JP2003165003A - Hard film coated member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extremely improve adhesion property, and to improve all characteristics of abrasion resistance, oxidation resistance, and lubricity without degrading any of them, and achieving stable long service life even in heavy cutting. <P>SOLUTION: In a hard film coated member coated with a hard film, the hard film contains Al, Ti, Cr, N, and O. When composition of respective elements is AlaTibCrcNwO1-w, 30≤a≤70, 30≤b≤70, 0.5≤c≤20, a+b+c=100, 0.7≤w≤0.99. A half-value width of diffraction peak of (200) face in X-ray diffraction in 2θ lies between 0.4 and 0.7 degrees. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear resistant member having excellent solid lubricity, high wear resistance and oxidation resistance, and excellent adhesion.

[0002]

2. Description of the Related Art It has become common to coat various hard coatings on tools, molds and machine parts in order to impart wear resistance, oxidation resistance and lubricity. Typical TiN,
Although the TiCN coating has excellent wear resistance, it has a problem in oxidation resistance. Further, the TiAlN-based coating has excellent wear resistance and oxidation resistance (for example, Japanese Patent Application Laid-Open No. 7-31017).
No. 3), the lubricity is low. CrN and CrCN type coatings have excellent lubricity, but have low coating hardness and poor wear resistance.
As described above, the conventional coating is inferior in wear resistance, oxidation resistance, and lubricity, and the present situation is that it has some problems in each application. Although a proposal has been made to coat the surface of the hard coating with a MoS-based coating having excellent lubricity in order to impart lubricity, this coating itself has poor adhesion and it has not been possible to obtain sufficient results. Further, in conventional coatings, the adhesion of the coating as a whole is still insufficient, and peeling of the coating occurs in heavy cutting, and stable cutting has not been realized.

[0003]

As described above, there are some problems in the conventional film, and in order to solve them, Mo is required.
In addition to the S type, it has been proposed to coat a CrN type coating on the upper layer of the TiAlN type coating as shown in Japanese Patent Application Laid-Open No. 11-156992, but since the total thickness is limited to some extent, abrasion resistance Is not completely satisfactory in terms of. The present invention is extremely excellent in adhesion, wear resistance,
The object of the present invention is to improve any of these properties without deteriorating either the oxidation resistance or the lubricity and achieve a stable long life even in heavy cutting.

[0004]

In order to achieve the above object, the present invention employs a hard coating in which Ti, Al, Cr and N are essential components and oxygen is added to them. Furthermore, by optimizing the film formation rate of the film, it has extremely excellent adhesion. In terms of composition, naturally Ti and Al contribute as wear-resistant components, and Cr contributes as a component that imparts lubricity. This results in imparting chemical conversion properties and lubricity. Further, in order to improve the adhesion and wear resistance, by optimizing the film formation rate, continuous growth of the crystal lattice of the WC particles contained in the substrate and the film, that is, so-called epitaxial growth is made possible. It has extremely excellent adhesion to the material and achieves more stable long-life cutting even in heavy cutting.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION First, in the study of the coating composition, based on TiAlN, and the effect of adding Cr to this is, firstly, further improvement in the oxidation resistance of the cutting tool. In the case of TiAlN, it is a well-known fact that Al diffuses to the surface inside the film due to oxidation and forms an oxide of Al, thereby suppressing the intrusion of oxygen from the outside and improving the oxidation resistance. However, in this case, since a very porous Ti oxide is formed immediately below the Al oxide, the Al oxide easily falls off when a shock is applied to a cutting tool or the like. , It is difficult to exert the effect continuously. The same applies to molds and the like. It has been clarified that the porous Ti oxide formed immediately below the Al oxide by the addition of Cr becomes a TiCr oxide, and this oxide forms a very dense layer. Therefore, the Al oxide formed on the outermost layer maintains the adhesiveness, and as a result, the oxidation resistance is improved.

The second effect of Cr addition is to give the TiAlN coating the excellent lubricity of Cr itself. The friction coefficient of TiAlN with steel is 0.7-0.8, but it improves to 0.3-0.6 with the addition of Cr.
This friction coefficient depends on the amount of Cr added. However, if the addition amount of Cr is too large, the film hardness decreases and the wear resistance deteriorates. Therefore, it is preferable to set the upper limit of the addition amount.

Even if only Cr is added, as described above, TiAlN
Although the effect of improving the lubricity and oxidation resistance of the system film is confirmed, Cr alone is not sufficient, and further improvement is recognized by adding oxygen to this. With respect to the effect of adding oxygen, the first is a dramatic improvement in oxidation resistance and a dramatic improvement in lubricity. In order to dramatically improve the oxidation resistance, by adding oxygen to the inside of the film, the crystal of the film becomes finer and the film itself becomes dense, and at the same time the crystal grain boundaries become dense, It is considered that the reason is that the oxygen diffusion rate with respect to the infiltration of oxygen is significantly suppressed. Although the lubricity has not been fully clarified, it is considered that the reason is that the affinity with steel decreases due to the addition of oxygen.

