant thickness, since it envisages controlling the stress of the single deposited layer (it is thereby possible to possibly also always work with the same material), defining the method parameters maintained during the deposition, such as for example temperature, working pressure, deposition rate, applied bias, so as to minimise the intrinsic stress of the thin film forming the coating 12. Generally, the intrinsic stress is measured with Stoney's equation on a test sample. In fact, for the quantification of the intrinsic stresses of the deposited thin film, Stoney's empirical formula can be used by measuring the induced curvature variation (convex and concave respectively for tensile and compressive stress) from the thin film deposited on a Si wafer (reference substrate). See for example, Wang, S. et al. http://dx.doi.Org/10.1016/j.apsusc.2014.l 1, 130 and Gan, B. K. Et al doi: 10.1063/1.1640462#.

In addition, if it is not possible to completely eliminate the stress of the single layer, the present invention makes it possible to deposit successive layers (of the same material or of different materials) with opposite intrinsic stresses, so as to eliminate the overall effect on the final structure of the grown film.

The adhesion layer 15 is disposed in contact with the external surface of the central body 11 and supports the central core 16 which, in turn, supports the work layer 17.

The adhesion layer 15 is formed from an adhesion material Ml configured to adhere to the external surface of the central body 11 and is therefore selected based on the material of which the central body 11 is formed.

For example, but without this being interpreted as a limitation, if the central body 11 is steel, the adhesion material Ml can be titanium, or chromium. Alternatively, if the central body 11 is Cermet, the adhesion material Ml can be titanium nitride (TiN) or chromium nitride (CrN).

The choice of the adhesion material Ml is made according to the material of the central body 11 on which the coating 12 is to be deposited and the material of the central core 16. In particular, the adhesion layer 15 acts as an intermediate layer connecting the central body 11 and the central core 16.

The ratio between the thickness SI of the adhesion layer 15 and the total thickness S of the coating 12 varies in an interval comprised between about 0.005 and about 0.015, preferably it is about 0.01.

Furthermore, the hardness DI of the adhesion layer 15 is advantageously greater than the hardness DO of the central body 11. The central core 16 is disposed above the adhesion layer 15 and is configured to support the work layer 17 and also to confer toughness to the coating 12 itself.

The central core 16 comprises, in turn, a plurality of intermediate layers 18, 19 disposed alternated one on top of another. In particular, the central core 16 can include a plurality of intermediate layers 18 and a plurality of intermediate layers 19. The plurality of intermediate layers 18 is disposed alternated with the plurality of intermediate layers 19 and, for example, said plurality of intermediate layers 18 and of intermediate layers 19 can be repeated alternated one on top of the other. For example, a minimum structure of the central core 16 can envisage a bi-layer structure of intermediate layers 18 (i.e., two intermediate layers 18) alternated with a bi-layer structure of intermediate layers 19 (i.e., two intermediate layers 19). Such a structure can be repeated with successive alternation of bi-layers of intermediate layers 18 and bi-layers of intermediate layers 19.

In possible embodiments, the multilayer structure of the central core 16 is also free of nitride oxides.

The material of the central core 16 is chosen both as a function of the workplace, for example if the latter is dry, lubricated, at temperature or in the presence of corrosive atmospheres, and according to the material of the product P to be processed by means of the roll 10.

According to possible embodiments, the aforesaid first intermediate material M2 and the aforesaid second intermediate material M3 are the same or different.

In a possible example, without this constituting a limitation of the scope of protection, first intermediate layers 18 are made of a first intermediate material M2 and second intermediate layers 19 are made of a second intermediate material M3.

By way of non-limiting example, the first intermediate material Ml and the second intermediate material M2 can be different from each other and chosen from a group comprising transition metal borides, oxides, carbides, nitrides and/or carbonitrides such as: Titanium, Vanadium, Chromium, Cobalt, Zirconium, Niobium, Molybdenum, Hafnium, Tantalum and Tungsten.

Purely by way of non-limiting example, the borides can be Boron Nitride (BN) and Boron Carbide (B4C). The oxides can be Alumina, Titania, Zirconia, etc. possibly also comprising possible nano dispersions of metals, semi-metals or non- metals, for example Cu, diamond, Si, silica or self-lubricating sulphides. Furthermore, the thickness Si of each intermediate layer 18, 19 is comprised in an interval which ranges from about 1 nm to about 4 pm.

In other embodiments, the intermediate layers 18, 19 are made of the same material, possibly deposited with different techniques. Alternatively, the intermediate layers 18, 19 can also be made of more than two different materials between one layer and the other, for example three or four, and the alternation of the layers having different materials can be ternary, quaternary, or yet another.

