WO2009116552A1

WO2009116552A1 - Amorphous carbon covered tool

Info

Publication number: WO2009116552A1
Application number: PCT/JP2009/055228
Authority: WO
Inventors: 護木幡
Original assignee: 株式会社タンガロイ
Priority date: 2008-03-18
Filing date: 2009-03-18
Publication date: 2009-09-24
Also published as: JP5176621B2; JP2009220238A

Abstract

Disclosed is an amorphous carbon covered tool possessing excellent adhesion between an amorphous carbon film and a base material and excellent abrasion resistance. The amorphous carbon covered tool comprises a base material and an amorphous carbon film. The amorphous carbon film comprises an inner layer part on a side in contact with the base material and an outer layer part on the surface side. The content of hydrogen contained in the inner layer part in the amorphous carbon film is 0.5 to 3 atomic%. The content of hydrogen contained in the outer layer part in the amorphous carbon film is less than 0.5 atomic%. The inner layer part in the amorphous carbon film has such a concentration gradient that the content of hydrogen is gradually reduced from the side in contact with the base material toward the surface side.

Description

Amorphous carbon coated tool

The present invention relates to an amorphous carbon-coated tool in which an amorphous carbon film is coated on a base material.

Processing of non-ferrous metals such as aluminum alloys and brass, organic materials, materials containing hard particles such as graphite, and electronic-related printed circuit boards are increasing. In such a work material, since the work material is welded to the cutting edge portion of the cutting tool and the cutting resistance increases, the cutting edge of the cutting tool tends to be lost. Therefore, when cutting these work materials, an amorphous carbon-coated tool is used. As a conventional amorphous carbon-coated tool, there is an amorphous carbon-coated tool in which the amount of hydrogen in the amorphous carbon film is 5 atomic% or less (see, for example, Patent Document 1). Further, a DLC having a two-layer structure of a base layer that substantially does not contain hydrogen and a hydrogen-containing layer that is provided on the base layer and contains hydrogen within a range of 2 atomic% to 20 atomic% ( There is a DLC film-coated tool coated with a diamond-like carbon film (for example, see Patent Document 2). However, these tools have a problem that the adhesion between the coating and the substrate is not sufficient.

JP 2003-62706 A JP 2007-131893 A

For amorphous carbon-coated tools, high-efficiency machining, long life, and improved finishing quality of work materials are required. In order to meet these requirements, an object of the present invention is to provide an amorphous carbon-coated tool that is excellent in adhesion between an amorphous carbon film and a base material and is excellent in wear resistance.

The present inventor has developed an amorphous carbon-coated tool. First, an amorphous carbon film having a large amount of hydrogen is coated on the side in contact with the substrate, and an amorphous carbon film having a small amount of hydrogen is coated on the upper surface thereof. As a result, the present invention was completed with the knowledge that an amorphous carbon-coated tool with excellent wear resistance and excellent adhesion between the amorphous carbon film and the substrate can be obtained. .

That is, the amorphous carbon-coated tool of the present invention includes a base material and an amorphous carbon film, and the amorphous carbon film is composed of an inner layer portion on the side in contact with the base material and an outer layer portion on the surface side. The amount of hydrogen contained in the inner layer portion of the crystalline carbon film is larger than the amount of hydrogen contained in the outer layer portion of the amorphous carbon film.

Examples of the base material for the amorphous carbon-coated tool of the present invention include high-speed steel, cemented carbide, ceramics, and ultra-high pressure sintered body. Among these, cemented carbide is more preferable because it is excellent in hardness and toughness.

The amorphous carbon film of the present invention includes what is called a hard carbon film, a diamond-like carbon film, a DLC film, an aC: H film, an i-carbon film, a ta-C film, and the like.

The amorphous carbon film of the present invention is composed of an inner layer portion in contact with the substrate and an outer layer portion on the surface side. The amount of hydrogen contained in the inner layer portion of the amorphous carbon film is greater than the amount of hydrogen contained in the outer layer portion of the amorphous carbon film. This is because when the amount of hydrogen in the amorphous carbon film is low, the hardness of the amorphous carbon film is high, but the adhesion between the amorphous carbon film and the substrate is low. It is determined from the knowledge that, when the amount is high, the adhesion to the base material becomes high. Among them, when the concentration of hydrogen in the inner layer portion of the amorphous carbon film has a concentration gradient that gradually decreases from the side in contact with the base material toward the surface side, it is possible to prevent adhesion and decrease in coating hardness. More preferable.

