JP2006009059A - Hard film, hard film-coated tool, and hard film coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a hard film containing W such as a TiWCN film to be coated on a base material of a tool such as a cemented carbide so as to have excellent adhesiveness. <P>SOLUTION: A hard film 14 of a single composition consisting of carbide (TiWC), nitride (TiWN) or carbo-nitride (TiWCN) of a TiW alloy is deposited on a surface of a base material 12 of a tool consisting of cemented carbide by an arc discharge ion plating method with the TiW alloy as a target. Thus, adhesiveness of cemented carbide consisting mainly of WC to the base material 12 of the tool is further enhanced by affinity for the TiW alloy with WC in comparison with a case that Ti compound and W compound are mixed in such a case that coating is performed while Ti and W are used for separate targets. Excellent wear resistance can be obtained thereby, and the practically satisfactory lifetime of the tool can be obtained even when chromium steel or the like is cut by dry working. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hard coating, and more particularly to a hard coating that provides excellent adhesion to a base material such as a cemented carbide containing WC.

For example, Patent Document 1 discloses the use of a TiWCN film as an abrasion-resistant hard film that is coated on the surface of a base material of a cemented carbide such as a cutting tool. Since the cemented carbide is composed mainly of WC (tungsten carbide), it has high affinity with a TiWCN film containing W (tungsten), and excellent adhesion is expected.
Japanese Patent No. 3249277

However, in Patent Document 1, the Ti target and the W target are each arc-discharged at a predetermined output voltage by an arc discharge ion plating method to evaporate them, and nitrogen gas (N ₂ ) and acetylene gas (C ₂ H _2). ), And a TiWCN film is coated on the base material of the cemented carbide. Therefore, the composition is microscopically mixed with TiCN and WCN, and the presence of TiCN does not necessarily provide the expected adhesion. There was a problem that it was not possible. That is, the arc discharge ion plating apparatus generally coats a member to be coated (tool base material) while rotating, while the two targets are arranged on opposite sides of the member to be coated, so that TiCN and WCN are It is in a state of being alternately stacked and mixed, and a hard film having a single composition called TiWCN is not provided.

  The present invention has been made in the background of the above circumstances, and its object is to coat a hard film containing W such as a TiWCN film with a more excellent adhesion to a base material such as a cemented carbide. There is to make it.

  In order to achieve such an object, the first invention is a hard film coated on the surface of a predetermined base material, and is composed of any one of a carbide, nitride, and carbonitride of a TiW alloy. It is characterized by being.

  A second invention is characterized in that the hard coating of the first invention is coated on the surface of the base material by an arc discharge ion plating method using a target of a TiW alloy.

  A third invention is characterized in that, in the hard coating of the first invention or the second invention, the base material is a cemented carbide containing WC.

According to a fourth invention, in any one of the hard coatings of the first to third inventions, (Ti _a W _b ) (C _x N _y ) [where a + b = 1 and 0 <a <1, x + y = 1 and 0 ≦ x ≦ 1].

  The fifth invention relates to a hard coating coated tool, characterized in that the hard coating of any one of the first to fourth inventions is coated on the surface of a cemented carbide tool base material containing WC. To do.

  A sixth invention is a method of coating a hard film on a surface of a predetermined base material, and uses a TiW-based alloy target in a predetermined gas atmosphere for making a carbide, nitride, or carbonitride. The film is formed by an arc discharge ion plating method, and the surface of the base material is coated with a hard film made of any one of carbide, nitride, and carbonitride of the TiW alloy.

  The seventh invention is characterized in that, in the hard film coating method of the sixth invention, the base material is a cemented carbide containing WC.

  Since such a hard coating is composed of any one of carbides, nitrides, and carbonitrides of TiW-based alloys, Ti compounds are used when coating using Ti and W as separate targets. Compared with the case where the W compound is mixed, the affinity between the TiW-based alloy and WC further improves the adhesion to a cemented carbide containing WC as a main component. The same effect can be obtained with respect to the fifth to seventh inventions related to the hard film-coated tool and the coating method.

