JP3443314B2 - Coated hard tool - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated hard tool having a coating with excellent oxidation resistance and wear resistance.

[0002]

2. Description of the Related Art Conventionally, Ti has been used as a coated hard tool, especially as a film for a physical vapor deposition method represented by an ion plating method.
Films of N, TiCN, etc. were general and general,
In recent years, studies have been made to improve wear resistance and oxidation resistance by containing Al, and are disclosed in Japanese Patent Publication No. 4-53642 and Japanese Patent Publication No.
As described in Japanese Patent Publication No.-67705, there are various cases in which the effect of adding Al is recognized. In these cases, the addition of Al to the coating certainly improves the oxidation resistance and wear resistance of the coating. However, recently, the cutting speed tends to be further increased, and in many cases, high hardness steel after heat treatment is cut. In such a case, the cutting edge temperature of the tool becomes extremely high, and simply adding Al At present, it is not possible to obtain sufficient oxidation resistance to withstand use.

On the other hand, it has been proposed to coat the above carbides, nitrides, etc. with TiAlON or the like as the outermost layer in order to further improve the oxidation resistance thereof (for example, JP-A-7-32).
No. 8811), oxides of Ti and Al have not yet achieved sufficient oxidation resistance. A proposal has also been made to coat the outermost layer of alumina (for example, Japanese Patent Laid-Open No. 9-192906), but the alumina coating in the ion plating method has a weak adhesion itself and is easily peeled off, so that impact is not obtained in actual cutting. It peels off due to the force, and it is still not satisfactory.

[0004]

According to the research of the present inventors, in a TiAlN film in which Al is added to Ti,
The oxidation start temperature in the atmosphere is higher than 450 ° C of TiN, and is improved to 750 ° C to 900 ° C depending on the amount of Al added. However, in recent high-speed cutting, the cutting edge temperature often exceeds 900 ° C., and a sufficient cutting life cannot be obtained by simply adding Al.
Therefore, even in such high-speed cutting, in order to realize long-life and stable cutting, it is necessary to further increase the oxidation resistance of the coating.

[0005]

[Means for Solving the Problems] As a result of intensive studies conducted by the present inventors to improve the oxidation resistance of the coating, the results of the periodic table 4
By alternately laminating and coating a first layer of a compound of group a, 5a, 6a and Al, for example, a TiAlN layer and an AlO layer, the oxidation resistance of the TiAlN layer is significantly improved with respect to the oxidation resistance of the TiAlN layer. Came to confirm. Further, by coating the outermost layer with an AlO layer, the oxidation resistance is further improved, and by adding Si or a group 3a component to the first layer, the oxidation resistance of the first layer itself is improved. We have come to the knowledge that the oxidation resistance of the entire coating is further improved.

[0006]

In detail, when the TiAlN layer, which is said to have excellent oxidation resistance, is subjected to an oxidation test in the atmosphere, Al near the film surface diffuses to the outermost surface to form alumina. The formation of this alumina is the reason why the diffusion of oxygen into the inside of the film is suppressed and the oxidation resistance is improved. In this case, the film immediately below the alumina is a Ti oxide of rutile structure where Al does not exist as a result of Al diffusing to the outermost surface. It becomes a thing. This Ti oxide is very porous, and the alumina formed on the outermost surface functions as a barrier for oxygen diffusion in promoting static oxidation in the static oxidation test. Porous Ti
As a result of being easily peeled off from the oxide layer, the barrier effect is not sufficiently exerted against the promotion of oxidation, and the oxidation proceeds continuously.

When a second layer of AlO is interposed between the first layer of TiAlN to form a laminated structure, one of the first layers is oxidized as described above and a porous oxide layer of Ti is formed. The second layer of AlO forming the outermost layer functions as a barrier to oxygen diffusion even when peeled from the surface, so that oxidation of the coating is greatly suppressed during dynamic cutting, resulting in a stable length during cutting. Lifespan is achieved. Of course, AlO
The film also disappears due to peeling or abrasion during cutting, but since the underlying AlO film functions in the same way, the oxidation resistance of the entire film is greatly improved. Therefore,
By interposing as many second AlO layers as possible, preferably 10 or more layers, it is possible to achieve a sufficiently satisfactory cutting life. In addition, the second layer forms a continuity of the crystal structure with the first layer, so that the adhesiveness of the second layer is remarkably improved and peeling during cutting does not occur. That is, for example, when the first layer has an fcc structure, the second layer is an AlO layer having an fcc structure in which a superlattice is formed.

Further, by providing an AlO layer as the outermost layer, the oxidation resistance at the initial stage of cutting is improved and
The welding resistance to the work piece is also improved, and the life in cutting can be further extended. In this case, the outermost layer of AlO
When the layer has an amorphous crystal structure, the oxidation resistance is further improved. That is, since oxygen diffuses preferentially at grain boundaries, it is considered that the amorphous layer having no grain boundaries is more effective in suppressing the diffusion of oxygen and improving the oxidation resistance. Further, the outermost AlO layer has γ, κ, θ, α
Although such a crystalline material deteriorates the oxidation resistance to some extent, the AlO layer itself becomes hard and the wear resistance is improved. Therefore, it is preferable to select an amorphous layer or a crystal according to the cutting application. The crystal morphology of the AlO layer mainly depends on the coating temperature, and is amorphous, γ, θ, κ, α from the low temperature side.
It becomes a structure. Since the AlO layer is an insulating layer, it is preferable to use a pulse bias when it is desired to cover 100 nm or more in the ion plating method.