The amount of hydrogen contained in the outer layer portion of the amorphous carbon film of the present invention is less than 0.5 atomic%, that is, an amount meaning that substantially no hydrogen is contained, and is contained in the inner layer portion of the amorphous carbon film. More preferably, the hydrogen content is 0.5-3 atomic%. This is because when the amount of hydrogen in the amorphous carbon film is less than 0.5 atomic%, the hardness of the amorphous carbon film is high, but the adhesion between the amorphous carbon film and the substrate is low, and the amorphous carbon film is amorphous. When the hydrogen content of the carbonaceous film is 0.5 atomic% or more, the adhesion to the substrate is increased, but when the hydrogen content of the amorphous carbon film exceeds 3 atomic%, the amorphous carbon film This is because the decrease in hardness becomes remarkable. The amount of hydrogen in the amorphous carbon film and its concentration gradient are measured using elastic recoil detection method (ERDA) using high-energy ions such as helium as incident particles, resonance nuclear reaction method (NRA: Nuclear Reaction Analysis), etc. It can be measured by doing.

The thickness of the inner layer portion in the amorphous carbon film of the present invention is preferably 1 to 10% of the entire thickness of the amorphous carbon film. If the thickness of the inner layer portion of the amorphous carbon film is less than 1% of the entire film thickness, the effect of increasing the wear resistance cannot be sufficiently obtained. The hardness of the entire film decreases. Therefore, the thickness of the outer layer portion of the amorphous carbon film is preferably 90 to 99% of the entire thickness of the amorphous carbon film.

The amorphous carbon film of the present invention preferably has a hardness by nanoindentation of 20 to 100 GPa, more preferably 30 to 80 GPa. This is because if the hardness is less than 20 GPa, the wear resistance decreases, and if it exceeds 100 GPa, the chipping resistance of the cutting edge decreases.

Since the amorphous carbon film of the present invention is easily plastically deformed when the elastic recovery rate is less than 70%, it preferably has an elastic recovery rate of 70 to 100%. Here, the elastic recovery rate of the amorphous carbon film is defined by Equation 1.
[Formula 1] Elastic recovery rate (%) = (Hmax−Hf) / Hmax × 100 (%)
(In the formula, Hmax is the maximum indentation depth, and Hf is the indentation depth (indentation depth) after unloading the load.)

The amorphous carbon film of the present invention preferably has a film thickness of 0.06 to 5 μm. If the film thickness is less than 0.06 μm, the effect of covering the amorphous carbon film cannot be obtained. If the film thickness exceeds 5 μm, the compressive stress of the amorphous carbon film increases, and Adhesion decreases.

In the amorphous carbon-coated tool of the present invention, the compressive stress existing in the base material affects the chipping resistance and the adhesion between the amorphous carbon film and the base material. Regardless of the surface state of the substrate, the compressive stress present in the substrate is preferably 0.3 GPa or less. If the compressive stress of the substrate exceeds 0.3 GPa, chipping is likely to occur in the amorphous carbon film. The compressive stress existing in the base material can be measured by the 2θ-sin ² ψ method, and specifically, the compressive stress of the base material can be measured using the following formulas 2 and 3. Moreover, in the case of the cemented carbide base material which has WC as a main component, the compressive stress which exists in WC can be considered as the compressive stress which exists in a base material.
[Formula 2] Stress σ = -E / (2 ・ (1 + υ)) ・ cotθ ₀・ π / 180 ・ δ (2θ) / δ (sin ² ψ)
[Formula 3] Stress σ = K · δ (2θ) / δ (sin ² ψ)
ψ: Angle between sample surface normal and lattice surface normal σ: Stress (MPa)
E: Young's modulus (MPa)
υ: Poisson's ratio θ ₀ : Standard Bragg angle (degrees)
K: Constant determined by material properties and standard Bragg angle θ ₀

When a Raman spectrum was measured in the range of wave numbers from 800 to 2000 cm ⁻¹ by Raman spectroscopy using an argon gas laser having a wavelength of 514.5 nm, the Raman spectrum of the conventional highly crystalline pyrolytic graphite film was 1580 cm ⁻ Raman peak called single G band appears near ^1. As the crystallinity of the highly crystalline pyrolytic graphite film decreases, a Raman peak called a broad D band appears in the vicinity of a wave number of 1350 cm ⁻¹ .

The amorphous carbon film of the present invention has a first peak in the range of wave numbers 1560 to 1600 cm ⁻¹ and a wave number of 1100 to 1200 cm in a Raman spectrum by Raman spectroscopy using an argon gas laser having a wavelength of 514.5 nm. More preferably, it has a second peak in the range of ^-1 . When the Raman spectrum in the range of wave numbers 800 ~ 2000 cm ^-1 was measured, peaks hardly observed in the vicinity of a wave number of 1350 cm ^-1, if there is a first peak and second peak in the range of the wave number, amorphous It shows a tendency for the hardness of the carbon film to increase.

