JPH1161380A - Wear resistant multi-layer type hard coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-layer hard coating film excellent in adhesion between a coating film and a base material and wear resistance even for a wear resistant multi-layer hard coating film formed to a tool base material surface. SOLUTION: In the wear resistant multi-layer type hard coating film formed to a tool base material surface, coating films made of a chemical composition shown with two kinds of TiAlN of a low hardness and high hardness are alternately laminated, a low hardness TiAlN layer has a chemical composition shown by 0.1<=x<=0.4 in Ti1-x Alx N, a high hardness TiAlN layer has a chemical composition shown by 0.4<=x<=0.75 in Ti1-x Alx N.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasion-resistant multilayer hard film structure useful as a surface coating material for a tool used for machining such as milling, cutting and drilling.

[0002]

2. Description of the Related Art When manufacturing high-speed tool steel, cemented carbide tool steel, or the like, a nitride such as Ti is coated on the surface of a tool base material for the purpose of improving performance such as wear resistance. Formation of an abrasion resistant film made of carbon or carbide has been performed. As a method for forming a wear-resistant film on the surface of a base material, a CVD method (chemical vapor deposition method) and a PVD method (physical vapor deposition method) are conventionally known. However, in the former method, the base material may be deteriorated because the base material is exposed to the high-temperature treatment.
The latter method tends to be preferred for tools for which the properties of the base material are also important. Therefore, a high-frequency discharge plasma CVD method, a reactive ion plating method, a sputtering method, and the like, which can perform a coating treatment under a relatively low temperature condition, have been adopted.

As a wear-resistant film for tools and the like, TiN and TiC by an ion plating method are widely used.
In particular, TiN films excellent in high-temperature oxidation resistance (heat resistance) have been widely put to practical use. That is, since TiN has better heat resistance than TiC, it has a function of protecting the tool rake face, which is heated by processing heat or frictional heat during cutting, from crater wear. However, since TiN has a lower hardness than TiC, it is rather vulnerable to flank wear generated on a flank in contact with a work material, and TiC shows higher durability against flank wear.

[0004] In recent years, there has been a demand for a higher cutting speed, and cutting conditions tend to be more severe. Therefore, the conventional TiN film as described above cannot meet this demand. Therefore, as a film having even better heat resistance and hardness, a film made of TiAlN, TiAlC, or TiAlCN by an ion plating method or a sputtering method has been proposed (JP-A-62-56565).

[0005] Since the above-mentioned PVD method is a low-temperature film method utilizing the energy of ions, there is a gap between the surface of the base material and the film.
There is no diffusion layer due to heat as seen in the CVD method. Therefore, the film formed by the PVD method is CV
Generally, the adhesion is inferior to the film formed by the method D. On the other hand, recently, from the viewpoint of improving the wear resistance and extending the life, there is a tendency to increase the thickness of the coating, but as the thickness increases, the internal stress of the coating increases,
Cracks occur in the film or film adhesion is reduced, which causes film peeling. As described above, (Al, Ti) (N, C) -based coatings have been proposed as high-abrasion-resistant coatings that can replace the TiN coating. However, these coatings are more internal than the TiN coating. Since the stress is more than twice as high, it is put to practical use by forming a film as thin as possible as compared with the case of forming a TiN film. In view of the above, there has been a demand for an improvement in a film forming technique that can sufficiently exhibit particularly excellent properties such as an (Al, Ti) (N, C) -based film.

In view of the above circumstances, it is possible to form a film under relatively low temperature conditions by focusing on such circumstances, and nevertheless, it is excellent in adhesion and film strength, and has excellent resistance to crater wear and flank wear. An abrasion-resistant multilayer hard coating was provided (JP-A-6-136514). This coating configuration TiC _x N _1-x (where, 0 ≦ x ≦ 0.6) and the film layer made of a chemical composition represented _{by, (Al y Ti 1-y} )
(N _z C _1-z ) (provided that 0.56 ≦ y ≦ 0.75, 0.
6 ≦ z ≦ 1), four or more film layers alternately adjacent to each other and having a chemical composition represented by the formula:
It is formed on the surface of the tool base material of 6 to 12 μm.

The abrasion-resistant hard coating described above has not been sufficiently abrasion-resistant for the following reasons. That is, TiN (x =
0) and (Al _y Ti _1-y ) (N _z C _1-z ), the hardness and oxidation resistance of the TiN layer are insufficient, and TiC
_{x N 1-x (0 ≦} x ≦ 0.6) and _{(Al y Ti 1-y)} (N
_z C _1-z) and for higher even hardness better, stacking, and found that it is due to adhesion of the adhesion and the two layers of the base material is insufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a multilayer hard film which is excellent in the adhesion between the film and the substrate and further excellent in abrasion resistance. Is what you do.