Further, as a result of attempting to add various third components in order to improve the oxidation resistance of the first coating, the oxidation resistance of the coating is improved by adding Y, Nd, Sm and Sc of Si and Group 3a metals. As a result, the property is remarkably improved. It has been clarified by the inventors of the present invention that these components segregate at the crystal grain boundaries of the first film and suppress the diffusion of oxygen at the grain boundaries to improve the oxidation resistance of the film.

Next, the reason for limiting the numerical values will be described. When the thickness of the AlO layer of the second layer when laminated is less than 1 nm, it has no effect on improving the oxidation resistance, and when it exceeds 50 nm, destruction occurs in the oxide layer, and as a result, the film may peel off. Therefore, it is set to 1 nm or more and 50 nm or less. If the substitution amount of the third component is less than 1 atomic%, there is no effect on improving the oxidation resistance.
If it is contained in excess of 0 atomic%, the wear resistance of the coating is deteriorated, so the content was made 1 to 30 atomic%.

[0011]

EXAMPLES The present invention will be described below based on examples. Example 1 A coated carbide end mill (8 mm in diameter, 6 blades) was manufactured by performing coating of the examples of the present invention and comparative examples under the conditions shown in Table 1 using a small arc ion plating device. The coating conditions were a bias voltage of −300 V and a reaction gas pressure of 4 × 10 ⁻² mb. Total film thickness is 2.
It was set to 5μ. Therefore, the total number of layers in the entire coating is different in each of the examples of the present invention. The AlO of the second layer and the outermost layer were formed by using an Al target and introducing oxygen gas intermittently. In Table 1, AlO whose crystal structure is not particularly described has an amorphous structure.

[0012]

[Table 1]

With the obtained end mill, the following cutting specifications were made:
Work material is SKD11 tempered material HRC60, cutting speed is 40 m / min, feed amount is 0.06 mm / blade, depth of cut is 12 mm x 0.8 mm, shoulder cutting, cutting test without using cutting oil (dry) I went. Cutting was performed until breakage occurred, and Table 1 also shows the cutting length at the time when breakage occurred.
Then, an oxidation test was performed in the atmosphere at 1000 ° C. for 30 minutes to measure the thickness of the oxide layer. The results are also shown in Table 1.

From Table 1, it can be seen that in the present invention in which the second layer (AlO layer) is provided in the laminated structure, the oxidation resistance of the coating is remarkably improved, and excellent characteristics are exhibited in the cutting of the hardened and hardened material. it is obvious. According to the measurement by the inventors,
It has been confirmed that the cutting edge temperature reaches 950 ° C. when HRC60 steel is cut under these conditions. Also, HRC
With steel No. 50, the cutting speed reaches 950 ° C. at a cutting speed of 120 m / min (other conditions are in accordance with the cutting conditions of Example 1). The examples of the present invention show excellent cutting characteristics under cutting conditions in which the cutting edge temperature exceeds 950 ° C regardless of the hardness of the material to be cut. Particularly in dry cutting, it brings an effective effect.

When the thickness of the oxide layer at 1000 ° C. is compared, it can be seen that in the case of a film made of TiN, TiAlN, etc., the oxide layer is oxidized to the total film thickness or almost the total film thickness. On the other hand, in the examples of the present invention, the TiAlN layer immediately below the outermost layer was not oxidized and showed excellent oxidation resistance. Further, as in Example 1 of the present invention, the thickness of the oxide layer stops at the third layer counted from the outside, which means that even after the outermost layer disappears due to wear, the progress of oxidation due to the intermediate AlO layer. Indicates that it can be stopped.

Example 2 Cemented carbide drills and cemented carbide inserts were coated with the same films of the present invention example and comparative example shown in Example 1, and a cutting test was conducted under the following conditions. With a wet drill, φ6
Work material SC using a mm (P40 grade) drill
M440 (annealed material), cutting speed is 100 m / min, feed rate is 0.1 mm / rev, hole depth of 15 mm is drilled, wear amount after 3000 hole cutting, insert shape is SEE42TN. (P40 grade), the work material SKD61 (tempered material HRC42,
Chamfer of width 100 mm x length 250 mm), cutting speed 1
50 m / min, feed amount 0.15 m / blade, depth of cut 1.
The flank wear amount after cutting 10 m at 5 mm was measured. The results are shown in Table 2.

[0017]

[Table 2]

As is clear from Table 2. It was confirmed that the examples of the present invention similarly show excellent tool life in drills and inserts. This tendency is the same for end mills, drills and inserts. In particular, with the wear of the tip blade that performs continuous cutting such as with a drill, the wear of the outer peripheral portion of the tip was small, and the number of drilled holes could be dramatically increased.

