JP2850396B2 - Method of manufacturing high-speed steel cutting tool coated with boron nitride thin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a boron nitride thin film-coated high-speed steel cutting tool.

[Prior Art] High-speed steel is one that has excellent hardness and toughness for high-speed cutting and is widely used as a material for cutting tools.
In recent years, attempts to extend the tool life by providing a hard titanium carbide thin film or titanium nitride thin film on the surface of this high-speed steel to improve the seizure resistance and wear resistance of the high-speed steel tool have been actively conducted on an industrial scale. Began to take place. The prolongation of tool life by this thin film coating greatly contributes to the improvement of the mechanical wear resistance of the tool by the thin film on the tool surface of high hardness, and the improvement of the chemical stability of the thin film on the tool surface at high temperatures. Is also involved.

In the field of tools in which this thin film coating is rapidly spreading, cubic boron nitride (hereinafter referred to as “c- BN ”). This is because c-BN has properties of higher hardness than titanium carbide and titanium nitride, and is also extremely excellent in heat resistance and chemical stability. Therefore, if this c-BN itself or a substance containing c-BN can be coated on the tool surface, a tool with a long life that far exceeds the tool life of the thin film coating tool currently in practical use will be realized. .

However, the c-BN has a few hundred degrees and several GPa.
Therefore, if this c-BN is to be applied to the field of tools, c-BN synthesized in the form of granules or powder under high temperature and high pressure is dispersed on the tool surface. Or by applying the c-BN powder sintered body to the tool surface and applying it.For this reason, due to the complexity of the manufacturing process and the high cost, tools using c-BN are It has not become more widespread than thin film coating tools such as titanium carbide and titanium nitride.

If the tool surface can be coated with c-BN or a material containing c-BN like a conventional thin-film coating tool made of titanium carbide or titanium nitride, c-BN will be applied to the tool field dramatically. no doubt.

As a method for producing the c-BN thin film, for example, there is a chemical vapor deposition method (CVD method). In this CVD method, a substrate is placed in a reaction chamber, a source gas is supplied, and the gas is reacted on the heated substrate to form a boron nitride thin film.

However, the tempering temperature of the high-speed steel is around 500 ° C. to 650 ° C., so that when the high-speed steel is exposed to a temperature higher than this, the steel is softened. Therefore, in order to form a boron nitride thin film on a high-speed steel substrate by the CVD method, it is necessary to heat the substrate at a temperature of 500 ° C. to 600 ° C. or less. Thin films cannot be formed by CVD.

For the above reasons, when forming a boron nitride thin film containing c-BN on a high-speed steel substrate, only physical vapor deposition (PVD) is used.
However, c-BN is not widely used industrially at present because c-BN has high chemical stability and thus has extremely poor adhesion to a substrate.

As a method for solving the above problem, for example,
There are methods disclosed in 63372 and JP-A-60-181262. In this method, by incorporating an ion irradiation method into a film forming process, a vapor deposition material collides with and bounces off the irradiation ions and penetrates into the inside of the substrate, thereby forming a mixed layer of the substrate, the vapor deposition material, and the irradiation ions, This is a method for forming a boron nitride thin film having excellent adhesion to a substrate.

[Problems to be solved by the invention]

However, according to the method described above, when the base is made of high-speed steel, in particular, due to poor affinity between the base and the boron nitride thin film containing c-BN, it has sufficient adhesion to be used as a tool. There is a problem that a boron nitride thin film cannot be obtained.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a boron nitride thin film-coated high-speed steel cutting machine that can significantly improve the adhesion between a high-speed steel and a boron nitride thin film, particularly a hard boron nitride thin film containing c-BN. A method for manufacturing a tool is provided.

[Means for solving the problem]

The method for producing a boron nitride thin film-coated high-speed steel cutting tool according to the present invention is a method for forming a boron nitride thin film with a single apparatus, wherein nitrogen ions are implanted at an energy of 500 eV to 4 eV.
0 KeV, and the nitrogen ion implantation amount is 1 × 10 ¹⁴
1 / cm ² to 1 × 10 ¹⁶ pieces / cm ² , a first step of injecting into the surface of the high-speed steel substrate, vapor deposition of a substance containing boron,
The second step in which the irradiation with the ion species containing nitrogen ions is used in combination is continuously performed to form a boron nitride thin film containing c-BN.

