The present invention relates to a hard coating film and, more particularly, to improvement of a hard coating film having excellent wear resistance and adhesion resistance.
Attempts have heretofore been widely made with aims to form a hard coating film on a surface of a predetermined member such as a tool base member (tool base material) or the like which is made of high-speed tool steel and cemented carbide or the like. For instance, in Patent Publication 1, a proposal has been made to form a layer B with excellent adhesion resistance on a layer A having excellent wear resistance. The layer A is made of nitride and carbonitride, etc., of Ti, Cr, Al and Si or the like while the layer B is made of oxide and boronide, etc., of Ti, Cr, Al and Si or the like.
With the hard coating film of such a related art, the tool base material or the like could not necessarily have adequate bonding strength. That is, for instance, an issue has been arisen with the occurrence of peel-off or wear due to chipping on early stages with resultant consequence of a deteriorated work surface and a variation in cutting performance when cutting work is performed on stainless steel or when cutting work is performed on a workpiece material which has increased likelihood of adhesion and whose hardness is 50 HRC or less.
The present invention has been completed with the above view in mind and has an object to allow a hard coating film, having excellent wear resistance and adhesion resistance, to be formed on a tool base material with increased bonding strength for stably obtaining excellent wear resistance and adhesion resistance over a long period of time.
To achieve the above object, the first aspect of the present invention provides a hard coating film formed on a surface of a predetermined member and having excellent wear resistance and adhesion resistance, the hard coating film comprising: (a) a three-layer structure composed of a third layer formed in contact with the surface of the predetermined member, a second layer formed on the third layer, and a first layer formed on the second layer to constitute the surface; (b) the first layer being made of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d) [provided that SiC is silicon carbide, and a, b, c and d are atomic ratios in ranges of 0≦a≦0.2, 0.01≦b≦0.2, 0≦c≦0.5 and 0≦d≦0.3, respectively; (c) the second layer being made of AlCrN or AlCrDN [provided that D includes either one kind of elements of a Group IVa, a Group Va and a Group VIa (except Cr) of a Periodic Table of Elements and Y, or SiC (silicon carbide)]; and (d) the third layer being made of nitride, carbon nitride or carbide of metals including elements of one kind or more kinds of Al, Ti, Zr, Hf, V, Nb, Ta, Cr and W.
The second aspect of the invention provides the hard coating film recited in the first aspect of the invention, wherein (a) a mixed layer of the first and second layers having both compositions of the first and second layers is formed in a boundary portion between both layers by switching forming treatments of the first and second layers at shifted timings such that the forming treatments are in duplication for a predetermined time interval; and (b) a mixed layer of the second and third layers having both compositions of the second and third layers is formed in a boundary portion between both layers by switching forming treatments of the second and third layers at shifted timings such that the forming treatments are in duplication for a predetermined time interval.
The third aspect of the invention provides the hard coating film recited in the first or second aspect of the invention, wherein (a) a total film thickness Ttotal of the first layer, the second layer and the third layer lies in a range of 0.05 to 15 μm; (b) a film thickness T1 of the first layer lies in a range of 1 to 50% of the total film thickness Ttotal; (c) a film thickness T3 of the third layer lies in a range of 1 to 25% of the total film thickness Ttotal; and (d) a film thickness T2 of the second layer lies in a value of (Ttotal−T1−T3).
The fourth aspect of the invention relates to a hard coating film coated working tool including a tool base material of which surface is coated with the hard coating film in any of the first to third aspects of the invention.
