JP2003301264A - Ti-Al ALLOY TARGET MATERIAL FOR FORMING SURFACE COATING ON CUTTING TOOL, MANUFACTURING METHOD THEREFOR, AND FILM-FORMING METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Ti-Al alloy target material for vacuum vapor deposition, particularly a Ti-Al alloy target material which imparts a film excellent abrasion resistance, oxidation resistance, agglutination resistance and adhesiveness, when used as a vapor deposition source for arc ion plating, and is optimal for forming a surface film on cutting tools, and to provide a manufacturing method therefor, and a film-forming method with the use of the target material. <P>SOLUTION: The Ti-Al alloy target material for forming the film on the cutting tools substantially consists of Al and Ti, includes 0.2-0.6 mass% oxygen, and has a ratio of Al to Ti, Al/Ti, in an amount of 0.4-1.9 by atom.%. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target material for vacuum vapor deposition for forming a surface coating of a cutting tool, and is particularly effective as an evaporation source for coating coating by arc ion plating. Ti-
The present invention relates to an Al alloy-based target material, a manufacturing method thereof, and a film coating method using the target material.

[0002]

2. Description of the Related Art A Ti-Al type hard coating such as a nitride film or carbonitride film is applied to the surface of a cutting tool or the like for the purpose of improving wear resistance and oxidation resistance. Ti-A
For the coating of 1-based hard coating, Ti-
It is optimal to use an Al alloy-based target material and perform film formation by the above-mentioned arc ion plating method.

The arc ion plating method, which is one of the ion plating methods, instantly melts and ionizes a target material, which is a raw material of the coating, by arc discharge in a depressurized reaction gas atmosphere and negatively applies it. It is a method of forming a film by adhering to a coating base material. At this time, the melted target material is ionized together with the reaction gas in the plasma generated between the coating base material and the target material. The arc ion plating method has a higher ionization rate of evaporated metal than the ion plating method using an electron gun, etc., so that a film with excellent adhesion can be obtained, so the amount of application is currently increasing. There is.

[0004] Generally, the Ti-Al hard coating is used as a nitride film using nitrogen as a reaction gas. As described in JP-A-8-3750 recently, for example, by simultaneously adding nitrogen and oxygen to a gas and interposing an oxide in a nitride film, the adhesion resistance of the film is further improved, and a cutting tool. It has been proposed that the performance of the etc. is improved.

[0005] The Ti-Al hard coating has a large residual compressive stress in the coating, and therefore has a drawback that the coating is easily peeled off when the coating base material is deformed.
The inclusion of an oxide in the coating reduces the residual compressive stress and improves the adhesion of the coating.

[0006]

As described above, when a conventional Ti--Al alloy-based target material is used, Ti--
In order to interpose an oxide in the Al-based hard coating, it is necessary to add a few% of oxygen to the reaction gas, but the reaction gas mixed with oxygen spreads throughout the heated furnace. Therefore, as the film forming work is repeated, the inner wall of the film forming apparatus vacuum container, which is originally required to be electrically conductive, and the surfaces of the electrodes and the like arranged in the apparatus are gradually covered with oxide as an insulating material. Will be covered by. As a result, the film forming apparatus cannot perform stable film formation, and the performance of the obtained film is significantly deteriorated. From this, it was difficult to say that the Ti-Al-based hard film having an oxide interposed therein can be sufficiently applied to mass production as an industrial product even though the film can be experimentally formed.

The present invention has been made in view of these circumstances, and is particularly suitable for a Ti-Al alloy-based target material for the surface of a cutting tool which requires adhesion resistance and adhesion, and a method for producing the same. And to establish an effective film coating method.

[0008]

The inventor of the present invention does not introduce a large amount of oxygen into a film forming atmosphere, but rather a Ti of a specific composition.
The present invention has been found out that excellent coating characteristics as a cutting tool can be obtained by setting the oxygen content of the —Al alloy-based target material itself to a specific value.

That is, the present invention consists essentially of Al and Ti, contains 0.2 to 0.6 mass% of oxygen, and has a composition ratio of Al and Ti of Al / Ti of 0.4 to 1 in atomic%. Ti- for forming a surface coating of a cutting tool, characterized in that
It is an Al alloy-based target material.

Ti-for forming a surface film of the cutting tool of the present invention
In the Al alloy-based target material, the target material structure has an area ratio of 20 intermetallic compound phases due to the target material constituent elements.
˜90%, a Ti—Al alloy-based target material in which any one or two of the Ti alloy phase in which the target material constituent elements other than Ti are solid-dissolved in Ti and the pure Ti phase constitute the balance More preferable.

