JPH08199338A - Coated hard alloy - Google Patents

Abstract

PURPOSE: To improve the oxidation resistance and oxidation-resisting rate of a coated hard alloy and to enable a long tool service life by specifying the molar ratio of the film compsn. of a coated hard alloy in which a part of a hard film having specified components is substituted with Y. CONSTITUTION: A hard film is formed of the one having 0.5 to 15μm film thickness composed, as the main components, of Ti and Al and/or the nitrides, carbonitrides and carbides of their solid solutions. In the film compsn. of the coated hard alloy in which a part of the same main components is substituted with yttrium is expressed by (Tia Alb Yc )Cx N1-x molar ratios, (a), (b), (c) and (x) respectively satisfy a+b+c=1, 0.3<=a<=0.7, 0.3<=b<=0.7, 0.01<c<=0.20 and 0<=x<=1. Thus, excellent effects can be shown even in the case it is applied to TiCN-base cermet and high speed steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated cutting tool used as a cutting tool having excellent wear resistance and fracture resistance and a coated wear resistant tool used as a wear resistant tool.

[0002]

2. Description of the Related Art Conventional hard coatings made by PVD are made of TiN.
Was the mainstream, but recently TiCN film or (TiA
l) A new type of coating such as N has been developed and has been attracting attention. TiCN has a Vickers hardness of about 3000, which is significantly harder than the Vickers hardness of 2200 of TiN, and also has the effect of significantly increasing wear resistance. On the other hand (TiAl)
N varies depending on the ratio of Ti and Al, but is generally 2300
Since it has a Vickers hardness of 2800 and is higher in wear resistance than TiN while being excellent in oxidation resistance, it exhibits excellent characteristics under cutting conditions where the cutting edge has a high temperature.

Further, in order to improve the film of the (TiAl) N film, Japanese Patent Publication No. 5-67705 in which the ratio of Ti / Al is limited, and further multi-component films such as (TiAlZr) N and (TiAlV) N are used in US patents. No. 4,871,434 has been proposed and further improvements are being made. However, although these new coatings have the above-mentioned advantages, they are not yet sufficiently satisfactory in oxidation resistance.

[0004]

The reason for this is the above-mentioned A.
The film containing 1 surely has oxidation start temperatures of TiN and TiC.
Although it is higher than N and has excellent oxidation resistance, the oxidation progress rate is TiN,
It is almost the same as TiCN. That is, the oxide film formed by oxidation is TiN or TiCN.
As in the case of (3), the Al-containing film also has a rutile structure and is a porous film. Therefore, the resistance to the progress of oxidation is extremely low because of the rutile structure.

[0005]

The object of the present invention is to further improve the oxidation resistance of nitride and carbonitride coatings containing Ti and Al, and to provide coatings with a longer life in high speed cutting in which oxidation continues. To do.

[0006]

Therefore, the present invention provides (T
As a result of investigating addition of various elements to iAl) N based on iAl) N, it was found that the addition of Y significantly improved the oxidation resistance. Table 1 shows that a 3 μm (TiAl) N coating was applied with a bias voltage of 12 by arc ion plating.
Y when forming a film under the conditions of 0 V and a nitrogen pressure of 10 ^-1 Pa
The starting temperature of the oxidation in the case of adding Al and the oxidation rate in the air at 850 ° C. are 3 μm of TiN and (Ti _0.5 Al _0.5 ) N.
The result compared with the film is shown.

[0007]

[Table 1]

From Table 1, it can be seen that the solid solution of Y in the (TiAl) N coating improves the oxidation resistance of the coating. Therefore, according to the present invention, a part of the main component of the hard coating having a film thickness of 0.5 to 15 μm, which is composed of nitride, carbonitride, and carbide of Ti and Al and / or a solid solution thereof as main components, is yttrium-containing. In the molar ratio, the coating composition of the coated hard alloy substituted with (Ti _a Al _b Y
_c ) When expressed as C _x N _1-x , a, b, c and x are respectively a + b + C = 1, 0.3 ≦ a ≦ 0.7, 0.3 ≦ b
≦ 0.7, 0.01 <c ≦ 0.20, 0 ≦ x ≦ 1, and (TiAlY) nitride or carbonitride in which a part of the main component is replaced with Y. , A layer of carbide, A
1 layer of nitride or carbonitride, Ti nitride or carbonitride, or solid solution nitride or carbonitride of TiAl is made into a multi-layer or laminated structure of 5 layers or more to have oxidation resistance and high hardness. Has been achieved.

[0009]

[Function] As described above, Y is contained in the (TiAl) compound film.
It is possible to improve the oxidation resistance of the film by adding. In particular, the reason why the oxidation rate can be remarkably improved is that when Y is added, the form of the oxide film formed shows an anatase structure rather than a rutile structure. In other words, the addition of Y forms a very dense oxide film, and the progress of oxidation is controlled by the diffusion of oxygen in the formed oxide film, whereby the progress of oxidation is significantly suppressed. Therefore, in high-speed cutting where oxidation progresses continuously, oxidation of the coating occurs only on the surface, which acts as a protective film against the oxidation and does not progress to the inside of the coating, resulting in long life. Is.

