JPH0941127A - Hard film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a hard film superior in wear resistance to an (Al,Ti)(N,C) type film, which has the most excellent wear resistance among the conventional TiN film, TiC film, TiCN film, and (Al,Ti)(N,C) type film, and having wear resistance capable of meeting the demand for high speed cutting. SOLUTION: This hard film has a composition represented by (Al1-y Xy )Z, where X and Z mean one element among Cr, V, and Mg and one element among N, C, B, Cn, BN, and CBN, respectively, and 0<y<=0.3 is satisfied.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hard coating,
Specifically, it relates to a hard coating excellent in wear resistance, and in particular,
It belongs to the technical field of a hard coating suitable as a wear-resistant hard coating for tools and dies used for processing such as cutting and punching.

[0002]

2. Description of the Related Art When manufacturing wear resistant members such as cemented carbide (WC-Co based sintered alloy) or high speed tool steel, the purpose is to improve the performance such as wear resistance. A wear-resistant film made of metal nitride or carbide is formed on the surface of the base material of those members.

Examples of such wear resistant coatings include TiN coatings and
A TiC film is commonly used, and it is formed by the ion plating method. Comparing this TiN coating with the TiC coating, the TiN coating has superior heat resistance (high temperature oxidation resistance) to the TiC coating, and the crater wear on the tool rake surface that rises due to machining heat and friction heat during cutting Although it has a protective function, it has a lower hardness than the TiC coating, so it is rather vulnerable to flank wear that occurs on the flank that contacts the work material. Indicates high durability. Therefore, recently, a hard coating of TiCN that suppresses both crater wear and flank wear has been put into practical use.

By the way, in recent years, along with the labor saving, energy saving and productivity improvement of the cutting process, it has been desired to further increase the cutting speed, and heavy cutting such as high cutting or high feed is performed. . Since the cutting conditions tend to become more severe in this way, the TiN coating, TiC coating,
The TiCN coating is no longer able to meet this demand. That is, when high-speed cutting is performed with a cutting tool having a TiN coating, a TiC coating, or a TiCN coating, Ti in the coating is oxidized at a high temperature and the coating deteriorates, resulting in extremely severe wear.

Therefore, as a hard coating having more excellent wear resistance, TiN, TiC, or TiCN has a third layer other than Ti, N, and C.
It has been attempted to add a fourth element, and Al is added as the element, and a composite nitride of Ti and Al [(Al, Ti) N], a composite carbide [(Al, Ti) C] or a complex carbonitride [(Al, Ti) (N, C)] hard coating (hereinafter collectively referred to as (Al, Ti) (N, C) -based coating) has been proposed. (Japanese Patent Publication No. 4-53642 and Japanese Patent Publication No. 5-67705). This (Al, Ti) (N, C) -based film has Al added to improve heat resistance (high temperature oxidation resistance) and hardness, and Al is selectively oxidized at high temperatures to form a protective film. As a result, oxidation of the film under the film is prevented, and thereby heat resistance is improved. However, as with TiN coating, the coating deteriorates at around 800 ° C, which makes it unsuitable for high-speed cutting where the cutting edge temperature is said to be 1000 ° C or higher, and the hardness of the coating is too high at Hv2500. Not expensive,
Furthermore, there is a need for hard coatings with improved performance (especially abrasion resistance).

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is to achieve the above-mentioned object.
It eliminates the problems of TiN coating, TiC coating, TiCN coating, and (Al, Ti) (N, C) coating, and has the highest wear resistance among these conventional coatings (Al, Ti) ( The present invention is intended to provide a hard coating having better wear resistance than N, C) -based coatings.

[0007]

In order to achieve the above object, the hard coating according to the present invention is the hard coating according to claims 1 to 3, which has the following constitution.

That is, the hard coating according to claim 1 is made of Al and X.
(X: Cr, V, Mg, one type) compound nitride, compound carbide,
Compound boride, compound carbonitride, compound boronitride, compound carbon boride or compound carbonitride boride, with Al and X
The composition is (Al _1-y X _y ), where X is _{one of} X, Cr, V, and Mg 0 <y ≦ 0.3.

