JP2840541B2 - Hard coating, hard coating tool and hard coating member excellent in wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention requires a surface coating material of a cutting tool used for machining such as milling, cutting, and drilling, or high hardness such as a mold, a bearing, a die, and a roll. A hard coating useful as a surface coating material for wear-resistant members, or a surface coating material for heat-resistant and corrosion-resistant members such as screws and cylinders for molding machines, and a hard coating that exhibits excellent wear resistance by coating the hard coating. The present invention relates to a coating tool and a hard coating member.

[0002]

2. Description of the Related Art Cutting tools requiring high wear resistance, such as high-speed tools and cemented carbide tools, use TiN
By forming a hard coating such as Ti and TiC, wear resistance is improved. Comparing the abrasion resistance of TiN and TiC, TiN has a T
It is superior to iC and exhibits wear resistance against crater wear on the tool rake face caused by processing heat or frictional heat during cutting. Moreover, TiN has excellent adhesion to the base material. On the other hand, TiC has a higher hardness than TiN and has high durability against flank wear on the flank in contact with the work material. However, even with TiN having excellent oxidation resistance, the oxidation initiation temperature is about 600 ° C., and even with TiC having high hardness, its Vickers hardness is about 2000, and further improvement in wear resistance is required. Was desired.

For example, Japanese Patent Application Laid-Open No. 2-194159 discloses a composite nitride or composite carbonitride of Al or Ti in which part of Ti is replaced with Al for the purpose of improving the oxidation resistance and hardness of TiN or TiC. It has been disclosed that a hard coating exhibiting characteristics of an oxidation start temperature of about 800 ° C. and a Vickers hardness of about 2500 kg / mm ² has been developed.

Japanese Patent Application Laid-Open No. Hei 4-26756 discloses AlTiN.
(Al, Ti) (B, N) has been proposed in which the hardness is increased by adding B while taking advantage of the oxidation resistance of Vickers, and the Vickers hardness is improved to a maximum of about 3400 kg / mm ² . The oxidation start temperature is also about 800 ° C. Therefore, in fields such as cutting where higher efficiency is required, development of a hard coating having more excellent wear resistance has been expected.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it has been found that (Al, Ti) (B,
N) It is an object of the present invention to provide a hard coating which is more excellent in oxidation resistance and has high hardness and exhibits excellent wear resistance.

[0006]

The hard coating excellent in abrasion resistance according to the present invention, which can achieve the above object, is a coating formed on the surface of a base material, and comprises (Al _x Ti _1-xy Si _y ) (B _z N _1-z ) However, it is necessary to have a chemical composition represented by 0.05 ≦ x ≦ 0.75 0.01 ≦ y ≦ 0.1 0.01 ≦ z ≦ 0.12 It is assumed that.

The thickness of the hard coating is 0.1 to 20 μm.
It is preferable to form the hard coating on the surface of the base material by an arc discharge ion plating method, whereby a hard coating tool and a hard coating member excellent in wear resistance can be obtained.

[0008]

The present inventors have searched for additional elements effective in improving the wear resistance of the alloy for the purpose of further improving the wear resistance of (Al, Ti) (B, N). )
It has been found that boron / nitride containing a small amount of Si in (B, N) has a high hardness and a high oxidation initiation temperature, and the composition of the hard coating is (Al _x Ti _1-xy Si _y ) (B _z N _1-z )
In the chemical formula represented by 0.05 ≦ x ≦ 0.75
When 0.01 ≦ y ≦ 0.1 and 0.01 ≦ z ≦ 0.12 are satisfied, it is determined that a hard film having high hardness and good oxidation resistance and excellent wear resistance are exhibited. Completed the invention.

Further, since the hard coating according to the present invention does not impair the excellent substrate adhesion of TiN, there is a problem of peeling when applied to the surface of a substrate such as a mold, a tool or a wear-resistant member. Thus, it is possible to obtain a hard film-coated tool and a hard film-coated member that sufficiently exhibit the wear resistance of the film.

Although the reason why the hard coating of the present invention exhibits excellent wear resistance as compared with the conventional coating has not been fully elucidated, the inclusion of Si as the third metal element allows the hard coating to be used at high temperatures. This is considered to be because oxidation of Ti which occurs is suppressed and a protective film made of Al oxide is remarkably densified.

