JP2002337003A - Abrasive-resistant coating coated tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coating coated tool capable of simultaneously attaining significantly high oxidation resistance, wear resistance, lubricity, and adhesion for the accommodation of drying and high speed in cutting highly hard steel, and a complex hard coating coated tool capable of attaining further high adhesion by a combination with a conventional coating. SOLUTION: In this abrasive-resistant coating coated tool formed by coating a base surface with a hard coating, the coating is formed by applying coating of at least one layer A, which consists of chemical composition expressed by (Ala Si1-a )(Nx B1-x ), where 0.5<=a<1, 0.5<=x<=1 and which is composed of phases relatively rich in Si and poor in Si. In the layer A, an amolphous microcrystal (Ala Si1-a )(Nx B1-x ) is interposed. The abrasive-resistant coating coated tool is also constituted by alternately performing the coating of at least one layer of chemical composition generally expressed by (TiAl)N with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard film-coated tool used for high-speed cutting of high hardness steel.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Sho 62-56565 discloses the direct cutting of tempered steel for the purpose of improving the efficiency of metal working.
TiAlN represented by JP-A-2-194159
Coatings have been developed and applied to cutting tools. TiAlN
Since the coating has better oxidation resistance than TiN and TiCN, the performance of the cutting tool is remarkably improved in cutting of tempered steel whose cutting edge reaches a high temperature.

However, in recent years, in order to meet the demand for higher efficiency and higher precision of processing, dry cutting has been regarded as important in view of environmental problems and reduction of processing cost in addition to increasing the cutting speed. I have. In such a cutting environment, the welding phenomena between the wear-resistant film coated on the cutting tool surface and the material to be cut (hereinafter referred to as the work material) has a great effect on the cutting performance, and the cutting temperature decreases. As the temperature becomes higher, oxidation resistance is not sufficient even with a TiAlN-based film. That is, the conventional TiN, TiCN, and TiAlN coatings have sufficient cutting performance under such severe cutting environment due to an increase in frictional resistance and progress of oxidation caused by a welding phenomenon with a work material and the like. At present, it is not possible to obtain any further, and it is no longer possible to sufficiently suppress the progress of wear due to oxidation.

In order to solve such a problem, molybdenum disulfide disclosed in JP-A-11-502775 and JP-A-7-164211 are disclosed from the viewpoint of improving the welding resistance.
The cutting tool has been developed in which a lubricating film consisting of tungsten carbide and diamond-like carbon is laminated on the outermost surface of the hard film, but the adhesion of the hard film is poor and the film itself is very brittle. It is poor in oxidation resistance, and cannot be adequately treated in the above cutting environment due to peeling or destruction during cutting, oxidative wear and the like.

From the viewpoint of improving oxidation resistance, there is a case where a third component is added to TiAlN as typified by JP-A-7-237010 and JP-A-10-130620. In fact, a satisfactory improvement in oxidation resistance has not yet been realized by merely adding chromium. Japanese Patent Application Laid-Open No. Hei 8-118106 discloses T
The case of iSiN has also been proposed, but only TiSiN
Thus, the oxidation resistance has not been improved.

Furthermore, the case of interposing the _Si 3 _{N 4} grains and the like to the internal hard coating as seen in JP-A-11-138038 also seen but sufficient for the progress of oxidation through the _Si 3 _{N 4} grain boundary No oxidation resistance has been imparted.

[0007]

In view of these circumstances, the present invention provides a hard layer which can cope with dry and high-speed cutting, that is, which has excellent oxidation resistance and low adhesion to a work material. It is an object of the present invention to provide a wear-resistant film-coated tool capable of simultaneously realizing oxidation resistance and welding resistance and capable of cutting high-hardness steel dry at high speed.

[0008]

The inventor of the present invention has conducted detailed studies on the wear resistance of a hard coating, its effect on various work materials and reduction of frictional resistance, and the layer structure of the coating.
(Al _a Si _1-a ) (N _x B) that imparts welding resistance
_1−x ), provided that 0.5 ≦ a <1.0, 0.5 ≦ x ≦
Hard coating-coated tool improved in welding resistance by coating layer A having the chemical composition represented by 1.0, and furthermore, by controlling the crystal morphology, simultaneously imparted oxidation resistance and wear resistance. As a result, the present inventors have found that the performance of a cutting tool becomes extremely good in dry high-speed cutting of high-hardness steel, and have reached the present invention. The layer A realizes a coated tool having more excellent adhesion by combining with a general TiAlN-based hard film or the like. It is desirable that the abrasion resistant film is coated by a physical vapor deposition method.

