WO2008149824A1 - Dlc-coated tool - Google Patents

Abstract

A DLC-coated tool produced by forming a substantially hydrogen-free DLC film on a substrate, wherein the DLC film has a density of 3.0 to 3.4g/cm3 and a nanoindentation hardness of 40 to 100GPa and wherein in the surface scanning test with a stylus type surface profile measuring apparatus provided with a stylus whose point has a radius of curvature of 2μm at a measurement feed of 0.01mm, the ratio of the absolute value of a difference between the arithmetic mean surface roughness of the substrate before film formation and the arithmetic mean roughness of the DLC film to the thickness of the DLC film, ΔRa/t, is 0.05 or below and the ratio of the occupancy area ratio (s) of convexed and recessed parts of the DLC film due to the adhesion or desorption of foreign matter to the thickness (t) of the film, s/t, is 0.01 (%/nm) or below.

Description

 Specification

 D L C Coated Tool Technical Field

 The present invention provides a cutting edge replacement used as a so-called cutting tool such as a turning tool (such as a byte or an end mill), a turning tool (such as a milling tool), or a drilling tool (such as a drill or reamer). Cutting tools, cutting of objects in a broad sense · Cutting tools used for cutting (cutters, knives, slitters, saw blades, etc.), molding tools (punches, dies, etc.) and wear resistance on the surface The present invention relates to a tool and a member formed with a DLC film having anti-adhesion properties. Background art

 When processing work materials such as non-ferrous metals such as aluminum, titanium, magnesium and copper, organic materials, materials containing hard particles such as graphite, maintaining the finished surface shape of the work material, maintaining the hardness of the base material, dimensions Cutting tools are required to maintain high accuracy and so on.

 However, when the work material adheres to the cutting edge of the cutting tool, the cutting resistance increases, and the cutting edge breaks, a problem arises. This is thought to be due to the fact that adhesion to the tool surface is more likely to occur in the case of the above-mentioned work material than in other work materials, and the chipping of the cutting edge due to adhesion and the reduction in machining accuracy are significant. . In view of the above problems, a DLC coated tool having an amorphous carbon film (diamond-like carbon: hereinafter abbreviated as “DLC”) has been studied. '

DLC film contains a lot of sp ² component depending on the ratio of sp ² (graphite structure) component to sp ³ (diamond structure) component and whether it contains hydrogen (H) a — C ((amorphous C arbon; ³ ) Contains many ³ components & -〇 (te t. „R_a_h..e.„ Dera 1 amorphous carbon), each containing H-containing a — C: Classified into 4 types, H and ta_C. Of these, a—C: H has already been put to practical use as a hard protective coating for dies and cutting tools as conventional DLC. DL

C is sometimes called i — C (i-carbon).

 Conventional DLC (a-C: H) film formation is mainly performed by the following method using a hydrocarbon gas as a raw material, that is, an ion source method in which a raw gas is decomposed into a plasma using a hot filament. (Physical vapor deposition method: A type of PVD method) Plasma CVD method that decomposes source gas by direct current or high frequency plasma

 (Plasma assisted C VD method; PE C VD method), plasma ion implantation deposition method, etc. are used.

 However, in these methods, hydrogen contained in the gas is mixed in the film and terminates the bond between carbon atoms, so the hardness decreases.

 On the other hand, the sputtering method or vacuum arc method forms a DLC film (ta — C, a-C) that does not contain hydrogen because the film is formed using solid graphite as a raw material. Can be membrane. In particular, the vacuum arc method does not require a process gas and the ionization rate of the raw material is high, so it is considered that a film having high density and high adhesion can be formed.

Hydrogen-free hydrogen-free DLC-coated tools are disclosed in Patent Documents 1 and 2, and Patent Document 1 describes excellent adhesion resistance, adhesion resistance, and resistance in cutting aluminum alloys and the like. It is said to show weldability. On the other hand, in Patent Document 2, the indentation recovery rate by the nanoindentation method is 0.9 or less, the density is 3.0 g / cm ³ or less, and the film thickness is 0.18 m or less. There is a description that chipping occurs.

Patent No. 3 7 1 8 6 6 4 Specification Japanese Unexamined Patent Publication No. 2 0 0 5-2 2 0 7 3

 In recent years, as materials for work materials, among the aluminum alloys, there are an increasing number of A C-based materials to which Si (Cai) and Cu (Copper), which are alloys for die casting, are added.

 These aluminum alloy materials are increasingly being used in various parts, including engine blocks, for the purpose of reducing the weight of automobiles. In addition, some of these materials have been used in combination with fiber materials.

 However, since these aluminum alloys contain hard Si and carbon fibers, the conventional hydrogen-free DLC film does not provide sufficient hardness, and the DLC film covering the blade edge wears out, so that it can be cut from there. The material starts to stick. For this reason, diamond tools are still used to cut relatively hard, non-ferrous metal materials such as AC materials, composite materials, and copper. However, such a diamond tool has a problem that the coating process is expensive and the manufacturing cost is very high. Disclosure of the invention

 The present invention has been made in order to solve such a problem in a tool for a non-ferrous metal material having a relatively hard hardness. The object of the present invention is to provide a non-ferrous metal such as aluminum, titanium, magnesium or copper. Or, when cutting these alloys, organic materials, materials containing hard particles, printed circuit boards, or mixed members of ferrous materials and soft metals, without causing defects such as chipping, The aim is to provide a DLC coated tool that exhibits high wear resistance and low cutting resistance.

In order to solve the above problems, the present inventors have repeatedly conducted intensive studies on the types of DLC, the film surface shape, the film properties, the film formation method, the film formation conditions, etc. The inventors have found an appropriate range of physical properties such as surface smoothness, density and hardness as a DLC film coated on the tool surface, and have completed the present invention.

