JP3205943B2 - Ti-rare earth element-N-based ultra-hard compound film and method of forming the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Ti-rare earth element-N
Regarding the system-based super-hard compound film and the method for forming the same, more specifically, tools used in the metal industry, the machine and equipment industries,
Ti-rare earth element-N-based ultra-hard compound film with improved hardness, abrasion resistance and sliding characteristics of the material surface by forming a coating film on the component parts used for various devices and the sliding material surface And a method for forming the film using an ion mixing method.

[0002]

2. Description of the Related Art Conventionally, as a hard / wear-resistant and slidable coating film formed on a substrate of this kind of metal or the like, Ti-N, PVD or CVD formed on the substrate has been used. Thin films of compounds such as Ti-C are known.

[0003] Thin films of these compounds such as Ti-N and Ti-C are formed by almost the same method. Among the above-mentioned methods, a typical example of the PVD coating is hollow cathode discharge, which has been widely used. The case of forming a Ti—N film on a substrate by the (HCD) -ion plating method will be described as follows.

[0004] First, an apparatus used in the PVD method will be described. FIG. 8 shows an HCD ion plating apparatus, in which a denotes a vacuum film forming chamber, and the inside of the vacuum film forming chamber a is connected to a vacuum pump b. Further, c is a substrate mainly made of a metal material to be provided for coating, d is a metal evaporation source hearth, and e is a metal material to be evaporated (here, T
i) and f are hollow cathode electron guns, g is a discharge power supply for applying a voltage to the hollow cathode electron gun f and the metal evaporation source hearth d, h is an electron beam, i is a nozzle for flowing N ₂ gas, j
Denotes a partially ionized N ₂ gas, and k denotes a bias power supply for applying a voltage to the substrate c.

Next, a method for forming a coating m of a Ti—N compound on a substrate c using the apparatus shown in FIG. 8 will be described.

First, after evacuating the inside of the vacuum film forming chamber a by the vacuum pump b, the Ar gas for discharge is supplied to the hollow cathode electron gun f, and a few tens of minutes are inserted between the hollow cathode electron gun f and the hearth d. A DC voltage of several hundred volts is applied from a discharge power source g to discharge between f and d.

At this time, a large amount of electron beams h generated by hollow cathode discharge in the hollow cathode electron gun f
Is irradiated to the metal material e (Ti) in the metal evaporation source hearth d, and the Ti of the metal material e is melted by heating by electron impact to generate a Ti neutral beam (Ti vapor). A part of the Ti neutral beam (Ti vapor) is ionized by bombardment with the electron beam h and Ar ions formed by hollow cathode discharge. At this time, since a negative DC bias voltage of several tens of volts is applied to the substrate c by the bias power source k, the ionized Ti ion beam is accelerated, and a Ti neutral beam (Ti
Together with the vapor) and enters the substrate c, and Ti
Form a film.

When forming a Ti—N film m on a substrate c, an N ₂ gas is supplied from a nozzle i through a Ti ion beam and a T
i The N ₂ gas flows at the same time as the irradiation of the neutral beam.
As in the case of the i-vapor, a part thereof is ionized and is incident on the surface of the substrate c together with the N ₂ neutral beam, where it reacts with the simultaneously incident Ti ion beam and Ti neutral beam to form the Ti—N film m. Will be formed.

[0009]

SUMMARY OF THE INVENTION PVD method or CV
The hardness of the film m on the substrate c formed by the method D is as follows.
About 22 Vickers hardness (Hv) for Ti-N film
00, about 3700 for the Ti-C film. Considering the adhesion between the formed Ti—N film and the substrate and between the Ti—C film and the substrate, the formed Ti—N film and the Ti—C
The film simply deposits on the surface of the substrate or is slightly mixed with the substrate surface layer by ion bombardment or thermal diffusion by bias. Therefore, Ti-N
The adhesion between the film or the Ti-C film and the substrate is not very good.

