JPH08170167A - Hard coating film excellent in wear resistance and hard coating film coated member - Google Patents

Abstract

PURPOSE: To impart superior wear resistance by forming a hard coating film of a compd. of Al, Ti and Si as metallic elements and C and N as nonmetallic elements having a specified compsn. on the surface of a substrate and coating the surface of the hard coating film with boron nitride. CONSTITUTION: A hard coating film consisting of two layers is formed on the surface of a substrate. The 1st layer is formed on the substrate side and has a chemical compsn. represented by the formula (Alx Ti1-x-y Siy ) (Cz N1-z ) (where 0.05<=x<=0.75, 0.01<=y<=0.1 and 0<=z<=0.4). Boron nitride is laminated as the 2nd layer on the surface of the 1st layer. The thicknesses of hard coating films as the 1st and 2nd layers are preferably regulated to 0.1-20μm each. Since the BN coating film having high hardness, excellent in oxidation resistance and having a low coefft. of friction has superior affinity for and reactivity with the (Al, Ti, Si) (C, N) coating film and does not deteriorate the adhesion of the (Al, Ti, Si) (C, N) coating film to the substrate, hardness and oxidation resistance as the entire hard coating film are enhanced and wear resistance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention requires a surface coating material for a cutting tool used for milling, cutting, piercing, etc., or high hardness such as a die, a bearing, a die and a roll. A hard coating useful as a surface coating for wear-resistant members, or a surface coating for heat-resistant and corrosion-resistant members such as screws and cylinders for molding machines, and further exhibiting excellent wear resistance by coating the hard coating. The present invention relates to a hard coating member.

[0002]

2. Description of the Related Art Cutting tools that require high wear resistance, such as high speed tools and cemented carbide tools, require TiN on the surface of the base material of the tool.
Wear resistance is improved by forming a hard coating such as TiC or TiC.

Comparing the wear resistances of TiN and TiC described above, TiN is superior to TiC in terms of oxidation resistance in a high temperature range, and is resistant to crater wear on the tool rake face caused by working heat and friction heat during cutting. And exhibits good wear resistance. Moreover, TiN is also excellent in adhesion to the base material. On the other hand, TiC has a higher hardness than TiN, and has high durability against flank wear of the flank contacting the work material.

However, even TiN, which is excellent in oxidation resistance, has an oxidation start temperature of about 600 ° C. at most, and even TiC having high hardness has a Vickers hardness of about 2000 at most. Further improvement in wear resistance has been desired.

Therefore, for example, in Japanese Patent Laid-Open No. 2-194159, for the purpose of improving the oxidation resistance and hardness of TiN and TiC, a composite nitride or a composite carbonitride of Al and Ti in which a part of Ti is replaced by Al is disclosed. Hereinafter, it is indicated as (Al, Ti) (C, N)], the oxidation start temperature is improved to about 800 ° C., and the Vickers hardness is improved to about 2500.

The present inventors have also found that by substituting some elements with other elements based on the compound of Al and Ti and N, they have high hardness and good oxidation resistance and excellent resistance to oxidation. We have developed a hard coating that exhibits wear resistance and have already filed an application. For example, an (Al, Ti, Si) (C, N) film (Japanese Patent Application No. 6-100154) has an oxidation start temperature of about 10
The temperature is 00 ° C., and the Vickers hardness is about 3100.

Further, Japanese Patent Laid-Open No. 4-120265 discloses a cBN having a high hardness of Hv3500 or more.
As a technique for solving the problem that it is difficult to form (cubic boron nitride) on an abrasion resistant substrate with good adhesion, an intermediate layer such as TiN is formed between the substrate and the cBN film. Discloses an invention for coating a cBN film with good adhesion. Certainly, the intermediate layer made of TiN has excellent adhesion to the base material, and the intermediate layer and cB
Since the N film has high adhesion, the cBN film does not easily peel off. However, the cBN film is Hv350
Despite having a high hardness of 0 or more, T
When formed on an intermediate layer such as iN, the hardness of the intermediate layer was low, so that the high hardness as expected for the cBN film was not obtained, and the oxidation resistance was also insufficient.

