Saw Blade or Other Cutting Tool Comprising a Coating

Abstract

A cutting tool comprises a coating on a substrate. The coating comprises a first layer element having an overall composition comprising the metal or metalloid elements aluminum, chromium, titanium, and silicon. The first layer element comprises at least 2 N.sub.lay first layer element layers. Each of the first layer element layers comprises a nitride layer comprising the metal or metalloid elements aluminum, chromium, titanium and silicon. The N.sub.lay first layer element layers comprise at least two different types of layers that at least differ in a silicon content. A first type of the layers has a highest silicon content C.sub.Si,H, (in at. %) and a second type of the layers has a lowest silicon content C.sub.Si,L (in at. %), both relative to a total of the metal and metalloid elements, and with a ratio of the lowest silicon content C.sub.Si,L to the highest silicon content C.sub.Si,H in the range of 0.25≤C.sub.Si,L/C.sub.Si,H≤0.9.

Claims

1. A cutting tool comprising a coating on a substrate, wherein the coating comprises a first layer element, wherein the first layer element has an overall composition comprising the metal or metalloid elements aluminum, chromium, titanium, and silicon, wherein the first layer element comprises a number N.sub.lay of first layer element layers, wherein N.sub.lay is at least 2, wherein each of the first layer element layers comprises a nitride layer comprising the metal or metalloid elements aluminum, chromium, titanium and silicon, wherein the N.sub.lay first layer element layers comprise at least two different types of layers, wherein the different types of layer at least differ in a silicon content, wherein a first type of the layers has a highest silicon content C.sub.Si,H (at. %), relative to a total of the metal and metalloid elements, and wherein a second type of the layers has a lowest silicon content C.sub.Si,L (at. %), relative to a total of the metal and metalloid elements, wherein a ratio of the lowest silicon content C.sub.Si,L to the highest silicon content C.sub.Si,H is selected from the range of 0.25≤C.sub.Si,L/C.sub.Si,H≤0.9; wherein a thickness of the first layer element is selected from the range of 1-12 μm; wherein in the first layer element, relative to a total of the metal and the metalloid elements aluminum is available in the range of 72-77 at. %, titanium is available in the range of 5-11 at. %, chromium is available in the range of 13-20 at. %, and silicon is available in the range of 0.7-1.7 at. %.

2. The cutting tool according to claim 1, wherein the ratio of the lowest silicon content C.sub.Si,L to the highest silicon content C.sub.Si,H is selected from the range of 0.4≤C.sub.Si,L/C.sub.Si,H≤0.6.

3. The cutting tool according to claim 1, wherein C.sub.Si,H≤1.7 and C.sub.Si,L≤1.

4. The cutting tool according to claim 1, wherein the first layer elements layers have a first layer element layer thickness in the range of 0.1-0.5 μm.

5. The cutting tool according to claim 1, wherein in each of the first layer element layers a combination of titanium and chromium is available in the range of 21-27 at. % relative to a total of the metal and the metalloid elements.

6. The cutting tool according to claim 1, wherein the plurality of first layer element layers comprise a number subs.sub.N of stacked subsets of the first layer elements layer, wherein subs.sub.N is at least 2, and wherein each of the subsets comprises the first type of the layers and the second type of the layers, wherein a subset thickness of each of the subsets is equal to or smaller than 1 μm.

7. The cutting tool according to claim 6, wherein at least one of the subsets of the stacked subsets comprises at least three different types of first layer element layers.

8. The cutting tool according to claim 1, wherein a thickness of the first layer element is selected from the range of 2-7 μm.