The hard coating according to claim 2 has a thickness of 0.1 to
The hard coating according to claim 1, having a thickness of 20 μm. Claim 3
The described hard coating is the hard coating according to claim 1 or 2, which is formed on the surface of a cemented carbide (WC-Co based sintered alloy) or high speed tool steel.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The hard film according to the present invention is obtained by, for example, a sputtering method. This hard coating is
It has the above composition, excellent heat resistance (high temperature oxidation resistance), and high hardness, so it has the best wear resistance among conventional coatings (Al, Ti) (N, C). ) It has better wear resistance than the system coating, and has wear resistance that can be used for high speed cutting.

The details will be described below.

The above-mentioned conventional (Al, Ti) (N, C) -based coatings, which have been proposed in order to cope with higher cutting speeds and heavy cutting such as high depth of cut or high feed, have high wear resistance. It is said to be relatively good. It is considered that the reason is that the heat resistance (high temperature oxidation resistance) is improved and the hardness is increased because the oxide film formed by the selective oxidation of Al serves as a protective film. However, in the case of high-speed cutting, the temperature becomes extremely high, so Ti is also oxidized, the film deteriorates, the protective property of the film is lost, and wear becomes severe.
Therefore, those that exclude Ti, namely, AlN film, AlC film,
Although it is considered good to use AlCN coatings (hereinafter these are collectively referred to as Al (N, C) -based coatings), Al (N, C) -based coatings such as AlN usually have a hexagonal crystal system, Therefore, the hardness is Hv
It is as low as about 1000, it is soft as a hard coating used for tools, and its abrasion resistance is extremely low, which is insufficient.

Therefore, as a result of adding various elements to Al (N, C) such as AlN and evaluating the film performance, it was found that the heat resistance was improved by containing a predetermined amount of one of Cr, V and Mg (hereinafter, X). Property (high temperature oxidation resistance) and hardness are improved.
The wear resistance is better than that of Ti) (N, C) -based coatings, and it becomes possible to have wear resistance that can cope with high-speed cutting, and the content of X in Al and X is It was found that the proportion of X in the above should be 30 at% or less. The cause of the improvement in heat resistance and hardness due to the addition of X (that is, one of Cr, V, and Mg) is not clear, but for the composite carbide of Ti and Nb [: (Ti, Nb) C], etc. The relationship between the valence electron distribution and hardness as reported (Su-rface and
Coatings Technology, 33 (1987) 91-103) or the change of crystal system from hexagonal to cubic.

The present invention has been made on the basis of the above findings, and the hard coating film according to the present invention is made of Al and X as described above.
(X: Cr, V, Mg, one type) compound nitride, compound carbide,
Compound boride, compound carbonitride, compound boronitride, compound carbon boride or compound carbonitride boride, with Al and X
(Al _1-y X _y ), where X is _{one of} X, Cr, V, and Mg 0 <y ≦ 0.3.

This hard coating is (Al _1-y X _y ) N, (Al _1-y X _y ) C, where X is _{one of} Cr, V and Mg.
(Al _1-y X _y ) B, (Al _1-y X _y ) CN, (Al
It is characterized by having a composition represented by _1-y X _y ) BN or (Al _1-y X _y ) CBN, and 0 <y ≦ 0.3. Where N, C, B, CN, BN or CB
When N is Z, this hard film has a composition represented by (Al _1-y X _y ) Z and is characterized in that 0 <y ≦ 0.3. In addition, (Al _1-y X _y ): Z is 1: 1.
However, the case of 1: about 1 (1 or less close to 1) is also included, and for example, it may be 1: 0.90.

In other words, Al and X (where X: Cr, V,
A kind of Mg) compound nitride, compound carbide, compound boride,
Compound carbonitride, compound boronitride, compound carbon boride or compound carbonitride boride [ie (Al _1-y X _y ) Z],
The hard coating is characterized in that the proportion of X in Al and X is 30 at% or less (not including 0%).

Therefore, the hard coating according to the present invention has excellent heat resistance (high temperature oxidation resistance) in comparison with the above findings, and
Hardness is high, so it has better wear resistance than the (Al, Ti) (N, C) -based coatings, which have the highest wear resistance among conventional coatings, and wear resistance that can be used for high-speed cutting. It can be seen that it has a property.