  The present invention is preferably applied to a hard film coated on a cutting tool such as an end mill, a milling cutter, a drill, or a cutting tool, but can also be applied to a processing tool other than cutting such as a rolling tool. Of course, the present invention can be applied to a throw-away tip that is detachably attached to such a tool, and can also be applied to a case where a member other than a tool such as an electronic component is coated with a hard film.

  The hard coating of the present invention is desirably coated on a cemented carbide containing WC or the like, but can also be coated on a material not containing WC or a metal material other than cemented carbide. The hard film of the present invention is used as an intermediate layer, and another hard film such as a diamond film is further laminated thereon, the hard film of the present invention is laminated in multiple layers, or alternately with other hard films. Various modes in which the hard film of the present invention is coated so as to be in contact with at least the base material, such as lamination, are possible.

  The average film thickness of the hard coating of the present invention is appropriately determined depending on the use mode, such as whether it is used as an abrasion-resistant hard coating or an intermediate layer (underlying), but a tool for cutting cemented carbide. When the base material is coated with only the hard film of the present invention in a single layer, for example, a range of about 1 μm to 5 μm (particularly about 2 μm to 4 μm) is appropriate. When used as an intermediate layer, it may be thinner than this, for example, about 0.01 μm.

  As the TiW-based alloy, a TiW alloy composed mainly of Ti and W and the remainder consisting of inevitable impurities is preferably used, but other alloy elements such as Si can also be included. The atomic ratio between Ti and W in the TiW alloy, that is, a and b in the fourth invention are, for example, a = 0.75, b = 0.25, a = b = 0.5, a = 0.25 and b = 0. .75, etc. are appropriately determined.

The carbide, nitride, and carbonitride of the TiW alloy are those in which carbon or nitrogen is bonded to the TiW alloy, and specifically, TiWC, TiWN, and TiWCN. The atomic ratio of C and N in TiWCN, that is, x and y in the fourth invention is, for example, acetylene gas (C ₂ H ₂ ) or nitrogen gas (N ₂ ) introduced into the chamber (reactor) in the arc discharge ion plating method. ) Etc., and can be adjusted by changing the flow rate of the reaction gas.

  As the means for forming the hard coating of the present invention, an arc discharge ion plating method is preferably used, but other film forming techniques such as a PVD method can also be employed. In the arc discharge ion plating method, the bias voltage applied to the base material to be coated with the hard coating is appropriately determined according to the composition of the hard coating, the film forming conditions, and the like. When coating the TiWN film, for example, −30V A range of about -300V (particularly about -100V to -200V) is appropriate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are diagrams for explaining a throw-away tip 10 as a hard film-coated tool to which the present invention is applied, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view of a surface layer portion. The throw-away tip 10 is attached to a tool post of a lathe via a holder or the like and used for turning, etc., and has a substantially rhombus shape in a plan view, and a pair of parallel sides are cut. While being used as the blade 20, a mounting hole 22 through which a mounting bolt is inserted is provided in the central portion in plan view. Also, a pair of parallel sides are used as the cutting edge 20 on the opposite surface (the back surface in FIG. 1A) so that it can be used upside down.

The throw-away tip 10 is composed mainly of a tool base material 12 made of a cemented carbide whose main component is WC. On the surface of the tool base material 12, arc discharge ion plating using a TiW alloy as a target. A hard coating 14 of (Ti _a W _b ) (C _x N _y ) [where a + b = 1 and 0 <a <1, x + y = 1 and 0 ≦ x ≦ 1] is provided. That is, the hard coating 14 has a substantially uniform composition composed of TiWC in which carbon C is bonded to the TiW alloy, TiWN in which nitrogen N is bonded to the TiW alloy, or TiWCN in which carbon C and nitrogen N are bonded to the TiW alloy. It has been done. Moreover, the hard film 14 is a single layer, and the average film thickness is in the range of 1 μm to 5 μm.