9. The cutting tool according to claim 1, wherein the coating further comprises (i) a base layer element arranged between the substrate and the first layer element and/or (ii) a top layer element arranged over the first layer element, wherein a base layer element thickness of the base layer element is selected from the range of 0.2-1.2 μm, wherein the base layer element comprises one or more base layer element layers, wherein base layer element layers comprises a nitride layer comprise chromium nitride and/or aluminum-chromium-nitride; and wherein a top layer element thickness of the top layer element is selected from the range of 0.2-1.2 μm, wherein the top layer element comprises one or more top layer element layers, wherein top layer element layers comprises (i) a nitride layer comprising chromium and/or aluminum or (ii) a carbonitride layer comprising chromium and/or aluminum; and where a total coating thickness of the coating is selected from the range of 3-8 μm.

10. The cutting tool according to claim 9, comprising the base layer element, wherein the base layer element comprises a plurality of base layer element layers, wherein an aluminum content of an upper base layer element layer configured closest to the first layer element is higher than the aluminum content in a lower base layer element layer configured closest to the substrate.

11. The cutting tool according to claim 1, wherein the cutting tool is a circular saw blade, a tool bit, a router bit, or a drill.

12. A coating as defined in claim 1 configured at a substrate (5).

13. A method for producing a cutting tool comprising a coating according to claim 1, by physical vapor deposition, the method comprising: providing a substrate into a vacuum chamber of a physical vapor deposition oven, wherein the chamber comprises a number Cat.sub.N of metal cathodes, wherein Cat.sub.N is at least 3, wherein at least a subset of the number Cat.sub.N of metal cathodes together comprise the metal or metalloid elements aluminum, chromium, titanium, and silicon, and depositing the coating at the substrate by physical vapor deposition, wherein (i) a nitrogen comprising gaseous fluid and optionally (ii) a carbon comprising gaseous fluid is provided in the vacuum chamber, while rotating the substrate, wherein the coating is deposited layer-by-layer, to provide the coating.

14. The method according to claim 13, wherein (i) at least one of the metal cathodes comprises the metal or metalloid elements aluminum, titanium, and silicon, and wherein at least another one of the metal cathodes comprises the metal elements aluminum and chromium or wherein (ii) at least one of the metal cathodes comprises the metal elements aluminum, chromium, and silicon, and wherein at least another one of the metal cathodes comprises the metal elements aluminum and titanium, and wherein the during deposition, a variable evaporation current is provided to the metal cathodes.

15. The method according to claim 13, wherein at least one of the metal cathodes comprises silicon, and wherein the at least one metal cathode comprising silicon is arranged adjacent to another one of the metal cathodes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0095] FIG. 1 schematically depict an embodiment of a tool according to the invention;

[0096] FIGS. 2 and 3 schematically depicts some aspects of the coating;

[0097] FIGS. 4-5 schematically depict some further aspects of the invention.

[0098] The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0099] In FIG. 1, a saw blade is depicted as an embodiment of an article/cutting tool 1 of the invention. The tool 1 comprises a coating 10 on a substrate 5, especially a tribological coating. The coating 10 may only partly cover the substrate 5. In other embodiments, the coating may cover the entire of the exterior side(s) 4 of the substrate 5. The coating 10 comprises a first layer element 20, having an overall composition comprising the metal elements aluminum, chromium, titanium, and silicon. The first layer element 20 of FIG. 1 comprises two stacked first layer element layers 21. Any first layer element layer 21 may comprise a nitride layer which is also indicated herein as (AlCrTiSi)N.

[0100] In embodiments of the first layer element 20, Al is especially available with at least 68 at. % and especially at maximum 80 at. %, Si is especially available in the range of 0.5-2 at. %, Ti is especially available with at least 4 at. %, and Cr is especially available with a maximum of 20 at. %; all relative to the total of the metal elements (in the first layer element 20). Herein, this may also be indicated by the first layer element 20 comprises Al.sub.aCr.sub.bTi.sub.cSi.sub.d, especially wherein 0.68≤a≤0.80, especially wherein b≤0.2; especially wherein c≥0.04, and especially wherein 0.005≤d≤0.02. In further embodiments of the first layer element 20 0.72≤a≤0.77; 0.13≤b≤0.2; 0.05≤c≤0.11; and 0.007≤d≤0.017.