The target material of the present invention is also preferable for arc ion plating.

According to the method of manufacturing the Ti-Al alloy-based target material of the present invention, the composition ratio of Al and Ti in atomic% is Al / T.
i: 0.4 to 1.9, oxygen content 0.2 to 0.6
It is to consolidate the mixed powder having a mass% by using a pressure sintering method. At this time, the intermetallic compound powder consisting of the target material constituent elements and the Ti powder were mixed at a predetermined ratio, and the mixed powder having an oxygen content of 0.2 to 0.6 mass% was prepared by a pressure sintering method. Any of an intermetallic compound phase composed of target material constituent elements in the structure by consolidation at a sintering temperature of 800 to 1200 ° C., a Ti alloy phase in which the target material constituent elements other than Ti are solid-dissolved in Ti, and a pure Ti phase It is more desirable to appropriately leave one or two kinds.

By utilizing these techniques, an effective coating method for the Ti-Al hard coating on the surface of the cutting tool has been established. That is, in the film coating method using the target material, oxygen is contained in an amount of 0.2 to 0.6 mass%, and the composition ratio of Al and Ti in atomic% is Al / Ti:
A Ti-Al alloy-based target material of 0.4 to 1.9,
Alternatively, the intermetallic compound phase of the target material constituent elements is 20 to 90% in area ratio, and any one or two kinds of the Ti alloy phase and the pure Ti phase in which the target material constituent elements other than Ti are solid-dissolved in Ti are substantially formed. The coating film coating method is characterized in that the cutting tool is coated by arc ion plating in a nitriding atmosphere with the Ti-Al alloy-based target material that constitutes the remaining balance.

[0014]

An important feature of the present invention is that the amount of oxygen added to a Ti--Al alloy-based target material is regulated within a specific range without adding a large amount of oxygen to the reaction gas. By containing an appropriate amount of oxygen in the target,
Most of the oxygen exists in the plasma generated between the coating base material and the target material together with the metal element of the target material and is ionized. Therefore, unlike the conventional case, oxygen does not spread throughout the heated furnace. As a result, the film forming apparatus can perform stable film formation. This not only exhibits stable film formation characteristics when applied to the arc ion plating method, but also provides excellent wear resistance, oxidation resistance, adhesion resistance, and adhesion when coated on a cutting tool. Can be given.

First, the oxygen content of the Ti--Al alloy target material of the present invention will be described. In a target material that is generally used under reduced pressure, it is considered that the smaller the oxygen content as an impurity component, the better. However, as a result of studies by the inventors, it was found that this is under a reduced pressure of 10 ⁻¹ Pa or less. The target pressure for sputtering that is used in, for ion plating for the purpose of coating a hard coating on a cutting tool, etc., because the working pressure is 10 ^-1 Pa or more, a certain range It was confirmed that there was no problem inside.

Oxygen in the target material causes an oxide to intervene in the film. As a result, although the coating hardness is slightly reduced, the chemical affinity of the coating to the metal is reduced.Therefore, when the coating and the metal that is the work material rub during cutting, the adhesion at the cutting edge of the cutting tool Such phenomena are suppressed and, as a result, the wear resistance of the coating is improved. In addition, the conventional Ti-Al hard coating has a large residual compressive stress in the coating, and thus has a drawback that the coating is easily peeled off when the coating base material is deformed. However, by applying the present invention, Residual compressive stress is relaxed by the oxide intervening in, and the adhesion of the film is also improved. In particular, in a cemented carbide coating end mill that performs high-speed dry cutting of high hardness materials of about 60 HRC, the cutting edge of the tool is deformed by cutting stress and heat generated during cutting even if the coating base material is cemented carbide. Therefore, the adhesion of the film is very important.

At this time, if the oxygen content in the target material is less than 0.2% by mass, the oxide is not sufficiently formed in the film, and the effect cannot be obtained. However, when the oxygen content exceeds 0.6%, the oxides dispersed in the target material become coarse, and abnormal discharge occurs during use, and the arc frequently misfires, making the discharge extremely unstable. .
As a result, the characteristics of the obtained coating are also deteriorated. In addition, the surface of the target material is consumed non-uniformly, and the life of the target material itself is extremely shortened. For the above reasons, the oxygen content is specified to be 0.2 to 0.6% by mass. More preferably, it is more than 0.3% and 0.5% or less.

