JPH0797679A - Ultra-thin film laminate - Google Patents

Abstract

PURPOSE:To improve the wear resistance and oxidation resistance of the surface of a substrate by alternately repetitively laminating thin films of two kinds of Ti-Al-N compds. varying in compsn. on the surface of the substrate. CONSTITUTION:The thin film 3 which consists of carbides, nitride and carbonitrides of group IVa, Va and VIa metals in periodic table and has a thickness of 0.05 to 5mum is formed by an ion plating method by a vacuum arc discharge on the surface of the hard base material 2, such as cutting tip, drill or end mill, consisting of a WC-base sintered hard a way, cermet, ceramics or high-speed steel, Two kinds of the compds. A, B expressed by TixAl1-xN (where 0<=X<0.5) and TiyAl1-yN (where 0.5<y<=1) are alternately laminated in many layers on the surface of the thin-film layer 3 by setting the sum lambdaof the thickness t1, t2 of these compds. as a repetitive lamination period of 0.5 to 20nm. The thin films 1 having the total thickness of 0.5 to 10mum are thus formed. The wear resistance and oxidation resistance of the substrate 1 are greatly improved by the alternately laminated thin films of the Ti-Al-N alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the surface of a hard base material such as a cutting tool or an abrasion resistant tool, or the surface of an electric / electronic component, a sliding component or a mechanical component in order to improve wear resistance and surface protection function. The present invention relates to an ultrathin film laminate formed in.

[0002]

2. Description of the Related Art Conventionally, in order to improve wear resistance and surface protection function, the surface of a hard base material such as a cutting tool or an abrasion resistant tool made of WC-based cemented carbide, cermet, ceramics, high speed steel, etc. , As a hard coating layer, PVD method or C
The VD method is used to form a single layer or multiple layers of Ti, Hf, Zr carbides, nitrides, carbonitrides, or Al oxides.

Further, for the purpose of improving the oxidation resistance of the hard coating layer, for example, as disclosed in Japanese Patent Publication No. 4-53642, Al is added to the carbon / nitride of Ti described above as the hard coating layer of the cutting tool. It is known to form a solid solution of Ti and Al to form a complex carbide solid solution, a complex nitride solid solution, and a complex carbonitride solid solution, respectively.

Further, in the Journal of the Japan Institute of Metals, Vol. 57, No. 8 (1993) 919-925, in a Ti-Al-N-based hard coating layer, the oxidation resistance is increased as the solid solubility of Al-N increases. Improves, but the solid solubility of Al-N is 75 mol%
It is reported that the hardness decreases when the value exceeds 1.0.

However, in any of the above-mentioned conventional hard coating layers, the characteristics peculiar to the material constituting the coating layer determine the characteristics of the entire coating layer as they are, and they are used for cutting tools such as end mills and throw-away inserts and wear resistant tools. In this case, it is difficult to achieve both wear resistance and oxidation resistance, and especially in high-speed cutting and cutting applications of high hardness materials, if a coating layer material that emphasizes oxidation resistance is adopted, there is a problem that wear resistance decreases. .

On the other hand, as a means for achieving high hardening of the coating layer, there is also a method of laminating nm-thin films and increasing the hardness by the effect of lattice strain energy at the interface. Instead, it sacrifices other properties required for cutting tools and wear resistant tools, and has the disadvantage of being particularly ineffective in terms of oxidation resistance.

In addition to the above cutting tools and abrasion resistant tools, conventionally, wear resistant films and protective films have been formed on the surfaces of electric and electronic parts, sliding parts and machine parts. For example, magnetic tapes, floppy disks or magnetic disks. Such as Co-Ni, Co-P, γ as a wear resistant film on the surface of the high density recording medium.
—Fe ₂ O ₃ is coated, or as a protective film, an oxide such as silicon dioxide, silicon nitride, and aluminum oxide, a nitride, a carbon film or the like having a thickness of about 80 nm is coated.

However, with the progress of high-density and large-capacity recording in recent years, the protective film is required to be further thinned, and the film thickness is required to be 50 nm or less. If the conventional protective film is thinned to 50 nm or less, the abrasion resistance and the corrosion resistance become insufficient, and there is a problem that the above requirements cannot be sufficiently met.

Therefore, the present invention solves the above problems,
An ultra-thin film laminate that achieves improved wear resistance of the hard coating layer in cutting tools and wear-resistant tools, and also has excellent properties as a wear-resistant film and protective film on the surfaces of electrical / electronic parts, sliding parts, and mechanical parts. Is intended to provide.

[0010]

In order to solve the above-mentioned problems, the present invention provides Ti _x Al _1-x N and Ti _y Al _1-y N (0≤x <
Two kinds of compounds of 0.5 and 0.5 <y ≦ 1) are alternately and repeatedly laminated, and a structure in which the entire composition of the laminated body is stoichiometrically aluminum rich is adopted. .

