JPH10128602A - Coated cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve wear resistance by forming a double compound solid solution layer composed of a nitride or an oxinitride of Ti and an oxide or an oxinitride of Al outside of a layer composed of TiN, Ti nitride of TiC or TiCN, carbide or carbonitride. SOLUTION: A multilayer hard film is formed as a base material of a cutting tool made of ceramics by CVD method. Film formation is TiN+TiAlN+(Ti, Al) (N, O)+TiN+TiAlN+(Ti, Al) (N, O)+TiC, that is, TiC film is formed on two layers of TiN+TiAlN+(Ti, Al) (N, O), to have a film thickness of about 3.5μm. TiAlN layer is interposed between both layers. Thus, the film formation condition of (Ti, Al) (N, O) is made favorable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool, such as a milling tool, made of a silicon nitride material, and more particularly to a hard coating excellent in wear resistance on the surface of a silicon nitride base material. The present invention relates to a coated cutting tool having a film formed thereon.

[0002]

2. Description of the Related Art A cutting tool, such as a cermet tool or a cemented carbide tool, has a hard coating film made of a nitride or carbide such as Ti on the surface of a tool base material for improving wear resistance. Something is going on.

[0003] As the method, in addition to the CVD method (chemical vapor deposition method) and the PVD method (physical vapor deposition method), TiN, TiAl is used by an ion plating method or a sputtering method.
Coatings such as N, TiAlC or TiAlCN have been performed.

Japanese Patent Publication No. 4-53642 discloses an invention related to such a coated cutting tool.
On the surface of the base member composed of iCN-based cermet,
(Ti, Al) C, (Ti, Al) N, and (Ti,
Al) A hard coating layer consisting of one single layer or two or more coatings of CN is formed by a CVD method, a PVD method, or the like.
The surface-coated tool had excellent wear resistance and was deposited with an average layer thickness of 0.5 to 10 μm.

As a cutting tool, a ceramic tool exhibits excellent performance in high-speed and high-efficiency machining of general steel and high-hardness materials due to its excellent high-temperature characteristics and chemical stability. In particular, it has excellent wear resistance and crater resistance, making it possible to perform ultra-high-speed cutting, and has a very low affinity with the work material, so it maintains a stable finished surface for a long time. I have.

[0006] Among them, silicon nitride ceramics are tough and have excellent fracture resistance, so they are used for high-speed rough machining (V = 250 m / min or more) of cast iron, heat-resistant alloys, and the like.
Both wet processing and dry processing were possible.

[0007] Such a ceramic tool is usually used without forming a hard coating on the surface.

[0008]

However, in recent years, there has been a demand for higher cutting speeds, and cutting conditions tend to be more severe. Therefore, wear resistance has been further improved than conventional cutting tools. Cutting tools have been desired, and this is no exception for silicon nitride tools. .

[0009]

Accordingly, the present inventors have made intensive studies to improve the wear resistance of the conventional coated cemented carbide from the above-mentioned viewpoints. It has been found that by changing the solid solution layer, the wear resistance can be significantly improved. That is, Ti,
The composite compound solid solution layer of Al is made of a nitride or oxynitride of Ti and an oxide or oxynitride of Al, and a Ti compound is dispersed and dissolved in Al ₂ O ₃ or Al ₂ O ₃ N. Thus, in addition to oxidation resistance, excellent fracture resistance and abrasion resistance are obtained, and the TN, TiC or TiCN of TiN having this composite compound solid solution layer formed on the base metal surface
By forming the i layer outside the first layer made of nitride, carbide or carbonitride, the wear resistance is remarkably improved.

[0010] In addition to such a configuration, the above T
By interposing an aluminum compound between the i and Al composite compound solid solution layer and the first layer, this effect can be further promoted. As an aluminum compound, aluminum oxide is particularly effective for improving wear resistance. is there.

The present invention has been made on the basis of the above research results, and includes a first layer made of a nitride, carbide or carbonitride of Ti and a first layer made of an aluminum compound on a surface of a silicon nitride base material. A hard layer in which two layers, a third layer of a compound nitride solid solution layer of Ti nitride or oxynitride and Al oxide or oxynitride [hereinafter referred to as (Ti, Al) (N, O) layer] The present invention is characterized by a coated cutting tool provided with a coating film.

In addition, the above (Ti, Al)
In the (N, O) layer, a large amount of Ti is present on the surface side of the base material, and the amount of Ti decreases toward the outside, and Al is mainly used in the outermost portion. The adhesion between the layer and the underlying Ti compound layer can be increased, and as a result, the fracture resistance can be increased.

It is to be noted that the hard coating film includes the first
Laminating the layer to the third layer two or more times in the same order tends to have higher abrasion resistance than a single layer.

Further, the thickness of the hard coating film is 3.0 to 3.0.
It is preferably in the range of 6.0 μm. That is, if the thickness is less than 3.0 μm, the abrasion resistance and chipping resistance may be low, while if the thickness is more than 6.0 μm, the adhesion of the coating film may be small and the coating may be peeled off.