The present invention is based on the above knowledge, and the DLC-coated tool of the present invention is formed by forming a DLC film substantially free of hydrogen on a substrate, and the density of the DLC film is 3 0 to 3.4 g Z cm ³ , Nano indentation hardness is 40 to 10 OGP a or less and needle tip curvature radius is 2 μm. 0 In the detection of surface run of 1 mm, the arithmetic average roughness R a (D) of the DLC film surface relative to the arithmetic average roughness R a (S) The ratio AR a Z t (= | R a (S)-R a (D) | Z t) is 0.0.5 Below, the ratio s / t to the film thickness t of the occupying area ratio s of unevenness due to adhesion and Z or desorption of foreign particles on the surface of the DLC film is not more than 0.01 (% / nm). It is characterized by. Brief Description of Drawings

 Figures 1 (a) to 1 (c) are FE-SEM images comparing the surface shapes of DLC films deposited by T_FAD, NFA, and conventional FAD.

 Fig. 2 is a graph showing the relationship between the hardness and Young's modulus of DLC films formed by various deposition methods.

 Fig. 3 is a graph showing the relationship between the film thickness and warpage of a thin plate test piece having a DLC film formed by various film forming methods.

 FIG. 4 is a graph showing a comparison of changes in surface roughness when a DLC film formed by T-F AD and PECC VD is held at a high temperature.

Fig. 5 is a graph showing an example of a Raman spectrum obtained by a He—N e laser with a wavelength of 63.2.8 nm of a DLC film formed by T-F AD. FIG. 6 is an explanatory diagram showing the definition of the chip curl radius and the measuring procedure. Figures 7 (a) to (c) are photographs showing the appearance of typical chips obtained by the cutting test of the example.

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, the DLC coated tool of the present invention will be described in more detail, including its manufacturing method.

The DLC-coated tool of the present invention is formed by forming a DLC film substantially free of hydrogen on a substrate, and the density of the DLC film is 3.0 to 3.4 g Z cm ³ , In the surface scanning detection of 0.1 mm surface scanning with a stylus type surface shape measuring instrument having an indentation hardness of 40 to 1 OOGPa or less and a needle tip curvature radius of 2 m, Arithmetic mean roughness Ra of DLC film surface relative to arithmetic mean roughness Ra (S)

The ratio R a / t (= IR a (S) — R a (D) \ / t) is 0 between the absolute value change amount AR a (nm) of (D) and the film thickness t (nm) of the DLC film The ratio s / t to the film thickness t of the uneven area ratio s due to adhesion and Z or desorption of foreign particles on the surface of the DLC film is less than 0.1 (% / nm). For example, it can be used for cutting non-ferrous metal alloys, organic materials, and materials containing hard particles.

 The DLC coated tool of the present invention includes not only an integrated tool but also a blade-tip replaceable tip. In addition, the DLC film coating treatment may be applied to at least the portion corresponding to the cutting edge of the base material in the cutting tool. In forming tools, it is sufficient that at least the part corresponding to the molding surface of the equipment is coated with a DLC film.

The DLC film used in the DLC-coated tool of the present invention is substantially free of hydrogen, but in the present invention, “substantially free of hydrogen” means that a gas containing hydrogen is intentionally contained in the process chamber. It means that the film was not introduced into the film. However, originally the inner wall and electrode of the vacuum chamber It is difficult to completely eliminate the hydrogen content because gas, dust, or water adhering to and adsorbing on the inside (and inner wall) may be desorbed during the process and mixed into the membrane. The degree is usually 5 atomic% or less.

 At this level, there is no substantial effect on the density, hardness, heat resistance, wear resistance, and adhesion resistance of the protective film. Means 5 atomic% or less. Needless to say, the lower the hydrogen content, the better the adhesion to the substrate, and the closer to 0 atomic%, the better the characteristics, and the more desirable DLC film.

 The gas and moisture in the chamber inner wall and electrode heat the chamber to 100 ° C or higher, or empty the vacuum arc plasma before the film formation process (to generate plasma without film formation. Do not form a film with a shutter, or go straight without bending the plasma. In addition, vacuum arc plasma blanking is effective for removing impurity gas by the getter action, raising the degree of vacuum (lowering pressure), and obtaining a clean process space.

 The hydrogen content of the DLC film can be measured by, for example, glow discharge emission spectrometry (G D O E S) or elastic recoil particle detection (E R D A).

 In the glow discharge emission spectrometry, the coating is processed in the depth direction of the coating by performing high-frequency sputtering of the coating in the Ar glow discharge region and spectroscopically analyzing the radiation from the sputtered atoms. This is a method for elemental analysis. Although it is difficult to measure hydrogen quantitatively by this method, it is possible to know the relative change in the depth direction of the film.

The elastic recoil detection method is a method that measures the energy spectrum of atoms ejected from the surface by entering He ions or H ions at a low angle. Yes, it is one of the few measurement methods that can accurately measure light elements that are difficult to accurately measure by enabling the quantitative analysis of hydrogen by standardizing the spectrum of an arbitrary sample.

 On the other hand, the present inventors have repeatedly investigated the smoothness of the DLC film-forming surface using various film-forming devices. As a result, the main cause of the deterioration of the smoothness of the film-forming surface is a by-product from the cathode when the plasma occurs. The cathode material particles (hereinafter referred to as “droplets”) are found to be found.

 In general, in vacuum arc discharge, vacuum arc plasma constituent particles such as cathode material ions, electrons, and negative material neutral particles (atoms and molecules) are emitted from the cathode spot, and at the same time, the size is from submicron up to several hundred micron. When such droplets are released and attached to the substrate surface, the uniformity and flatness of the DLC film formed on the substrate surface are greatly impaired.

 As described above, the DLC-coated tool of the present invention is a DLC film made of ta-C having substantially a predetermined density and a predetermined hardness without substantially containing hydrogen, before and after the film formation per film thickness. A DLC film having a very smooth surface shape defined by the amount of change in roughness and the occupied area ratio of irregularities is provided on the substrate. Such a smooth DLC film has a droplet on the generated film. By reducing the impact and adhesion of the particles to the limit, contamination of foreign particles represented by the above-mentioned droplets can be eliminated, and protrusion defects due to the adhesion of these foreign particles and depression-like defects due to separation can be minimized. Compared to conventional hydrogen-free DLC, a higher density and higher compressive stress film is put into practical use, and higher wear resistance and adhesion are exhibited.