The ultrathin film laminate of the present invention has a repeating stacking period of 0.5 nm to 20 nm and a total film thickness of 0.
The most preferable effect can be obtained by adjusting the thickness to 5 μm to 10 μm, and when used as a coating layer for a cutting tip, a drill or an end mill, the above ultra thin film laminate is
Coating on the surface of hard base materials such as base cemented carbide, cermet, ceramics, high speed steel.

Here, the term “repeated stacking period” means, for example, when two kinds of compounds A and B are alternately stacked repeatedly as shown in FIG. 1, the thickness (t ₁ ) of the compound A and the compound B are
(T ₁ + t ₂ = λ) with the thickness (t ₂ ).

In FIG. 1, reference numeral 1 is an ultrathin film laminate, and 2 is a base material.

When the surface of the base material is coated with the ultrathin film laminate, an interface layer 3 is provided between the ultrathin film laminate 1 and the base material 2 as shown in FIG. Table IVa
1 selected from the group of metal elements belonging to group III, group Va, group VIa
A film thickness of 0.05 μm consisting of at least one kind of compound consisting of a combination of one or more elements and one or more kinds of C and N
It is preferably 5 μm.

In addition, the application of the ultra-thin film laminate is
When it is used as a wear resistant film or a protective film on the surface of electronic parts, sliding parts, and mechanical parts, the total film thickness of electrical and electronic parts is 5 nm.
.About.2 .mu.m, and in the case of sliding parts and mechanical parts, the total film thickness is preferably 0.1 .mu.m to 10 .mu.m.

As a method for forming the above ultra-thin film laminate, there are a CVD method and a PVD method. Particularly, the PVD method can form a ceramic film having a remarkably high melting point and hardness at a temperature of 500 ° C. or lower. Therefore, it can be said to be a preferable production method in that the strength of the substrate can be easily maintained and the influence of atomic diffusion in the interface layer between the laminates can be reduced.

[0017]

The ultrathin film laminate of the present invention uses two kinds of compounds composed of Ti, Al and N to stoichiometrically enrich the aluminum Ti _x Al _1-x N (0 ≦ x
<0.5), and stoichiometrically titanium-rich Ti _y
Al _1-y N (0.5 <y ≦ 1) is alternately and repeatedly laminated to form an aluminum-rich Ti—Al—N compound having excellent oxidation resistance as the composition of the entire thin film.

As described above, the stoichiometrically titanium-containing ultra-thin film layer is included, so that the decrease in hardness that occurs in a single thin film of an aluminum-rich Ti-Al-N compound is suppressed. Both high hardness and oxidation resistance can be achieved. By utilizing this characteristic, when used as a coating layer for a cutting tool or an abrasion resistant tool, the wear life of the tool can be significantly extended.

Further, two different kinds of compounds are alternately mixed with each other to 0.
When laminated with an extremely thin film thickness of 5 nm to 20 nm, the Vickers hardness is 3500 kgf / mm at a load of 25 gf.
High hardness, which cannot be obtained with a thin film of a compound of ² or more, can be realized, and excellent wear resistance is exhibited.

This is because when the repeating stacking period is set to 20 nm or less, the number of atoms forming the interface, that is, atoms in contact with the interface becomes large among the atoms constituting the crystal, which is caused by the interface rather than the characteristic peculiar to the substance. It is considered that the characteristics become remarkable, and the hardness increase appears due to the effect of the lattice strain energy at the interface. On the other hand, the repeated stacking cycle is 0.5
When the thickness is less than or equal to nm, a mixed layer of stacked materials is formed due to the influence of mutual diffusion at the interface, and conversely, when the repeated stacking period is greater than or equal to 20 nm, individual thin film characteristics are dominant. However, in both cases, it is not possible to obtain a remarkable effect of increasing the hardness due to the lamination.

In the ultrathin film laminate of the present invention, it is possible to improve the adhesion strength of the ultrathin film laminate to the substrate by interposing the interface layer between the two, rather than directly forming it on the substrate surface. . This is because by providing an interface layer having intermediate properties between the base material and the ultra-thin film laminate, which have greatly different properties, the changes in properties become continuous and the effect of reducing residual stress in the film is achieved. Can be expected. As for the effect of this interface layer, when the film thickness is less than 0.05 μm, the adhesion strength is not improved, and conversely, when it exceeds 5 μm, the adhesion strength is not further improved. Can be demonstrated.

The same effect as that described above can be obtained by using Ti
-Nitride of Al alloy other than Al type, for example (AlZr)
It can also be obtained by stacking coating films having different alloy compositions such as N, (AlNb) N and (AlHf) N.
According to the present invention, T has a good balance between oxidation resistance and hardness.
i-Al nitride is adopted.

