JP2914142B2 - Gradient composition film, method for producing the same, and 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 film formed on a hard base material such as a cutting tool for improving abrasion resistance and surface protection function.

[0002]

2. Description of the Related Art Conventionally, in cutting tools and wear-resistant tools, in order to improve the wear resistance and surface protection function, the surface of a hard base material made of WC-based cemented carbide, cermet, ceramics, high-speed steel, etc. is used. Is TiD by PVD or CVD
It is well known to form a single layer or multiple layers of carbide, nitride or carbonitride of Al (titanium), Hf (hafnium) or Zr (zirconium) or Al oxide.

On the other hand, the physical and chemical properties of metals and ceramics are significantly different, and there is a current situation in which sufficient adhesion between them cannot be obtained. Therefore, in iron and steel, No. 77 (1991), No. 5, a metal-ceramic composite coating film, that is, a metal component and a ceramic component are suitably used as a coating film having a good compatibility with a metal material and having various functions. It is proposed that a multifunctional film having both characteristics can be formed by selecting and combining them. Furthermore, Nagasaki Prefecture Industrial Technology Center Research Report, No. 5 (1990), pp. 75-80, for the purpose of improving the adhesion strength of the coating to the substrate, by continuously changing the pressure of each atmosphere gas at the time of preparing the coating for TiN and TiC, Ti
/ TiN and Ti / TiN / TiC graded composition films have been fabricated and their properties have been studied.

[0004] However, in the above-mentioned conventional hard coating layers, although the coating layers themselves have high hardness and abrasion resistance, there is a problem in adhesion strength to a substrate. On the other hand, when a composition that emphasizes adhesion strength is used, there is a problem that hardness is reduced. Furthermore, when a coating layer having a thickness of 100 μm or more is applied to a substrate, there is a problem that peeling of the layer occurs due to internal stress of the film. When these coating layers are used for a tool or the like, there is also a problem that the film is peeled or chipped during use because the film has low toughness against the action of an impact force such as intermittent cutting. Thus, in the conventional material, various characteristics required for the coating,
Specifically, it is difficult to simultaneously add adhesion and toughness required on the surface of the base material, hardness and abrasion resistance required on the surface of the coating film.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating having improved wear resistance and hardness, and significantly improved toughness and adhesion to a substrate, because of a cutting tool or a wear-resistant tool. To provide.

[0006]

Means for Solving the Problems The gradient composition film of the present invention comprises:
This is a film that is separately formed on a substrate made of at least one of a metal and a ceramic , and covers the surface of the substrate to provide higher hardness or wear resistance than the substrate. The film of the present invention includes at least one metal element M1 selected from the group consisting of iron, cobalt, and nickel;
At least one metal element M2 selected from the group consisting of group IVa, Va and VIa metal elements of the periodic table;
At least one selected from the group consisting of carbon and nitrogen
And two elements X. Further, the film of the present invention has a metal element M
The main component is a composite material composed of a compound of 2 and element X and a metal element M1. In the film of the present invention, the metal element M
The content of 1 decreases or increases at a substantially constant rate from the portion in contact with the substrate to the surface.

Further, according to the present invention, it is possible to provide a tool provided with the above-mentioned membrane. The tool of the present invention includes a substrate made of at least one of a metal and a ceramic, and a film separately formed on the substrate and covering the surface of the substrate and giving higher hardness or wear resistance than the substrate. Prepare. This film has the characteristics of the film of the present invention described above. In this tool, the substrate can be formed, for example, from a WC based cemented carbide, cermet, ceramics, high speed steel, or a combination thereof.

In the present invention, the metal element M2 is Ti,
Hf, Zr, Cr, V, Nb, W, Mo, Ta and the like are included.

Referring to FIG. 1, in accordance with the present invention, a substrate 10
It is assumed that the gradient composition film 20 is formed thereon. It is preferable to use, for example, WC-based cemented carbide, cermet, ceramics, and high-speed steel for base material 10. The thickness D of the film 20 formed on the base material 10 is 100 to 1000 μm. As described above, the film 20 is made of the metal elements M1 and M2 and the element X, and can be made of, for example, a composite material of M1 and the compound M2X (hereinafter, referred to as M1-M2X). In this film, the content of M1 decreases or increases from the portion 20a where the film comes into contact with the substrate (the portion corresponding to the boundary with the substrate) 20a to the surface 20b of the film.

When the M1 content decreases in the thickness direction of the film, it can be reduced, for example, as shown in FIG. In this figure, the M1 content decreases at a constant rate. Note that any deviation from such a linear decrease is also within the scope of the present invention. When the substrate is made of a metal such as a cemented carbide, such a decrease in M1 is preferable.

