JPH07188901A - Coated hard alloy - Google Patents

Abstract

PURPOSE:To reduce the residual compressive stress of an alloy, to increase the adhesiveness of a film, furthermore to improve the peeling resistance of a coated tool and simultaneously to thicken the film by adding elements having hardness lower than that of TiN and TiAlN and allowing the same to enter into solid solution. CONSTITUTION:In the case the compsn. of a film of a film hard alloy of coating hard metal in which a part of Ti in the hard film with 0.5 to 10mum film thickness consisting essentially of Ti and Al and/or the nitrides and carbides of the solid solution thereof is substituted by Fe-based metal and/or Cr is expressed by (TiaAlbFe-based cCrd), (a), (b), (c), (d) and (x) are respectively regulated to the ranges of a+b+c+d=1, a; 0.3 to 0.7, b; 0.3 to 0.7, c; 0.01 to 0.2, d; 0 to 0.1 and x; 0 to 1. Thus, the defect of the high residual stress of a PVD film is improved, by which the service life of a coated cutting tool can be prolonged.

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 member used as a cutting tool having excellent wear resistance and fracture resistance and a coated wear resistant member 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 the TiCN film was replaced by (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 improves wear resistance as compared with TiN, but has extremely excellent 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, these new coatings have the above-mentioned advantages, but the residual compressive stress in the coating is as high as 1.5 times or more that of the TiN coating, and they have the following various problems.

[0004]

The adhesion of the coating becomes weaker as the residual compressive stress of the coating becomes higher, and the adhesion of these new coatings is inferior to that of TiN. In addition, the high residual stress not only deteriorates the adhesion of the film, but also increases the residual stress as the film thickness increases, which is a technical obstacle to thickening the film and realizes thickening. The current situation is that it has not been done.

The simplest way to reduce the residual compressive stress is to modify the coating parameters in the coating process. The inventors of the present invention have examined the nitrogen partial pressure and the residual compressive stress of the bias voltage, which are coating parameters, when TiN is deposited to a thickness of 3 μm on a steel substrate by the arc ion discharge method. Two
The residual compressive stress of −5 GPa was exhibited at the same GPa of −100 V. Further, in the 10 ^-1 Pa under the窒系partial pressure -1 GPa, in the 10 ⁰ Pa showed residual compressive stress of -2GPa. Although the residual compressive stress can be easily changed by changing the film parameters in this way, the arc ion discharge method and the holocalitate method have the respective optimum parameter ranges and the film formation by changing the parameters. Due to the fact that the film properties of the applied film are completely different,
It was not possible to reduce the residual compressive stress by changing the parameters.

[0006]

The object of the present invention is to improve the above-mentioned drawbacks of high residual compressive stress, improve the adhesion of the coating by reducing the residual compressive stress, and at the same time improve the peeling resistance of the coated tool and at the same time increase the thickness of the thick film It provides a technology that makes it possible.

[0007]

Therefore, the present invention is based on (Ti
As a result of studying addition of various elements to Al) N as a basis, the following findings were obtained. Table 1 shows 3 μm (TiA
l) The residual compressive stress when various elements are added when the N film is formed by the arc ion plating method under the condition of bias voltage of 120 V and nitrogen pressure of 10 ^-1 Pa. The respective residual compressive stress when 1 is set to 1 are shown.

[0008]

[Table 1]

It can be seen from Table 1 that the residual stress in the film tends to decrease by dispersing the soft metal in the (TiAl) N film or by making it into a solid solution. Therefore, in the present invention, 0.5 to 10 μm composed of Ti and Al and / or their solid solution nitrides and carbonitrides as main components.
In a molar ratio, the coating composition of the coated hard alloy in which a part of Ti of the hard coating having the film thickness of 1 is replaced by Fe group metal and / or Cr is (Ti _a Al _b Fe group _c Cr _d ) C _x N
_When expressed as _1-x , a, b, c, d, and x are respectively a + b + c + d = 1 0.3 ≤ a ≤ 0.7 0.3 ≤ b ≤ 0.7 0.01 ≤ c ≤ 0.2 0 ≦ d ≦ 0.1 0 ≦ x ≦ 1 and the film is made thicker by forming the film into a multilayer of 5 or more layers.