[0010] The conventional apparatus shown in FIG.
In the sample coated with the -N film m, the Ti-N film m is deposited on the substrate c with a clear interface as shown in the schematic diagram of FIG. Then, when a friction / sliding partner material is pressed against the sample shown in FIG. 9A, the Ti-N film m on the substrate c is hard and the adhesion of the Ti-N film m is small. As shown in FIG. 9 (B), a part of the Ti—N film m is separated from the surface of the substrate c and does not function as a wear-resistant and slidable film. In FIG. 9 (B), n represents a friction / sliding partner material, which corresponds to a partner material, a scratch of a film in actual use, or a partner material (indenter) in a friction / wear test.

As described above, when coating a wear-resistant film and a slidable film on a tool material or a sliding part of a precision instrument or the like, the meaning of hardening the coating film layer and suppressing peeling of the film is considered. Therefore, it is necessary to improve the life and performance of tools and components by improving the adhesion of the coating film to the substrate.

An object of the present invention is to provide a Ti-rare earth element-N-based super-hard compound having hardness and sliding characteristics higher than those of a conventionally used coating material such as a Ti-N film and a Ti-C film, and a method of forming the same on a substrate. Ti-rare earth element-N with excellent adhesion
An object of the present invention is to provide a method for forming a super hard compound film.

[0013]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the chemical bonding theory (revised version)
[Pauling, Translated by Masao Koizumi, Kyoritsu Shuppan Co., Ltd. 196
Attention was paid to the atomic radii (single bond radii) described in “May 20, 20th Revised 1st Issue”.

More specifically, a rare earth element has a larger atomic radius than a transition metal such as Ti, and its value is T
i: 1.32 °, for example, Dy: 1.60 °, Y:
1.62 °.

When a rare earth element is substituted for a Ti site in a Ti—N crystal matrix, Ti—X—N (X is a solid solution element, in this case, a rare earth element) due to lattice distortion due to the presence of an atom having a large radius. An increase in hardness can be expected.

On the other hand, whether or not an additive element forms a substitutional solid solution generally follows the Hume-Rothery's Rule, which is empirically given.

[0017] A Darken-Gurry's plot [Darken-Gurry's plot] of a Ti-M system (M represents a rare earth element or a transition metal element) with the electronegativity on the vertical axis and the atomic radius on the horizontal axis
(Ln represents a lanthanoid element in the figure). More specifically, according to FIG. 1, the center is Ti (the atomic radius of Ti is 1.32 °, and the electronegativity is 1.4). The circle is the solid solution range (Ti
Within ± 15% in atomic radius and ± 0.
Within 4%), the rare earth elements listed as the elements to be included in Ti-N in the present invention fall within the range of the electronegativity, but exceed the range in the + direction in the atomic radius (about + 20%). It has become. Therefore, it has been found that a Ti—X—N non-equilibrium compound containing such a rare earth element (X represents a rare earth element) can form a coating film with high hardness.

The Ti-rare earth element-N-based ultra-hard compound film and the method of forming the same according to the present invention have been made based on the above findings. In the formed thin film made of a Ti-N-based superhard compound, the hard compound thin film contains 0.5 to 20 atomic% of a rare earth element in a composition of Ti and N.
It is a thin film of the compound contained.

The reason why the content of the rare earth element contained in the composition comprising Ti and N is set to 0.5 to 20 atomic% is that when the content is less than 0.5 atomic%, hardening due to solid solution occurs. This is because the hardness is insufficient, and when the content exceeds 20 atomic%, the hardness of the obtained compound film becomes saturated.

A method for forming a Ti-rare earth element-N type ultra-hard compound film is to irradiate a substrate with a vapor metal from a metal evaporation source and a high-speed ion beam from an ion beam source to form an ultra-hard compound film on the substrate. Of one or more of Ti, N and rare earth elements constituting an ultra-hard compound as an ion beam, and the remaining element as a metal vapor or a beam of a gas containing these elements. Is applied to the substrate to form a super-hard compound film.