The composition of the Ti—Al alloy target material of the present invention will be described. Al is Ti-obtained by a film forming method such as arc ion plating.
It is an element effective in improving the oxidation resistance and increasing the hardness of the Al-based hard coating, and the value of Al / Ti is important. Al
If / Ti is atomic% and is less than 0.4, the above effect cannot be obtained because the Al content is too small, and conversely, if it exceeds 1.9, the adhesive strength and hardness of the coating are significantly reduced. Therefore, the composition ratio of Al and Ti in atomic% is Al / Ti: 0.4.
~ 1.9. It is preferably 0.6 to 1.5.

In the Ti—Al alloy-based target material of the present invention, in the case of suppressing the droplet generation amount, the intermetallic compound phase due to the target material constituent elements is 20 to 9 in area ratio.
1% of Ti alloy phase and pure Ti phase in which the constituent elements of the target material except 0% and Ti are the solid solution in Ti
It is desirable that the species is two or two. Usually, when a Ti-Al alloy-based target material is manufactured by using powder as a raw material, pure Ti and pure Al powder are used, but the structure of the Ti-Al alloy-based target material manufactured by this is:
An Al phase having a low melting point and a Ti phase having a high melting point coexist. When this is applied to the arc ion plating method, the melting amount of the Al phase having a low melting point increases, which causes droplets. Therefore, in the case of suppressing the amount of generated droplets, the structure of the target material is composed of one or two of an intermetallic compound phase, a Ti alloy phase, and a pure Ti phase for the purpose of reducing the difference in melting point of each phase. It is desirable to do.

The intermetallic compound phase consisting of the constituent elements of the target material is mainly composed of one or more of the intermetallic compounds such as Ti ₃ Al, TiAl and TiAl ₃ , and the area ratio of these intermetallic compounds is 20 to 20 in the target material structure. 90
%, The balance substantially T is the target material constituent element except Ti.
When any one or two of the Ti alloy phase and the pure Ti phase solid-dissolved in i are contained, the amount of droplets generated is suppressed. When the area ratio of these intermetallic compound phases is less than 20%, the Al alloy phase is present in the structure in order to keep the Al content within the composition range of the present invention.
The above effect is not obtained, which is not desirable. On the other hand, if it exceeds 90%, the strength and toughness of the target material are insufficient, so that cracks or breaks occur during use, which causes abnormal discharge. Therefore, the intermetallic compound phase composed of the target material constituent elements is an area ratio of 20 to 90%, and the remainder is substantially any one of a Ti alloy phase and a pure Ti phase in which the target material constituent elements except Ti are solid-dissolved in Ti. Alternatively, it is desirable that the number is two. The intermetallic compound phase is preferably uniformly dispersed in the target material. A more preferable range is 25 to 85%.

The Ti-Al alloy-based target material of the present invention can be used for film formation by sputtering, but when it is used for a coating of a cutting tool, it is excellent in the adhesion of the coating, and therefore it is arc ion plating. It is most preferable to use. Sputtering is
Since it is used under a reduced pressure of 10 ⁻¹ Pa or less, oxygen generated from the target material is not easily contained in the coating, and also makes the glow discharge on the surface of the target material unstable. On the other hand, in arc ion plating, the working pressure is 10 ⁻¹ Pa or more, specifically several Pa.
Since the pressure is high with respect to sputtering, oxygen is likely to be contained in the film, and arc discharge for melting and evaporating the target material surface is less likely to become unstable. From this, the Ti-Al alloy-based target material of the present invention is most preferably used for arc ion plating.

In producing the Ti--Al alloy-based target material of the present invention, first, a mixed powder having an Al / Ti ratio of a predetermined ratio and containing 0.2 to 0.6 mass% of oxygen is pressure-fired. Consolidation is carried out using a binding method, for example, either the HIP method or the hot pressing method. As a raw material, oxygen is 0.2 to
By using a powder containing 0.6% by mass, the Ti-
It is possible to manufacture an Al alloy-based target material. At this time,
The pressure for consolidation is not particularly limited, but under the condition that the relative density is 98% or less, many defects such as micropores remain in the target material, and abnormal discharge during use of the target material. This is not preferable because problems such as the above may occur.

