JP2000326106A - Hard coating covered tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coating covered tool capable of dealing with dry cutting work and high speed cutting work by increasing oxidation resistance without sacrificing wear resistance and adhesion of a conventional TiAlN coating. SOLUTION: One or more layers (a) and one or more layers (b) are layed alternately, respectively. The layer (a) is composed of metal component: 10-60 atomic % of one or two kinds or more of Si, Cr, Nb and the rest: any one of nitride, carbonitride, nitroxide and carbonitroxide composed of Ti, and has a thickness of 0.1 μm-3 μm. The layer (b) is composed of metal component: 40-75 atomic % of Al and the rest: any one of nitride, carbonitride, nitroxide and carbonitroxide composed of Ti. A layer (c) is laid just one just on a surface of a base material while the layer (b) is laid just on the layer (c). The layer (c) is mainly composed of Ti as its metal component and has a thickness of 0.1 μm-1 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard film-coated tool used for cutting metal materials and the like.

[0002]

2. Description of the Related Art Conventionally, cutting tools coated with TiN, TiCN and the like have been widely used. Since TiN has relatively excellent oxidation resistance, it not only exhibits excellent wear resistance against tool rake surface wear caused by heat generated during cutting, but also has good adhesion to the base material. It is.
Moreover, since TiCN has a higher hardness than TiN, it exhibits excellent characteristics with respect to flank wear of a tool. However, in response to the tendency to increase the cutting speed for the purpose of increasing the efficiency of metal working, the hard coating does not exhibit sufficient oxidation resistance and wear resistance. From such a background, studies have been made to further improve the oxidation resistance and abrasion resistance of the coating. As a result, JP-A-62-56565 and JP-A-2-19415 have been studied.
No. 9 has been developed and applied to cutting tools.

[0003]

The TiAlN film has a Vickers hardness of approximately 2300 to 2800, although it varies depending on the component ratio of Ti and Al contained in the film. Since it is superior to TiN and TiCN, it greatly improves the performance of the cutting tool under cutting conditions in which the cutting edge reaches a high temperature. However, in recent years, in addition to the tendency for the cutting speed to be further increased, dry cutting is regarded as important in terms of environmental issues, and the use environment of cutting tools is becoming increasingly severe.

According to the study of the present inventors, the oxidation start temperature of a TiAlN film in the atmosphere is 450 ° C. of TiN.
On the other hand, the temperature increases to 750 to 900 ° C. depending on the amount of Al added. However, in the above-mentioned dry high-speed cutting, the cutting edge temperature of a tool to be used reaches a high temperature of 900 ° C. or more, and therefore, at present, a sufficient tool life cannot be obtained with the TiAlN film.

The present invention has been made in view of these circumstances, and further improves the oxidation resistance without sacrificing the abrasion resistance and adhesion of the conventional TiAlN film, and achieves dry processing and high-speed cutting. It is an object of the present invention to provide a hard film-coated tool corresponding to the above.

[0006]

Means for Solving the Problems The inventors conducted detailed studies on the effects of various elements on the oxidation resistance, abrasion resistance, and adhesion to a base material of a hard coating and the layer structure of the coating. As a result, a nitride, a carbonitride, an oxynitride, or an oxycarbonitride (hereinafter, referred to as Ti-based nitride, etc.) mainly containing Ti containing one or more of Si, Cr, and Nb in an appropriate amount. ) And metal components contained in nitrides, carbonitrides, oxynitrides, or oxycarbonitrides (hereinafter, referred to as TiAl-based nitrides) containing Ti and Al as main components are limited to specific values. The coatings are alternately coated one or more times,
The present inventors have found that the performance of a cutting tool becomes extremely good in dry high-speed cutting by coating a nitride layer mainly composed of Ti as a metal component directly on the surface of a base material, and reached the present invention.

That is, the present invention relates to high-speed steel, cemented carbide,
Either cermet or ceramic as a base material, one or two of Si, Cr and Nb in atomic% of metal component only
A nitride or carbonitride, oxynitride, or oxycarbonitride composed of at least 10% and at most 60% of the remaining Ti
An a layer having a layer thickness of 0.1 μm or more and 3 μm or less;
A layer b, which is any one of nitride, carbonitride, oxynitride, and oxycarbonitride, composed of i, is alternately coated one or more times, and Ti is a metal component immediately above the base material surface. C with a layer thickness of 0.1 μm or more and 1 μm or less
There is a hard coating coating tool characterized by having a layer and a b layer immediately above the c layer, and the hard coating is desirably coated by physical vapor deposition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First, the constituent requirements of the layer a described in the claims will be described in detail. Generally Ti
When an oxidation test is performed on the AlN film in the air, Al near the surface of the film diffuses outward to the outermost surface, where an alumina layer is formed. According to the study of the present inventors, this is considered to be the reason for improving the oxidation resistance. At this time, a very porous Ti oxide containing no Al is formed immediately below the alumina layer. In the static oxidation test, the alumina layer formed on the outermost surface functions as an oxidation protective film against the inward diffusion of oxygen, which is the progress of oxidation. The layer is easily peeled off from the porous Ti oxide layer immediately below, and does not exert a sufficient effect on the progress of oxidation.