[0021]

The rare-earth element has a larger atomic radius than Ti, so that the addition of the rare-earth element in the composition of Ti and N causes a distortion in the crystal lattice of the compound synthesized, increasing the hardness. I do.

By irradiating the substrate with a high-speed ion beam from the ion beam, alloy elements on the substrate surface are quenched from the non-equilibrium state excited with high energy, and a non-equilibrium compound is synthesized.

Also, one of Ti, N, and rare earth elements,
Alternatively, by irradiating a plurality of elements onto the substrate in the form of an ion beam, Ti, N, the rare earth element, and the constituent elements of the substrate are combined by the ion irradiation impact at the interface between the Ti-rare earth element-N compound film and the substrate. Interfacial mixing, in which the elements of the substrate and the compound film are continuously mixed with each other due to the mixing effects of cutting, atom knock-on injection, thermal effects, etc. Form a layer. Due to the presence of the interface mixing layer, the adhesion between the substrate and the compound film is improved.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows an example of a film forming apparatus for forming a Ti-rare earth element-N-based ultra-hard compound film of the present invention. In the drawing, reference numeral 1 denotes a vacuum film forming chamber; The vacuum film forming chamber 1 is connected to a vacuum pump 2 via a pressure adjusting valve 3. Reference numeral 4 denotes a metal or ceramic substrate to be coated, 5 a substrate holder for holding the substrate 4, 6 a metal evaporation source hearth, 7 a Ti metal vapor (neutral beam), 8 an ion source and an ion accelerator. , 9 is an ion beam, 10 is a gas flow controller, 11 is a gas introduction nozzle, 12 is a gas beam, 13 is Ti metal to be evaporated, 1
Reference numeral 4 denotes a substrate heating heater.

Next, a specific example of forming a Ti-rare earth element-N-based ultra-hard compound film on a substrate using the above-described apparatus will be described together with a comparative example.

Embodiment 1 In this embodiment, the substrate 4 is made of steel (J) having a diameter of 40 mm and a thickness of 5 mm.
IS-SUS-440C, H RC> 60), and the rare earth element contained in Ti and N is dysprosium (Dy)
And

[0028] First, a pressure of 10 air vacuum deposition chamber 1 is discharged by a vacuum pump 2 ^- was set to a high vacuum degree of ⁵ Pa. Then, NH ₃ gas whose flow rate has been adjusted to 2.0 SCCM by the gas flow controller 10 is introduced as a gas beam 12 from the gas introduction nozzle 11 into the vacuum film forming chamber 1, and the opening of the pressure control valve 3 is adjusted to form a vacuum. The pressure in the membrane chamber 1 is 4 × 10 ^−
It was maintained at ⁴ Pa.

The substrate holder 5 is heated by the substrate heating heater 14.
The substrate 4 made of steel held at a temperature of 300 ° C. was heated and maintained at 300 ° C. In this state, the Ti metal 13 in the metal evaporation source hearth 6 was melted and evaporated by electron beam heating, and was irradiated onto the substrate 4 as Ti metal vapor (neutral beam) 7.

At the same time, the substrate 4 was irradiated with an ion beam 9 of dysprosium (Dy) extracted from the ion source and the ion accelerator 8. The deposition rate of the Ti metal 13 on the surface of the substrate 4 was 2.0 ° / sec. The energy of the dysprosium (Dy) ion beam is 30.
KeV and the current density were 5.6 μA / cm ² .

The operation under the above conditions is performed by using T
The process was continued until the thin film 15 of the i-Dy-N-based super-hard compound became 1 μm (see FIG. 7A).

When the crystal structure of the formed Ti-Dy-N-based ultra-hard compound film was examined by X-ray diffraction, the same crystal system (NaCl) as Ti-N having a lattice constant close to that of Ti-N was obtained.
Type).

The results of the lattice constant of the Ti—Dy—N ultrahard compound film obtained from the X-ray diffraction angle of the NaCl type crystal (200) plane are shown as plot symbol A in FIG. The atomic ratio on the horizontal axis in FIG.
Dy / Ti + Dy determined in A.

