JP2007136611A - Amorphous carbon coated cutting tool and manufacturing method for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amorphous carbon coated cutting tool, having an effect of restraining the development of cracks while having high hardness and moderate tenacity, having a low coefficient of friction and effective in adhesion resistance and a manufacturing method for an amorphous carbon film. <P>SOLUTION: The amorphous carbon coated cutting tool and manufacturing method thereof are characterized in that in this amorphous carbon coated cutting tool coated with the amorphous carbon film, the amorphous carbon film contains at least one or more kinds of elements among B, Cl, S, P, F, O and N, and the content of the element ranges from 0.01 to 25%, both inclusive, by atomic%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to drills for drilling, reamers, side milling end mills, routers, inserts for cutting tools with exchangeable cutting edges, used for processing non-ferrous materials, soft metal materials, organic materials, hard particle-containing materials, etc., or printed circuit boards. The present invention relates to a tool coated with an amorphous carbon film and a method for producing the same.

  Patent Documents 1 to 7 disclose amorphous carbon films.

JP 2003-62706 A JP 2005-256095 A JP 2000-144428 A JP-A-3-33641 JP-A-5-42398 JP-A-7-98278 JP 2005-500440 gazette

Patent Document 1 discloses an amorphous carbon-coated tool in which a tool cutting edge made of a WC-based cemented carbide has an amorphous carbon film. This WC-based cemented carbide has a Co content of 12% by mass or less. Patent Document 2 discloses a technique in which an element selected from S, F, Cl, and B is contained in a hard film containing carbon. Patent Document 3 discloses a gettering effect of hydrogen ions and the like by adding a halogen element and a P element to a DLC thin film. Patent Document 4 discloses a role for stabilizing the structure of carbon particles by adding F atoms to the carbon film. It also discloses the application of a carbon film to the cutting edge of a cutting tool. Patent Document 5 discloses an effect of increasing the crystal growth rate by using a raw material containing an F element in a vapor phase synthesis method of crystalline carbon. Patent Document 6 discloses a technique in which a diamond-like carbon thin film contains one or more of N, P, O, and F elements. Patent Document 7 discloses a layer containing O and N elements in a layer having a matrix phase of amorphous carbon or DLC and a nanoscale intervening phase.
However, since the above technique is a film intended to increase the hardness, no mention is made of measures for mechanical strength and progress of cracks. Therefore, the present invention provides an amorphous carbon-coated cutting tool effective in suppressing crack growth, a low friction coefficient, and adhesion resistance while having high hardness and appropriate toughness, and a method for producing the same. is there.

  The present invention relates to an amorphous carbon coated cutting tool coated with an amorphous carbon film, wherein the amorphous carbon film contains at least one element of B, Cl, S, P, F, O, and N And, the content of the element is an amorphous carbon-coated cutting tool characterized in that it is 0.01% or more and 25% or less in atomic%. Amorphous carbon coated cutting tool adopting the above configuration has the effect of suppressing crack growth while having high hardness and moderate toughness, and is effective for low friction coefficient and adhesion resistance, and stable performance. An amorphous carbon-coated cutting tool can be provided.

  The method for producing the amorphous carbon film of the present invention is a filter type arc ion plating (hereinafter referred to as FAIP) method, or a method in which the FAIP method and plasma chemical vapor deposition (hereinafter referred to as PCVD) method are combined. It is preferable to coat with. When coating by the FAIP method, ions emitted from the solid target mounted on the FAIP evaporation source are deflected by a magnetic field, and the deflection angle α (degree) is 30 ≦ α <90. A production method is preferred. It is preferable to add at least one of B, Cl, S, P, F, O, and N to the amorphous carbon film by the PCVD method.

  The present invention relates to an amorphous carbon-coated cutting tool effective in suppressing crack propagation, low friction coefficient, and adhesion resistance while having high hardness and appropriate toughness, and method for producing an amorphous carbon film Could be provided. For example, it is most suitable for cutting of materials containing hard particles such as non-ferrous metals such as aluminum, titanium, magnesium and copper, organic materials, and graphite, which are likely to cause adhesion. The tool of the present invention enables high-life and high-efficiency machining, and can maintain the finished surface shape and dimensional accuracy of the work material with high quality. Since the cutting resistance is extremely low, even if no cutting fluid is used, the life and cutting efficiency are high, which is extremely effective for improving productivity and reducing costs. Furthermore, it can meet the needs of environmental conservation and energy saving.