[0023]

EXAMPLES Next, examples carried out to see the effects of the present invention will be described. When forming an ultrathin film laminate in each of the following examples, the nm-order lamination period is measured by observation with a transmission electron microscope (TEM) and a small-angle X-ray analysis method. Further, regarding the long-period stacking structure, the stacking period can be measured by a high-resolution scanning electron microscope.

<Example 1> As a base material, a plurality of cemented carbide cutting tips having a composition of JIS standard P30 and a shape of JISSNG432 were prepared, and the surfaces thereof were subjected to an ion plating method by vacuum arc discharge to obtain a table 1 The ultrathin film laminated structure shown in was formed. Here, the cutting tip samples of the examples of the present invention were No. 1 to No. 26.

[0025]

[Table 1]

FIG. 3 shows a method of manufacturing a cutting tip sample. The sample is formed by forming a plurality of T inside the film forming apparatus 4.
The targets 5 and 6 of the i-Al compound are arranged, the cutting tip 8 is attached to the base material holder 7 that rotates between these targets around the center point of the target, and the rotation speed of the cutting tip and the vacuum arc The repeated stacking cycle was adjusted by adjusting one or both of the discharge current (evaporation amount of the target material).

First, the degree of vacuum in the film forming apparatus 4 is set to 1
The pressure was set to 0 ^-5 Torr, Ar gas was introduced into this atmosphere, the temperature was raised to 500 ° C. while maintaining a vacuum degree of 10 ^-2 Torr, and the cutting tip 8 was cleaned by applying a voltage of -1000 V. Ar gas was exhausted. Next, the film forming apparatus 4
200 cc / m by controlling the time of one or several of N ₂ gas and CH ₄ gas according to the rotation of the substrate.
It is introduced at a ratio of in, and vacuum arc discharge is performed in this state to evaporate and ionize the metal elements of the IVa group, Va group, and VIa group of the periodic table, and the targets 5 and 6 of the Ti—Al compound. When the rotating cutting tip passed in front of the target, a compound layer of the target material and C and N in the introduced gas was formed on the cutting tip.

Further, for comparison with the samples of the above-mentioned examples, hard coated cutting chips having conventional structures shown in Tables 1 to 27 were prepared. In this case, samples 27-29
Is an ion plating method using a vacuum arc discharge using an ordinary film forming apparatus, and the sample 30 is an ordinary CVD method, and a single hard coating is applied to the surface of a cutting tip having the same composition and shape as described above. It was manufactured by forming layers.

In this example, various cutting tip samples prepared as described above were subjected to a continuous cutting test and an intermittent cutting test under the conditions shown in Table 2 below to measure the flank wear width of the cutting edge. The results of each cutting test are shown in Table 3.

[0030]

[Table 2]

[0031]

[Table 3]

From the results shown in Table 3, among the samples having the conventional structure, the samples 27 to 29 in which the hard coating layer was formed by the PVD method were inferior in wear resistance, and the sample 30 formed by the CVD method was inferior in the toughness of the base material. The chipping resistance of was decreased. On the other hand, Samples 1 to 24 (excluding Sample 8) according to the present invention have excellent wear resistance in both continuous cutting and intermittent cutting,
Further, the toughness of the base material was maintained and excellent fracture resistance was exhibited.

Further, from the results of Samples 1 to 7, the optimum stacking cycle of 0.5 nm to 20 nm when the ultrathin film stack is applied to a cutting tool is 0.5 nm to 20 nm. From the test results, it is clear that the film thickness of the interface layer is preferably 0.05 μm to 5 μm.

In addition, from the test results of Samples 9 to 12, the total film thickness of the ultrathin film laminate was 0.5 μm to 10 μm.
It turns out that is suitable.

Further, from the test results of Samples 19 to 26, the structure of the ultrathin film laminate has a composition of aluminum rich Ti _x Al _1-x N in the range of 0 ≦ x <0.5 and 0.5.
Titanium-rich Ti _y Al _1-y N in the range of <y ≦ 1
It can be said that it is appropriate to repeatedly and repeatedly stack the above compounds with each other to form an aluminum-rich Ti-Al-N compound as the whole thin film.

<Example 2> In order to confirm the wear resistance when the ultrathin film laminate is applied to a wear resistant film or a protective film of electric / electronic parts, the surface of the magnetic head is coated with the ultrathin film laminated product,
A contact wear test of the magnetic head with the magnetic disk was conducted.