The amorphous carbon film of the present invention has high hardness comparable to diamond, and exhibits excellent wear resistance when used as a cutting tool. Since the amorphous carbon film of the present invention has a high sp ³ bond ratio, the room temperature hardness and the high temperature hardness are increased.

Specific examples of applications of the amorphous carbon-coated tool of the present invention include cutting tools such as drills, end mills, and throw-away tips, and dies.

The amorphous carbon film of the present invention can be obtained by physical vapor deposition using solid carbon as a starting material. Specific examples of physical vapor deposition include arc ion plating, laser ablation, and sputtering. Among these, the arc ion plating method in which the adhesion between the amorphous carbon film and the base material is high and the hardness of the obtained amorphous carbon film is high is more preferable. Arc ion plating produces carbon ions with a higher ionization rate than other methods, resulting in a dense and hard film with a high sp ³ bond ratio similar to diamond, which greatly improves wear resistance. Can be improved.

In the arc ion plating method, protrusions called microparticles are easily generated on the surface of the amorphous carbon film. The microparticles cause a decrease in wear resistance and a rough surface of the amorphous carbon film, thereby deteriorating the surface quality of the work material. Among the arc ion plating methods, a filtered arc ion plating method that reduces microparticles is more preferable.

Specific methods for producing the amorphous carbon film of the present invention include the following. A tool-shaped substrate is placed in a film forming apparatus, and the surface of the substrate is cleaned with argon plasma. Next, a substrate bias voltage of −30 to −300 V direct current voltage or −30 to −500 V pulse voltage is applied to the substrate to apply one or two of C ₂ H ₂ and CH ₄ to 5 to 20 cm ³ / Introducing into the furnace at a predetermined flow rate in the range of min, and evaporating and ionizing the graphite target by cathodic arc discharge with an arc discharge current of 80 A, the inner layer film of the amorphous carbon film is coated on the side in contact with the substrate. . In order to have a concentration gradient in the amount of hydrogen in the inner layer, it is preferable to reduce the flow rate of one or two of C ₂ H ₂ and CH ₄ with time. When the outer layer portion of the amorphous carbon film is coated without supplying one or two of C ₂ H ₂ and CH ₄ after the coating of the inner layer film of the amorphous carbon film, the amorphous carbon coating of the present invention A tool can be obtained.

The substrate temperature at the time of coating the amorphous carbon film is preferably 50 to 200 ° C., more preferably 50 to 150 ° C. When the substrate temperature exceeds 200 ° C., soft sp ² -bonded graphite is likely to precipitate, and when it is less than 50 ° C., the adhesion between the substrate and the amorphous carbon film is lowered. In the present invention, when the amorphous carbon film is coated, carbon ions are irradiated on the surface of the base material, and the amorphous carbon film is formed, so that the base material temperature rises. In some cases, the substrate temperature may increase.

The amorphous carbon-coated tool of the present invention is excellent in the adhesion between the amorphous carbon film and the base material and in the wear resistance. The amorphous carbon-coated tool of the present invention achieves high-efficiency machining and long tool life, and can improve the finish quality of the work material.

As a base material, a drill made of cemented carbide for processing a printed circuit board having a drill diameter of 0.3 mm × length of 5.8 mm (shape PRM030L-E) was prepared. This substrate was placed in a furnace of an arc ion plating apparatus. While heating the substrate to 300 ° C. using a heater, the inside of the furnace was evacuated to a pressure of 1 × 10 ⁻⁴ Pa. After lowering the set temperature of the heater to 100 ° C. and lowering the substrate temperature to 150 ° C., argon gas is introduced and maintained in an argon atmosphere at a pressure of 2 × 10 ⁻¹ Pa while the substrate is attached by a bias power source. The substrate surface was cleaned with argon plasma with a substrate bias voltage of −400 V applied to the tool.