Example 3 Using a compact arc ion plating device, coating shown in Table 3 was carried out to produce a cemented carbide end mill and a cemented carbide insert coated with the examples of the present invention. The outermost crystallized AlO layer is 790 ° C. for α and 68 for γ.
The film was formed under the coating condition of 0 ° C. Cutting evaluation was performed on the inventive example and the comparative example under the cutting conditions shown in Example 1 and Example 2, and the results are also shown in Table 3. Further, an oxidation test was conducted under the conditions of 1000 ° C. for 2 hours in the atmosphere, and the thickness of the formed oxide layer is also shown in Table 3. Also in this embodiment, the total film thickness is 2.5 μm.

[0020]

[Table 3]

As shown in Table 3, the oxidation resistance of the multilayer film of the present invention was further extended from the time of Example 1 (30 minutes) by 1.5 hours to 2 hours, and the oxidation progressed further in the thickness direction. When the situation was confirmed, the influence of oxidation progressed from the outermost layer to the 6th to 10th first layers, it stopped in the second layer in the middle, and further, in sample numbers 15, 16, and 17. In the example, the oxide layer had a thickness of about 2 μm in 30 minutes, but reached the total thickness in 2 hours, so it is clear that it shows more excellent oxidation resistance and cutting life. Also in cutting, the cutting length can be greatly extended, and this tendency is particularly remarkable in the case of inserts. The inserts are often used in a dry type, and the cutting resistance is greater than that of end mills due to the blade type, and the thermal effect during cutting is great, resulting in a longer life. It is clear that the interposition of the oxide film further improves the oxidation resistance and the tool life.

Example 4 Using a TiAlX alloy target containing a predetermined amount of the third component X, a cemented carbide end mill coated with the example of the present invention shown in Table 4 was prepared, and the same cutting evaluation and example as in Example 1 were carried out. The same oxidation test as 3 was performed. The results are also shown in Table 4. In this case, the second layer is fcc AlO (5n
m) and the outermost layer is an amorphous AlO layer.

[0023]

[Table 4]

From Table 4, it is possible to further delay the progress of oxidation by improving the oxidation resistance of the first layer. Further, with the improvement of the oxidation resistance, the cutting life of the end mill is TiAlN. Single layer coating (Sample No. 15, 1)
Compared with 6, 17), the life is extended 3 to 4 times, and it is clear that the life is further improved.

[0025]

EFFECTS OF THE INVENTION By applying the present invention, the oxidation resistance and wear resistance of the conventionally used TiAlN film can be greatly improved. Especially, the oxidation start temperature in the atmosphere is TiAlN.
The N can be increased up to 1000 ° C with respect to 750 ° C to 900 ° C, and its progress in the thickness direction is also improved by the second layer. As a result, long-life and stable cutting can be realized especially in high-speed cutting and cutting of high hardness material.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-252306 (JP, A) JP-A-6-262407 (JP, A) JP-A-7-136810 (JP, A) JP-A-9- 291353 (JP, A) JP-A-7-97679 (JP, A) JP-A-7-133111 (JP, A) JP-A-8-209337 (JP, A) JP-A-8-199341 (JP, A) JP 2000-24809 (JP, A) JP 11-309606 (JP, A) JP 11-309607 (JP, A) JP 8-20871 (JP, A) JP 9-323204 ( JP, A) JP 9-295204 (JP, A) JP 11-42504 (JP, A) JP 11-90737 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 B23B 27/14 B23P 15/28

Claims (6)

(57) [Claims] 1. A coated hard tool comprising a hard coating layer coated by an ion plating method and made of a super hard alloy such as high speed steel, cemented carbide or cermet. The second layer is formed by alternately stacking 20 or more layers, and at least a part of the first layer is one of carbides, carbonitrides, and nitrides of 4a, 5a, and 6a of the periodic table and Al, or It consists of two or more kinds, and the second
The layer is an Al oxide layer, an oxynitride layer, or an oxycarbonitride layer.
The second layer has a thickness of 1 nm or more and 50 n or more.
A coated hard tool characterized by being m or less . 2. The coated hard tool according to claim 1, wherein
A coated hard tool characterized by being coated with an Al oxide layer, an oxynitride layer or an oxycarbonitride layer as the outermost layer. 3. The coated hard tool according to claim 2, wherein
A coated hard tool, wherein the outermost Al oxide layer, oxynitride layer, or oxycarbonitride layer has an amorphous crystal structure. 4. The coated hard tool according to claim 2, wherein
A coated hard tool, wherein the outermost Al oxide layer, oxynitride layer, or oxycarbonitride layer is crystalline. 5. The coated hard tool according to claim 1, wherein an Al oxide, oxynitride or oxycarbonitride layer which is a second layer to be laminated is continuous with the first layer and crystallinity. A coated hard tool characterized by having. 6. The coated hard tool according to claim 1, wherein a part of the components of the first layer is in the range of 1 to 30 atomic% and is one or more of Si, Y, Nd, Sm and Sc. A coated hard tool characterized by being replaced by.