The second effect of oxygen addition is that the residual compressive stress of the coating is reduced and the adhesion of the coating is improved, resulting in improved wear resistance. In particular, under heavy cutting conditions and in the field of forging dies, the adhesion of the coating is a very important factor. Abrasion tends to progress due to minute peeling of the coating, and if a large amount of peeling occurs, the life becomes sudden. T
The peeling critical load of the iAlCrN-based film by the scratch test is 60-80N, while the strength is improved to 100N or more by adding oxygen.

However, as the amount of oxygen added increases,
Although the wear resistance resulting from the above-mentioned oxidation resistance, lubricity, and adhesion improvement is improved, on the other hand, the coating hardness itself is softened, resulting in deterioration of the abrasive wear resistance. Therefore, an optimum composition layer for contributing to oxidation resistance and lubricity,
It is more preferred to have multiple layers of optimal composition layers that contribute to abrasive wear, which results in a combination of both advantages. Multilayering is not only the difference in oxygen content,
The lubricity and wear resistance can be adjusted even when the layers having different Cr contents are formed in multiple layers.

However, in the so-called heavy cutting field where extremely high impact is generated, improvement in these compositional aspects may not be sufficient in adhesion, and may not realize sufficiently stable cutting. As a result of earnestly researching this problem in particular, the present inventors have confirmed the fact that the deposition rate of the coating has a great influence on the adhesion. It is desirable that the film formation rate be as slow as possible. According to the observation result of the present inventor, it was confirmed by transmission electron microscope observation that the film grows epitaxially with respect to the WC particles contained in the base material as the film formation rate becomes slower. As a result, the WC particles contained in the substrate and the film were bonded by Van den Waals force, resulting in extremely strong theoretically the best adhesion.

From the viewpoint of crystal structure, ordinary columnar crystals are excellent in abrasion resistance, but finer columnar crystals or so-called block crystals in which fine columnar crystals are divided in the longitudinal direction exhibit more preferable abrasion resistance. To do. In addition, the crystal grain size in the depth direction of the film can be controlled by adjusting the film formation temperature according to the film formation time, and the lower the temperature along with the film formation time, the finer the film becomes as it gets closer to the surface of the film. It is possible. As mentioned above, it is possible to improve wear resistance by refining the entire film, but since the residual compressive stress of the entire film tends to increase somewhat, such a surface side It can be said that finer means is more preferable microstructure control from the viewpoint of increasing the residual stress, that is, imparting wear resistance while suppressing deterioration of adhesion. In particular, when the outermost surface is formed into an amorphous form instead of columnar crystals, the wear resistance is significantly improved and the oxidation resistance can be greatly improved. This is because the grain boundaries are dense and oxygen is difficult to diffuse, so that the progress of oxidation is suppressed.

Next, the reason for limiting the numerical values will be described. The film formation rate had a correlation with the full width at half maximum of the film, and the slower the film formation speed, the smaller the full width at half maximum of the film. In order to achieve the above-mentioned epitaxial growth sufficiently, the film formation rate is in the range of 0.1 μm / hr to 0.8 μm / hr, and the corresponding (200) plane half width is 2θ.
Corresponds to 0.4 to 0.7 degrees. 0.8 μm / hr
When the film forming rate is exceeded, the 2θ value exceeds 0.7 degrees, the probability of epitaxial growth is low, and the adhesion is insufficient.
At an extremely low deposition rate of less than 0.4 degrees, it takes one day or more to obtain a film having a predetermined thickness, resulting in a problem from the viewpoint of economy and practicality.

Here, from 0.1 μm / hr to 0.8 μm
Even if the film forming rate is in the range of / hr, it is not sufficient from the viewpoint of economy and practicality. Therefore, the film is formed at the film forming rate in this range at the beginning of film formation, and the substrate WC is epitaxially grown. It can be said that increasing the film formation rate stepwise or stepwise is the most preferable method for solving the economical problem while maintaining the extremely excellent adhesion.

In terms of composition, if Al is less than 30 atomic%, the oxidation resistance of the coating deteriorates, and if it exceeds 70 atomic%, AlN having an hcp structure is formed in the coating and the coating strength deteriorates, which is not preferable. . If Ti is less than 30 atomic%, the wear resistance of the coating deteriorates, and if it exceeds 70 atomic%, the oxidation resistance of the coating deteriorates, which is not preferable. If Cr is less than 0.5 atom%, a porous Ti oxide is formed and does not contribute to the improvement of oxidation resistance, and if it exceeds 20 atom%, the hardness of the film is softened and wear resistance is deteriorated, which is not preferable. If oxygen is less than 1 atomic% with respect to nitrogen, it does not contribute to the improvement of oxidation resistance, lubricity and adhesion, and if it exceeds 30 atomic%, the film hardness is softened, which is not preferable.