In this abrasion test, a sintered body made of aluminum and titanium carbide (Vickers hardness of 4000 kgf / mm ² ) was used as a magnetic head, and this was pressed against the protective film on the surface of the magnetic disk with a load of 600 kgf / mm ² , To
A CSS test was conducted in which the magnetic disk was rotated at high speed until the magnetic head floated, the rotation was stopped after flying, and the magnetic head was brought into contact with the disk surface again. Here, the CSS test is a cycle test in which the magnetic head and the magnetic recording medium are set in contact with each other, the magnetic recording medium is rotatably levitated, the rotation is stopped, and the magnetic head and the magnetic recording medium are again brought into contact with each other. Is.

Table 4 shows the results when 100,000 repeated tests were carried out by the CSS test method.

[0039]

[Table 4]

In Table 4, Samples 1 to 14 are examples using the ultrathin film laminate according to the present invention and were prepared by the sputtering method. Sample 15 is a comparative example, and uses SiO ₂ as a protective film.

The hardness of the coating layer cannot be measured because the layer is very thin, and the Ar ion beam (accelerating voltage 3
Since there is an empirical positive correlation between the etching rate of the layer by KV) and the hardness, the etching rate is shown as an alternative value for the hardness.

From the results of Table 4, 0 ≦ x <0.5, 0.5
<Y ≦ 1 and the repeating stacking period is 0.5 n
Regarding Samples 2 to 5 in the range of m to 20 nm, no change was observed in the surface state and the reproduction output, and it was shown that the samples 2 to 5 have excellent wear resistance as compared with other samples, especially Sample 15 of the conventional structure. .

[0043]

As described above, since the ultrathin film laminate of the present invention can have both high hardness and oxidation resistance at the same time,
By using it as a coating layer for cutting tools and abrasion resistant tools, it is possible to have better wear resistance than before while maintaining the strength of the base material, and in particular the cutting life is greatly extended in high speed cutting and cutting applications of high hardness materials. Can be made.

In addition to the above-mentioned applications such as cutting tools, the ultra-thin film laminate of the present invention has a wear-resistant film and protection excellent in wear resistance on the surfaces of electric / electronic parts, sliding parts and machine parts. It can be applied as a membrane.

Further, by using this ultrathin film laminate, it is possible to provide a surface protective film for a magneto-optical recording medium, an optical lens or the like, or a thin film excellent in optical characteristics, electric characteristics and the like.

[Brief description of drawings]

FIG. 1A is a schematic view showing a state in which a base material is coated with an ultrathin film laminate according to the present invention, and FIG. 1B is a partially enlarged view thereof.

FIG. 2 is a schematic diagram showing a state in which a base material is coated with an ultrathin film laminate according to the present invention via an interface layer.

FIG. 3 is a diagram showing a method for forming an ultrathin film laminate according to the present invention.

[Explanation of symbols]

 1 Ultra Thin Film Laminate 2 Base Material 3 Interface Layer 4 Film Forming Device 5, 6 Target 7 Base Material Holder 8 Cutting Tip

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C22C 29/16 C23C 16/34 28/04 (72) Inventor Tsuyoshi Yoshioka 1-1 Kunyokita, Itami City No. 1 Sumitomo Electric Industries Itami Works Co., Ltd. (72) Inventor Kazuo Yamagata 1-1-1 Kunyo Kita, Itami City Sumitomo Electric Works Itami Works

Claims (6)

[Claims] 1. Ti _x Al _1-x N and Ti _y Al _1-y N (0 ≦ x <, composed of Ti, Al and N.
An ultrathin film laminate in which two kinds of compounds of 0.5 and 0.5 <y ≦ 1) are alternately and repeatedly laminated so that the overall composition of the laminate becomes stoichiometrically aluminum-rich. 2. The ultrathin film laminate according to claim 1, wherein the repeating lamination cycle is 0.5 nm to 20 nm,
An ultra-thin film laminate having a total film thickness of 0.5 μm to 10 μm. 3. The surface of a hard base material such as WC-based cemented carbide, cermet, ceramics, high-speed steel, etc., coated with the ultrathin film laminate according to claim 1 or 2, and used as a cutting tip, a drill or an end mill. The coating of the ultrathin film laminate used. 4. The surface of a substrate is coated with the ultrathin film laminate according to claim 1 or 2, and the IVa group, the Va group and the VIa group of the periodic table are provided between the ultrathin film laminate and the substrate. Ultrathin film provided with an interface layer having a film thickness of 0.05 μm to 5 μm, which is made of at least one kind of compound consisting of a combination of one or more kinds of elements selected from the group of the metallic elements described above and one or more kinds of C and N. Laminated coating. 5. The ultrathin film laminate according to claim 1 or 2, wherein the Vickers hardness used as a wear-resistant film or a protective film for electric / electronic parts, sliding parts, mechanical parts is a load of 2.
An ultra-thin film laminate having a weight of 3500 kgf / mm ² or more at 5 gf. 6. The ultrathin film laminate according to claim 5, wherein the total film thickness of the laminate is 5 nm to 10 μm.