In the present invention, “foreign particle” mainly means droplets, but it cannot be said that dust or the like does not adhere during handling other than this, and includes these dust particles. Called “foreign particles” To do.

 When forming a DLC film according to the present invention, a filtered arc neutral apparatus is used by using a filtered arc deposition apparatus connected to a film forming process chamber from a plasma source through a plasma magnetic transport duct. This filtered arc vapor deposition system can prevent particles from entering as much as possible, so that the solid droplet emitted from the graphite arc cathode can be trapped and removed at the position facing the cathode. It is desirable to have a let-collecting function, for example, a T-shaped filter door evaporation system (see T 1 FAD: Patent No. 3 8 6 5 5 70) and an X-shaped filtered arc evaporation system ( JP, 2007-07-930, A) can be used.

 That is, the droplets as described above exist on the surface of the non-DLC film formed by the vacuum arc deposition method. In general, the droplet taken into the film increases in proportion to the DLC film thickness. This drop rate in the film lowers the toughness of the film and causes stripping wear, so the higher the film thickness and the higher the interface stress, the smaller the drop rate in the film. Thickening is effective for improving wear resistance as a coating film for tools, but in addition to the problems described above, the surface becomes rough and cutting resistance increases.

 If it is only smooth, the droplet can be removed by polishing after film formation, and the smoothness can be increased, but the hole from which the droplet has been removed remains. In addition to causing adhesion of the work material, this recess also tends to cause peeling, and also increases the coefficient of friction, so it is desirable to reduce this as much as possible.

The evaluation of droplet size should be based on the volume density (l Z rn ³ ) occupied by the droplet relative to the membrane volume. However, since the expected film thickness (~ 1 m) and the size of the droplets are almost the same, the number of droplets on the surface, the amount of change in roughness, the area occupied by the droplets, etc. The value divided by the film thickness can be fully evaluated.

 As a method for evaluating the surface roughness, there is a method for detecting surface scatting using a stylus type surface shape measuring instrument. Although this method is a one-dimensional measurement, it is superior in resolution in the height direction compared to electron microscopes (SEM), etc., and it is easy to evaluate roughness with a macro scale (2 mm). it can'.

 When the roughness is evaluated by the surface scanning detection method using a stylus type surface profile measuring instrument, the absolute value of the arithmetic average roughness R a (D) of the DLC coated surface with respect to the arithmetic average roughness R a (S) of the coated surface The ratio AR a / t (= | R a (D)-R a (S) \ / t) between the value variation AR a (nm) and the DLC film thickness t (nm) is less than 0.1 If it is, sufficient toughness is obtained, and it is more desirable that it is 0.05 or less.

At the same time, the size of foreign particles such as droplets on the surface is also important, and the ratio of the occupied area ratio S of unevenness to the film thickness t due to these must be less than 0.01 (% / nm). When the ratio S / t exceeds 0.01, there are too many droplets in the film, that is, the volume density (1 / m ³ ) occupied by the droplets in the film is high. Too much hardness and elasticity cannot be obtained, resulting in inconvenience that sufficient wear resistance and durability cannot be obtained as a coating for a tool.

 The occupied area of the unevenness can be evaluated by observing F ϋ— S K (F i 1 ed E m i s s i o n — S c a n i n g E l c ct ron M ic c o p e), which is superior in resolution to ordinary SEM.

Take a picture from the direction where the sample surface is tilted at 10 ± 5 degrees from the vertical at a magnification of at least 3, 00 times and capture the drop rate by image processing. If the area ratio is calculated, the unevenness and the area can be evaluated with a small error. It can also be evaluated by directly counting the surface density of the number of irregularities with a diameter of 0.1 m or more.

 Figures 1 (a) to (c) show the T-shaped filtered arc deposition system (T-F).

5 AD), a conventional vacuum arc deposition apparatus (NFA: non-F fi 1 terdarc) without a droplet filter, and a filter duct without a droplet collecting function facing the cathode. The droplet is removed by a pleated paffle placed inside. The rake face and cutting edge of a cutting tip for a milling tool with a DLC ίο film formed by a conventional filtered arc evaporation system (conventional FAD). This shows a comparison of the F F _ S ΕΜ images directly below.

 From these F Ε— S images, the surface of the DLC film (Fig. 1 (a)) by the U-shaped filtered arc vapor deposition device (Τ-F AD) is the same as that of the conventional vacuum arc deposition device (NFA) or the conventional type. Filtered arc evaporation system (conventional F

5) It can be seen that the smoothness is higher than the surface by AD) (Fig. 1 (b) and (c)). In particular, the surface of the DLC by the vacuum arc deposition system (Fig. 1 (b)) has not only the projections indicated by the black circles but also the recesses indicated by the white circles. It can be seen that the surface (Fig. 1 (c)) contains an extremely large amount of particulate foreign matter.

: 0 DLC film irregularities are mainly caused by droplet adhesion and removal, but also dust adhesion and desorption during substrate handling is a secondary cause of DLC film irregularities. Needless to say. Therefore, when practicing the present invention, as a method for reducing the number of irregularities in the DLC film, the substrate should be thoroughly cleaned and the inside of the filtered arc vapor deposition apparatus.

: 5 Careful consideration should be given to sufficient cleaning.

Furthermore, in the filtered arc deposition method, From the viewpoint of reducing the number of projections and depressions due to the drop rate as much as possible, baffles and orifice plates are provided in the plasma magnetic transport duct, and the anode shape is changed to recover the reflection direction of the drop rate. Device control such as directing to the duct, and plasma control such as bending the plasma that has entered the process chamber by an electromagnetic field and forming a film at a position offset from the plasma entrance axis Alternatively, it is important to adopt film forming conditions that suppress the generation of the droplet itself in consideration of the magnitude and waveform of the arc current.

The DLC film formed on the DLC-coated tool of the present invention has a density of 3.0 to 3.4 g / cm ³ , and exhibits good characteristics in application in this region, and the density is high. Is more preferred.

In general, the density of diamond is 3.5 2 g Z cm ³ , and in conventional hydrogen-free DLC, when the density exceeds 3. O g / c ra ³ , the hardness increases and the compressive stress remaining inside It was thought that the adhesion to the base material was impaired and the film was easily peeled off. In addition, since the stress at the interface is proportional to the film thickness, even when the film thickness is increased, it is easy to peel off for the same reason.