The composition of the metal element constituting the hard coating of the present invention is such that x and y in (Al _x Ti _{1 -xy} Si _y ) are 0.05 ≦ x ≦ 0.75 and 0.01 ≦ y ≦ 0, respectively. .1 must be satisfied. If the value of x is 0.0
If the value is less than 5 or the value of y is less than 0.01, a sufficient effect of improving oxidation resistance cannot be obtained. If the value of x exceeds 0.75 or the value of y exceeds 0.1, the crystal structure of the film changes from cubic to hexagonal, and the film hardness decreases and sufficient wear resistance is obtained. I can not get the nature.
The lower limit of x is preferably 0.25, and 0.5
More preferably, it is 6 or more. The upper limit of x is preferably 0.75, and more preferably 0.7 or less. The lower limit of y is preferably 0.01, and 0.0
More preferably, it is 2 or more. The upper limit of y is preferably 0.08, and more preferably 0.05 or less.

In the case of the boron nitride according to the present invention, B _z
It is necessary to satisfy 0.01 ≦ z ≦ 0.12 in N _1-z , and when the value of z is less than 0.01, the effect of improving the hardness by adding boron is not sufficiently exhibited. If it exceeds 12, the crystal structure composed of the NaCl structure becomes partially amorphous, and the hardness is rather lowered, which is not desirable. Z
Is more preferably 0.02, and more preferably 0.08.

The thickness of the hard coating when coated on a substrate is preferably 0.1 μm or more and 20 μm or less. If it is less than 0.1 μm, the wear resistance cannot be sufficiently exhibited, while if it exceeds 20 μm, cracks may be formed in the hard coating due to impact force, which is not desirable. When applied to a cutting tool, the thickness of the hard film is preferably 1 μm or more, more preferably 2 μm or more, and the upper limit, in order to take advantage of the characteristics of the original cutting edge of the tool base material and to obtain excellent wear resistance. 12 μm or less, more preferably 8 μm
The following is desired. Further, the present invention does not limit the material of the substrate on which the hard film is formed. However, in order to coat the substrate surface with good adhesion and exhibit excellent wear resistance, a cemented carbide or high-speed tool steel is required. Hard materials such as die steel, cermet, and ceramic are suitable.

As a method of forming the hard coating according to the present invention on the surface of a substrate, there is a PVD method typified by an ion plating method or a sputtering method. For example, an arc discharge type ion plating method is employed. In that case, the method exemplified below may be used. That is, A ionized from the cathode, which is the evaporation source, by arc discharge
l, Ti and Si metal components and B can be obtained by ion plating in an N ₂ atmosphere or an N ₂ -Ar atmosphere, and if a target having the same metal composition as the intended coating composition is used, A film having a stable composition is easily obtained. It is preferable to apply a bias potential to the substrate because the adhesion of the film can be further increased. In the present invention, the gas pressure at the time of ion plating is not particularly limited, but 1 × 10 ^{−3 to} 5 × 10 ^−2.
Torr is preferable, and within this range, it is easy to obtain a dense hard film having higher wear resistance and higher crystallinity.

Embodiments will be described below. However, the present invention is not limited to the following embodiments, and any appropriate changes in the spirit of the preceding and following embodiments are included in the technical scope of the present invention.

[0016]

【Example】Example 1 In order to check the oxidation resistance of the film, a 7 mm x 25 mm
Arc discharge type ion plating
And heated to 400 ° C.
The metal element is evaporated from the cathode having the composition
N as reactive gas _Two 7 × 10 by introducing gas^-3Torr
Make the atmosphere and apply a potential of -150V to the substrate.
The coatings of various compositions shown in Table 1 were formed to a thickness of 5 μm.
Specimens coated with were prepared.

The composition of the film was determined by electron probe X-ray microanalysis and Auger electron spectroscopy, and an oxidation test was performed under the following conditions. The results are shown in Table 1. (Oxidation test conditions) Temperature range: room temperature to 1300 ° C Temperature rising rate: 10 ° C / min Atmosphere: dry air, atmospheric pressure Air flow rate: 150 cc / min

[0018]

[Table 1]

As is apparent from Table 1, (A)
The l, Ti) (B, N) coating (No. 1) starts oxidizing at 810 ° C., whereas the hard coating (No. 3) according to the present invention.
Each of the oxidation start temperatures of 〜5) is 890 ° C. or higher,
Oxidation resistance is improved. No. 2 is a comparative example in which the amount of Si is small, and the oxidation start temperature is low, and no improvement in oxidation resistance is observed.