With a hard coating film of a first aspect of the present invention, a second layer is made of AlCrN or AlCrDN [provided that D includes either one kind of elements of a Group IVa, a Group Va and a Group VIa (except Cr) of a Periodic Table for Elements and Y, or SiC (silicon carbide)], by which excellent wear resistance is obtained. A first layer is provided at the uppermost layer and made of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d) [provided that SiC is silicon carbide, and a, b, c and d are atomic ratios in ranges of 0≦a≦0.2, 0.01≦b≦0.2, 0≦c≦0.5 and 0≦d≦0.3, respectively], by which excellent adhesion resistance is obtained. A third layer, intervened between a predetermined member, such as a tool base material or the like on which the hard coating film is to be formed, and the second layer, is made of nitride, carbon nitride or carbide of metals including elements of one kind or more kinds of Al, Ti, Zr, Hf, V, Nb, Ta, Cr and W, by which increased bonding strength is obtained. This allows excellent wear resistance and adhesion resistance to be stably obtained over an extended period of time. In case of, for instance, a hard coating film coated machining tool as defined by a fourth aspect of the present invention, the occurrence of peel-off and wear due to chipping can be suppressed and a favorable work surface is obtained even when performing cutting work on stainless steel or when performing cutting work on a workpiece material which has likelihood of adhesion and whose hardness is 50HRC or less. Further, this results in a capability of obtaining predetermined cutting performance with a resultant increase in tool life. In particular, since the first layer, formed at the uppermost layer, includes SiC (silicon carbide), a surface hardness increases (to a level of, for instance, 3000 HV or more), then due to the increased surface hardness as well as adhesion resistance and bonding strength a remarkable increase in wear resistance is obtained. This provides an excellent wear-resistance increasing effect especially when cutting work is performed on the workpiece material with high hardness.
According to a second aspect of the present invention, a mixed layer of both of the first and second layers is formed in a boundary portion between such layers and a mixed layer of both of the second and third layers is formed in a boundary portion between such layers. This result in an increase in mutual bonding strength among the first, second and third layers with a resultant further enhanced effect of suppressing the occurrence of peel-off and wear due to chipping. When the first to third layers are formed by a PVD method such as an arc ion plating method and a sputtering method or the like, forming the first to third layers including such mixed layers can be formed continuously and efficiently by appropriately determining timing for targets and/or reaction gases to be switched such that the mixed layers are formed.
According to a third aspect of the present invention, a total film thickness Ttotal of the first to third layers lies in a range of 0.05 to 15 μm, in which: a film thickness T1 of the first layer lies in a range of 1 to 50% of the total film thickness Ttotal; a film thickness T3 of the third layer lies in a range of 1 to 25% of the total film thickness Ttotal; and a film thickness T2 of the second layer lies in a value of (Ttotal−T1−T3). This allows various effects to be obtained including improvement in adhesion resistance by the first layer, improvement in wear resistance by the second layer and improvement in bonding strength by the third layer.
a) to 1(c) are views illustrating an end mill, to which the present invention is applied, and
10: end mill (hard coating film coated working tool) 12: tool base material (predetermined member) 20: hard coating film 22: first layer 24: second layer 26: third layer
The present invention can be preferably applied to a hard coating film, formed on surfaces of various working tools such as rotary cutting tools like an end mill, a tap and a drill, etc., and, in addition, a non-rotary type cutting tool such as a turning tool or the like or a rolling tool or the like. The present invention can also be applied to a hard coating film which is formed on a surface of a member aside from the cutting tools, for example, a surface protective film of a semiconductor device or the like. Means for forming the hard coating film may preferably include a PVD (Physical Vapor Deposition) method such as an arc ion plating method, a sputtering method, or the like.
According to the second aspect of the present invention, although the mixed layer of the first and second layers is formed in the boundary portion between both layers and the mixed layer of the second and third layers is formed in the boundary portion between both layers, no mixed layers can be provided. The first layer may be directly formed on the second layer and the second layer may be directly formed on the third layer. The mixed layer may be provided only in either one of the boundary portion between the first and second layers and the boundary portion between the second and third layers.