The Ti-Dy-N compound is (Ti 1-
x, Dy x) N y "where x = Dy / (Ti + Dy) atomic ratio, y = 0.67 to 1.13"
The characteristic value line G in FIG. 3 shows the value of the lattice constant (according to Beggers law) assuming that y was ideally substituted for the Ti site in the crystal.

The Vickers hardness (Hv) of the formed Ti-Dy-N-based ultra-hard compound film was measured by a Vickers hardness tester, and the result is shown by plot symbol A in FIG. The atomic ratio on the horizontal axis in FIG.
Dy / Ti + Dy determined by PMA.

A friction / wear test was performed on the formed Ti-Dy-N-based ultra-hard compound film in a vacuum, and the measurement result is shown as a curve H in FIG. The friction / wear test is performed by rotating the test sample and pressing a mating ball against a circumferential portion at a fixed distance from the center of rotation, which is generally called a pin-on-disk method. The friction and wear characteristics are evaluated based on the change in the coefficient of friction between the materials and the degree of wear of the circumferential friction track. The test conditions were SUS440C steel of φ7mm (HRC> 60), the distance from the center of rotation was 7.25mm, and the linear velocity of motion was 9.1m.
/ Min, and a pressing load of 514 g.

FIG. 6 (A) shows the cross-sectional shape of the friction track at 64 minutes after the start of the friction / wear test in vacuum of the Ti-Dy-N-based ultra-hard compound film. Further, the vertical axis change state of the curve I is enlarged, and this is shown as a curve J in FIG.

Examples 2 to 5 The NH ₃ gas flow rate was 2.0 to 6.0 SCCM, the Dy ion current density was 13.0 to 23.0 μA / cm ² , and the Ti deposition rate was 1.3 to 3.0 ° / cm. A Ti-Dy-N-based ultra-hard compound film 15 was formed on the substrate 4 in the same manner as in Example 1 except that the incident ratio of Ti, Dy, and N was changed in the condition range of seconds.
This was made into Examples 2, 3, 4, and 5.

From the X-ray diffraction angle of the NaCl-type crystal (200) plane of the Ti-Dy-N-based ultra-hard compound film of each of the formed examples, the lattice constant of the crystal was determined in the same manner as in Example 1.
The results are shown in FIG.
Is shown as plot symbol C, Example 4 is shown as plot symbol D, and Example 5 is shown as plot symbol E.

Further, the Ti-Dy-
The Vickers hardness (Hv) of the N-based ultra-hard compound film was measured by the same method as in Example 1, and the result was shown in FIG.
Is shown as plot symbol B, Example 4 is shown as plot symbol D, and Example 5 is shown as plot symbol E.

The NH ₃ gas flow rate (SCCM), Dy ion current density (μA / cm ² ), T
Table 1 shows the conditions of the i deposition rate (Å / sec).

[0042]

[Table 1]

Comparative Example 1 Using a conventional HCD ion plating apparatus shown in FIG. 8, a substrate (steel material having a diameter of 40 mm and a thickness of 5 mm [JIS-SUS
-440C, HRC> 60]) 1 μm thick Ti on c
-N film m is formed, and NaCl of the formed Ti-N film m is formed.
The lattice constant of the crystal was determined from the X-ray diffraction angle of the type crystal (200) plane in the same manner as in Example 1, and the result is shown as plot symbol F in FIG.

The Vickers hardness (Hv) of the formed Ti—N film was measured by the same method as in Example 1, and the result is shown as plot symbol F in FIG.

Further, a friction / wear test in vacuum of the formed Ti—N film was performed in the same manner as in Example 1. The measurement result is shown as a curve S in FIG. Further, the cross-sectional shape of the friction track at the end of the friction / wear test (the test end time is 64 minutes) is shown as a curve T in FIG. 6C.

As is apparent from FIG. 3, it was found that the measured value of the lattice constant of the embodiment of the present invention almost coincides with the predicted value of the lattice constant according to the Beggers law (characteristic value line G in FIG. 3). . On the other hand, the lattice constant value of Comparative Example 1 according to the conventional method was 4.24 °.