Next, an amorphous carbon film was formed on the surface of the substrate under the conditions shown in Tables 1 and 2. Table 1 mainly shows conditions relating to the arc ion plating apparatus, and Table 2 shows pulse voltage conditions used for the bias voltage of the base materials of Inventions 5 to 8. For the inventive products 1 to 4, the DC voltage shown in Table 1 was used as the bias voltage of the substrate, and C ₂ H ₂ having a predetermined flow rate of 5 to 15 cm ³ / min was applied at the start of coating the inner layer portion of the amorphous carbon film. It is introduced into the furnace, and the flow rate of C ₂ H ₂ is gradually decreased with time, and adjusted so that the flow rate of C ₂ H ₂ becomes 0 cm ³ / min at the end of coating the inner layer of the amorphous carbon film. The inner layer was covered. The outer layer portion of the amorphous carbon film was coated without supplying C ₂ H ₂ into the furnace. For invention products 5 to 8, the pulse voltage shown in Table 2 was used as the bias voltage of the substrate, and a constant flow rate of C ₂ H ₂ was supplied from the start of coating the inner layer of the amorphous carbon film to the end of coating. The inner layer was covered. The outer layer portion of the amorphous carbon film was coated without supplying C ₂ H ₂ into the furnace.

Comparison product 1 is a cemented carbide drill without coating. In comparative products 2 and 3, a cemented carbide drill base material is placed in a plasma CVD apparatus, and the anode voltage is 100 V, the reflector voltage is 50 V, and the filament current is 30 A. The conditions shown in Table 3 are used on the surface of the base material. An amorphous carbon film was formed.

For the obtained invention products 1 to 8 and comparative products 2 and 3, the depth of the amorphous carbon film using the elastic recoil detection method (ERDA) using high energy ions (helium ions) as incident particles The hydrogen concentration distribution in the direction was measured. The maximum film thickness of the amorphous carbon film was measured using a scanning electron microscope from the cross-sectional observation of the amorphous carbon film. The results are shown in Table 4.

As shown in Table 4, the outer layer portion contains a trace amount of hydrogen of less than 0.5 atomic%, which seems to be mixed from moisture remaining in the furnace. Therefore, it can be said that the outer layer portion of the amorphous carbon film does not substantially contain hydrogen. Next, using a TriboIndentor manufactured by Hysitron, the hardness and elastic recovery rate of the amorphous carbon film were measured at a load of 1 mN. The compressive stress existing in the WC of the substrate was measured under the following stress measurement conditions. These results are shown in Table 5.

[Stress measurement conditions]
Measuring device: Micro-part stress measuring device manufactured by Rigaku Corporation X-ray tube: Cu target collimator: φ2mm
X-ray output: 30 kV, 20 mA
Standard black angle 2θ ₀ : 117 degrees (WC (211) plane)
ψ: 6-point measurement Poisson's ratio of 0 °, 17 °, 24 °, 30 °, 35 °, 40 ° υ: 0.19
Young's modulus E: 700 GPa

The Raman spectra of the amorphous carbon films of Inventions 1 to 8 and Comparative Products 2 and 3 were measured using an argon gas laser Raman spectrometer having a wavelength of 514.5 nm. These results are shown in Table 6.

A drilling test was performed on the obtained drill, and the adhesion state and wear state of the cutting edge were measured. These results are shown in Table 7.

[Drilling test]
Drill diameter: φ0.3mm
Work material: Printed circuit board FR-4 (4-layer board) × 2 sheets Overlap rotation speed: 120,000 rotations / min,
Table feed speed: 3.0m / min
Feed per rotation: 25μm / rev
Number of machining: 3000 holes are machined.

It can be seen that the product of the present invention has superior welding resistance and wear resistance compared to the comparative product. Therefore, the drilling accuracy after drilling is very high, and the service life can be extended.

As a base material, a throw-away tip for milling (K10 equivalent cemented carbide, model number AECW16T3PEFR) was prepared. This substrate was placed in a furnace of an arc ion plating apparatus. While heating the substrate to 300 ° C. using a heater, the inside of the furnace was evacuated to a pressure of 1 × 10 ⁻⁴ Pa. After lowering the set temperature of the heater to 100 ° C. and lowering the substrate temperature to 150 ° C., argon gas is introduced and maintained in an argon atmosphere at a pressure of 2 × 10 ⁻¹ Pa while the substrate is attached by a bias power source. The substrate surface was cleaned with argon plasma with a substrate bias voltage of −400 V applied to the tool.

Next, an amorphous carbon film was formed on the surface of the substrate under the conditions shown in Tables 8 and 9. Table 8 mainly shows conditions relating to the arc ion plating apparatus, and Table 9 shows pulse voltage conditions used for the bias voltage of the substrate. For inventions 9-12, the C ₂ H ₂ at a predetermined flow rate of 6 ~ 12cm ³ / min at the coating start of the inner layer portion of the amorphous carbon film is introduced into the furnace, with a flow rate time C ₂ H ₂ The inner layer portion was coated by adjusting the flow rate of C ₂ H ₂ to 0 cm ³ / min when the coating of the inner layer portion of the amorphous carbon film was completed. The outer layer portion of the amorphous carbon film was coated without supplying C ₂ H ₂ into the furnace. For Inventions 13 to 16, the inner layer portion was coated by supplying a constant flow rate of C ₂ H ₂ from the start of coating of the inner layer portion of the amorphous carbon film to the end of coating. The outer layer portion of the amorphous carbon film was coated without supplying C ₂ H ₂ into the furnace.