According to the third aspect of the present invention, the total film thickness Ttotal lies in the range of 0.05 to 15 μm. If the total thickness Ttotal is less than 0.05 μm, then, it becomes difficult to obtain the hard coating film with adequate performance and if the total thickness Ttotal exceeds 15 μm, then, a cutting chip of the cutting tool is rounded or the like with resultant likelihood of deterioration caused in tool performance. The film thickness T1 of the first layer lies in the range of 1 to 50% of the total film thickness Ttotal. If the film thickness T1 is less than 1%, then, an adhesion-resistance improving effect of the first layer can not be adequately obtained and if the film thickness T1 exceeds 50%, then, it is likely that deterioration occurs in improvement of wear resistance of the second layer. In addition, the film thickness T3 of the third layer lies in the range of 1 to 25% of the total film thickness Ttotal. If the film thickness T3 is less than 1%, then, a bonding-strength improving effect of the third layer can not be adequately obtained and if the film thickness T3 exceeds 25%, then, it is likely that deterioration occurs in a wear-resistance improving effect of the second layer.
Examples of a tool base material for the hard coating film coated working tool may preferably include cemented carbide, high-speed tool steel, cermet, ceramics, polycrystalline diamond (PCD), monocrystalline diamond, polycrystalline CBN and monocrystalline CBN or the like but other tool base materials may be possible to be adopted.
Hereunder, an embodiment of the present invention will be described below in detail with reference to the accompanying drawings.
a) to 1(c) are views illustrating a ball end mill 10 representing one example of a hard coating film coated working tool, to which the present invention is applied, and
As will be clear from
The second layer 24, provided on the third layer 26, is made of AlCrN or AlCrDN [provided that D includes either one kind of elements of a Group IVa, a Group Va and a Group VIa (except Cr) of a Periodic Table of Elements and Y, or SiC (silicon carbide)]. As exemplarily shown in a column, for instance, “SECOND LAYER” of “COATING FILM STRUCTURE” in
The first layer 22, i.e., the uppermost layer being formed on the second layer 24 and forming the surface of the hard coating film 20, is made of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d) [provided that SiC is silicon carbide, and a, b, c and d represent atomic ratios in ranges of 0≦a≦0.2, 0.01≦b≦0.2, 0≦c≦0.5 and 0≦d≦0.3, respectively]. As exemplarily shown in a column, for instance, “FIRST LAYER” of “COATING FILM STRUCTURE” in
Further, a total film thickness Ttotal of a whole of the hard coating film 20, formed of the first layer 22, the second layer 24 and the third layer 26 in combination, lies in a range of 0.05 to 15 μm. A film thickness T1 of the first layer 22 lies in a range of 1 to 50% of the total film thickness Ttotal; a film thickness T3 of the third layer 26 lies in a range of 1 to 25% of the total film thickness Ttotal; and a film thickness T2 of the second layer 24 lies in a value of (Ttotal−T1−T3). Each value with the mark “%”, described in parentheses in columns on the film thickness in
With a hard coating film 20 of a ball end mill 10 in the embodiment as such, a second layer 24 is made of AlCrN or ALCrDN by which excellent wear resistance is obtained. A first layer 22 is provided at the uppermost layer and made of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d) by which excellent adhesion resistance is obtained. A third layer 26, intervened between a tool base material 12 and the second layer 24, is made of nitride, carbon nitride or carbide of metals including elements of one kind or more kinds of Al, Ti, Zr, Hf, V, Nb, Ta, Cr and W by which increased bonding strength is obtained. This allows excellent wear resistance and adhesion resistance to be stably obtained over an extended period of time. The occurrence of peel-off and wear due to chipping can be suppressed even when performing cutting work on stainless steel or when performing cutting work on a workpiece material with likelihood of adhesion caused under hardness of 50 HRC or less. This results in a capability of obtaining a favorable work surface while making it possible to stably obtain predetermined cutting performance with a resultant increase in tool life.
In particular, since the first layer 22, formed at the uppermost layer, includes SiC (silicon carbide), a surface hardness increases to a level (of, for instance, 3000 HV or more) with resultant improvements in wear resistance and bonding strength accompanied by a remarkable increase in wear resistance. This provides an excellent wear-resistance increasing effect especially when cutting work is performed on the workpiece material with increased hardness.