[0010]

[Function] By adding Fe group and Cr to the (TiAl) compound film, the residual stress in the film is reduced, and the film is also resistant to impact, especially against mechanical impact such as intermittent cutting. It becomes a film that is difficult to do. Furthermore, in the case of the Fe group, a part of Al (CoA
It can be formed as a compound such as l) or (NiAl), and the wear resistance and oxidation resistance of the film can be improved together. The same effect can be obtained in the case of the Cr group, and the oxidation resistance and heat resistance are improved. The reason for limiting the numerical values will be described below.

If the Fe group added as a solid solution / mixture in the (TiAl) compound film is less than 0.01, there is no sufficient effect to reduce the residual stress, and if it exceeds 0.2, the Fe group in the film is present. Therefore, the wear resistance, the welding resistance and the like are deteriorated, so that 0.01 ≦ c ≦ 0.2 is set. Further, although Cr added as a solid solution / mixture in the (TiAl) compound film correlates with the Fe group content, it is alloyed with the Fe group to enhance its oxidation resistance and the like.
If it is added in excess of 1, the amount of Cr in the film becomes too large and there is no sufficient effect for reducing the residual stress, so 0 ≦ d ≦
The range was 0.1. The same effect can be obtained even when the above-mentioned elements are made into a solid solution as a target material, or when each element is used as an individual target to adjust the components at the time of vapor deposition, or when the solid solution target and the individual target are further combined.

The ratio of CN in the film is 0 ≦ x ≦ 1, that is, the range of carbides, nitrides and carbonitrides is (T
iAl) Fe group added as a solid solution / mixture in the film,
Since the stress is relaxed by the effect of Cr, even carbides with high hardness can be sufficiently used, and nitrides with slightly lower hardness,
The carbonitride also has sufficient performance by adjusting the amounts of Fe group and Cr, so the range was set to 0 ≦ x ≦ 1.
Hereinafter, the present invention will be described in detail with reference to Examples.

[0013]

EXAMPLE 84WC-3TiC-1TiN-3TaC-
Commercially available 2.5 μm WC powder with a composition of 9Co,
1.5 μm TiC powder, the same TiN powder and 1.2 μm TaC powder were mixed in a ball mill for 96 hours, dried and granulated, and then the TA insert of SNMA432 was pressed, sintered and processed into a predetermined shape. . P on this cemented carbide substrate
Various alloy targets and targets containing each element alone were prepared by the VD method, and the coatings shown in Table 2 were formed.
For comparison, the film described in the conventional example was also attached.
Then, these coatings are scratched with a scratch tester.
Then, the load was gradually increased and scratched, and the load for peeling the film was determined. The results are shown in Table 2.

[0014]

[Table 2]

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 No cutting oil

From the results shown in Table 2, it can be seen that there is no clear difference in the scratch load, but in the impact resistance test in which a mechanical impact is applied, peeling occurred at the initial stage of use, causing abnormal wear. Although a nitride film was used in the examples, carbonitrides having various composition ratios can be manufactured by adjusting the partial pressure of nitrogen, methane, etc. in the atmosphere during vapor deposition.

[0017]

The coated hard alloy of the present invention is the same as the conventional Ti alloy.
By adding / solid-solving an element having a lower hardness than N and TiAlN, the wear resistance and mechanical shock resistance are excellent, and a significantly long tool life can be obtained. Further, although the present invention has mainly described cemented carbide, it is self-evident that the present invention also exhibits excellent effects when applied to a TiCN-based cermet.

Claims (2)

[Claims] 1. 0.5 to 1 composed mainly of nitride and carbonitride of Ti and Al and / or a solid solution thereof.
In a molar ratio, the coating composition of the coating hard alloy obtained by substituting a part of Ti of the hard coating having a thickness of 0 μm with the Fe group metal and / or Cr is (Ti _a Al _b Fe group _c Cr _d ) C _x N _When expressed as _1-x , a, b, c, d, and x are respectively a + b + c + d = 1 0.3 ≤ a ≤ 0.7 0.3 ≤ b ≤ 0.7 0.01 ≤ c ≤ 0.2 0 A coated hard alloy, which is a coating in the range of ≦ d ≦ 0.1 0 ≦ x ≦ 1. 2. The coated hard alloy according to claim 1, wherein
A part of Ti is replaced with Fe and / or Cr (Ti
FeCr) nitride, carbonitride layer and Al nitride layer are formed into a multilayer of 5 or more layers.