The presence and disposition of the intermediate layers 18, 19, and possibly the choice of the materials of the intermediate layers 18, 19, allows to adjust the overall chemical/physical properties of the coating 12 according to the final application of the roll 10, giving it a high structural stability and favourably to obtain high final thicknesses. In particular, the fact of producing the central core 16 is produced as a structure of intermediate layers 18, 19, allows a control of the residual intrinsic stress of the single layer and therefore of the overall coating, allowing to produce a structure which is self-supporting and thus obtain high thickness.

Consequently, the structure of the central core 16 with intermediate layers 18, 19 allows the coating 12 to be made by at least one of a PVD, CVD and PECVD technique, also reaching a high total thickness S, without the layers 15, 16, 17, 18 collapsing on top of each other.

This allows to obtain, by means of at least one of a PVD, CVD and PECVD technique, a coating 12 with a thickness greater than 8 pm and provided with high toughness and resistance to wear.

The ratio between the thickness S2 of the central core 16 and the total thickness S of the coating 12 varies in an interval comprised between about 0.95 and about 0.97, preferably it is about 0.96. The hardness D2 of the central core 16 is advantageously greater than the hardness DI of the adhesion layer 15 and also the hardness DO of the central body 11.

The work layer 17 is disposed above the central core 16 and is made of a work material M4 configured to contact, in use, the product which the roll 10 processes. The work material M4 is chosen according to the material with which the product to be processed is made to ensure a high slidability, i.e., a reduced friction therewith, and also to avoid, or at least reduce, the phenomena of contact adhesion and the wear between the product to be processed and the work layer. Purely by way of non-limiting example, in the case in which the material of the product to be processed is Fe-based, the work material M4 is ZrN.

The ratio between the thickness S3 of the work layer 17 and the total thickness S of the coating 12 is comprised in an interval between about 0.03 and about 0.05, preferably it is about 0.04.

The hardness D3 of the work layer 17 is advantageously greater than the hardness D2 of the central core 16, the hardness DI of the adhesion layer 15 and also the hardness DO of the central body 11. It should be noted that such a conformation confers on the roll 10 a gradient of increasing hardness towards the exterior thereof, which allows to increase the useful life of the roll 10.

Merely by way of example, the graph in fig. 4 depicts two curves which relate the thickness of a known type of coating of a roll with the number of rotations which the same makes before reaching a certain breakage probability of the coating itself.

Curve A depicts the relationship between the thickness of a coating according to the prior art and the number of rotations which a roll provided with the coating performs before reaching 5% breakage probability of the coating. Curve B depicts the relationship between the thickness of a coating according to the prior art and the number of rotations which a roll provided with the coating performs before reaching 10% breakage probability.

From the graph of figure 4 it is evident that an increase in the thickness of the known type of coating corresponds to a decrease in its wear resistance, understood as the number of revolutions to be carried out to achieve the breakage probability of the coating.

In addition, the Applicant has conducted some experimental tests to evaluate the wear resistance of a coating 12 in accordance with the present invention, the results of which will be set out below by way of example not to be considered limiting. In particular, figure 5 is a graph which relates the thickness of a coating 12, in accordance with the present invention, applied to a steel no. 1.2379, with the inverse of the wear rate WR' ¹ of the same coating 12, expressed in N*mm/pm ³ .

Instead, figure 6 is a graph which relates the thickness of a coating 12, according to the present invention, applied to a steel no. 1.2344, with the inverse of the wear rate WR' ¹ of the same coating 12, expressed in N*mm/pm ³ . The curves C and D refer to tests conducted at 40N while the curves E and F refer to tests conducted at 80N. For the tests conducted at 40N, no failure rate emerged, with the tests at 80N a failure rate of 1.96% was detected.

From the aforesaid graphs of figures 5 and 6 it is clear that as the thickness S of the coating 12 increases the number of cycles increases, i.e., the metres travelled by the same, per unit of volume removed, contrary to what happens for the coatings of the prior art.

With reference to figures 2 and 3, the present invention also relates to an apparatus 50 for producing a roll 10 according to the present invention, which comprises a treatment chamber 51 configured to contain the central body 11 therein.

In the treatment chamber 51 there is disposed a source 52 of the adhesion material Ml associated with respective deposition means 53 configured to deposit the adhesion layer 15 on the central body 11 by means of at least one of a PVD, CVD and PECVD technique.

Furthermore, a source 55 of the first intermediate material M2 and a source 57 of the second intermediate material M3 are also disposed in the treatment chamber, each of which is associated with respective deposition means 56, 58 configured to deposit the central core 16 on the adhesion layer 15 by means of at least one of a PVD, CVD and PECVD technique.

In particular, the central core 16 comprises first intermediate layers 18 and second intermediate layers 19 and the deposition means 56 associated with the source 55 of the first intermediate material M2 are configured to deposit the first intermediate layers 18, while the deposition means 58 associated with the source 57 of the second intermediate material M3 are configured to deposit the second intermediate layers 19.