Further, as is apparent from FIG. 4, in the embodiment of the present invention, the Vickers hardness (Hv) increases as the content of Dy in the Ti-Dy-N-based super-hard compound increases, and the maximum hardness is 4000. On the other hand, in Comparative Example 1, the hardness was as low as 1800. Therefore, it was found that the hardness of a film obtained by adding a rare earth element to a composition comprising Ti-N can be increased.

As is clear from FIGS. 5 and 6, in the embodiment of the present invention, the friction coefficient shows a low value of about 0.04 up to the friction / wear test time of 182 minutes, and the wear of the sample surface is almost zero. It was not observed, and the roughness of the sample surface was about 500 to 1000 ° as shown in FIG.
The film thickness of the -N-based super-hard compound film is smaller than 1 μm (10000 °), and the substrate is hardly worn, whereas the coefficient of friction in Comparative Example 1 is as large as 0.6 from the initial stage of the friction / wear test. At 47 minutes after the start, a large change was observed in the friction coefficient, and the test had to be stopped at the test time of 64 minutes. Furthermore, as apparent from FIG. No Ti-N compound film was present, and it was observed that the substrate was deeply worn.
Therefore, in the examples of the present invention, it was found that a film obtained by incorporating a rare earth element into a composition composed of Ti-N has excellent wear resistance.

As described above, the T generated in the embodiment of the present invention is used.
The i-Dy-N-based super-hard compound film has a high hardness of the film itself and a peeling resistance due to a high adhesion to the substrate, so that a smooth friction and sliding surface can be obtained, and excellent friction and abrasion resistance is obtained. It was found to have.

This is shown in FIG. 7 [FIG. 7 (A) is a schematic view of the substrate 4 and the Ti-Dy-N compound film 15 of the Ti-Dy-N coating sample prepared in Example 1, and FIG. Is T
A schematic diagram showing a state in which the friction / wear partner 17 is pressed against the i-Dy-N compound film 15].

As is clear from FIG. 7A, the substrate 4 and T
The interface between the substrate 4 and the Ti-Dy-N-based ultra-hard compound film 15 is caused by the mixing effect of ion irradiation.
It can be seen that the elements of the N-based super-hard compound film 15 are continuously mixed with each other, and that the interface mixing layer 16 that firmly connects the substrate 4 and the Ti-Dy-N-based super-hard compound film 15 is formed.

As is clear from FIG. 7B, FIG.
Unlike the conventional Ti-N compound film of (B), the Ti-Dy-N-based ultra-hard compound film 15 formed on the substrate 4 is hard and has high adhesion of the film to the substrate.
Even when the friction / wear partner 17 is strongly pressed against the -N-based super-hard compound film 15, the Ti-Dy-N-based super-hard compound film 1
5 shows that the Ti-Dy-N-based ultra-hard compound film is not peeled off from the substrate 4 and the flatness of the film is maintained, so that it is excellent in wear resistance and slidability.

In the above embodiment, Dy was used as a rare earth element to be contained. However, the present invention is not limited to this, and yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), etc. May be included.

In the above embodiment, Dy + was used as the ion beam for irradiating the substrate, Ti gas was used as the neutral beam, and NH ₃ beam was used as the gas (molecular) beam. However, the present invention is not limited to this. Instead, as ion beams, Ti +, N +, N ₂ +, rare earth element ions,
Rare earth elements such as Dy, N atoms or N radical beams as neutral beams, and TiCl
₄ , TiBr ₄ , TiI ₄ , and N ₂ gas.
When irradiating the substrate, each may be used alone or with a plurality of mixed beams, and, if necessary, the composite beam combined with any one of the ion beam, the neutral beam, or the gas beam. Good.