[0015]

Next, the coated cutting tool of the present invention will be specifically described with reference to examples.

Example 1 A multilayer hard film was formed by a known CVD method using a ceramic cutting tool (hereinafter referred to as a chip) of SN6000 grade made by Kyocera as a base material and having a shape conforming to JIS CNGN120408. Was designated as Example Product 1.
The film configuration was changed to TiN + TiAlN + (Ti, Al) (N,
O) + TiN + TiAlN + (Ti, Al) (N, O)
+ TiC, ie, TiN + TiAlN + (Ti, A
1) A TiC film was formed on two layers of the (N, O) film configuration, and the film thickness was about 3.5 μm.

[0017] was measured main cutting edge V _B worn amount and the main cutting edge V _{B MAX} wear amount by performing a cutting test under the following conditions using the chip.

[0018] As a result, the main cutting edge V _B wear amount at 0.16 mm, the main cutting edge V _{B MAX} wear amount was 0.19 mm.

Comparative Example 1 As in Example 1, the film configuration was changed to TiN + (Ti, Al).
(N, O) + TiN + (Ti, Al) (N, O) + Ti
C, that is, a TiC film was formed on a stack of two layers of TiN + (Ti, Al) (N, O), and a chip having a thickness of about 3.0 μm was manufactured. And The same test as in Example 1 was performed using this comparative example 1.

[0020] As a result, the main cutting edge V _B the amount of wear is 0.22m
m, the wear amount of the main cutting edge V _{B MAX} was 0.33 mm, and the wear amount was larger than that of the product of Example 1 in all cases.

This is because (T) is formed on the TiN layer in this comparative example.
(i, Al) (N, O) layer was directly formed (Ti, A
l) The film formation state of (N, O) is slightly poor, while in the first embodiment, the film formation state of (Ti, Al) (N, O) is reduced by interposing a TiAlN layer between both layers. It is presumed that the reason was good.

Example 2 A multilayer hard film was formed by a known CVD method using a ceramic cutting tool (hereinafter, referred to as a chip) of a SN6000 grade made by Kyocera as a base material and having a shape conforming to JIS CNGN120408. Was designated as Example Product 2.
The film configuration was changed to TiN + Al ₂ O ₃ + (Ti, Al) (N,
O) + TiN + Al ₂ O ₃ + (Ti, Al) (N, O)
+ TiC, ie, TiN + TiAlN + (Ti, A
1) A TiC film was formed on two layers of the (N, O) film configuration, and the film thickness was about 3.5 μm.

[0023] Using this chip was measured main cutting edge V _B worn amount and the main cutting edge V _{B MAX} wear amount by performing a cutting test under the following conditions.

[0024] As a result, the main cutting edge V _B wear amount at 0.10 mm, with the main cutting edge V _{B MAX} wear amount 0.16 mm, was wear amount less than either Example 1.

This is because a TiN layer and (Ti, Al) (N,
This is probably because the layer formed between the O) layers was composed of aluminum oxide with respect to the TiAlN of Example 1.

EXAMPLE 3 The hard coating film of the chip of Example 2 was 2.8 each.
Two types of chips having a size of μm and 6.5 μm were formed, and a processing test was performed under the same conditions as in Example 2.

[0027] As a result, the chip of the coating film thickness 2.8μm is a main cutting edge V _B the amount of wear 0.18 mm, the major cutting edge V
_{The B MAX} wear amount was 0.22 mm, which was larger than Examples 1 and 2.

In the case of a chip having a coating film thickness of 6.5 μm, the coating film sometimes peeled off.

In addition, when the EPMA composition analysis of the hard coating film was carried out for the products of Examples 1, 2, and 3 and the experimental product, the (Ti, Al) (N,
In the O) layer, a large amount of Ti is present on the base material surface side,
Ti further decreases toward the outside, and in the outermost part, Al decreases.
Has been confirmed to be the main configuration.
The reason that the wear resistance of the product of Example 2 was excellent was as follows.
It is conceivable that there is such a gradient distribution of Ti.

It should be noted that the present invention is not limited to the embodiments described above, but may be of any other form without departing from the object of the present invention, such as forming a TiN film on the surface. Needless to say.

[0031]

As described above, according to the present invention, the first layer made of nitride, carbide or carbonitride of Ti, the second layer made of aluminum compound,
Composite compound solid solution layer of nitride or oxynitride of i and oxide or oxynitride of Al [(Ti, Al) (N, O)
), The wear resistance and chipping resistance of the cutting tool were remarkably improved. Therefore, it is economical and can sufficiently cope with a further increase in the cutting speed.

Claims (2)

[Claims] 1. A first layer made of a nitride, carbide or carbonitride of Ti, a second layer made of an aluminum compound, a nitride or an oxynitride of Ti and an oxide of Al on a surface of a silicon nitride base material. Or a third compound solid solution of oxynitride
A coated cutting tool comprising a hard coating film in which layers are sequentially arranged. 2. The coated cutting tool according to claim 1, wherein said second layer is made of aluminum oxide.