Further, for the purpose of suppressing the amount of generated droplets, an intermetallic compound powder consisting of target material constituent elements and a Ti powder are mixed in a predetermined ratio so that the oxygen content is 0.2 to 0.6 mass%. It is desirable to densify the mixed powder at 800 to 1200 ° C. by using a pressure sintering method such as a HIP method or a hot pressing method. The intermetallic compound powder consisting of the target material constituent elements to be used can be selected from intermetallic compounds such as Ti ₃ Al, TiAl, and TiAl ₃ depending on the required Al / Ti as required. At this time, if the consolidation temperature is lower than 800 ° C., the consolidation is not sufficient, so that many defects such as micropores remain in the target material and the bonding between the powders is insufficient, resulting in insufficient strength. On the other hand, if the temperature exceeds 1200 ° C. and is consolidated, the intermetallic compound phase composed of the elements forming the target material exceeds 90% in area ratio, and the target material becomes brittle. Therefore, the temperature for consolidation by the HIP method or hot pressing method is 800 to 1200 ° C.
Limited to

Further, using the Ti-Al alloy-based target material of the present invention, a Ti-Al-based hard material such as a nitride film or a carbonitride film is formed on a cutting tool by arc ion plating in a nitriding atmosphere or a carbonitriding atmosphere. By coating the film, it is possible to obtain a cutting tool having excellent adhesion resistance and adhesion.

The target material of the present invention is substantially T
i, Al, but if necessary IVa,
If necessary, a metal element of group Va or VIa and Si or B may be added in a trace amount of 30% or less, further 10% or less in atomic%. Further, as inevitable impurities, H, N, C
1, Fe can be mentioned, but these are H: 0.1
It is preferable that the content is not more than mass%, N: 0.05 mass% or less, Cl: 0.2 mass% or less, and Fe: 0.1 mass% or less.

[0026]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited to the following examples, and can be arbitrarily modified without departing from the scope of the present invention. Also included in the technical scope of the present invention.

Ti powder of 100 mesh or less,
After selecting variously from Al powder and TiAl ₃ powder and adjusting the atomic weight ratio (Al / Ti) of the target material shown in Table 1, respectively, after preparing a mixed powder with a V-type mixer and filling it into a steel container This was subjected to HIP treatment under the conditions shown in Table 1 for consolidation.

A block sample of 15 mm × 15 mm × thickness 10 mm for texture evaluation was machined from the obtained molded product, and φ100 mm × thickness 14 mm, bottom face was φ105 × thickness 2 mm for the purpose of investigating discharge characteristics and coating characteristics. The target material with the fixing collar was cut out. The amount of oxygen contained in each powder and target material is also shown in Table 1.
Shown in.

[0029]

[Table 1]

With respect to the block sample, the surface analysis of Ti and Al is carried out by an X-ray microanalyzer, the intermetallic compound phase consisting of the constituent elements of the target material is specified, and the area ratio thereof is calculated by image analysis. The metal phase constituting the target material was qualitatively determined by line diffraction. Here, the target material No. of the present invention. The SEM photograph of 11 is shown in FIG. The dark gray portion is the intermetallic compound phase, the white portion is the pure Ti phase, and the intermediate color portion is the Ti alloy phase.

On the other hand, the target material was mounted on a water-cooled cathode of an arc ion plating device, and a film was actually formed and evaluated. At this time, in order to evaluate the adhesion and the change in surface roughness due to the droplets, the coated surface (13 m
Cemented Carbide (JIS P4
0) material was used as the coating base material. A 6-blade end mill made of cemented carbide with an outer diameter of 8 mm was used to evaluate the practical properties of the coating. The coating condition is 1 × 1 at the beginning
After vacuuming to 0 ⁻³ Pa, heating to 500 ° C. and holding for 30 minutes, the pressure is set to 1.0 Pa in an Ar atmosphere, and the coating base material is cleaned at a Bias voltage of −400 V for 60 minutes with Ar ions. After performing, the pressure was 3.0 Pa in the N ₂ atmosphere, and the arc current of the target material was 100.
A, a Bias voltage of the coating base material: -100 V, and a nitride film was formed under the condition of 70 minutes.

The discharge characteristics of the target material were evaluated by the number of misfires of arc discharge on the target. Regarding the obtained coating, the state of peeling of the coating around the indentation was divided into four stages shown in FIG. 2 using a Rockwell C scale hardness tester, and the adhesion of the coating was evaluated. The surface roughness Ry (JIS-B-0601: maximum height) was used to evaluate the droplets on the coated surface with a measuring machine.
When the amount of droplets increases or when coarse droplets occur, Ry increases because the unevenness of the coating surface increases. Furthermore, for the evaluation of the practical properties of the coating, the cutting performance is evaluated under the dry high-speed cutting conditions shown below, and the cutting is continued until the tool becomes uncutable due to chipping or wear of the cutting edge. The tool life was evaluated. Table 2 shows the structure of the target material, the usage state of the target material, and the evaluation result of the film.