Under such circumstances, it is expected that a hard coating having more excellent abrasion resistance will be developed in the fields such as cutting, where higher efficiency is required.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and exhibits more excellent wear resistance while taking advantage of the excellent characteristics of the hard coatings developed so far. It is an object of the present invention to provide a hard coating, and further to provide a hard coating-coated member obtained by coating the above hard coating on a member that requires high wear resistance.

[0010]

The hard coating according to the present invention, which has achieved the above object, is a hard coating formed on the surface of a base material, and has a first layer and a second layer. The layer is formed on the base material side, and (Al _x Ti _1-xy Si _y ) (C _z N _1-z ) where 0.05 ≦ x ≦ 0.75 0.01 ≦ y ≦ 0.1 0 ≦ The gist is that it has a chemical composition represented by z ≦ 0.4, and the second layer is BN laminated on the surface side. still,
The above variables x, y, and z are all atomic weight ratios.

The thickness of the hard coating is the same as that of the first layer and the second layer.
It is preferable that both layers have a thickness of 0.1 to 20 μm. By forming the hard coating on the surface of the base material, a hard coating member having excellent wear resistance can be obtained.

[0012]

The present inventors have developed the above (Al, Ti, Si) (C,
N) As a result of repeated studies for the purpose of further improving the wear resistance of the system coating, the above (Al, Ti, Si)
By forming a BN film as a protective layer on the surface of the (C, N) -based film with good adhesion, the hardness and oxidation resistance of the hard film as a whole can be increased, and the wear resistance of the hard film is greatly improved. I figured out what I could do.

The reason why the hard coating of the present invention can exhibit superior wear resistance as compared with the conventional hard coating has not been fully clarified, but it is considered as follows. That is, by forming a BN film having high hardness, excellent oxidation resistance and a small friction coefficient as a surface layer on the (Al, Ti, Si) (C, N) -based film with good adhesion, The Vickers hardness can be as high as 4000 or more and the lower layer (Al, Ti, Si)
It is considered that this is because the protective film made of Al oxide formed on the surface of the (C, N) -based film is significantly densified.

The BN film is composed of (Al, Ti, Si)
Since it has excellent affinity and reactivity with the (C, N) -based coating, it can be formed with good adhesion on the underlying (Al, Ti, Si) (C, N) -based coating, and ( Al, T
Since it does not impair the adhesion between the (i, Si) (C, N) -based coating and the base material, the problem of peeling at each interface even when applied to the surface of a cutting tool or other wear resistant member It is possible to obtain a hard film-coated member that is less likely to occur and that sufficiently exhibits excellent wear resistance of the hard film.

In the present invention, the BN film is the underlayer (Al, T
The reason why the i, Si) (C, N) -based film can be formed with good adhesion remains unclear, but for example, JOURNAL OF HARD MATERIALS (Vol.2, No.3-4, 1
991, P233-243), it seems that a reaction layer of AlN, TiN, TiB ₂ or the like is formed at the interface of the cBN-TiAlN composite material, and even in the case of the present invention, (Al, T
It is considered that a similar reaction layer is formed at the interface between i, Si) (C, N) and BN, and thereby the adhesion is remarkably enhanced.

In the hard coating film according to the present invention, the first layer formed on the substrate needs to have the following chemical composition. (Al _x Ti _1-xy Si _y ) (C _z N _1-z ) where 0.05 ≦ x ≦ 0.75 0.01 ≦ y ≦ 0.1 0 ≦ z ≦ 0.4

(Al _x Ti _1-xy Si _y ) (C _z N
_1-z ) has excellent wear resistance, the values x and y in the component composition Al _x Ti _1-xy Si _y of the metal element are 0.05 ≦ x ≦ 0.75,0.01, respectively. It is necessary to satisfy the condition of ≦ y ≦ 0.1. The value of x is 0.05
If it is less than or less than 0.01, the sufficient effect of improving the oxidation resistance cannot be obtained. Further, when the value of x exceeds 0.75 or the value of y exceeds 0.1, the crystal structure of the coating changes from cubic to hexagonal and the coating hardness decreases, resulting in sufficient wear resistance. I can not get sex.
The lower limit of x is preferably 0.25 and 0.5
It is more desirable that it is 6 or more. The upper limit of x is preferably 0.7. The preferable lower limit value of y is 0.02, while the upper limit value of y is preferably 0.08, and 0.
It is more desirable that it is 05 or less.

