JPH0711459A - Coated cermet alloy - Google Patents

Abstract

PURPOSE:To provide a tool having a long service life by imparting a multilayer structure and a gradient compsn. to the coating film of coated cermet used as a cutting tool material, a wear resistant tool material or a shock resistant tool material. CONSTITUTION:When a coated cermet alloy used for a cutting tool, a wear resistant tool, a shock resistant tool, etc., is produced, coating with a TiN film as the lowest layer is carried out to form a multilayer film in combination with a TiCN film and an intermediate layer having continuously varied concn. of C is interposed in the multilayer film. The objective coated cermet alloy is produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coated cermet alloy for use in cutting tool materials, wear resistant tool materials and impact resistant tool materials.

[0002]

2. Description of the Related Art Generally, a method for forming a hard coating on a cemented carbide or a sintered alloy such as cermet is roughly classified into a chemical vapor deposition method (CVD method) and a physical vapor deposition method (PVD method).
Based on a cermet alloy based on a compound of Ti, P
When the TiCN film is formed by the VD method, it has a higher residual compressive stress than the TiN film, so the adhesion to the cermet alloy is weak, and it can practically be used as a cutting tool, abrasion resistant tool or impact resistant tool. No coated cermet alloy could be obtained.

Further, since the CVD method is performed at a high temperature, K.K. As RTSCH shows (Journal
of Materials Science 22
(1987)), the metallic Ni contained in the cermet alloy and the coating component Ti react with each other to form an intermetallic compound composed of Ti and Ni in the coating, which can withstand use. No coated cermet alloy could be obtained.

[0004]

DISCLOSURE OF THE INVENTION The present invention has solved the above-mentioned problems. Specifically, in the PVD method,
Residual compressive stress is lower than TiCN film, and TiCN
An object of the present invention is to provide a coated cermet alloy coated with a TiCN film that can withstand use by combining with a TiN film that is softer than the film and has excellent adhesion to a substrate.

Further, in the CVD method, by adopting the CVD method at a temperature higher than the temperature at which metallic Ni in the cermet alloy reacts with Ti as a coating component, a pure hard material containing no metallic compound of Ni and Ti in the coating film is used. An object of the present invention is to provide a coated cermet alloy having a TiCN film which realizes the film and can be used.

[0006]

Therefore, the inventors of the present invention have been studying coating a cermet alloy with a TiCN film. As a result, in the PVD method, a TiN film having a residual compressive stress smaller than that of the TiCN film is obtained. It was found that the TiCN film can be easily formed on the cermet alloy by adopting the multi-layer structure.

Therefore, in the coated cermet alloy of the present invention, as the number of layers increases, the thickness of each TiCN film becomes smaller, and the residual compressive stress of the TiCN film is reduced. Is improved,
The residual compressive stress of the TiCN film can be further absorbed and relaxed to reduce the compressive stress of the entire film. Desirably, the lowermost film is the above-mentioned residual compressive stress, and if the hardness is TiN film, the adhesion to the substrate is further improved. To do. Further, the adhesiveness between the multilayer films is further strengthened by interposing an intermediate layer in which the C concentration is continuously changed in the middle, so that peeling of the layers in the film during use,
It consists of being able to further suppress the reduction of destruction.

That is, a compressive stress is formed on the film during coating, but in the case of a cermet alloy, the coefficient of thermal expansion is generally larger than that of a TiN or TiCN film, so that the residual compressive stress of the film increases in the cooling step. Therefore, the residual compressive stress is reduced by slowing the cooling rate or performing heat treatment after coating, and the coated cermet alloy of the present invention exhibits further characteristics.

Further, as the number of layers increases, the hardness of the coating tends to increase and the abrasion resistance tends to improve. This decrease is 1
It appears remarkably in 0 or more layers, and in order to improve wear resistance, 10 or more layers of coating are desirable. In this case, even if the cross-section of the film is observed, no layer is observed and it may appear as a single layer.

Next, in the CVD method, generally 1000
Although TiN and TiCN films are formed using a chemical reaction at a high temperature of ℃, the present inventors have studied in detail the formation of an intermetallic compound of Ni and Ti, and as a result, at a temperature of 920 ° C or lower, the intermetallic compound is formed. We obtained a new finding that does not form.

Generally, when TiCN is formed by the CVD method, N ₂ and CH ₄ are used as source gases and a reaction of 2TiCl ₄ + N ₂ + 2CH ₄ → 2 · TiCN + 8HCl is used. However, this reaction is 950
At a temperature of ℃ or below, the reaction rate is extremely slow, and industrial application is impossible. From the above viewpoint, the present inventors
An MT-CVD method (Mode) using CH ₃ CN gas capable of forming a TiCN film even at a temperature of 20 ° C. or lower (Mode
It was found that the reaction with Ni can be easily prevented by using the rate-temperature CVD method) or the plasma CVD method.