When the M1 content increases in the thickness direction of the film, it can be increased, for example, as shown in FIG. In this figure, the M1 content increases at a constant rate. Any deviation from such a linear increase is also within the scope of the present invention. When the substrate is made of ceramics, M1 can be increased in this way.

[0012] For M1 content inclined as shown above, and M1 content of part film is in contact with the substrate, the difference between M1 content of the membrane surface, is not less than 20 atm%.

According to the present invention, there is provided a method for depositing a film which imparts higher hardness or wear resistance than a substrate on a surface of a substrate comprising at least one of a metal and a ceramic. In this method, at least one metal element selected from the group consisting of iron, cobalt and nickel is placed in a vacuum vessel into which a gas containing a source of at least one element X selected from the group consisting of carbon and nitrogen has been introduced. First evaporation source for M1 and IV of the periodic table
and a second evaporation source for at least one metal element M2 selected from the group consisting of a, Va and VIa group metal elements. While moving the substrate along a straight line substantially parallel to a straight line connecting the first evaporation source and the second evaporation source,
PVD using cathodic arc discharge is performed. This PV
Due to D, a composite material composed of a compound of M2 and X and M1 as a main component on the base material, and the content of M1 decreases or increases at a substantially constant rate from the initial stage to the final stage of film formation. A film is formed.

In this method, for example, two evaporation sources are installed vertically or horizontally, and the base material is vertically moved (vertically) on a plane parallel to a plane containing the two evaporation sources.
Alternatively, it can be moved left and right (horizontally). In this case, the rate of change of the gradient composition (for example, the rate of decrease or increase of M1 in the film thickness direction) can be adjusted by the moving speed of the substrate.

In the method of the present invention, PVD using cathodic arc discharge is employed because a ceramic film having a remarkably high melting point and hardness can be formed at a temperature of 500 ° C. or less, and the strength of the substrate can be easily increased. This is because it is preferable in the production method of the gradient composition film because it can be maintained at a lower temperature.

[0016]

According to the relationship between the standard constituent free energies of nitrides and carbides, Fe, Co and Ni are unlikely to form nitrides, carbides and carbonitrides, while the periodic tables IVa, Va and VIa
Group metal elements tend to form nitrides, carbides, and carbonitrides. For this reason, according to the present invention, a compound consisting of a combination of a metal element from Groups IVa, Va, and VIa of the periodic table with at least one of C and N, Fe, C
A composite material film made of o, Ni, or a combination thereof can be produced. The prepared film is thermally stable. It should be noted that the film according to the present invention is made of an unreacted metal element
May be slightly contained.

In the film of the present invention, the content of the metal element M1 changes at a constant rate from the surface of the substrate toward the film thickness direction. M1 content of the part in contact with the substrate and M of the film surface
1 the difference between the content is more than 20 atm%. When such a gradient composition of M1 is used, for example, a rich layer of Fe, Co, or Ni having higher toughness than ceramics is formed on the surface of the base material and a portion close thereto, and the adhesion and toughness of the coating film to the base material are obtained. Is improved. Then, as the surface of the coating is reached, a rich layer of a compound comprising a combination of M2 and C and / or N is formed, and the hardness of the coating is increased. By adopting such a configuration, multi-functionalization that has been difficult with a film having a uniform composition, that is, achieving both high toughness and high hardness is realized. Further, the internal stress in the film can be controlled by the gradient composition. By relaxing the stress at the interface between the film and the substrate, it is possible to suppress the peeling of the film.

The reason why the M1 content in the gradient composition film is changed at a substantially constant rate from the substrate surface in the film thickness direction is that the composition change in the film occurs rapidly during the film formation. , Abnormalities in the coating at that location (eg cracks)
This was because it was found through experiments that the film was peeled off after the film formation was completed. In the method of the present invention, the moving speed of the substrate is controlled so that the M1 content in the film changes at a substantially constant rate.

As for the M1 content, by making the difference between the portion of the film in contact with the substrate and the film surface at least 20 atm%, as shown in the following examples, a metal-ceramic composite film having a uniform composition is obtained. Compared with the above, characteristics such as toughness can be remarkably improved.

Furthermore, since the present invention is used in bulk as a material replacing conventional high-speed tool steel and cemented carbide, a film having a thickness of 100 μm to 1000 μm can be formed on the surface of a hard member. By setting the thickness to 100 μm or more, it is possible to eliminate the influence of the properties of the substrate and exhibit excellent performance on the film. The thickness is desirably up to 1000 μm in view of the time required for formation and cost.