[0101] The coating 10 comprises a coating thickness 15 that is defined in FIG. 1 by a thickness 25 of the first layer element 20, a base layer element thickness 35 and a top layer element thickness 45. It is noted that these respective layer elements 10, 20, 30, and 40 not necessarily are present in all embodiments. The thickness 25 of the first layer element 20 (or “first layer element thickness” 25 may especially be in the range of 1-12 μm, such as 2-7 μm. The first layer element thickness 25 may e.g. be in the range of 1-4 μm, such as 1-2.5 μm for a mono layer, i.e. wherein the first layer element 20 comprises a single first layer element layer 21 or a plurality of first layer element layers 21 with the same or especially different composition. The thickness 25 of the first layer element 20 may in further embodiments be in the range of e.g. 3-7 μm

[0102] Furthermore, the coating thickness 15 may in embodiments be 3-8 μm. In further embodiments, the coating thickness may be in the range of 1-3 μm. Both the top layer element thickness 45 and the base layer element thickness 35 may especially be in the range of 0.05-1.5 μm, such as 0.2-1.2 μm. The top layer element thickness 45 may in embodiments be smaller (or larger) than the based layer element thickness 35. In embodiments the top layer element thickness 45 is in the range of 0.05-0.3 μm. In further embodiments, the base layer element thickness 35 is in the range of 0.3-1 μm.

[0103] The base layer element 30 may comprise one or more base layer element layers 31, e.g., comprising nitride layers, such as comprising CrN or AlCrN. The top layer element 40 may (also) comprise one or more top layer element layers 41, especially any one of these top layer element layers 41 comprising a nitride layer or a carbonitride layer, such as an AlN, CrN, ALCrN, AlCN, CrCN, or AlCrCN layer.

[0104] The coating 10 may further comprise an intermediate layer element 50 comprising an intermediate layer element layer 51, as is depicted in FIG. 2. The intermediate layer element 50 is especially arranged between two of first layer elements 20. The intermediate layer element layer 51 especially comprises a nitride layer comprising one or more of the metal elements aluminum, titanium and chromium, especially AlTiN, CrN or AlCrN. Two first layer elements 20 may also be stacked without having an intermediate layer element 50 in between. It will further be appreciated that the coating 10 may further comprise further layer (elements) at any location in the coating.

[0105] Herein the terms “top” “upper”, “higher”, “above”, “over”, etc. in relation to the coating 10 may especially refer to a location most (or further) remote from the substrate 5 (with respect to another location). Likewise the terms “base”, “lower” “under” and the like may be located closer or closest to the substrate 5.

[0106] In FIG. 3, an embodiment of a coating 10 is depicted in further detail. The embodiment comprises the base layer element 30 comprising a plurality of base layer element layers 31. The arrangement of the plurality of base layer element layers 31 is especially configured to improve the adherence of the first layer element 20 to the substrate 5. For that, the aluminum content of the upper base layer element layer 319 (contacting the first layer element 20) may be higher than the aluminum content in the lower base layer element layer 311 (contacting the substrate 5). Moreover the aluminum content of successive base layer element layers 31 stacked on top of each other in a direction from the substrate 5 to the exterior side 4 of the cutting tool 1 may (gradually) increase

[0107] FIG. 3 (as well as FIG. 2) further depicts the first layer element 20 comprising a plurality of first layer element layers 21. The first layer element layers 21 comprise different types of layers, of which two different types of layers 22, 23 are indicated. These different types of the layer 22, 23 differ in a silicon content and thus also in the content of at least one of the other metal elements Al, Cr, and Ti, which are especially all comprised in each of the first layer element layers 21. Hence a first type 22 of the layers 22, 23 has a highest silicon content C.sub.Si,H , and a second type 23 of the layers 22, 23 has a lowest silicon content C.sub.Si,L,

[0108] The ratio of the lowest silicon content C.sub.Si,L to the highest silicon content C.sub.Si,H may e.g., be about 0.5. For instance, C.sub.Si,H may be about 1.5 at % and C.sub.Si,L may be about 0.7 at %.