When processing materials containing hard particles such as non-ferrous metals such as aluminum, titanium, magnesium and copper, organic materials, and graphite as work materials, the finished surface shape and dimensional accuracy are maintained with high quality. That is required for cutting tools. However, there is a problem that the work material adheres to the cutting edge portion of the cutting tool, the cutting resistance increases, and the cutting edge is lost. This is because the adhesion of the tool surface is more likely to occur than other work materials, and the chipping of the cutting edge due to the adhesion and the reduction of machining accuracy are remarkable. Therefore, an important point in achieving the present invention is to add at least one of B, Cl, S, P, F, O, and N to the amorphous carbon film. When these elements are added, the amorphous carbon film has high hardness and moderate toughness, and has an effect of suppressing crack propagation, a low coefficient of friction, and adhesion resistance. Amorphous carbon films can greatly improve lubrication properties and adhesion resistance. Said additive element is limited to 0.01 atomic% or more and 25 atomic% or less. When the content of the additive element is less than 0.01 atomic%, the effect of suppressing crack propagation is not sufficiently exhibited while having high hardness and appropriate toughness. On the other hand, if it exceeds 25 atomic%, the effect of improving the lubricity is recognized, but the film hardness is remarkably lowered and the wear resistance is not exhibited. For these reasons, the present invention limits the content of additive elements to 0.01 atomic% or more and 25 atomic% or less. In particular, the B, S, F, O, and N elements can effectively contain toughness because they can contain a relatively soft material in a high hardness amorphous carbon film. This is effective for suppressing crack propagation. Furthermore, the content of these additive elements is more preferably 0.3 atomic% or more and 5 atomic% or less. For example, the presence of the h-BN phase has an effect of improving lubrication characteristics and adhesion resistance together with a crack progress suppressing effect. On the other hand, the elements B, F, and N become hard materials by controlling the plasma energy amount, which is a setting condition at the time of film formation, imparting appropriate toughness to a higher hardness amorphous carbon film, and have a balanced hardness. Can be a material. For example, the presence of a c-BN phase is preferable. In order to effectively exhibit these effects, it is more preferable that the content of the additive element is 5 atomic% or more and 15 atomic% or less. Furthermore, by adding Cl and F halogen elements to the amorphous carbon film, the thermal conductivity is improved, which contributes to the improvement of heat resistance. In order to fully exhibit this effect, it is preferable to make it content of 10 atomic% or more and 25 atomic% or less.
Here, when a nonmetallic element is added to the amorphous carbon film, a gas obtained by diluting various reaction gas species with an inert gas such as Ar or He can be used. Examples of reactive gas species include halogenated hydrocarbon gases such as B ₂ H ₆ gas, NH ₄ Cl gas, H ₂ S gas, PH ₃ gas, SiF ₄ gas, CF ₄ gas, NF ₃ gas, and CH ₃ F, O _Two gases, ammonia gas, amine compound, N ₂ gas, H ₂ gas, hydrocarbon gas, and the like can be used in appropriate combination. Separately, as a means for adding these non-metallic components, it is possible to add them to the target in advance by the FAIP method. For example, it is possible to add MoS2 or WS2 to the target and add S element.