The first layer of the hard coating according to the present invention exhibits excellent wear resistance regardless of whether it is a nitride of the above metal element or carbon / nitride. However, in C _z N _1-z , z
If the value of exceeds 0.4, the oxidation resistance of the film decreases, so it is desirable to satisfy 0 ≦ z ≦ 0.4.
Incidentally, when the value of z is 0.2 or less, the oxidation resistance becomes better.

The present invention does not limit the composition or crystal structure of the BN film formed as the second layer, but if cBN or hard BN having a hardness of Hv3500 or more is laminated on the first layer, high wear resistance is obtained. Is obtained, which is preferable.

Next, the thickness of the hard coating according to the present invention is 0.1 μm or more and 20 μm or more for both the first layer and the second layer.
The following is desired. If it is less than 0.1 μm, the wear resistance cannot be sufficiently exhibited, while if it exceeds 20 μm, the hard coating may be cracked by the impact force.

When a hard coating according to the present invention is coated on a cutting tool, it is desired to make use of the original cutting edge characteristics of the tool base material while at the same time exhibiting excellent wear resistance of the hard coating. . From such a viewpoint, the thickness of the hard coating according to the present invention is preferably 1 μm or more, and more preferably 2 μm or more, for both the first layer and the second layer. The upper limit is preferably 12 μm or less, and 8
It is more desirable that the thickness is less than or equal to μm.

Further, although the present invention does not limit the material of the base material coated with the hard coating, in order to achieve excellent wear resistance by coating the surface of the base material with good adhesion, a cemented carbide is used. Hard materials such as high speed tool steel, die steel, cermet or ceramic are suitable.

When the hard coating according to the present invention is applied to the surface of the substrate, a PVD method typified by an ion plating method and a sputtering method can be given as a method for forming the first layer. When the arc discharge type ion plating method is adopted, the method exemplified below may be used. That is, metal components (Al, Ti, Si) are ionized from the cathode, which is an evaporation source, by arc discharge and ion-plated in a N ₂ atmosphere and / or a CH ₄ atmosphere to form a nitride and / or carbide base material. Can be formed on. Furthermore, if a target having the same metal composition as the target film composition is used, it is easy to obtain a film having a stable composition with less compositional deviation. Further, it is preferable to perform ion plating while applying a bias potential to the substrate, because the adhesion of the film can be further enhanced.

Further, in the present invention, the gas pressure at the time of ion plating is not particularly limited either, but it is 1 × 10 ^{−3 to} 5
It is preferably about 10 ⁻² Torr, and if the gas pressure is set within this range, it is easy to obtain a dense hard coating having high crystallinity and further excellent wear resistance.

Further, the present invention does not limit the method of forming the BN film, and the above-mentioned ion plating method, ion assisted deposition method or the like may be used. When the ion plating method is adopted, a BN film can be formed on the substrate by using a target made of B and reacting the ionized B in an N ₂ atmosphere. When the ion assisted deposition method is adopted, B contained in the crucible is simultaneously irradiated with an electron beam to evaporate B and cause nitrogen ions to react,
BN can be coated on the substrate. At this time, it is preferable to apply a bias potential to the base material because the adhesion of the coating can be further enhanced.

Examples will be described below, but the present invention is not limited to the following examples, and it is within the technical scope of the present invention to make appropriate modifications within the spirit of the preceding and following description.

[0027]

EXAMPLES Example 1 First, a substrate made of platinum foil having a size of 10 mm × 25 mm was mounted on an ion plating apparatus, and the first layer was formed by the following method. After heating the substrate to 400 ° C.,
Of the elements forming the first layer, the cathode having an element other than N as a constituent component is evaporated, and N _{2 is used} as a reaction gas.
A gas was introduced to create an atmosphere of 7 × 10 ⁻³ Torr, and a potential of −150 V was applied to the base material to prepare test pieces coated with 5 μm of the first layer coating of various compositions shown in Table 1. did. The composition of the film was confirmed by inductively coupled argon plasma emission spectrometry and Auger electron spectroscopy.