The reason for limiting the numerical values will be described below. If Y added as a solid solution / mixture in the (TiAl) compound film is 0.01 or less, it is not always sufficient to improve the oxidation resistance, and if it exceeds 0.20, the hardness of the film is remarkably reduced. However, since there is a tendency for remarkable deterioration, the range of 0.01 <c ≦ 0.20 was set. The same effect can be obtained by solidifying the above elements as a target material, adjusting the components during vapor deposition using each element as an individual target, and further combining the solid solution target and the individual target.

Next, when the amount of Ti exceeds 0.7, the content of Al decreases on the contrary, the oxidation resistance deteriorates, and when it is less than 0.3, the hardness is remarkably lowered. a ≦ 0.
It was set to 7. The ratio of CN in the film is 0 ≦ x ≦ 1, that is, the range of carbides, nitrides, and carbonitrides is (Ti
(Al) Since the oxidation resistance is improved by the effect of Y added as a solid solution / mixture in the film, it is possible to sufficiently use a carbide having a poorer oxidation resistance than a nitride, and a nitride having a slightly low hardness, Even in carbonitrides, there is no extreme deterioration in wear resistance, so the range was 0 ≦ x ≦ 1. In addition, if the number of layers or the number of layers is 5 or more, the grain size of the individual layers cannot be reduced and the hardness cannot be improved. Hereinafter, the present invention will be described in detail with reference to Examples.

[0013]

Example 1 84WC-3TiC-1TiN-3TaC
Commercially available 2.5 μm WC powder, 1.5 μm TiC powder, same TiN powder, 1.2 μm so as to have a composition of −9 Co.
m TaC powder was mixed in a ball mill for 96 hours, and after dry granulation, the TA insert of SNMG432 was pressed, sintered, and processed into a predetermined shape. The PVD method was used to form the coatings shown in Table 2 on the cemented carbide substrate by using targets of various (TiAlY) alloys. For comparison, the film described in the conventional example was also formed.

[0014]

[Table 2]

Then, the throw-away insert coated with these films is gradually heated in the atmosphere,
The temperature at which increased oxidation was observed was measured. In the atmosphere, 90
At 0 ° C., the amount of increased oxidation was measured over time, and the oxidation rate was calculated. These results are also shown in Table 2. Furthermore,
A cutting test was performed under the following high-speed cutting conditions to find the time until the maximum wear reaches 0.2 mm, and the results are also shown in Table 2. Work Material S50C (Hs32) Cutting Speed 300m / min Feed 0.15mm / rev Depth of Cut 1mm No Cutting Oil

From Table 2, it is clear that the coating containing Y has a remarkably slow oxidation rate, and that this contributes to a significantly long life in continuous high-speed cutting.

[0017]

Example 2 The same cemented carbide throw-away insert used in Example 1 was used to carry out multilayer or lamination of the coating component system shown in Table 3. In this case, the total thickness of the film is 8 μm
Unified. Next, the oxidation resistance was evaluated in the same manner as in Example 1, and the results are shown in Table 4. In addition, Table 4 also shows the results of measuring the hardness with an ultramicro Vickers (load: 10 g).

[0018]

[Table 3]

[0019]

[Table 4]

From Table 3, it is clear that the improvement of hardness is recognized by the multi-layer or lamination, and the remarkable improvement of hardness is recognized in the case of 1600 layers (5 nm per layer).

[0021]

The coated hard alloy of the present invention is the same as the conventional Ti alloy.
By adding Y as compared with N and TiAlN, the oxidation resistance, especially the oxidation resistance rate is improved, and a remarkably long tool life can be obtained. Further, although the present invention has been mainly described for cemented carbide, it is self-evident that it exerts an excellent effect when applied to a TiCN-based cermet and when applied to high speed steel.

Claims (2)

[Claims] 1. A main component of a hard coating having a film thickness of 0.5 to 15 μm, which is composed of nitride, carbonitride, and carbide of Ti and Al and / or a solid solution thereof as a main component.
When the coating composition of the coated hard alloy in which the part is replaced by yttrium is expressed as (Ti _a Al _b Y _c ) C _x N _{1-x in a} molar ratio, a, b, c and x are respectively a + b + C =
1, 0.3 ≦ a ≦ 0.7, 0.3 ≦ b ≦ 0.7, 0.0
A coated hard alloy, which is a film consisting of 1 <c ≦ 0.20 and 0 ≦ x ≦ 1. 2. The coated hard alloy according to claim 1, wherein
A layer of (TiAlY) nitride, carbonitride, or carbide in which a part of the main component is replaced with Y, and a nitride or carbonitride of Al, or a nitride or carbonitride of Ti, or Ti.
A coated hard alloy, characterized in that a layer composed of a nitride or carbonitride of a solid solution of Al is formed into a multilayer or laminated structure of five or more layers.