[0109] FIG. 3, further depicts the cutting tool 1 wherein the plurality of first layer element layers 21 comprise a number subs.sub.N of subsets 200 of the first layer element layers 21. A number of different first layer element layers 21 thus may define a subset 200 of first layer element layers 21 The depicted embodiment comprises six stacked subsets 200 (here subs.sub.N equals six), all comprising the first type 22 of the layers 22, 23 and the second type 23 of the layers 22, 23 plus a third (other) first layer element layer 21. Hence, at least two of the first layer element layers 21 in a subset 200 may comprise different silicon contents. In the depicted embodiment, a first first layer element layer 21, 23 (of the subset 200) may comprise a lowest silicon content, e.g. 0.7 at %; a second first layer element 21,22 (of the subset (200) may comprise a higher silicon content, e.g. 1.5 at %, and a third first layer element layer 21 may comprises an intermediate silicon content, e.g. 1 at %.

[0110] Also the subset thickness 205 is indicated. The subset thickness 205 of each of the subsets 200 may be equal to or smaller than 1.5 μm, especially equal to or smaller than 1 μm or equal to or smaller than 0.5 μm. Further, the thickness 215 of the first layer element layer 21 may in the given embodiment be in the range of equal to or smaller than 0.5 μm, especially equal to or smaller than 0.4 μm, such as equal to or smaller than 0.33 μm, such as equal to or smaller than 0.2 μm. In further embodiments, the thickness 205 of the subset 200 is in the range of 0.6-1.2 μm, especially in the range of 0.7-1 μm.

[0111] In embodiments, the configuration of the first layer element layers 21 in each of the subsets 200 may be identical. As such, the first layer element 20 may comprise a configuration with repeating first layer element layer 21 composition. If the embodiment in FIG. 3 would only comprise the lower three subsets 200, such a repeating configuration would have been provided. Yet, the configuration in one or more of the subsets 200 may also differ from the configuration of the other subsets 200 as is depicted with the subset 200′ on top of the lower three subsets 200. Other configurations are part of the invention as well. For instance, in yet further embodiments, the first layer element 20 comprises a number of subsets 200 configured between two (further) first layer element layers 21 (especially being different from the first layer element layers 21 in the subset 200).

[0112] The coating 10 of the invention may be produced by physical vapor deposition (PVD). During PVD the substrate 5 is rotated and especially during every rotation a very thin film or nanolayer 29 may be deposited. As such, every layer may comprise a plurality of stacked nano layers 29 as is also depicted in FIG. 3. For instance, the lowest first layer element layer 21; in the present embodiment a first type 22 of layer, comprises twelve of such nanolayers 29. The total of these nanolayers 29 may especially define the first layer element layer 21. The term “nanolayer” is known to the skilled person and especially refers to a layer in which the atoms provide a closed layer structure. A nanolayer may have a thickness 295 of only a few (metal) atoms, e.g. in the range of only a few nanometers up to e.g. several tens of nanometers. The nanolayer 29 may in embodiments have a thickness 295 in the range of 10-100 nm, especially 20-80 nm, such as 20-70 nm, especially 25-50 nm. Based on the rotation, the configuration of the cathodes 110 (see e.g. FIGS. 4-5) and especially the (variable) current applied, the composition of each nanolayer 29 may be heterogeneous, whereas the overall composition of each nanolayer 29 in the first layer element layer 21 is substantially the same (see below). A thickness 215 of the first layer element layer 21 may especially be hundreds of nanometers, e.g. in the range of 0.1-1 μm, especially in the range of 0.1-0.5 μm. In embodiments, the first layer element layer thickness 215 may be in the range of 100-500 nm, such as 250-400 nm.