In the synthesis of the material of the present invention, an ion plating method using cathodic arc discharge is used. The material evaporated by the cathodic arc discharge includes not only those emitted as atoms or ions, but also many emitted as nanometer-sized clusters. Therefore, a gradient composition film in which ultrafine particles are dispersed can be easily formed as compared with other PVD or CVD.

Due to the characteristics of the film as described above, for example, when the coating of the present invention is used for a cutting tool or a wear-resistant tool, the wear life of the tool can be extended.

[0023]

EXAMPLES The effects of the gradient composition film of the present invention will be specifically described below with reference to examples.

In the following examples, the M1 content in the graded composition films shown in Tables 1, 2 and 3 was measured by energy dispersive X-ray spectroscopy (EDX) analysis on the film cross section. In the coating, portions other than M1 are M2C, M
2N, or M2CN.

Example 1 As a substrate, a flat plate (20 m
mx 20 mm x 1 mmt) was prepared. Eleven types of graded composition films shown in Table 1 were formed on the surfaces by ion plating using a known cathodic arc discharge as described below.

In forming a film, as shown in FIG. 4, two evaporation sources 2 and 3 are vertically arranged in a film forming apparatus 1 and can be moved on a front plane parallel to a plane including the evaporation sources. The base member 5 was mounted on the holder 4. By adjusting one or both of the vertical movement speed of the base material (moving the base material left and right when the evaporation source is installed in the horizontal direction) and the cathode arc discharge current (controlling the amount of evaporation of the evaporation source material) The rate of change of the gradient composition was controlled to be constant. The degree of vacuum in the film forming apparatus 1 was set to 10 ⁻⁵ Torr, and then Ar (argon) was used.
The substrate was heated to 500 ° C. while maintaining the atmosphere at 10 ⁻² Torr by introducing a gas, and the substrate was cleaned by applying a voltage of −1000 V, and then the Ar gas was exhausted. next,
Either N ₂ gas or CH ₄ gas in the film forming apparatus 1
Either type or both were introduced while controlling the time so that a predetermined pressure was obtained in accordance with the movement of the substrate. By cathodic arc discharge, Fe, Co or Ni and Periodic Table IV
M1-M2C, M1-M on a moving substrate by evaporating and ionizing metal elements of a, Va, and VIa groups.
A film consisting of 2N or M1-M2CN was formed. When the substrate is close to the M1 evaporation source, the content of M1 increases,
The content of M1 decreased with increasing distance. On the other hand, as the substrate approaches the M2 evaporation source,
The content of C, M2N or M2CN was increasing.

For comparison, coating samples of conventional examples (samples 12 to 14) shown in Table 1 were also prepared. Sample 12
No. -14 is a film obtained by using an ordinary PVD film forming apparatus and forming a film having a uniform composition on the surface of the substrate by an ion plating method using cathodic arc discharge.

Table 1 shows the mechanical properties of the obtained film. As for hardness, Knoop hardness under a load of 25 gf was measured. The toughness of the film was evaluated by a crack from an indentation caused by a Vickers indenter under a load of 1 kgf. Table 1
As can be seen from the graph, the material according to the present invention has a hardness equivalent to that of the conventional homogeneous composition film, and it can be said that the toughness is clearly superior to the conventional one.

Further, in order to examine the toughness, indentations (100 gf, 500 gf, 1 kgf) were made on the surface of the sample, and the surface of the portion was observed with a microscope. Table 2 shows the measurement results. As can be seen from Table 2, in the uniform composition film, cracks were formed by indentation and the film was peeled off. On the other hand, in the gradient composition film, almost no cracks occurred,
No peeling of the film has occurred. From the above results, it can be seen that the use of the gradient composition film as the surface coating layer greatly improves the adhesion to the substrate and the toughness of the coating.

[0030]

[Table 1]

[0031]

[Table 2]

Example 2 In this example, samples 1 to 14 shown in Table 3 were prepared using the same base material as in the above example and in the same manner. here,
Samples 12-14 are films having a uniform composition prepared for comparison, and those excluding these are the gradient composition films of the present invention.

Table 3 shows the relationship between the thickness of the gradient composition film and the residual stress. The residual stress was determined based on the warpage of the substrate before and after the formation of the coating. As is clear from Table 3, in the conventional uniform composition film, peeling occurs due to the internal stress of the film.
It was difficult to form a thick film of 50 μm or more.
However, by forming a film having a gradient composition according to the present invention, the internal stress in the film can be controlled.
By alleviating the stress at the interface of the film, it was possible to suppress the peeling of the film.
It has become possible to form a coating having a thickness of μm to 1000 μm.