The number of coatings in terms of the number of layers is sufficient even if it is a single layer, but by forming two or more layers, a combined effect of layers having various properties is recognized and more excellent performance is exhibited. When the number of layers exceeds 1000, the thickness of each layer becomes thin, sometimes forming a superlattice, and the residual stress becomes high.
It is not preferable because the adhesion is impaired. The film thickness of each layer is the same, and if the thickness is less than 5 nm, the residual stress becomes high,
When it exceeds 00 nm, the performance is similar to that of a single layer.

The crystal orientation of the film depends on the coating conditions. When the film is formed with a relatively low energy, it has a strong orientation on the (200) plane, and when it is formed with a high energy, it tends to the (111) plane. It was confirmed that when the film was formed with low energy, the film formation rate was slower, but the film density was improved, and the results were excellent in oxidation resistance and abrasion resistance. Therefore, when the (200) plane diffraction intensity is stronger than the (111) plane diffraction intensity, it is considered to be more preferable because it exhibits further excellent oxidation resistance and abrasion resistance. The crystal orientation did not have a great influence on the lubricity. However, the diffraction intensity of the (200) plane is 2 of the diffraction intensity of (111).
At low energy exceeding 0 times, the adhesiveness tends to deteriorate.

The compressive stress remaining in the film mainly depends on the coating conditions, but if it exceeds 3.5 Gpa, the adhesiveness deteriorates, which is not preferable. The coating of the present invention has the same tendency regardless of whether it is an arc ion plating method, a sputtering method, an electron gun evaporation method or a plasma assisted CVD method, or a combination of these methods may be used. Hereinafter, preferred examples of the present invention will be described together with comparative examples.

[0018]

EXAMPLES Coatings of Examples 1 to 27 of the present invention and Comparative Examples 28 to 43 were prepared by the arc ion plating method.
Table 1 shows the composition, structure, number of layers, and the like. The thickness of the film is 3000 nm to 3 in all the examples of the present invention and comparative examples.
It was unified at 200 nm.

[0019]

[Table 1]

The composition of AlTiCr of the present invention was adjusted by adjusting the metal composition of the cathode target which is the evaporation source. The oxygen content is adjusted by using a mixed gas of nitrogen and oxygen and adjusting the mixing ratio thereof,
The gas was changed to form multiple layers. Multiple layers of different metal component hard films were formed by installing cathode targets having different compositions. In terms of crystal orientation, basically adjust the coating conditions,
The (200) oriented film has a bias voltage of 70 V and a reaction pressure of 1 Pa for applying the coating conditions to the substrate, and the (111) oriented film has a bias voltage of 200 V and a reaction pressure of 0.5 Pa.
It was created by I (200) / I (11
1) The ratio is somewhat dependent on the film composition and oxygen content. In controlling the texture, the coating temperature is 450 ° C., 2 Pa to obtain normal columnar crystals, 400 ° C. and 2 Pa to obtain fine columnar crystals, 400 ° C. to obtain block-like crystals,
0.5 Pa, 350 ° C. for obtaining an amorphous state, 0.5 Pa
And coating conditions were controlled. The residual stress was adjusted by selecting the bias voltage within the range of 20 V to 250 V at a coating temperature of 450 ° C. and a reaction pressure of 2 Pa to change the stress. Further, in the present invention example, the arc current for evaporating the cathode target is as low as 50 to 70 A, and the film forming rate is generally 0.2 to 0.7 μ / h.
It was adjusted to be r. In Examples 16 and 17 of the present invention, the film formation rate was low in the first half and the arc current value was 120 A in the second half, and the coating was performed at a relatively high film formation rate of 1.7 μ / hr.
The adjustment of the full width at half maximum was performed by adjusting the arc current value, but it slightly changes depending on other coating conditions. In the comparative examples, the coating temperature is 450 ° C and the reaction pressure is 2P.
a, bias voltage 40 to 100 V, arc current 100 A
Was coated under the general conditions of.

Table 2 shows the measurement results of the film hardness and the like and the X-ray diffraction results which should contribute to the oxidation resistance, lubricity and wear resistance of the examples of the present invention and the comparative examples shown in Table 1. The oxidation resistance in Table 2 was determined by measuring the weight increase per unit time due to oxidation when kept at 900 ° C. in the atmosphere. The lubricity was evaluated by measuring the coefficient of friction with carbon steel. Vickers hardness was calculated from the indenter penetration depth under a load of 1 g using a nano indenter.