[0113] FIG. 4, very schematically depicts a physical vapor deposition oven 100 with a vacuum chamber 150 comprising four metal cathodes 110. It is noted that each cathode 110 may be a single cathode 110. Yet, each cathode 110 may also represent a set or a plurality of the same cathodes 110. In the depicted embodiment, the number of cathodes Cat.sub.N is four. In the figure also a central axis 160 of the vacuum chamber 150 is depicted. Further, also the angle α between the cathodes 11 and 112 is depicted. Herein this angle α may also be described as the angle α between the cathodes (relative to the central axis 160).

[0114] For providing the first layer element 20, at least a subset of the Cat.sub.N cathodes 110, such as cathode 111, cathode 112, and cathode 113 together at least comprise Al, Cr, Ti, and Si. For providing other metal elements, at least one of the cathodes 110, e.g., cathode 114, may comprise the other elements

[0115] In FIG. 5 a further embodiment of a PVD oven 100 is depicted. In the embodiment, at each wall of the oven two cathodes 110 may be configured. This way two different cathodes 110, e.g. cathode 111 and cathode 112 may be arranged much closer to each other at an angle α being much smaller than 90°, e.g. at an angle α in the range of only a few degrees to less than 40 degrees, especially less than 25 degrees. Moreover, this way two cathodes 110, e.g. cathode 111 and cathode 112 may be arranged adjacent to each other, especially in one plane. The cathodes 111 and 112 are especially arranged at an inter-cathode distance dcc, which in this embodiment is smaller than the cathode dimension (or diameter) dc of cathode 112. Such configuration may in embodiments improve a distribution of silicon in the coating 10 being deposited if one of the cathodes indicated with reference 111 or 112 comprises the silicon.

[0116] It is noted that not all cathodes depicted in FIGS. 4-5 actually are present. The indicated cathodes 110 depict possible positions for a cathode 110. In further embodiments heating elements may be configured at one or more of the walls of the oven 100, and e.g. positions 113, 114, 117, and 118 are not present in the oven (because the respective walls comprise heating elements).

[0117] In the method, the substrate 5 is provided in the vacuum chamber 150 (wherein a vacuum is created) at temperatures in the range of 300-600° C. During depositing the substrate 5 is rotated as is indicated by the arrow. In the given embodiments around the central axis 160 of the chamber 150. Furthermore, for obtaining a nitride layer a nitrogen comprising gaseous fluid 120, such as nitrogen gas, is provided in the vacuum chamber 150. Optionally, especially during depositing the top layer element, also a carbon comprising gaseous fluid 130, e.g. methane, ethane, ethylene, or acetylene, is provided in the vacuum chamber 150 for providing a carbonitride layer. Further, metal and metalloid elements from the metal cathode 110 are evaporated by providing an electrical current to the cathode 110. The metal elements may react with the gaseous fluids 120, 130 and are attracted to the substrate by providing a (negative) bias voltage to the substrate 5 (over the substrate 5 and the vacuum chamber 150) and deposit on the substrate 5, thereby growing the coating 10, nanolayer 29 by nanolayer 29; layer by layer.

[0118] The composition of the coating 10 may thus among others be controlled by the composition of the cathodes 110. Yet, also the current to the cathodes 110, the positioning of the cathodes 110, the bias voltage, the temperature and the pressure in the chamber 150 may be configured for controlling the composition of the coating 10. By using four (sets) of cathodes 110, e.g. each single cathode 111, 112, 113, 114 could comprise just one or two (or more) of the respective metals Al, Cr, Ti, Si. Alternatively all the cathodes 110 may comprise a combination of the metals aluminum, chromium, titanium, and silicon. The different cathodes 110 may further have the metal elements in different ratios. Yet, in embodiments, one of the cathodes 110, e.g. cathode 114, may be configured for providing the base layer element 30 and/or the top layer element 40, and/or the intermediate layer element 50, optionally in combination with one or more of the other cathodes 111, 112, 113. In further embodiments, three cathodes 111, 112, 113, may be configured for providing the first element layer element 20. Hence, in embodiments three cathodes 110 together comprise the elements Al, Ti, Cr, and Si, especially in an amount that agrees with the composition of the coating 10, especially the first layer element 20 (of the invention) to be produced (taking into account that some metal elements may be deposited more preferred than other metal elements).