[0009]

First, the function of each component of the layer A will be described in detail. (Al _a Si _1-a ) (N _x B
_1−x ), provided that 0.5 ≦ a <1.0, 0.5 ≦ x ≦
The nitride or boride composed of Al and Si having the chemical composition of 1.0, has a coefficient of friction with steel at room temperature in the air of 0.8% of that of the conventional TiAl nitride film.
Although the friction is as low as 0.5 as compared with the above, especially under high temperature, the value is drastically reduced to around 0.3. It was confirmed that this was caused by the fact that Si in the film was diffused inside the film surface at a high temperature due to a reaction with the cutting powder, and a low melting point Si oxide was formed on the film surface.

The low melting point Si oxide makes (Al _a S
It was confirmed that the i _1-a ) (N _x B _1-x ) film functions as a lubricating film having excellent lubricating properties and has an action of suppressing an increase in cutting resistance due to welding. Further, by the addition of boron, boron forms a BN phase inside the film,
It has been clarified that the lubricating effect of the BN phase is further improved.

The present inventors have conducted intensive studies on the improvement of oxidation resistance, and as a result, have found that (Al _a Si _1-a ) (N _x B _1-x )
The crystal morphology of the phase has a great influence on the oxidation resistance, and by controlling the crystal morphology, it is possible to impart oxidation resistance superior to (TiAl) N-based coatings, which are generally said to have excellent oxidation resistance. That led to the surprising finding. The (Al _a Si _1-a ) (N _x B _1-x ) phase has a different crystal form depending on the ion energy at the time of coating, and when the ion energy is low, it exhibits an amorphous crystal as a whole and includes Si ₃ N ₄ therein. It is in the form of intervening particles. When the ion energy is high, the overall state is close to an amorphous state, and a state in which a bond between Si and N is confirmed in AlNB. When the ion energy is moderate and the coating temperature is 550 ° C. or higher, a completely amorphous AlSiBN phase exists in the form of fine crystals.
The Si content of the iBN phase is determined by the crystalline A
It was confirmed that the form became richer than the Si content of the lSiBN phase. It was confirmed that when the temperature was low, a crystal form similar to that when the ion energy was high was exhibited. The reason for the correlation between temperature, ion energy and crystal morphology requires future physical studies.

Above all, when the completely amorphous AlSiBN phase exists as fine crystals, the crystal grain boundaries become very aligned grain boundaries, there are few defects, diffusion of oxygen at the grain boundaries is remarkably suppressed, and excellent oxidation resistance is obtained. It was confirmed to have. At the same time, a dense Al oxide was formed on the outermost surface during oxidation, and a dense Si oxide was also formed immediately below the Al oxide, thereby further suppressing the diffusion of oxygen into the inside of the film. At the same time, by interposing fine crystals, the matrix was strengthened in lattice strain, the hardness was improved, and as a result, the wear resistance was also improved.

The coating conditions are such that the ion energy is relatively moderate, an applied bias of -100 V to -150 V, a reaction pressure of about 1 Pa to 5 Pa, and a coating temperature of 550.
C. or higher is a preferable range.

The composition of the metal element of the layer A constituting the hard coating of the present invention is such that the value of _a in (Al _a Si _1-a ) satisfies the expression 0.5 ≦ a <1.0. is necessary. When the value of a is less than 0.5, the Si content becomes too large, the toughness of the film itself is deteriorated, and the internal destruction of the film and the peeling of the film accompanying the destruction become remarkable in dry high-speed cutting, and sufficient performance is obtained. Can not be demonstrated.

[0015] In the case of nitrides or窒硼product according to the A _layer, it is necessary to satisfy 0.5 ≦ x ≦ 1.0 with N _{x B 1-x,} the value of x is 0. If less than 5,
The hardness of the coating is significantly increased, the residual compressive stress is increased, and the adhesion of the coating is deteriorated, so that sufficient cutting performance is not exhibited.

When the fine crystal grain size of the amorphous AlSiBN phase exceeds 500 nm, the effect of lattice distortion is small and the contribution of improving the hardness of the film is reduced, so that it is more preferably 500 nm or less. The A layer has excellent low friction and high oxidation resistance under static and dynamic conditions, but is suitable for dry high-speed cutting of hardened steel with an HRC of more than 60.
With a single film, adhesion may not be sufficient and peeling may occur. Therefore, lamination with a (TiAl) N layer or the like having excellent adhesion resistance and abrasion resistance is a more preferable result in such high-hardness steel cutting.

It goes without saying that the (TiAl) N layer used here may have the same effect even if the third metal component is added in some cases.