However, the DLC film according to the present invention can simultaneously achieve high density, high hardness, high elastic modulus, and high adhesion, and this is because there are very few mechanically weak drop plates in the film, and the drop rate. It is thought that this was realized because there were very few concave defects caused by the desorption or removal of. In other words, many droplets have a glassy carbon or microcrystalline graphite structure, and their density is significantly lower than that of diamond. For this reason, the density becomes 3. Og / cm ³ or more only when the number density of droplets in the film is sufficiently low.

However, when the density of the DLC film exceeds 3.4 g / cm ³ , diamond crystallization starts and the surface roughness increases due to crystallization. This is not preferable because the friction coefficient increases. The density of such a DLC film can be obtained, for example, by X-ray reflectometry (XRR).

 Further, the hardness of the DLC film formed on the DLC-coated tool of the present invention must be in the range of 40 to 100 GPa as measured by the nanoindentation method. There is. That is, if the nanoindentation hardness is less than 40 GPa, there is a problem with wear resistance because of insufficient hardness, while if it exceeds OOGPa, diamond crystallization begins, and the diamond Crystallization increases the surface roughness and increases the coefficient of friction, which is undesirable.

 The nano-indentation method is a type of hardness test, in which a displacement gauge is installed in the indenter drive section and the indentation depth is continuously measured to determine the hardness and Young's modulus. This is a technique with extremely low weight of about 0.1 mN to lN, and capable of accurate measurement even at an indentation depth of 100 nm or less. In the case of a film having a film thickness of Ι μ πι or less and a high elastic modulus, such as the DLC film in the present invention, the microphone mouth Vickers hardness meter or Knoop hardness meter that can only evaluate the hardness after plastic deformation is accurate. Cannot be evaluated.

• Note that the DLC used in the present invention has a very high Young's modulus, which is as high as 400 to 90 GPa. Figure 2 shows a cemented carbide containing a WC average particle size of 0.8 μm, Co content of 10% by weight and 0.3% by weight of Cr on a mirror-finished substrate. The graph shows the relationship between the hardness and Young's modulus of a DLC film formed to a thickness of 700 nm to 100 nm by various film forming methods. T-shaped filtered arc deposition (T-FAD) The DLC film produced by HI exceeds the conventional hydrogen-free DLC, and has the second highest hardness and high elastic modulus after diamond, indicating that it has high wear resistance. In addition, because of its high modulus of elasticity, the film can follow the substrate and wear such as chipping. It has become difficult.

 Furthermore, while conventional permanent-free DLC had these properties, it was difficult to obtain practical adhesion, whereas DLC using the T-FAD method provided + minute adhesion. ing.

 In the figure, P E C VD (P l a s m a E n h a n c e d -C h e m i c a 1 V a o R D e p o s i t i o n) and ^ :,! This is the Wyru Plasma C VD method.

 In addition, for measurement, ENT-1100 type nanoindenter device was used, test load: 9.8 mN, load step: 0.98 mN, load removal speed: 0.98 NZm sec, measurement Number: The condition of 10 points was adopted.

The surface area ratio s of the surface of the DLC film in the DLC coated tool of the present invention must be less than the ratio s / t force S 0.01 (% / nm) to the film thickness t (nm). As described above, the number of protrusions is the ratio N p Z t of the number N p (unit mm ² ) to the film thickness t (mm) with a diameter of 0.1 lm or more per unit area. 1.5 1 0 ⁸ (pieces / ^/ 1 ₁ 1111 3) or less is desirable. That is, if this ratio N p / t exceeds the above value, the volume density (l Zni ³ ) occupied by the droplet is too high to obtain sufficient hardness and elastic modulus, which is sufficient as a coating for a tool. This is because wear resistance and durability tend not to be obtained.

As for the number of recesses, the ratio N h Z t to the film thickness t (mm) of the number N h (piece Zmm ² ) with a diameter per unit area of 0. Ι μ πι or more is 1.0 X 1 0 ⁸ ( Pieces / mm ³ ) or less. If this ratio N h / t exceeds the above value, the resistance to elastic deformation in the transverse direction of the film will be insufficient, which will cause peeling due to the film splitting. If a part of the film is peeled off, the work piece will adhere to the weld, which causes pinning of the tool, which may lead to tool wear and damage. In addition, the number of irregularities and occupied surface The lower the product, the better.

 The thickness of the DLC film formed on the tool substrate is preferably in the range of 10 nm to l ^ m. This is the minimum requirement for completely covering the tool. When the film thickness is 10 nm and the film thickness is increased to more than 1 μπι, foreign particles such as droplets taken into the film increase, resulting in a decrease in surface smoothness and performance. By lowering.

 In the above-mentioned Patent Document 2, it is preferable that the film thickness is thin, and the force S that it is described that chipping or the like of the cutting edge is likely to occur at a film thickness of 0.18 / m or more is described in the examples described later. As shown in the figure, when the above DLC film is coated on a cutting tip and an aluminum alloy is cut, a film thickness of 0.2 111 or more shows excellent cutting performance, especially when Si is added. The force that has been confirmed to be prominent in the cutting of relatively hard aluminum alloys has not yet been clarified.

 Since the D L C film in the D L C coated tool of the present invention has a very high density as described above, a very high internal stress acts on the inside of the film. This has the advantage of suppressing the propagation of cracks as a DLC film for general tools, but if the internal stress is too high, it will cause insufficient film adhesion and cause defects such as chipping. . However, in the DLC film used in the present invention, both high adhesion and high internal stress are compatible, and there is no fear of such defects.

| ¾ «3, length 2 22 mm, width 6 mm, J¾ l mm carbide substrate (WC (ba 1) 1 13.5 wt% C o-lwt% C r / T a) A graph showing the amount of warpage of a specimen against the film thickness when a DLC film is formed by various deposition methods on a polished thin specimen specimen (base material) for stress measurement. Measure and apply DLC film on only one side of the specimen at the same time as the workpiece. After processing, check the warpage and thickness of the center again. W

 15 — Measured and internal stress was calculated from the following equation (1)

Number 1

ED ² S

 3 (1-Iso

 [Where σ is the stress of the film (G P a), is the Young's modulus of the substrate (5 1 7. 5 4 G P a),

 Indicates the Poisson's ratio (0.2 3 8) of the substrate, the thickness is the thickness, Z7 is the total thickness, L is the length of the specimen, and δ is the warp (difference between the warp before and after film formation). ]

 From this, it can be seen that in the DLC film according to the present invention, the ratio y / x of the film thickness x (m) to the warp y (μm) of the test piece is 4.0 or more and 9.0 or less.