[0119] By using eight (sets) of cathodes 110, 111-118 (see FIG. 5) a degree of freedom is even further increased, In further embodiments, (at least) one of the cathodes 111, 112, 113, or e.g. of cathodes 111-118, may comprise an AlTiSi (or an AlCrSi) cathode (i.e. a cathode 110 substantially only containing the elements Al, Ti, (or Cr) and Si in a predetermined ratio) (herein also especially indicated as the first cathode) and one or two other ones of the cathodes 111, 112, 113 may comprise an AlCr (or ALTi) cathode (comprising substantially only Al and Cr (or Ti)) (herein also especially indicated as the second cathode(s)). In embodiments, the Si-containing cathode (such as AlCrSi) may be arranged between two AlTi cathodes. For instance cathodes 111 and 113 may be the second cathodes, such as AlTi cathodes, and cathode 112, arranged between the other two others 111, 113, may then be the first cathode, such as the AlCrSi cathode. The further cathode 114 arranged between the two other cathodes 111, 113 may e.g. comprise a Cr cathode. Yet other configurations are also feasible, wherein, e.g., cathodes 114 and 113 or 111 comprise second cathodes (and cathode 112 the first cathode). Further, with reference to FIG. 5, e.g. the first cathode may be arranged at position 112, and the second cathodes may be arranged at position 111 and e.g. position 114 or position 116. The first cathode may in further embodiments be arranged adjacent to one of the second cathodes and opposite to a further second cathode. For instance, a silicon containing cathode may be arranged at position 111 and the second electrodes (without silicon) may be arranged at positions 112 and 116. In embodiments, using AlCr (or AlTi) second cathodes 110 and an AlTiSi (or AlCrSi) first cathode 110 durable coatings 10 were produced when arranging a second cathode 110 adjacent to a first cathode 110 and opposite to a first cathode 110.

[0120] Having cathodes 110 comprising Al, Cr and/or Ti, but without containing Si, while having other cathodes 110 comprising Si allows for depositing the first layer element layers 21 comprising at least two different types of layers 22, 23, wherein the first type 22 has the highest silicon content C.sub.Si,H, and the second type 23 has the lowest silicon content C.sub.Si,L. This may e.g. be achieved by controlling the current (value(s) or duration) to change the amount of metal elements evaporated. By changing the current to the cathodes 110 also the amount of evaporated other metal and metalloid elements in the cathode 110 may change. This may in embodiments especially affect the titanium and/or chromium content in the coating 10. In embodiments, especially in each of the first layer element layers 21 a combination of titanium and chromium is available in the range of 21-27 at. %, such as in the range of 22-27 at. % relative to a total of the metal and the metalloid elements (in the respective) first layer element layer 21).

[0121] As discussed above, based on the composition and location of the cathodes 110 and because of the rotation of the substrate 5 during depositing a nanolayer 29 may be deposited every rotation. Such nanolayer 29 may therefore in embodiments comprise a heterogeneous composition. Hence, the first element layer 21 may comprise a repeating structure comprising a number of these nanolayers 29 stacked on top of each other, see FIG. 3. It is hypothesized that changing structures in the coating 10 facilitates the tool life. Moreover, it is hypothesized that also such substructure in the first layer element layer may positively affect the durability of the coated article 1.

[0122] The term “plurality” refers to two or more. Furthermore, the terms “a plurality of” and “a number of” may be used interchangeably. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. Moreover, the terms “about” and “approximately” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. For numerical values it is to be understood that the terms “substantially”, “essentially”, “about”, and “approximately” may also relate to the range of 90%-110%, such as 95%-105%, especially 99%-101% of the values(s) it refers to.

[0123] The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”.