The amorphous carbon film of the present invention preferably has a hydrogen content of at least 5% in atomic percent and not more than 15%. If it is in this range, the friction coefficient of the amorphous carbon film is lowered, the brittleness of the film is suppressed, and the toughness which is a chipping resistance property is preferably improved. On the other hand, when the hydrogen content is 5% or less, cracking and adhesion of the film, which are the dominant factors of chipping, are likely to occur, and the tool life becomes unstable. On the other hand, if it exceeds 15%, the graphitization of the amorphous carbon film tends to proceed during the cutting process, and as a result, the wear resistance tends to deteriorate, which is inconvenient. The amorphous carbon film of the present invention has a hardness of 20 GPa or more according to an indentation hardness measurement method to which a measurement load of 0.5 mN or more and 50 mN or less is applied. Therefore, it differs from a low hardness amorphous carbon film having a hydrogen content of 20% or more used for machine parts and the like.
Aside from this, the amorphous carbon film of the present invention has a laminated structure with a coating layer containing at least one of Ti, Cr, Al, Si, and V, and has a laminated structure of 2 layers or more and 900 layers or less. In the case of being composed of a film, it is particularly preferable because it is effective in suppressing brittleness of the film, improving toughness as a chipping resistance property, and improving wear resistance. On the other hand, in the case of 900 layers or more, the film thickness of the amorphous carbon film is substantially increased, and it has been confirmed that the film peeling is induced. When the lamination period is 0.5 nm or more and less than 30 nm, the balance between the film hardness and the toughness is optimal. Further, when the amorphous carbon film is the outermost layer and the underlayer at the interface between the substrate and the amorphous carbon film is a nitride or carbonitride selected from Ti, Cr, Al, Si, the present invention The characteristics of the amorphous carbon film can be improved. It is particularly suitable when the workpiece contains an iron-based compound or when hard particles are dispersed and contained, and exhibits the effects of the present invention.
When the diameter of the cutting tool covering the amorphous carbon of the present invention is 0.02 mm or more and less than 1.2 mm, the effect of the present invention is easily obtained, which is preferable. This is because the lubricating properties of the film are particularly required on the smaller diameter side than 1.2 mm. On the other hand, when the thickness is 1.2 mm or more, the effect of the present invention is not sufficiently exhibited, and it is difficult to manufacture a tool of less than 0.02 mm.
The substrate of the amorphous carbon-coated cutting tool of the present invention is preferably one of cemented carbide, cermet, and high-speed steel having a Co content of 3 wt% or more and less than 12 wt%. Any material can exhibit excellent adhesion strength and abrasion resistance between the substrate and the film. When the Co content in the cemented carbide is less than 3% by weight, it is inconvenient because it is inferior in chipping resistance of the tool edge. If it is 12% by weight or more, the deformation of the amorphous carbon film cannot follow the deformation of the substrate. For this reason, the adhesion strength of the film is remarkably lowered, which is inconvenient. The cemented carbide has a WC average particle size of 0.2 μm or more and less than 0.8 μm, and contains at least one carbide or carbonitride selected from Ta, V, Cr, Co, and W. In this case, it is particularly preferable from the viewpoints of adhesion strength with the coating of the present invention, coating strength, and wear resistance. On the other hand, when the WC average particle size is less than 0.2 μm, chipping occurs, which is inconvenient. On the other hand, when the thickness is 0.8 μm or more, in the ion cleaning performed as the surface treatment before coating, the surface unevenness becomes large and the adhesion is deteriorated.
When the amorphous carbon-coated cutting tool of the present invention is a printed circuit board processing tool, it is preferable because it can satisfy both the adhesion resistance and wear resistance characteristics.

  The method for producing an amorphous carbon film of the present invention is optimally coated by the FAIP method or a method combining the FAIP method and the PCVD method. The FAIP method has a high hardness and can coat a film excellent in surface smoothness. Moreover, by using together with PCVD, the gas component element can be easily added to the amorphous carbon film. The ions emitted from the solid target mounted on the evaporation source of the FAIP method are deflected by the magnetic field and fly toward the substrate surface along the magnetic field lines. It is preferable that α reaches the surface of the substrate in the range of 30 ≦ α <90 and film formation is performed. Here, the angle α is an angle formed by a straight line perpendicular to the target surface and a tangent to the trajectory drawn by ions emitted from the target surface. When α is less than 30 degrees, the coating is not sufficiently hard. On the other hand, when the angle is 90 degrees or more, the film formation rate is extremely low, and a uniform film is not formed on the coated substrate. Further, it is preferable to add at least one of B, Cl, S, P, F, O, and N to the amorphous carbon film by PCVD. At this time, a means for ionizing the gas component can be achieved by separately providing a holo cathode electrode in the film forming apparatus. By adding an ionized gas component to the amorphous carbon film, it has an effect of suppressing crack propagation, a low friction coefficient, and an anti-adhesion property while having high hardness and appropriate toughness. In particular, it is possible to form a film having low frictional resistance and excellent adhesion resistance. On the other hand, when a plasma source by sputtering is used as a means for ionizing the nonmetallic component, ionization of the nonmetallic component is insufficient because the plasma density is relatively low. Also, the activity of the ionized non-metallic component is low. Therefore, it is difficult to embed a compound containing a nonmetallic component as a nano-order dispersed phase in the matrix phase of the amorphous carbon film. In that respect, it is preferable to coat by the FAIP method capable of realizing ionization having high activity or a method combining the FAIP method and the PCVD method. Next, the amorphous carbon-coated cutting tool of the present invention will be specifically described with reference to examples.