However, by adding one or more of Si, Cr, and Nb to Ti-based nitride or the like in an appropriate amount, not only the oxidation resistance of the film itself is extremely improved, but also the outermost surface has An extremely dense composite oxide layer containing Si, Cr, and Nb serving as an oxidation protection film is formed.
Immediately below it, a porous T which causes the oxidation protective film to peel off
It was confirmed that no i-oxide was formed. To obtain the above effect, one or more of Si, Cr and Nb are
At least 10% of the metal component of the coating must be contained in atomic%. Conversely, if the content exceeds 60%, the ductility or the hardness of the coating is remarkably reduced, and it is difficult to use it as a cutting tool. I can't stand it.

The layer a of the present invention has a thickness limited to 0.1 μm or more and 3 μm or less. When the thickness of the a-layer is less than 0.1 μm, the above-described effect of improving the oxidation resistance is not remarkably exhibited because the thickness of the a-layer is insufficient for inward diffusion of oxygen. Also,
If the thickness of the layer a exceeds 3 μm, the layer a is broken or peeled off during cutting. Therefore, the layer thickness of the layer a is 0.1 μm
At least 3 μm or less. Desirably 0.3 μm or more and 2 μm
m or less.

Although the a-layer has extremely excellent oxidation resistance under static and dynamic conditions, it has a toughness of T
It is not enough compared with i-N-based, Ti-Al-N-based coatings and the like. Therefore, the performance of the tool is not remarkably improved by the single coating of the a layer. Therefore, in order to optimize the balance of wear resistance, oxidation resistance, toughness, and the like, it is necessary to cover the b layer described in claims, which is made of TiAl-based nitride or the like.
The role of Al in the b layer, which is a film of a TiAl-based nitride or the like, is to improve the wear resistance and oxidation resistance of the film. The abrasion and oxidation resistance of the coating improves with increasing Al content in the coating. However, 7
If the content exceeds 5%, the hardness of the film decreases, and the wear resistance required for a tool cannot be obtained. Therefore, in order to obtain a good balance between the wear resistance and the oxidation resistance, the Al content in the b layer is set to 40% by atomic% of only the metal component of the coating.
It is important to adjust to over 75%.

[0012] Neither the a layer nor the b layer is sufficient in adhesion to the base material. Therefore, just above the surface of the base material, a layer c of a nitride mainly composed of Ti as a metal component having excellent adhesion to the b layer and the base material and having appropriate wear resistance and oxidation resistance is required. is there. The c-layer is preferably made of TiN having a lower hardness than the a-layer and the b-layer. However, TiN is made of a metal belonging to the group IVa, Va, or VIa of the periodic table and Al, S
When a small amount of i, Y, Co, or the like is contained, the same effect can be obtained even when the content is less than 10 at% in atomic% of the metal component alone.

The thickness of the layer c is limited to 0.1 μm or more and 1 μm or less. The greater the thickness of the layer c, the more noticeable the improvement in adhesion. However, in general, during cutting, the coating at the cutting edge wears in the form of an oblique cross section, and therefore oxidation proceeds preferentially over the c layer, which has lower oxidation resistance than the a layer and the b layer. Therefore, when the thickness of the c layer is large, that is, when the exposed area of the c layer due to abrasion during cutting is large, preferential oxidation of the c layer becomes remarkable, and the performance of the cutting tool is not significantly improved. Further, when the thickness of the layer c is extremely thin, the effect of improving the adhesion is not remarkably exhibited. For the reasons described above, the layer thickness of the c layer is set to 0.1 μm or more and 1 μm or less. Preferably, 0.
It is 2 μm or more and 0.4 μm or less.