FIG. 2 is a schematic configuration diagram (schematic diagram) illustrating an example of an arc discharge ion plating apparatus 50 that forms the hard coating 14 by the arc discharge ion plating method. A work holding tool 52, a rotating device 54 for rotating the work holding tool 52 around a substantially vertical rotation center, a bias power source 56 for applying a negative bias voltage to the tool base material 12, and the tool base material 12 inside. Chamber 58 serving as a processing furnace accommodated in the reactor, a reaction gas supply device 60 for supplying a predetermined reaction gas into the chamber 58, an exhaust device 62 for discharging the gas in the chamber 58 with a vacuum pump or the like, and reducing the pressure, an arc power source 64 etc. In this embodiment, the reactive gas supply device 60 supplies acetylene gas (C ₂ H ₂ ) or nitrogen gas (N ₂ ) to form carbide, nitride, or carbonitride. Further, the arc power source 64 uses a TiW alloy target 68 made of Ti and W as main components and the remainder of inevitable impurities as a cathode, and causes a predetermined arc current to flow between the anode 70 and arc discharge. The TiW alloy is evaporated from the target 68. In this embodiment, the atomic ratio of Ti and W of the TiW alloy constituting the target 68 is 0.75: 0.25. A plurality of targets 68 may be provided around the work holder 52 such as the opposite side (right side in FIG. 2) with the work holder 52 interposed therebetween, and the TiW alloy may be evaporated by arc discharge.

  Then, while supplying one or both of acetylene gas and nitrogen gas from the reaction gas supply device 60 so that the inside of the chamber 58 is maintained at a predetermined pressure while being exhausted by the exhaust device 62 in advance, a tool is supplied from the bias power source 56. When the TiW alloy is evaporated from the target 68 by the arc power source 64 while a predetermined bias voltage is applied to the base material 12 and the work holder 52 is rotated at a predetermined rotation speed by the rotating device 54, the evaporated TiW alloy is positive. It adheres to the surface of the tool base material 12 to which negative (−) bias voltage is applied as ions of (+) and combines with carbon C and nitrogen N of the acetylene gas and nitrogen gas to combine TiWC and TiWN. Alternatively, TiWCN is formed, and the hard coating 14 is formed. That is, if only acetylene gas is supplied as a reactive gas, a TiWC hard coating 14 is formed, if only nitrogen gas is supplied, TiWN hard coating 14 is formed, and if both acetylene gas and nitrogen gas are supplied, TiWCN A hard coating 14 is formed. The atomic ratio of C and N in TiWCN can be adjusted by changing the flow rates of acetylene gas and nitrogen gas.

  As described above, the throw-away tip 10 of the present embodiment is obtained by subjecting the TiW alloy carbide (TiWC) to the surface of the tool base 12 made of cemented carbide by arc discharge ion plating using the TiW alloy as the target 68. , Nitride (TiWN), or carbonitride (TiWCN), a hard coating 14 of a single composition is provided so that Ti and W can be coated as Ti and W as separate targets and Compared with the hard coating in which the W compound is mixed, the adhesion between the TiW alloy and WC makes it possible to further improve the adhesion of the WC-based cemented carbide to the tool base material 12. As a result, excellent wear resistance can be obtained, so that a practically satisfactory tool life can be obtained even when dry machining is performed on chromium steel having excellent wear resistance and oxidation resistance. Become.

  FIG. 3 shows the results of scratch tests performed by preparing nine types of samples No1 to No9. The “film composition” in the figure is the composition of the hard film coated on the surface of the tool base material, and the “film thickness” is the average film thickness of the hard film, and each of the tool base materials is mainly composed of WC. Cemented carbide (K10 type). Samples No. 5 to No. 9 whose “film composition” is TiWN, TiWCN, and TiWC are the same products of the present invention as in the above examples, and Samples No. 1 to No. 4 are comparative products. In addition, among the products of the present invention, samples No. 5 to No. 7 whose “film composition” is TiWN are different in bias voltage applied to the tool base material when the hard coating (TiWN) is coated by the arc discharge ion plating method. No5 is -30V, sample No6 is -150V, and sample No7 is -300V.