Here, the proportion of X in Al and X is 0.
30 at% or less excluding%, that is, _{y in} (Al _1-y X _y ) Z is 0
<Y ≦ 0.3 means that when y is more than 0.3, the components related to Al (that is, AlZ described later) are decreased, the high temperature oxidation resistance and the hardness are deteriorated, and the wear resistance is deteriorated. On the other hand, when y is 0, X is not contained,
This is because the wear resistance cannot be improved by adding X and the wear resistance becomes insufficient.

If (Al _1-y X _y ) Z is described as a solid solution component, it can be expressed as (AlZ) _1-y- (XZ) _y solid solution. Therefore, increasing y reduces the amount of AlZ component. Therefore, if y exceeds 0.3, the amount of AlZ component becomes too small and the above-mentioned inconvenience of deterioration of wear resistance occurs. On the other hand, decreasing y results in increasing the amount of AlZ component, which in turn improves wear resistance. From this point of view, it is necessary to set 0 <y ≦ 0.3, but in order to improve wear resistance more reliably, 0 <y ≦ 0.3
0.2 is desirable, and the closer y is to 0 (except 0), the better the abrasion resistance is. But y
If the value is too small, the amount of the XZ component becomes too small, the crystal system changes from the cubic system to the hexagonal system, and the wear resistance decreases. Therefore, it is preferable to set 0.01 ≦ y from that point.

Regarding the film thickness of the hard film according to the present invention,
Although not particularly limited, when a member such as a tool which is required to have both wear resistance and oxidation resistance is coated with the hard film, the film thickness is preferably 0.1 μm or more. In terms of oxidation resistance, if the hard coating is evenly coated, it is effective even if the film thickness is less than 0.1 μm, but if the film thickness is less than 0.1 μm, the wear resistance imparting effect is not exerted so much, and the wear resistance becomes poor. This is because there is a possibility that it will be sufficient. On the other hand, if the film thickness is more than 20 μm, the effect of improving wear resistance and oxidation resistance is small compared to increasing the film thickness, and since coating time becomes long and productivity decreases, it is recommended to set it to 20 μm or less. Desirable (hard coating according to claim 2).

Further, the substrate coated with the hard coating according to the present invention is not particularly limited,
Various base materials can be used depending on the application and need. For example, in the field of tools, it can be formed on various tool base material surfaces and used as a base material for cemented carbide (WC-Co based calcination). Bonding gold) or high speed tool steel (high speed steel) is preferably used (hard coating according to claim 3). This is because the coating of the present invention has very good adhesion, particularly to cemented carbide and high speed tool steel.

The coating of the hard film according to the present invention on the surface of the substrate is represented by the ion plating method, the sputtering method, or the ion implantation method in which the metal component is ionized by the arc discharge using the cathode as the evaporation source.
It can be performed by the VD method. Among these, to explain the contents of the arc ion plating method, the metal components ionized by arc discharge using the cathode as an evaporation source are reacted in an atmosphere of N ₂ , CH ₄ or BF ₃ gas or a mixed gas thereof, Deposit on the substrate surface to which bias voltage is applied. At this time, Al and C are used as the cathode.
Although r, Al and V, or Al and Mg may be used individually, if Al _1-y X _y consisting of the target composition itself is used as the cathode (target), the control of the film composition is easy. There is an advantage. In this case, the vaporization of Al _1-y X _y is performed in a large current region of several tens of amperes or more, and therefore the compositional deviation of the cathode material (Al _1-y X _y ) hardly occurs,
Moreover, a film having high ionization efficiency and high reactivity, and having excellent adhesion can be obtained by applying a bias voltage to the substrate.

[0023]

【Example】

(Example 1) cathodic arc method using an ion plating device, Al _1-y X _y (where, X: Cr, V, or Mg, y: various changes) as a cathode electrode attached to the target, whereas, the apparatus A tool tip made of cemented carbide (WC-10% Co-based sintered alloy) was attached to the substrate (base material) holder of as a base material. Further, the apparatus was provided with a substrate rotating mechanism and a heater for ensuring the uniformity of the film formation state.