Example 2 A test piece was prepared in the same manner as in Example 1 except that a carbide tip was used as a substrate and the thickness of the film was 10 μm.
When the micro Vickers hardness of the film formed on the test piece was measured under a load of 100 g, the results shown in Table 1 were obtained.

As apparent from Table 1, the coatings (Nos. 3 to 5) according to the present invention are conventional examples (Al, Ti) (B,
N) shows higher hardness as compared with the coating (No. 1). On the other hand, No. No. 6 is a comparative example in which the amount of Si is too large, and since the crystal structure of the film changes from cubic to hexagonal, the film hardness is significantly reduced.

Example 3 A two-blade end mill having an outer diameter of 10 mm was manufactured using a cemented carbide as a base material, and a hard coating having a composition shown in Table 2 was formed on the blade surface of each end mill to a thickness of 4 μm. As a method for forming a hard coating, For only Sample No. 2, an ion plating method using a crucible deposition method was used, and the other hard films were formed by an ion plating method using an arc discharge method. Regarding the film formation conditions of the arc discharge method, the substrate temperature was 400 ° C., the bias voltage was −150 V, and the reaction gas was formed at 7 × 10 ⁻³ Torr.

Using the obtained hard film-coated end mill, a cutting test was carried out under the following conditions, and the wear amount of the flank of the end mill cutting edge was measured. The results are shown in Table 2 and FIG. (Cutting conditions) Cutting method: Side cutting down cut Work material: SKD11 (hardness HB219) Depth of cut: Rd 1 mm x Ad 10 mm Cutting speed: 60 m / min Feed: 0.07 mm / tooth (270 mm / m)
in) Cutting oil: Air blow Cutting length: 20m

[0024]

[Table 2]

As is clear from the results shown in Table 2, the hard film-coated end mills (Nos. 3 to 5) according to the present invention have less flank wear than the conventional examples (Nos. 1 and 2). Excellent wear resistance to abrasion. No. 6 is S
This is a comparative example in which the i amount is too large, the flank wear amount is large, and the wear resistance is not sufficient.

Example 4 A JIS standard drill having an outer diameter of 10 mm was prepared using a high speed tool steel equivalent to JIS standard SKH51 as a base material, and a hard coating having a composition shown in Table 3 was formed on the surface of the drill blade in the same manner as in Example 3. Was formed.

Using the obtained hard film-coated drill, a cutting test was performed under the following conditions, and the cutting life was examined. The results are shown in Table 3. (Cutting conditions) Cutting method: Drilling, 5 cutting each Work material: S55C (hardness HB220) Cutting speed: 30 m / min Feed: 0.15 mm / rev Cutting length: 30 mm (through hole) Cutting oil: Water-soluble emulsion type cutting oil

[0028]

[Table 3]

As is clear from the results in Table 3, the hard film-coated drills (Nos. 3 to 5) according to the present invention have a larger average number of drilled holes compared to the conventional examples (Nos. 1 and 2). Long service life. No. No. 6 is a comparative example in the case where the amount of Si is too large, the number of drilled holes is small, and the cutting life is short.

[0030]

The present invention is constituted as described above, and is a hard material exhibiting excellent wear resistance and oxidation resistance as compared with the conventional TiN film or (Ti, Al) (B, N) film. A film is obtained, and a high-hardness member exhibiting excellent wear resistance and oxidation resistance can be provided by coating the surface of the member with the hard film.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-194159 (JP, A) JP-A-4-26756 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 14/00-14/58

Claims (4)

(57) [Claims] 1. A film formed on a surface of a base material, A hard coating having excellent wear resistance, characterized by having a chemical composition represented by the following formula: 2. The hard coating according to claim 1, wherein the thickness of the coating is 0.1 to 20 μm. 3. A tool having a hard coating excellent in wear resistance, wherein the hard coating according to claim 1 or 2 is formed on the surface of a substrate by an arc discharge ion plating method. (4) The hard coating according to claim 1 or 2,
Discharge on the substrate surface by ion plating
Hard leather with excellent wear resistance characterized by being formed
Membrane-coated members.