[0034]

[Table 3]

Example 3 The films of samples 2, 4, 8, 9, and 14 in Table 1 were coated with cemented carbide (8
A tool was manufactured by coating the surface of 0% WC-10% TiC-5% Co), and the tool was used to cut SCM435 at a cutting speed of 150 m / min, a feed of 0.6 mm / rev, and a cutting depth of 2.0 mm. As a result, those coated with the films of Samples 2, 4, 8, and 9 of the present invention could be cut for 30 minutes. On the other hand, the sample 14 of the conventional product provided with the film lost in one minute. Thus, by coating the surface of the hard member with the gradient composition film, the life of the cutting tool can be extended.

[0036]

The gradient composition film of the present invention maintains the strength of the base material of the cutting tool or the wear-resistant tool, and at the same time has more excellent adhesion and wear resistance than before. Thus, especially in high speed cutting applications, the membranes of the present invention can be expected to significantly extend tool life.

Further, the internal stress in the film can be controlled by the gradient composition. By alleviating the stress at the interface of the film, peeling can be suppressed, and a film having a thickness of 100 μm to 1000 μm, which has been conventionally difficult, can be formed.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating the composition of a film according to the present invention.

FIG. 2 is a diagram showing an example of a change in the M1 content of a film according to the present invention.

FIG. 3 shows another example of the change in the M1 content of the membrane according to the invention.

FIG. 4 is a schematic view showing an example of an apparatus for forming a gradient composition film according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2, 3 Evaporation source 4 Holder (with a vertical movement mechanism) 5 Base material

Continuation of the front page (72) Inventor Toshio Nomura 1-1-1 Kunyokita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (56) References JP-A-3-229856 (JP, A) JP-A-3-229856 JP-A-1-287245 (JP, A) JP-A-2-22453 (JP, A) JP-A-2-124949 (JP, A) JP-A-3-90574 (JP, A) JP-A-3-197664 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 14/00-14/58 B23B 27/14 B23P 15/28

Claims (3)

(57) [Claims] 1. A film which is separately formed on a base material made of at least one of a metal and ceramics and covers the surface of the base material to give higher hardness or wear resistance than the base material. At least one metal element M1 selected from the group consisting of iron, cobalt and nickel; at least one metal element M2 selected from the group consisting of group IVa, Va and VIa metal elements of the periodic table; At least one selected from the group consisting of nitrogen
One of consisting the element X, a compound of a metal element M2 and the element X, a composite material comprising a metal element M1 Metropolitan as a main component, and 100μm or more 10
The thickness of the metal element M1 is less than or equal to 00 μm, and the content of the metal element M1 decreases or increases at a substantially constant rate from the part contacting the base material to the surface , and the metal in the part contacting the base material element
Content of M1 and Content of Metal Element M1 on the Film Surface
A gradient composition film, wherein a difference from the amount is 20 atm% or more . 2. A method for depositing a film imparting higher hardness or abrasion resistance than the base material on a surface of a base material made of at least one of a metal and a ceramic, the method comprising carbon and nitrogen. At least one selected from the group
In a vacuum vessel into which a gas containing a source of two elements X has been introduced,
A first evaporation source for at least one metal element M1 selected from the group consisting of iron, cobalt and nickel and at least one metal selected from the group consisting of group IV, Va and VIa metal elements of the periodic table; A second evaporation source for the metal element M2 is disposed, and the cathode arc discharge is performed while moving the substrate along a straight line substantially parallel to a straight line connecting the first evaporation source and the second evaporation source. By performing PVD using, a composite material composed of a compound of a metal element M2 and an element X and a metal element M1 as a main component, and the content of the metal element M1 is reduced on the base material. A method for producing a gradient composition film, comprising forming a film that decreases or increases at a substantially constant rate from the initial stage to the final stage. 3. A base material made of at least one of a metal and a ceramic, and a film separately formed on the base material and covering the surface of the base material and giving higher hardness or wear resistance than the base material Wherein the film is selected from the group consisting of at least one metal element M1 selected from the group consisting of iron, cobalt and nickel, and the group consisting of metal elements IV, Va and VIa of the periodic table. At least one metal element M2, and at least one selected from the group consisting of carbon and nitrogen
One of consisting the element X, a compound of a metal element M2 and the element X, a composite material comprising a metal element M1 Metropolitan as a main component, and 100μm or more 10
Has a thickness of less than 00Myuemu, contact at the film, the content of the metal element M1 is, has decreased or increased a generally constant rate toward the surface from the portion in contact with said substrate, and said substrate Part to do
Content of metal element M1 in gold and gold on the film surface
A tool characterized in that the difference from the content of the element M1 is 20 atm% or more .