FIG. 1 is a conceptual diagram of a thin film forming apparatus used for carrying out the present invention.

A high-speed steel substrate 2 on which a boron nitride thin film is to be formed is fixed to a holder 1. An ion source 3 and a vapor deposition source 4 are arranged to face the high-speed steel base 2. Holder 1, ion source 3,
The evaporation source 4 and the like are housed in a vacuum vessel (not shown), and the vacuum vessel is maintained at a pressure suitable for film formation.

The ion source 3 of the embodiment is a bucket-type ion source that uses a multipolar magnetic field for confining plasma, and ionizes a gas supplied into the ion source to generate a uniform large-area ion beam of the high-speed steel substrate 2. Although the surface can be irradiated, the present invention is not limited to the above bucket type ion source,
Other ion sources, such as a Kauffman type, can be used.

Using such a thin film forming apparatus, first, the inside of the vacuum vessel is evacuated to, for example, 10 ^-5 to 10 ^-8 Torr, and then nitrogen gas is ionized and accelerated by the ion source 3 to inject nitrogen ions into the high-speed steel substrate 2. (First step).

The implantation energy of the nitrogen ions is 100 eV to 100 keV.
Can be appropriately selected within the range of 500 eV to 40 keV in consideration of the range of nitrogen ions in the high-speed steel substrate 2.
It is desirable to select within the range.

The nitrogen ion implantation amount is 1 × 10 ¹³ / cm ² -1.
It can be appropriately selected within the range of × 10 ¹⁷ pieces / cm ² ,
Considering the wear resistance of the high-speed steel substrate 2 itself, 1 × 10 ¹⁴
It is desirable to select within the range of pcs / cm ² to 1 × 10 ¹⁶ pcs / cm ² .

Next, on the surface of the high-speed steel substrate 2, a boron-containing compound or a boron-only vapor deposition material 5 is vapor-deposited by a vapor deposition source 4, and simultaneously or alternately, an ion species containing nitrogen ions is irradiated by an ion source 3. On the high speed steel substrate 2
A boron nitride thin film containing BN is formed (second step).

As a gas supplied to the ion source 3 to irradiate the ion species containing nitrogen ions, a nitrogen gas or a nitrogen-containing gas (for example, ammonia or the like) can be used.

Further, a gas obtained by adding at least one of an inert gas and a hydrogen gas to the above-mentioned gas may be used.

When a nitrogen gas or a nitrogen-containing gas and the above-mentioned additive gas are supplied to the ion source 3, the supply ratio of this gas is as follows:
Although not particularly limited, it is preferable that the partial pressure of the additional gas is suppressed to be equal to or lower than the partial pressure of the nitrogen gas or the nitrogen-containing gas. Outside this range, the c-BN content in the formed boron nitride thin film decreases, and a hard boron nitride thin film cannot be obtained.

In order to make the boron nitride thin film formed on the high-speed steel substrate 2 hard, the energy of the ions irradiated from the ion source 3 in the second step should be selected within the range of 200 eV to 40 keV. Preferably, the ratio (B / N) of boron atoms to nitrogen atoms reaching the high-speed steel substrate 2 is preferably selected in the range of 0.5 to 40. Outside this range, the c-BN content in the formed boron nitride thin film decreases, and a hard boron nitride thin film cannot be obtained.

Further, the thickness of the boron nitride thin film is preferably 1 μm or more in order to sufficiently bring out the characteristics of the boron nitride thin film coating.

In this manner, the first step and the second step are continuously performed in the same single apparatus. In the first step, nitrogen ions are implanted into the high-speed steel base 2 by the ion source 3, and in the second step, By combining the deposition of a substance containing boron evaporated from the deposition source 4 and the irradiation of ion species containing nitrogen ions from the ion source 3, a boron nitride thin film containing c-BN is formed on the high-speed steel substrate 2. Form.