[0009]

The invention which has achieved the above object is an abrasion-resistant multilayer hard coating formed on the surface of a tool base material, comprising two types of TiAlN of low hardness and high hardness.
Wherein the low-hardness TiAl is formed by alternately laminating films having the chemical composition represented by the following formula (1).
The N layer is made of Ti _1-x Al _x N and has a chemical composition represented by 0.1 ≦ x ≦ 0.4.
_1-x Al _x N having a chemical composition represented by 0.4 <x ≦ 0.75 (Claim 2);
The substrate bias voltage at the time of coating-1
TiAlN of high hardness formed under the condition of 0-30V
The layer is formed under the condition of a substrate bias voltage of -50 to -150 V (Claim 3), and the number of the unit film layers to be laminated is 10 or more (Claim 4). Further, the thickness ratio between the low hardness layer and the high hardness layer is 5: 1 to 1
It is a wear-resistant multilayer hard coating having a ratio of 1:10 (claim 5).

The present invention relates to a TiAlN having a very high hardness.
By intentionally sandwiching TiAlN, which has low hardness, that is, small internal stress of the coating, into the coating to form a laminated structure, the internal stress of the entire coating is relaxed, and the adhesion between the coating and the substrate is improved. Further, by adopting the laminated structure, the cracks generated in the surface layer of the film can be improved by improving the wear resistance by suppressing the propagation of the cracks by the adjacent film layer as in the prior art. Is composed of the same element as TiAlN, so that the adhesion between the laminated films is very excellent, and the peeling of the film between the layers is reduced.

Incidentally, TiAlN has a higher hardness than TiN, and the hardness generally increases as the Al ratio increases. Therefore, compared to a TiAlN layer usually formed, a lower Al
By setting the composition, a low hardness TiAlN layer is formed.
In order to exhibit the effect of the present invention, the Al composition of the low hardness TiAlN layer should be 0.1 ≤ x ≤ Ti _1-x Al _x N.
0.4, more preferably 0.2 ≦ x ≦ 0.3. If x <0.1, the effect of adding Al cannot be obtained, and if x> 0.4, the hardness becomes too high, and the layer does not function as a low hardness layer.

Next, the TiAlN layer of high hardness is made of Ti _1-x A
It is necessary that l _x N _satisfy 0.4 <x ≦ 0.75, more preferably 0.6 ≦ x ≦ 0.65. When x ≦ 0.4, it does not act as a high hardness layer,
Further, even when x> 0.75, the composition of the coating layer approaches AlN, so that sufficient hardness cannot be obtained. In addition, T is generally formed by ion plating or sputtering.
It is known that the hardness of the iAlN film is greatly affected by the substrate bias voltage at the time of coating, and by controlling the bias voltage, low hardness and high hardness TiAl are obtained.
N layers can be separately formed.

As a condition for forming the low hardness TiAlN layer, the bias voltage (Vb) is suitably −30 V ≦ Vb ≦ −10 V, more preferably −20 V ≦ Vb ≦ −10 V. When Vb <−30 V, it does not act as a low hardness layer. When Vb> −10 V, it approaches the plasma potential of the arc discharge plasma, making it difficult to apply a stable voltage. Further, at 0 V bias, the effect of ion plating is obtained. The properties of the coating deteriorate.

As a condition for forming the high hardness TiAlN layer, it is appropriate that the bias voltage is in a range of -150 V ≦ Vb ≦ −50 V, and more preferably, −100 V ≦ V
It is desirable that b ≦ −50. When Vb> −50 V, the layer no longer functions as a high hardness layer, and when Vb <−150 V, the hardness decreases again, and the layer does not function as a high hardness layer. still,
In this embodiment, the bias voltage is changed discontinuously between the first layer (low hardness layer) and the second layer (high hardness layer).
It is also possible to gradually change the change in the bias voltage between the layer and the second layer at a certain time with a gradient.

[0015] The number of unit film layers to be laminated next is 10 or more, more preferably 20 or more.
If the number is less than 0, good characteristics cannot be obtained. In the present invention, the thickness ratio (thickness ratio) between the low hardness layer and the high hardness layer is 5: 1 to 1:10.
(More preferably 2: 1 to 1: 5). 5: 1
When the ratio of the low hardness layer increases further, the overall hardness decreases and the wear resistance decreases. On the other hand, if the ratio of the high hardness layer exceeds 1:10, the overall hardness becomes too high, and the adhesion of the film decreases.

[0016]

【Example】

<Embodiment 1> At least two arc evaporation sources mounted at positions opposed to each other across a revolving substrate table by a cathodic arc type ion plating apparatus are provided with T
A target having a composition of i _{1- x} Al _x (0.1 ≦ x ≦ 0.4) and a target having a composition of Ti _0.5 Al _0.5 are incorporated,
Coating on a high speed steel end mill (φ10) was performed.

In forming the multilayer hard film of the present invention,
First, the vacuum chamber of the device must be 5 × 10^-FiveTor
After evacuation to below r, the substrate is heated by a heater.
U. Then, in an atmosphere without gas or in an Ar gas atmosphere
Generates an arc discharge at the
Perform sputter cleaning. Ti for cleaning
_1-xAl_x(0.1 ≦ x ≦ 0.4), Ti_0.5Al_0.5
Discharge one or both of the targets simultaneously
good. After cleaning is completed, the inside of the chamber is changed to a nitrogen atmosphere.
And Ti_1-xAl_x(0.1 ≦ x ≦ 0.4), Ti
_0.5Al_0.5Arc discharge is simultaneously opened at both targets
Start. Typical conditions for coating are as follows
is there.