Then, a bias voltage of -30 V is applied to the substrate while the substrate (chip) is heated and held at 400 ° C. by the above heater, and a high-purity N ₂ gas or N ₂ / CH ₄ mixed gas is introduced into the apparatus. was an atmosphere of 1 × 10 ^-3 Torr in terms of the introduction, film formation was carried out with a thickness of 5μm on the surface of the substrate to initiate the arc discharge. The composition of the film thus obtained is shown in Tables 1-2 (N
o.1-33, 36-68). Among these, No. 1-27, 36-62
The thing is a hard coating according to an embodiment of the present invention, No. 28
33 to 63 and 68 to 68 are coatings according to comparative examples.

Further, for comparison, Al _1-y Ti _y or Ti is used for the cathode (target), and an (Al, Ti) N film and a TiN film are formed by the same apparatus and method as above except for such points. did. The compositions of these films are shown in Tables 1 and 2 (No. 3
4, 35, 69, 70).

Using the tool tip thus coated, a cutting test was conducted under the following two conditions. The test results are shown in Tables 1-2. Work Material: S45C, Cutting Speed: 170m / min, Feeding Speed: 0.
25mm / rev, depth of cut: 1mm, cutting time: 25 minutes Work material: SKD11, cutting speed: 150m / min, feed rate: 0.
2mm / rev, depth of cut: 2mm, cutting time: 25 minutes

As can be seen from Tables 1 and 2, the tool tips having the coating according to the examples of the present invention are different from the tool tips having the coating according to the comparative example in the flank wear amount (wear width: wear). The width of the area) and the depth of rake face wear are extremely small, and the wear resistance is very good.

(Example 2) In order to investigate the oxidation resistance of the film, a platinum plate was used as a substrate, the thickness of the film formed on the surface of the substrate was 10 μm, and the same as in Example 1 except for these points. A film having the composition shown in Table 3 was formed by the apparatus and method described above. Of these, Nos. 71 to 76 are hard coatings according to the examples of the present invention, and Nos. 77 to 84 are coatings according to comparative examples.

With respect to the platinum plate thus formed with a film, in order to examine the oxidation resistance of the film, using a thermobalance device, the temperature range was raised from room temperature to 1200 ° C., the temperature rising rate was 10 ° C./min,
Atmosphere gas: Dry air, Flow rate of atmosphere gas: 150cc / min
The oxidation test was carried out under the conditions of. Then, the temperature at the point of abrupt weight increase that occurs during the temperature rising process was defined as the oxidation start temperature and was determined. Table 3 shows the results. Also, the Vickers hardness of the coating (load 50 g) was measured. The results are also shown in Table 3.

As is clear from Table 3, the coatings according to the comparative examples are about 600 ° C. for the TiN coating and about 800 for the (Al, Ti) N coating.
Oxidation starts at 0 ° C, whereas the films according to the examples of the present invention each have a high oxidation start temperature and are excellent in high temperature oxidation resistance.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

The hard coating according to the present invention has excellent heat resistance (high temperature oxidation resistance) and high hardness.
Best wear resistance among TiN coating, TiC coating, TiCN coating, and (Al, Ti) (N, C) -based coating. Higher wear resistance than (Al, Ti) (N, C) -based coating. It has excellent wear resistance that can be used for high-speed cutting. Therefore, it can be suitably used as a hard coating for tool base materials for high-speed cutting, and the cutting speed can be further increased. It can be preferably used as a wear-resistant hard coating for tools and dies used for processing such as punching, and the improvement of tool performance and die performance and the improvement of life can be achieved by improving their wear resistance. It has the effect that

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Cai 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Co., Ltd. Kobe Research Institute (72) Inventor Kazuhisa Kawada Takatsuka, Nishi-ku, Kobe-shi, Hyogo Prefecture 1-5-5 stand, Kobe Steel, Ltd. Kobe Research Institute

Claims (3)

[Claims] 1. A composite nitride of Al and X (X: Cr, V, a kind of Mg), a composite carbide, a composite boride, a composite carbonitride, a composite boronitride, a composite carbon boride or a composite carbonitride. And a composition of Al and X is (Al _1-y X _y ), where X is one of Cr, V, and Mg 0 <y ≦ 0.3 Film. 2. The hard coating according to claim 1, which has a film thickness of 0.1 to 20 μm. 3. The hard coating according to claim 1, which is formed on the surface of cemented carbide or high speed tool steel.