[0022]

[Table 2]

From Table 2, it is clear that Examples 1-27 of the present invention are superior to Comparative Examples 28-43 in all cases.

Table 3 shows the results of end mill cutting under the following specifications based on the examples shown in Table 1. Base material composition: 90WC-9.5Co-0.5Cr WC grain size: 0.8 μm Tool: 6 blades, end mill with a blade diameter of 8 mm Work material: SKD11 (HRC63) Cutting speed: 100 m / min Cutting depth: 8 mm x 0 2.8 mm feed: 50 μm / blade dry type life criterion was when the end mill was broken.

[0025]

[Table 3]

From Table 3, the invention examples 1 to 1 are shown in each case.
No. 27 has a long life and can cut 50 to 91 m, TiAl
The effect of the multilayer structure in which Cr and oxygen are added to the N system is clear.

Table 3 also shows the results when the examples shown in Table 1 were drilled with the following specifications. The thrust force is the result measured at the 10th hole in the initial stage of cutting. The life was evaluated by the number of holes when the drill was broken. Base material composition: 91, 5WC-8Co-0.5Cr WC grain size: 0.8 μm Work material: SKD61 (HRC42) Drill diameter 8 mm Cutting speed: 80 m / min Feed: 0.2 mm / rev Hole depth: 32 mm Dry type

From Table 3, it is apparent that Examples 1 to 27 of the present invention have extremely low thrust force and, as a result, long life.

Next, Examples 1 and 2 of the present invention were prepared using a cemented carbide insert.
7 and Comparative Examples 28 to 43 were prototyped, and cutting was performed with the following cutting specifications. The results are also shown in Table 3. These cutting specifications are conditions under which the cutting speed is high in face milling and the oxidation resistance of the tool is important. Base material: P30 grade cemented carbide insert: SEE42TN (20 ° clearance) Work material: SKD61 (HRC22) Cutting speed: 400 m / min Depth of cut: 1 mm Feed: 0.1 mm / Average flank wear is 0 for blade dry type life judgment The cutting time was taken to reach 0.4 mm.

From Table 3, it was confirmed that the examples of the present invention significantly improved the life.

[0031]

EFFECT OF THE INVENTION A TiAlCrON-based multilayer film obtained by adding Cr and oxygen to a TiAlN-based film not only improves oxidation resistance, but also imparts lubricity without deterioration of wear resistance, and a film by reducing stress. Adhesion can be improved and excellent characteristics can be exhibited in high speed dry cutting. Furthermore, by adjusting the film formation speed,
Achieves epitaxial growth of WC particles contained in the base material and the coating, and realizes a coated hard member with extremely excellent adhesion, and achieves stable cutting without peeling of the coating even in heavy cutting. is there. Further, the same effect is obtained in the application of hot forging.

Claims (11)

[Claims] 1. A hard coating member coated with a hard coating, wherein the hard coating is a coating containing Al, Ti, Cr, N and O, and the composition of each element is AlaTibCrcN.
When wO1-w, 30 ≦ a ≦ 70, 30 ≦ b ≦ 7
0, 0.5 ≦ c ≦ 20, a + b + c = 100, 0.7 ≦
w ≦ 0.99, and the half value width of the (200) plane diffraction peak in X-ray diffraction is 0.4 ° or more and 0.7 ° or less at 2θ, the hard coating member. 2. The hard film-coated member according to claim 1, wherein the number of layers of the hard film is one. 3. The hard film-coated member according to claim 1, wherein the hard film-coated member is a multilayer having two or more layers and 1,000 or less layers. 4. The hard coating member according to claim 1, wherein the film thickness of each layer is 5 nm or more and 2000 nm or less. 5. The hard coating member according to any one of claims 1 to 4, wherein the hard coating has a NaCl type crystal structure. 6. The hard coating member according to claim 1, wherein the diffraction intensity of the diffraction peak from the (111) plane is I (111) and the diffraction intensity of the diffraction peak from the (200) plane is I (200). ), I (200) / I (11
A hard film-coated member having a value of 1) of 1 or more and 20 or less. 7. The hard coating member according to any one of claims 1 to 6, wherein the crystal grains of the hard coating are columnar crystals or block-shaped crystals in which the columnar crystals are divided. 8. The hard film coating member according to claim 1, wherein the film crystal morphology of the hard film decreases from the base material surface side to the film surface, and the crystal grain size decreases. Element. 9. The hard coating member according to claim 1, wherein the coating crystal form is an amorphous form on the outermost surface side of the coating. 10. The hard coating member according to claim 1, wherein the residual compressive stress of the coating is 0.5 Gpa or more and 3.5 Gpa or less. 11. The hard film-coated member according to claim 1, wherein the film forming rate on the surface of the base material is relatively low,
A hard-coating member coated with a film having a relatively high film-forming rate on the surface side.