(Cutting conditions) Tool: Carbide 6-Flute End Mill Outer Diameter 8 mm Cutting method: Side cutting down cut, air blow Work Material: SKD11 (Hardness 60HRC) Notch: Ad 12mm × Rd 0.2mm Cutting speed: 150m / min Feed: 0.05mm / tooth

[0034]

[Table 2]

As is clear from Table 2, the comparative products whose oxygen content and Al / Ti are out of the range of the present invention are inferior to the products of the present invention in their usage conditions and film properties. In particular, a marked difference in tool life can be seen. Comparative product N
o. Reference numeral 27 is a target material equivalent to the conventional product, and although the conventional product has a relatively long tool life, it has a low oxygen content, and therefore does not reach the tool life of the product of the present invention. FIG. 3 shows the product No. No. 8 photoelectron spectroscopy apparatus for Ti-Al nitride film (XPS, X-ray Photoelectron)
It is the result of measurement by n Spectrometer), and in addition to the peak showing the bond between Ti and N, a peak showing the bond between Ti and O is also observed, which shows that an oxide is also present in the film. Further, among the products of the present invention, those in which the area ratio of the intermetallic compound phase and the structure constituting the target are within the desirable range of the present invention not only have excellent tool life, but also have a small surface roughness Ry, so that the hard coating It can be applied to a cutting tool for precision finishing in which smoothness is required on the surface after coating.

[0036]

As described above, the Ti-Al alloy-based target material of the present invention can regulate the oxygen addition amount of the target material without adding oxygen harmful to the apparatus to the reaction gas. Thus, it becomes possible to stably obtain a Ti—Al-based hard film in which an oxide intervenes. This allows
When coated on a cutting tool, it can be provided with excellent wear resistance, oxidation resistance, adhesion resistance, and adhesion, and can be supplied as a target material most suitable for surface coating.

[Brief description of drawings]

FIG. 1 is a SEM micrograph showing an example of a Ti—Al alloy-based target material of the present invention.

FIG. 2 is a diagram showing superiority and inferiority of adhesion of a film around an indentation when using a Rockwell C scale hardness tester.

FIG. 3 is a diagram showing a measurement result by a photoelectron spectrometer of an example of a Ti—Al nitride film obtained from a Ti—Al alloy-based target material of the present invention.

Claims (7)

[Claims] 1. It consists essentially of Al and Ti, contains 0.2 to 0.6 mass% of oxygen, and has a composition ratio of Al and Ti of Al / Ti: 0.4 to 1.9 in atomic%. A Ti-Al alloy-based target material for forming a surface film of a cutting tool, which is characterized by being present. 2. The target material structure has an area ratio of 20 to 90% of the intermetallic compound phase due to the constituent elements of the target material, and T
2. The cutting according to claim 1, wherein any one or two of a Ti alloy phase and a pure Ti phase in which the target material constituent elements except i are solid-dissolved in Ti substantially constitutes the balance. Ti-Al alloy-based target material for surface coating of tools. 3. The Ti—Al alloy-based target material for forming a surface coating of a cutting tool according to claim 1, wherein the target material is for arc ion plating. 4. The composition ratio of Al and Ti in atomic% is Al /
Ti: 0.4 to 1.9, oxygen content 0.2 to 0.
A Ti-for forming a surface film of a cutting tool, characterized in that a mixed powder of 6 mass% is consolidated by a pressure sintering method.
A method for manufacturing an Al alloy-based target material. 5. An intermetallic compound powder consisting of target material constituent elements and a Ti powder are mixed at a predetermined ratio, and a mixed powder having an oxygen content of 0.2 to 0.6 mass% is subjected to a pressure sintering method. Any one of an intermetallic compound phase composed of a target material constituent element in the structure and a Ti alloy phase and a pure Ti phase in which the target material constituent elements other than Ti are solid-solved in Ti. Alternatively, a method for producing a Ti—Al alloy-based target material for forming a surface coating of a cutting tool, characterized in that two kinds are left. 6. The method for producing a Ti—Al alloy-based target material for forming a surface coating of a cutting tool according to claim 4, wherein the target material is for arc ion plating. 7. A coating method for coating a cutting tool by arc ion plating in a nitriding atmosphere using the Ti—Al alloy-based target material according to claim 1 or 2 as a target.