[Action]

In the method for producing a high-speed steel cutting tool coated with a boron nitride thin film according to the present invention, in the first step, nitrogen gas is ionized and accelerated by an ion source 3 to inject nitrogen ions into the high-speed steel substrate 2 to thereby increase the nitrogen ion. Nitrides the surface of the high speed steel substrate 2. Thereby, the hardness of the surface of the high-speed steel substrate 2 itself can be increased, and the affinity between the high-speed steel substrate 2 and the boron nitride film containing c-BN formed in the second step can be increased.

Next, in the high-speed steel substrate 2, a substance containing boron evaporated from the evaporation source 4 is pushed into the high-speed steel substrate 2 by ion species including nitrogen ions from the ion source 3, and further, Species penetrate into the high-speed steel substrate 2 to form a mixed layer of the substance and the ionic species evaporated from the high-speed steel substrate 2 and the evaporation source 4, and nitridation with high adhesion on the high-speed steel substrate 2 A boron thin film is formed. On this occasion,
Since the surface of the high-speed steel base 2 is nitrided in the first step, the affinity between the high-speed steel base 2 and the boron nitride thin film containing c-BN becomes higher.

Further, by setting the implantation energy of the nitrogen ions within the range of 500 eV to 40 keV, the nitrogen ions collide and recoil on the high-speed steel substrate 2 and enter the high-speed steel substrate 2 when entering. Damage to the high-speed steel substrate 2 can be reduced, and a rise in the temperature of the high-speed steel substrate 2 can be suppressed.

Nitrogen ion implantation amount is 1 × 10 ¹⁴ / cm ² 〜1 × 10 ¹⁶ / c
By setting it within the range of m ^2, the wear resistance of the high-speed steel substrate 2 itself by nitriding the surface of the high-speed steel substrate 2 is improved, and the boron nitride thin film formed in the second step and the high-speed steel substrate 2 can be improved in affinity.

In order to improve the affinity between the high-speed steel substrate 2 and the boron nitride thin film by nitriding, the injection amount is 1 × 10 ¹⁴ / cm ²
The above is desirable, and the wear resistance of the high-speed steel base 2 itself tends to improve as the injection amount increases from 1 × 10 ¹³ / cm ² to 1 × 10 ¹⁶ / cm ² . × 10 ¹⁷ pieces / cm ²
Is exceeded, the wear resistance tends to be degraded in reverse. Therefore, in order to improve the wear resistance of the high-speed steel substrate 2 itself by nitriding, the wear resistance is preferably less than 1 × 10 ¹⁷ pieces / cm ^2. That's why.

The deterioration of the wear resistance of the high-speed steel substrate 2 is considered to be related to irradiation damage and thermal damage by nitrogen ions, the rate of nitride formation, and the like.

〔Example〕

Example 1 In the thin film forming apparatus shown in FIG. 1, after a vacuum vessel (not shown) was evacuated to a degree of vacuum of 1 × 10 ⁻⁶ Torr, nitrogen gas having a purity of 99.999% was supplied as a first step, and energy was injected at 10 keV. The high-speed steel substrate 2 was irradiated with nitrogen ions in an amount of 1 × 10 ¹⁵ / cm ² .

Then, as a second step, 99% pure boron is evaporated from the evaporation source 4 to the high-speed steel
Irradiated with keV nitrogen ions.

At this time, the ratio of boron atoms to nitrogen atoms (B / N) on the high-speed steel substrate 2 was adjusted to 1.5 to form a boron nitride thin film having a thickness of 1 μm.

The high-speed steel substrate 2 has a hardness HRC64 obtained by tempering SKH2 high-speed steel at a tempering temperature of 570 ° C.
It is a throw-away tip of TPP322 having:

Comparative Example 1 The amount of nitrogen ions implanted into the high-speed steel substrate 2 by the ion source 3 in the first step was set to 1 × 10 ¹⁷ / cm ² , and the other examples were the same as in Example 1.
A boron nitride thin film was formed on the high-speed steel substrate 2 through the same conditions and process as those described above.

Comparative Example 2 The injection rate of nitrogen ions into the high-speed steel substrate 2 by the ion source 3 in the first step was set to 1 × 10 ¹⁸ / cm ² , and the others were the same as those in Example 1.
A boron nitride thin film was formed on the high-speed steel substrate 2 through the same conditions and process as those described above.