  FIG. 1 is a small-diameter drill made of cemented carbide used as a base material, having a tool diameter of 0.1 mm and a groove length of 1.5 mm. The WC average crystal grain size of Invention Example 1 shown in Table 1 is 0.6 μm, the Co content is 8 wt%, and Cr and TaC are contained in addition to WC—Co. The hardness was HRA93.7. Table 1 shows the tool bases used in Invention Examples 1 to 26 and Comparative Examples 27 to 32.

The tool base was degreased and cleaned, and mounted on a film forming apparatus having a FAIP evaporation source and a holo cathode electrode provided at the center of the film forming apparatus. A graphite target having a purity of 99.99% cooled with water through a thin copper plate is fixed to the FAIP evaporation source. Permanent magnets or electromagnets are disposed so as to surround the outer periphery of the graphite target, and the arc spot has a function capable of moving efficiently. With this function, the graphite target was ionized. Ions emitted from the graphite target are deflected and reach the substrate. The deflection angle α at this time is also shown in Table 1.
As the film forming conditions, the substrate was heated to 200 ° C. by a heating source installed in the film forming apparatus container. At the same time, evacuation was performed and the pressure in the container was set to 5 × 10 ⁻⁴ Pa. Thereafter, the substrate was set at 80 ° C., and Ar and H ₂ were introduced into the container. The gas was ionized with the electrode provided in the container, and the tool surface was cleaned. The bias voltage value at this time was −150 V for 10 minutes. Next, Ar was introduced into the container, and the pressure in the container was set to 5 × 10 −1 Pa. As needed, the bombardment process and / or the coating of the underlayer were performed with a metal target installed in another FAIP evaporation source. The supply current value at this time was 60 A, and the bias voltage value was −500 V for 2 minutes. The coated underlayer is also shown in Table 1. Next, a current of 60 A was supplied to the FAIP evaporation source equipped with the graphite target to coat the amorphous carbon film. Simultaneously with the coating of the amorphous carbon film, at least one of nonmetallic elements B, Cl, S, P, F, O, and N was added by the PCVD method. In the addition method, a gas containing the additive element was introduced from the vicinity of the holocathode electrode installed in the center of the container, and a current was supplied to the electrode to ionize the gas component. The ionized gas component was added to the amorphous carbon film by a bias voltage. The additive elements and film thickness are shown in Table 1.

  For quantification of the hydrogen content in the amorphous carbon film of the present invention, RBS (Rutherford Backscattering Spectrometry) analysis and ERDA (Elastic Recoil Detection Analysis) analysis were used. The measurement conditions at this time were a beam energy of 2.3 MeV, an ion species of He ion, a scattering angle of 170 degrees and 30 degrees, a sample current of 30 nA, and a beam irradiation amount of 40 μC. For qualitative and quantitative analysis of the non-metallic component of the amorphous carbon film, X-ray photoelectron spectroscopy (hereinafter referred to as XPS), electron beam energy loss analysis (hereinafter referred to as EELS), Auger electron spectroscopy. Analysis (hereinafter referred to as AES) and the like. Examples of qualitative analysis of metal components include AES, energy dispersive X-ray analysis (hereinafter referred to as EDS), and the like. The analysis results are also shown in Table 1.

About each tool shown in Table 1, drilling process evaluation was performed on condition of the following. Evaluation was made into the number of drilling processes until tool breakage. Table 1 lists the average of the three. Less than 100 are rounded down.
(Drilling conditions)
Tool: Small-diameter drill Work material: Printed circuit board Cutting speed: 94.3 m / min Feed per rotation: 5 μm / rotation Pressure foot pressure: 117 N
Vacuum pressure: 100hPa