  The scratch test is for investigating the adhesion (adhesion strength) of the hard coating. While applying a continuously changing load (N) to the diamond cone, it is pressed against the specimen and scratched, and the hard coating is destroyed or peeled off. The acoustic emission (AE) generated when the detection signal is detected is detected, and the load when the detection signal suddenly rises is measured as the critical load. Therefore, the larger the critical load, the higher the adhesion strength, and the products of the present invention (Sample Nos. 5 to 9) all have higher adhesion strength than the comparative products (Samples No. 1 to No. 4). In particular, samples No. 5 to No. 7 whose “film composition” is TiWN have an adhesion strength of 40% or more higher than that of the comparative product.

4 to 6 show the cutting conditions of the samples No1 to No9 and the throwaway tip without coating (only the cemented carbide K10 base material) under the following processing conditions. This is a result of examining the relationship between the cutting length and the maximum flank wear width (VBmax).
(Processing conditions)
Work material: SCr420H (chromium steel)
Cutting speed: V = 5.0 m / s
Feeding speed: S = 0.2mm / rev
Cutting depth: a = 0.1 mm
Lubrication method: Dry Cutting method: Peripheral turning using NC lathe

  FIG. 4 is a comparison between the present invention product (sample No. 8) whose “film composition” is TiWCN and a comparative product (including no coating), and the maximum flank wear width (VBmax) is about 0.15 mm. Although the “film composition” is not so different from the comparative products of TiVN and TiAlN (sample No. 4 and No. 2), the product of the present invention does not progress so much even if VBmax exceeds 0.15 mm, and VBmax is generally regarded as the tool life. When the comparison is made at about 0.2 mm, it can be seen that the cutting length of the product of the present invention is about 1.5 times that of the comparative products (samples No. 4 and No. 2), and an excellent tool life (durability) can be obtained.

  FIG. 5 compares the products of the present invention (samples No. 6, No. 8, No. 9), and wear of TiWN (sample No. 6) is low from the beginning of processing. This is presumably because the hard coating becomes brittle due to carbon C. FIG. 6 compares the products of the present invention (sample Nos. 5 to 7) whose “film composition” is TiWN, and the most excellent durability is obtained when the bias voltage is −150 V (sample No. 6).

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the throw away tip which has a hard film of this invention, (a) is a perspective view, (b) is sectional drawing of a surface layer part. It is a schematic block diagram explaining an example of the arc discharge ion plating apparatus suitably used when coating the hard film of the throw away tip of FIG. It is a figure which shows the critical load of the sample prepared in order to clarify the effect of this invention, a film | membrane composition, a film thickness, and a scratch test. It is a figure which compares this invention product with a comparative product about the relationship between the cutting length at the time of cutting using the sample of FIG. 3, and the maximum flank wear width. It is a figure which compares and shows the relationship between the cutting length of this invention product, and the maximum flank wear width among the samples of FIG. It is a figure which compares and shows the relationship between cutting length and the maximum flank wear width about three types whose film composition is TiWN among the products of this invention of the sample of FIG.

Explanation of symbols

  10: Throw away tip (hard coating coated tool) 12: Tool base material 14: Hard coating 50: Arc discharge ion plating apparatus 68: Target

Claims (7)

A hard coating coated on the surface of a predetermined base material,
A hard coating film characterized by being composed of any one of a carbide, nitride, and carbonitride of a TiW alloy. The hard coating according to claim 1, wherein the surface of the base material is coated by an arc discharge ion plating method using a TiW-based alloy target. The hard coating according to claim 1, wherein the base material is a cemented carbide containing WC. (Ti _a W _b ) (C _x N _y ) [where a + b = 1 and 0 <a <1, x + y = 1 and 0 ≦ x ≦ 1] Hard coating of any one of Claims.   A hard film coated tool, wherein the hard film according to any one of claims 1 to 4 is coated on a surface of a cemented carbide tool base material containing WC. A method of coating a hard film on the surface of a predetermined base material,
Using a TiW-based alloy target, a film-forming process is performed by an arc discharge ion plating method in a predetermined gas atmosphere for forming a carbide, nitride, or carbonitride, and the TiW is applied to the surface of the base material. A method for coating a hard film, comprising: coating a hard film made of any one of a carbide, a nitride, and a carbonitride of an alloy. The method for coating a hard film according to claim 6, wherein the base material is a cemented carbide containing WC.

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