 If this value is exceeded and the warpage is large, defects such as chipping will occur, and if it is less than this value, sufficient film strength will not be obtained, causing problems in wear resistance.

 It should be noted that the above region is in the range of 6 GPa or more and 14 GPa or less when converted to the internal stress of the DLC film. .

 In addition, the X-ray stress measurement of the test piece was performed using an X-ray micro part stress measuring machine. Because DLC is amorphous, DLC itself cannot evaluate the buttocks stress with X-rays, but DLC used in the present invention is extremely stressful, so it is possible to measure the stress applied to the substrate side. Combined with the above test piece measurement results, the stress of the film can be estimated.

Based on this, it is possible to investigate the actual film stress of the tool by cutting out a plane part such as the cutting edge of the actual coated tool by several mm ^{2 and} measuring the X-ray stress.

The principle of stress measurement by X-ray is that metal materials are within the elastic limit due to external force. When stress occurs, the crystal lattice spacing (d value) force S shifts in proportion to the magnitude of the stress. When the angle φ between the sample surface normal N and the lattice plane normal N ′ is changed and the change in the diffraction angle (2 Θ) is examined, the stress σ can be obtained by the following equation (2).

Number 2

 [Where σ s is stress (M P a), s is Young's modulus (M P a), v s is Poisson's ratio, Θ. Indicates the standard plug angle (D e g). ]

 Here, K (stress constant) is a constant determined by the material and the diffraction angle. Write a diagram from the measured value (Φ — 2 Θ) to 2 Θ — s ί π 2 φ, find the gradient using the method of least squares, and multiply by to find it uniquely.

 However, the measured value was the peak of WC in the base material, and it does not include the part of the C ο binder included in the ultrafine carbide substrate. In addition, the stress of the substrate is proportional to the total stress of the film, and is considered to increase in proportion to the film thickness. In the case of a cemented carbide substrate, the stress applied to the W C crystal is considered to be basically proportional, although the substrate contains relatively soft C Ο serving as a binder. Even in the case of an iron-based substrate, the internal stress can be estimated by the same method.

 As a result of the measurement, the stress on the base material side also increases almost in proportion to the film thickness. On the other hand, the DLC film-coated substrate formed by NFA, conventional FAD and PECCVD did not show such a peak shift, so it is considered that sufficient stress was not obtained. '' The stress applied to the W C particles of the carbide substrate of the D L C film in the present invention is expressed as y (G

P a), when the film thickness is x (μm), y- _nox is 0.2 or more and 2.0 or less It is desirable that If the above value is not reached, sufficient film stress cannot be obtained, and the film strength is insufficient.If the value exceeds the above value, the toughness of the base material itself is insufficient, and chipping or the like from within the base material. This is undesirable because it can cause defects.

 Regarding the heat resistance of the DLC film, it is desirable that the amount of change in the arithmetic average roughness Ra of the DLC film after holding for 1 hour in the atmosphere at 60 ° C is 0.05 μm or less. .

That is, Fig. 4 shows that the WC average particle size is 0.8 μm and the Co content is 10 weights. /. The Cr content is 0.3 wt. / ₀ , Carbide specimen with mirror finish made of residual WC is used as a base material, and T-shaped filtered arc deposition (T-F AD) and plasma C VD (PEC VD) After coating with DLC, hold it in the atmosphere at each temperature from 20 ° C to 100 ° C at 60 ° C for 1 hour, return to room temperature after heating, and then surface each film The result of measuring the shape is shown in comparison with the non-coated case.

As a result, the DLC film formed by the T-shaped filtered arc deposition method shows almost no change, whereas the uncoated specimen and the sample coated with DLC by the plasma CVD method are super The result was that the hard substrate carbon was desorbed and the surface was rough. The PECVD method contains hydrogen in the film, which is to detach from 5 0 0 ^D C before and after film is destroyed. As a result, the base material was in contact with air and showed the same change as untreated. In contrast, the DLC film by T-shaped filtered arc deposition shows high heat resistance, and a slight residual drop rate burns and the degree of smoothness changes slightly. But it showed no abnormality. In the case of a film with a roughness change of 0.05 μm or more, defects will occur in the film due to droplet combustion. For this reason, the film hardness decreases rapidly, and it may not be possible to maintain sufficient wear resistance as a tool coating. It ’s not good.

 When applied to a cutting tool, it is extremely important that the tool coating is able to withstand the temperature rise of the cutting edge, especially in dry cutting. In the case of aluminum alloy, melting is usually said to start at about 60 ° C, and the cutting edge is considered to have risen locally to this temperature. Therefore, a tool with a DLC film that can withstand temperatures of 600 ° C is extremely effective as a non-lubricated (dry) aluminum alloy cutting tool.

 In the DLC-coated tool of the present invention, it is desirable that the peak energy of the plasmon loss spectrum of the DLC film formed on the substrate surface is 29 to 33 eV.

 The plasmon excitation spectrum can be measured by electron energy loss spectroscopy (E E L S: E l e c t r n E n e r g y—L o ss S p c t r o s copy). E E L S means that when electrons with energy of several hundred eV are incident on the sample surface, the incident electrons depend on the electron density of the solid and the arrangement of atoms.

It is inelastically scattered and loses energy, so it is a method of spectroscopy of the loss of electron energy. The spectrum measured by EELS is called the EELS spectrum, and the spectrum due to plasmon excitation caused by the collective oscillation of free electrons appearing in the range of 10 to 50 eV is the plasmon excitation spectrum. Toru is called. The peak position of the plasmon excitation spectrum is the square root of the electron density.