From Table 1, Invention Example 1 to Invention Example 26 were superior to Comparative Example 27 to Comparative Example 32 in terms of the adhesion resistance and wear resistance of the workpieces, and therefore were excellent in breakage life. In the film forming method of Example 1 of the present invention, α of ions emitted from the FAIP evaporation source was set to 45 degrees. The Cr metal is used for bombardment and coating of the underlayer, the film thickness is set to 10 nm, and then the amorphous carbon film and a small amount of oxygen are simultaneously introduced. Ionized. As a result of the analysis, the oxygen content of the amorphous carbon film was 0.5%, and the hydrogen content was 5.2%. The number of layers was a two-layer structure including the underlayer, and the film thickness excluding the underlayer was 300 nm. The breakage life by drilling evaluation was 16300 holes, which was superior to the comparative example in breakage life, and satisfactory results were obtained. In Example 2 of the present invention, α of ions emitted from the FAIP evaporation source was 90 degrees. Inventive Examples 3 and 4 show inventive examples when the Co content of the cemented carbide is different. When compared with Comparative Examples 29 and 30, the fracture life was excellent. In Comparative Examples 29 and 30, the cemented carbides had a Co content of 2.5% and 13.5%, respectively, and their breakage life was short due to breakage, abnormal wear, chipping, and the like. From these results, when a cemented carbide is used as the substrate, the Co content is preferably 3% by weight or more and less than 12% by weight. In addition, it was confirmed that effective results could be obtained even with a cermet material and a high-speed steel base material. Invention Examples 5 and 6 show cases where the WC average particle diameters of the cemented carbide are 0.2 and 0.4 μm, respectively, and contain Cr and V. These combinations resulted in excellent breakage life particularly in combination with the amorphous carbon film. Invention Examples 7 to 11 show cases where B and N, F, Cl, S, and N are contained in the nonmetallic components of the amorphous carbon film, respectively. All the samples had excellent breakage life, and were particularly excellent in wear resistance. Invention Example 12 shows a case where the film formation method is only the FAIP method. In this case, oxygen was added by forming a film by the FAIP method while introducing an oxygen-containing gas into the container. It can also be controlled by the pre-deposition pressure. Invention Example 13 is a case where the hydrogen content in the amorphous carbon film is 17.2%, but the number of holes processed is inferior when compared with Invention Example 17 having a hydrogen content of 12.2%. As a result. Therefore, the hydrogen content is 3.6% or more shown in Invention Example 19, and the range of 12.2% or less shown in Invention Example 17 is considered to be a more preferable result. Invention Example 14 is a case where the tool diameter is 1.5 mm. The fracture life was about 2.2 times that of a tool of the same size that was not coated. However, compared with the case of 0.1 mm, the lifetime improvement is not remarkable, and it is more preferable to carry out with less than 1.2 mm. Invention Example 15 shows the case where a Ti film is used for the underlayer. Invention Examples 16 to 20 show cases where an amorphous carbon film and a layer containing a metal component are laminated and coated. As for the method of adding the metal component, Si was added by the PCVD method. Other metal elements were added by simultaneously operating a FAIP evaporation source different from the graphite target. Moreover, the addition method of a metal component is also possible by PCVD method. Invention Example 20 is a laminated film with a layer containing Cr, and shows the case where the number of laminated layers is 800. The film thickness was 1600 nm. Invention Examples 21 to 26 show cases where metal nitride or metal carbonitride is used for the underlayer. Use of these nitride or carbonitride underlayers is particularly effective when the work material contains hard particles. As described above, the examples of the present invention were excellent in breakage life, and satisfactory results could be obtained.
On the other hand, the comparative example 27 shows the case where the coating process is not performed. The fracture life was about 3400 holes. Comparative Example 28 shows a case where the amorphous carbon film is coated only by the PCVD method. It was about 4200 holes. Comparative Example 31 shows a case where the amorphous carbon film does not contain a nonmetallic component. The comparative example 32 shows the case where the oxygen content which is a nonmetallic component of an amorphous carbon film is 28%. In either case, the effect of improving the breakage life was lower than that of the example of the present invention.

FIG. 1 shows a small-diameter drill of Example 1 of the present invention.

Claims (4)

In an amorphous carbon coated cutting tool coated with an amorphous carbon film, the amorphous carbon film contains at least one element of B, Cl, S, P, F, O, and N. The amorphous carbon-coated cutting tool is characterized in that the content of is, in atomic percent, 0.01% or more and 25% or less. The amorphous carbon-coated cutting tool coated with the amorphous carbon film according to claim 1, wherein the amorphous carbon film is produced by a filter-type arc ion plating method or a filter-type arc ion plating method. A method for producing an amorphous carbon film, wherein the coating is performed by a method in combination with a plasma chemical vapor deposition method. 3. The method for producing an amorphous carbon coating according to claim 2, wherein ions from the evaporation source of the filter type arc ion plating method are deflected by a magnetic field, and the deflection angle α (degrees) is 30 ≦ α <90. A method for producing an amorphous carbon film, wherein 3. The method for producing an amorphous carbon coating according to claim 2, wherein at least one of B, Cl, S, P, F, O, and N is added to the amorphous carbon film by a plasma chemical vapor deposition method. A method for producing an amorphous carbon film.

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