In the case of the CVD method, the reaction remaining in the film is a tensile stress, and the explanation of the reason in the PVD method described above is not applicable, but basically, the TiN film is soft, and the film is formed when it is made into a multilayer. It is common that the grain growth of the particles is suppressed, and the adhesion between the coatings is improved by interposing an intermediate layer in which the C concentration continuously changes in the middle.

In the coated cermet alloy according to the present invention, for example, a part or all of Ti in the TiCN film is Zr,
It is also possible to substitute other metal components such as Cr, Hf, Ta and Al, or to substitute nitrides of these metal components, and the result in this case is the same as the reason described above. Hereinafter, a detailed description will be given based on examples.

[0014]

EXAMPLE 30TiC-30TiN-10WC-10T
Comparative alloy 1 was formed by depositing TiN and TiCN to a thickness of 4 μm on a cermet alloy from aC-5Mo ₂ C-7.5Co-7.5Ni by PVD method and CVD method.
I got ~ 4. In addition, alloys 5 to 9 of the present invention having a multilayer coating were produced by switching the introduced gas in the PVD method and the MT-CVD method. These coated cermet alloys were gradually increased in load from 0 by a scratch tester, and the load for scratching and scratching the film was obtained. The results are shown in Table 1.
It was shown to.

In addition, a cutting test was conducted under the cutting conditions in which the following tools were repeatedly subjected to impact, and the maximum wear was 0.2 mm.
The service life time until the temperature reaches the value is obtained, and the results are shown in Table 2. Cutting conditions Work material (round bar with 4 grooves) S50C
Hs32 Cutting speed 200m / min Feed 0.15mm / rev Depth of cut 2mm Chip shape SNMA432 No cutting oil

[0016]

[Table 1] Film composition Film forming method Comparative alloy 1 TiN PVD 2 TiCN PVD 3 TiN CVD 4 TiCN CVD Inventive alloy 5 TiN-TiCN PVD 6 TiN- (graded TiCN) -TiCN PVD 7 TiN-TiCN-TiN-TiCN- TiN-TiCN PVD 8 TiN-TiCN MT-CVD 9 TiN- (graded TiCN) -TiCN MT-CVD

[0017]

[Table 2] Film thickness Scratch strength (N) Cutting life (min) Comparative alloy 1 4 25 25 (Normal wear) 2 4 6 5 (Abnormal wear due to film peeling) 3 4 3 1 (〃) 4 4 3 1 (〃 ) Alloy of the present invention 5 4 20 55 (normal wear) 6 4 24 60 (〃) 7 4 28 85 (〃) 8 4 45 50 (chipping part 1) 9 4 50 62 (normal wear)

Using the same cermet alloy used in Example 1, super multi-layer coating was carried out to produce alloys 10 and 11 of the present invention. Example 1 was added to the same evaluation, and the hardness of the coating was compared. The results are shown in Table 3.

[0019]

Table 3 Film forming method Micro Vickers hardness Comparative alloy (kg / mm ² ) 1 TiN PVD 2100 2 TiCN PVD 2950 Inventive alloy 5 TiN-TiCN PVD 2900 11 TiN-TiCN 30 layer PVD 3050 12 TiN-TiCN 100 Layer PVD 3080

[0020]

[Table 4] Scratch strength (N) Cutting life (min) Comparative alloy 1 25 25 (normal wear) 2 6 5 (chipping due to film peeling) Inventive alloy 5 20 55 (normal wear) 11 18 90 (〃) 12 18 90 (〃)

[0021]

The coated cermet alloy of the present invention is coated with TiCN, which has a hardness higher than that of conventional TiN, and has excellent wear resistance and a remarkably long tool life. Further, although the present invention has mainly described cermets, it is obvious that the present invention also exhibits excellent effects when applied to cemented carbides.

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Claims (4)

[Claims] 1. A coated cermet alloy for use in cutting tools, wear resistant tools, impact resistant tools, etc., characterized in that the lowermost layer is a TiN film, and is multilayered with TiCN and / or Ti compounds. 2. The coated cermet alloy according to claim 1, wherein an intermediate layer having a continuously changed C concentration is interposed in the middle of the multilayer film. 3. The coated cermet alloy according to claim 1, wherein the multilayer film has 10 or more layers. 4. The coated cermet alloy according to claim 1, wherein part or all of Ti is Zr, Cr,
A coated cermet alloy characterized by being replaced with a metal component of Hf, Ta, Al, a mixture thereof, or a solid solution.