Since it is proportional to I, a high peak position means that the electron density is high, and hence the atomic density is high.

Therefore, the peak position of the plasmon excitation spectrum being 28-33 keV indicates a high-density film. Since the peak positions of the plasmon excitation spectra of the graph and diamond are 26 eV and 33.7 eV, respectively, impurities such as hydrogen and relatively low-density impurities can be used. Do not include a droplet Only in the case of DLC, the peak position of the plasmon excitation spectrum is 29-33 keV. Furthermore, the higher this value is, the higher the density is, and it is suitable as the DLC of the present invention, which can obtain a sufficient hardness as a tool coating.

 When the above lower limit is not reached, the density is low and sufficient hardness cannot be obtained, and when the upper limit is exceeded, a diamond crystal region is obtained, and a smooth surface is not obtained with diamond crystal, and the frictional resistance is also high. turn into.

In the DLC-coated tool according to the present invention, the DLC film formed on the surface of the base material is a Raman spectroscopic spectrum using a laser having a wavelength of 6 32.8 nm. It has a characteristic band with a peak between 200 cm- ¹ and the area intensity ratio of D and G is less than 0.8, and the peak intensity ratio between the characteristic band and D band The area intensity ratio is preferably 0.15 or more.

 In other words, Fig. 5 shows the Raman spectrum of a DLC film by T-shaped filtered arc deposition using a He_Ne laser with a wavelength of 6 32.8 nm.

An example of (Raman shift) is shown below. Similar results were obtained when a semiconductor Darlens laser with a wavelength of 5 3 2 nm was used.

In general, it is difficult to specify the film structure because DLC is amorphous, but it is known that characteristic peaks can be obtained by Raman spectroscopic analysis, which is elastic scattering by lattice vibration of light. In particular, the E 2 g mode of the in-plane vibration of the graph eye that appears in the vicinity of ¹ 560 cm ¹ and the G band, which is the peak of the superposition of the degenerate mode, and 1 3 60 cm— ¹ It is well known that there is an A 1 g mode due to asymmetry at the crystal edge of the graph eye that appears in the vicinity, and a D band that is a superposition peak of the mode and the appropriate mode.

In the DLC film of the present invention, in addition to these peaks, It was newly found that a new characteristic band (hereinafter referred to as “S band J”) having a peak in the vicinity of 1 0 0 c in— ¹ appears.

 Furthermore, when the area intensity ratio (S dZ S g) of D and G Pand is less than 0.8, there are few graph items and their microcrystalline state, and the peak intensity ratio between S and P bands. If (I s / I d) and area strength ratio (S s ZS d) are both 0.15 or less, the DLC film will be extremely hard, and the tool coating will have excellent wear resistance. Become.

In other words, the newly discovered S-band coincides with the T-pand peak detected by the conventional ultraviolet laser, so it is judged that the S-pand is identical to the T-band and shows the sp ³ structure. it can. Therefore, the fact that S Pand = T Pand was detected by Raman spectroscopy using a visible light laser means that the drop rate consisting of sp ² structures has been removed to the limit and that there are extremely many sp ³ structural components. ing. In other words, if the S-band can be detected by Raman spectroscopy of a visible light source, the droplet is removed to the limit, it is an extremely flat DLC film with no irregularities, it contains virtually no hydrogen, and it has nanoindentation hardness. S 40-: LOOGP a, which is nothing but a DLC film having a density of 3.0-3.4 g / cm ³ .

 A typical example of the substrate in the DLC-coated tool of the present invention is a WC-based carbide substrate. This WC cemented carbide is composed of a hard phase mainly composed of tungsten carbide (WC) and a binder phase mainly composed of an iron group metal such as cobalt.

Since the DLC film applied to the present invention has the second highest elastic modulus after diamond, it can also be applied to ultra-fine carbide substrate with a large amount of cobalt having high toughness, which has been difficult in the past. The cobalt content of the base material exhibiting stable adhesion without peeling off such a DLC film is 0 to 25% by mass, more preferably 5 to 15%. Also, WC average particle size is It is preferably 1.5 μπι or less. The base material used in the tool of the present invention is not limited to cemented carbide, but is a kind of iron-based alloy, high-speed steel defined in JISG 440.3, carbon tool steel (JISG 4 4 0 1), alloy tool steel (JISG 4 4 0 4), cermet material, c BN-containing sintered body can be coated.

 In the DLC coated tool of the present invention, it is preferable to provide an intermediate layer between the substrate and the DLC film from the viewpoint of strengthening the adhesion of the DLC film.

 Between the DLC film and the substrate, a metal film, a non-metal solid film, a nitride film, a hydride film, an oxide film, or a hydride film having a thickness of 0.1 to 500 nm. , Selected from the group consisting of oxycarbide film, oxyhydrocarbon film, oxynitride film, oxynitride oxyhydride film, nitrocarbide film, nitrocarbide film, oxynitride carbide film, and oxynitride oxycarbide film It is desirable to have an intermediate layer consisting of at least one of the above-mentioned intermediate layers, and between the intermediate layer and the DLC film, a chemical composition obtained by mixing the respective coating compositions or a continuously altered chemical composition. It is even more desirable to obtain a stronger adhesion by interposing the above film.

 When the manufacturing conditions are switched between the formation of the intermediate layer and the formation of the DLC film, usually, the intermediate layer and the DLC film are slightly mixed, and a coating layer having the above-mentioned mixed chemical composition is formed.

 Such a mixed chemical composition layer is difficult to confirm directly, but from the results of the profile in the depth direction of the film by XPS, X-rayphoto-electronic Spectroscopy (AES), AES (Auger Electron Spectroscopy), etc. It can be estimated sufficiently.

The DLC coated tool of the present invention is particularly suitable for its wear resistance and adhesion resistance. Suitable for tools for machining minium and its alloys. It is also optimal to use for non-ferrous materials such as titanium, magnesium and copper and their alloys. In addition, cutting materials such as graphite and other hard particles and fibers such as glass, organic materials, printing circuit board processing and glass processing, and co-machining processing of ferrous materials and aluminum Is also effective. In addition, since the DLC film in the present invention has a very high hardness, it can be used not only for non-ferrous materials but also for processing steel products such as stainless steel.