The method of coating the hard film-coated tool of the present invention is not particularly limited, but in consideration of the thermal effect on the coated base material, the fatigue strength of the tool, the adhesion of the film, etc. Arc discharge ion plating that can be coated at a relatively low temperature and compressive stress remains in the coated film,
Alternatively, a physical vapor deposition method of applying a bias voltage to the coated substrate side such as sputtering is preferable.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. A
Evaporation of metal components using the ion plating system
The source is a target made of various alloys and a reaction gas.
N ₂Select a gas that provides the desired film from the gas,
Conditions of 600 ° C. substrate temperature and 3.0 Pa reaction gas pressure
, 2 blades made of cemented carbide with an outer diameter of 10 mm, which is the coated substrate
-130V for end mills and cemented carbide inserts
Potential so that the total thickness of all coatings is 1 μm.
Filmed. In addition, boron and Si are necessary for the target, which is the evaporation source.
The required amount was added. Table 1 shows the prototypes of the present invention and comparative examples.
Show. In the case of a multilayer, the total thickness of layer A is 0.5 μm, and the total thickness of other layers is 0.5 μm.
The coating was evenly applied to 1.5 μm.

[0020]

[Table 1]

A cutting test was performed using the obtained hard-coated end mill and hard-coated insert. The tool life was defined as the cutting length when the tool could not be cut due to chipping or wear of the cutting edge. Table 1 also shows the obtained results.

The cutting conditions of the two-flute carbide end mill are side cutting down cut, work material S50C (hardness HB22).
0), incision Ad10mm × Rd1mm, cutting speed 2
50 m / min, feed 0.06 mm / tooth, and use of air blow.

The insert cutting conditions are as follows: Tool shape SEE4
2TN, 100mm width x 250mm length chamfering,
Work material SKD61 (hardness HRC45), depth of cut 2.0
mm, cutting speed 150m / min, feed 0.15mm /
rev, dry cutting. Table 1 also shows the test results.

The oxidation resistance was 9 μm for each coating.
The evaluation was made based on the thickness of an oxide layer formed when the substrate was kept in the air at 00 ° C. for one hour. The coefficient of friction is SKD6 at 600 ° C.
Using one ball, the measurement was performed by a general ball-on-disk method. Table 2 shows the measured results.

[0025]

[Table 2]

Comparative Examples 16 and 17 are cases in which the amount of Si or boron is too large. Although the static evaluation values are satisfied, the adhesion is not sufficient and the tool life is short. Comparative Examples 13, 14, and 15 are examples in which the third component was added to the TiAlN-based coating, and although the oxidation resistance was improved,
The improvement effect is less than that of the example of the present invention.

On the other hand, the examples of the present invention are excellent in static evaluation characteristics and also excellent in adhesiveness, and are free from abnormal wear, film oxidative wear and film peeling due to the welding phenomenon. Tool life is significantly improved. Therefore, the present invention is sufficient for dry high-speed cutting of high hardness steel.

[0028]

As described above, the hard-coated tool of the present invention has particularly excellent oxidation resistance as compared with conventional coated tools,
Since it has high adhesion and low friction at the same time, extremely long tool life can be obtained in dry high-speed cutting, which is extremely effective in improving productivity in cutting.

[Brief description of the drawings]

FIG. 1 shows (Al _a Si _1-a ) (N
_x B _1-x) fine amorphous crystals interposed in the matrix _{(Al a Si 1-a)} TEM of (N _{x B 1-x)}
An image is shown.

FIG. 2 corresponds to spot 1 in FIG.
₂ shows a microelectron diffraction image of _a Si _1-a ) (N _x B _1-x ).

FIG. 3 corresponds to spot 2 in FIG. 1 (Al
_aSi_1-a) (N_xB_1-x) Interposed in the matrix
Fine amorphous crystals (Al_aSi_1-a) (N_x
B _1-x2) shows an ultra-fine electron diffraction image.

Claims (4)

[Claims] 1. A hard film, (Al _a S
i _1-a ) (N _x B _1-x ), provided that 0.5 ≦ a <1,
In a wear-resistant coating tool coated with at least one layer A having a chemical composition represented by 0.5 ≦ x ≦ 1, the A layer is a relatively Si-rich AlSi (N _x B _1-x ) phase. abrasion coating coated tool, characterized in that it is composed of relatively Si less _{AlSi (N x B 1-x} ) phase and. 2. The tool according to claim 1, wherein said relatively Si-rich AlSi (N _x B _1-x ) phase is an amorphous phase. 3. The tool according to claim 1, wherein said relatively Si-rich AlSi (N _x B
_1-x ) A tool coated with a wear-resistant coating, wherein the phase has a crystal grain size of 500 nm or less. 4. The tool according to claim 1, wherein said A layer and a nitride containing Ti and Al as main components;
A tool having a wear-resistant coating, wherein two or more layers of carbonitride, nitride oxide and boride are laminated.