When laminating the BN film as the second layer, after forming the film of the first layer, the electron beam gun in the above ion plating apparatus was activated, and B was put in the crucible.
B is evaporated by irradiating it with an electron beam, and the degree of vacuum in the device is adjusted to 5 × 10 ⁻⁴ Torr.
By reacting with a nitrogen ion beam at an output of 0 eV and applying a potential of −150 V to the substrate, 3
A BN film having a thickness of μm was formed. The composition of the film was confirmed by electron probe X-ray microanalysis and Auger electron spectroscopy.

An oxidation test under the following conditions was carried out using the test piece thus obtained, and the results shown in Table 1 were obtained. (Conditions for Oxidation Test) Temperature range: room temperature to 1300 ° C. Temperature rising rate: 10 ° / min Atmosphere: Dry air, atmospheric pressure Air flow rate: 150 cc / min

[0030]

[Table 1]

The conventional example (No. 1) in which the BN film is not formed as the second layer and the BN film as the second layer in the film of the conventional example.
Comparing with the example (No. 5) in which the film is formed, it can be seen that the hard film according to the present invention has an oxidation start temperature higher by one step, and thus the oxidation resistance is improved.

No. 2 is (Al, Ti, Si) (C,
This is a comparative example in which the BN film was formed without forming the N) -based film as the first layer. Since the adhesiveness to the base material is poor, the original characteristics of the BN film cannot be exhibited and the oxidation start temperature is low.

No. 3 and 4 are TiN or (Al, T
i) It is a conventional example in which N is used as the first layer and BN is used as the second layer, and it can be seen that the oxidation resistance is inferior to the hard coating according to the present invention.

Example 2 A cemented carbide chip was used as a base material, and the thickness of each film was 10 μm.
A test piece was manufactured in the same manner as in Example 1 except that the thickness was changed to m. The micro Vickers hardness of these coatings is 10
When measured at 0 g, the results shown in Table 1 were obtained. As is apparent from Table 1, comparing the conventional example (No. 1) and the example (No. 5) in which the BN film is formed as the second layer on the coating of the conventional example, respectively, Since the coating has a micro Vickers hardness as high as 1000 or more, it can be seen that the hardness is extremely high.

No. 2 is (Al, Ti, Si) (C,
This is a comparative example in which the BN film was formed without forming the N) -based film as the first layer. Since the adhesiveness to the substrate is poor, the original characteristics of the BN film cannot be exhibited, and the micro Vickers hardness is low. No. 3 and 4 are TiN or (A
It is a conventional example in which l, Ti) N is formed as the first layer and BN is formed as the second layer, and it can be seen that the hardness is lower than that of the hard coating according to the present invention.

Example 3 A two-blade end mill having an outer diameter of 10 mm was manufactured by using cemented carbide as a base material, and the same method as in Example 1 was used except that the base material and the film thickness were formed on the blade surface of each end mill. The hard coating shown in Table 2 was formed. In this case, the film thickness was 4 μm and 2 μm respectively when the first layer and the second layer were formed, and 6 μm when only the first layer or the second layer was formed.

Using the obtained surface-coated end mill, a cutting test was conducted under the following conditions to measure the wear amount of the flank of the end mill cutting edge, and the results shown in Table 2 were obtained. (Cutting conditions) Cutting method: Side cutting down cut Work material: SKD11 (hardness HB219) Depth of cut: Rd 1 mm x Ad 10 mm Cutting speed: 60 m / min Feed: 0.07 mm / tooth (270 mm / m
in) Cutting oil: Air blow Cutting length: 50m

[0038]

[Table 2]

As is clear from Table 2, the hard film-coated end mill (No. 5) according to the present invention has a conventional example (No.
It can be seen that the amount of flank wear is small and the wear resistance is excellent as compared with 1) to 4).