[0124] The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

[0125] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0126] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0127] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0128] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0129] Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, “include”, “including”, “contain”, “containing” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0130] The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0131] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0132] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0133] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. Moreover, if a method or an embodiment of the method is described being executed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is suitable for or configured for (executing) the method or the embodiment of the method respectively.

[0134] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

EXPERIMENTAL

Tool Life for Cutting Tubes

[0135] Saw blades (both HSS saw blades as well as TCT saw blades) with different coatings have been tested. The coating composition was measured by SEM-EDX During the test, the saw blade was inspected at regular intervals of 1.2 m.sup.2 with an optical microscope with 500× magnification. The tests were stopped when a certain degree of damaged was observed.

[0136] TCT coated blades (350 mm diameter, kerf 2.7 mm, 120 teeth) were tested on a Rattunde AC S90 cutting machine, for cutting E355+N tubes with 50 mm diameter and 3 mm wall thickness. The cutting speed was 280 m/min, while the feed varied between 0.05 mm/tooth at the entrance and the exit of the tube, to 0.14 mm/tooth at the middle of the tube. So called micro spraying with emulsion was used for cooling and lubrication of the saw blade.

[0137] In the following table some relevant results on TCT coated blades are given:

TABLE-US-00002 Coating composition (excluding N and C) Experiment/ Al Cr Ti Si Functional layer Wear/damage sample no at. % at. % at. % at. % structure Thickness @ m.sup.2 Prior art 1 75 1 24 0 Multi 7 μm Heavy damage at 1.2 m.sup.2 Prior art 2 75 <0.2 25 0 Mono 4 μm Heavy damage at 1.2 m.sup.2 Prior art 3 80 19 0 1 Mono 6 μm Heavy damage at 1.2 m.sup.2 Prior art 4 71 29 0 0 Mono 6 μm Damage at 5 m.sup.2 Example 0 78 22 0 0 Mono 6 μm Damage at 1.2 m.sup.2 (V38) Example 1 73 18 8 1 2 layer 5 μm Damage at 2.4 m.sup.2 (V42) Example 1b 74 17 8 1 Mono 3 μm Damage at 1.2 m.sup.2 (V43) [like V42] Example 1c 73.5 15 9   2.5 Mono 2.5 μm Damage at 1.2 m.sup.2 (V44) Example 1d 74 19.5 5   1.5 Mono 3.5 μm Damage at 2.4 m.sup.2 (V45) Example 1e 74 19.5 5   1.5 Mono 2.5 μm Damage at 1.2 m.sup.2 (V46) [like V45] Example 2 74 16.5 8.5 1 Multi 4.5 μm Damage at 3.7 m.sup.2 (V47) [1;1.5] [CB] Example 3 74 17 8 1 Mono 4.5 μm Heavy damage at 5 m.sup.2 (V48) [like V43] Example 4 73.5 13.5 11.5   1.5 2 layer 5 μm Damage at 1.2 m.sup.2 (V49) ** Example 5 74 17 8 1 Multi 5 μm First wear signs at 5 m.sup.2; (V50) [0.7;1.5;1] [CBA] Can still be used after 7.4 m.sup.2 Example 6 74 18 7 0.9 Multi 5 μm Damage at 5 m.sup.2; Cannot be (V52) [l;0.7] [CA] used after 6.2 m.sup.2