<Coating conditions> Nitrogen gas pressure: 2 to 4 × 10 ⁻² Torr (2 × 10 ⁻² Torr: experimental conditions) Arc current: 80 to 200 A (100 A: experimental conditions) Bias voltage: −40 --150 V (-50 V ... experimental conditions)-Film thickness: 2.5-3.0 m (Examples also vary within this range) While rotating the substrate table under the above gas pressure conditions,
When targets having different compositions are simultaneously discharged, TiA having a composition corresponding to the target composition is provided in front of each target.
As a result, two types of Ti having different compositions are formed.
A multilayer hard film in which AlN films are alternately laminated is formed. The film thickness of each layer can be adjusted by changing the rotation speed of the rotating substrate holder or adjusting the arc current flowing through the target. Further, in order to increase the thickness of each layer to a certain extent or more, two types of targets may be alternately discharged.

A cutting test was performed on the end mill on which various TiAlN films were formed by the above method under the following conditions, and the amount of wear of the cutting edge was measured. <Cutting conditions>-Work material: SKD61 (HRC30)-Cutting speed: 30 m / min-Feeding: 0.07 mm / blade-Cutting depth: 1 mm (radial direction), 15 mm (axial direction)-Cutting method: down cut, air blow Table 1 shows the results of the cutting test together with the layer structure of each film.
For comparison, Table 1 shows a TiAlN single layer and a laminate of a conventional TiN and TiAlN layer.

[0020]

[Table 1]

(Evaluation) Examples of Table 1 (Nos. 1 to 11)
And Comparative Example (Nos. 12 to 15), Comparative Example N
o. In Comparative Example N, the number of layers was smaller than the specific number of the present invention.
o. In Comparative Example No. 13, the film thickness ratio was out of the specific ratio of the present invention. Reference numeral 14 denotes a single layer of a TiAlN film.
Reference numeral 15 denotes a TiN and TiAlN laminated film. When compared with the wear amount (mm) of the cutting edge portion of the example, the comparative example is inferior, and the example has good characteristics. It turns out that.

<Embodiment 2> TiAlN of low hardness and high hardness
Film stacking is also possible by periodically changing the bias voltage during coating. In this case, the thickness of each layer can be adjusted by adjusting the time during which the bias voltage is kept constant or by increasing or decreasing the arc current. Using a target composed of one kind of Ti _0.5 Al _0.5 as a target, a cutting test was performed on the end mill on which various TiAlN films were formed under the same conditions as in Example 1, and the result of measuring the amount of wear of the cutting edge was shown. It is shown in Table 2. TiA as a comparative example
Also shown are a 1N single layer and a stack of prior art TiN and TiAlN layers. (Common with Example 1).

[0023]

[Table 2]

(Evaluation) When the examples (Nos. 1 to 5) in Table 2 are compared with the comparative examples (Nos. 6 to 9), the comparative example Nos. 6,
No. 7, No. The first layer bias voltage is a value outside the range specified in the present invention, and particularly, the first layer bias voltage is the same as that of No. 1 in the present invention. 8 is T
It is a single layer of the iAlN film. 9 is TiN
In comparison with the wear amount of the cutting edge of the example, the comparative example is inferior, and that of the example has good characteristics. Is known.

[0025]

As described above, according to the present invention, a multilayer hard film having excellent adhesion to the substrate and very excellent abrasion resistance was obtained.

Claims (5)

[Claims] 1. A wear-resistant multilayer hard coating formed on the surface of a tool base material, comprising two types of Ti of low hardness and high hardness.
An abrasion-resistant multilayer hard film, wherein films having a chemical composition represented by AlN are alternately stacked adjacent to each other. 2. The method according to claim 1, wherein the low hardness TiAlN layer is Ti _1-x Al _x
N has a chemical composition represented by 0.1 ≦ x ≦ 0.4, and a hard TiAlN layer is formed of Ti _1-x Al _x N at 0.1.
The abrasion-resistant multilayer hard coating according to claim 1, comprising a chemical composition represented by the following formula: 4 <x≤0.75. 3. A low-hardness TiAlN layer is formed under a substrate bias voltage of -10 to -30 V during coating, and a high-hardness TiAlN layer is formed at a substrate bias voltage of -50 V.
The abrasion-resistant multilayer hard coating according to claim 1, which is formed under a condition of -150V. 4. The wear-resistant multilayer hard coating according to claim 1, wherein the number of unit coating layers to be laminated is 10 or more. 5. The low-hardness layer and the high-hardness layer have a thickness ratio of 5: 1 to 1.
The wear-resistant multilayer hard coating according to any one of claims 1 to 3, wherein the ratio is 1:10.