Example 4 A high-speed steel equivalent to JIS SKH51 was used as a base material, and a JIS standard drill having an outer diameter of 10 mm was manufactured. The hard coating shown in Table 3 was formed on the surface of the drill blade.

Using the obtained surface-coated drill, a cutting test was conducted under the following conditions to examine the cutting life.
The results also shown in Table 3 were obtained. (Cutting conditions) Cutting method: Drilling, 5 cuttings each Work material: S55C (hardness HB220) Cutting speed: 30 m / min Feed: 0.2 mm / rev Cutting length: 25 mm (through hole) Cutting oil: Water soluble Emulsion type cutting oil

[0042]

[Table 3]

As is clear from Table 3, the hard coating-coated drill (No. 5) according to the present invention has the conventional examples (No. 1 to No. 1).
It can be seen that compared with 4), the average number of drilled holes is large and the cutting life is long.

Example 5 A mold material corresponding to JIS standard SKD61 was used, and a size of 40 was obtained.
A hard coating shown in Table 4 was formed in the same manner as in Example 4 except that a base material of × 20 × 5 mm was manufactured, and the total coating thickness of the first layer and the second layer was 10 μm. did.

Using the test pieces thus obtained, a heat cycle test was conducted under the following conditions to investigate the durability, and the results shown in Table 4 were obtained together. (Heat cycle test conditions) High temperature bath temperature, holding time: 800 ° C, 150 seconds Low temperature bath temperature, holding time: water cooling, 10 seconds

[0046]

[Table 4]

As is clear from Table 4, the test piece (No. 3) coated with the hard coating according to the present invention is the conventional example (N.
o. Compared with Nos. 1 and 2), the number of cycles leading to cracking was greatly improved, and excellent heat cycle resistance was exhibited.

Example 6 A hard coating shown in Table 5 was formed on the blade surface of each chip by using the same method as in Example 3 except that the type of the base material was different by using the cemented carbide tip as the base material. . Using the obtained surface-coated tip, a cutting test was conducted under the following conditions to measure the wear amount of the flank of the cutting edge of the tip, and the results shown in Table 5 were obtained together. (Cutting conditions) Work material: S45C Cutting speed: 200 m / min Feed rate: 0.3 mm / rev Depth of cut: 2 mm Cutting oil: Dry cutting time: 40 min

[0049]

[Table 5]

As is clear from Table 5, the hard film-coated chip (No. 5) according to the present invention has the conventional examples (No. 1 to No. 1).
It can be seen that the amount of flank wear is small and the wear resistance is excellent as compared with 4).

[0051]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, it is possible to provide a hard coating that exhibits more excellent abrasion resistance while taking advantage of the excellent characteristics of the hard coatings that have been developed so far. It has become possible to provide a hard film-coated member obtained by coating the above-described hard film on a member that requires high wear resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taiji Onishi 179-1 Kanegasaki Nishi-Oike, Uozumi-cho, Akashi-shi, Hyogo Prefecture Akashi Works, Kobe Steel, Ltd. (72) Inventor Yasuaki Sugisaki 1-chome Takatsukadai, Nishi-ku, Kobe-shi, Hyogo No. 5-5 Kobe Steel Co., Ltd., Kobe Research Institute (72) Inventor Masanori Cai 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel Works, Kobe Research Institute

Claims (4)

[Claims] 1. A hard coating formed on the surface of a base material, which has a first layer and a second layer, wherein the first layer is formed on the base material side and comprises (Al _x Ti _1-xy Si _y ) (C _z N _1-z ) where 0.05 ≦ x ≦ 0.75 0.01 ≦ y ≦ 0.1 0 ≦ z ≦ 0.4, and the second layer has the chemical composition A hard coating excellent in wear resistance, which is BN laminated on the surface side. 2. The thickness of the first layer is 0.1 to 20 μm.
The hard coating according to claim 1, which is 3. The thickness of the second layer is 0.1 to 20 μm.
The hard coating according to claim 1 or 2. 4. A hard film-coated member having excellent wear resistance, comprising the hard film according to claim 1 formed on the surface of a base material.