Comparative Example 3 A boron nitride thin film was formed on a high-speed steel substrate 2 under the same conditions and processes as in Example 1 except that the first step was omitted.

Using the samples of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 thus manufactured, a cutting test was performed to evaluate the tool life, and the flank wear of each sample was measured.

The conditions of this cutting test were as follows: SCM415, hardness HCR
45 round bars, cutting speed 26.7m / min, feed 0.25mm / ve
v, depth of cut 2 mm, spindle speed 152 rpm, cutting length 100 m.

As a result of this cutting test, the flank wear of each sample was as follows.

The flank wear of the sample of Example 1 was 0.1 mm, the flank wear of the sample of Comparative Example 1 was 0.3 mm, the flank wear of the sample of Comparative Example 2 was 0.4 mm, and the flank of the sample of Comparative Example 3 Wear amount is 0.6mm
It became.

In the samples of Comparative Examples 1, 2 and 3, peeling of the boron nitride thin film was observed during cutting, whereas the boron nitride thin film of the sample of Example 1 did not peel during cutting. Was.

For comparison, when the above-mentioned cutting test was performed using a commercial product in which titanium nitride was coated on a high-speed steel substrate by the CVD method, the amount of relief friction was 0.25 mm.

As is evident from the results, the sample of Example 1 according to the method of the present invention is more excellent in abrasion resistance than the other comparative examples.

〔The invention's effect〕

The method for producing a high-speed steel cutting tool coated with a boron nitride thin film according to the present invention is characterized in that the second step of vapor deposition of a substance containing boron and irradiation of ion species containing nitrogen ions are used to nitride the surface of the high-speed steel substrate. As said process of forming a boron thin film, by implanting nitrogen ions into the surface of a high-speed steel substrate in a first step performed continuously using the same apparatus,
Since these nitrogen ions nitride the surface of the high-speed steel substrate,
The hardness of the surface of the high-speed steel substrate itself can be increased, and the affinity between the high-speed steel substrate and the boron nitride film containing c-BN formed in the second step can be increased. As a result, it is possible to significantly improve the adhesion between the high-speed steel substrate and the boron nitride thin film containing c-BN, and to produce a boron nitride thin film-coated high-speed steel cutting tool with extremely excellent cutting performance and tool life. Can be.

Further, by setting the nitrogen ion implantation energy in the first step within the range of 500 eV to 40 keV, damage to the high-speed steel substrate caused by the nitrogen ions can be reduced, and the temperature rise of the high-speed steel substrate can be suppressed. By setting the nitrogen ion implantation amount within the range of 1 × 10 ¹⁴ / cm ² to 1 × 10 ¹⁶ / cm ² , the hardness of the high-speed steel substrate itself due to nitriding of the surface of the high-speed steel substrate is reduced. Enhanced and high speed steel substrate and c
The effect of improving the affinity with the boron nitride thin film containing -BN can be greatly enhanced. As a result, the adhesion between the high-speed steel substrate and the boron nitride thin film can be remarkably improved, and a high-speed boron cutting tool coated with a boron nitride thin film having extremely excellent cutting performance and tool life can be manufactured.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a thin film forming apparatus used for carrying out the present invention. 2 ... High speed steel substrate, 3 ... Ion source, 4 ... Evaporation source

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-103368 (JP, A) JP-A-60-169559 (JP, A) JP-B-62-19503 (JP, B2) (58) Field (Int. Cl. ⁶ , DB name) C23C 14/00-14/58

Claims (1)

(57) [Claims] 1. A method for forming a boron nitride thin film by a single apparatus, wherein nitrogen ions are implanted at an energy of 500 eV.
4040 KeV and the nitrogen ion implantation amount is 1 × 1
The first step of implanting the high-speed steel substrate surface within the range of ¹⁴ / cm ² to 1 × 10 ¹⁶ / cm ² , the deposition of a substance containing boron, and the irradiation of ion species containing nitrogen ions are performed. The second to use together
And a step of forming a boron nitride thin film containing c-BN to form a boron nitride thin film-coated high-speed steel cutting tool.