Comparative product 4 is a cemented carbide throwaway tip that is not coated. In Comparative Product 5, the base material was put in a furnace of a plasma CVD film forming apparatus, the flow rate of benzene C ₆ H ₆ was 10 cm ³ / min, the pressure was 4.3 × 10 ⁻¹ Pa, the base material temperature was 200 ° C., An amorphous carbon film was formed on the surface of the substrate under the condition of a bias voltage of −1500 V (DC voltage).

For the obtained inventive products 9 to 16 and comparative product 5, the elastic recoil detection method (ERDA) using high energy ions (helium ions) as incident particles was used to measure the depth of the amorphous carbon film. The hydrogen concentration distribution was measured. The maximum film thickness of the amorphous carbon film was measured using a scanning electron microscope from the cross-sectional observation of the amorphous carbon film. The results are shown in Table 10.

As shown in Table 10, the outer layer portion contains a trace amount of hydrogen of less than 0.5 atomic%, which seems to be mixed from moisture remaining in the furnace. Using a TriboIndentor manufactured by Hysitron, the hardness and elastic recovery of the amorphous carbon film were measured under the same conditions as in Example 1. The compressive stress existing in the WC of the substrate was measured under the same conditions as in Example 1. These results are shown in Table 11.

The Raman spectra of the amorphous carbon films of Inventions 9 to 16 and Comparative Product 5 were measured using an argon gas laser Raman spectrometer with a wavelength of 514.5 nm. These results are shown in Table 12.

A milling test was performed on the obtained throw-away insert, and the adhesion state and wear state of the cutting edge were measured. These results are shown in Table 13.

[Milling test]
Work Material: Aluminum Alloy ADC12
Chip shape: AECW16T3PEFR
Cutting speed: V = 300 m / min
Cutting depth: Ad = 5mm
Feed: f = 0.15mm / rev
Down cut

It can be seen that the amorphous carbon-coated tool of the present invention is superior in adhesion between the coating film and the substrate and has excellent welding resistance and wear resistance as compared with the comparative product. Therefore, it is possible to extend the life. Therefore, the amorphous carbon-coated tool of the present invention is an invention with high industrial applicability.

Claims

A substrate and an amorphous carbon film. The amorphous carbon film is composed of an inner layer portion on the side in contact with the substrate and an outer layer portion on the surface side, and the amount of hydrogen contained in the inner layer portion of the amorphous carbon film is An amorphous carbon-coated tool characterized in that the amount of hydrogen contained in the outer layer portion of the amorphous carbon film is greater than the amount of hydrogen.
The amorphous carbon-coated tool according to claim 1, wherein the inner layer portion of the amorphous carbon film has a hydrogen concentration gradient that gradually decreases from the side in contact with the substrate toward the surface side.
The amorphous carbon film according to claim 1 or 2, wherein the amorphous carbon film has a hydrogen content of 0.5 to 3 atomic% in the inner layer portion and a hydrogen content of less than 0.5 atomic percent in the outer layer portion. Coated tool.
The amorphous carbon film has an inner layer portion thickness of 1 to 10% and an outer layer portion thickness of 90 to 99% of the total thickness of the amorphous carbon film. An amorphous carbon-coated tool described in 1.
The amorphous carbon-coated tool according to any one of claims 1 to 4, wherein the amorphous carbon film has a thickness of 0.06 to 5 µm.
The amorphous carbon-coated tool according to any one of claims 1 to 5, wherein the amorphous carbon film has a hardness of 20 to 100 GPa by a nanoindentation method.
The amorphous carbon-coated tool according to any one of claims 1 to 6, wherein the amorphous carbon film has an elastic recovery rate of 70 to 100%.
The amorphous carbon-coated tool according to any one of claims 1 to 7, wherein the compressive stress existing in the substrate is 0.3 GPa or less.
The amorphous carbon film has a first peak in the range of wave numbers 1560 to 1600 cm −1 and a wave number of 1100 to 1200 cm −1 in a Raman spectrum by Raman spectroscopy using an argon gas laser having a wavelength of 514.5 nm. The amorphous carbon-coated tool according to any one of claims 1 to 8, which has a second peak in the range.