According to the embodiment, a boundary portion between the first and second layers 22, 24 is formed in a mixed layer of both of such layers and a boundary portion between the second and third layers 24, 26 is formed in a mixed layer of both of such layers. This result in an increase in mutual bonding strength among the first, second and third layers 22, 24 and 26 with a resultant further enhanced effect of suppressing the occurrence of peel-off and wear due to chipping. In the embodiment, so that the first to third layers 22-26 are formed by an arc ion plating method, further, appropriately determining timing for targets and reaction gases to be switched such that the mixed layers are formed results in a capability of continuously and efficiently forming the first to third layers 26-22 including such mixed layers.
According to the embodiment, a total film thickness Ttotal of the first to third layers 22-26 lies in a range of 0.05 to 15 μm in which: a film thickness T1 of the first layer 22 lies in a range of 1 to 50% of the total film thickness Ttotal; a film thickness T3 of the third layer 26 lies in a range of 1 to 25% of the total film thickness Ttotal; and a film thickness T2 of the second layer 24 lies in a value of (Ttotal−T1−T3). This allows various effects to be appropriately obtained including improvement in adhesion resistance of the first layer 22, improvement in wear resistance of the second layer 24 and improvement in bonding strength of the third layer 26.
Next, two-blade type ball end mills 10 (corresponding to present invention products that satisfy requirements of claims 1 to 3) of the present embodiment, including the tool base materials 12 made of cemented carbide and having a diameter of 6 mm (with a tip radius R=3), and comparative products unsatisfying the requirements of claim 1 or 3, in existences, components, atomic ratios, and thicknesses of the first layer 22, the second layer 24 and the third layer 26 which form the hard coating films 20 were prepared. Then, cutting works were conducted under test conditions described below, to perform cutting works in length of 210 m and resulting relief-surface (flank-surface) wearing widths (mm) of the ball blades 18 were checked and described below. All items in
(Test Condition)
The present invention products, shown in
These test pieces have columnar shapes each with a diameter of 6 mm and each apex rapping surface being formed in a spherical surface of R5. Further, two pieces of test pieces, each of them having a rapping surface coated with the hard coating film 20 of the present invention and two pieces of test pieces, each of them having a rapping surface coated with hard coating film of a single layer composed of only AlCrN of the related art are prepared respectively. Then, friction wear tests were conducted by using a pin-on-disk type test machine shown in
(Test Condition)
Although the embodiments of the invention have been described in detail with reference to the drawings, the embodiments are merely examples, and the invention can be implemented in various forms obtained by altering or modifying the embodiments based on the knowledge of those skilled in the art.
With a hard coating film of the present invention, a second layer is made of AlCrN or AlCrDN by which excellent wear resistance is obtained. A first layer is provided at the uppermost layer and made of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d) by which excellent adhesion resistance is obtained. A third layer, intervened between a tool base material and the second layer, is made of nitride, carbon nitride or carbide of metals including elements of one kind or more kinds of Al, Ti, Zr, Hf, V, Nb, Ta, Cr and W by which increased bonding strength is obtained. This allows excellent wear resistance and adhesion resistance to be stably obtained over an extended period of time. The occurrence of peel-off and wear due to chipping can be suppressed even when performing cutting work on stainless steel or when performing cutting work on a workpiece material with likelihood of adhesion. This results in such as a capability of obtaining a favorable work surface while making it possible to stably obtain predetermined cutting performance. It is preferably adopted as the hard coating film of the cutting tools or the like for cutting work.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2008/062725 | 7/14/2008 | WO | 00 | 1/13/2011 |
Publishing Document | Publishing Date | Country | Kind |
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WO2010/007661 | 1/21/2010 | WO | A |
Number | Name | Date | Kind |
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20060269789 | Toihara et al. | Nov 2006 | A1 |
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1872536 | Dec 2006 | CN |
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A-2004-269985 | Sep 2004 | JP |
A-2007-002304 | Jan 2007 | JP |
A-2007-015106 | Jan 2007 | JP |
WO2006084404 | Aug 2006 | WO |
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Number | Date | Country | |
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20110117342 A1 | May 2011 | US |