As described above, in the present invention, the layer c having excellent adhesion to the base material is coated directly on the surface of the base material, and the wear resistance and oxidation resistance of the film itself are well-balanced thereon. It is extremely important to coat the layer and the layer a, which has remarkably excellent oxidation resistance, and as a result, it becomes possible to obtain a cutting tool corresponding to dry high-speed cutting. A similar effect can be obtained by a multilayer coating in which a layer c is coated immediately above the base material surface, a layer b is coated thereon, and then an a layer and a b layer are alternately laminated.

Each of the layers a and b can be adjusted to any of nitride, carbonitride, oxynitride and oxycarbonitride, if necessary, and the same effect can be obtained with tools coated with them. can get.

The method of coating the hard film-coated tool of the present invention is not particularly limited, but in consideration of the thermal effect on the coated base material, the fatigue strength of the tool, the adhesion of the film, etc. Arc discharge ion plating that can be coated at a relatively low temperature and compressive stress remains in the coated film,
Alternatively, a physical vapor deposition method of applying a bias voltage to the coating base material side such as sputtering is preferable. Hereinafter, the present invention will be described based on examples.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Using a small arc ion plating apparatus, various alloy targets as sources of metal components, N ₂ gas, CH ₄ gas, and Ar / O ₂ as reaction gases were used.
From the mixed gas, a material capable of obtaining a target film is selected, and under the conditions of a coated substrate temperature of 400 ° C. and a reaction gas pressure of 3.0 Pa, a cemented carbide 6-flute end mill (outer diameter 8 mm) as a coated substrate and -1 for cemented carbide drill (outer diameter 8mm)
A film was formed by applying a potential of 50 V so that the total film thickness was 4 μm.

Using the obtained hard film-coated end mill and drill, processing is performed under the following cutting conditions until the tool cannot be cut due to chipping or wear of the cutting edge.
The cutting length and the number of drillings at that time were defined as the tool life. Table 1 shows the details of the hard coatings according to the present invention and comparative examples and the cutting results thereof. Table 2 also shows cutting results of the conventional example.

End mill cutting conditions are as follows: a 6-blade cemented carbide end mill is used as a tool, the outer diameter is 8 mm, the side cutting is down cutting, and the work material is SKD11 (HRC6).
0), cutting amount Ad = 12 mm, Rd = 0.2 mm,
Cutting speed = 200m / min, feed amount 0.03mm / t
ooth, cutting oil = none, but using air blow.

Next, the cutting conditions of the drill were as follows: a cemented carbide drill was used as a tool, and an outer diameter of 8 mm was used.
40 (HRC30) drilling, cutting speed = 90m / m
in, feed rate = 0.2 mm / rev, cutting oil = none, but using an air blow to machine a blind hole with a hole depth of 24 mm. In addition, the number of machined holes ended at a maximum of 2000 holes.

[0021]

[Table 1]

[0022]

[Table 2]

As can be seen from Tables 1 and 2, the tool life of the example of the present invention is remarkably stable as compared with the comparative example and the conventional example, and particularly, by providing the c layer at 0.2 to 0.4 μm. The drill test can stably process more than 2000 holes. In addition, it can be seen that the end mill is sufficient for dry high-speed cutting. Next, in Comparative Example 27, both the coating composition and the thickness of the a-layer and the b-layer are included in the present invention. Peeling occurred, resulting in a very short life. In Comparative Example 35, although the tool life was the best among Comparative Examples, c
Since the layer thickness is large, the tool life is shorter than the tool life of the example of the present invention.

[0024]

As described above, the hard-coated tool of the present invention has superior oxidation resistance and wear resistance as compared with the conventional coated tool, so that the tool life in dry high-speed cutting is significantly longer. It is extremely effective not only for improving productivity in cutting but also for addressing environmental issues.

Claims (2)

[Claims] 1. A high-speed steel, a cemented carbide, a cermet, or a ceramic as a base material, and an atomic% of only a metal component.
And one or more of Si, Cr and Nb are 10%
Not less than 60% and any of nitride, carbonitride, oxynitride and oxycarbonitride composed of residual Ti, having a layer thickness of 0.1
a layer of not less than 3 μm and not more than 3 μm, and the atomic% of the metal component alone is more than 40% Al and not more than 75%, and the rest: nitride, carbonitride, oxynitride, oxycarbonitride composed of Ti Any one of the b layers is alternately coated with one or more layers,
A hard film coating characterized by a c layer having a thickness of 0.1 μm or more and 1 μm or less made of a nitride mainly composed of Ti as a metal component right above the surface of the base material, and a b layer immediately above the c layer. tool. 2. A tool for coating a hard coating, wherein the hard coating according to claim 1 is coated by a physical vapor deposition method.