 The DLC-coated tool of the present invention has high cutting performance, so that it can be used for drills, end mills, end milling cutting edge replacement inserts, milling cutting edge replacement inserts, turning cutting edge replacement inserts, metal saws, It can be used for cutting tools such as toothpaste, reamer and tap. In addition, because of its excellent wear resistance and adhesion resistance, it can be used for applications such as molding punches and dies.

 As an index of the machinability of the DLC coated tool of the present invention, attention is paid to the curl diameter of chips obtained during dry cutting of an aluminum alloy.

 For example, a chip substrate made of WC-based cemented carbide (Sumitomo Electric hard metal chip, model number: APET 1 6 0 5 0 8 PDFR—S, chip material: HI) with the above DLC coating When using the inventive tip and body (Sumitomo Electric End Mill, Model No .: WEM 3 0 2 5), when cutting within the recommended cutting conditions specified by the manufacturing force of the base tool shown in Table 1, It was found that when the obtained chip curl radius was 0.7 times or less the chip curl radius of the same chip not treated with DLC, adhesion of aluminum to the cutting edge was difficult to occur.

table 1 Sumitomo Electric hard metal

 Tool

 Body model number: WEM3025 (25)

 Sumitomo Electric hard metal

 Base material Chip model: APET 160508PDFR-S Chip material: H 1 (WC-Co)

 Alloy type A 5052 AC4 A-T 6 ADC 1 2 Material

 St content (at 0 8 ~ 10 9. 6 ~ 12 Cutting speed (tn / min) 300

 Feed amount of 1 blade contact (bleach / tooth) 0.15

 Axial depth of cut (Conference) 5

 Radial depth of cut (Conference) 5

 No cutting oil (Air blow)

The chip has better curl radius depending on the friction coefficient between the cutting tool surface on the rake face side and the work material. The smaller the radius, the better. Chips also remove the heat of the cutting edge, and chip discharge is one of the important factors that determine cutting tool performance. The smaller the curl radius, the better the discharge.

 The DLC coated tool of the present invention has high chip discharge performance even for aluminum alloys such as AC 4 A and AD C 12 to which Si has been added, which has been difficult in the past. It is desirable that the chip curl radius obtained using the tool is not more than 0.7 times the chip curl radius of the untreated DLC coated tool.

Regarding the chip curl radius, as shown in Fig. 6, the starting point of the free curved surface side of the chip free curved surface (the surface cut by contact with the tool rake face) is A, and the tangent line that touches A is the X axis. Draw a Y-axis that passes through A and goes straight to the X-axis, and further intersects the chip free-form surface and the Y-axis (if there are two or more points, the Select B where the thickness is the thickest). Then, draw a circle with the line AB as the diameter, and use that radius as the chip curl radius.

 In addition, regarding the cutting resistance at the time of dry cutting of the aluminum alloy specified as A 5 0 5 2 in JISH 400, the cutting resistance by the DLC-coated tip of the present invention at the initial stage of cutting is the DLC. The ratio of cutting force due to uncoated chips to the cutting force is 0.6 or less for the main component force, 0.7 or less for the back component force, and 0.7 or less for the resultant force of the main component, the back component force and the feed component force It is desirable to be.

 The cutting resistance can be measured by, for example, a piezoelectric cutting dynamometer (Kistler). “Initial cutting” specifically means that the cutting length is within 0.1 m from the start of cutting.

Example

 Hereinafter, the present invention will be specifically described based on examples. In addition, this invention is not limited at all by these Examples.

 As a base material, prepare a base material for chips made of WC-base cemented carbide (chip made by Sumitomo Electric Hard Metal, model number: APET 1 6 0 5 0 8 PDFR—S, chip material: HI) On the substrate, a DLC film was formed using a T-shaped filtered arc vapor deposition apparatus (T-FAD), and Samples 1 to 5 corresponding to the product of the present invention were produced.

 On the other hand, a conventional vacuum arc deposition device without a droplet filter (NFA, a conventional filtered arc deposition device (formerly FAD), and a plasma CVD device (PEC VD) are used on the substrate. Each DLC film was formed, and samples 6 to 10 corresponding to the comparative examples were produced.For sample 10, the DLC film was not formed, and the one-way chip as a base material was used. did.

And various kinds of DLC films formed on the obtained thrower chip Physical properties and surface shape were measured.

 Then, a cutting test of three kinds of aluminum alloys was conducted under the conditions shown in Table 1. Chips after cutting 7 m were collected, and the curl diameter was measured according to the procedure shown in FIG. The adhesion width to the cutting edge and the cutting resistance were measured with a kissler.

 These results are shown in Tables 2-4.

 In addition, as a representative example of chips from the cutting test, the appearance of the chips of aluminum alloy ADC 1 2 using the tips of Sample 3, Trial 6 and DLC-uncoated sample 10 is shown in Fig. 7 (a ) Shown in (b) and (c), respectively.

Table 2

As is clear from the results in Tables 2 to 4, the chips from the DLC coated tools of Samples 1 to 5 corresponding to the present invention are hardened with S i AD C 1 2 and A C

Good cutting ability even when cutting aluminum alloy materials such as 4 A A 5 0

5 2 is the same and shows a small curl radius stably. On the other hand, conventional DLC films formed by FAD and NAD are inferior in density, hardness, and smoothness of the film surface. Chips from tools coated with such DLC films are A 5 0 5 2 However, it was confirmed that cutting with AD C 12 and AC 4 A had almost the same performance as uncoated tools. In addition, the DLC coated tool of the present invention is superior to conventional products in cutting AD C 12 and AC 4 A, and the curl radius of chips is about 0.7 times less than that of untreated chips. It has become.

 Furthermore, with respect to the cutting resistance with respect to A 5 0 52, the DLC coated tool of the present invention shows the minimum cutting resistance from the beginning of cutting.

 In aluminum alloy cutting, it is suggested that the coefficient of friction is proportional to adhesion crushing, and the adhesion width after 7 m cutting is also generally reduced in proportion to the curl radius and cutting resistance.