[0055]

As described above, the Ti-rare earth element of the present invention
In the case of using an N-based super-hard compound film, the crystal lattice is distorted by a rare-earth element having a large atomic radius contained in the composition composed of Ti and N, and becomes a Ti-rare earth element-N non-equilibrium compound. Compared with the Ti-N-based compound film, the hardness is increased and the substrate has excellent adhesion to the substrate. Therefore, the substrate on which the super-hard compound film is formed has excellent friction sliding and abrasion resistance. And so on.

When the method of forming a Ti-rare earth element-N super hard compound film of the present invention is used, a part of Ti, N and the rare earth element constituting the super hard compound are deposited on the substrate in the form of an ion beam. Since irradiation and supply are performed, the compound element formed on the substrate is quenched from the non-equilibrium state excited by high energy, and the non-equilibrium compound Ti-rare earth element -N can be synthesized on the substrate. Due to the ion beam, intense mixing occurs between the film constituent element and the substrate constituent element at the interface between the Ti-rare earth element-N compound film and the substrate. This mixing causes the film constituent element at the interface part between the compound film and the substrate. And the constituent elements of the substrate are continuously mixed with each other to form an interfacial mixing layer that firmly connects the two with each other. There is an effect that can provide a method of very easily forming a good ultrahard compound film on the substrate.

[Brief description of the drawings]

FIG. 1 is a Daken-Garry plot of a Ti-M (M represents a rare earth element and a transition metal element) system,

FIG. 2 is a schematic explanatory view of one example of an apparatus for forming a Ti-rare earth element-N-based ultra-hard compound film of the present invention;

FIG. 3 is a characteristic value diagram showing a relationship between an atomic ratio (Dy / Ti + Dy) and a lattice constant of films formed in Examples of the present invention and Comparative Examples.

FIG. 4 is a characteristic value diagram showing a relationship between an atomic ratio (Dy / Ti + Dy) and Vickers hardness of films formed in Examples of the present invention and Comparative Examples.

FIG. 5 is a characteristic diagram showing a relationship between a test time and a coefficient of friction of a pin-on-disk friction test of the film samples formed in Examples of the present invention and Comparative Examples,

FIG. 6 is a cross-sectional view of a friction / wear track of a friction test sample after a lapse of the same time in a pin-on-disk friction test of the film samples formed in Examples of the present invention and Comparative Examples;
(A) and (B) are examples of the present invention, (C) is a comparative example,

FIGS. 7A and 7B are schematic diagrams of a film and a substrate formed in an example of the present invention, wherein FIG. 7A is a schematic diagram after film formation, and FIG. Pattern diagram

FIG. 8 is a schematic explanatory view of an apparatus for forming a conventional Ti—N-based compound film,

9A and 9B are schematic diagrams of a film and a substrate formed by a conventional method apparatus, wherein FIG. 9A is a schematic diagram after the film is formed, and FIG. 9B is a schematic diagram of a mating material pressed against the film in a friction / sliding state. FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 vacuum deposition chamber, 4 substrate, 6 metal evaporation source hearth, 7 Ti metal vapor (neutral beam), 8 ion source and ion accelerator, 9 ion beam, 10 gas introduction nozzle, 11
Gas beam, 12 gas beam, 1
3 Ti metal, 15 Ti-rare earth element-N based compound film.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 41/80-41/91 C23C 14/00-14/58

Claims (2)

(57) [Claims] 1. A thin film of a Ti—N-based ultra-hard compound formed on a substrate, wherein the thin film of the hard compound is T
0.5 to 2 rare earth elements in a composition comprising i and N
A Ti-rare earth element-N-based ultra-hard compound film, which is a thin film of a compound containing 0 atomic%. 2. An ion mixing method for irradiating a substrate with a vapor metal from a metal evaporation source and a high-speed ion beam from an ion beam source to form an ultra-hard compound film on the substrate. One or more of the constituent Ti, N and rare earth elements are used as an ion beam, and the remaining elements are combined with a metal vapor or a beam of a gas containing these elements to form an ultra-hard compound film. Forming a Ti-rare earth element-N-based ultra-hard compound film.