In addition, a source 59 of the work material M4 associated with respective deposition means 60 configured to deposit the work layer 17 on the central core 16 by means of at least one of a PVD, CVD and PECVD technique is also disposed in the treatment chamber 51.

Each deposition means 56, 58, 59, 60 can be of the cathodic arc type or of the magnetron type, as a function of the features which are to be conferred on the respective layer 15, 17, 18, 19. For example, a deposition means of the magnetron type can be used when low melting materials are deposited, so as to limit the presence of macro-particles and obtain a flatter surface, while a deposition means of the cathodic arc type is used to obtain high density films.

Merely by way of non-limiting example, deposition means of the cathodic arc type can be used to deposit a CrN layer. Or, in another non-limiting example, deposition means of the magnetron type can be used to deposit an AlTiN layer.

In a first embodiment, the apparatus 50 comprises two deposition means of the cathodic arc type and two deposition means of the magnetron type.

In a second embodiment, the apparatus 50 comprises three deposition means of the cathodic arc type and one deposition means of the magnetron type.

In a third embodiment, the apparatus 50 comprises one deposition means of the cathodic arc type and three deposition means of the magnetron type.

In a fourth embodiment, the apparatus 50 comprises four deposition means of the cathodic arc type.

In a fifth embodiment, the apparatus 50 comprises four deposition means of the magnetron type.

Furthermore, the operation of each deposition means 56, 58, 59, 60 is controlled by a control unit 69, for example of the programmable type.

The apparatus 50 further comprises biasing means 65, also controlled by the control unit 69, configured to bias the central body 11 disposed inside the treatment chamber 51 by applying thereto a voltage comprised between about -400 V and 0 V in direct current DC and/or in pulsed direct current PDC.

By way of non-limiting example, the bias voltage is regulated in pulsed direct current PDC when the material of the central body 11 is not perfectly conductive, for example in the case in which the central body 11 is made of Cermet. Furthermore, the pulsed direct current PDC regulation allows for denser coatings with respect to what can be obtained with a standard direct current DC regulation, and avoids the excessive overheating of the roll 10. Direct current DC regulation is used in the case in which the central body material is perfectly conductive.

The apparatus 50 fiirther comprises pumping means 66, controlled by the control unit 69, and configured to bring the treatment chamber 51 to a pressure comprised between about 10' ³ mbar and about 10‘ ² mbar. The apparatus 50 also comprises conditioning means 67, controlled by the control unit 69, and configured to heat the interior of the treatment chamber 51 to a temperature comprised between about 300° C and about 600° C, preferably between about 350° C and about 500° C.

The operation of the apparatus 50 just described, which corresponds to the method according to the present invention, comprises the following steps.

The central body 11 on which the coating 12 is to be disposed is disposed inside the treatment chamber 51 of the apparatus 50.

Then, the control unit 69 activates the pumping means 66 and the conditioning means 67 to bring the treatment chamber 51 to a temperature comprised between about 350 °C and about 500 °C and to a pressure comprised between about 10’ ³ mbar and about 10' ² mbar.

Next, the control unit 69 activates the deposition means 53 associated with the source 52 of the adhesion material Ml to deposit the adhesion layer 15 on the central body 11 by means of at least one of a PVD, CVD and PECVD technique.

Then, the control unit 69 activates the deposition means 56, 58 associated with the source 55 of the first intermediate material M2 and the source 57 of the second intermediate material M3, to deposit the central core 16 on the adhesion layer 15 by means of at least one of a PVD, CVD and PECVD technique.

In particular, the deposition means 56 associated with the source 55 of the first intermediate material M2 are activated in alternation with the deposition means 58 associated with the source 57 of the second intermediate material M3 to deposit a plurality of first intermediate layers 18 and second intermediate layers 19 disposed alternated one on top of the other.

This allows to obtain a central core 16 with greater thickness and mechanical and tribological properties than could be achieved with the deposition of a single layer of deposited material with any known deposition technology. Finally, the control unit 69 activates the third deposition means 60 to deposit the work layer 17 on the central core 16 by means of at least one of a PVD, CVD and PECVD technique.

In the case in which the deposition means are of the cathodic arc type, they are powered with a current comprised between about 20 A and about 200 A.

In the case in which the deposition means are of the magnetron type, they are powered with a power comprised between about 10 W/inch ² and about 100 W/inch ² .

It is clear that modifications and/or additions of parts can be made to the roll 10 for industrial processes, the apparatus 50 and the method disclosed herein, without departing from the scope of the present invention as defined by the claims. It is also clear that, although the present invention has been described with reference to some specific examples, a person skilled in the art will be able to make many other equivalent forms of rolls for industrial processes having the features expressed in the claims and therefore all of which falling within the scope of protection defined thereby. In the following claims, the references in parentheses have the sole purpose of facilitating reading and must not be considered as limiting factors of the scope of protection defined by the claims themselves.