 The DLC-coated tool of the present invention is superior in density, hardness, and film surface smoothness to the conventional hydrogen-free DLC film (samples 6 to 8) shown in the comparative example. For a wide range of work materials, it was found that chips were discharged well, cutting resistance was low, and adhesion resistance was excellent.

Industrial applicability

According to the present invention, the DLC film formed on the grave material is substantially free of hydrogen, is a DLC film classified as ta—C having a predetermined density and nanoindentation hardness, and Ratio of change in arithmetic average roughness of film surface after film formation to DLC film thickness relative to arithmetic average roughness of substrate surface before film formation by needle-type surface shape measurement, and adhesion of foreign particles such as droplets Or due to omission The ratio of the uneven area on the surface of the DLC film and the film thickness ratio were specified to make the surface smoothness limit value, or the DLC film formed on the substrate had a wavelength of 6 3 2.8 nm The Raman spectroscopic spectrum using a laser has a characteristic band with a peak between 1 0 0 0 and 1 2 0 0 cm— ¹ and the area intensity ratio between the D and G bands is both It is assumed that the peak intensity ratio and area intensity ratio between the characteristic band and the D band are 0.15 or more because of high wear resistance and low cutting resistance. It can be a cover tool.

Claims

The scope of the claims 1. A DLC-coated tool formed by forming a DLC film substantially free of hydrogen on a substrate, wherein the DLC film has a density of 3.0 to 3.4 g / cm ³ and a nano indentation. In the surface scanning detection of 0.01 mm surface scanning with a stylus type surface shape measuring instrument having a hardness of 40 to 10 OGPa or less and a needle tip curvature radius of 2 μm, The absolute value change AR a (nm) of the arithmetic average roughness Ra (D) of the DLC film surface relative to the arithmetic average roughness Ra (S) of the film formation surface before the film and the film thickness t of the DLC film R a Z t (= IR a (D)-1 R a (S) \ / t) is 0.1 or less, and the adhesion and Z or desorption of foreign particles on the DLC film surface A DLC-coated tool characterized in that the ratio s Z t of the occupying area ratio _s due to unevenness to the film thickness t is 0.0 1 (% Z nm) or less. 2. Of the irregularities on the surface of the DLC film, the ratio N p Z t of the number of convex parts with a diameter of 0. Ι μ πι or more Ν ρ (piece Zmm ² ) to the film thickness t (mm) is 1.5 X 1 The D L'C coated tool according to claim 1, characterized in that the number is 0 ⁸ (piece Zmm ³ ) or less. 3. Of the irregularities on the surface of the DLC film, the ratio of the number of recesses with a diameter of 0. 0 μ ιη or more N h (pieces Zmm ² ) to the film thickness t (mm) N h Z t is 1.0 X 1 0 The DLC-coated tool according to claim 1 or 2, wherein the number is ⁸ (pieces / mm ³ ) or less. 4. The DLC-coated tool according to any one of claims 1 to 3, wherein the thickness of the DLC film is 1 O nm to l μηι. 5. The DLC coating tool according to any one of claims 1 to 4, wherein the DLC film has a compressive stress, and the internal stress is 6 to 14 GPa. 6. The amount of change in the arithmetic average roughness R a of the DLC film after holding for 1 hour in the atmosphere at 60 ° C. is not more than 0.05 μπι. DLC coated tool according to any one of the sections. 7. The DLC coated tool according to any one of claims 1 to 6, wherein the peak energy of the plasmon loss spectrum of the DLC film is 29 to 33 eV. 8. A DLC-coated tool formed by forming a DLC film substantially free of hydrogen on a substrate, in a Raman spectroscopic spectrum using a laser having a wavelength of 6 3 2.8 nm. 1 to 100 cm with a characteristic band having a peak between ¹ , the area intensity ratio of D band and G band is 0.8 or less, and the characteristic band A DLC coating tool characterized in that both the peak intensity ratio and the area intensity ratio with the D band are 0.15 or more. 9. The DLC coated tool according to any one of claims 1 to 8, wherein the base material is an iron-based alloy. 10. The DLC-coated tool according to any one of claims 1 to 8, wherein the base material is a cemented carbide. 1 1. Ratio y / x of stress y (GPa) to film thickness x (μm) applied to WC particles of cemented carbide substrate by coating DLC film is in the range of 0.2 to 2.0 The DLC-coated tool according to claim 10, wherein 1 2. Metal film, non-metal solid film, nitride film, hydride film, oxide film, acid film having a thickness of 0.1 to 500 nm between the above substrate and DLC film From hydride film, oxycarbide film, oxyhydrocarbon film, oxynitride film, oxynitride oxyhydride film, nitrocarbide film, nitrocarbide film, oxynitride oxynitride film and oxynitride oxycarbide film The DLC coated tool according to any one of claims 1 to 11, further comprising an intermediate layer made of at least one selected from the group consisting of: 1 3. The DLC film according to any one of claims 1 to 12, wherein the DLC film is coated at a position facing the cathode and facing by a filter door deposition apparatus having a droplet collecting means. DLC coated tool as described in section. 1 4. Feature of drill, end mill, tip changeable tip for milling, tip changeable tip for frying, tip replacement tip for turning, metal saw, toothing tool, reamer, or tap The DLC-coated tool according to any one of claims 1 to 13. 1 5. Aluminum alloy material A 5 0 5 2, AC 4 A (T 6 treatment) and ADC 1 2 cut when dry cutting is performed as the work material The ratio of the scrap curl radius to the force radius of the DLC-coated untreated chips is 0.7 or less, any one of claims 1 to 14 DLC coated tool as described in one section 1 6. When aluminum alloy material A 5 0 5 2 is dry-cut as the work material, the ratio of the cutting resistance to the cutting resistance due to the DLC-coated untreated chip at the initial stage of cutting is 0 as the main component force. 6 or less, the back component force is 0.7 or less, and the combined force of the main component force, the back component force and the feed component force is 0.7 or less. DLC coated tool according to item. 1 7. The DLC coated tool according to any one of claims 1 to 13, which is a punch or die for molding.