[0138] In the table, the structure “mono” indicates that the saw blade has a coating comprising a single functional layer. The term “2 layers” indicates that the saw blade has two different functional layers (with Si). The term “multi” indicates that the first layer element comprises two or three different first layer element layers with different composition, the different compositions for the layers in the multilayers are indicated (with A, B, and C) between brackets under the term “multi” and the silicon amounts in the respective layers are indicated between brackets in the column “Coating composition; Si” (i.e. layer A comprising 1 at. % Si, layer B comprising 1.5 at % Si and layer C comprising 0.7 at % Si). Further, comparable coating compositions are also indicated in the column “structure”. The coatings further have a base layer, a top layer and optionally intermediate layers. In the experiments indicated as Example 1 to 1e, 2 to 3 and 5 to 6, four cathodes were used, wherein a first cathode consisted of aluminum and chromium (AlCr), a second one also consisted of aluminum and chromium (AlCr), a third cathode consisted of aluminum, titanium, and silicon (AlTiSi) and a fourth consisted of Cr (especially applied for the base layer element and/or the top layer element). In these experiments the second cathode and the third cathode were arranged next to each other and opposite to the first cathode (as well as the fourth cathode), i.e. referring to FIG. 5, for instance at positions 112, 111 and 116 (and 115) for respectively the second, third, and first (and fourth) cathode. As such, every composite layer is built layer-by-layer by a combination of cathodes 2 and 3 providing AlCrTiSiN and stacked by AlCrN provided by the oppositely arranged first cathode. For example 4 (experiment V49) also cathode 2 (AlCr) and cathode 3 (AlTiSi) were used. However, cathodes 2 and 3 were configured 180° from each other (opposite to each other) instead of adjacent to each other (and the Cr cathode was arranged next to cathode 2). Again referring to FIG. 5, for instance cathode 2 was arranged at position 112, and cathode 3 was arranged to position 116 (and the Cr cathode at position 111.

[0139] Based on these experiments the next conclusions are drawn: Prior art coatings 1-3 all show heavy damage at 1.2 m.sup.2, which is worse than all coatings of the invention

[0140] A saw blade with a coating resembling a coating as described herein, having two different first layer element layers with different compositions, but without silicon in the first layer element (Example 0) has a shorter tool life than the saw blades of the invention with the coatings described herein comprising 1 at. % silicon (Examples 1-3 and 5) and about the same tool life as Example 4, also comprising two first layer element layers with different composition, wherein the silicon content is about 1.5 at. %.

[0141] Further, it appears that if the silicon containing cathode is placed too far apart from the cathode without silicon as is done for Example 4, a less durable coating is obtained. It is assumed that in this experiment the structure that is needed, consisting of Al, Cr, Ti and Si forming one structure is not formed, but instead of this segregated structures of AlCrN and AlTiSiN are formed.

[0142] The position of the first AlCr cathode opposite to the combination of the second AlCr cathode and the AlTiSi cathode configured adjacent to each other (as used in the other experiments) leads to a confinement of AlCrTiSiN structure which consists of a Si.sub.3N.sub.4 center surrounded by AlCrTiN. When this structure grows too large, which would happen without the intermediate AlCr nano layers, an unstable structure appears to be formed which weakens the overall coating structure.

[0143] Further, all saw blades according to the invention seem to have a longer tool life than a prior art saw blade also comprising silicon, however not comprising titanium (prior art 3).

[0144] Especially multi layers seem to have a positive effect on the tool life during cutting of tubes (tube material). Example 5 seems to have the longest tool life. In example 5 the coating comprises about 15 first layer element layers comprising three different layer types.

[0145] It is to be expected that each individual layer varies in hardness, hot hardness, elastic modulus, tendency to chip welding and friction coefficient, as a direct consequence of the differences in Ti, Cr and Si concentration. It hypothesized that every individual layer can withstand the most dominant wear mechanism for each individual part of the tool: the most resistant layer survives the mechanism at play, the other layers quickly wear off. No single composition layer is capable to withstand the multiple modes of wear. Therefore, probably three different layers may provide a more durable coating than layers comprising two different compositions. The coating V50 has a structure where repeatedly three different layers are stacked, which seems to result in the longest tool life. For coatings having one or two of these three different layers, the coating seemed to fail earlier, and tool life is limited. This may especially be important when cutting a highly abrasive material intermittently, such as tubes, where several wear mechanisms are at play simultaneously at different parts of the tool.

Tool Life for Cutting Solids

[0146] For solid materials other mechanism may play a dominant rule. Using further experiments, it has been shown that for solid cutting, a single layer structure, as used in example 1b, 1c, and 3 showed good results and sometimes better than especially thicker multi-layered coatings.